i2c device driver. System down when try to send data - c

Question

I trying to write i2c device driver and all is gone fine:
device detected successfully
device in sysfs class with value attribute created too
then I init a hrtimer and start it
I am trying to send data from store function of attribute and it's work fine
but when I trying to send data from hrtimer callback function my system going down. Here is some code (i was remove incudes, defines and non-important code):
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;
}
What is wrong?