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authorJohn Stultz <john.stultz@linaro.org>2011-02-11 17:45:40 -0800
committerJohn Stultz <john.stultz@linaro.org>2011-02-17 14:59:41 -0800
commit6e57b1d6a8d8ed1998229b71c102be1997e397c6 (patch)
tree941ae7ba1c168af5603bb47d3bbfba33a8f2760c /drivers/rtc
parent516373b8b60fa4152334b6b6f2ece0f178c540ce (diff)
downloadlinux-2.6.38-lt-ux500-6e57b1d6a8d8ed1998229b71c102be1997e397c6.tar.gz
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: 042620a018afcfba1d678062b62e46 - Remove UIE emulation 1daeddd5962acad1bea55e524fc0fa - Cleanup removed UIE emulation declaration b5cc8ca1c9c3a37eaddf709b2fd3e1 - 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>
Diffstat (limited to 'drivers/rtc')
-rw-r--r--drivers/rtc/Kconfig12
-rw-r--r--drivers/rtc/rtc-dev.c104
2 files changed, 116 insertions, 0 deletions
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index cdd97192dc6..4941cade319 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -97,6 +97,18 @@ config RTC_INTF_DEV
If unsure, say Y.
+config RTC_INTF_DEV_UIE_EMUL
+ bool "RTC UIE emulation on dev interface"
+ depends on RTC_INTF_DEV
+ help
+ Provides an emulation for RTC_UIE if the underlying rtc chip
+ driver does not expose RTC_UIE ioctls. Those requests generate
+ once-per-second update interrupts, used for synchronization.
+
+ The emulation code will read the time from the hardware
+ clock several times per second, please enable this option
+ only if you know that you really need it.
+
config RTC_DRV_TEST
tristate "Test driver/device"
help
diff --git a/drivers/rtc/rtc-dev.c b/drivers/rtc/rtc-dev.c
index 37c3cc1b3dd..dfa72c9c268 100644
--- a/drivers/rtc/rtc-dev.c
+++ b/drivers/rtc/rtc-dev.c
@@ -46,6 +46,105 @@ static int rtc_dev_open(struct inode *inode, struct file *file)
return err;
}
+#ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
+/*
+ * Routine to poll RTC seconds field for change as often as possible,
+ * after first RTC_UIE use timer to reduce polling
+ */
+static void rtc_uie_task(struct work_struct *work)
+{
+ struct rtc_device *rtc =
+ container_of(work, struct rtc_device, uie_task);
+ struct rtc_time tm;
+ int num = 0;
+ int err;
+
+ err = rtc_read_time(rtc, &tm);
+
+ spin_lock_irq(&rtc->irq_lock);
+ if (rtc->stop_uie_polling || err) {
+ rtc->uie_task_active = 0;
+ } else if (rtc->oldsecs != tm.tm_sec) {
+ num = (tm.tm_sec + 60 - rtc->oldsecs) % 60;
+ rtc->oldsecs = tm.tm_sec;
+ rtc->uie_timer.expires = jiffies + HZ - (HZ/10);
+ rtc->uie_timer_active = 1;
+ rtc->uie_task_active = 0;
+ add_timer(&rtc->uie_timer);
+ } else if (schedule_work(&rtc->uie_task) == 0) {
+ rtc->uie_task_active = 0;
+ }
+ spin_unlock_irq(&rtc->irq_lock);
+ if (num)
+ rtc_update_irq(rtc, num, RTC_UF | RTC_IRQF);
+}
+static void rtc_uie_timer(unsigned long data)
+{
+ struct rtc_device *rtc = (struct rtc_device *)data;
+ unsigned long flags;
+
+ spin_lock_irqsave(&rtc->irq_lock, flags);
+ rtc->uie_timer_active = 0;
+ rtc->uie_task_active = 1;
+ if ((schedule_work(&rtc->uie_task) == 0))
+ rtc->uie_task_active = 0;
+ spin_unlock_irqrestore(&rtc->irq_lock, flags);
+}
+
+static int clear_uie(struct rtc_device *rtc)
+{
+ spin_lock_irq(&rtc->irq_lock);
+ if (rtc->uie_irq_active) {
+ rtc->stop_uie_polling = 1;
+ if (rtc->uie_timer_active) {
+ spin_unlock_irq(&rtc->irq_lock);
+ del_timer_sync(&rtc->uie_timer);
+ spin_lock_irq(&rtc->irq_lock);
+ rtc->uie_timer_active = 0;
+ }
+ if (rtc->uie_task_active) {
+ spin_unlock_irq(&rtc->irq_lock);
+ flush_scheduled_work();
+ spin_lock_irq(&rtc->irq_lock);
+ }
+ rtc->uie_irq_active = 0;
+ }
+ spin_unlock_irq(&rtc->irq_lock);
+ return 0;
+}
+
+static int set_uie(struct rtc_device *rtc)
+{
+ struct rtc_time tm;
+ int err;
+
+ err = rtc_read_time(rtc, &tm);
+ if (err)
+ return err;
+ spin_lock_irq(&rtc->irq_lock);
+ if (!rtc->uie_irq_active) {
+ rtc->uie_irq_active = 1;
+ rtc->stop_uie_polling = 0;
+ rtc->oldsecs = tm.tm_sec;
+ rtc->uie_task_active = 1;
+ if (schedule_work(&rtc->uie_task) == 0)
+ rtc->uie_task_active = 0;
+ }
+ rtc->irq_data = 0;
+ spin_unlock_irq(&rtc->irq_lock);
+ return 0;
+}
+
+int rtc_dev_update_irq_enable_emul(struct rtc_device *rtc, unsigned int enabled)
+{
+ if (enabled)
+ return set_uie(rtc);
+ else
+ return clear_uie(rtc);
+}
+EXPORT_SYMBOL(rtc_dev_update_irq_enable_emul);
+
+#endif /* CONFIG_RTC_INTF_DEV_UIE_EMUL */
static ssize_t
rtc_dev_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
@@ -387,6 +486,11 @@ void rtc_dev_prepare(struct rtc_device *rtc)
rtc->dev.devt = MKDEV(MAJOR(rtc_devt), rtc->id);
+#ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
+ INIT_WORK(&rtc->uie_task, rtc_uie_task);
+ setup_timer(&rtc->uie_timer, rtc_uie_timer, (unsigned long)rtc);
+#endif
+
cdev_init(&rtc->char_dev, &rtc_dev_fops);
rtc->char_dev.owner = rtc->owner;
}