[PATCH 2/3] gpio: regmap: Support combined GPIO and pin control drivers

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

Allow gpio-regmap to be used for the GPIO portion of a combined
pin control and GPIO driver by setting the has_pinctrl flag. This
flag will cause GPIO direction set ops to be implemented as calls
to pinctrl_gpio_direction_input/output() instead of updating the
direction set registers directly.

Note that reg_dir_out/in_base is still required for implementing
the GPIO chip's ->get_direction() callback.

Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@xxxxxxxxx>
---
 drivers/gpio/gpio-regmap.c  | 20 ++++++++++++++++++++
 include/linux/gpio/regmap.h |  6 ++++++
 2 files changed, 26 insertions(+)

diff --git a/drivers/gpio/gpio-regmap.c b/drivers/gpio/gpio-regmap.c
index 9256b922c654..4bc01329fb14 100644
--- a/drivers/gpio/gpio-regmap.c
+++ b/drivers/gpio/gpio-regmap.c
@@ -24,6 +24,8 @@ struct gpio_regmap {
 	unsigned int reg_dir_in_base;
 	unsigned int reg_dir_out_base;
 
+	unsigned int has_pinctrl:1;
+
 	int (*reg_mask_xlate)(struct gpio_regmap *gpio, unsigned int base,
 			      unsigned int offset, unsigned int *reg,
 			      unsigned int *mask);
@@ -170,14 +172,24 @@ static int gpio_regmap_set_direction(struct gpio_chip *chip,
 static int gpio_regmap_direction_input(struct gpio_chip *chip,
 				       unsigned int offset)
 {
+	struct gpio_regmap *gpio = gpiochip_get_data(chip);
+
+	if (gpio->has_pinctrl)
+		return pinctrl_gpio_direction_input(chip->base + offset);
+
 	return gpio_regmap_set_direction(chip, offset, false);
 }
 
 static int gpio_regmap_direction_output(struct gpio_chip *chip,
 					unsigned int offset, int value)
 {
+	struct gpio_regmap *gpio = gpiochip_get_data(chip);
+
 	gpio_regmap_set(chip, offset, value);
 
+	if (gpio->has_pinctrl)
+		return pinctrl_gpio_direction_output(chip->base + offset);
+
 	return gpio_regmap_set_direction(chip, offset, true);
 }
 
@@ -218,6 +230,14 @@ struct gpio_regmap *gpio_regmap_register(const struct gpio_regmap_config *config
 	if (config->reg_dir_out_base && config->reg_dir_in_base)
 		return ERR_PTR(-EINVAL);
 
+	/*
+	 * we need a direction register for implementing ->get_direction
+	 * even if ->direction_input/output is handled by pin control
+	 */
+	if (config->has_pinctrl && !(config->reg_dir_in_base ||
+				     config->reg_dir_out_base))
+		return ERR_PTR(-EINVAL);
+
 	/* only one of these should be provided */
 	if (config->reg_field_xlate && config->reg_mask_xlate)
 		return ERR_PTR(-EINVAL);
diff --git a/include/linux/gpio/regmap.h b/include/linux/gpio/regmap.h
index a673dbfe88a3..47acea8cca32 100644
--- a/include/linux/gpio/regmap.h
+++ b/include/linux/gpio/regmap.h
@@ -33,6 +33,10 @@ struct regmap;
  * @ngpio_per_reg:	Number of GPIOs per register
  * @irq_domain:		(Optional) IRQ domain if the controller is
  *			interrupt-capable
+ * @has_pinctrl:	If set, the GPIO chip is part of a combined pin control
+ *			and GPIO driver; use pinctrl_gpio_direction_input() and
+ *			pinctrl_gpio_direction_output() to implement direction
+ *			set operations.
  * @reg_mask_xlate:     (Optional) Translates base address and GPIO
  *			offset to a register/bitmask pair. If not
  *			given the default gpio_regmap_simple_xlate()
@@ -88,6 +92,8 @@ struct gpio_regmap_config {
 	int ngpio_per_reg;
 	struct irq_domain *irq_domain;
 
+	unsigned int has_pinctrl:1;
+
 	int (*reg_mask_xlate)(struct gpio_regmap *gpio, unsigned int base,
 			      unsigned int offset, unsigned int *reg,
 			      unsigned int *mask);
-- 
2.35.1