[PATCH 4.9 097/125] rtc: pm8xxx: Fix issue in RTC write path

From: Greg Kroah-Hartman
Date: Wed Apr 22 2020 - 06:08:23 EST


From: Mohit Aggarwal <maggarwa@xxxxxxxxxxxxxx>

[ Upstream commit 83220bf38b77a830f8e62ab1a0d0408304f9b966 ]

In order to set time in rtc, need to disable
rtc hw before writing into rtc registers.

Also fixes disabling of alarm while setting
rtc time.

Signed-off-by: Mohit Aggarwal <maggarwa@xxxxxxxxxxxxxx>
Signed-off-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx>
Signed-off-by: Lee Jones <lee.jones@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/rtc/rtc-pm8xxx.c | 49 ++++++++++++++++++++++++++++++++++++-----------
1 file changed, 38 insertions(+), 11 deletions(-)

--- a/drivers/rtc/rtc-pm8xxx.c
+++ b/drivers/rtc/rtc-pm8xxx.c
@@ -74,16 +74,18 @@ struct pm8xxx_rtc {
/*
* Steps to write the RTC registers.
* 1. Disable alarm if enabled.
- * 2. Write 0x00 to LSB.
- * 3. Write Byte[1], Byte[2], Byte[3] then Byte[0].
- * 4. Enable alarm if disabled in step 1.
+ * 2. Disable rtc if enabled.
+ * 3. Write 0x00 to LSB.
+ * 4. Write Byte[1], Byte[2], Byte[3] then Byte[0].
+ * 5. Enable rtc if disabled in step 2.
+ * 6. Enable alarm if disabled in step 1.
*/
static int pm8xxx_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
int rc, i;
unsigned long secs, irq_flags;
- u8 value[NUM_8_BIT_RTC_REGS], alarm_enabled = 0;
- unsigned int ctrl_reg;
+ u8 value[NUM_8_BIT_RTC_REGS], alarm_enabled = 0, rtc_disabled = 0;
+ unsigned int ctrl_reg, rtc_ctrl_reg;
struct pm8xxx_rtc *rtc_dd = dev_get_drvdata(dev);
const struct pm8xxx_rtc_regs *regs = rtc_dd->regs;

@@ -92,23 +94,38 @@ static int pm8xxx_rtc_set_time(struct de

rtc_tm_to_time(tm, &secs);

+ dev_dbg(dev, "Seconds value to be written to RTC = %lu\n", secs);
+
for (i = 0; i < NUM_8_BIT_RTC_REGS; i++) {
value[i] = secs & 0xFF;
secs >>= 8;
}

- dev_dbg(dev, "Seconds value to be written to RTC = %lu\n", secs);
-
spin_lock_irqsave(&rtc_dd->ctrl_reg_lock, irq_flags);

- rc = regmap_read(rtc_dd->regmap, regs->ctrl, &ctrl_reg);
+ rc = regmap_read(rtc_dd->regmap, regs->alarm_ctrl, &ctrl_reg);
if (rc)
goto rtc_rw_fail;

if (ctrl_reg & regs->alarm_en) {
alarm_enabled = 1;
ctrl_reg &= ~regs->alarm_en;
- rc = regmap_write(rtc_dd->regmap, regs->ctrl, ctrl_reg);
+ rc = regmap_write(rtc_dd->regmap, regs->alarm_ctrl, ctrl_reg);
+ if (rc) {
+ dev_err(dev, "Write to RTC Alarm control register failed\n");
+ goto rtc_rw_fail;
+ }
+ }
+
+ /* Disable RTC H/w before writing on RTC register */
+ rc = regmap_read(rtc_dd->regmap, regs->ctrl, &rtc_ctrl_reg);
+ if (rc)
+ goto rtc_rw_fail;
+
+ if (rtc_ctrl_reg & PM8xxx_RTC_ENABLE) {
+ rtc_disabled = 1;
+ rtc_ctrl_reg &= ~PM8xxx_RTC_ENABLE;
+ rc = regmap_write(rtc_dd->regmap, regs->ctrl, rtc_ctrl_reg);
if (rc) {
dev_err(dev, "Write to RTC control register failed\n");
goto rtc_rw_fail;
@@ -137,11 +154,21 @@ static int pm8xxx_rtc_set_time(struct de
goto rtc_rw_fail;
}

+ /* Enable RTC H/w after writing on RTC register */
+ if (rtc_disabled) {
+ rtc_ctrl_reg |= PM8xxx_RTC_ENABLE;
+ rc = regmap_write(rtc_dd->regmap, regs->ctrl, rtc_ctrl_reg);
+ if (rc) {
+ dev_err(dev, "Write to RTC control register failed\n");
+ goto rtc_rw_fail;
+ }
+ }
+
if (alarm_enabled) {
ctrl_reg |= regs->alarm_en;
- rc = regmap_write(rtc_dd->regmap, regs->ctrl, ctrl_reg);
+ rc = regmap_write(rtc_dd->regmap, regs->alarm_ctrl, ctrl_reg);
if (rc) {
- dev_err(dev, "Write to RTC control register failed\n");
+ dev_err(dev, "Write to RTC Alarm control register failed\n");
goto rtc_rw_fail;
}
}