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 CONFIG_PM is selected in the kernel
configuration, 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>
Reviewed-by: Kevin Hilman <khilman@baylibre.com>
Reviewed-by: Marc Zyngier <redacted>
---
  include/linux/irq.h    |  4 ++++
  kernel/irq/chip.c      | 35 +++++++++++++++++++++++++++++++++++
  kernel/irq/internals.h |  1 +
  kernel/irq/manage.c    | 31 ++++++++++++++++++++++++++++++-
  4 files changed, 70 insertions(+), 1 deletion(-)

diff --git a/include/linux/irq.h b/include/linux/irq.h
index 4d758a7c604a..6c92a847394d 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h

@@ -315,6 +315,7 @@ static inline irq_hw_number_t irqd_to_hwirq(struct irq_data *d)
  /**
   * struct irq_chip - hardware interrupt chip descriptor
   *
+ * @parent_device:	pointer to parent device for irqchip
   * @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)

@@ -354,6 +355,7 @@ static inline irq_hw_number_t irqd_to_hwirq(struct irq_data *d)
   * @flags:		chip specific flags
   */
  struct irq_chip {
+	struct device	*parent_device;
  	const char	*name;
  	unsigned int	(*irq_startup)(struct irq_data *data);
  	void		(*irq_shutdown)(struct irq_data *data);

@@ -488,6 +490,8 @@ extern void handle_bad_irq(struct irq_desc *desc);
  extern void handle_nested_irq(unsigned int irq);
  
  extern int irq_chip_compose_msi_msg(struct irq_data *data, struct msi_msg *msg);
+extern int irq_chip_pm_get(struct irq_data *data);
+extern int irq_chip_pm_put(struct irq_data *data);
  #ifdef	CONFIG_IRQ_DOMAIN_HIERARCHY
  extern void irq_chip_enable_parent(struct irq_data *data);
  extern void irq_chip_disable_parent(struct irq_data *data);

diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index 2f9f2b0e79f2..b09226e895c7 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c

@@ -1093,3 +1093,38 @@ int irq_chip_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
  
  	return 0;
  }
+
+/**
+ * irq_chip_pm_get - Enable power for an IRQ chip
+ * @data:	Pointer to interrupt specific data
+ *
+ * Enable the power to the IRQ chip referenced by the interrupt data
+ * structure.
+ */
+int irq_chip_pm_get(struct irq_data *data)
+{
+	int retval = 0;
+
+	if (IS_ENABLED(CONFIG_PM) && data->chip->parent_device)
+		retval = pm_runtime_get_sync(data->chip->parent_device);