[PATCH v6 2/3] 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.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Janani Sunil <janani.sunil@analog.com>
---
 drivers/gpio/gpio-regmap.c  | 80 +++++++++++++++++++++++++++++++++++++++++----
 include/linux/gpio/regmap.h |  2 ++
 2 files changed, 76 insertions(+), 6 deletions(-)

diff --git a/drivers/gpio/gpio-regmap.c b/drivers/gpio/gpio-regmap.c
index ae6fa42b00a4..2f5f45b84cc9 100644
--- a/drivers/gpio/gpio-regmap.c
+++ b/drivers/gpio/gpio-regmap.c
@@ -6,11 +6,13 @@
  */
 
 #include <linux/bits.h>
+#include <linux/cleanup.h>
 #include <linux/compiler_attributes.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>
@@ -23,6 +25,8 @@
 struct gpio_regmap {
 	struct device *parent;
 	struct regmap *regmap;
+	struct device *pm_dev;
+
 	struct gpio_chip gpio_chip;
 
 	int reg_stride;
@@ -79,6 +83,33 @@ 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)
+
+#define GPIO_REGMAP_RUNTIME_ACQUIRE(_gpio, _var) \
+	ACQUIRE(gpio_regmap_runtime_try, _var)(_gpio)
+
+#define GPIO_REGMAP_RUNTIME_ACQUIRE_ERR(_var_ptr) \
+	ACQUIRE_ERR(gpio_regmap_runtime, _var_ptr)
+
 static int gpio_regmap_get(struct gpio_chip *chip, unsigned int offset)
 {
 	struct gpio_regmap *gpio = gpiochip_get_data(chip);
@@ -91,7 +122,13 @@ static int gpio_regmap_get(struct gpio_chip *chip, unsigned int offset)
 	else
 		base = gpio_regmap_addr(gpio->reg_set_base);
 
-	ret = gpio->reg_mask_xlate(gpio, GPIO_REGMAP_GET_OP, base, offset, &reg, &mask);
+	GPIO_REGMAP_RUNTIME_ACQUIRE(gpio, pm);
+	ret = GPIO_REGMAP_RUNTIME_ACQUIRE_ERR(&pm);
+	if (ret)
+		return ret;
+
+	ret = gpio->reg_mask_xlate(gpio, GPIO_REGMAP_GET_OP, base, offset,
+				   &reg, &mask);
 	if (ret)
 		return ret;
 
@@ -114,7 +151,13 @@ static int gpio_regmap_set(struct gpio_chip *chip, unsigned int offset,
 	unsigned int reg, mask, mask_val;
 	int ret;
 
-	ret = gpio->reg_mask_xlate(gpio, GPIO_REGMAP_SET_OP, base, offset, &reg, &mask);
+	GPIO_REGMAP_RUNTIME_ACQUIRE(gpio, pm);
+	ret = GPIO_REGMAP_RUNTIME_ACQUIRE_ERR(&pm);
+	if (ret)
+		return ret;
+
+	ret = gpio->reg_mask_xlate(gpio, GPIO_REGMAP_SET_OP, base, offset,
+				   &reg, &mask);
 	if (ret)
 		return ret;
 
@@ -146,6 +189,11 @@ static int gpio_regmap_set_with_clear(struct gpio_chip *chip,
 	unsigned int base, reg, mask, value = 0;
 	int ret;
 
+	GPIO_REGMAP_RUNTIME_ACQUIRE(gpio, pm);
+	ret = GPIO_REGMAP_RUNTIME_ACQUIRE_ERR(&pm);
+	if (ret)
+		return ret;
+
 	if (val)
 		base = gpio_regmap_addr(gpio->reg_set_base);
 	else
@@ -208,7 +256,13 @@ static int gpio_regmap_get_direction(struct gpio_chip *chip,
 		return -ENOTSUPP;
 	}
 
-	ret = gpio->reg_mask_xlate(gpio, GPIO_REGMAP_GET_DIR_OP, base, offset, &reg, &mask);
+	GPIO_REGMAP_RUNTIME_ACQUIRE(gpio, pm);
+	ret = GPIO_REGMAP_RUNTIME_ACQUIRE_ERR(&pm);
+	if (ret)
+		return ret;
+
+	ret = gpio->reg_mask_xlate(gpio, GPIO_REGMAP_GET_DIR_OP, base, offset,
+				   &reg, &mask);
 	if (ret)
 		return ret;
 
@@ -262,7 +316,13 @@ static int gpio_regmap_set_direction(struct gpio_chip *chip,
 		return -ENOTSUPP;
 	}
 
-	ret = gpio->reg_mask_xlate(gpio, GPIO_REGMAP_SET_DIR_OP, base, offset, &reg, &mask);
+	GPIO_REGMAP_RUNTIME_ACQUIRE(gpio, pm);
+	ret = GPIO_REGMAP_RUNTIME_ACQUIRE_ERR(&pm);
+	if (ret)
+		return ret;
+
+	ret = gpio->reg_mask_xlate(gpio, GPIO_REGMAP_SET_DIR_OP, base, offset,
+				   &reg, &mask);
 	if (ret)
 		return ret;
 
@@ -293,6 +353,11 @@ static int gpio_regmap_direction_output(struct gpio_chip *chip,
 	struct gpio_regmap *gpio = gpiochip_get_data(chip);
 	int ret;
 
+	GPIO_REGMAP_RUNTIME_ACQUIRE(gpio, pm);
+	ret = GPIO_REGMAP_RUNTIME_ACQUIRE_ERR(&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
@@ -304,7 +369,9 @@ 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);
 }
@@ -399,6 +466,7 @@ 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;
@@ -406,7 +474,7 @@ 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 6f52c140e50d..6fe0877717cb 100644
--- a/include/linux/gpio/regmap.h
+++ b/include/linux/gpio/regmap.h
@@ -46,6 +46,7 @@ enum gpio_regmap_operation {
  * @parent:		The parent device
  * @regmap:		The regmap used to access the registers
  *			given, the name of the device is used
+ * @pm_dev:		(Optional) Device to use for runtime power management.
  * @fwnode:		(Optional) The firmware node.
  *			If not given, the fwnode of the parent is used.
  * @label:		(Optional) Descriptive name for GPIO controller.
@@ -117,6 +118,7 @@ enum gpio_regmap_operation {
 struct gpio_regmap_config {
 	struct device *parent;
 	struct regmap *regmap;
+	struct device *pm_dev;
 	struct fwnode_handle *fwnode;
 
 	const char *label;

-- 
2.43.0