On Fri, Jan 20, 2017 at 11:56 PM, Maxime Ripard
<maxime.ripard@xxxxxxxxxxxxxxxxxx> wrote:
> Some registers have a read-modify-write access pattern that are not atomic.
>
> Add some locking to prevent from concurrent accesses.
>
> Signed-off-by: Maxime Ripard <maxime.ripard@xxxxxxxxxxxxxxxxxx>
Acked-by: Chen-Yu Tsai <wens@xxxxxxxx>
Though I think it would be better to add locking first, then add
clock support, if the original code already had issues?
> ---
> drivers/rtc/rtc-sun6i.c | 20 ++++++++++++++++++--
> 1 file changed, 18 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/rtc/rtc-sun6i.c b/drivers/rtc/rtc-sun6i.c
> index 408dd512a6ac..872d18609183 100644
> --- a/drivers/rtc/rtc-sun6i.c
> +++ b/drivers/rtc/rtc-sun6i.c
> @@ -125,6 +125,8 @@ struct sun6i_rtc_dev {
> struct clk_hw hw;
> struct clk_hw *int_osc;
> struct clk *losc;
> +
> + spinlock_t lock;
> };
>
> static struct sun6i_rtc_dev *sun6i_rtc;
> @@ -155,16 +157,19 @@ static u8 sun6i_rtc_osc_get_parent(struct clk_hw *hw)
> static int sun6i_rtc_osc_set_parent(struct clk_hw *hw, u8 index)
> {
> struct sun6i_rtc_dev *rtc = container_of(hw, struct sun6i_rtc_dev, hw);
> + unsigned long flags;
> u32 val;
>
> if (index > 1)
> return -EINVAL;
>
> + spin_lock_irqsave(&rtc->lock, flags);
> val = readl(rtc->base + SUN6I_LOSC_CTRL);
> val &= ~SUN6I_LOSC_CTRL_EXT_OSC;
> val |= SUN6I_LOSC_CTRL_KEY;
> val |= index ? SUN6I_LOSC_CTRL_EXT_OSC : 0;
> writel(val, rtc->base + SUN6I_LOSC_CTRL);
> + spin_unlock_irqrestore(&rtc->lock, flags);
>
> return 0;
> }
> @@ -187,6 +192,7 @@ static void __init sun6i_rtc_clk_init(struct device_node *node)
> rtc = kzalloc(sizeof(*rtc), GFP_KERNEL);
> if (!rtc)
> pr_crit("Can't allocate RTC structure\n");
> + spin_lock_init(&rtc->lock);
>
> rtc->base = of_io_request_and_map(node, 0, of_node_full_name(node));
> if (!rtc->base) {
> @@ -246,8 +252,10 @@ CLK_OF_DECLARE_DRIVER(sun6i_rtc_clk, "allwinner,sun6i-a31-rtc",
> 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) {
> @@ -256,10 +264,11 @@ 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)
> @@ -267,6 +276,7 @@ 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;
> @@ -277,9 +287,11 @@ 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)
> @@ -318,11 +330,15 @@ 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);
> --
> git-series 0.8.11
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
