static unsigned int ls_poll(struct file *filp, poll_table *wait)
{
unsigned int mask = 0;
#if DEBUG
printk("%s poll request\n", DEV_NAME);
#endif
mutex_lock(&ls.update_lock);
poll_wait(filp, &waitQ, wait);
if (!(ls.state & (LS_DATA_READY | LS_ANY_RESULT) ||
check_sensor_value())) {
mod_timer(&ls.tmr, jiffies + msecs_to_jiffies(ls.conf.poll_period_ms));
goto data_not_ready;
}
#if DEBUG
printk("%s poll request - data ready\n", DEV_NAME);
#endif
mask |= POLLIN | POLLRDNORM; /* readable */
data_not_ready:
mutex_unlock(&ls.update_lock);
return mask;
}
static ssize_t ls_read(struct file *file, char __user *buf,
size_t count, loff_t *offset)
{
int ok;
#if DEBUG
printk("%s read request.\n", DEV_NAME);
#endif
mutex_lock(&ls.update_lock);
if (ls.state & LS_SUSPEND) {
#if DEBUG
printk(KERN_ERR "%s: is suspended!\n", DEV_NAME);
#endif
mutex_unlock(&ls.update_lock);
return -EBUSY;
}
ok = check_sensor_value();
if (ok || ls.state & LS_ANY_RESULT)
goto data_ready;
if (file->f_flags & O_NONBLOCK) {
mutex_unlock(&ls.update_lock);
return -EAGAIN;
}
mod_timer(&ls.tmr, jiffies + msecs_to_jiffies(ls.conf.poll_period_ms));
mutex_unlock(&ls.update_lock);
#if DEBUG
printk("%s read request in a wait queue\n", DEV_NAME);
#endif
if (-ERESTARTSYS ==
wait_event_interruptible(waitQ, ls.state & LS_DATA_READY))
return -ERESTARTSYS;
mutex_lock(&ls.update_lock);
data_ready:
#if DEBUG
printk("%s sensor value %d\n", DEV_NAME, ls.sensor_value);
#endif
ls.state &= ~LS_DATA_READY;
ok = count >= sizeof(ls.sensor_value) &&
!copy_to_user(buf, &ls.sensor_value, sizeof(ls.sensor_value));
ok = ok ? sizeof(ls.sensor_value) : -EFAULT;
mutex_unlock(&ls.update_lock);
return ok;
}
static void timer_bh(struct work_struct *work)
{
mutex_lock(&ls.update_lock);
if (!(ls.state & LS_SUSPEND)) {
if (check_sensor_value()) {
wake_up_interruptible(&waitQ);
goto out;
}
if (ls.state & LS_DEVICE_OPENED && !(ls.state & LS_DATA_READY))
mod_timer(&ls.tmr, jiffies +
msecs_to_jiffies(ls.conf.poll_period_ms));
}
out:
mutex_unlock(&ls.update_lock);
}