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我试图编写 i2c 设备驱动程序，一切都很好：

  1. 成功检测到设备
  2. sysfs 类中的设备也创建了 value 属性
  3. 然后我初始化一个 hrtimer 并启动它
  4. 我正在尝试从属性的存储功能发送数据，它工作正常

但是当我尝试从 hrtimer 回调函数发送数据时，我的系统出现故障。这是一些代码（我删除了包含、定义和不重要的代码）：

led-indicator.h

struct timer_job {
        ktime_t period;
        struct hrtimer timer;
        ...
};

struct ledindicator {
        struct i2c_client *client;
        struct device *device;
        struct timer_job job;
        int value;
};

led-indicator.c

include "led-indicator.h"
static struct ledindicator *li;

// device attribute [value] store function
static ssize_t value_store(struct device *device, struct device_attribute *attr, const char *buffer, size_t count)
{
    int val;
    kstrtoint(buffer, 10, &val);
    li->value = val;
    i2c_smbus_write_byte_data(li->client,  0xBA, 0x02); // this is work fine
    LOG("New value is %d \n", li->value);
    return count;
}

//timer callback, fire each timer_job.period
static enum hrtimer_restart send_next(struct hrtimer * tim) {
    long start = jiffies;
    struct timer_job *job = container_of(tim, struct timer_job, timer);
    i2c_smbus_write_byte_data(li->client, 0xBA, 0x02); // this cause system fault
    hrtimer_forward_now(tim, job->period);
    return HRTIMER_RESTART;
}

//when device is detected I am create sysfs device and init timer. 
enter code here//Also I am crate led_indicator structure and save i2c_client pointer for future use
static int li_probe(struct i2c_client *client, const struct i2c_device_id *id)
{
    int ret = 0;
    li = kmalloc(sizeof(*li), GFP_KERNEL);
    li->client = client;
    li->value = 0;

    ...
    // here creating device and attribute for it
    ...

    hrtimer_init(&(li->job.timer), CLOCK_MONOTONIC, HRTIMER_MODE_REL);

    li->job.timer.function = send_next;
    li->job.period = ktime_set(1, 0); //1 sec
    hrtimer_start(&(li->job.timer), li->job.period, HRTIMER_MODE_REL);

    return ret;
}

怎么了？

4

0 回答 0