[PATCH v5 2/2] rtc: omap: Cut down the shutdown time from 2 seconds to 1 sec

From: Keerthy
Date: Wed Jul 25 2018 - 01:52:12 EST


Cut down the shutdown time from 2 seconds to 1 sec. In case of roll
over try again.

Signed-off-by: Keerthy <j-keerthy@xxxxxx>
---

Changes in v5:

* Added an additional check to see if ALARM2 status is not set
before retrying.
* Cleaned up comments
* Also reduced mdelay to 1S lesser as per this commit

drivers/rtc/rtc-omap.c | 28 ++++++++++++++++++----------
1 file changed, 18 insertions(+), 10 deletions(-)

diff --git a/drivers/rtc/rtc-omap.c b/drivers/rtc/rtc-omap.c
index 44ff4cc..caa6da6 100644
--- a/drivers/rtc/rtc-omap.c
+++ b/drivers/rtc/rtc-omap.c
@@ -421,12 +421,6 @@ static int omap_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
* The RTC can be used to control an external PMIC via the pmic_power_en pin,
* which can be configured to transition to OFF on ALARM2 events.
*
- * Notes:
- * The two-second alarm offset is the shortest offset possible as the alarm
- * registers must be set before the next timer update and the offset
- * calculation is too heavy for everything to be done within a single access
- * period (~15 us).
- *
* Called with local interrupts disabled.
*/
static void omap_rtc_power_off(void)
@@ -435,17 +429,20 @@ static void omap_rtc_power_off(void)
struct rtc_time tm;
unsigned long now;
u32 val;
+ int seconds;

rtc->type->unlock(rtc);
/* enable pmic_power_en control */
val = rtc_readl(rtc, OMAP_RTC_PMIC_REG);
rtc_writel(rtc, OMAP_RTC_PMIC_REG, val | OMAP_RTC_PMIC_POWER_EN_EN);

- /* set alarm two seconds from now */
+again:
+ /* set alarm one second from now */
omap_rtc_read_time_raw(rtc, &tm);
+ seconds = tm.tm_sec;
bcd2tm(&tm);
rtc_tm_to_time(&tm, &now);
- rtc_time_to_tm(now + 2, &tm);
+ rtc_time_to_tm(now + 1, &tm);

if (tm2bcd(&tm) < 0) {
dev_err(&rtc->rtc->dev, "power off failed\n");
@@ -470,14 +467,25 @@ static void omap_rtc_power_off(void)
val = rtc_read(rtc, OMAP_RTC_INTERRUPTS_REG);
rtc_writel(rtc, OMAP_RTC_INTERRUPTS_REG,
val | OMAP_RTC_INTERRUPTS_IT_ALARM2);
+
+ /*
+ * first check if ALARM2 has fired, if not then check if
+ * our calculations started right before the rollover, try again
+ * in case of rollover
+ */
+ if (!(OMAP_RTC_STATUS_ALARM2 && rtc_read(omap_rtc_power_off_rtc,
+ OMAP_RTC_STATUS_REG)) &&
+ seconds != rtc_read(omap_rtc_power_off_rtc, OMAP_RTC_SECONDS_REG))
+ goto again;
+
rtc->type->lock(rtc);

/*
- * Wait for alarm to trigger (within two seconds) and external PMIC to
+ * Wait for alarm to trigger (within one second) and external PMIC to
* power off the system. Add a 500 ms margin for external latencies
* (e.g. debounce circuits).
*/
- mdelay(2500);
+ mdelay(1500);
}

static const struct rtc_class_ops omap_rtc_ops = {
--
1.9.1