rtc: sun6i: Add some locking

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

Add some locking to prevent from concurrent accesses.

Cc: stable@vger.kernel.org
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>

1 files changed, 15 insertions, 2 deletions

diff --git a/drivers/rtc/rtc-sun6i.c b/drivers/rtc/rtc-sun6i.c
index a6136cb99851..72086f0c0782 100644
--- 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(int irq, void *id)
 
                 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, struct sun6i_rtc_dev *chip)
         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, struct sun6i_rtc_dev *chip)
                        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 device *dev, struct rtc_time *rtc_tm)
 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 platform_device *pdev)
         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;