Linux内核定时器的使用

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内核定时器的结构体定义在include/linux/timer.h：

struct timer_list {/* * All fields that change during normal runtime grouped to the * same cacheline */struct list_head entry;unsigned long expires;struct tvec_base *base;void (*function)(unsigned long);unsigned long data;int slack;#ifdef CONFIG_TIMER_STATSint start_pid;void *start_site;char start_comm[16];#endif#ifdef CONFIG_LOCKDEPstruct lockdep_map lockdep_map;#endif};

只需初始化定时器的超时时间expires，超时调用函数function，data成员会作为定时器超时函数的参数传递，驱动可以用data来存储自己的私有数据结构地址。下面是定时器应用的一个实例：
驱动的私有数据结构：

struct msg21xx_ts_data {struct input_dev *input;struct hrtimer timer;struct work_struct work;int irq;struct dentry *dir;char *ts_info;u8 addr;int fw_major;int fw_minor;#ifdef CONFIG_FBstruct notifier_block fb_notif;#endifbool suspended;struct timer_list tp_timer;struct i2c_client *client;struct regulator *vdd;struct regulator *vcc_i2c;struct msg21xx_platform_data *pdata;struct workqueue_struct *msg21xx_wq;struct mutex msg21xx_mutex;};

驱动的probe函数：

static int msg21xx_ts_probe(struct i2c_client *client,            const struct i2c_device_id *id){    struct msg21xx_ts_data *data;        data = kzalloc(sizeof(struct msg21xx_ts_data), GFP_KERNEL);    if (!data) {        dev_err(&client->dev, "%s: Alloc mem fail!", __func__);        err = -ENOMEM;        goto exit;    }        init_timer(&data->tp_timer);    data->tp_timer.function = tp_timer_function;    data->tp_timer.data = (unsigned long)data;//    setup_timer(&tp_timer, tp_timer_function, (unsigned long)data);    add_timer(&data->tp_timer);    mod_timer(&data->tp_timer, jiffies+HZ * 2);}

调用init_timer初始化定时器，然后设置定时器的超时调用函数，data成员被初始化为驱动的私有数据结构的地址，最后调用add_timer将定时器加入内核，调用mod_timer后，定时器会在2秒后超时，tp_timer_function函数被调用，data作为函数的参数被传入，在tp_timer_function函数中，就可以操作驱动的硬件。

void tp_timer_function(unsigned long datap){struct msg21xx_ts_data *data = (struct msg21xx_ts_data *)datap;gpio_set_value_cansleep(data->pdata->home_gpio, 0);gpio_set_value_cansleep(data->pdata->return_gpio, 0);gpio_set_value_cansleep(data->pdata->system_gpio, 0);}

下面的三条语句可以用一条代替：setup_timer(&tp_timer, tp_timer_function, (unsigned long)data);

init_timer(&data->tp_timer);data->tp_timer.function = tp_timer_function;data->tp_timer.data = (unsigned long)data;

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