rtc: pm8xxx: drop bogus locking

Since commit c8d523a4b053 ("drivers/rtc/rtc-pm8xxx.c: rework to support
pm8941 rtc") which removed the shadow control register there is no need
for a driver lock.

Specifically, the rtc ops are serialised by rtc core and the interrupt
handler only unconditionally disables the alarm using the alarm_ctrl
register.

Note that since only the alarm enable bit of alarm_ctrl is used after
enabling the RTC at probe, the locking was not needed when doing open
coded read-modify-write cycles either.

Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Reviewed-by: David Collins <quic_collinsd@quicinc.com>
Link: https://lore.kernel.org/r/20230202155448.6715-5-johan+linaro@kernel.org
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

diff --git a/drivers/rtc/rtc-pm8xxx.c b/drivers/rtc/rtc-pm8xxx.c
index 8c2847a..053a04f 100644 (file)
--- a/drivers/rtc/rtc-pm8xxx.c
+++ b/drivers/rtc/rtc-pm8xxx.c
@@ -53,7 +53,6 @@ struct pm8xxx_rtc_regs {
  * @rtc_alarm_irq:     rtc alarm irq number.
  * @regs:              rtc registers description.
  * @rtc_dev:           device structure.
- * @ctrl_reg_lock:     spinlock protecting access to ctrl_reg.
  */
 struct pm8xxx_rtc {
        struct rtc_device *rtc;
@@ -62,7 +61,6 @@ struct pm8xxx_rtc {
        int rtc_alarm_irq;
        const struct pm8xxx_rtc_regs *regs;
        struct device *rtc_dev;
-       spinlock_t ctrl_reg_lock;
 };
 
 /*
@@ -77,11 +75,11 @@ struct pm8xxx_rtc {
 static int pm8xxx_rtc_set_time(struct device *dev, struct rtc_time *tm)
 {
        int rc, i;
-       unsigned long secs, irq_flags;
        struct pm8xxx_rtc *rtc_dd = dev_get_drvdata(dev);
        const struct pm8xxx_rtc_regs *regs = rtc_dd->regs;
        u8 value[NUM_8_BIT_RTC_REGS];
        bool alarm_enabled;
+       unsigned long secs;
 
        if (!rtc_dd->allow_set_time)
                return -ENODEV;
@@ -95,51 +93,46 @@ static int pm8xxx_rtc_set_time(struct device *dev, struct rtc_time *tm)
                secs >>= 8;
        }
 
-       spin_lock_irqsave(&rtc_dd->ctrl_reg_lock, irq_flags);
-
        rc = regmap_update_bits_check(rtc_dd->regmap, regs->alarm_ctrl,
                                      regs->alarm_en, 0, &alarm_enabled);
        if (rc)
-               goto rtc_rw_fail;
+               return rc;
 
        /* Disable RTC H/w before writing on RTC register */
        rc = regmap_update_bits(rtc_dd->regmap, regs->ctrl, PM8xxx_RTC_ENABLE, 0);
        if (rc)
-               goto rtc_rw_fail;
+               return rc;
 
        /* Write 0 to Byte[0] */
        rc = regmap_write(rtc_dd->regmap, regs->write, 0);
        if (rc)
-               goto rtc_rw_fail;
+               return rc;
 
        /* Write Byte[1], Byte[2], Byte[3] */
        rc = regmap_bulk_write(rtc_dd->regmap, regs->write + 1,
                               &value[1], sizeof(value) - 1);
        if (rc)
-               goto rtc_rw_fail;
+               return rc;
 
        /* Write Byte[0] */
        rc = regmap_write(rtc_dd->regmap, regs->write, value[0]);
        if (rc)
-               goto rtc_rw_fail;
+               return rc;
 
        /* Enable RTC H/w after writing on RTC register */
        rc = regmap_update_bits(rtc_dd->regmap, regs->ctrl, PM8xxx_RTC_ENABLE,
                                PM8xxx_RTC_ENABLE);
        if (rc)
-               goto rtc_rw_fail;
+               return rc;
 
        if (alarm_enabled) {
                rc = regmap_update_bits(rtc_dd->regmap, regs->alarm_ctrl,
                                        regs->alarm_en, regs->alarm_en);
                if (rc)
-                       goto rtc_rw_fail;
+                       return rc;
        }
 
-rtc_rw_fail:
-       spin_unlock_irqrestore(&rtc_dd->ctrl_reg_lock, irq_flags);
-
-       return rc;
+       return 0;
 }
 
 static int pm8xxx_rtc_read_time(struct device *dev, struct rtc_time *tm)
@@ -184,9 +177,9 @@ static int pm8xxx_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 {
        int rc, i;
        u8 value[NUM_8_BIT_RTC_REGS];
-       unsigned long secs, irq_flags;
        struct pm8xxx_rtc *rtc_dd = dev_get_drvdata(dev);
        const struct pm8xxx_rtc_regs *regs = rtc_dd->regs;
+       unsigned long secs;
 
        secs = rtc_tm_to_time64(&alarm->time);
 
@@ -200,25 +193,22 @@ static int pm8xxx_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
        if (rc)
                return rc;
 
-       spin_lock_irqsave(&rtc_dd->ctrl_reg_lock, irq_flags);
-
        rc = regmap_bulk_write(rtc_dd->regmap, regs->alarm_rw, value,
                               sizeof(value));
        if (rc)
-               goto rtc_rw_fail;
+               return rc;
 
        if (alarm->enabled) {
                rc = regmap_update_bits(rtc_dd->regmap, regs->alarm_ctrl,
                                        regs->alarm_en, regs->alarm_en);
                if (rc)
-                       goto rtc_rw_fail;
+                       return rc;
        }
 
        dev_dbg(dev, "Alarm Set for h:m:s=%ptRt, y-m-d=%ptRdr\n",
                &alarm->time, &alarm->time);
-rtc_rw_fail:
-       spin_unlock_irqrestore(&rtc_dd->ctrl_reg_lock, irq_flags);
-       return rc;
+
+       return 0;
 }
 
 static int pm8xxx_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
@@ -255,14 +245,11 @@ static int pm8xxx_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 static int pm8xxx_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
 {
        int rc;
-       unsigned long irq_flags;
        struct pm8xxx_rtc *rtc_dd = dev_get_drvdata(dev);
        const struct pm8xxx_rtc_regs *regs = rtc_dd->regs;
        u8 value[NUM_8_BIT_RTC_REGS] = {0};
        unsigned int val;
 
-       spin_lock_irqsave(&rtc_dd->ctrl_reg_lock, irq_flags);
-
        if (enable)
                val = regs->alarm_en;
        else
@@ -271,19 +258,17 @@ static int pm8xxx_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
        rc = regmap_update_bits(rtc_dd->regmap, regs->alarm_ctrl,
                                regs->alarm_en, val);
        if (rc)
-               goto rtc_rw_fail;
+               return rc;
 
        /* Clear Alarm register */
        if (!enable) {
                rc = regmap_bulk_write(rtc_dd->regmap, regs->alarm_rw, value,
                                       sizeof(value));
                if (rc)
-                       goto rtc_rw_fail;
+                       return rc;
        }
 
-rtc_rw_fail:
-       spin_unlock_irqrestore(&rtc_dd->ctrl_reg_lock, irq_flags);
-       return rc;
+       return 0;
 }
 
 static const struct rtc_class_ops pm8xxx_rtc_ops = {
@@ -302,25 +287,18 @@ static irqreturn_t pm8xxx_alarm_trigger(int irq, void *dev_id)
 
        rtc_update_irq(rtc_dd->rtc, 1, RTC_IRQF | RTC_AF);
 
-       spin_lock(&rtc_dd->ctrl_reg_lock);
-
        /* Clear the alarm enable bit */
        rc = regmap_update_bits(rtc_dd->regmap, regs->alarm_ctrl,
                                regs->alarm_en, 0);
-       if (rc) {
-               spin_unlock(&rtc_dd->ctrl_reg_lock);
-               goto rtc_alarm_handled;
-       }
-
-       spin_unlock(&rtc_dd->ctrl_reg_lock);
+       if (rc)
+               goto out;
 
        /* Clear RTC alarm register */
        rc = regmap_update_bits(rtc_dd->regmap, regs->alarm_ctrl2,
                                PM8xxx_RTC_ALARM_CLEAR, 0);
        if (rc)
-               goto rtc_alarm_handled;
-
-rtc_alarm_handled:
+               goto out;
+out:
        return IRQ_HANDLED;
 }
 
@@ -398,9 +376,6 @@ static int pm8xxx_rtc_probe(struct platform_device *pdev)
        if (rtc_dd == NULL)
                return -ENOMEM;
 
-       /* Initialise spinlock to protect RTC control register */
-       spin_lock_init(&rtc_dd->ctrl_reg_lock);
-
        rtc_dd->regmap = dev_get_regmap(pdev->dev.parent, NULL);
        if (!rtc_dd->regmap) {
                dev_err(&pdev->dev, "Parent regmap unavailable.\n");