Linux 内核时钟架构之时钟事件设备注册

void clockevents_register_device(struct clock_event_device *dev);
 
void clockevents_config_and_register(struct clock_event_device *dev,
         u32 freq, unsigned long min_delta,
         unsigned long max_delta);
 
 
 
 
 
相关的一个是配置函数
 
void clockevents_config(struct clock_event_device *dev, u32 freq);
 
 
 
 
 
 
 
/**
 * clockevents_register_device - register a clock event device
 * @dev: device to register
 */
void clockevents_register_device(struct clock_event_device *dev)
{
 unsigned long flags;
 /* Initialize state to DETACHED */
 clockevent_set_state(dev, CLOCK_EVT_STATE_DETACHED);
 if (!dev->cpumask) {
  WARN_ON(num_possible_cpus() > 1);
  dev->cpumask = cpumask_of(smp_processor_id());
 }
 raw_spin_lock_irqsave(&clockevents_lock, flags);
 list_add(&dev->list, &clockevent_devices);
 tick_check_new_device(dev);
 clockevents_notify_released();
 raw_spin_unlock_irqrestore(&clockevents_lock, flags);
}
EXPORT_SYMBOL_GPL(clockevents_register_device);
 
 
 
 
 
/**
 * clockevents_config_and_register - Configure and register a clock event device
 * @dev: device to register
 * @freq: The clock frequency
 * @min_delta: The minimum clock ticks to program in oneshot mode
 * @max_delta: The maximum clock ticks to program in oneshot mode
 *
 * min/max_delta can be 0 for devices which do not support oneshot mode.
 */
void clockevents_config_and_register(struct clock_event_device *dev,
         u32 freq, unsigned long min_delta,
         unsigned long max_delta)
{
 dev->min_delta_ticks = min_delta;
 dev->max_delta_ticks = max_delta;
 clockevents_config(dev, freq);
 clockevents_register_device(dev);
}
EXPORT_SYMBOL_GPL(clockevents_config_and_register);
 
 
 
 
 
 
 
 
 

void clockevents_config(struct clock_event_device *dev, u32 freq)
{
 u64 sec;
 if (!(dev->features & CLOCK_EVT_FEAT_ONESHOT))
  return;
 /*
  * Calculate the maximum number of seconds we can sleep. Limit
  * to 10 minutes for hardware which can program more than
  * 32bit ticks so we still get reasonable conversion values.
  */
 sec = dev->max_delta_ticks;
 do_div(sec, freq);
 if (!sec)
  sec = 1;
 else if (sec > 600 && dev->max_delta_ticks > UINT_MAX)
  sec = 600;
 clockevents_calc_mult_shift(dev, freq, sec);
 dev->min_delta_ns = cev_delta2ns(dev->min_delta_ticks, dev, false);
 dev->max_delta_ns = cev_delta2ns(dev->max_delta_ticks, dev, true);
}