[PATCH 04/24] rtc: pm8xxx: drop bogus locking

Johan Hovold
2023-01-26T14:23:29Z

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>
---
drivers/rtc/rtc-pm8xxx.c | 67 +++++++++++++---------------------------
1 file changed, 21 insertions(+), 46 deletions(-)

diff --git a/drivers/rtc/rtc-pm8xxx.c b/drivers/rtc/rtc-pm8xxx.c
index 8c2847ac64f4..053a04f74a91 100644
--- 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");
--
2.39.1