[PATCH 4.9 135/153] rtc: sun6i: Add some locking

Greg Kroah-Hartman
2017-03-10T10:47:53Z

From: Maxime Ripard <maxime.ripard@free-electrons.com>

commit a9422a19ce270a22fc520f2278fb7e80c58be508 upstream.

Some registers have a read-modify-write access pattern that are not atomic.

Add some locking to prevent from concurrent accesses.

Acked-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/rtc/rtc-sun6i.c | 17 +++++++++++++++--
1 file changed, 15 insertions(+), 2 deletions(-)

--- a/drivers/rtc/rtc-sun6i.c
+++ b/drivers/rtc/rtc-sun6i.c
@@ -114,13 +114,17 @@ struct sun6i_rtc_dev {
void __iomem *base;
int irq;
unsigned long alarm;
+
+ spinlock_t lock;
};

static irqreturn_t sun6i_rtc_alarmirq(int irq, void *id)
{
struct sun6i_rtc_dev *chip = (struct sun6i_rtc_dev *) id;
+ irqreturn_t ret = IRQ_NONE;
u32 val;

+ spin_lock(&chip->lock);
val = readl(chip->base + SUN6I_ALRM_IRQ_STA);

if (val & SUN6I_ALRM_IRQ_STA_CNT_IRQ_PEND) {
@@ -129,10 +133,11 @@ static irqreturn_t sun6i_rtc_alarmirq(in

rtc_update_irq(chip->rtc, 1, RTC_AF | RTC_IRQF);

- return IRQ_HANDLED;
+ ret = IRQ_HANDLED;
}
+ spin_unlock(&chip->lock);

- return IRQ_NONE;
+ return ret;
}

static void sun6i_rtc_setaie(int to, struct sun6i_rtc_dev *chip)
@@ -140,6 +145,7 @@ static void sun6i_rtc_setaie(int to, str
u32 alrm_val = 0;
u32 alrm_irq_val = 0;
u32 alrm_wake_val = 0;
+ unsigned long flags;

if (to) {
alrm_val = SUN6I_ALRM_EN_CNT_EN;
@@ -150,9 +156,11 @@ static void sun6i_rtc_setaie(int to, str
chip->base + SUN6I_ALRM_IRQ_STA);
}

+ spin_lock_irqsave(&chip->lock, flags);
writel(alrm_val, chip->base + SUN6I_ALRM_EN);
writel(alrm_irq_val, chip->base + SUN6I_ALRM_IRQ_EN);
writel(alrm_wake_val, chip->base + SUN6I_ALARM_CONFIG);
+ spin_unlock_irqrestore(&chip->lock, flags);
}

static int sun6i_rtc_gettime(struct device *dev, struct rtc_time *rtc_tm)
@@ -191,11 +199,15 @@ static int sun6i_rtc_gettime(struct devi
static int sun6i_rtc_getalarm(struct device *dev, struct rtc_wkalrm *wkalrm)
{
struct sun6i_rtc_dev *chip = dev_get_drvdata(dev);
+ unsigned long flags;
u32 alrm_st;
u32 alrm_en;

+ spin_lock_irqsave(&chip->lock, flags);
alrm_en = readl(chip->base + SUN6I_ALRM_IRQ_EN);
alrm_st = readl(chip->base + SUN6I_ALRM_IRQ_STA);
+ spin_unlock_irqrestore(&chip->lock, flags);
+
wkalrm->enabled = !!(alrm_en & SUN6I_ALRM_EN_CNT_EN);
wkalrm->pending = !!(alrm_st & SUN6I_ALRM_EN_CNT_EN);
rtc_time_to_tm(chip->alarm, &wkalrm->time);
@@ -356,6 +368,7 @@ static int sun6i_rtc_probe(struct platfo
chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
if (!chip)
return -ENOMEM;
+ spin_lock_init(&chip->lock);

platform_set_drvdata(pdev, chip);
chip->dev = &pdev->dev;