字符设备之LED-定时器（timer）

led_timer.c

#include #include #include #include #include #include #include #include #include #include static volatile unsigned long * gpfcon; // = (volatile unsigned long *)0x56000050; static volatile unsigned long * gpfdat; // = (volatile unsigned long *)0x56000054; static struct timer_list led_timer; void led_timer_function(unsigned long data) {  static int cur_val = 0;    if (cur_val)  {   cur_val = 0;   *gpfdat &= ~(1<<4);  }  else  {   cur_val = 1;   *gpfdat |= (1<<4);  }  mod_timer(&led_timer, jiffies+50); /* 50* 10ms = 500ms = 0.5s */ } int led_timer_init(void) {  gpfcon = ioremap(0x56000050, 8); /* 得到虚拟地址 */  gpfdat = gpfcon + 1;  *gpfcon &= ~(0x3 << (4*2));  *gpfcon |= (0x1 << (4*2));;  init_timer(&led_timer);  led_timer.function = led_timer_function;  led_timer.expires = jiffies+50;  add_timer(&led_timer); } void led_timer_exit(void) {  del_timer(&led_timer);  iounmap(gpfcon); } module_init(led_timer_init); module_exit(led_timer_exit); MODULE_LICENSE("GPL");