example42.c

Linux Kernel Programming by Examples(1)[Xeroo]

/** @file example4.c
 *
 * \brief second example of input subsystem driver
 *
 * See Linux Journal Feb. 2003
 *
 * Requires
 *   insmod input
 *  
 * This module generate LED "Num Lock" events
 * which are passed to the handlers. To see them we need an 
 * handler ...
 */

#include <linux/input.h>   /* input_dev */
#include <linux/module.h>
/* #include <linux/modversions.h> */
#include <linux/init.h>

/* MODULE_LICENSE( "GPL" );  */

struct input_dev example4_dev;

void example4_timeout( unsigned long unused /* UNUSED */ )
{ 
  static int x = 0;

  x ++;
  if ( x == 4 ) {
    x = 0;
  }
  /* 
  printk( KERN_ALERT "Example4 event value %d handle %p open %d\n", 
    x, example4_dev.handle, example4_dev.handle->open );
  */
  input_event( &example4_dev, EV_LED, LED_NUML, x );
  /* input_sync( &example4_dev ); */

  mod_timer( &example4_dev.timer, jiffies + 10*HZ );
}

static int __init example4_init( void )
{
  /* extra safe initialization */
  memset( &example4_dev, 0, sizeof(struct input_dev) );
#if 0
  init_input_dev( &example4_dev );
#endif


  /* set up descriptive labels */
  example4_dev.name = "Example 4 device";
#if 0
  example4_dev.phys = "A/Fake/Path";
  example4_dev.id.bustype = BUS_HOST;
  example4_dev.id.vendor  = 0x0001;
  example4_dev.id.product = 0x0004;  // our fourth product
  exampleple4v.id.version = 0x0101;  // version 1.1
#else
  example4_dev.idbus     = BUS_ISA;
  example4_dev.idvendor  = 0x0001;
  example4_dev.idproduct = 0x0004;  // our fourth product
  example4_dev.idversion = 0x0101;  // version 1.1
#endif
  
  set_bit( EV_LED, example4_dev.evbit );
  set_bit( LED_NUML, example4_dev.ledbit );
  set_bit( LED_CAPSL, example4_dev.ledbit );
  set_bit( LED_SCROLLL, example4_dev.ledbit );

  input_register_device( &example4_dev );

  init_timer( &example4_dev.timer );
  example4_dev.timer.function = example4_timeout;
  example4_dev.timer.expires  = jiffies + HZ;
  add_timer( &example4_dev.timer );

  return 0;
}

static void __exit example4_exit( void )
{
  del_timer_sync( &example4_dev.timer );
  input_unregister_device( &example4_dev );
}

module_init( example4_init );
module_exit( example4_exit );