path: root/static/freebsd/man9/bus_space.9 3.html

<table class="head">
  <tr>
    <td class="head-ltitle">BUS_SPACE(9)</td>
    <td class="head-vol">Kernel Developer's Manual</td>
    <td class="head-rtitle">BUS_SPACE(9)</td>
  </tr>
</table>
<div class="manual-text">
<section class="Sh">
<h1 class="Sh" id="NAME"><a class="permalink" href="#NAME">NAME</a></h1>
<p class="Pp"><code class="Nm">bus_space</code>,
    <code class="Nm">bus_space_barrier</code>,
    <code class="Nm">bus_space_copy_region_1</code>,
    <code class="Nm">bus_space_copy_region_2</code>,
    <code class="Nm">bus_space_copy_region_4</code>,
    <code class="Nm">bus_space_copy_region_8</code>,
    <code class="Nm">bus_space_copy_region_stream_1</code>,
    <code class="Nm">bus_space_copy_region_stream_2</code>,
    <code class="Nm">bus_space_copy_region_stream_4</code>,
    <code class="Nm">bus_space_copy_region_stream_8</code>,
    <code class="Nm">bus_space_free</code>,
    <code class="Nm">bus_space_map</code>,
    <code class="Nm">bus_space_peek_1</code>,
    <code class="Nm">bus_space_peek_2</code>,
    <code class="Nm">bus_space_peek_4</code>,
    <code class="Nm">bus_space_peek_8</code>,
    <code class="Nm">bus_space_poke_1</code>,
    <code class="Nm">bus_space_poke_2</code>,
    <code class="Nm">bus_space_poke_4</code>,
    <code class="Nm">bus_space_poke_8</code>,
    <code class="Nm">bus_space_read_1</code>,
    <code class="Nm">bus_space_read_2</code>,
    <code class="Nm">bus_space_read_4</code>,
    <code class="Nm">bus_space_read_8</code>,
    <code class="Nm">bus_space_read_multi_1</code>,
    <code class="Nm">bus_space_read_multi_2</code>,
    <code class="Nm">bus_space_read_multi_4</code>,
    <code class="Nm">bus_space_read_multi_8</code>,
    <code class="Nm">bus_space_read_multi_stream_1</code>,
    <code class="Nm">bus_space_read_multi_stream_2</code>,
    <code class="Nm">bus_space_read_multi_stream_4</code>,
    <code class="Nm">bus_space_read_multi_stream_8</code>,
    <code class="Nm">bus_space_read_region_1</code>,
    <code class="Nm">bus_space_read_region_2</code>,
    <code class="Nm">bus_space_read_region_4</code>,
    <code class="Nm">bus_space_read_region_8</code>,
    <code class="Nm">bus_space_read_region_stream_1</code>,
    <code class="Nm">bus_space_read_region_stream_2</code>,
    <code class="Nm">bus_space_read_region_stream_4</code>,
    <code class="Nm">bus_space_read_region_stream_8</code>,
    <code class="Nm">bus_space_read_stream_1</code>,
    <code class="Nm">bus_space_read_stream_2</code>,
    <code class="Nm">bus_space_read_stream_4</code>,
    <code class="Nm">bus_space_read_stream_8</code>,
    <code class="Nm">bus_space_set_multi_1</code>,
    <code class="Nm">bus_space_set_multi_2</code>,
    <code class="Nm">bus_space_set_multi_4</code>,
    <code class="Nm">bus_space_set_multi_8</code>,
    <code class="Nm">bus_space_set_multi_stream_1</code>,
    <code class="Nm">bus_space_set_multi_stream_2</code>,
    <code class="Nm">bus_space_set_multi_stream_4</code>,
    <code class="Nm">bus_space_set_multi_stream_8</code>,
    <code class="Nm">bus_space_set_region_1</code>,
    <code class="Nm">bus_space_set_region_2</code>,
    <code class="Nm">bus_space_set_region_4</code>,
    <code class="Nm">bus_space_set_region_8</code>,
    <code class="Nm">bus_space_set_region_stream_1</code>,
    <code class="Nm">bus_space_set_region_stream_2</code>,
    <code class="Nm">bus_space_set_region_stream_4</code>,
    <code class="Nm">bus_space_set_region_stream_8</code>,
    <code class="Nm">bus_space_subregion</code>,
    <code class="Nm">bus_space_unmap</code>,
    <code class="Nm">bus_space_write_1</code>,
    <code class="Nm">bus_space_write_2</code>,
    <code class="Nm">bus_space_write_4</code>,
    <code class="Nm">bus_space_write_8</code>,
    <code class="Nm">bus_space_write_multi_1</code>,
    <code class="Nm">bus_space_write_multi_2</code>,
    <code class="Nm">bus_space_write_multi_4</code>,
    <code class="Nm">bus_space_write_multi_8</code>,
    <code class="Nm">bus_space_write_multi_stream_1</code>,
    <code class="Nm">bus_space_write_multi_stream_2</code>,
    <code class="Nm">bus_space_write_multi_stream_4</code>,
    <code class="Nm">bus_space_write_multi_stream_8</code>,
    <code class="Nm">bus_space_write_region_1</code>,
    <code class="Nm">bus_space_write_region_2</code>,
    <code class="Nm">bus_space_write_region_4</code>,
    <code class="Nm">bus_space_write_region_8</code>,
    <code class="Nm">bus_space_write_region_stream_1</code>,
    <code class="Nm">bus_space_write_region_stream_2</code>,
    <code class="Nm">bus_space_write_region_stream_4</code>,
    <code class="Nm">bus_space_write_region_stream_8</code>,
    <code class="Nm">bus_space_write_stream_1</code>,
    <code class="Nm">bus_space_write_stream_2</code>,
    <code class="Nm">bus_space_write_stream_4</code>,
    <code class="Nm">bus_space_write_stream_8</code> &#x2014;
    <span class="Nd">bus space manipulation functions</span></p>
</section>
<section class="Sh">
<h1 class="Sh" id="SYNOPSIS"><a class="permalink" href="#SYNOPSIS">SYNOPSIS</a></h1>
<p class="Pp"><code class="In">#include
    &lt;<a class="In">machine/bus.h</a>&gt;</code></p>
<p class="Pp"><var class="Ft">int</var>
  <br/>
  <code class="Fn">bus_space_map</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_addr_t address</var>,
    <var class="Fa">bus_size_t size</var>, <var class="Fa">int flags</var>,
    <var class="Fa">bus_space_handle_t *handlep</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_unmap</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t size</var>);</p>
<p class="Pp"><var class="Ft">int</var>
  <br/>
  <code class="Fn">bus_space_subregion</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">bus_size_t
    size</var>, <var class="Fa">bus_space_handle_t *nhandlep</var>);</p>
<p class="Pp"><var class="Ft">int</var>
  <br/>
  <code class="Fn">bus_space_alloc</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_addr_t reg_start</var>,
    <var class="Fa">bus_addr_t reg_end</var>, <var class="Fa">bus_size_t
    size</var>, <var class="Fa">bus_size_t alignment</var>,
    <var class="Fa">bus_size_t boundary</var>, <var class="Fa">int flags</var>,
    <var class="Fa">bus_addr_t *addrp</var>, <var class="Fa">bus_space_handle_t
    *handlep</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_free</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t size</var>);</p>
<p class="Pp"><var class="Ft">int</var>
  <br/>
  <code class="Fn">bus_space_peek_1</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint8_t
    *datap</var>);</p>
<p class="Pp"><var class="Ft">int</var>
  <br/>
  <code class="Fn">bus_space_peek_2</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint8_t
    *datap</var>);</p>
<p class="Pp"><var class="Ft">int</var>
  <br/>
  <code class="Fn">bus_space_peek_4</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint8_t
    *datap</var>);</p>
<p class="Pp"><var class="Ft">int</var>
  <br/>
  <code class="Fn">bus_space_peek_8</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint8_t
    *datap</var>);</p>
<p class="Pp"><var class="Ft">int</var>
  <br/>
  <code class="Fn">bus_space_poke_1</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint8_t
    *datap</var>);</p>
<p class="Pp"><var class="Ft">int</var>
  <br/>
  <code class="Fn">bus_space_poke_2</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint8_t
    *datap</var>);</p>
<p class="Pp"><var class="Ft">int</var>
  <br/>
  <code class="Fn">bus_space_poke_4</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint8_t
    *datap</var>);</p>
<p class="Pp"><var class="Ft">int</var>
  <br/>
  <code class="Fn">bus_space_poke_8</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint8_t
    *datap</var>);</p>
<p class="Pp"><var class="Ft">uint8_t</var>
  <br/>
  <code class="Fn">bus_space_read_1</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>);</p>
<p class="Pp"><var class="Ft">uint16_t</var>
  <br/>
  <code class="Fn">bus_space_read_2</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>);</p>
<p class="Pp"><var class="Ft">uint32_t</var>
  <br/>
  <code class="Fn">bus_space_read_4</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>);</p>
<p class="Pp"><var class="Ft">uint64_t</var>
  <br/>
  <code class="Fn">bus_space_read_8</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>);</p>
<p class="Pp"><var class="Ft">uint8_t</var>
  <br/>
  <code class="Fn">bus_space_read_stream_1</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>);</p>
<p class="Pp"><var class="Ft">uint16_t</var>
  <br/>
  <code class="Fn">bus_space_read_stream_2</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>);</p>
<p class="Pp"><var class="Ft">uint32_t</var>
  <br/>
  <code class="Fn">bus_space_read_stream_4</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>);</p>
<p class="Pp"><var class="Ft">uint64_t</var>
  <br/>
  <code class="Fn">bus_space_read_stream_8</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_write_1</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint8_t
    value</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_write_2</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint16_t
    value</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_write_4</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint32_t
    value</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_write_8</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint64_t
    value</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_write_stream_1</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint8_t
    value</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_write_stream_2</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint16_t
    value</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_write_stream_4</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint32_t
    value</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_write_stream_8</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint64_t
    value</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_barrier</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">bus_size_t
    length</var>, <var class="Fa">int flags</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_read_region_1</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint8_t
    *datap</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_read_region_2</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint16_t
    *datap</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_read_region_4</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint32_t
    *datap</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_read_region_8</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint64_t
    *datap</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_read_region_stream_1</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint8_t
    *datap</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_read_region_stream_2</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint16_t
    *datap</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_read_region_stream_4</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint32_t
    *datap</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_read_region_stream_8</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint64_t
    *datap</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_write_region_1</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint8_t
    *datap</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_write_region_2</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint16_t
    *datap</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_write_region_4</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint32_t
    *datap</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_write_region_8</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint64_t
    *datap</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_write_region_stream_1</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint8_t
    *datap</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_write_region_stream_2</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint16_t
    *datap</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_write_region_stream_4</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint32_t
    *datap</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_write_region_stream_8</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint64_t
    *datap</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_copy_region_1</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t srchandle</var>,
    <var class="Fa">bus_size_t srcoffset</var>,
    <var class="Fa">bus_space_handle_t dsthandle</var>,
    <var class="Fa">bus_size_t dstoffset</var>, <var class="Fa">bus_size_t
    count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_copy_region_2</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t srchandle</var>,
    <var class="Fa">bus_size_t srcoffset</var>,
    <var class="Fa">bus_space_handle_t dsthandle</var>,
    <var class="Fa">bus_size_t dstoffset</var>, <var class="Fa">bus_size_t
    count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_copy_region_4</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t srchandle</var>,
    <var class="Fa">bus_size_t srcoffset</var>,
    <var class="Fa">bus_space_handle_t dsthandle</var>,
    <var class="Fa">bus_size_t dstoffset</var>, <var class="Fa">bus_size_t
    count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_copy_region_8</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t srchandle</var>,
    <var class="Fa">bus_size_t srcoffset</var>,
    <var class="Fa">bus_space_handle_t dsthandle</var>,
    <var class="Fa">bus_size_t dstoffset</var>, <var class="Fa">bus_size_t
    count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_copy_region_stream_1</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t srchandle</var>,
    <var class="Fa">bus_size_t srcoffset</var>,
    <var class="Fa">bus_space_handle_t dsthandle</var>,
    <var class="Fa">bus_size_t dstoffset</var>, <var class="Fa">bus_size_t
    count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_copy_region_stream_2</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t srchandle</var>,
    <var class="Fa">bus_size_t srcoffset</var>,
    <var class="Fa">bus_space_handle_t dsthandle</var>,
    <var class="Fa">bus_size_t dstoffset</var>, <var class="Fa">bus_size_t
    count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_copy_region_stream_4</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t srchandle</var>,
    <var class="Fa">bus_size_t srcoffset</var>,
    <var class="Fa">bus_space_handle_t dsthandle</var>,
    <var class="Fa">bus_size_t dstoffset</var>, <var class="Fa">bus_size_t
    count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_copy_region_stream_8</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t srchandle</var>,
    <var class="Fa">bus_size_t srcoffset</var>,
    <var class="Fa">bus_space_handle_t dsthandle</var>,
    <var class="Fa">bus_size_t dstoffset</var>, <var class="Fa">bus_size_t
    count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_set_region_1</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint8_t
    value</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_set_region_2</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint16_t
    value</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_set_region_4</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint32_t
    value</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_set_region_8</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint64_t
    value</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_set_region_stream_1</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint8_t
    value</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_set_region_stream_2</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint16_t
    value</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_set_region_stream_4</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint32_t
    value</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_set_region_stream_8</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint64_t
    value</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_read_multi_1</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint8_t
    *datap</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_read_multi_2</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint16_t
    *datap</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_read_multi_4</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint32_t
    *datap</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_read_multi_8</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint64_t
    *datap</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_read_multi_stream_1</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint8_t
    *datap</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_read_multi_stream_2</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint16_t
    *datap</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_read_multi_stream_4</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint32_t
    *datap</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_read_multi_stream_8</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint64_t
    *datap</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_write_multi_1</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint8_t
    *datap</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_write_multi_2</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint16_t
    *datap</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_write_multi_4</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint32_t
    *datap</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_write_multi_8</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint64_t
    *datap</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_write_multi_stream_1</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint8_t
    *datap</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_write_multi_stream_2</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint16_t
    *datap</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_write_multi_stream_4</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint32_t
    *datap</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_write_multi_stream_8</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint64_t
    *datap</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_set_multi_1</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint8_t
    value</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_set_multi_2</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint16_t
    value</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_set_multi_4</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint32_t
    value</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_set_multi_8</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint64_t
    value</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_set_multi_stream_1</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint8_t
    value</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_set_multi_stream_2</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint16_t
    value</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_set_multi_stream_4</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint32_t
    value</var>, <var class="Fa">bus_size_t count</var>);</p>
<p class="Pp"><var class="Ft">void</var>
  <br/>
  <code class="Fn">bus_space_set_multi_stream_8</code>(<var class="Fa">bus_space_tag_t
    space</var>, <var class="Fa">bus_space_handle_t handle</var>,
    <var class="Fa">bus_size_t offset</var>, <var class="Fa">uint64_t
    value</var>, <var class="Fa">bus_size_t count</var>);</p>
</section>
<section class="Sh">
<h1 class="Sh" id="DESCRIPTION"><a class="permalink" href="#DESCRIPTION">DESCRIPTION</a></h1>
<p class="Pp">The <code class="Nm">bus_space</code> functions exist to allow
    device drivers machine-independent access to bus memory and register areas.
    All of the functions and types described in this document can be used by
    including the
    <code class="In">&lt;<a class="In">machine/bus.h</a>&gt;</code> header
  file.</p>
<p class="Pp">Many common devices are used on multiple architectures, but are
    accessed differently on each because of architectural constraints. For
    instance, a device which is mapped in one system's I/O space may be mapped
    in memory space on a second system. On a third system, architectural
    limitations might change the way registers need to be accessed (e.g.
    creating a non-linear register space). In some cases, a single driver may
    need to access the same type of device in multiple ways in a single system
    or architecture. The goal of the <code class="Nm">bus_space</code> functions
    is to allow a single driver source file to manipulate a set of devices on
    different system architectures, and to allow a single driver object file to
    manipulate a set of devices on multiple bus types on a single
  architecture.</p>
<p class="Pp">Not all buses have to implement all functions described in this
    document, though that is encouraged if the operations are logically
    supported by the bus. Unimplemented functions should cause compile-time
    errors if possible.</p>
<p class="Pp">All of the interface definitions described in this document are
    shown as function prototypes and discussed as if they were required to be
    functions. Implementations are encouraged to implement prototyped
    (type-checked) versions of these interfaces, but may implement them as
    macros if appropriate. Machine-dependent types, variables, and functions
    should be marked clearly in
    <code class="In">&lt;<a class="In">machine/bus.h</a>&gt;</code> to avoid
    confusion with the machine-independent types and functions, and, if
    possible, should be given names which make the machine-dependence clear.</p>
</section>
<section class="Sh">
<h1 class="Sh" id="CONCEPTS_AND_GUIDELINES"><a class="permalink" href="#CONCEPTS_AND_GUIDELINES">CONCEPTS
  AND GUIDELINES</a></h1>
<p class="Pp">Bus spaces are described by bus space tags, which can be created
    only by machine-dependent code. A given machine may have several different
    types of bus space (e.g. memory space and I/O space), and thus may provide
    multiple different bus space tags. Individual buses or devices on a machine
    may use more than one bus space tag. For instance, ISA devices are given an
    ISA memory space tag and an ISA I/O space tag. Architectures may have
    several different tags which represent the same type of space, for instance
    because of multiple different host bus interface chipsets.</p>
<p class="Pp">A range in bus space is described by a bus address and a bus size.
    The bus address describes the start of the range in bus space. The bus size
    describes the size of the range in bytes. Buses which are not byte
    addressable may require use of bus space ranges with appropriately aligned
    addresses and properly rounded sizes.</p>
<p class="Pp">Access to regions of bus space is facilitated by use of bus space
    handles, which are usually created by mapping a specific range of a bus
    space. Handles may also be created by allocating and mapping a range of bus
    space, the actual location of which is picked by the implementation within
    bounds specified by the caller of the allocation function.</p>
<p class="Pp">All of the bus space access functions require one bus space tag
    argument, at least one handle argument, and at least one offset argument (a
    bus size). The bus space tag specifies the space, each handle specifies a
    region in the space, and each offset specifies the offset into the region of
    the actual location(s) to be accessed. Offsets are given in bytes, though
    buses may impose alignment constraints. The offset used to access data
    relative to a given handle must be such that all of the data being accessed
    is in the mapped region that the handle describes. Trying to access data
    outside that region is an error.</p>
<p class="Pp">Because some architectures' memory systems use buffering to
    improve memory and device access performance, there is a mechanism which can
    be used to create &#x201C;barriers&#x201D; in the bus space read and write
    stream. There are three types of barriers: read, write, and read/write. All
    reads started to the region before a read barrier must complete before any
    reads after the read barrier are started. (The analogous requirement is true
    for write barriers.) Read/write barriers force all reads and writes started
    before the barrier to complete before any reads or writes after the barrier
    are started. Correctly-written drivers will include all appropriate
    barriers, and assume only the read/write ordering imposed by the barrier
    operations.</p>
<p class="Pp">People trying to write portable drivers with the
    <code class="Nm">bus_space</code> functions should try to make minimal
    assumptions about what the system allows. In particular, they should expect
    that the system requires bus space addresses being accessed to be naturally
    aligned (i.e., base address of handle added to offset is a multiple of the
    access size), and that the system does alignment checking on pointers (i.e.,
    pointer to objects being read and written must point to properly-aligned
    data).</p>
<p class="Pp">The descriptions of the <code class="Nm">bus_space</code>
    functions given below all assume that they are called with proper arguments.
    If called with invalid arguments or arguments that are out of range (e.g.
    trying to access data outside of the region mapped when a given handle was
    created), undefined behaviour results. In that case, they may cause the
    system to halt, either intentionally (via panic) or unintentionally (by
    causing a fatal trap of by some other means) or may cause improper operation
    which is not immediately fatal. Functions which return
    <var class="Ft">void</var> or which return data read from bus space (i.e.,
    functions which do not obviously return an error code) do not fail. They
    could only fail if given invalid arguments, and in that case their behaviour
    is undefined. Functions which take a count of bytes have undefined results
    if the specified <var class="Fa">count</var> is zero.</p>
</section>
<section class="Sh">
<h1 class="Sh" id="TYPES"><a class="permalink" href="#TYPES">TYPES</a></h1>
<p class="Pp">Several types are defined in
    <code class="In">&lt;<a class="In">machine/bus.h</a>&gt;</code> to
    facilitate use of the <code class="Nm">bus_space</code> functions by
    drivers.</p>
<section class="Ss">
<h2 class="Ss" id="bus_addr_t"><a class="permalink" href="#bus_addr_t"><var class="Vt">bus_addr_t</var></a></h2>
<p class="Pp">The <var class="Vt">bus_addr_t</var> type is used to describe bus
    addresses. It must be an unsigned integral type capable of holding the
    largest bus address usable by the architecture. This type is primarily used
    when mapping and unmapping bus space.</p>
</section>
<section class="Ss">
<h2 class="Ss" id="bus_size_t"><a class="permalink" href="#bus_size_t"><var class="Vt">bus_size_t</var></a></h2>
<p class="Pp">The <var class="Vt">bus_size_t</var> type is used to describe
    sizes of ranges in bus space. It must be an unsigned integral type capable
    of holding the size of the largest bus address range usable on the
    architecture. This type is used by virtually all of the
    <code class="Nm">bus_space</code> functions, describing sizes when mapping
    regions and offsets into regions when performing space access
  operations.</p>
</section>
<section class="Ss">
<h2 class="Ss" id="bus_space_tag_t"><a class="permalink" href="#bus_space_tag_t"><var class="Vt">bus_space_tag_t</var></a></h2>
<p class="Pp">The <var class="Vt">bus_space_tag_t</var> type is used to describe
    a particular bus space on a machine. Its contents are machine-dependent and
    should be considered opaque by machine-independent code. This type is used
    by all <code class="Nm">bus_space</code> functions to name the space on
    which they are operating.</p>
</section>
<section class="Ss">
<h2 class="Ss" id="bus_space_handle_t"><a class="permalink" href="#bus_space_handle_t"><var class="Vt">bus_space_handle_t</var></a></h2>
<p class="Pp">The <var class="Vt">bus_space_handle_t</var> type is used to
    describe a mapping of a range of bus space. Its contents are
    machine-dependent and should be considered opaque by machine-independent
    code. This type is used when performing bus space access operations.</p>
</section>
</section>
<section class="Sh">
<h1 class="Sh" id="MAPPING_AND_UNMAPPING_BUS_SPACE"><a class="permalink" href="#MAPPING_AND_UNMAPPING_BUS_SPACE">MAPPING
  AND UNMAPPING BUS SPACE</a></h1>
<p class="Pp">This section is specific to the <span class="Ux">NetBSD</span>
    version of these functions and may or may not apply to the
    <span class="Ux">FreeBSD</span> version.</p>
<p class="Pp" id="bus_space_map">Bus space must be mapped before it can be used,
    and should be unmapped when it is no longer needed. The
    <a class="permalink" href="#bus_space_map"><code class="Fn">bus_space_map</code></a>()
    and <code class="Fn">bus_space_unmap</code>() functions provide these
    capabilities.</p>
<p class="Pp" id="bus_space_subregion">Some drivers need to be able to pass a
    subregion of already-mapped bus space to another driver or module within a
    driver. The
    <a class="permalink" href="#bus_space_subregion"><code class="Fn">bus_space_subregion</code></a>()
    function allows such subregions to be created.</p>
<section class="Ss">
<h2 class="Ss" id="bus_space_map_space_address_size_flags_handlep"><a class="permalink" href="#bus_space_map_space_address_size_flags_handlep"><code class="Fn">bus_space_map</code>(<var class="Fa">space</var>,
  <var class="Fa">address</var>, <var class="Fa">size</var>,
  <var class="Fa">flags</var>, <var class="Fa">handlep</var>)</a></h2>
<p class="Pp">The <code class="Fn">bus_space_map</code>() function maps the
    region of bus space named by the <var class="Fa">space</var>,
    <var class="Fa">address</var>, and <var class="Fa">size</var> arguments. If
    successful, it returns zero and fills in the bus space handle pointed to by
    <var class="Fa">handlep</var> with the handle that can be used to access the
    mapped region. If unsuccessful, it will return non-zero and leave the bus
    space handle pointed to by <var class="Fa">handlep</var> in an undefined
    state.</p>
<p class="Pp">The <var class="Fa">flags</var> argument controls how the space is
    to be mapped. Supported flags include:</p>
<dl class="Bl-tag">
  <dt id="BUS_SPACE_MAP_CACHEABLE"><a class="permalink" href="#BUS_SPACE_MAP_CACHEABLE"><code class="Dv">BUS_SPACE_MAP_CACHEABLE</code></a></dt>
  <dd>Try to map the space so that accesses can be cached and/or prefetched by
      the system. If this flag is not specified, the implementation should map
      the space so that it will not be cached or prefetched.
    <p class="Pp">This flag must have a value of 1 on all implementations for
        backward compatibility.</p>
  </dd>
  <dt id="BUS_SPACE_MAP_LINEAR"><a class="permalink" href="#BUS_SPACE_MAP_LINEAR"><code class="Dv">BUS_SPACE_MAP_LINEAR</code></a></dt>
  <dd>Try to map the space so that its contents can be accessed linearly via
      normal memory access methods (e.g. pointer dereferencing and structure
      accesses). This is useful when software wants to do direct access to a
      memory device, e.g. a frame buffer. If this flag is specified and linear
      mapping is not possible, the
      <a class="permalink" href="#bus_space_map~2"><code class="Fn" id="bus_space_map~2">bus_space_map</code></a>()
      call should fail. If this flag is not specified, the system may map the
      space in whatever way is most convenient.</dd>
  <dt id="BUS_SPACE_MAP_NONPOSTED"><a class="permalink" href="#BUS_SPACE_MAP_NONPOSTED"><code class="Dv">BUS_SPACE_MAP_NONPOSTED</code></a></dt>
  <dd>Try to map the space using non-posted device memory. This is to support
      buses and devices where mapping with posted device memory is unsupported
      or broken. This flag is currently only available on arm64.</dd>
</dl>
<p class="Pp">Not all combinations of flags make sense or are supported with all
    spaces. For instance, <code class="Dv">BUS_SPACE_MAP_CACHEABLE</code> may be
    meaningless when used on many systems' I/O port spaces, and on some systems
    <code class="Dv">BUS_SPACE_MAP_LINEAR</code> without
    <code class="Dv">BUS_SPACE_MAP_CACHEABLE</code> may never work. When the
    system hardware or firmware provides hints as to how spaces should be mapped
    (e.g. the PCI memory mapping registers' &#x201C;prefetchable&#x201D; bit),
    those hints should be followed for maximum compatibility. On some systems,
    requesting a mapping that cannot be satisfied (e.g. requesting a
    non-cacheable mapping when the system can only provide a cacheable one) will
    cause the request to fail.</p>
<p class="Pp">Some implementations may keep track of use of bus space for some
    or all bus spaces and refuse to allow duplicate allocations. This is
    encouraged for bus spaces which have no notion of slot-specific space
    addressing, such as ISA, and for spaces which coexist with those spaces
    (e.g. PCI memory and I/O spaces co-existing with ISA memory and I/O
  spaces).</p>
<p class="Pp">Mapped regions may contain areas for which there is no device on
    the bus. If space in those areas is accessed, the results are
  bus-dependent.</p>
</section>
<section class="Ss">
<h2 class="Ss" id="bus_space_unmap_space_handle_size"><a class="permalink" href="#bus_space_unmap_space_handle_size"><a class="permalink" href="#bus_space_unmap"><code class="Fn" id="bus_space_unmap">bus_space_unmap</code></a>(<var class="Fa">space</var>,
  <var class="Fa">handle</var>, <var class="Fa">size</var>)</a></h2>
<p class="Pp">The <code class="Fn">bus_space_unmap</code>() function unmaps a
    region of bus space mapped with <code class="Fn">bus_space_map</code>().
    When unmapping a region, the <var class="Fa">size</var> specified should be
    the same as the size given to <code class="Fn">bus_space_map</code>() when
    mapping that region.</p>
<p class="Pp" id="bus_space_unmap~2">After
    <a class="permalink" href="#bus_space_unmap~2"><code class="Fn">bus_space_unmap</code></a>()
    is called on a handle, that handle is no longer valid. (If copies were made
    of the handle they are no longer valid, either.)</p>
<p class="Pp" id="bus_space_unmap~3">This function will never fail. If it would
    fail (e.g. because of an argument error), that indicates a software bug
    which should cause a panic. In that case,
    <a class="permalink" href="#bus_space_unmap~3"><code class="Fn">bus_space_unmap</code></a>()
    will never return.</p>
</section>
<section class="Ss">
<h2 class="Ss" id="bus_space_subregion_space_handle_offset_size_nhandlep"><a class="permalink" href="#bus_space_subregion_space_handle_offset_size_nhandlep"><code class="Fn">bus_space_subregion</code>(<var class="Fa">space</var>,
  <var class="Fa">handle</var>, <var class="Fa">offset</var>,
  <var class="Fa">size</var>, <var class="Fa">nhandlep</var>)</a></h2>
<p class="Pp">The <code class="Fn">bus_space_subregion</code>() function is a
    convenience function which makes a new handle to some subregion of an
    already-mapped region of bus space. The subregion described by the new
    handle starts at byte offset <var class="Fa">offset</var> into the region
    described by <var class="Fa">handle</var>, with the size give by
    <var class="Fa">size</var>, and must be wholly contained within the original
    region.</p>
<p class="Pp" id="bus_space_subregion~2">If successful,
    <a class="permalink" href="#bus_space_subregion~2"><code class="Fn">bus_space_subregion</code></a>()
    returns zero and fills in the bus space handle pointed to by
    <var class="Fa">nhandlep</var>. If unsuccessful, it returns non-zero and
    leaves the bus space handle pointed to by <var class="Fa">nhandlep</var> in
    an undefined state. In either case, the handle described by
    <var class="Fa">handle</var> remains valid and is unmodified.</p>
<p class="Pp" id="bus_space_subregion~3">When done with a handle created by
    <a class="permalink" href="#bus_space_subregion~3"><code class="Fn">bus_space_subregion</code></a>(),
    the handle should be thrown away. Under no circumstances should
    <code class="Fn">bus_space_unmap</code>() be used on the handle. Doing so
    may confuse any resource management being done on the space, and will result
    in undefined behaviour. When <code class="Fn">bus_space_unmap</code>() or
    <code class="Fn">bus_space_free</code>() is called on a handle, all
    subregions of that handle become invalid.</p>
</section>
</section>
<section class="Sh">
<h1 class="Sh" id="ALLOCATING_AND_FREEING_BUS_SPACE"><a class="permalink" href="#ALLOCATING_AND_FREEING_BUS_SPACE">ALLOCATING
  AND FREEING BUS SPACE</a></h1>
<p class="Pp">This section is specific to the <span class="Ux">NetBSD</span>
    version of these functions and may or may not apply to the
    <span class="Ux">FreeBSD</span> version.</p>
<p class="Pp" id="bus_space_alloc">Some devices require or allow bus space to be
    allocated by the operating system for device use. When the devices no longer
    need the space, the operating system should free it for use by other
    devices. The
    <a class="permalink" href="#bus_space_alloc"><code class="Fn">bus_space_alloc</code></a>()
    and <code class="Fn">bus_space_free</code>() functions provide these
    capabilities.</p>
<section class="Ss">
<h2 class="Ss" id="bus_space_alloc_space_reg_start_reg_end_size_alignment_boundary_flags_addrp_handlep"><a class="permalink" href="#bus_space_alloc_space_reg_start_reg_end_size_alignment_boundary_flags_addrp_handlep"><code class="Fn">bus_space_alloc</code>(<var class="Fa">space</var>,
  <var class="Fa">reg_start</var>, <var class="Fa">reg_end</var>,
  <var class="Fa">size</var>, <var class="Fa">alignment</var>,
  <var class="Fa">boundary</var>, <var class="Fa">flags</var>,
  <var class="Fa">addrp</var>, <var class="Fa">handlep</var>)</a></h2>
<p class="Pp">The <code class="Fn">bus_space_alloc</code>() function allocates
    and maps a region of bus space with the size given by
    <var class="Fa">size</var>, corresponding to the given constraints. If
    successful, it returns zero, fills in the bus address pointed to by
    <var class="Fa">addrp</var> with the bus space address of the allocated
    region, and fills in the bus space handle pointed to by
    <var class="Fa">handlep</var> with the handle that can be used to access
    that region. If unsuccessful, it returns non-zero and leaves the bus address
    pointed to by <var class="Fa">addrp</var> and the bus space handle pointed
    to by <var class="Fa">handlep</var> in an undefined state.</p>
<p class="Pp" id="bus_space_alloc~2">Constraints on the allocation are given by
    the <var class="Fa">reg_start</var>, <var class="Fa">reg_end</var>,
    <var class="Fa">alignment</var>, and <var class="Fa">boundary</var>
    parameters. The allocated region will start at or after
    <var class="Fa">reg_start</var> and end before or at
    <var class="Fa">reg_end</var>. The <var class="Fa">alignment</var>
    constraint must be a power of two, and the allocated region will start at an
    address that is an even multiple of that power of two. The
    <var class="Fa">boundary</var> constraint, if non-zero, ensures that the
    region is allocated so that <var class="Fa">first address in region</var> /
    <var class="Fa">boundary</var> has the same value as <var class="Fa">last
    address in region</var> / <var class="Fa">boundary</var>. If the constraints
    cannot be met,
    <a class="permalink" href="#bus_space_alloc~2"><code class="Fn">bus_space_alloc</code></a>()
    will fail. It is an error to specify a set of constraints that can never be
    met (for example, <var class="Fa">size</var> greater than
    <var class="Fa">boundary</var>).</p>
<p class="Pp" id="bus_space_map~3">The <var class="Fa">flags</var> parameter is
    the same as the like-named parameter to
    <a class="permalink" href="#bus_space_map~3"><code class="Fn">bus_space_map</code></a>(),
    the same flag values should be used, and they have the same meanings.</p>
<p class="Pp" id="bus_space_alloc~3">Handles created by
    <a class="permalink" href="#bus_space_alloc~3"><code class="Fn">bus_space_alloc</code></a>()
    should only be freed with <code class="Fn">bus_space_free</code>(). Trying
    to use <code class="Fn">bus_space_unmap</code>() on them causes undefined
    behaviour. The <code class="Fn">bus_space_subregion</code>() function can be
    used on handles created by <code class="Fn">bus_space_alloc</code>().</p>
</section>
<section class="Ss">
<h2 class="Ss" id="bus_space_free_space_handle_size"><a class="permalink" href="#bus_space_free_space_handle_size"><code class="Fn">bus_space_free</code>(<var class="Fa">space</var>,
  <var class="Fa">handle</var>, <var class="Fa">size</var>)</a></h2>
<p class="Pp">The <code class="Fn">bus_space_free</code>() function unmaps and
    frees a region of bus space mapped and allocated with
    <code class="Fn">bus_space_alloc</code>(). When unmapping a region, the
    <var class="Fa">size</var> specified should be the same as the size given to
    <code class="Fn">bus_space_alloc</code>() when allocating the region.</p>
<p class="Pp" id="bus_space_free">After
    <a class="permalink" href="#bus_space_free"><code class="Fn">bus_space_free</code></a>()
    is called on a handle, that handle is no longer valid. (If copies were made
    of the handle, they are no longer valid, either.)</p>
<p class="Pp" id="bus_space_free~2">This function will never fail. If it would
    fail (e.g. because of an argument error), that indicates a software bug
    which should cause a panic. In that case,
    <a class="permalink" href="#bus_space_free~2"><code class="Fn">bus_space_free</code></a>()
    will never return.</p>
</section>
</section>
<section class="Sh">
<h1 class="Sh" id="READING_AND_WRITING_SINGLE_DATA_ITEMS"><a class="permalink" href="#READING_AND_WRITING_SINGLE_DATA_ITEMS">READING
  AND WRITING SINGLE DATA ITEMS</a></h1>
<p class="Pp">The simplest way to access bus space is to read or write a single
    data item. The <code class="Fn">bus_space_read_N</code>() and
    <code class="Fn">bus_space_write_N</code>() families of functions provide
    the ability to read and write 1, 2, 4, and 8 byte data items on buses which
    support those access sizes.</p>
<section class="Ss">
<h2 class="Ss" id="bus_space_read_1_space_handle_offset"><a class="permalink" href="#bus_space_read_1_space_handle_offset"><a class="permalink" href="#bus_space_read_1"><code class="Fn" id="bus_space_read_1">bus_space_read_1</code></a>(<var class="Fa">space</var>,
  <var class="Fa">handle</var>, <var class="Fa">offset</var>)</a></h2>
</section>
<section class="Ss">
<h2 class="Ss" id="bus_space_read_2_space_handle_offset"><a class="permalink" href="#bus_space_read_2_space_handle_offset"><a class="permalink" href="#bus_space_read_2"><code class="Fn" id="bus_space_read_2">bus_space_read_2</code></a>(<var class="Fa">space</var>,
  <var class="Fa">handle</var>, <var class="Fa">offset</var>)</a></h2>
</section>
<section class="Ss">
<h2 class="Ss" id="bus_space_read_4_space_handle_offset"><a class="permalink" href="#bus_space_read_4_space_handle_offset"><a class="permalink" href="#bus_space_read_4"><code class="Fn" id="bus_space_read_4">bus_space_read_4</code></a>(<var class="Fa">space</var>,
  <var class="Fa">handle</var>, <var class="Fa">offset</var>)</a></h2>
</section>
<section class="Ss">
<h2 class="Ss" id="bus_space_read_8_space_handle_offset"><a class="permalink" href="#bus_space_read_8_space_handle_offset"><a class="permalink" href="#bus_space_read_8"><code class="Fn" id="bus_space_read_8">bus_space_read_8</code></a>(<var class="Fa">space</var>,
  <var class="Fa">handle</var>, <var class="Fa">offset</var>)</a></h2>
<p class="Pp">The <code class="Fn">bus_space_read_N</code>() family of functions
    reads a 1, 2, 4, or 8 byte data item from the offset specified by
    <var class="Fa">offset</var> into the region specified by
    <var class="Fa">handle</var> of the bus space specified by
    <var class="Fa">space</var>. The location being read must lie within the bus
    space region specified by <var class="Fa">handle</var>.</p>
<p class="Pp">For portability, the starting address of the region specified by
    <var class="Fa">handle</var> plus the offset should be a multiple of the
    size of data item being read. On some systems, not obeying this requirement
    may cause incorrect data to be read, on others it may cause a system
  crash.</p>
<p class="Pp" id="bus_space_read_N">Read operations done by the
    <a class="permalink" href="#bus_space_read_N"><code class="Fn">bus_space_read_N</code></a>()
    functions may be executed out of order with respect to other pending read
    and write operations unless order is enforced by use of the
    <code class="Fn">bus_space_barrier</code>() function.</p>
<p class="Pp">These functions will never fail. If they would fail (e.g. because
    of an argument error), that indicates a software bug which should cause a
    panic. In that case, they will never return.</p>
</section>
<section class="Ss">
<h2 class="Ss" id="bus_space_write_1_space_handle_offset_value"><a class="permalink" href="#bus_space_write_1_space_handle_offset_value"><a class="permalink" href="#bus_space_write_1"><code class="Fn" id="bus_space_write_1">bus_space_write_1</code></a>(<var class="Fa">space</var>,
  <var class="Fa">handle</var>, <var class="Fa">offset</var>,
  <var class="Fa">value</var>)</a></h2>
</section>
<section class="Ss">
<h2 class="Ss" id="bus_space_write_2_space_handle_offset_value"><a class="permalink" href="#bus_space_write_2_space_handle_offset_value"><a class="permalink" href="#bus_space_write_2"><code class="Fn" id="bus_space_write_2">bus_space_write_2</code></a>(<var class="Fa">space</var>,
  <var class="Fa">handle</var>, <var class="Fa">offset</var>,
  <var class="Fa">value</var>)</a></h2>
</section>
<section class="Ss">
<h2 class="Ss" id="bus_space_write_4_space_handle_offset_value"><a class="permalink" href="#bus_space_write_4_space_handle_offset_value"><a class="permalink" href="#bus_space_write_4"><code class="Fn" id="bus_space_write_4">bus_space_write_4</code></a>(<var class="Fa">space</var>,
  <var class="Fa">handle</var>, <var class="Fa">offset</var>,
  <var class="Fa">value</var>)</a></h2>
</section>
<section class="Ss">
<h2 class="Ss" id="bus_space_write_8_space_handle_offset_value"><a class="permalink" href="#bus_space_write_8_space_handle_offset_value"><a class="permalink" href="#bus_space_write_8"><code class="Fn" id="bus_space_write_8">bus_space_write_8</code></a>(<var class="Fa">space</var>,
  <var class="Fa">handle</var>, <var class="Fa">offset</var>,
  <var class="Fa">value</var>)</a></h2>
<p class="Pp">The <code class="Fn">bus_space_write_N</code>() family of
    functions writes a 1, 2, 4, or 8 byte data item to the offset specified by
    <var class="Fa">offset</var> into the region specified by
    <var class="Fa">handle</var> of the bus space specified by
    <var class="Fa">space</var>. The location being written must lie within the
    bus space region specified by <var class="Fa">handle</var>.</p>
<p class="Pp">For portability, the starting address of the region specified by
    <var class="Fa">handle</var> plus the offset should be a multiple of the
    size of data item being written. On some systems, not obeying this
    requirement may cause incorrect data to be written, on others it may cause a
    system crash.</p>
<p class="Pp" id="bus_space_write_N">Write operations done by the
    <a class="permalink" href="#bus_space_write_N"><code class="Fn">bus_space_write_N</code></a>()
    functions may be executed out of order with respect to other pending read
    and write operations unless order is enforced by use of the
    <code class="Fn">bus_space_barrier</code>() function.</p>
<p class="Pp">These functions will never fail. If they would fail (e.g. because
    of an argument error), that indicates a software bug which should cause a
    panic. In that case, they will never return.</p>
</section>
</section>
<section class="Sh">
<h1 class="Sh" id="PROBING_BUS_SPACE_FOR_HARDWARE_WHICH_MAY_NOT_RESPOND"><a class="permalink" href="#PROBING_BUS_SPACE_FOR_HARDWARE_WHICH_MAY_NOT_RESPOND">PROBING
  BUS SPACE FOR HARDWARE WHICH MAY NOT RESPOND</a></h1>
<p class="Pp">One problem with the
    <a class="permalink" href="#bus_space_read_N~2"><code class="Fn" id="bus_space_read_N~2">bus_space_read_N</code></a>()
    and <code class="Fn">bus_space_write_N</code>() family of functions is that
    they provide no protection against exceptions which can occur when no
    physical hardware or device responds to the read or write cycles. In such a
    situation, the system typically would panic due to a kernel-mode bus error.
    The <code class="Fn">bus_space_peek_N</code>() and
    <code class="Fn">bus_space_poke_N</code>() family of functions provide a
    mechanism to handle these exceptions gracefully without the risk of crashing
    the system.</p>
<p class="Pp" id="bus_space_read_N~3">As with
    <a class="permalink" href="#bus_space_read_N~3"><code class="Fn">bus_space_read_N</code></a>()
    and <code class="Fn">bus_space_write_N</code>(), the peek and poke functions
    provide the ability to read and write 1, 2, 4, and 8 byte data items on
    busses which support those access sizes. All of the constraints specified in
    the descriptions of the <code class="Fn">bus_space_read_N</code>() and
    <code class="Fn">bus_space_write_N</code>() functions also apply to
    <code class="Fn">bus_space_peek_N</code>() and
    <code class="Fn">bus_space_poke_N</code>().</p>
<p class="Pp" id="bus_space_barrier">In addition, explicit calls to the
    <a class="permalink" href="#bus_space_barrier"><code class="Fn">bus_space_barrier</code></a>()
    function are not required as the implementation will ensure all pending
    operations complete before the peek or poke operation starts. The
    implementation will also ensure that the peek or poke operations complete
    before returning.</p>
<p class="Pp" id="bus_space_peek_N">The return value indicates the outcome of
    the peek or poke operation. A return value of zero implies that a hardware
    device is responding to the operation at the specified offset in the bus
    space. A non-zero return value indicates that the kernel intercepted a
    hardware exception (e.g., bus error) when the peek or poke operation was
    attempted. Note that some busses are incapable of generating exceptions when
    non-existent hardware is accessed. In such cases, these functions will
    always return zero and the value of the data read by
    <a class="permalink" href="#bus_space_peek_N"><code class="Fn">bus_space_peek_N</code></a>()
    will be unspecified.</p>
<p class="Pp" id="bus_space_peek_N~2">Finally, it should be noted that at this
    time the
    <a class="permalink" href="#bus_space_peek_N~2"><code class="Fn">bus_space_peek_N</code></a>()
    and <code class="Fn">bus_space_poke_N</code>() functions are not re-entrant
    and should not, therefore, be used from within an interrupt service routine.
    This constraint may be removed at some point in the future.</p>
<p class="Pp"></p>
<dl class="Bl-ohang Bl-compact">
  <dt id="bus_space_peek_1"><a class="permalink" href="#bus_space_peek_1"><code class="Fn">bus_space_peek_1</code></a>(<var class="Fa">space</var>,
    <var class="Fa">handle</var>, <var class="Fa">offset</var>,
    <var class="Fa">datap</var>)</dt>
  <dd></dd>
  <dt id="bus_space_peek_2"><a class="permalink" href="#bus_space_peek_2"><code class="Fn">bus_space_peek_2</code></a>(<var class="Fa">space</var>,
    <var class="Fa">handle</var>, <var class="Fa">offset</var>,
    <var class="Fa">datap</var>)</dt>
  <dd></dd>
  <dt id="bus_space_peek_4"><a class="permalink" href="#bus_space_peek_4"><code class="Fn">bus_space_peek_4</code></a>(<var class="Fa">space</var>,
    <var class="Fa">handle</var>, <var class="Fa">offset</var>,
    <var class="Fa">datap</var>)</dt>
  <dd></dd>
  <dt id="bus_space_peek_8"><a class="permalink" href="#bus_space_peek_8"><code class="Fn">bus_space_peek_8</code></a>(<var class="Fa">space</var>,
    <var class="Fa">handle</var>, <var class="Fa">offset</var>,
    <var class="Fa">datap</var>)</dt>
  <dd>
    <p class="Pp" id="bus_space_peek_N~3">The
        <a class="permalink" href="#bus_space_peek_N~3"><code class="Fn">bus_space_peek_N</code></a>()
        family of functions cautiously read a 1, 2, 4, or 8 byte data item from
        the offset specified by <var class="Fa">offset</var> in the region
        specified by <var class="Fa">handle</var> of the bus space specified by
        <var class="Fa">space</var>. The data item read is stored in the
        location pointed to by <var class="Fa">datap</var>. It is permissible
        for <var class="Fa">datap</var> to be NULL, in which case the data item
        will be discarded after being read.</p>
    <p class="Pp"></p>
  </dd>
  <dt id="bus_space_poke_1"><a class="permalink" href="#bus_space_poke_1"><code class="Fn">bus_space_poke_1</code></a>(<var class="Fa">space</var>,
    <var class="Fa">handle</var>, <var class="Fa">offset</var>,
    <var class="Fa">value</var>)</dt>
  <dd></dd>
  <dt id="bus_space_poke_2"><a class="permalink" href="#bus_space_poke_2"><code class="Fn">bus_space_poke_2</code></a>(<var class="Fa">space</var>,
    <var class="Fa">handle</var>, <var class="Fa">offset</var>,
    <var class="Fa">value</var>)</dt>
  <dd></dd>
  <dt id="bus_space_poke_4"><a class="permalink" href="#bus_space_poke_4"><code class="Fn">bus_space_poke_4</code></a>(<var class="Fa">space</var>,
    <var class="Fa">handle</var>, <var class="Fa">offset</var>,
    <var class="Fa">value</var>)</dt>
  <dd></dd>
  <dt id="bus_space_poke_8"><a class="permalink" href="#bus_space_poke_8"><code class="Fn">bus_space_poke_8</code></a>(<var class="Fa">space</var>,
    <var class="Fa">handle</var>, <var class="Fa">offset</var>,
    <var class="Fa">value</var>)</dt>
  <dd>
    <p class="Pp" id="bus_space_poke_N">The
        <a class="permalink" href="#bus_space_poke_N"><code class="Fn">bus_space_poke_N</code></a>()
        family of functions cautiously write a 1, 2, 4, or 8 byte data item
        specified by <var class="Fa">value</var> to the offset specified by
        <var class="Fa">offset</var> in the region specified by
        <var class="Fa">handle</var> of the bus space specified by
        <var class="Fa">space</var>.</p>
  </dd>
</dl>
</section>
<section class="Sh">
<h1 class="Sh" id="BARRIERS"><a class="permalink" href="#BARRIERS">BARRIERS</a></h1>
<p class="Pp">In order to allow high-performance buffering implementations to
    avoid bus activity on every operation, read and write ordering should be
    specified explicitly by drivers when necessary. The
    <code class="Fn">bus_space_barrier</code>() function provides that
  ability.</p>
<section class="Ss">
<h2 class="Ss" id="bus_space_barrier_space_handle_offset_length_flags"><a class="permalink" href="#bus_space_barrier_space_handle_offset_length_flags"><code class="Fn">bus_space_barrier</code>(<var class="Fa">space</var>,
  <var class="Fa">handle</var>, <var class="Fa">offset</var>,
  <var class="Fa">length</var>, <var class="Fa">flags</var>)</a></h2>
<p class="Pp">The <code class="Fn">bus_space_barrier</code>() function enforces
    ordering of bus space read and write operations for the specified subregion
    (described by the <var class="Fa">offset</var> and
    <var class="Fa">length</var> parameters) of the region named by
    <var class="Fa">handle</var> in the space named by
    <var class="Fa">space</var>.</p>
<p class="Pp">The <var class="Fa">flags</var> argument controls what types of
    operations are to be ordered. Supported flags are:</p>
<dl class="Bl-tag">
  <dt id="BUS_SPACE_BARRIER_READ"><a class="permalink" href="#BUS_SPACE_BARRIER_READ"><code class="Dv">BUS_SPACE_BARRIER_READ</code></a></dt>
  <dd>Synchronize read operations.</dd>
  <dt id="BUS_SPACE_BARRIER_WRITE"><a class="permalink" href="#BUS_SPACE_BARRIER_WRITE"><code class="Dv">BUS_SPACE_BARRIER_WRITE</code></a></dt>
  <dd>Synchronize write operations.</dd>
</dl>
<p class="Pp">Those flags can be combined (or-ed together) to enforce ordering
    on both read and write operations.</p>
<p class="Pp">All of the specified type(s) of operation which are done to the
    region before the barrier operation are guaranteed to complete before any of
    the specified type(s) of operation done after the barrier.</p>
<p class="Pp">Example: Consider a hypothetical device with two single-byte
    ports, one write-only input port (at offset 0) and a read-only output port
    (at offset 1). Operation of the device is as follows: data bytes are written
    to the input port, and are placed by the device on a stack, the top of which
    is read by reading from the output port. The sequence to correctly write two
    data bytes to the device then read those two data bytes back would be:</p>
<div class="Bd Pp Li">
<pre>/*
 * t and h are the tag and handle for the mapped device's
 * space.
 */
bus_space_write_1(t, h, 0, data0);
bus_space_barrier(t, h, 0, 1, BUS_SPACE_BARRIER_WRITE);  /* 1 */
bus_space_write_1(t, h, 0, data1);
bus_space_barrier(t, h, 0, 2,
    BUS_SPACE_BARRIER_READ|BUS_SPACE_BARRIER_WRITE);     /* 2 */
ndata1 = bus_space_read_1(t, h, 1);
bus_space_barrier(t, h, 1, 1, BUS_SPACE_BARRIER_READ);   /* 3 */
ndata0 = bus_space_read_1(t, h, 1);
/* data0 == ndata0, data1 == ndata1 */</pre>
</div>
<p class="Pp">The first barrier makes sure that the first write finishes before
    the second write is issued, so that two writes to the input port are done in
    order and are not collapsed into a single write. This ensures that the data
    bytes are written to the device correctly and in order.</p>
<p class="Pp">The second barrier makes sure that the writes to the output port
    finish before any of the reads to the input port are issued, thereby making
    sure that all of the writes are finished before data is read. This ensures
    that the first byte read from the device really is the last one that was
    written.</p>
<p class="Pp">The third barrier makes sure that the first read finishes before
    the second read is issued, ensuring that data is read correctly and in
    order.</p>
<p class="Pp">The barriers in the example above are specified to cover the
    absolute minimum number of bus space locations. It is correct (and often
    easier) to make barrier operations cover the device's whole range of bus
    space, that is, to specify an offset of zero and the size of the whole
    region.</p>
</section>
</section>
<section class="Sh">
<h1 class="Sh" id="REGION_OPERATIONS"><a class="permalink" href="#REGION_OPERATIONS">REGION
  OPERATIONS</a></h1>
<p class="Pp">Some devices use buffers which are mapped as regions in bus space.
    Often, drivers want to copy the contents of those buffers to or from memory,
    e.g. into mbufs which can be passed to higher levels of the system or from
    mbufs to be output to a network. In order to allow drivers to do this as
    efficiently as possible, the
    <a class="permalink" href="#bus_space_read_region_N"><code class="Fn" id="bus_space_read_region_N">bus_space_read_region_N</code></a>()
    and <code class="Fn">bus_space_write_region_N</code>() families of functions
    are provided.</p>
<p class="Pp" id="bus_space_copy_region_N">Drivers occasionally need to copy one
    region of a bus space to another, or to set all locations in a region of bus
    space to contain a single value. The
    <a class="permalink" href="#bus_space_copy_region_N"><code class="Fn">bus_space_copy_region_N</code></a>()
    family of functions and the <code class="Fn">bus_space_set_region_N</code>()
    family of functions allow drivers to perform these operations.</p>
<section class="Ss">
<h2 class="Ss" id="bus_space_read_region_1_space_handle_offset_datap_count"><a class="permalink" href="#bus_space_read_region_1_space_handle_offset_datap_count"><a class="permalink" href="#bus_space_read_region_1"><code class="Fn" id="bus_space_read_region_1">bus_space_read_region_1</code></a>(<var class="Fa">space</var>,
  <var class="Fa">handle</var>, <var class="Fa">offset</var>,
  <var class="Fa">datap</var>, <var class="Fa">count</var>)</a></h2>
</section>
<section class="Ss">
<h2 class="Ss" id="bus_space_read_region_2_space_handle_offset_datap_count"><a class="permalink" href="#bus_space_read_region_2_space_handle_offset_datap_count"><a class="permalink" href="#bus_space_read_region_2"><code class="Fn" id="bus_space_read_region_2">bus_space_read_region_2</code></a>(<var class="Fa">space</var>,
  <var class="Fa">handle</var>, <var class="Fa">offset</var>,
  <var class="Fa">datap</var>, <var class="Fa">count</var>)</a></h2>
</section>
<section class="Ss">
<h2 class="Ss" id="bus_space_read_region_4_space_handle_offset_datap_count"><a class="permalink" href="#bus_space_read_region_4_space_handle_offset_datap_count"><a class="permalink" href="#bus_space_read_region_4"><code class="Fn" id="bus_space_read_region_4">bus_space_read_region_4</code></a>(<var class="Fa">space</var>,
  <var class="Fa">handle</var>, <var class="Fa">offset</var>,
  <var class="Fa">datap</var>, <var class="Fa">count</var>)</a></h2>
</section>
<section class="Ss">
<h2 class="Ss" id="bus_space_read_region_8_space_handle_offset_datap_count"><a class="permalink" href="#bus_space_read_region_8_space_handle_offset_datap_count"><a class="permalink" href="#bus_space_read_region_8"><code class="Fn" id="bus_space_read_region_8">bus_space_read_region_8</code></a>(<var class="Fa">space</var>,
  <var class="Fa">handle</var>, <var class="Fa">offset</var>,
  <var class="Fa">datap</var>, <var class="Fa">count</var>)</a></h2>
<p class="Pp">The <code class="Fn">bus_space_read_region_N</code>() family of
    functions reads <var class="Fa">count</var> 1, 2, 4, or 8 byte data items
    from bus space starting at byte offset <var class="Fa">offset</var> in the
    region specified by <var class="Fa">handle</var> of the bus space specified
    by <var class="Fa">space</var> and writes them into the array specified by
    <var class="Fa">datap</var>. Each successive data item is read from an
    offset 1, 2, 4, or 8 bytes after the previous data item (depending on which
    function is used). All locations being read must lie within the bus space
    region specified by <var class="Fa">handle</var>.</p>
<p class="Pp">For portability, the starting address of the region specified by
    <var class="Fa">handle</var> plus the offset should be a multiple of the
    size of data items being read and the data array pointer should be properly
    aligned. On some systems, not obeying these requirements may cause incorrect
    data to be read, on others it may cause a system crash.</p>
<p class="Pp" id="bus_space_read_region_N~2">Read operations done by the
    <a class="permalink" href="#bus_space_read_region_N~2"><code class="Fn">bus_space_read_region_N</code></a>()
    functions may be executed in any order. They may also be executed out of
    order with respect to other pending read and write operations unless order
    is enforced by use of the <code class="Fn">bus_space_barrier</code>()
    function. There is no way to insert barriers between reads of individual bus
    space locations executed by the
    <code class="Fn">bus_space_read_region_N</code>() functions.</p>
<p class="Pp">These functions will never fail. If they would fail (e.g. because
    of an argument error), that indicates a software bug which should cause a
    panic. In that case, they will never return.</p>
</section>
<section class="Ss">
<h2 class="Ss" id="bus_space_write_region_1_space_handle_offset_datap_count"><a class="permalink" href="#bus_space_write_region_1_space_handle_offset_datap_count"><a class="permalink" href="#bus_space_write_region_1"><code class="Fn" id="bus_space_write_region_1">bus_space_write_region_1</code></a>(<var class="Fa">space</var>,
  <var class="Fa">handle</var>, <var class="Fa">offset</var>,
  <var class="Fa">datap</var>, <var class="Fa">count</var>)</a></h2>
</section>
<section class="Ss">
<h2 class="Ss" id="bus_space_write_region_2_space_handle_offset_datap_count"><a class="permalink" href="#bus_space_write_region_2_space_handle_offset_datap_count"><a class="permalink" href="#bus_space_write_region_2"><code class="Fn" id="bus_space_write_region_2">bus_space_write_region_2</code></a>(<var class="Fa">space</var>,
  <var class="Fa">handle</var>, <var class="Fa">offset</var>,
  <var class="Fa">datap</var>, <var class="Fa">count</var>)</a></h2>
</section>
<section class="Ss">
<h2 class="Ss" id="bus_space_write_region_4_space_handle_offset_datap_count"><a class="permalink" href="#bus_space_write_region_4_space_handle_offset_datap_count"><a class="permalink" href="#bus_space_write_region_4"><code class="Fn" id="bus_space_write_region_4">bus_space_write_region_4</code></a>(<var class="Fa">space</var>,
  <var class="Fa">handle</var>, <var class="Fa">offset</var>,
  <var class="Fa">datap</var>, <var class="Fa">count</var>)</a></h2>
</section>
<section class="Ss">
<h2 class="Ss" id="bus_space_write_region_8_space_handle_offset_datap_count"><a class="permalink" href="#bus_space_write_region_8_space_handle_offset_datap_count"><a class="permalink" href="#bus_space_write_region_8"><code class="Fn" id="bus_space_write_region_8">bus_space_write_region_8</code></a>(<var class="Fa">space</var>,
  <var class="Fa">handle</var>, <var class="Fa">offset</var>,
  <var class="Fa">datap</var>, <var class="Fa">count</var>)</a></h2>
<p class="Pp">The <code class="Fn">bus_space_write_region_N</code>() family of
    functions reads <var class="Fa">count</var> 1, 2, 4, or 8 byte data items
    from the array specified by <var class="Fa">datap</var> and writes them to
    bus space starting at byte offset <var class="Fa">offset</var> in the region
    specified by <var class="Fa">handle</var> of the bus space specified by
    <var class="Fa">space</var>. Each successive data item is written to an
    offset 1, 2, 4, or 8 bytes after the previous data item (depending on which
    function is used). All locations being written must lie within the bus space
    region specified by <var class="Fa">handle</var>.</p>
<p class="Pp">For portability, the starting address of the region specified by
    <var class="Fa">handle</var> plus the offset should be a multiple of the
    size of data items being written and the data array pointer should be
    properly aligned. On some systems, not obeying these requirements may cause
    incorrect data to be written, on others it may cause a system crash.</p>
<p class="Pp" id="bus_space_write_region_N">Write operations done by the
    <a class="permalink" href="#bus_space_write_region_N"><code class="Fn">bus_space_write_region_N</code></a>()
    functions may be executed in any order. They may also be executed out of
    order with respect to other pending read and write operations unless order
    is enforced by use of the <code class="Fn">bus_space_barrier</code>()
    function. There is no way to insert barriers between writes of individual
    bus space locations executed by the
    <code class="Fn">bus_space_write_region_N</code>() functions.</p>
<p class="Pp">These functions will never fail. If they would fail (e.g. because
    of an argument error), that indicates a software bug which should cause a
    panic. In that case, they will never return.</p>
</section>
<section class="Ss">
<h2 class="Ss" id="bus_space_copy_region_1_space_srchandle_srcoffset_dsthandle_dstoffset_count"><a class="permalink" href="#bus_space_copy_region_1_space_srchandle_srcoffset_dsthandle_dstoffset_count"><a class="permalink" href="#bus_space_copy_region_1"><code class="Fn" id="bus_space_copy_region_1">bus_space_copy_region_1</code></a>(<var class="Fa">space</var>,
  <var class="Fa">srchandle</var>, <var class="Fa">srcoffset</var>,
  <var class="Fa">dsthandle</var>, <var class="Fa">dstoffset</var>,
  <var class="Fa">count</var>)</a></h2>
</section>
<section class="Ss">
<h2 class="Ss" id="bus_space_copy_region_2_space_srchandle_srcoffset_dsthandle_dstoffset_count"><a class="permalink" href="#bus_space_copy_region_2_space_srchandle_srcoffset_dsthandle_dstoffset_count"><a class="permalink" href="#bus_space_copy_region_2"><code class="Fn" id="bus_space_copy_region_2">bus_space_copy_region_2</code></a>(<var class="Fa">space</var>,
  <var class="Fa">srchandle</var>, <var class="Fa">srcoffset</var>,
  <var class="Fa">dsthandle</var>, <var class="Fa">dstoffset</var>,
  <var class="Fa">count</var>)</a></h2>
</section>
<section class="Ss">
<h2 class="Ss" id="bus_space_copy_region_4_space_srchandle_srcoffset_dsthandle_dstoffset_count"><a class="permalink" href="#bus_space_copy_region_4_space_srchandle_srcoffset_dsthandle_dstoffset_count"><a class="permalink" href="#bus_space_copy_region_4"><code class="Fn" id="bus_space_copy_region_4">bus_space_copy_region_4</code></a>(<var class="Fa">space</var>,
  <var class="Fa">srchandle</var>, <var class="Fa">srcoffset</var>,
  <var class="Fa">dsthandle</var>, <var class="Fa">dstoffset</var>,
  <var class="Fa">count</var>)</a></h2>
</section>
<section class="Ss">
<h2 class="Ss" id="bus_space_copy_region_8_space_srchandle_srcoffset_dsthandle_dstoffset_count"><a class="permalink" href="#bus_space_copy_region_8_space_srchandle_srcoffset_dsthandle_dstoffset_count"><a class="permalink" href="#bus_space_copy_region_8"><code class="Fn" id="bus_space_copy_region_8">bus_space_copy_region_8</code></a>(<var class="Fa">space</var>,
  <var class="Fa">srchandle</var>, <var class="Fa">srcoffset</var>,
  <var class="Fa">dsthandle</var>, <var class="Fa">dstoffset</var>,
  <var class="Fa">count</var>)</a></h2>
<p class="Pp">The <code class="Fn">bus_space_copy_region_N</code>() family of
    functions copies <var class="Fa">count</var> 1, 2, 4, or 8 byte data items
    in bus space from the area starting at byte offset
    <var class="Fa">srcoffset</var> in the region specified by
    <var class="Fa">srchandle</var> of the bus space specified by
    <var class="Fa">space</var> to the area starting at byte offset
    <var class="Fa">dstoffset</var> in the region specified by
    <var class="Fa">dsthandle</var> in the same bus space. Each successive data
    item read or written has an offset 1, 2, 4, or 8 bytes after the previous
    data item (depending on which function is used). All locations being read
    and written must lie within the bus space region specified by their
    respective handles.</p>
<p class="Pp">For portability, the starting addresses of the regions specified
    by the each handle plus its respective offset should be a multiple of the
    size of data items being copied. On some systems, not obeying this
    requirement may cause incorrect data to be copied, on others it may cause a
    system crash.</p>
<p class="Pp" id="bus_space_copy_region_N~2">Read and write operations done by
    the
    <a class="permalink" href="#bus_space_copy_region_N~2"><code class="Fn">bus_space_copy_region_N</code></a>()
    functions may be executed in any order. They may also be executed out of
    order with respect to other pending read and write operations unless order
    is enforced by use of the <code class="Fn">bus_space_barrier</code>()
    function. There is no way to insert barriers between reads or writes of
    individual bus space locations executed by the
    <code class="Fn">bus_space_copy_region_N</code>() functions.</p>
<p class="Pp" id="bus_space_copy_region_N~3">Overlapping copies between
    different subregions of a single region of bus space are handled correctly
    by the
    <a class="permalink" href="#bus_space_copy_region_N~3"><code class="Fn">bus_space_copy_region_N</code></a>()
    functions.</p>
<p class="Pp">These functions will never fail. If they would fail (e.g. because
    of an argument error), that indicates a software bug which should cause a
    panic. In that case, they will never return.</p>
</section>
<section class="Ss">
<h2 class="Ss" id="bus_space_set_region_1_space_handle_offset_value_count"><a class="permalink" href="#bus_space_set_region_1_space_handle_offset_value_count"><a class="permalink" href="#bus_space_set_region_1"><code class="Fn" id="bus_space_set_region_1">bus_space_set_region_1</code></a>(<var class="Fa">space</var>,
  <var class="Fa">handle</var>, <var class="Fa">offset</var>,
  <var class="Fa">value</var>, <var class="Fa">count</var>)</a></h2>
</section>
<section class="Ss">
<h2 class="Ss" id="bus_space_set_region_2_space_handle_offset_value_count"><a class="permalink" href="#bus_space_set_region_2_space_handle_offset_value_count"><a class="permalink" href="#bus_space_set_region_2"><code class="Fn" id="bus_space_set_region_2">bus_space_set_region_2</code></a>(<var class="Fa">space</var>,
  <var class="Fa">handle</var>, <var class="Fa">offset</var>,
  <var class="Fa">value</var>, <var class="Fa">count</var>)</a></h2>
</section>
<section class="Ss">
<h2 class="Ss" id="bus_space_set_region_4_space_handle_offset_value_count"><a class="permalink" href="#bus_space_set_region_4_space_handle_offset_value_count"><a class="permalink" href="#bus_space_set_region_4"><code class="Fn" id="bus_space_set_region_4">bus_space_set_region_4</code></a>(<var class="Fa">space</var>,
  <var class="Fa">handle</var>, <var class="Fa">offset</var>,
  <var class="Fa">value</var>, <var class="Fa">count</var>)</a></h2>
</section>
<section class="Ss">
<h2 class="Ss" id="bus_space_set_region_8_space_handle_offset_value_count"><a class="permalink" href="#bus_space_set_region_8_space_handle_offset_value_count"><a class="permalink" href="#bus_space_set_region_8"><code class="Fn" id="bus_space_set_region_8">bus_space_set_region_8</code></a>(<var class="Fa">space</var>,
  <var class="Fa">handle</var>, <var class="Fa">offset</var>,
  <var class="Fa">value</var>, <var class="Fa">count</var>)</a></h2>
<p class="Pp">The <code class="Fn">bus_space_set_region_N</code>() family of
    functions writes the given <var class="Fa">value</var> to
    <var class="Fa">count</var> 1, 2, 4, or 8 byte data items in bus space
    starting at byte offset <var class="Fa">offset</var> in the region specified
    by <var class="Fa">handle</var> of the bus space specified by
    <var class="Fa">space</var>. Each successive data item has an offset 1, 2,
    4, or 8 bytes after the previous data item (depending on which function is
    used). All locations being written must lie within the bus space region
    specified by <var class="Fa">handle</var>.</p>
<p class="Pp">For portability, the starting address of the region specified by
    <var class="Fa">handle</var> plus the offset should be a multiple of the
    size of data items being written. On some systems, not obeying this
    requirement may cause incorrect data to be written, on others it may cause a
    system crash.</p>
<p class="Pp" id="bus_space_set_region_N">Write operations done by the
    <a class="permalink" href="#bus_space_set_region_N"><code class="Fn">bus_space_set_region_N</code></a>()
    functions may be executed in any order. They may also be executed out of
    order with respect to other pending read and write operations unless order
    is enforced by use of the <code class="Fn">bus_space_barrier</code>()
    function. There is no way to insert barriers between writes of individual
    bus space locations executed by the
    <code class="Fn">bus_space_set_region_N</code>() functions.</p>
<p class="Pp">These functions will never fail. If they would fail (e.g. because
    of an argument error), that indicates a software bug which should cause a
    panic. In that case, they will never return.</p>
</section>
</section>
<section class="Sh">
<h1 class="Sh" id="READING_AND_WRITING_A_SINGLE_LOCATION_MULTIPLE_TIMES"><a class="permalink" href="#READING_AND_WRITING_A_SINGLE_LOCATION_MULTIPLE_TIMES">READING
  AND WRITING A SINGLE LOCATION MULTIPLE TIMES</a></h1>
<p class="Pp">Some devices implement single locations in bus space which are to
    be read or written multiple times to communicate data, e.g. some ethernet
    devices' packet buffer FIFOs. In order to allow drivers to manipulate these
    types of devices as efficiently as possible, the
    <a class="permalink" href="#bus_space_read_multi_N"><code class="Fn" id="bus_space_read_multi_N">bus_space_read_multi_N</code></a>(),
    <code class="Fn">bus_space_set_multi_N</code>(), and
    <code class="Fn">bus_space_write_multi_N</code>() families of functions are
    provided.</p>
<section class="Ss">
<h2 class="Ss" id="bus_space_read_multi_1_space_handle_offset_datap_count"><a class="permalink" href="#bus_space_read_multi_1_space_handle_offset_datap_count"><a class="permalink" href="#bus_space_read_multi_1"><code class="Fn" id="bus_space_read_multi_1">bus_space_read_multi_1</code></a>(<var class="Fa">space</var>,
  <var class="Fa">handle</var>, <var class="Fa">offset</var>,
  <var class="Fa">datap</var>, <var class="Fa">count</var>)</a></h2>
</section>
<section class="Ss">
<h2 class="Ss" id="bus_space_read_multi_2_space_handle_offset_datap_count"><a class="permalink" href="#bus_space_read_multi_2_space_handle_offset_datap_count"><a class="permalink" href="#bus_space_read_multi_2"><code class="Fn" id="bus_space_read_multi_2">bus_space_read_multi_2</code></a>(<var class="Fa">space</var>,
  <var class="Fa">handle</var>, <var class="Fa">offset</var>,
  <var class="Fa">datap</var>, <var class="Fa">count</var>)</a></h2>
</section>
<section class="Ss">
<h2 class="Ss" id="bus_space_read_multi_4_space_handle_offset_datap_count"><a class="permalink" href="#bus_space_read_multi_4_space_handle_offset_datap_count"><a class="permalink" href="#bus_space_read_multi_4"><code class="Fn" id="bus_space_read_multi_4">bus_space_read_multi_4</code></a>(<var class="Fa">space</var>,
  <var class="Fa">handle</var>, <var class="Fa">offset</var>,
  <var class="Fa">datap</var>, <var class="Fa">count</var>)</a></h2>
</section>
<section class="Ss">
<h2 class="Ss" id="bus_space_read_multi_8_space_handle_offset_datap_count"><a class="permalink" href="#bus_space_read_multi_8_space_handle_offset_datap_count"><a class="permalink" href="#bus_space_read_multi_8"><code class="Fn" id="bus_space_read_multi_8">bus_space_read_multi_8</code></a>(<var class="Fa">space</var>,
  <var class="Fa">handle</var>, <var class="Fa">offset</var>,
  <var class="Fa">datap</var>, <var class="Fa">count</var>)</a></h2>
<p class="Pp">The <code class="Fn">bus_space_read_multi_N</code>() family of
    functions reads <var class="Fa">count</var> 1, 2, 4, or 8 byte data items
    from bus space at byte offset <var class="Fa">offset</var> in the region
    specified by <var class="Fa">handle</var> of the bus space specified by
    <var class="Fa">space</var> and writes them into the array specified by
    <var class="Fa">datap</var>. Each successive data item is read from the same
    location in bus space. The location being read must lie within the bus space
    region specified by <var class="Fa">handle</var>.</p>
<p class="Pp">For portability, the starting address of the region specified by
    <var class="Fa">handle</var> plus the offset should be a multiple of the
    size of data items being read and the data array pointer should be properly
    aligned. On some systems, not obeying these requirements may cause incorrect
    data to be read, on others it may cause a system crash.</p>
<p class="Pp" id="bus_space_read_multi_N~2">Read operations done by the
    <a class="permalink" href="#bus_space_read_multi_N~2"><code class="Fn">bus_space_read_multi_N</code></a>()
    functions may be executed out of order with respect to other pending read
    and write operations unless order is enforced by use of the
    <code class="Fn">bus_space_barrier</code>() function. Because the
    <code class="Fn">bus_space_read_multi_N</code>() functions read the same bus
    space location multiple times, they place an implicit read barrier between
    each successive read of that bus space location.</p>
<p class="Pp">These functions will never fail. If they would fail (e.g. because
    of an argument error), that indicates a software bug which should cause a
    panic. In that case, they will never return.</p>
</section>
<section class="Ss">
<h2 class="Ss" id="bus_space_write_multi_1_space_handle_offset_datap_count"><a class="permalink" href="#bus_space_write_multi_1_space_handle_offset_datap_count"><a class="permalink" href="#bus_space_write_multi_1"><code class="Fn" id="bus_space_write_multi_1">bus_space_write_multi_1</code></a>(<var class="Fa">space</var>,
  <var class="Fa">handle</var>, <var class="Fa">offset</var>,
  <var class="Fa">datap</var>, <var class="Fa">count</var>)</a></h2>
</section>
<section class="Ss">
<h2 class="Ss" id="bus_space_write_multi_2_space_handle_offset_datap_count"><a class="permalink" href="#bus_space_write_multi_2_space_handle_offset_datap_count"><a class="permalink" href="#bus_space_write_multi_2"><code class="Fn" id="bus_space_write_multi_2">bus_space_write_multi_2</code></a>(<var class="Fa">space</var>,
  <var class="Fa">handle</var>, <var class="Fa">offset</var>,
  <var class="Fa">datap</var>, <var class="Fa">count</var>)</a></h2>
</section>
<section class="Ss">
<h2 class="Ss" id="bus_space_write_multi_4_space_handle_offset_datap_count"><a class="permalink" href="#bus_space_write_multi_4_space_handle_offset_datap_count"><a class="permalink" href="#bus_space_write_multi_4"><code class="Fn" id="bus_space_write_multi_4">bus_space_write_multi_4</code></a>(<var class="Fa">space</var>,
  <var class="Fa">handle</var>, <var class="Fa">offset</var>,
  <var class="Fa">datap</var>, <var class="Fa">count</var>)</a></h2>
</section>
<section class="Ss">
<h2 class="Ss" id="bus_space_write_multi_8_space_handle_offset_datap_count"><a class="permalink" href="#bus_space_write_multi_8_space_handle_offset_datap_count"><a class="permalink" href="#bus_space_write_multi_8"><code class="Fn" id="bus_space_write_multi_8">bus_space_write_multi_8</code></a>(<var class="Fa">space</var>,
  <var class="Fa">handle</var>, <var class="Fa">offset</var>,
  <var class="Fa">datap</var>, <var class="Fa">count</var>)</a></h2>
<p class="Pp">The <code class="Fn">bus_space_write_multi_N</code>() family of
    functions reads <var class="Fa">count</var> 1, 2, 4, or 8 byte data items
    from the array specified by <var class="Fa">datap</var> and writes them into
    bus space at byte offset <var class="Fa">offset</var> in the region
    specified by <var class="Fa">handle</var> of the bus space specified by
    <var class="Fa">space</var>. Each successive data item is written to the
    same location in bus space. The location being written must lie within the
    bus space region specified by <var class="Fa">handle</var>.</p>
<p class="Pp">For portability, the starting address of the region specified by
    <var class="Fa">handle</var> plus the offset should be a multiple of the
    size of data items being written and the data array pointer should be
    properly aligned. On some systems, not obeying these requirements may cause
    incorrect data to be written, on others it may cause a system crash.</p>
<p class="Pp" id="bus_space_write_multi_N">Write operations done by the
    <a class="permalink" href="#bus_space_write_multi_N"><code class="Fn">bus_space_write_multi_N</code></a>()
    functions may be executed out of order with respect to other pending read
    and write operations unless order is enforced by use of the
    <code class="Fn">bus_space_barrier</code>() function. Because the
    <code class="Fn">bus_space_write_multi_N</code>() functions write the same
    bus space location multiple times, they place an implicit write barrier
    between each successive write of that bus space location.</p>
<p class="Pp">These functions will never fail. If they would fail (e.g. because
    of an argument error), that indicates a software bug which should cause a
    panic. In that case, they will never return.</p>
</section>
<section class="Ss">
<h2 class="Ss" id="bus_space_set_multi_1_space_handle_offset_value_count"><a class="permalink" href="#bus_space_set_multi_1_space_handle_offset_value_count"><a class="permalink" href="#bus_space_set_multi_1"><code class="Fn" id="bus_space_set_multi_1">bus_space_set_multi_1</code></a>(<var class="Fa">space</var>,
  <var class="Fa">handle</var>, <var class="Fa">offset</var>,
  <var class="Fa">value</var>, <var class="Fa">count</var>)</a></h2>
</section>
<section class="Ss">
<h2 class="Ss" id="bus_space_set_multi_2_space_handle_offset_value_count"><a class="permalink" href="#bus_space_set_multi_2_space_handle_offset_value_count"><a class="permalink" href="#bus_space_set_multi_2"><code class="Fn" id="bus_space_set_multi_2">bus_space_set_multi_2</code></a>(<var class="Fa">space</var>,
  <var class="Fa">handle</var>, <var class="Fa">offset</var>,
  <var class="Fa">value</var>, <var class="Fa">count</var>)</a></h2>
</section>
<section class="Ss">
<h2 class="Ss" id="bus_space_set_multi_4_space_handle_offset_value_count"><a class="permalink" href="#bus_space_set_multi_4_space_handle_offset_value_count"><a class="permalink" href="#bus_space_set_multi_4"><code class="Fn" id="bus_space_set_multi_4">bus_space_set_multi_4</code></a>(<var class="Fa">space</var>,
  <var class="Fa">handle</var>, <var class="Fa">offset</var>,
  <var class="Fa">value</var>, <var class="Fa">count</var>)</a></h2>
</section>
<section class="Ss">
<h2 class="Ss" id="bus_space_set_multi_8_space_handle_offset_value_count"><a class="permalink" href="#bus_space_set_multi_8_space_handle_offset_value_count"><a class="permalink" href="#bus_space_set_multi_8"><code class="Fn" id="bus_space_set_multi_8">bus_space_set_multi_8</code></a>(<var class="Fa">space</var>,
  <var class="Fa">handle</var>, <var class="Fa">offset</var>,
  <var class="Fa">value</var>, <var class="Fa">count</var>)</a></h2>
<p class="Pp">The <code class="Fn">bus_space_set_multi_N</code>() writes
    <var class="Fa">value</var> into bus space at byte offset
    <var class="Fa">offset</var> in the region specified by
    <var class="Fa">handle</var> of the bus space specified by
    <var class="Fa">space</var>, <var class="Fa">count</var> times. The location
    being written must lie within the bus space region specified by
    <var class="Fa">handle</var>.</p>
<p class="Pp">For portability, the starting address of the region specified by
    <var class="Fa">handle</var> plus the offset should be a multiple of the
    size of data items being written and the data array pointer should be
    properly aligned. On some systems, not obeying these requirements may cause
    incorrect data to be written, on others it may cause a system crash.</p>
<p class="Pp" id="bus_space_set_multi_N">Write operations done by the
    <a class="permalink" href="#bus_space_set_multi_N"><code class="Fn">bus_space_set_multi_N</code></a>()
    functions may be executed out of order with respect to other pending read
    and write operations unless order is enforced by use of the
    <code class="Fn">bus_space_barrier</code>() function. Because the
    <code class="Fn">bus_space_set_multi_N</code>() functions write the same bus
    space location multiple times, they place an implicit write barrier between
    each successive write of that bus space location.</p>
<p class="Pp">These functions will never fail. If they would fail (e.g. because
    of an argument error), that indicates a software bug which should cause a
    panic. In that case, they will never return.</p>
</section>
</section>
<section class="Sh">
<h1 class="Sh" id="STREAM_FUNCTIONS"><a class="permalink" href="#STREAM_FUNCTIONS">STREAM
  FUNCTIONS</a></h1>
<p class="Pp">Most of the <code class="Nm">bus_space</code> functions imply a
    host byte-order and a bus byte-order and take care of any translation for
    the caller. In some cases, however, hardware may map a FIFO or some other
    memory region for which the caller may want to use multi-word, yet
    untranslated access. Access to these types of memory regions should be with
    the
    <a class="permalink" href="#bus_space_*_stream_N"><code class="Fn" id="bus_space_*_stream_N">bus_space_*_stream_N</code></a>()
    functions.</p>
<p class="Pp"></p>
<dl class="Bl-tag Bl-compact">
  <dt id="bus_space_read_stream_1"><a class="permalink" href="#bus_space_read_stream_1"><code class="Fn">bus_space_read_stream_1</code></a>()</dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="bus_space_read_stream_2"><a class="permalink" href="#bus_space_read_stream_2"><code class="Fn">bus_space_read_stream_2</code></a>()</dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="bus_space_read_stream_4"><a class="permalink" href="#bus_space_read_stream_4"><code class="Fn">bus_space_read_stream_4</code></a>()</dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="bus_space_read_stream_8"><a class="permalink" href="#bus_space_read_stream_8"><code class="Fn">bus_space_read_stream_8</code></a>()</dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="bus_space_read_multi_stream_1"><a class="permalink" href="#bus_space_read_multi_stream_1"><code class="Fn">bus_space_read_multi_stream_1</code></a>()</dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="bus_space_read_multi_stream_2"><a class="permalink" href="#bus_space_read_multi_stream_2"><code class="Fn">bus_space_read_multi_stream_2</code></a>()</dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="bus_space_read_multi_stream_4"><a class="permalink" href="#bus_space_read_multi_stream_4"><code class="Fn">bus_space_read_multi_stream_4</code></a>()</dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="bus_space_read_multi_stream_8"><a class="permalink" href="#bus_space_read_multi_stream_8"><code class="Fn">bus_space_read_multi_stream_8</code></a>()</dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="bus_space_read_region_stream_1"><a class="permalink" href="#bus_space_read_region_stream_1"><code class="Fn">bus_space_read_region_stream_1</code></a>()</dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="bus_space_read_region_stream_2"><a class="permalink" href="#bus_space_read_region_stream_2"><code class="Fn">bus_space_read_region_stream_2</code></a>()</dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="bus_space_read_region_stream_4"><a class="permalink" href="#bus_space_read_region_stream_4"><code class="Fn">bus_space_read_region_stream_4</code></a>()</dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="bus_space_read_region_stream_8"><a class="permalink" href="#bus_space_read_region_stream_8"><code class="Fn">bus_space_read_region_stream_8</code></a>()</dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="bus_space_write_stream_1"><a class="permalink" href="#bus_space_write_stream_1"><code class="Fn">bus_space_write_stream_1</code></a>()</dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="bus_space_write_stream_2"><a class="permalink" href="#bus_space_write_stream_2"><code class="Fn">bus_space_write_stream_2</code></a>()</dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="bus_space_write_stream_4"><a class="permalink" href="#bus_space_write_stream_4"><code class="Fn">bus_space_write_stream_4</code></a>()</dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="bus_space_write_stream_8"><a class="permalink" href="#bus_space_write_stream_8"><code class="Fn">bus_space_write_stream_8</code></a>()</dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="bus_space_write_multi_stream_1"><a class="permalink" href="#bus_space_write_multi_stream_1"><code class="Fn">bus_space_write_multi_stream_1</code></a>()</dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="bus_space_write_multi_stream_2"><a class="permalink" href="#bus_space_write_multi_stream_2"><code class="Fn">bus_space_write_multi_stream_2</code></a>()</dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="bus_space_write_multi_stream_4"><a class="permalink" href="#bus_space_write_multi_stream_4"><code class="Fn">bus_space_write_multi_stream_4</code></a>()</dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="bus_space_write_multi_stream_8"><a class="permalink" href="#bus_space_write_multi_stream_8"><code class="Fn">bus_space_write_multi_stream_8</code></a>()</dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="bus_space_write_region_stream_1"><a class="permalink" href="#bus_space_write_region_stream_1"><code class="Fn">bus_space_write_region_stream_1</code></a>()</dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="bus_space_write_region_stream_2"><a class="permalink" href="#bus_space_write_region_stream_2"><code class="Fn">bus_space_write_region_stream_2</code></a>()</dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="bus_space_write_region_stream_4"><a class="permalink" href="#bus_space_write_region_stream_4"><code class="Fn">bus_space_write_region_stream_4</code></a>()</dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="bus_space_write_region_stream_8"><a class="permalink" href="#bus_space_write_region_stream_8"><code class="Fn">bus_space_write_region_stream_8</code></a>()</dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="bus_space_copy_region_stream_1"><a class="permalink" href="#bus_space_copy_region_stream_1"><code class="Fn">bus_space_copy_region_stream_1</code></a>()</dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="bus_space_copy_region_stream_2"><a class="permalink" href="#bus_space_copy_region_stream_2"><code class="Fn">bus_space_copy_region_stream_2</code></a>()</dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="bus_space_copy_region_stream_4"><a class="permalink" href="#bus_space_copy_region_stream_4"><code class="Fn">bus_space_copy_region_stream_4</code></a>()</dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="bus_space_copy_region_stream_8"><a class="permalink" href="#bus_space_copy_region_stream_8"><code class="Fn">bus_space_copy_region_stream_8</code></a>()</dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="bus_space_set_multi_stream_1"><a class="permalink" href="#bus_space_set_multi_stream_1"><code class="Fn">bus_space_set_multi_stream_1</code></a>()</dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="bus_space_set_multi_stream_2"><a class="permalink" href="#bus_space_set_multi_stream_2"><code class="Fn">bus_space_set_multi_stream_2</code></a>()</dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="bus_space_set_multi_stream_4"><a class="permalink" href="#bus_space_set_multi_stream_4"><code class="Fn">bus_space_set_multi_stream_4</code></a>()</dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="bus_space_set_multi_stream_8"><a class="permalink" href="#bus_space_set_multi_stream_8"><code class="Fn">bus_space_set_multi_stream_8</code></a>()</dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="bus_space_set_region_stream_1"><a class="permalink" href="#bus_space_set_region_stream_1"><code class="Fn">bus_space_set_region_stream_1</code></a>()</dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="bus_space_set_region_stream_2"><a class="permalink" href="#bus_space_set_region_stream_2"><code class="Fn">bus_space_set_region_stream_2</code></a>()</dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="bus_space_set_region_stream_4"><a class="permalink" href="#bus_space_set_region_stream_4"><code class="Fn">bus_space_set_region_stream_4</code></a>()</dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="bus_space_set_region_stream_8"><a class="permalink" href="#bus_space_set_region_stream_8"><code class="Fn">bus_space_set_region_stream_8</code></a>()</dt>
  <dd style="width: auto;">&#x00A0;</dd>
</dl>
<p class="Pp">These functions are defined just as their non-stream counterparts,
    except that they provide no byte-order translation.</p>
</section>
<section class="Sh">
<h1 class="Sh" id="COMPATIBILITY"><a class="permalink" href="#COMPATIBILITY">COMPATIBILITY</a></h1>
<p class="Pp">The current <span class="Ux">NetBSD</span> version of the
    <code class="Nm">bus_space</code> interface specification differs slightly
    from the original specification that came into wide use and
    <span class="Ux">FreeBSD</span> adopted. A few of the function names and
    arguments have changed for consistency and increased functionality.</p>
</section>
<section class="Sh">
<h1 class="Sh" id="SEE_ALSO"><a class="permalink" href="#SEE_ALSO">SEE
  ALSO</a></h1>
<p class="Pp"><a class="Xr">bus_dma(9)</a></p>
</section>
<section class="Sh">
<h1 class="Sh" id="HISTORY"><a class="permalink" href="#HISTORY">HISTORY</a></h1>
<p class="Pp">The <code class="Nm">bus_space</code> functions were introduced in
    a different form (memory and I/O spaces were accessed via different sets of
    functions) in <span class="Ux">NetBSD 1.2</span>. The functions were merged
    to work on generic &#x201C;spaces&#x201D; early in the
    <span class="Ux">NetBSD 1.3</span> development cycle, and many drivers were
    converted to use them. This document was written later during the
    <span class="Ux">NetBSD 1.3</span> development cycle, and the specification
    was updated to fix some consistency problems and to add some missing
    functionality.</p>
<p class="Pp">The manual page was then adapted to the version of the interface
    that <span class="Ux">FreeBSD</span> imported for the CAM SCSI drivers, plus
    subsequent evolution. The <span class="Ux">FreeBSD</span>
    <code class="Nm">bus_space</code> version was imported in
    <span class="Ux">FreeBSD 3.0</span>.</p>
</section>
<section class="Sh">
<h1 class="Sh" id="AUTHORS"><a class="permalink" href="#AUTHORS">AUTHORS</a></h1>
<p class="Pp">The <code class="Nm">bus_space</code> interfaces were designed and
    implemented by the <span class="Ux">NetBSD</span> developer community.
    Primary contributors and implementors were <span class="An">Chris
    Demetriou</span>, <span class="An">Jason Thorpe</span>, and
    <span class="An">Charles Hannum</span>, but the rest of the
    <span class="Ux">NetBSD</span> developers and the user community played a
    significant role in development.</p>
<p class="Pp"><span class="An">Justin Gibbs</span> ported these interfaces to
    <span class="Ux">FreeBSD</span>.</p>
<p class="Pp"><span class="An">Chris Demetriou</span> wrote this manual
  page.</p>
<p class="Pp"><span class="An">Warner Losh</span> modified it for the
    <span class="Ux">FreeBSD</span> implementation.</p>
</section>
<section class="Sh">
<h1 class="Sh" id="BUGS"><a class="permalink" href="#BUGS">BUGS</a></h1>
<p class="Pp">This manual may not completely and accurately document the
    interface, and many parts of the interface are unspecified.</p>
</section>
</div>
<table class="foot">
  <tr>
    <td class="foot-date">May 1, 2021</td>
    <td class="foot-os">FreeBSD 15.0</td>
  </tr>
</table>