[PATCH v8 6/9] gpio: regmap: Add value_xlate callback

[Yu-Chun Lin]

Introduce a new optional 'value_xlate' callback. This routine allows drivers
to translate or modify the register value and mask immediately before a write
operation. It is particularly useful for hardware that requires additional
control bits, such as a write-enable bit, to be appended to the data
dynamically.

Reviewed-by: Michael Walle <mwalle@xxxxxxxxxx>
Reviewed-by: Linus Walleij <linusw@xxxxxxxxxx>
Suggested-by: Michael Walle <mwalle@xxxxxxxxxx>
Signed-off-by: Yu-Chun Lin <eleanor.lin@xxxxxxxxxxx>
---
Changes in v8:
- Add Reviewed-by tags from Michael and Linus.
- Improve kernel-doc comments for 'enum gpio_regmap_operation' and value_xlate.
---
 drivers/gpio/gpio-regmap.c  | 31 ++++++++++++++++++++++++++++++-
 include/linux/gpio/regmap.h | 15 ++++++++++++---
 2 files changed, 42 insertions(+), 4 deletions(-)

diff --git a/drivers/gpio/gpio-regmap.c b/drivers/gpio/gpio-regmap.c
index ceab805d053c..cff7db8036f7 100644
--- a/drivers/gpio/gpio-regmap.c
+++ b/drivers/gpio/gpio-regmap.c
@@ -45,6 +45,12 @@ struct gpio_regmap {
 			      unsigned int base, unsigned int offset,
 			      unsigned int *reg, unsigned int *mask);
 
+	int (*value_xlate)(struct gpio_regmap *gpio,
+			   enum gpio_regmap_operation op,
+			   unsigned int base, unsigned int offset,
+			   unsigned int reg, unsigned int *mask,
+			   unsigned int *val);
+
 	void *driver_data;
 };
 
@@ -114,6 +120,13 @@ static int gpio_regmap_set(struct gpio_chip *chip, unsigned int offset,
 	else
 		mask_val = 0;
 
+	if (gpio->value_xlate) {
+		ret = gpio->value_xlate(gpio, GPIO_REGMAP_SET_OP, base, offset,
+					reg, &mask, &mask_val);
+		if (ret)
+			return ret;
+	}
+
 	/* ignore input values which shadow the old output value */
 	if (gpio->reg_dat_base == gpio->reg_set_base)
 		ret = regmap_write_bits(gpio->regmap, reg, mask, mask_val);
@@ -127,7 +140,7 @@ static int gpio_regmap_set_with_clear(struct gpio_chip *chip,
 				      unsigned int offset, int val)
 {
 	struct gpio_regmap *gpio = gpiochip_get_data(chip);
-	unsigned int base, reg, mask;
+	unsigned int base, reg, mask, value = 0;
 	int ret;
 
 	if (val)
@@ -139,6 +152,13 @@ static int gpio_regmap_set_with_clear(struct gpio_chip *chip,
 	if (ret)
 		return ret;
 
+	if (gpio->value_xlate) {
+		ret = gpio->value_xlate(gpio, GPIO_REGMAP_SET_OP, base, offset,
+					reg, &mask, &value);
+		if (ret)
+			return ret;
+	}
+
 	return regmap_write(gpio->regmap, reg, mask);
 }
 
@@ -248,6 +268,13 @@ static int gpio_regmap_set_direction(struct gpio_chip *chip,
 	else
 		val = output ? mask : 0;
 
+	if (gpio->value_xlate) {
+		ret = gpio->value_xlate(gpio, GPIO_REGMAP_SET_DIR_OP, base, offset,
+					reg, &mask, &val);
+		if (ret)
+			return ret;
+	}
+
 	return regmap_update_bits(gpio->regmap, reg, mask, val);
 }
 
@@ -415,6 +442,8 @@ struct gpio_regmap *gpio_regmap_register(const struct gpio_regmap_config *config
 	if (!gpio->reg_mask_xlate)
 		gpio->reg_mask_xlate = gpio_regmap_simple_xlate;
 
+	gpio->value_xlate = config->value_xlate;
+
 	ret = gpiochip_add_data(chip, gpio);
 	if (ret < 0)
 		goto err_free_bitmap_output;
diff --git a/include/linux/gpio/regmap.h b/include/linux/gpio/regmap.h
index 7eebb6381296..77dbb353bc1f 100644
--- a/include/linux/gpio/regmap.h
+++ b/include/linux/gpio/regmap.h
@@ -14,13 +14,13 @@ struct regmap;
 #define GPIO_REGMAP_ADDR(addr) ((addr) ? : GPIO_REGMAP_ADDR_ZERO)
 
 /**
- * enum gpio_regmap_operation - Operation type for reg_mask_xlate callback
+ * enum gpio_regmap_operation - Operation type for gpio_regmap callbacks
  *
  * Traditionally, the operation type was inferred from the base register.
  * However, that approach does not always work — for example, when all control
  * bits of a single GPIO reside in the same register. This enum allows the
- * reg_mask_xlate callback to explicitly distinguish between operation types.
- * The user is free to choose which method to use.
+ * callbacks (reg_mask_xlate and value_xlate) to explicitly distinguish between
+ * operation types. The user is free to choose which method to use.
  *
  * Read operation:
  * @GPIO_REGMAP_GET_OP: Indicates a read operation to get the current GPIO value.
@@ -81,6 +81,11 @@ enum gpio_regmap_operation {
  *			is used.
  * @init_valid_mask:	(Optional) Routine to initialize @valid_mask, to be used
  *			if not all GPIOs are valid.
+ * @value_xlate:	(Optional) Routine to translate the register value and
+ *			mask before writing. This allows driver-specific logic
+ *			to append additional bits (like write-enable masks)
+ *			dynamically based on the current operation
+ *			(GPIO_REGMAP_SET_OP and GPIO_REGMAP_SET_DIR_OP).
  * @drvdata:		(Optional) Pointer to driver specific data which is
  *			not used by gpio-remap but is provided "as is" to the
  *			driver callback(s).
@@ -138,6 +143,10 @@ struct gpio_regmap_config {
 			       unsigned long *valid_mask,
 			       unsigned int ngpios);
 
+	int (*value_xlate)(struct gpio_regmap *gpio, enum gpio_regmap_operation,
+			   unsigned int base, unsigned int offset, unsigned int reg,
+			   unsigned int *mask, unsigned int *val);
+
 	void *drvdata;
 };
 
-- 
2.43.0