[PATCH 1/2] genirq: add chip_{suspend,resume} PM support to irq_chip

[Brian Norris <computersforpeace@gmail.com>]

Some (admittedly odd) irqchips perform functions that are not directly
related to any of their child IRQ lines, and therefore need to perform
some tasks during suspend/resume regardless of whether there are
any "installed" interrupts for the irqchip. However, the current
generic-chip framework does not call the chip's irq_{suspend,resume}
when there are no interrupts installed (this makes sense, because there
are no irq_data objects for such a call to be made).

More specifically, irq-bcm7120-l2 configures both a forwarding mask
(which affects other top-level GIC IRQs) and a second-level interrupt
mask (for managing its own child interrupts). The former must be
saved/restored on suspend/resume, even when there's nothing to do for
the latter.

This patch adds a second set of suspend/resume hooks to irq_chip, this
time to represent *chip* suspend/resume, rather than IRQ suspend/resume.
These callbacks will always be called for an irqchip and are based on
the per-chip irq_chip_generic struct, rather than the per-IRQ irq_data
struct.

The original problem report is described in extra detail here:
http://lkml.kernel.org/g/20150619224123.GL4917@ld-irv-0074

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
---
 include/linux/irq.h       | 10 ++++++++++
 kernel/irq/generic-chip.c |  6 ++++++
 2 files changed, 16 insertions(+)

diff --git a/include/linux/irq.h b/include/linux/irq.h
index de3213d271ff..2a672d2434a5 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -293,6 +293,8 @@ static inline irq_hw_number_t irqd_to_hwirq(struct irq_data *d)
 	return d->hwirq;
 }
 
+struct irq_chip_generic;
+
 /**
  * struct irq_chip - hardware interrupt chip descriptor
  *
@@ -317,6 +319,12 @@ static inline irq_hw_number_t irqd_to_hwirq(struct irq_data *d)
  * @irq_suspend:	function called from core code on suspend once per chip
  * @irq_resume:		function called from core code on resume once per chip
  * @irq_pm_shutdown:	function called from core code on shutdown once per chip
+ * @chip_suspend:	function called from core code on suspend once per
+ *			chip; for handling chip details even when no interrupts
+ *			are in use
+ * @chip_resume:	function called from core code on resume once per chip;
+ *			for handling chip details even when no interrupts are
+ *			in use
  * @irq_calc_mask:	Optional function to set irq_data.mask for special cases
  * @irq_print_chip:	optional to print special chip info in show_interrupts
  * @irq_request_resources:	optional to request resources before calling
@@ -357,6 +365,8 @@ struct irq_chip {
 	void		(*irq_suspend)(struct irq_data *data);
 	void		(*irq_resume)(struct irq_data *data);
 	void		(*irq_pm_shutdown)(struct irq_data *data);
+	void		(*chip_suspend)(struct irq_chip_generic *gc);
+	void		(*chip_resume)(struct irq_chip_generic *gc);
 
 	void		(*irq_calc_mask)(struct irq_data *data);
 
diff --git a/kernel/irq/generic-chip.c b/kernel/irq/generic-chip.c
index 15b370daf234..fe25e72d5d13 100644
--- a/kernel/irq/generic-chip.c
+++ b/kernel/irq/generic-chip.c
@@ -553,6 +553,9 @@ static int irq_gc_suspend(void)
 			if (data)
 				ct->chip.irq_suspend(data);
 		}
+
+		if (ct->chip.chip_suspend)
+			ct->chip.chip_suspend(gc);
 	}
 	return 0;
 }
@@ -564,6 +567,9 @@ static void irq_gc_resume(void)
 	list_for_each_entry(gc, &gc_list, list) {
 		struct irq_chip_type *ct = gc->chip_types;
 
+		if (ct->chip.chip_resume)
+			ct->chip.chip_resume(gc);
+
 		if (ct->chip.irq_resume) {
 			struct irq_data *data = irq_gc_get_irq_data(gc);
 
-- 
1.9.1

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