[PATCH v4 12/14] gpio: regmap: Add optional runtime PM support

[Janani Sunil <janani.sunil@analog.com>]

Some gpio-regmap consumers share their regmap with a parent device that
may be runtime suspended. GPIO register accesses must resume that device
first.

Add an optional pm_dev field and acquire it before register translation
or access. Release it using runtime autosuspend after each operation.
Keep the device active across the complete direction-output sequence and
propagate failure when setting the initial output value.

Signed-off-by: Janani Sunil <janani.sunil@analog.com>
---
 drivers/gpio/gpio-regmap.c  | 62 +++++++++++++++++++++++++++++++++++++++++++--
 include/linux/gpio/regmap.h |  2 ++
 2 files changed, 62 insertions(+), 2 deletions(-)

diff --git a/drivers/gpio/gpio-regmap.c b/drivers/gpio/gpio-regmap.c
index 0012e03d0d4e..3e7030e47483 100644
--- a/drivers/gpio/gpio-regmap.c
+++ b/drivers/gpio/gpio-regmap.c
@@ -6,10 +6,12 @@
  */
 
 #include <linux/bits.h>
+#include <linux/cleanup.h>
 #include <linux/device.h>
 #include <linux/err.h>
 #include <linux/io.h>
 #include <linux/module.h>
+#include <linux/pm_runtime.h>
 #include <linux/regmap.h>
 #include <linux/slab.h>
 #include <linux/types.h>
@@ -31,6 +33,7 @@ struct gpio_regmap {
 	unsigned int reg_clr_base;
 	unsigned int reg_dir_in_base;
 	unsigned int reg_dir_out_base;
+	struct device *pm_dev;
 	unsigned long *fixed_direction_mask;
 	unsigned long *fixed_direction_output;
 
@@ -67,6 +70,27 @@ static int gpio_regmap_simple_xlate(struct gpio_regmap *gpio,
 	return 0;
 }
 
+static int gpio_regmap_runtime_get(struct gpio_regmap *gpio)
+{
+	if (!gpio->pm_dev)
+		return 0;
+
+	return pm_runtime_get_active(gpio->pm_dev, RPM_TRANSPARENT);
+}
+
+static void gpio_regmap_runtime_put(struct gpio_regmap *gpio)
+{
+	if (!gpio->pm_dev)
+		return;
+
+	pm_runtime_put_autosuspend(gpio->pm_dev);
+}
+
+DEFINE_GUARD(gpio_regmap_runtime, struct gpio_regmap *,
+	     gpio_regmap_runtime_get(_T), gpio_regmap_runtime_put(_T))
+DEFINE_GUARD_COND(gpio_regmap_runtime, _try,
+		  gpio_regmap_runtime_get(_T), _RET == 0)
+
 static int gpio_regmap_get(struct gpio_chip *chip, unsigned int offset)
 {
 	struct gpio_regmap *gpio = gpiochip_get_data(chip);
@@ -79,6 +103,11 @@ static int gpio_regmap_get(struct gpio_chip *chip, unsigned int offset)
 	else
 		base = gpio_regmap_addr(gpio->reg_set_base);
 
+	ACQUIRE(gpio_regmap_runtime_try, pm)(gpio);
+	ret = ACQUIRE_ERR(gpio_regmap_runtime_try, &pm);
+	if (ret)
+		return ret;
+
 	ret = gpio->reg_mask_xlate(gpio, base, offset, &reg, &mask);
 	if (ret)
 		return ret;
@@ -102,6 +131,11 @@ static int gpio_regmap_set(struct gpio_chip *chip, unsigned int offset,
 	unsigned int reg, mask, mask_val;
 	int ret;
 
+	ACQUIRE(gpio_regmap_runtime_try, pm)(gpio);
+	ret = ACQUIRE_ERR(gpio_regmap_runtime_try, &pm);
+	if (ret)
+		return ret;
+
 	ret = gpio->reg_mask_xlate(gpio, base, offset, &reg, &mask);
 	if (ret)
 		return ret;
@@ -127,6 +161,11 @@ static int gpio_regmap_set_with_clear(struct gpio_chip *chip,
 	unsigned int base, reg, mask;
 	int ret;
 
+	ACQUIRE(gpio_regmap_runtime_try, pm)(gpio);
+	ret = ACQUIRE_ERR(gpio_regmap_runtime_try, &pm);
+	if (ret)
+		return ret;
+
 	if (val)
 		base = gpio_regmap_addr(gpio->reg_set_base);
 	else
@@ -182,6 +221,11 @@ static int gpio_regmap_get_direction(struct gpio_chip *chip,
 		return -ENOTSUPP;
 	}
 
+	ACQUIRE(gpio_regmap_runtime_try, pm)(gpio);
+	ret = ACQUIRE_ERR(gpio_regmap_runtime_try, &pm);
+	if (ret)
+		return ret;
+
 	ret = gpio->reg_mask_xlate(gpio, base, offset, &reg, &mask);
 	if (ret)
 		return ret;
@@ -236,6 +280,11 @@ static int gpio_regmap_set_direction(struct gpio_chip *chip,
 		return -ENOTSUPP;
 	}
 
+	ACQUIRE(gpio_regmap_runtime_try, pm)(gpio);
+	ret = ACQUIRE_ERR(gpio_regmap_runtime_try, &pm);
+	if (ret)
+		return ret;
+
 	ret = gpio->reg_mask_xlate(gpio, base, offset, &reg, &mask);
 	if (ret)
 		return ret;
@@ -260,6 +309,11 @@ static int gpio_regmap_direction_output(struct gpio_chip *chip,
 	struct gpio_regmap *gpio = gpiochip_get_data(chip);
 	int ret;
 
+	ACQUIRE(gpio_regmap_runtime_try, pm)(gpio);
+	ret = ACQUIRE_ERR(gpio_regmap_runtime_try, &pm);
+	if (ret)
+		return ret;
+
 	/*
 	 * First check if this is gonna work on a fixed direction line,
 	 * if it doesn't (i.e. this is a fixed input line), then do not
@@ -271,7 +325,9 @@ static int gpio_regmap_direction_output(struct gpio_chip *chip,
 			return ret;
 	}
 
-	gpio_regmap_set(chip, offset, value);
+	ret = gpio_regmap_set(chip, offset, value);
+	if (ret)
+		return ret;
 
 	return gpio_regmap_set_direction(chip, offset, true);
 }
@@ -323,6 +379,7 @@ struct gpio_regmap *gpio_regmap_register(const struct gpio_regmap_config *config
 	gpio->reg_clr_base = config->reg_clr_base;
 	gpio->reg_dir_in_base = config->reg_dir_in_base;
 	gpio->reg_dir_out_base = config->reg_dir_out_base;
+	gpio->pm_dev = config->pm_dev;
 
 	chip = &gpio->gpio_chip;
 	chip->parent = config->parent;
@@ -330,7 +387,8 @@ struct gpio_regmap *gpio_regmap_register(const struct gpio_regmap_config *config
 	chip->base = -1;
 	chip->names = config->names;
 	chip->label = config->label ?: dev_name(config->parent);
-	chip->can_sleep = regmap_might_sleep(config->regmap);
+	chip->can_sleep = config->pm_dev ||
+			  regmap_might_sleep(config->regmap);
 	chip->init_valid_mask = config->init_valid_mask;
 
 	chip->request = gpiochip_generic_request;
diff --git a/include/linux/gpio/regmap.h b/include/linux/gpio/regmap.h
index 06255756710d..eceb31b89f50 100644
--- a/include/linux/gpio/regmap.h
+++ b/include/linux/gpio/regmap.h
@@ -34,6 +34,7 @@ struct regmap;
  * @ngpio_per_reg:	(Optional) Number of GPIOs per register
  * @irq_domain:		(Optional) IRQ domain if the controller is
  *			interrupt-capable
+ * @pm_dev:		(Optional) Device to use for runtime power management.
  * @reg_mask_xlate:     (Optional) Translates base address and GPIO
  *			offset to a register/bitmask pair. If not
  *			given the default gpio_regmap_simple_xlate()
@@ -95,6 +96,7 @@ struct gpio_regmap_config {
 	int reg_stride;
 	int ngpio_per_reg;
 	struct irq_domain *irq_domain;
+	struct device *pm_dev;
 	unsigned long *fixed_direction_mask;
 	unsigned long *fixed_direction_output;
 

-- 
2.43.0