rtc: brcmstb-waketimer: support level alarm_irq

[ Upstream commit e005a9b35b464be5b2e0194f717e90e7e496785d ]

Some devices (e.g. BCM72112) use an alarm_irq interrupt that is
connected to a level interrupt controller rather than an edge
interrupt controller. In this case, the interrupt cannot be left
enabled by the irq handler while preserving the hardware wake-up
signal on wake capable devices or an interrupt storm will occur.

The alarm_expired flag is introduced to allow the disabling of
the interrupt when an alarm expires and to support balancing the
calls to disable_irq() and enable_irq() in accordance with the
existing design.

Fixes: 24304a87158a ("rtc: brcmstb-waketimer: allow use as non-wake alarm")
Signed-off-by: Doug Berger <opendmb@gmail.com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Link: https://lore.kernel.org/r/20230830224747.1663044-1-opendmb@gmail.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/rtc/rtc-brcmstb-waketimer.c b/drivers/rtc/rtc-brcmstb-waketimer.c
index 3cdc015..1a65a4e 100644 (file)
--- a/drivers/rtc/rtc-brcmstb-waketimer.c
+++ b/drivers/rtc/rtc-brcmstb-waketimer.c
@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0-only
 /*
- * Copyright © 2014-2017 Broadcom
+ * Copyright © 2014-2023 Broadcom
  */
 
 #define pr_fmt(fmt)    KBUILD_MODNAME ": " fmt
@@ -34,6 +34,7 @@ struct brcmstb_waketmr {
        u32 rate;
        unsigned long rtc_alarm;
        bool alarm_en;
+       bool alarm_expired;
 };
 
 #define BRCMSTB_WKTMR_EVENT            0x00
@@ -64,6 +65,11 @@ static inline void brcmstb_waketmr_clear_alarm(struct brcmstb_waketmr *timer)
        writel_relaxed(reg - 1, timer->base + BRCMSTB_WKTMR_ALARM);
        writel_relaxed(WKTMR_ALARM_EVENT, timer->base + BRCMSTB_WKTMR_EVENT);
        (void)readl_relaxed(timer->base + BRCMSTB_WKTMR_EVENT);
+       if (timer->alarm_expired) {
+               timer->alarm_expired = false;
+               /* maintain call balance */
+               enable_irq(timer->alarm_irq);
+       }
 }
 
 static void brcmstb_waketmr_set_alarm(struct brcmstb_waketmr *timer,
@@ -105,10 +111,17 @@ static irqreturn_t brcmstb_alarm_irq(int irq, void *data)
                return IRQ_HANDLED;
 
        if (timer->alarm_en) {
-               if (!device_may_wakeup(timer->dev))
+               if (device_may_wakeup(timer->dev)) {
+                       disable_irq_nosync(irq);
+                       timer->alarm_expired = true;
+               } else {
                        writel_relaxed(WKTMR_ALARM_EVENT,
                                       timer->base + BRCMSTB_WKTMR_EVENT);
+               }
                rtc_update_irq(timer->rtc, 1, RTC_IRQF | RTC_AF);
+       } else {
+               writel_relaxed(WKTMR_ALARM_EVENT,
+                              timer->base + BRCMSTB_WKTMR_EVENT);
        }
 
        return IRQ_HANDLED;
@@ -221,8 +234,14 @@ static int brcmstb_waketmr_alarm_enable(struct device *dev,
                    !brcmstb_waketmr_is_pending(timer))
                        return -EINVAL;
                timer->alarm_en = true;
-               if (timer->alarm_irq)
+               if (timer->alarm_irq) {
+                       if (timer->alarm_expired) {
+                               timer->alarm_expired = false;
+                               /* maintain call balance */
+                               enable_irq(timer->alarm_irq);
+                       }
                        enable_irq(timer->alarm_irq);
+               }
        } else if (!enabled && timer->alarm_en) {
                if (timer->alarm_irq)
                        disable_irq(timer->alarm_irq);
@@ -352,6 +371,17 @@ static int brcmstb_waketmr_suspend(struct device *dev)
        return brcmstb_waketmr_prepare_suspend(timer);
 }
 
+static int brcmstb_waketmr_suspend_noirq(struct device *dev)
+{
+       struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
+
+       /* Catch any alarms occurring prior to noirq */
+       if (timer->alarm_expired && device_may_wakeup(dev))
+               return -EBUSY;
+
+       return 0;
+}
+
 static int brcmstb_waketmr_resume(struct device *dev)
 {
        struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
@@ -368,10 +398,17 @@ static int brcmstb_waketmr_resume(struct device *dev)
 
        return ret;
 }
+#else
+#define brcmstb_waketmr_suspend                NULL
+#define brcmstb_waketmr_suspend_noirq  NULL
+#define brcmstb_waketmr_resume         NULL
 #endif /* CONFIG_PM_SLEEP */
 
-static SIMPLE_DEV_PM_OPS(brcmstb_waketmr_pm_ops,
-                        brcmstb_waketmr_suspend, brcmstb_waketmr_resume);
+static const struct dev_pm_ops brcmstb_waketmr_pm_ops = {
+       .suspend        = brcmstb_waketmr_suspend,
+       .suspend_noirq  = brcmstb_waketmr_suspend_noirq,
+       .resume         = brcmstb_waketmr_resume,
+};
 
 static const __maybe_unused struct of_device_id brcmstb_waketmr_of_match[] = {
        { .compatible = "brcm,brcmstb-waketimer" },