/*timer handle*/
static void change_status(unsigned long time)
{
printk(KERN_INFO "---------handle---------------\nWangyf: Enter timer handle!\n");
printk(KERN_INFO "Wangyf: gpio_get_value = %d\n",gpio_get_value(GPIO_NUM));
if(gpio_get_value(GPIO_NUM) == 1) {
printk(KERN_INFO "Wangyf: led down!\n");
gpio_set_value(GPIO_NUM,0);
}
else if(gpio_get_value(GPIO_NUM) == 0) {
printk(KERN_INFO "Wangyf: led up!\n");
gpio_set_value(GPIO_NUM,1);
}
if(blink_flag){
printk(KERN_INFO "Wangyf: Add timer again!\n----------------------------\n");
my_timer.expires = jiffies + HZ;
add_timer(&my_timer);
}
return;
}
/*set blink*/
static ssize_t blink_gpio(struct device *dev,
struct device_attribute *attr,
char *buf,size_t size)
{
int blink_status;
printk(KERN_INFO "Wangyf: blink get order from echo!\n");
sscanf(buf,"%du",&blink_status);
printk(KERN_INFO "Wangyf: blink_status = %d\n",blink_status);
if(blink_status){
printk(KERN_INFO "Wangyf: Open blink!\n");
if(!blink_flag){
my_timer.expires = jiffies + HZ;
add_timer(&my_timer);
}
blink_flag = true;
} else {
printk(KERN_INFO "Wangyf: Close blink!\n");
del_timer(&my_timer);
blink_flag = false;
}
return blink_status;
}
DEVICE_ATTR(blink,0666,NULL,blink_gpio);
static struct attribute *my_led_attribute[] = {
&dev_attr_blink.attr,
NULL
};
生成blink文件节点，使用命令
echo 1 > blink
灯会闪烁，但是会有输出：
bash: echo: write error: Success
使用命令
echo 0 > blink
会进入不停的循环，dmesg结果：
[ 2309.131709] Wangyf: blink get order from echo!
[ 2309.131715] Wangyf: blink_status = 0
[ 2309.131720] Wangyf: Close blink!
[ 2309.131726] Wangyf: blink get order from echo!
[ 2309.131732] Wangyf: blink_status = 0
[ 2309.131737] Wangyf: Close blink!
[ 2309.131744] Wangyf: blink get order from echo!
[ 2309.131750] Wangyf: blink_status = 0
[ 2309.131755] Wangyf: Close blink!
[ 2309.131762] Wangyf: blink get order from echo!
[ 2309.131768] Wangyf: blink_status = 0
[ 2309.131774] Wangyf: Close blink!
[ 2309.131781] Wangyf: blink get order from echo!
[ 2309.131786] Wangyf: blink_status = 0
[ 2309.131791] Wangyf: Close blink!
[ 2309.131797] Wangyf: blink get order from echo!
[ 2309.131802] Wangyf: blink_status = 0
[ 2309.131806] Wangyf: Close blink!
[ 2309.131811] Wangyf: blink get order from echo!
[ 2309.131816] Wangyf: blink_status = 0
[ 2309.131820] Wangyf: Close blink!
[ 2309.131826] Wangyf: blink get order from echo!
[ 2309.131830] Wangyf: blink_status = 0
probe函数中：
init_timer(&my_timer);
my_timer.function = change_status;
my_timer.expires = jiffies + HZ;
如果设置 2 为关闭blink就正常，这是为什么呢？
