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Subject[PATCH v4 1/2] rtc-cmos: Clear ACPI-driven alarms upon resume
Date
Currently ACPI-driven alarms are not cleared when they wake the
system. As consequence, expired alarms must be manually cleared to
program a new alarm. Fix this by correctly handling ACPI-driven
alarms.

More specifically, the ACPI specification [1] provides for two
alternative implementations of the RTC. Depending on the
implementation, the driver either clear the alarm from the resume
callback or from ACPI interrupt handler:

- The platform has the RTC wakeup status fixed in hardware
(ACPI_FADT_FIXED_RTC is 0). In this case the driver can determine
if the RTC was the reason of the wakeup from the resume callback
by reading the RTC status register.

- The platform has no fixed hardware feature event bits. In this
case a GPE is used to wake the system and the driver clears the
alarm from its handler.

[1] http://www.acpi.info/DOWNLOADS/ACPI_5_Errata%20A.pdf

Signed-off-by: Gabriele Mazzotta <gabriele.mzt@gmail.com>
---
drivers/rtc/rtc-cmos.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 49 insertions(+)

diff --git a/drivers/rtc/rtc-cmos.c b/drivers/rtc/rtc-cmos.c
index 1dec52f..fd7ec0a 100644
--- a/drivers/rtc/rtc-cmos.c
+++ b/drivers/rtc/rtc-cmos.c
@@ -900,6 +900,9 @@ static inline int cmos_poweroff(struct device *dev)

#ifdef CONFIG_PM_SLEEP

+static void cmos_check_acpi_rtc_status(struct device *dev,
+ unsigned char *rtc_control);
+
static int cmos_resume(struct device *dev)
{
struct cmos_rtc *cmos = dev_get_drvdata(dev);
@@ -939,6 +942,9 @@ static int cmos_resume(struct device *dev)
tmp &= ~RTC_AIE;
hpet_mask_rtc_irq_bit(RTC_AIE);
} while (mask & RTC_AIE);
+
+ if (tmp & RTC_AIE)
+ cmos_check_acpi_rtc_status(dev, &tmp);
}
spin_unlock_irq(&rtc_lock);

@@ -976,6 +982,22 @@ static SIMPLE_DEV_PM_OPS(cmos_pm_ops, cmos_suspend, cmos_resume);
static u32 rtc_handler(void *context)
{
struct device *dev = context;
+ struct cmos_rtc *cmos = dev_get_drvdata(dev);
+ unsigned char rtc_control;
+ unsigned char rtc_intr;
+
+ spin_lock_irq(&rtc_lock);
+ if (!cmos_rtc.suspend_ctrl)
+ rtc_control = cmos_rtc.suspend_ctrl;
+ else
+ rtc_control = CMOS_READ(RTC_CONTROL);
+ if (rtc_control & RTC_AIE) {
+ cmos_rtc.suspend_ctrl &= ~RTC_AIE;
+ CMOS_WRITE(rtc_control, RTC_CONTROL);
+ rtc_intr = CMOS_READ(RTC_INTR_FLAGS);
+ rtc_update_irq(cmos->rtc, 1, rtc_intr);
+ }
+ spin_unlock_irq(&rtc_lock);

pm_wakeup_event(dev, 0);
acpi_clear_event(ACPI_EVENT_RTC);
@@ -1042,12 +1064,39 @@ static void cmos_wake_setup(struct device *dev)
device_init_wakeup(dev, 1);
}

+static void cmos_check_acpi_rtc_status(struct device *dev,
+ unsigned char *rtc_control)
+{
+ struct cmos_rtc *cmos = dev_get_drvdata(dev);
+ acpi_event_status rtc_status;
+ acpi_status status;
+
+ if (acpi_gbl_FADT.flags & ACPI_FADT_FIXED_RTC)
+ return;
+
+ status = acpi_get_event_status(ACPI_EVENT_RTC, &rtc_status);
+ if (ACPI_FAILURE(status)) {
+ dev_err(dev, "Could not get RTC status\n");
+ } else if (rtc_status & ACPI_EVENT_FLAG_SET) {
+ unsigned char mask;
+ *rtc_control &= ~RTC_AIE;
+ CMOS_WRITE(*rtc_control, RTC_CONTROL);
+ mask = CMOS_READ(RTC_INTR_FLAGS);
+ rtc_update_irq(cmos->rtc, 1, mask);
+ }
+}
+
#else

static void cmos_wake_setup(struct device *dev)
{
}

+static void cmos_check_acpi_rtc_status(struct device *dev,
+ unsigned char *rtc_control)
+{
+}
+
#endif

#ifdef CONFIG_PNP
--
2.9.3
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