genirq: Introduce irq_chip_get/set_parent_state calls

On certain QTI chipsets some GPIOs are direct-connect interrupts to the
GIC to be used as regular interrupt lines. When the GPIOs are not used
for interrupt generation the interrupt line is disabled. But disabling
the interrupt at GIC does not prevent the interrupt to be reported as
pending at GIC_ISPEND. Later, when drivers call enable_irq() on the
interrupt, an unwanted interrupt occurs.

Introduce get and set methods for irqchip's parent to clear it's pending
irq state. This then can be invoked by the GPIO interrupt controller on
the parents in it hierarchy to clear the interrupt before enabling the
interrupt.

Signed-off-by: Maulik Shah <mkshah@codeaurora.org>
Signed-off-by: Lina Iyer <ilina@codeaurora.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/1573855915-9841-7-git-send-email-ilina@codeaurora.org

[updated commit text and minor code fixes]

1 files changed, 44 insertions, 0 deletions

diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index b76703b2c0af..b3fa2d87d2f3 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -1298,6 +1298,50 @@ EXPORT_SYMBOL_GPL(handle_fasteoi_mask_irq);
 #endif /* CONFIG_IRQ_FASTEOI_HIERARCHY_HANDLERS */
 
 /**
+ * irq_chip_set_parent_state - set the state of a parent interrupt.
+ *
+ * @data: Pointer to interrupt specific data
+ * @which: State to be restored (one of IRQCHIP_STATE_*)
+ * @val: Value corresponding to @which
+ *
+ * Conditional success, if the underlying irqchip does not implement it.
+ */
+int irq_chip_set_parent_state(struct irq_data *data,
+			      enum irqchip_irq_state which,
+			      bool val)
+{
+	data = data->parent_data;
+
+	if (!data || !data->chip->irq_set_irqchip_state)
+		return 0;
+
+	return data->chip->irq_set_irqchip_state(data, which, val);
+}
+EXPORT_SYMBOL_GPL(irq_chip_set_parent_state);
+
+/**
+ * irq_chip_get_parent_state - get the state of a parent interrupt.
+ *
+ * @data: Pointer to interrupt specific data
+ * @which: one of IRQCHIP_STATE_* the caller wants to know
+ * @state: a pointer to a boolean where the state is to be stored
+ *
+ * Conditional success, if the underlying irqchip does not implement it.
+ */
+int irq_chip_get_parent_state(struct irq_data *data,
+			      enum irqchip_irq_state which,
+			      bool *state)
+{
+	data = data->parent_data;
+
+	if (!data || !data->chip->irq_get_irqchip_state)
+		return 0;
+
+	return data->chip->irq_get_irqchip_state(data, which, state);
+}
+EXPORT_SYMBOL_GPL(irq_chip_get_parent_state);
+
+/**
  * irq_chip_enable_parent - Enable the parent interrupt (defaults to unmask if
  * NULL)
  * @data:	Pointer to interrupt specific data