sample_gpio_driver.html

ADI 公司blackfin系列的用户使用文挡。

<span class="br0">&#125;</span>
&nbsp;</pre>
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<!-- SECTION [2850-3645] -->
<h3><a name="write_function" id="write_function">Write Function</a></h3>
<div class="level3">

<p>
 The write function allows the user code to set or clear the output leds
</p>
<pre class="code c">&nbsp;
<span class="kw4">static</span> ssize_t
pflags_write <span class="br0">&#40;</span><span class="kw4">struct</span> file *filp, <span class="kw4">const</span> <span class="kw4">char</span> *buf, size_t size, loff_t * offp<span class="br0">&#41;</span>
<span class="br0">&#123;</span>
&nbsp;
  <span class="kw4">int</span> minor = check_minor <span class="br0">&#40;</span>filp-&gt;f_dentry-&gt;d_inode<span class="br0">&#41;</span>;
&nbsp;
  <span class="kw4">volatile</span> <span class="kw4">unsigned</span> <span class="kw4">short</span> *set_or_clear;
&nbsp;
  DPRINTK <span class="br0">&#40;</span><span class="st0">"pfbits driver for bf53x minor = %d<span class="es0">\n</span>"</span>, minor<span class="br0">&#41;</span>;
&nbsp;
  <span class="kw1">if</span> <span class="br0">&#40;</span>minor &lt; <span class="nu0">0</span><span class="br0">&#41;</span>
    <span class="kw1">return</span> -ENODEV;
&nbsp;
  <span class="kw1">if</span> <span class="br0">&#40;</span>size &lt; <span class="nu0">2</span><span class="br0">&#41;</span>
    <span class="kw1">return</span> -EMSGSIZE;
&nbsp;
  <span class="kw1">if</span> <span class="br0">&#40;</span>!buf<span class="br0">&#41;</span>
    <span class="kw1">return</span> -EFAULT;
&nbsp;
  <span class="co1">// clear if '0' set if '1'</span>
  set_or_clear =
   <span class="br0">&#40;</span>buf<span class="br0">&#91;</span><span class="nu0">0</span><span class="br0">&#93;</span> == <span class="st0">'0'</span><span class="br0">&#41;</span> ? 
       <span class="br0">&#40;</span><span class="br0">&#40;</span><span class="kw4">volatile</span> <span class="kw4">unsigned</span> <span class="kw4">short</span> *<span class="br0">&#41;</span> FIO_FLAG_C<span class="br0">&#41;</span> : 
       <span class="br0">&#40;</span><span class="br0">&#40;</span><span class="kw4">volatile</span> <span class="kw4">unsigned</span> <span class="kw4">short</span> *<span class="br0">&#41;</span> FIO_FLAG_S<span class="br0">&#41;</span>;
&nbsp;
  *set_or_clear = <span class="br0">&#40;</span><span class="nu0">1</span> &lt;&lt; minor<span class="br0">&#41;</span>;
&nbsp;
  <span class="kw1">return</span> size;
&nbsp;
<span class="br0">&#125;</span>
&nbsp;</pre>
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<!-- SECTION [3646-4347] -->
<h3><a name="interrupt_handler" id="interrupt_handler">Interrupt Handler</a></h3>
<div class="level3">

<p>
 This will clear the interrupt and input the flags state and detect a change.
</p>

<p>
(Note It should possibly only mask the pins of interest )
</p>

<p>
The interrupt handler will wake up the <strong>pflags_in_waitq</strong> wait queue.
</p>
<pre class="code c">&nbsp;
<span class="kw4">static</span> irqreturn_t pflags_irq_handler <span class="br0">&#40;</span> <span class="kw4">int</span> irq, <span class="kw4">void</span> *dev_id, <span class="kw4">struct</span> pt_regs *regs <span class="br0">&#41;</span><span class="br0">&#123;</span>
&nbsp;
  <span class="kw4">short</span> pflags_nextstate = *pFIO_FLAG_D;
&nbsp;
  <span class="coMULTI">/* FIXME: Clear only status of flag pin that caused the interrupt */</span>
  *pFIO_FLAG_C = 0xFFFF; <span class="coMULTI">/* clear irq status on interrupt lines */</span>
&nbsp;
  printk<span class="br0">&#40;</span><span class="st0">"pflags_irq_handler <span class="es0">\n</span>"</span><span class="br0">&#41;</span>;
&nbsp;
  pflags_statechanged   = pflags_laststate ^ pflags_nextstate;
  pflags_laststate      = pflags_nextstate;
&nbsp;
  wake_up<span class="br0">&#40;</span> &amp;pflags_in_waitq <span class="br0">&#41;</span>;
&nbsp;
  <span class="kw1">return</span> IRQ_HANDLED;
&nbsp;
<span class="br0">&#125;</span>
&nbsp;</pre>
</div>
<!-- SECTION [4348-5076] -->
<h3><a name="poll_function" id="poll_function">Poll Function</a></h3>
<div class="level3">

<p>
 The Poll function is optional. It will indicate that the state of the input pins has changed.
</p>
<pre class="code c"><span class="kw4">static</span> <span class="kw4">unsigned</span> <span class="kw4">int</span> pflags_poll<span class="br0">&#40;</span><span class="kw4">struct</span> file *filp, <span class="kw4">struct</span> poll_table_struct *wait<span class="br0">&#41;</span><span class="br0">&#123;</span>
&nbsp;
  <span class="kw4">int</span> minor = check_minor<span class="br0">&#40;</span> filp-&gt;f_dentry-&gt;d_inode <span class="br0">&#41;</span>;
  <span class="kw4">int</span> changed=<span class="nu0">0</span>;
  <span class="kw4">unsigned</span> <span class="kw4">int</span> mask = <span class="nu0">0</span>;
&nbsp;
  <span class="kw1">if</span><span class="br0">&#40;</span> minor &lt; <span class="nu0">0</span> <span class="br0">&#41;</span> <span class="kw1">return</span> -ENODEV;
&nbsp;
<span class="co1">//    *pFIO_MASKA_C |= (1 &lt;&lt; minor);</span>
  *pFIO_MASKA_S |= <span class="br0">&#40;</span><span class="nu0">1</span> &lt;&lt; minor<span class="br0">&#41;</span>;
  *pFIO_INEN    |= <span class="br0">&#40;</span><span class="nu0">1</span> &lt;&lt; minor<span class="br0">&#41;</span>;
&nbsp;
  <span class="kw1">if</span> <span class="br0">&#40;</span>filp-&gt;f_mode &amp; FMODE_READ<span class="br0">&#41;</span><span class="br0">&#123;</span>
      <span class="coMULTI">/* attention! this wakes up when /any/ of the flags changes */</span>
      poll_wait<span class="br0">&#40;</span>filp, &amp;pflags_in_waitq, wait<span class="br0">&#41;</span>;
&nbsp;
      changed = pflags_statechanged &amp; <span class="br0">&#40;</span><span class="nu0">1</span>&lt;&lt;minor<span class="br0">&#41;</span>;
      <span class="kw1">if</span> <span class="br0">&#40;</span> changed <span class="br0">&#41;</span> mask |= POLLIN | POLLRDNORM;
  <span class="br0">&#125;</span>
&nbsp;
  <span class="coMULTI">/* we can always write */</span>
  <span class="kw1">if</span> <span class="br0">&#40;</span>filp-&gt;f_mode &amp; FMODE_WRITE<span class="br0">&#41;</span>
      mask |= POLLOUT | POLLWRNORM;
&nbsp;
  <span class="kw1">return</span> mask;
<span class="br0">&#125;</span>
&nbsp;</pre>
</div>
<!-- SECTION [5077-5909] -->
<h3><a name="exit_function" id="exit_function">Exit Function</a></h3>
<div class="level3">

<p>
A simple exit function removes the proc interface 
</p>
<pre class="code"> (NOTE the Poll Irq is not removed !! )</pre>
<pre class="code c"><span class="kw4">void</span> __exit
blackfin_plags_exit <span class="br0">&#40;</span><span class="kw4">void</span><span class="br0">&#41;</span>
<span class="br0">&#123;</span>
&nbsp;
  remove_proc_entry <span class="br0">&#40;</span><span class="st0">"driver/pflags"</span>, <span class="kw2">NULL</span><span class="br0">&#41;</span>;
&nbsp;
<span class="br0">&#125;</span>
&nbsp;
module_exit <span class="br0">&#40;</span>blackfin_plags_exit<span class="br0">&#41;</span>;
&nbsp;</pre>
</div>
<!-- SECTION [5910-6172] -->
<h3><a name="ioctl_code" id="ioctl_code">IOCTL Code</a></h3>
<div class="level3">
<pre class="code c"><span class="kw4">static</span> <span class="kw4">int</span>
pflags_ioctl <span class="br0">&#40;</span><span class="kw4">struct</span> inode *inode, <span class="kw4">struct</span> file *filp, uint cmd,
              <span class="kw4">unsigned</span> <span class="kw4">long</span> arg<span class="br0">&#41;</span>
<span class="br0">&#123;</span>
&nbsp;
    <span class="kw4">int</span> minor = check_minor <span class="br0">&#40;</span>filp-&gt;f_dentry-&gt;d_inode<span class="br0">&#41;</span>;
&nbsp;
&nbsp;
    <span class="kw1">if</span> <span class="br0">&#40;</span>minor &lt; <span class="nu0">0</span><span class="br0">&#41;</span>
        <span class="kw1">return</span> -ENODEV;
&nbsp;
    DPRINTK <span class="br0">&#40;</span><span class="st0">"pfbits driver for bf53x minor = %d<span class="es0">\n</span>"</span>, minor<span class="br0">&#41;</span>;
&nbsp;
    <span class="kw1">switch</span> <span class="br0">&#40;</span>cmd<span class="br0">&#41;</span> <span class="br0">&#123;</span>
        <span class="kw1">case</span> SET_FIO_DIR:
            DPRINTK <span class="br0">&#40;</span><span class="st0">"pflags_ioctl: SET_FIO_DIR <span class="es0">\n</span>"</span><span class="br0">&#41;</span>;
            <span class="kw1">if</span> <span class="br0">&#40;</span>arg<span class="br0">&#41;</span> <span class="br0">&#123;</span>                <span class="co1">// OUTPUT</span>
                *pFIO_DIR |= <span class="br0">&#40;</span><span class="nu0">1</span> &lt;&lt; minor<span class="br0">&#41;</span>;
            <span class="br0">&#125;</span> <span class="kw1">else</span> <span class="br0">&#123;</span>                   <span class="co1">// INPUT</span>
                *pFIO_DIR &amp;= ~<span class="br0">&#40;</span><span class="nu0">1</span> &lt;&lt; minor<span class="br0">&#41;</span>;
            <span class="br0">&#125;</span>
            <span class="kw2">break</span>;
&nbsp;
        <span class="kw1">case</span> SET_FIO_POLAR:
            DPRINTK <span class="br0">&#40;</span><span class="st0">"pflags_ioctl: SET_FIO_POLAR <span class="es0">\n</span>"</span>, arg<span class="br0">&#41;</span>;
            <span class="kw1">if</span> <span class="br0">&#40;</span>arg<span class="br0">&#41;</span> <span class="br0">&#123;</span>                <span class="co1">// ACTIVELOW_FALLINGEDGE</span>
                *pFIO_POLAR |= <span class="br0">&#40;</span><span class="nu0">1</span> &lt;&lt; minor<span class="br0">&#41;</span>;
            <span class="br0">&#125;</span>  <span class="kw1">else</span> <span class="br0">&#123;</span>            <span class="co1">// ACTIVEHIGH_RISINGEDGE</span>
                     *pFIO_POLAR &amp;= ~<span class="br0">&#40;</span><span class="nu0">1</span> &lt;&lt; minor<span class="br0">&#41;</span>;
            <span class="br0">&#125;</span>
            <span class="kw2">break</span>;
&nbsp;
       <span class="kw1">case</span> SET_FIO_EDGE:
            DPRINTK <span class="br0">&#40;</span><span class="st0">"pflags_ioctl: SET_FIO_EDGE <span class="es0">\n</span>"</span><span class="br0">&#41;</span>;
&nbsp;
           <span class="kw1">if</span> <span class="br0">&#40;</span>arg<span class="br0">&#41;</span> <span class="br0">&#123;</span>                <span class="co1">// EDGE</span>
               *pFIO_EDGE |= <span class="br0">&#40;</span><span class="nu0">1</span> &lt;&lt; minor<span class="br0">&#41;</span>;
            <span class="br0">&#125;</span> <span class="kw1">else</span>  <span class="br0">&#123;</span>                   <span class="co1">// LEVEL</span>
               *pFIO_EDGE &amp;= ~<span class="br0">&#40;</span><span class="nu0">1</span> &lt;&lt; minor<span class="br0">&#41;</span>;
            <span class="br0">&#125;</span>
            <span class="kw2">break</span>;
&nbsp;
       <span class="kw1">case</span> SET_FIO_BOTH:
           DPRINTK <span class="br0">&#40;</span><span class="st0">"pflags_ioctl: SET_FIO_BOTH <span class="es0">\n</span>"</span><span class="br0">&#41;</span>;
&nbsp;
           <span class="kw1">if</span> <span class="br0">&#40;</span>arg<span class="br0">&#41;</span> <span class="br0">&#123;</span>                <span class="co1">// BOTHEDGES</span>
              *pFIO_BOTH |= <span class="br0">&#40;</span><span class="nu0">1</span> &lt;&lt; minor<span class="br0">&#41;</span>;
          <span class="br0">&#125;</span> <span class="kw1">else</span> <span class="br0">&#123;</span>                   <span class="co1">// SINGLEEDGE</span>
              *pFIO_BOTH &amp;= ~<span class="br0">&#40;</span><span class="nu0">1</span> &lt;&lt; minor<span class="br0">&#41;</span>;
          <span class="br0">&#125;</span>
          <span class="kw2">break</span>;
 
       <span class="kw1">case</span> SET_FIO_INEN:
           DPRINTK <span class="br0">&#40;</span><span class="st0">"pflags_ioctl: SET_FIO_INEN <span class="es0">\n</span>"</span><span class="br0">&#41;</span>;
           <span class="kw1">if</span> <span class="br0">&#40;</span>arg<span class="br0">&#41;</span> <span class="br0">&#123;</span>                <span class="co1">// OUTPUT_ENABLE</span>
              *pFIO_INEN |= <span class="br0">&#40;</span><span class="nu0">1</span> &lt;&lt; minor<span class="br0">&#41;</span>;
           <span class="br0">&#125;</span> <span class="kw1">else</span> <span class="br0">&#123;</span>                   <span class="co1">// INPUT_DISABLE</span>
              *pFIO_INEN &amp;= ~<span class="br0">&#40;</span><span class="nu0">1</span> &lt;&lt; minor<span class="br0">&#41;</span>;
           <span class="br0">&#125;</span>
           <span class="kw2">break</span>;
&nbsp;
       <span class="kw1">default</span>:
           <span class="kw1">return</span> -EINVAL;
    <span class="br0">&#125;</span>  <span class="co1">// end switch</span>
    <span class="kw1">return</span> <span class="nu0">0</span>;
<span class="br0">&#125;</span>
&nbsp;</pre>
</div>
<!-- SECTION [6173-8124] -->
<h3><a name="proc_interface" id="proc_interface">Proc Interface</a></h3>
<div class="level3">

<p>
 This driver has an example proc interface This uses a small function to populate a string buffer (<strong>page</strong>)  with data to be returned to the user.
</p>

<p>
This code has some additional complexity in that is handles part of the multi  page capibility of the proc interface.
</p>

<p>
In this case this ios not needed. A simpler 
</p>
<pre class="code c">&nbsp;
<span class="co1">// from the source example </span>
<span class="kw4">static</span> <span class="kw4">int</span>
pflags_read_proc <span class="br0">&#40;</span><span class="kw4">char</span> *page, <span class="kw4">char</span> **start, off_t off,
                  <span class="kw4">int</span> count, <span class="kw4">int</span> *eof, <span class="kw4">void</span> *data<span class="br0">&#41;</span>
<span class="br0">&#123;</span>
  <span class="kw4">int</span> len = <span class="nu0">0</span>;