[PATCH 3/3] gpio: regmap: Support a custom ->to_irq() hook

[Aidan MacDonald <aidanmacdonald.0x0@xxxxxxxxx>]

Some GPIO chips require a custom to_irq() callback for mapping
their IRQs, eg. because their interrupts come from a parent IRQ
chip where the GPIO offset doesn't map 1-to-1 with hwirq number.

Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@xxxxxxxxx>
---
 drivers/gpio/gpio-regmap.c  | 17 +++++++++++++++++
 include/linux/gpio/regmap.h |  4 ++++
 2 files changed, 21 insertions(+)

diff --git a/drivers/gpio/gpio-regmap.c b/drivers/gpio/gpio-regmap.c
index 4bc01329fb14..d11b202e51fd 100644
--- a/drivers/gpio/gpio-regmap.c
+++ b/drivers/gpio/gpio-regmap.c
@@ -34,6 +34,8 @@ struct gpio_regmap {
 				unsigned int *reg, unsigned int *mask,
 				unsigned int *values);
 
+	int (*to_irq)(struct gpio_regmap *gpio, unsigned int offset);
+
 	void *driver_data;
 };
 
@@ -193,6 +195,13 @@ static int gpio_regmap_direction_output(struct gpio_chip *chip,
 	return gpio_regmap_set_direction(chip, offset, true);
 }
 
+static int gpio_regmap_to_irq(struct gpio_chip *chip, unsigned int offset)
+{
+	struct gpio_regmap *gpio = gpiochip_get_data(chip);
+
+	return gpio->to_irq(gpio, offset);
+}
+
 void *gpio_regmap_get_drvdata(struct gpio_regmap *gpio)
 {
 	return gpio->driver_data;
@@ -242,6 +251,10 @@ struct gpio_regmap *gpio_regmap_register(const struct gpio_regmap_config *config
 	if (config->reg_field_xlate && config->reg_mask_xlate)
 		return ERR_PTR(-EINVAL);
 
+	/* an irq_domain will override the to_irq hook, so don't allow both */
+	if (config->irq_domain && config->to_irq)
+		return ERR_PTR(-EINVAL);
+
 	gpio = kzalloc(sizeof(*gpio), GFP_KERNEL);
 	if (!gpio)
 		return ERR_PTR(-ENOMEM);
@@ -253,6 +266,7 @@ struct gpio_regmap *gpio_regmap_register(const struct gpio_regmap_config *config
 	gpio->reg_stride = config->reg_stride;
 	gpio->reg_mask_xlate = config->reg_mask_xlate;
 	gpio->reg_field_xlate = config->reg_field_xlate;
+	gpio->to_irq = config->to_irq;
 	gpio->reg_dat_base = config->reg_dat_base;
 	gpio->reg_set_base = config->reg_set_base;
 	gpio->reg_clr_base = config->reg_clr_base;
@@ -302,6 +316,9 @@ struct gpio_regmap *gpio_regmap_register(const struct gpio_regmap_config *config
 		chip->direction_output = gpio_regmap_direction_output;
 	}
 
+	if (gpio->to_irq)
+		chip->to_irq = gpio_regmap_to_irq;
+
 	ret = gpiochip_add_data(chip, gpio);
 	if (ret < 0)
 		goto err_free_gpio;
diff --git a/include/linux/gpio/regmap.h b/include/linux/gpio/regmap.h
index 47acea8cca32..9755854d6747 100644
--- a/include/linux/gpio/regmap.h
+++ b/include/linux/gpio/regmap.h
@@ -45,6 +45,8 @@ struct regmap;
  *			to register, mask, and field values. If not given
  *			the default gpio_regmap_field_xlate() is used, which
  *			is implemented in terms of ->reg_mask_xlate.
+ * @to_irq:		(Optional) hook for supporting custom IRQ mappings,
+ *			behaves the same as the gpio_chip to_irq hook.
  * @drvdata:		(Optional) Pointer to driver specific data which is
  *			not used by gpio-remap but is provided "as is" to the
  *			driver callback(s).
@@ -102,6 +104,8 @@ struct gpio_regmap_config {
 				unsigned int *reg, unsigned int *mask,
 				unsigned int *values);
 
+	int (*to_irq)(struct gpio_regmap *gpio, unsigned int offset);
+
 	void *drvdata;
 };
 
-- 
2.35.1