Merge branch 'irq-pm'

* irq-pm:
  genirq / PM: describe IRQF_COND_SUSPEND
  tty: serial: atmel: rework interrupt and wakeup handling
  watchdog: at91sam9: request the irq with IRQF_NO_SUSPEND
  clk: at91: implement suspend/resume for the PMC irqchip
  rtc: at91rm9200: rework wakeup and interrupt handling
  rtc: at91sam9: rework wakeup and interrupt handling
  PM / wakeup: export pm_system_wakeup symbol
  genirq / PM: Add flag for shared NO_SUSPEND interrupt lines
  genirq / PM: better describe IRQF_NO_SUSPEND semantics

Documentation/power/suspend-and-interrupts.txt

@@ -40,8 +40,10 @@ but also to IPIs and to some other special-purpose interrupts.
 
 The IRQF_NO_SUSPEND flag is used to indicate that to the IRQ subsystem when
 requesting a special-purpose interrupt.  It causes suspend_device_irqs() to
-leave the corresponding IRQ enabled so as to allow the interrupt to work all
-the time as expected.
+leave the corresponding IRQ enabled so as to allow the interrupt to work as
+expected during the suspend-resume cycle, but does not guarantee that the
+interrupt will wake the system from a suspended state -- for such cases it is
+necessary to use enable_irq_wake().
 
 Note that the IRQF_NO_SUSPEND flag affects the entire IRQ and not just one
 user of it.  Thus, if the IRQ is shared, all of the interrupt handlers installed
@@ -110,8 +112,9 @@ any special interrupt handling logic for it to work.
 IRQF_NO_SUSPEND and enable_irq_wake()
 -------------------------------------
 
-There are no valid reasons to use both enable_irq_wake() and the IRQF_NO_SUSPEND
-flag on the same IRQ.
+There are very few valid reasons to use both enable_irq_wake() and the
+IRQF_NO_SUSPEND flag on the same IRQ, and it is never valid to use both for the
+same device.
 
 First of all, if the IRQ is not shared, the rules for handling IRQF_NO_SUSPEND
 interrupts (interrupt handlers are invoked after suspend_device_irqs()) are
@@ -120,4 +123,13 @@ handlers are not invoked after suspend_device_irqs()).
 
 Second, both enable_irq_wake() and IRQF_NO_SUSPEND apply to entire IRQs and not
 to individual interrupt handlers, so sharing an IRQ between a system wakeup
-interrupt source and an IRQF_NO_SUSPEND interrupt source does not make sense.
+interrupt source and an IRQF_NO_SUSPEND interrupt source does not generally
+make sense.
+
+In rare cases an IRQ can be shared between a wakeup device driver and an
+IRQF_NO_SUSPEND user. In order for this to be safe, the wakeup device driver
+must be able to discern spurious IRQs from genuine wakeup events (signalling
+the latter to the core with pm_system_wakeup()), must use enable_irq_wake() to
+ensure that the IRQ will function as a wakeup source, and must request the IRQ
+with IRQF_COND_SUSPEND to tell the core that it meets these requirements. If
+these requirements are not met, it is not valid to use IRQF_COND_SUSPEND.

drivers/base/power/wakeup.c

@@ -730,6 +730,7 @@ void pm_system_wakeup(void)
 	pm_abort_suspend = true;
 	freeze_wake();
 }
+EXPORT_SYMBOL_GPL(pm_system_wakeup);
 
 void pm_wakeup_clear(void)
 {

drivers/clk/at91/pmc.c

@@ -89,12 +89,29 @@ static int pmc_irq_set_type(struct irq_data *d, unsigned type)
 	return 0;
 }
 
+static void pmc_irq_suspend(struct irq_data *d)
+{
+	struct at91_pmc *pmc = irq_data_get_irq_chip_data(d);
+
+	pmc->imr = pmc_read(pmc, AT91_PMC_IMR);
+	pmc_write(pmc, AT91_PMC_IDR, pmc->imr);
+}
+
+static void pmc_irq_resume(struct irq_data *d)
+{
+	struct at91_pmc *pmc = irq_data_get_irq_chip_data(d);
+
+	pmc_write(pmc, AT91_PMC_IER, pmc->imr);
+}
+
 static struct irq_chip pmc_irq = {
 	.name = "PMC",
 	.irq_disable = pmc_irq_mask,
 	.irq_mask = pmc_irq_mask,
 	.irq_unmask = pmc_irq_unmask,
 	.irq_set_type = pmc_irq_set_type,
+	.irq_suspend = pmc_irq_suspend,
+	.irq_resume = pmc_irq_resume,
 };
 
 static struct lock_class_key pmc_lock_class;
@@ -224,7 +241,8 @@ static struct at91_pmc *__init at91_pmc_init(struct device_node *np,
 		goto out_free_pmc;
 
 	pmc_write(pmc, AT91_PMC_IDR, 0xffffffff);
-	if (request_irq(pmc->virq, pmc_irq_handler, IRQF_SHARED, "pmc", pmc))
+	if (request_irq(pmc->virq, pmc_irq_handler,
+			IRQF_SHARED | IRQF_COND_SUSPEND, "pmc", pmc))
 		goto out_remove_irqdomain;
 
 	return pmc;

drivers/clk/at91/pmc.h

@@ -33,6 +33,7 @@ struct at91_pmc {
 	spinlock_t lock;
 	const struct at91_pmc_caps *caps;
 	struct irq_domain *irqdomain;
+	u32 imr;
 };
 
 static inline void pmc_lock(struct at91_pmc *pmc)

drivers/rtc/rtc-at91rm9200.c

@@ -31,6 +31,7 @@
 #include <linux/io.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
+#include <linux/suspend.h>
 #include <linux/uaccess.h>
 
 #include "rtc-at91rm9200.h"
@@ -54,6 +55,10 @@ static void __iomem *at91_rtc_regs;
 static int irq;
 static DEFINE_SPINLOCK(at91_rtc_lock);
 static u32 at91_rtc_shadow_imr;
+static bool suspended;
+static DEFINE_SPINLOCK(suspended_lock);
+static unsigned long cached_events;
+static u32 at91_rtc_imr;
 
 static void at91_rtc_write_ier(u32 mask)
 {
@@ -290,7 +295,9 @@ static irqreturn_t at91_rtc_interrupt(int irq, void *dev_id)
 	struct rtc_device *rtc = platform_get_drvdata(pdev);
 	unsigned int rtsr;
 	unsigned long events = 0;
+	int ret = IRQ_NONE;
 
+	spin_lock(&suspended_lock);
 	rtsr = at91_rtc_read(AT91_RTC_SR) & at91_rtc_read_imr();
 	if (rtsr) {		/* this interrupt is shared!  Is it ours? */
 		if (rtsr & AT91_RTC_ALARM)
@@ -304,14 +311,22 @@ static irqreturn_t at91_rtc_interrupt(int irq, void *dev_id)
 
 		at91_rtc_write(AT91_RTC_SCCR, rtsr);	/* clear status reg */
 
-		rtc_update_irq(rtc, 1, events);
+		if (!suspended) {
+			rtc_update_irq(rtc, 1, events);
 
-		dev_dbg(&pdev->dev, "%s(): num=%ld, events=0x%02lx\n", __func__,
-			events >> 8, events & 0x000000FF);
+			dev_dbg(&pdev->dev, "%s(): num=%ld, events=0x%02lx\n",
+				__func__, events >> 8, events & 0x000000FF);
+		} else {
+			cached_events |= events;
+			at91_rtc_write_idr(at91_rtc_imr);
+			pm_system_wakeup();
+		}
 
-		return IRQ_HANDLED;
+		ret = IRQ_HANDLED;
 	}
-	return IRQ_NONE;		/* not handled */
+	spin_lock(&suspended_lock);
+
+	return ret;
 }
 
 static const struct at91_rtc_config at91rm9200_config = {
@@ -401,8 +416,8 @@ static int __init at91_rtc_probe(struct platform_device *pdev)
 					AT91_RTC_CALEV);
 
 	ret = devm_request_irq(&pdev->dev, irq, at91_rtc_interrupt,
-				IRQF_SHARED,
-				"at91_rtc", pdev);
+			       IRQF_SHARED | IRQF_COND_SUSPEND,
+			       "at91_rtc", pdev);
 	if (ret) {
 		dev_err(&pdev->dev, "IRQ %d already in use.\n", irq);
 		return ret;
@@ -454,8 +469,6 @@ static void at91_rtc_shutdown(struct platform_device *pdev)
 
 /* AT91RM9200 RTC Power management control */
 
-static u32 at91_rtc_imr;
-
 static int at91_rtc_suspend(struct device *dev)
 {
 	/* this IRQ is shared with DBGU and other hardware which isn't
@@ -464,21 +477,42 @@ static int at91_rtc_suspend(struct device *dev)
 	at91_rtc_imr = at91_rtc_read_imr()
 			& (AT91_RTC_ALARM|AT91_RTC_SECEV);
 	if (at91_rtc_imr) {
-		if (device_may_wakeup(dev))
+		if (device_may_wakeup(dev)) {
+			unsigned long flags;
+
 			enable_irq_wake(irq);
-		else
+
+			spin_lock_irqsave(&suspended_lock, flags);
+			suspended = true;
+			spin_unlock_irqrestore(&suspended_lock, flags);
+		} else {
 			at91_rtc_write_idr(at91_rtc_imr);
+		}
 	}
 	return 0;
 }
 
 static int at91_rtc_resume(struct device *dev)
 {
+	struct rtc_device *rtc = dev_get_drvdata(dev);
+
 	if (at91_rtc_imr) {
-		if (device_may_wakeup(dev))
+		if (device_may_wakeup(dev)) {
+			unsigned long flags;
+
+			spin_lock_irqsave(&suspended_lock, flags);
+
+			if (cached_events) {
+				rtc_update_irq(rtc, 1, cached_events);
+				cached_events = 0;
+			}
+
+			suspended = false;
+			spin_unlock_irqrestore(&suspended_lock, flags);
+
 			disable_irq_wake(irq);
-		else
-			at91_rtc_write_ier(at91_rtc_imr);
+		}
+		at91_rtc_write_ier(at91_rtc_imr);
 	}
 	return 0;
 }

drivers/rtc/rtc-at91sam9.c

@@ -23,6 +23,7 @@
 #include <linux/io.h>
 #include <linux/mfd/syscon.h>
 #include <linux/regmap.h>
+#include <linux/suspend.h>
 #include <linux/clk.h>
 
 /*
@@ -77,6 +78,9 @@ struct sam9_rtc {
 	unsigned int		gpbr_offset;
 	int 			irq;
 	struct clk		*sclk;
+	bool			suspended;
+	unsigned long		events;
+	spinlock_t		lock;
 };
 
 #define rtt_readl(rtc, field) \
@@ -271,14 +275,9 @@ static int at91_rtc_proc(struct device *dev, struct seq_file *seq)
 	return 0;
 }
 
-/*
- * IRQ handler for the RTC
- */
-static irqreturn_t at91_rtc_interrupt(int irq, void *_rtc)
+static irqreturn_t at91_rtc_cache_events(struct sam9_rtc *rtc)
 {
-	struct sam9_rtc *rtc = _rtc;
 	u32 sr, mr;
-	unsigned long events = 0;
 
 	/* Shared interrupt may be for another device.  Note: reading
 	 * SR clears it, so we must only read it in this irq handler!
@@ -290,18 +289,54 @@ static irqreturn_t at91_rtc_interrupt(int irq, void *_rtc)
 
 	/* alarm status */
 	if (sr & AT91_RTT_ALMS)
-		events |= (RTC_AF | RTC_IRQF);
+		rtc->events |= (RTC_AF | RTC_IRQF);
 
 	/* timer update/increment */
 	if (sr & AT91_RTT_RTTINC)
-		events |= (RTC_UF | RTC_IRQF);
+		rtc->events |= (RTC_UF | RTC_IRQF);
+
+	return IRQ_HANDLED;
+}
+
+static void at91_rtc_flush_events(struct sam9_rtc *rtc)
+{
+	if (!rtc->events)
+		return;
 
-	rtc_update_irq(rtc->rtcdev, 1, events);
+	rtc_update_irq(rtc->rtcdev, 1, rtc->events);
+	rtc->events = 0;
 
 	pr_debug("%s: num=%ld, events=0x%02lx\n", __func__,
-		events >> 8, events & 0x000000FF);
+		rtc->events >> 8, rtc->events & 0x000000FF);
+}
 
-	return IRQ_HANDLED;
+/*
+ * IRQ handler for the RTC
+ */
+static irqreturn_t at91_rtc_interrupt(int irq, void *_rtc)
+{
+	struct sam9_rtc *rtc = _rtc;
+	int ret;
+
+	spin_lock(&rtc->lock);
+
+	ret = at91_rtc_cache_events(rtc);
+
+	/* We're called in suspended state */
+	if (rtc->suspended) {
+		/* Mask irqs coming from this peripheral */
+		rtt_writel(rtc, MR,
+			   rtt_readl(rtc, MR) &
+			   ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN));
+		/* Trigger a system wakeup */
+		pm_system_wakeup();
+	} else {
+		at91_rtc_flush_events(rtc);
+	}
+
+	spin_unlock(&rtc->lock);
+
+	return ret;
 }
 
 static const struct rtc_class_ops at91_rtc_ops = {
@@ -421,7 +456,8 @@ static int at91_rtc_probe(struct platform_device *pdev)
 
 	/* register irq handler after we know what name we'll use */
 	ret = devm_request_irq(&pdev->dev, rtc->irq, at91_rtc_interrupt,
-				IRQF_SHARED, dev_name(&rtc->rtcdev->dev), rtc);
+			       IRQF_SHARED | IRQF_COND_SUSPEND,
+			       dev_name(&rtc->rtcdev->dev), rtc);
 	if (ret) {
 		dev_dbg(&pdev->dev, "can't share IRQ %d?\n", rtc->irq);
 		return ret;
@@ -482,7 +518,12 @@ static int at91_rtc_suspend(struct device *dev)
 	rtc->imr = mr & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN);
 	if (rtc->imr) {
 		if (device_may_wakeup(dev) && (mr & AT91_RTT_ALMIEN)) {
+			unsigned long flags;
+
 			enable_irq_wake(rtc->irq);
+			spin_lock_irqsave(&rtc->lock, flags);
+			rtc->suspended = true;
+			spin_unlock_irqrestore(&rtc->lock, flags);
 			/* don't let RTTINC cause wakeups */
 			if (mr & AT91_RTT_RTTINCIEN)
 				rtt_writel(rtc, MR, mr & ~AT91_RTT_RTTINCIEN);
@@ -499,10 +540,18 @@ static int at91_rtc_resume(struct device *dev)
 	u32		mr;
 
 	if (rtc->imr) {
+		unsigned long flags;
+
 		if (device_may_wakeup(dev))
 			disable_irq_wake(rtc->irq);
 		mr = rtt_readl(rtc, MR);
 		rtt_writel(rtc, MR, mr | rtc->imr);
+
+		spin_lock_irqsave(&rtc->lock, flags);
+		rtc->suspended = false;
+		at91_rtc_cache_events(rtc);
+		at91_rtc_flush_events(rtc);
+		spin_unlock_irqrestore(&rtc->lock, flags);
 	}
 
 	return 0;