[RFC PATCH V2 3/8] genirq: Add runtime power management support for IRQ chips

[Jon Hunter <jonathanh@nvidia.com>]

Some IRQ chips may be located in a power domain outside of the CPU
subsystem and hence will require device specific runtime power management.
In order to support such IRQ chips, add a pointer for a device structure
to the irq_chip structure, and if this pointer is populated by the IRQ
chip driver and the flag CHIP_HAS_RPM is set, then the pm_runtime_get/put
APIs for this chip will be called when an IRQ is requested/freed,
respectively.

Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
---
 include/linux/irq.h    |  4 ++++
 kernel/irq/internals.h | 24 ++++++++++++++++++++++++
 kernel/irq/manage.c    |  7 +++++++
 3 files changed, 35 insertions(+)

diff --git a/include/linux/irq.h b/include/linux/irq.h
index 3c1c96786248..7a61a7f76177 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -307,6 +307,7 @@ static inline irq_hw_number_t irqd_to_hwirq(struct irq_data *d)
 /**
  * struct irq_chip - hardware interrupt chip descriptor
  *
+ * @dev:		pointer to associated device
  * @name:		name for /proc/interrupts
  * @irq_startup:	start up the interrupt (defaults to ->enable if NULL)
  * @irq_shutdown:	shut down the interrupt (defaults to ->disable if NULL)
@@ -344,6 +345,7 @@ static inline irq_hw_number_t irqd_to_hwirq(struct irq_data *d)
  * @flags:		chip specific flags
  */
 struct irq_chip {
+	struct device	*dev;
 	const char	*name;
 	unsigned int	(*irq_startup)(struct irq_data *data);
 	void		(*irq_shutdown)(struct irq_data *data);
@@ -399,6 +401,7 @@ struct irq_chip {
  * IRQCHIP_SKIP_SET_WAKE:	Skip chip.irq_set_wake(), for this irq chip
  * IRQCHIP_ONESHOT_SAFE:	One shot does not require mask/unmask
  * IRQCHIP_EOI_THREADED:	Chip requires eoi() on unmask in threaded mode
+ * IRQCHIP_HAS_PM:		Chip requires runtime power management
  */
 enum {
 	IRQCHIP_SET_TYPE_MASKED		= (1 <<  0),
@@ -408,6 +411,7 @@ enum {
 	IRQCHIP_SKIP_SET_WAKE		= (1 <<  4),
 	IRQCHIP_ONESHOT_SAFE		= (1 <<  5),
 	IRQCHIP_EOI_THREADED		= (1 <<  6),
+	IRQCHIP_HAS_RPM			= (1 <<  7),
 };
 
 #include <linux/irqdesc.h>
diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h
index fcab63c66905..30a2add7cae6 100644
--- a/kernel/irq/internals.h
+++ b/kernel/irq/internals.h
@@ -7,6 +7,7 @@
  */
 #include <linux/irqdesc.h>
 #include <linux/kernel_stat.h>
+#include <linux/pm_runtime.h>
 
 #ifdef CONFIG_SPARSE_IRQ
 # define IRQ_BITMAP_BITS	(NR_IRQS + 8196)
@@ -125,6 +126,29 @@ static inline void chip_bus_sync_unlock(struct irq_desc *desc)
 		desc->irq_data.chip->irq_bus_sync_unlock(&desc->irq_data);
 }
 
+/* Inline functions for support of irq chips that require runtime pm */
+static inline int chip_pm_get(struct irq_desc *desc)
+{
+	int retval = 0;
+
+	if (desc->irq_data.chip->dev &&
+	    desc->irq_data.chip->flags & IRQCHIP_HAS_RPM)
+		retval = pm_runtime_get_sync(desc->irq_data.chip->dev);
+
+	return (retval < 0) ? retval : 0;
+}
+
+static inline int chip_pm_put(struct irq_desc *desc)
+{
+	int retval = 0;
+
+	if (desc->irq_data.chip->dev &&
+	    desc->irq_data.chip->flags & IRQCHIP_HAS_RPM)
+		retval = pm_runtime_put(desc->irq_data.chip->dev);
+
+	return (retval < 0) ? retval : 0;
+}
+
 #define _IRQ_DESC_CHECK		(1 << 0)
 #define _IRQ_DESC_PERCPU	(1 << 1)
 
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 2a429b061171..8a96e4f1e985 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -1116,6 +1116,10 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
 	if (!try_module_get(desc->owner))
 		return -ENODEV;
 
+	ret = chip_pm_get(desc);
+	if (ret < 0)
+		return ret;
+
 	new->irq = irq;
 
 	/*
@@ -1400,6 +1404,7 @@ out_thread:
 		put_task_struct(t);
 	}
 out_mput:
+	chip_pm_put(desc);
 	module_put(desc->owner);
 	return ret;
 }
@@ -1513,6 +1518,7 @@ static struct irqaction *__free_irq(unsigned int irq, void *dev_id)
 		}
 	}
 
+	chip_pm_put(desc);
 	module_put(desc->owner);
 	kfree(action->secondary);
 	return action;
@@ -1799,6 +1805,7 @@ static struct irqaction *__free_percpu_irq(unsigned int irq, void __percpu *dev_
 
 	unregister_handler_proc(irq, action);
 
+	chip_pm_put(desc);
 	module_put(desc->owner);
 	return action;
 
-- 
2.1.4