Linux在应用层读写寄存器的方法及实现实例
<p><strong>Linux在应用层读写寄存器的方法</strong></p>
<p>
可以通过操作/dev/mem设备文件，以及mmap函数，将寄存器的地址映射到用户空间，直接在应用层对寄存器进行操作，示例如下：</p>
<div class="jb51code">
<div>
<div class="syntaxhighlightercpp" id="highlighter_271608">
<div class="toolbar">
<span>?</span>
</div>
<table border="0" cellpadding="0" cellspacing="0"><tbody><tr>
<td class="gutter">
<div class="line number1 index0 alt2">
1</div>
<div class="line number2 index1 alt1">
2</div>
<div class="line number3 index2 alt2">
3</div>
<div class="line number4 index3 alt1">
4</div>
<div class="line number5 index4 alt2">
5</div>
<div class="line number6 index5 alt1">
6</div>
<div class="line number7 index6 alt2">
7</div>
<div class="line number8 index7 alt1">
8</div>
<div class="line number9 index8 alt2">
9</div>
<div class="line number10 index9 alt1">
10</div>
<div class="line number11 index10 alt2">
11</div>
<div class="line number12 index11 alt1">
12</div>
<div class="line number13 index12 alt2">
13</div>
<div class="line number14 index13 alt1">
14</div>
<div class="line number15 index14 alt2">
15</div>
<div class="line number16 index15 alt1">
16</div>
<div class="line number17 index16 alt2">
17</div>
<div class="line number18 index17 alt1">
18</div>
<div class="line number19 index18 alt2">
19</div>
<div class="line number20 index19 alt1">
20</div>
<div class="line number21 index20 alt2">
21</div>
<div class="line number22 index21 alt1">
22</div>
<div class="line number23 index22 alt2">
23</div>
<div class="line number24 index23 alt1">
24</div>
<div class="line number25 index24 alt2">
25</div>
<div class="line number26 index25 alt1">
26</div>
<div class="line number27 index26 alt2">
27</div>
<div class="line number28 index27 alt1">
28</div>
<div class="line number29 index28 alt2">
29</div>
<div class="line number30 index29 alt1">
30</div>
<div class="line number31 index30 alt2">
31</div>
<div class="line number32 index31 alt1">
32</div>
<div class="line number33 index32 alt2">
33</div>
<div class="line number34 index33 alt1">
34</div>
<div class="line number35 index34 alt2">
35</div>
<div class="line number36 index35 alt1">
36</div>
<div class="line number37 index36 alt2">
37</div>
<div class="line number38 index37 alt1">
38</div>
<div class="line number39 index38 alt2">
39</div>
<div class="line number40 index39 alt1">
40</div>
<div class="line number41 index40 alt2">
41</div>
<div class="line number42 index41 alt1">
42</div>
<div class="line number43 index42 alt2">
43</div>
<div class="line number44 index43 alt1">
44</div>
</td>
<td class="code">
<div class="container">
<div class="line number1 index0 alt2">
<code class="cpp preprocessor">#include <stdio.h> </code>
</div>
<div class="line number2 index1 alt1">
<code class="cpp preprocessor">#include <stdlib.h> </code>
</div>
<div class="line number3 index2 alt2">
<code class="cpp preprocessor">#include <time.h> </code>
</div>
<div class="line number4 index3 alt1">
<code class="cpp preprocessor">#include <unistd.h> </code>
</div>
<div class="line number5 index4 alt2">
<code class="cpp preprocessor">#include <fcntl.h> </code>
</div>
<div class="line number6 index5 alt1">
<code class="cpp preprocessor">#include <unistd.h> </code>
</div>
<div class="line number7 index6 alt2">
<code class="cpp preprocessor">#include <sys/mman.h> </code>
</div>
<div class="line number8 index7 alt1">
<code class="cpp preprocessor">#define AUDIO_REG_BASE (0xB800E000) </code>
</div>
<div class="line number9 index8 alt2">
<code class="cpp preprocessor">#define MAP_SIZE 0xFF </code>
</div>
<div class="line number10 index9 alt1">
<code class="cpp spaces"> </code>
</div>
<div class="line number11 index10 alt2">
<code class="cpp keyword bold">static</code> <code class="cpp color1 bold">int</code> <code class="cpp plain">dev_fd; </code>
</div>
<div class="line number12 index11 alt1">
<code class="cpp color1 bold">int</code> <code class="cpp plain">main(</code><code class="cpp color1 bold">int</code> <code class="cpp plain">argc, </code><code class="cpp color1 bold">char</code> <code class="cpp plain">**argv) </code>
</div>
<div class="line number13 index12 alt2">
<code class="cpp plain">{ </code>
</div>
<div class="line number14 index13 alt1">
<code class="cpp spaces"> </code>
</div>
<div class="line number15 index14 alt2">
<code class="cpp spaces"> </code><code class="cpp plain">dev_fd = open(</code><code class="cpp string">"/dev/mem"</code><code class="cpp plain">, O_RDWR | O_NDELAY); </code>
</div>
<div class="line number16 index15 alt1">
<code class="cpp spaces"> </code>
</div>
<div class="line number17 index16 alt2">
<code class="cpp spaces"> </code><code class="cpp keyword bold">if</code> <code class="cpp plain">(dev_fd < 0) </code>
</div>
<div class="line number18 index17 alt1">
<code class="cpp spaces"> </code><code class="cpp plain">{ </code>
</div>
<div class="line number19 index18 alt2">
<code class="cpp spaces"> </code><code class="cpp functions bold">printf</code><code class="cpp plain">(</code><code class="cpp string">"open(/dev/mem) failed."</code><code class="cpp plain">); </code>
</div>
<div class="line number20 index19 alt1">
<code class="cpp spaces"> </code><code class="cpp keyword bold">return</code> <code class="cpp plain">0; </code>
</div>
<div class="line number21 index20 alt2">
<code class="cpp spaces"> </code><code class="cpp plain">} </code>
</div>
<div class="line number22 index21 alt1">
<code class="cpp spaces"> </code>
</div>
<div class="line number23 index22 alt2">
<code class="cpp spaces"> </code><code class="cpp plain">unsigned </code><code class="cpp color1 bold">char</code> <code class="cpp plain">*map_base=(unsigned </code><code class="cpp color1 bold">char</code> <code class="cpp plain">* )mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, dev_fd, AUDIO_REG_BASE ); </code>
</div>
<div class="line number24 index23 alt1">
<code class="cpp spaces"> </code>
</div>
<div class="line number25 index24 alt2">
<code class="cpp spaces"> </code><code class="cpp functions bold">printf</code><code class="cpp plain">(</code><code class="cpp string">"%x \n"</code><code class="cpp plain">, *(</code><code class="cpp keyword bold">volatile</code> <code class="cpp plain">unsigned </code><code class="cpp color1 bold">int</code> <code class="cpp plain">*)(map_base+0x38)); </code><code class="cpp comments">//打印该寄存器地址的value </code>
</div>
<div class="line number26 index25 alt1">
<code class="cpp spaces"> </code>
</div>
<div class="line number27 index26 alt2">
<code class="cpp preprocessor">#if 1 // LINE IN </code>
</div>
<div class="line number28 index27 alt1">
<code class="cpp spaces"> </code><code class="cpp functions bold">printf</code><code class="cpp plain">(</code><code class="cpp string">"%x \n"</code><code class="cpp plain">, *(</code><code class="cpp keyword bold">volatile</code> <code class="cpp plain">unsigned </code><code class="cpp color1 bold">int</code> <code class="cpp plain">*)(map_base+0x30)); </code>
</div>
<div class="line number29 index28 alt2">
<code class="cpp spaces"> </code>
</div>
<div class="line number30 index29 alt1">
<code class="cpp spaces"> </code><code class="cpp plain">*(</code><code class="cpp keyword bold">volatile</code> <code class="cpp plain">unsigned </code><code class="cpp color1 bold">int</code> <code class="cpp plain">*)(map_base + 0x30) = 0x208121bc; </code><code class="cpp comments">//修改该寄存器地址的value </code>
</div>
<div class="line number31 index30 alt2">
<code class="cpp spaces"> </code><code class="cpp plain">usleep(1000000); </code>
</div>
<div class="line number32 index31 alt1">
<code class="cpp spaces"> </code><code class="cpp plain">*(</code><code class="cpp keyword bold">volatile</code> <code class="cpp plain">unsigned </code><code class="cpp color1 bold">int</code> <code class="cpp plain">*)(map_base + 0x30) &= ~(0x1<<16); </code><code class="cpp comments">//修改该寄存器地址的value </code>
</div>
<div class="line number33 index32 alt2">
<code class="cpp spaces"> </code><code class="cpp plain">usleep(1000000); </code>
</div>
<div class="line number34 index33 alt1">
<code class="cpp spaces"> </code>
</div>
<div class="line number35 index34 alt2">
<code class="cpp spaces"> </code><code class="cpp functions bold">printf</code><code class="cpp plain">(</code><code class="cpp string">"%x \n"</code><code class="cpp plain">, *(</code><code class="cpp keyword bold">volatile</code> <code class="cpp plain">unsigned </code><code class="cpp color1 bold">int</code> <code class="cpp plain">*)(map_base+0x30)); </code>
</div>
<div class="line number36 index35 alt1">
<code class="cpp preprocessor">#endif </code>
</div>
<div class="line number37 index36 alt2">
<code class="cpp spaces"> </code>
</div>
<div class="line number38 index37 alt1">
<code class="cpp spaces"> </code><code class="cpp keyword bold">if</code><code class="cpp plain">(dev_fd) </code>
</div>
<div class="line number39 index38 alt2">
<code class="cpp spaces"> </code><code class="cpp plain">close(dev_fd); </code>
</div>
<div class="line number40 index39 alt1">
<code class="cpp spaces"> </code>
</div>
<div class="line number41 index40 alt2">
<code class="cpp spaces"> </code><code class="cpp plain">munmap(map_base,MAP_SIZE);</code><code class="cpp comments">//解除映射关系 </code>
</div>
<div class="line number42 index41 alt1">
<code class="cpp spaces"> </code>
</div>
<div class="line number43 index42 alt2">
<code class="cpp spaces"> </code><code class="cpp keyword bold">return</code> <code class="cpp plain">0; </code>
</div>
<div class="line number44 index43 alt1">
<code class="cpp plain">} </code>
</div>
</div>
</td>
</tr></tbody></table>
</div>
</div>
<div class="codetool" id="codetool">
<div class="code_n">
<textarea></textarea>
</div>
</div>
</div>
<p>
感谢阅读，希望能帮助到大家，谢谢大家对本站的支持！</p>
頁:
[1]