[PATCH 5.15 73/96] gpio: Allow per-parent interrupt data

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

From: Marc Zyngier <maz@kernel.org>

[ Upstream commit cfe6807d82e97e81c3209dca9448f091e1448a57 ]

The core gpiolib code is able to deal with multiple interrupt parents
for a single gpio irqchip. It however only allows a single piece
of data to be conveyed to all flow handlers (either the gpio_chip
or some other, driver-specific data).

This means that drivers have to go through some interesting dance
to find the correct context, something that isn't great in interrupt
context (see aebdc8abc9db86e2bd33070fc2f961012fff74b4 for a prime
example).

Instead, offer an optional way for a pinctrl/gpio driver to provide
an array of pointers which gets used to provide the correct context
to the flow handler.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Joey Gouly <joey.gouly@arm.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20211026175815.52703-2-joey.gouly@arm.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Stable-dep-of: 8c00914e5438 ("gpiolib: Fix GPIO chip IRQ initialization restriction")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpio/gpiolib.c      |  9 +++++++--
 include/linux/gpio/driver.h | 19 +++++++++++++++++--
 2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 8c041a8dd9d8f..099fe2e39bd63 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1578,9 +1578,14 @@ static int gpiochip_add_irqchip(struct gpio_chip *gc,
 	}
 
 	if (gc->irq.parent_handler) {
-		void *data = gc->irq.parent_handler_data ?: gc;
-
 		for (i = 0; i < gc->irq.num_parents; i++) {
+			void *data;
+
+			if (gc->irq.per_parent_data)
+				data = gc->irq.parent_handler_data_array[i];
+			else
+				data = gc->irq.parent_handler_data ?: gc;
+
 			/*
 			 * The parent IRQ chip is already using the chip_data
 			 * for this IRQ chip, so our callbacks simply use the
diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
index 11c26ae7b4fa4..65df2ce96f0b1 100644
--- a/include/linux/gpio/driver.h
+++ b/include/linux/gpio/driver.h
@@ -168,11 +168,18 @@ struct gpio_irq_chip {
 
 	/**
 	 * @parent_handler_data:
+	 * @parent_handler_data_array:
 	 *
 	 * Data associated, and passed to, the handler for the parent
-	 * interrupt.
+	 * interrupt. Can either be a single pointer if @per_parent_data
+	 * is false, or an array of @num_parents pointers otherwise.  If
+	 * @per_parent_data is true, @parent_handler_data_array cannot be
+	 * NULL.
 	 */
-	void *parent_handler_data;
+	union {
+		void *parent_handler_data;
+		void **parent_handler_data_array;
+	};
 
 	/**
 	 * @num_parents:
@@ -203,6 +210,14 @@ struct gpio_irq_chip {
 	 */
 	bool threaded;
 
+	/**
+	 * @per_parent_data:
+	 *
+	 * True if parent_handler_data_array describes a @num_parents
+	 * sized array to be used as parent data.
+	 */
+	bool per_parent_data;
+
 	/**
 	 * @init_hw: optional routine to initialize hardware before
 	 * an IRQ chip will be added. This is quite useful when
-- 
2.39.2