Merge branch 'pm-genirq' into acpi-pm

Documentation/power/suspend-and-interrupts.txt

@@ -0,0 +1,123 @@
+System Suspend and Device Interrupts
+
+Copyright (C) 2014 Intel Corp.
+Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
+
+
+Suspending and Resuming Device IRQs
+-----------------------------------
+
+Device interrupt request lines (IRQs) are generally disabled during system
+suspend after the "late" phase of suspending devices (that is, after all of the
+->prepare, ->suspend and ->suspend_late callbacks have been executed for all
+devices).  That is done by suspend_device_irqs().
+
+The rationale for doing so is that after the "late" phase of device suspend
+there is no legitimate reason why any interrupts from suspended devices should
+trigger and if any devices have not been suspended properly yet, it is better to
+block interrupts from them anyway.  Also, in the past we had problems with
+interrupt handlers for shared IRQs that device drivers implementing them were
+not prepared for interrupts triggering after their devices had been suspended.
+In some cases they would attempt to access, for example, memory address spaces
+of suspended devices and cause unpredictable behavior to ensue as a result.
+Unfortunately, such problems are very difficult to debug and the introduction
+of suspend_device_irqs(), along with the "noirq" phase of device suspend and
+resume, was the only practical way to mitigate them.
+
+Device IRQs are re-enabled during system resume, right before the "early" phase
+of resuming devices (that is, before starting to execute ->resume_early
+callbacks for devices).  The function doing that is resume_device_irqs().
+
+
+The IRQF_NO_SUSPEND Flag
+------------------------
+
+There are interrupts that can legitimately trigger during the entire system
+suspend-resume cycle, including the "noirq" phases of suspending and resuming
+devices as well as during the time when nonboot CPUs are taken offline and
+brought back online.  That applies to timer interrupts in the first place,
+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.
+
+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
+for it will be executed as usual after suspend_device_irqs(), even if the
+IRQF_NO_SUSPEND flag was not passed to request_irq() (or equivalent) by some of
+the IRQ's users.  For this reason, using IRQF_NO_SUSPEND and IRQF_SHARED at the
+same time should be avoided.
+
+
+System Wakeup Interrupts, enable_irq_wake() and disable_irq_wake()
+------------------------------------------------------------------
+
+System wakeup interrupts generally need to be configured to wake up the system
+from sleep states, especially if they are used for different purposes (e.g. as
+I/O interrupts) in the working state.
+
+That may involve turning on a special signal handling logic within the platform
+(such as an SoC) so that signals from a given line are routed in a different way
+during system sleep so as to trigger a system wakeup when needed.  For example,
+the platform may include a dedicated interrupt controller used specifically for
+handling system wakeup events.  Then, if a given interrupt line is supposed to
+wake up the system from sleep sates, the corresponding input of that interrupt
+controller needs to be enabled to receive signals from the line in question.
+After wakeup, it generally is better to disable that input to prevent the
+dedicated controller from triggering interrupts unnecessarily.
+
+The IRQ subsystem provides two helper functions to be used by device drivers for
+those purposes.  Namely, enable_irq_wake() turns on the platform's logic for
+handling the given IRQ as a system wakeup interrupt line and disable_irq_wake()
+turns that logic off.
+
+Calling enable_irq_wake() causes suspend_device_irqs() to treat the given IRQ
+in a special way.  Namely, the IRQ remains enabled, by on the first interrupt
+it will be disabled, marked as pending and "suspended" so that it will be
+re-enabled by resume_device_irqs() during the subsequent system resume.  Also
+the PM core is notified about the event which casues the system suspend in
+progress to be aborted (that doesn't have to happen immediately, but at one
+of the points where the suspend thread looks for pending wakeup events).
+
+This way every interrupt from a wakeup interrupt source will either cause the
+system suspend currently in progress to be aborted or wake up the system if
+already suspended.  However, after suspend_device_irqs() interrupt handlers are
+not executed for system wakeup IRQs.  They are only executed for IRQF_NO_SUSPEND
+IRQs at that time, but those IRQs should not be configured for system wakeup
+using enable_irq_wake().
+
+
+Interrupts and Suspend-to-Idle
+------------------------------
+
+Suspend-to-idle (also known as the "freeze" sleep state) is a relatively new
+system sleep state that works by idling all of the processors and waiting for
+interrupts right after the "noirq" phase of suspending devices.
+
+Of course, this means that all of the interrupts with the IRQF_NO_SUSPEND flag
+set will bring CPUs out of idle while in that state, but they will not cause the
+IRQ subsystem to trigger a system wakeup.
+
+System wakeup interrupts, in turn, will trigger wakeup from suspend-to-idle in
+analogy with what they do in the full system suspend case.  The only difference
+is that the wakeup from suspend-to-idle is signaled using the usual working
+state interrupt delivery mechanisms and doesn't require the platform to use
+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.
+
+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
+directly at odds with the rules for handling system wakeup interrupts (interrupt
+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.

arch/x86/kernel/apic/io_apic.c

@@ -2623,6 +2623,7 @@ static struct irq_chip ioapic_chip __read_mostly = {
 	.irq_eoi		= ack_apic_level,
 	.irq_set_affinity	= native_ioapic_set_affinity,
 	.irq_retrigger		= ioapic_retrigger_irq,
+	.flags			= IRQCHIP_SKIP_SET_WAKE,
 };
 
 static inline void init_IO_APIC_traps(void)
@@ -3173,6 +3174,7 @@ static struct irq_chip msi_chip = {
 	.irq_ack		= ack_apic_edge,
 	.irq_set_affinity	= msi_set_affinity,
 	.irq_retrigger		= ioapic_retrigger_irq,
+	.flags			= IRQCHIP_SKIP_SET_WAKE,
 };
 
 int setup_msi_irq(struct pci_dev *dev, struct msi_desc *msidesc,
@@ -3271,6 +3273,7 @@ static struct irq_chip dmar_msi_type = {
 	.irq_ack		= ack_apic_edge,
 	.irq_set_affinity	= dmar_msi_set_affinity,
 	.irq_retrigger		= ioapic_retrigger_irq,
+	.flags			= IRQCHIP_SKIP_SET_WAKE,
 };
 
 int arch_setup_dmar_msi(unsigned int irq)
@@ -3321,6 +3324,7 @@ static struct irq_chip hpet_msi_type = {
 	.irq_ack = ack_apic_edge,
 	.irq_set_affinity = hpet_msi_set_affinity,
 	.irq_retrigger = ioapic_retrigger_irq,
+	.flags = IRQCHIP_SKIP_SET_WAKE,
 };
 
 int default_setup_hpet_msi(unsigned int irq, unsigned int id)
@@ -3384,6 +3388,7 @@ static struct irq_chip ht_irq_chip = {
 	.irq_ack		= ack_apic_edge,
 	.irq_set_affinity	= ht_set_affinity,
 	.irq_retrigger		= ioapic_retrigger_irq,
+	.flags			= IRQCHIP_SKIP_SET_WAKE,
 };
 
 int arch_setup_ht_irq(unsigned int irq, struct pci_dev *dev)

drivers/base/power/wakeup.c

@@ -24,6 +24,9 @@
  */
 bool events_check_enabled __read_mostly;
 
+/* If set and the system is suspending, terminate the suspend. */
+static bool pm_abort_suspend __read_mostly;
+
 /*
  * Combined counters of registered wakeup events and wakeup events in progress.
  * They need to be modified together atomically, so it's better to use one
@@ -719,7 +722,18 @@ bool pm_wakeup_pending(void)
 		pm_print_active_wakeup_sources();
 	}
 
-	return ret;
+	return ret || pm_abort_suspend;
+}
+
+void pm_system_wakeup(void)
+{
+	pm_abort_suspend = true;
+	freeze_wake();
+}
+
+void pm_wakeup_clear(void)
+{
+	pm_abort_suspend = false;
 }
 
 /**

drivers/base/syscore.c

@@ -9,7 +9,7 @@
 #include <linux/syscore_ops.h>
 #include <linux/mutex.h>
 #include <linux/module.h>
-#include <linux/interrupt.h>
+#include <linux/suspend.h>
 #include <trace/events/power.h>
 
 static LIST_HEAD(syscore_ops_list);
@@ -54,9 +54,8 @@ int syscore_suspend(void)
 	pr_debug("Checking wakeup interrupts\n");
 
 	/* Return error code if there are any wakeup interrupts pending. */
-	ret = check_wakeup_irqs();
-	if (ret)
-		return ret;
+	if (pm_wakeup_pending())
+		return -EBUSY;
 
 	WARN_ONCE(!irqs_disabled(),
 		"Interrupts enabled before system core suspend.\n");

drivers/pci/pcie/pme.c

@@ -41,11 +41,17 @@ static int __init pcie_pme_setup(char *str)
 }
 __setup("pcie_pme=", pcie_pme_setup);
 
+enum pme_suspend_level {
+	PME_SUSPEND_NONE = 0,
+	PME_SUSPEND_WAKEUP,
+	PME_SUSPEND_NOIRQ,
+};
+
 struct pcie_pme_service_data {
 	spinlock_t lock;
 	struct pcie_device *srv;
 	struct work_struct work;
-	bool noirq; /* Don't enable the PME interrupt used by this service. */
+	enum pme_suspend_level suspend_level;
 };
 
 /**
@@ -223,7 +229,7 @@ static void pcie_pme_work_fn(struct work_struct *work)
 	spin_lock_irq(&data->lock);
 
 	for (;;) {
-		if (data->noirq)
+		if (data->suspend_level != PME_SUSPEND_NONE)
 			break;
 
 		pcie_capability_read_dword(port, PCI_EXP_RTSTA, &rtsta);
@@ -250,7 +256,7 @@ static void pcie_pme_work_fn(struct work_struct *work)
 		spin_lock_irq(&data->lock);
 	}
 
-	if (!data->noirq)
+	if (data->suspend_level == PME_SUSPEND_NONE)
 		pcie_pme_interrupt_enable(port, true);
 
 	spin_unlock_irq(&data->lock);
@@ -367,6 +373,21 @@ static int pcie_pme_probe(struct pcie_device *srv)
 	return ret;
 }
 
+static bool pcie_pme_check_wakeup(struct pci_bus *bus)
+{
+	struct pci_dev *dev;
+
+	if (!bus)
+		return false;
+
+	list_for_each_entry(dev, &bus->devices, bus_list)
+		if (device_may_wakeup(&dev->dev)
+		    || pcie_pme_check_wakeup(dev->subordinate))
+			return true;
+
+	return false;
+}
+
 /**
  * pcie_pme_suspend - Suspend PCIe PME service device.
  * @srv: PCIe service device to suspend.
@@ -375,11 +396,26 @@ static int pcie_pme_suspend(struct pcie_device *srv)
 {
 	struct pcie_pme_service_data *data = get_service_data(srv);
 	struct pci_dev *port = srv->port;
+	bool wakeup;
 
+	if (device_may_wakeup(&port->dev)) {
+		wakeup = true;
+	} else {
+		down_read(&pci_bus_sem);
+		wakeup = pcie_pme_check_wakeup(port->subordinate);
+		up_read(&pci_bus_sem);
+	}
 	spin_lock_irq(&data->lock);
-	pcie_pme_interrupt_enable(port, false);
-	pcie_clear_root_pme_status(port);
-	data->noirq = true;
+	if (wakeup) {
+		enable_irq_wake(srv->irq);
+		data->suspend_level = PME_SUSPEND_WAKEUP;
+	} else {
+		struct pci_dev *port = srv->port;
+
+		pcie_pme_interrupt_enable(port, false);
+		pcie_clear_root_pme_status(port);
+		data->suspend_level = PME_SUSPEND_NOIRQ;
+	}
 	spin_unlock_irq(&data->lock);
 
 	synchronize_irq(srv->irq);
@@ -394,12 +430,17 @@ static int pcie_pme_suspend(struct pcie_device *srv)
 static int pcie_pme_resume(struct pcie_device *srv)
 {
 	struct pcie_pme_service_data *data = get_service_data(srv);
-	struct pci_dev *port = srv->port;
 
 	spin_lock_irq(&data->lock);
-	data->noirq = false;
-	pcie_clear_root_pme_status(port);
-	pcie_pme_interrupt_enable(port, true);
+	if (data->suspend_level == PME_SUSPEND_NOIRQ) {
+		struct pci_dev *port = srv->port;
+
+		pcie_clear_root_pme_status(port);
+		pcie_pme_interrupt_enable(port, true);
+	} else {
+		disable_irq_wake(srv->irq);
+	}
+	data->suspend_level = PME_SUSPEND_NONE;
 	spin_unlock_irq(&data->lock);
 
 	return 0;

include/linux/interrupt.h

@@ -193,11 +193,6 @@ extern void irq_wake_thread(unsigned int irq, void *dev_id);
 /* The following three functions are for the core kernel use only. */
 extern void suspend_device_irqs(void);
 extern void resume_device_irqs(void);
-#ifdef CONFIG_PM_SLEEP
-extern int check_wakeup_irqs(void);
-#else
-static inline int check_wakeup_irqs(void) { return 0; }
-#endif
 
 /**
  * struct irq_affinity_notify - context for notification of IRQ affinity changes

include/linux/irq.h

@@ -173,6 +173,7 @@ struct irq_data {
  * IRQD_IRQ_DISABLED		- Disabled state of the interrupt
  * IRQD_IRQ_MASKED		- Masked state of the interrupt
  * IRQD_IRQ_INPROGRESS		- In progress state of the interrupt
+ * IRQD_WAKEUP_ARMED		- Wakeup mode armed
  */
 enum {
 	IRQD_TRIGGER_MASK		= 0xf,
@@ -186,6 +187,7 @@ enum {
 	IRQD_IRQ_DISABLED		= (1 << 16),
 	IRQD_IRQ_MASKED			= (1 << 17),
 	IRQD_IRQ_INPROGRESS		= (1 << 18),
+	IRQD_WAKEUP_ARMED		= (1 << 19),
 };
 
 static inline bool irqd_is_setaffinity_pending(struct irq_data *d)
@@ -257,6 +259,12 @@ static inline bool irqd_irq_inprogress(struct irq_data *d)
 	return d->state_use_accessors & IRQD_IRQ_INPROGRESS;
 }
 
+static inline bool irqd_is_wakeup_armed(struct irq_data *d)
+{
+	return d->state_use_accessors & IRQD_WAKEUP_ARMED;
+}
+
+
 /*
  * Functions for chained handlers which can be enabled/disabled by the
  * standard disable_irq/enable_irq calls. Must be called with

include/linux/irqdesc.h

@@ -36,6 +36,11 @@ struct irq_desc;
  * @threads_oneshot:	bitfield to handle shared oneshot threads
  * @threads_active:	number of irqaction threads currently running
  * @wait_for_threads:	wait queue for sync_irq to wait for threaded handlers
+ * @nr_actions:		number of installed actions on this descriptor
+ * @no_suspend_depth:	number of irqactions on a irq descriptor with
+ *			IRQF_NO_SUSPEND set
+ * @force_resume_depth:	number of irqactions on a irq descriptor with
+ *			IRQF_FORCE_RESUME set
  * @dir:		/proc/irq/ procfs entry
  * @name:		flow handler name for /proc/interrupts output
  */
@@ -68,6 +73,11 @@ struct irq_desc {
 	unsigned long		threads_oneshot;
 	atomic_t		threads_active;
 	wait_queue_head_t       wait_for_threads;
+#ifdef CONFIG_PM_SLEEP
+	unsigned int		nr_actions;
+	unsigned int		no_suspend_depth;
+	unsigned int		force_resume_depth;
+#endif
 #ifdef CONFIG_PROC_FS
 	struct proc_dir_entry	*dir;
 #endif