RTC: Revert UIE emulation removal
Uwe pointed out that my alarm based UIE emulation is not sufficient to replace the older timer/polling based UIE emulation on devices where there is no alarm irq. This causes rtc devices without alarms to return -EINVAL to UIE ioctls. The fix is to re-instate the old timer/polling method for devices without alarm irqs. This patch reverts the following commits:042620a018
- Remove UIE emulation1daeddd596
- Cleanup removed UIE emulation declarationb5cc8ca1c9
- Remove Kconfig symbol for UIE emulation The emulation mode will still need to be wired-in with a following patch before it will work. CC: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> CC: Thomas Gleixner <tglx@linutronix.de> Reported-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
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@ -97,6 +97,18 @@ config RTC_INTF_DEV
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If unsure, say Y.
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config RTC_INTF_DEV_UIE_EMUL
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bool "RTC UIE emulation on dev interface"
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depends on RTC_INTF_DEV
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help
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Provides an emulation for RTC_UIE if the underlying rtc chip
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driver does not expose RTC_UIE ioctls. Those requests generate
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once-per-second update interrupts, used for synchronization.
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The emulation code will read the time from the hardware
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clock several times per second, please enable this option
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only if you know that you really need it.
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config RTC_DRV_TEST
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tristate "Test driver/device"
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help
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@ -46,6 +46,105 @@ static int rtc_dev_open(struct inode *inode, struct file *file)
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return err;
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}
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#ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
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/*
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* Routine to poll RTC seconds field for change as often as possible,
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* after first RTC_UIE use timer to reduce polling
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*/
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static void rtc_uie_task(struct work_struct *work)
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{
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struct rtc_device *rtc =
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container_of(work, struct rtc_device, uie_task);
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struct rtc_time tm;
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int num = 0;
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int err;
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err = rtc_read_time(rtc, &tm);
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spin_lock_irq(&rtc->irq_lock);
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if (rtc->stop_uie_polling || err) {
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rtc->uie_task_active = 0;
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} else if (rtc->oldsecs != tm.tm_sec) {
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num = (tm.tm_sec + 60 - rtc->oldsecs) % 60;
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rtc->oldsecs = tm.tm_sec;
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rtc->uie_timer.expires = jiffies + HZ - (HZ/10);
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rtc->uie_timer_active = 1;
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rtc->uie_task_active = 0;
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add_timer(&rtc->uie_timer);
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} else if (schedule_work(&rtc->uie_task) == 0) {
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rtc->uie_task_active = 0;
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}
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spin_unlock_irq(&rtc->irq_lock);
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if (num)
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rtc_update_irq(rtc, num, RTC_UF | RTC_IRQF);
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}
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static void rtc_uie_timer(unsigned long data)
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{
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struct rtc_device *rtc = (struct rtc_device *)data;
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unsigned long flags;
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spin_lock_irqsave(&rtc->irq_lock, flags);
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rtc->uie_timer_active = 0;
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rtc->uie_task_active = 1;
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if ((schedule_work(&rtc->uie_task) == 0))
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rtc->uie_task_active = 0;
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spin_unlock_irqrestore(&rtc->irq_lock, flags);
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}
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static int clear_uie(struct rtc_device *rtc)
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{
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spin_lock_irq(&rtc->irq_lock);
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if (rtc->uie_irq_active) {
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rtc->stop_uie_polling = 1;
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if (rtc->uie_timer_active) {
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spin_unlock_irq(&rtc->irq_lock);
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del_timer_sync(&rtc->uie_timer);
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spin_lock_irq(&rtc->irq_lock);
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rtc->uie_timer_active = 0;
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}
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if (rtc->uie_task_active) {
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spin_unlock_irq(&rtc->irq_lock);
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flush_scheduled_work();
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spin_lock_irq(&rtc->irq_lock);
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}
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rtc->uie_irq_active = 0;
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}
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spin_unlock_irq(&rtc->irq_lock);
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return 0;
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}
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static int set_uie(struct rtc_device *rtc)
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{
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struct rtc_time tm;
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int err;
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err = rtc_read_time(rtc, &tm);
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if (err)
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return err;
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spin_lock_irq(&rtc->irq_lock);
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if (!rtc->uie_irq_active) {
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rtc->uie_irq_active = 1;
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rtc->stop_uie_polling = 0;
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rtc->oldsecs = tm.tm_sec;
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rtc->uie_task_active = 1;
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if (schedule_work(&rtc->uie_task) == 0)
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rtc->uie_task_active = 0;
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}
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rtc->irq_data = 0;
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spin_unlock_irq(&rtc->irq_lock);
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return 0;
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}
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int rtc_dev_update_irq_enable_emul(struct rtc_device *rtc, unsigned int enabled)
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{
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if (enabled)
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return set_uie(rtc);
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else
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return clear_uie(rtc);
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}
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EXPORT_SYMBOL(rtc_dev_update_irq_enable_emul);
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#endif /* CONFIG_RTC_INTF_DEV_UIE_EMUL */
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static ssize_t
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rtc_dev_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
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@ -387,6 +486,11 @@ void rtc_dev_prepare(struct rtc_device *rtc)
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rtc->dev.devt = MKDEV(MAJOR(rtc_devt), rtc->id);
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#ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
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INIT_WORK(&rtc->uie_task, rtc_uie_task);
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setup_timer(&rtc->uie_timer, rtc_uie_timer, (unsigned long)rtc);
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#endif
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cdev_init(&rtc->char_dev, &rtc_dev_fops);
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rtc->char_dev.owner = rtc->owner;
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}
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@ -203,6 +203,18 @@ struct rtc_device
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struct hrtimer pie_timer; /* sub second exp, so needs hrtimer */
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int pie_enabled;
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struct work_struct irqwork;
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#ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
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struct work_struct uie_task;
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struct timer_list uie_timer;
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/* Those fields are protected by rtc->irq_lock */
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unsigned int oldsecs;
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unsigned int uie_irq_active:1;
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unsigned int stop_uie_polling:1;
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unsigned int uie_task_active:1;
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unsigned int uie_timer_active:1;
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#endif
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};
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#define to_rtc_device(d) container_of(d, struct rtc_device, dev)
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@ -235,6 +247,8 @@ extern int rtc_irq_set_freq(struct rtc_device *rtc,
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struct rtc_task *task, int freq);
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extern int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled);
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extern int rtc_alarm_irq_enable(struct rtc_device *rtc, unsigned int enabled);
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extern int rtc_dev_update_irq_enable_emul(struct rtc_device *rtc,
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unsigned int enabled);
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void rtc_aie_update_irq(void *private);
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void rtc_uie_update_irq(void *private);
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