[PATCH] gpiolib-legacy: Request gpio without touching direction

[Einar Vading <einar.vading@xxxxxxxx>]

Adds function to request a gpio without touching the direction of the
gpio upon export.

This is useful if some user space application know what state the gpio
should be in and it is important that this state is kept during reboot.

Signed-off-by: Einar Vading <einarv@xxxxxxxx>
---
 drivers/gpio/gpiolib-legacy.c | 50 +++++++++++++++++++++++++----------
 include/asm-generic/gpio.h    |  2 ++
 include/linux/gpio.h          |  6 +++++
 3 files changed, 44 insertions(+), 14 deletions(-)

diff --git a/drivers/gpio/gpiolib-legacy.c b/drivers/gpio/gpiolib-legacy.c
index 8b830996fe..521c8099bf 100644
--- a/drivers/gpio/gpiolib-legacy.c
+++ b/drivers/gpio/gpiolib-legacy.c
@@ -11,13 +11,8 @@ void gpio_free(unsigned gpio)
 }
 EXPORT_SYMBOL_GPL(gpio_free);
 
-/**
- * gpio_request_one - request a single GPIO with initial configuration
- * @gpio:	the GPIO number
- * @flags:	GPIO configuration as specified by GPIOF_*
- * @label:	a literal description string of this GPIO
- */
-int gpio_request_one(unsigned gpio, unsigned long flags, const char *label)
+static int _gpio_request_one(unsigned gpio, unsigned long flags,
+			     const char *label, bool set_dir)
 {
 	struct gpio_desc *desc;
 	int err;
@@ -41,14 +36,16 @@ int gpio_request_one(unsigned gpio, unsigned long flags, const char *label)
 	if (flags & GPIOF_ACTIVE_LOW)
 		set_bit(FLAG_ACTIVE_LOW, &desc->flags);
 
-	if (flags & GPIOF_DIR_IN)
-		err = gpiod_direction_input(desc);
-	else
-		err = gpiod_direction_output_raw(desc,
-				(flags & GPIOF_INIT_HIGH) ? 1 : 0);
+	if (set_dir) {
+		if (flags & GPIOF_DIR_IN)
+			err = gpiod_direction_input(desc);
+		else
+			err = gpiod_direction_output_raw(desc,
+					(flags & GPIOF_INIT_HIGH) ? 1 : 0);
 
-	if (err)
-		goto free_gpio;
+		if (err)
+			goto free_gpio;
+	}
 
 	if (flags & GPIOF_EXPORT) {
 		err = gpiod_export(desc, flags & GPIOF_EXPORT_CHANGEABLE);
@@ -62,8 +59,33 @@ int gpio_request_one(unsigned gpio, unsigned long flags, const char *label)
 	gpiod_free(desc);
 	return err;
 }
+
+/**
+ * gpio_request_one - request a single GPIO with initial configuration
+ * @gpio:	the GPIO number
+ * @flags:	GPIO configuration as specified by GPIOF_*
+ * @label:	a literal description string of this GPIO
+ */
+int gpio_request_one(unsigned gpio, unsigned long flags, const char *label)
+{
+	return _gpio_request_one(gpio, flags, label, true);
+}
 EXPORT_SYMBOL_GPL(gpio_request_one);
 
+/**
+ * gpio_request_one_keepdir - request a single GPIO with initial configuration
+ *			      but without setting direction on export.
+ * @gpio:	the GPIO number
+ * @flags:	GPIO configuration as specified by GPIOF_*
+ * @label:	a literal description string of this GPIO
+ */
+int gpio_request_one_keepdir(unsigned gpio, unsigned long flags,
+			     const char *label)
+{
+	return _gpio_request_one(gpio, flags, label, false);
+}
+EXPORT_SYMBOL_GPL(gpio_request_one_keepdir);
+
 int gpio_request(unsigned gpio, const char *label)
 {
 	struct gpio_desc *desc = gpio_to_desc(gpio);
diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h
index 8b74cff7c0..9e7d64d04e 100644
--- a/include/asm-generic/gpio.h
+++ b/include/asm-generic/gpio.h
@@ -115,6 +115,8 @@ static inline int __gpio_to_irq(unsigned gpio)
 }
 
 extern int gpio_request_one(unsigned gpio, unsigned long flags, const char *label);
+extern int gpio_request_one_keepdir(unsigned gpio, unsigned long flags,
+		const char *label);
 extern int gpio_request_array(const struct gpio *array, size_t num);
 extern void gpio_free_array(const struct gpio *array, size_t num);
 
diff --git a/include/linux/gpio.h b/include/linux/gpio.h
index 8ef7fc0ce0..adca31cd88 100644
--- a/include/linux/gpio.h
+++ b/include/linux/gpio.h
@@ -113,6 +113,12 @@ static inline int gpio_request_one(unsigned gpio,
 	return -ENOSYS;
 }
 
+static inline int gpio_request_one_keepdir(unsigned gpio,
+		unsigned long flags, const char *label)
+{
+	return -ENOSYS;
+}
+
 static inline int gpio_request_array(const struct gpio *array, size_t num)
 {
 	return -ENOSYS;
-- 
2.17.0

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