[RFC PATCH] gpiolib: make gpiod_direction_output take a logical value, add gpiod_direction_output_raw

[Philipp Zabel <p.zabel@pengutronix.de>]

The documentation was not clear about whether gpio_direction_output should take
a logical value or the physical level on the output line, i.e. whether the
ACTIVE_LOW status would be taken into account.
This converts gpiod_direction_output to use the logical level and adds a new
gpiod_direction_output_raw for the raw value.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
---
 Documentation/gpio/consumer.txt |  1 +
 drivers/gpio/gpiolib.c          | 67 +++++++++++++++++++++++++++++------------
 include/asm-generic/gpio.h      |  2 +-
 include/linux/gpio/consumer.h   |  7 +++++
 4 files changed, 57 insertions(+), 20 deletions(-)

diff --git a/Documentation/gpio/consumer.txt b/Documentation/gpio/consumer.txt
index 07c74a3..4dc4809 100644
--- a/Documentation/gpio/consumer.txt
+++ b/Documentation/gpio/consumer.txt
@@ -150,6 +150,7 @@ raw line value:
 	void gpiod_set_raw_value(struct gpio_desc *desc, int value)
 	int gpiod_get_raw_value_cansleep(const struct gpio_desc *desc)
 	void gpiod_set_raw_value_cansleep(struct gpio_desc *desc, int value)
+	int gpiod_direction_output_raw(struct gpio_desc *desc, int value)
 
 The active-low state of a GPIO can also be queried using the following call:
 
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 85f772c..f04f1e6 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -330,9 +330,9 @@ static ssize_t gpio_direction_store(struct device *dev,
 	if (!test_bit(FLAG_EXPORT, &desc->flags))
 		status = -EIO;
 	else if (sysfs_streq(buf, "high"))
-		status = gpiod_direction_output(desc, 1);
+		status = gpiod_direction_output_raw(desc, 1);
 	else if (sysfs_streq(buf, "out") || sysfs_streq(buf, "low"))
-		status = gpiod_direction_output(desc, 0);
+		status = gpiod_direction_output_raw(desc, 0);
 	else if (sysfs_streq(buf, "in"))
 		status = gpiod_direction_input(desc);
 	else
@@ -1579,7 +1579,7 @@ int gpio_request_one(unsigned gpio, unsigned long flags, const char *label)
 	if (flags & GPIOF_DIR_IN)
 		err = gpiod_direction_input(desc);
 	else
-		err = gpiod_direction_output(desc,
+		err = gpiod_direction_output_raw(desc,
 				(flags & GPIOF_INIT_HIGH) ? 1 : 0);
 
 	if (err)
@@ -1744,28 +1744,13 @@ fail:
 }
 EXPORT_SYMBOL_GPL(gpiod_direction_input);
 
-/**
- * gpiod_direction_output - set the GPIO direction to input
- * @desc:	GPIO to set to output
- * @value:	initial output value of the GPIO
- *
- * Set the direction of the passed GPIO to output, such as gpiod_set_value() can
- * be called safely on it. The initial value of the output must be specified.
- *
- * Return 0 in case of success, else an error code.
- */
-int gpiod_direction_output(struct gpio_desc *desc, int value)
+static int _gpiod_direction_output_raw(struct gpio_desc *desc, int value)
 {
 	unsigned long		flags;
 	struct gpio_chip	*chip;
 	int			status = -EINVAL;
 	int offset;
 
-	if (!desc || !desc->chip) {
-		pr_warn("%s: invalid GPIO\n", __func__);
-		return -EINVAL;
-	}
-
 	/* GPIOs used for IRQs shall not be set as output */
 	if (test_bit(FLAG_USED_AS_IRQ, &desc->flags)) {
 		gpiod_err(desc,
@@ -1827,6 +1812,50 @@ fail:
 		gpiod_dbg(desc, "%s: gpio status %d\n", __func__, status);
 	return status;
 }
+
+/**
+ * gpiod_direction_output_raw - set the GPIO direction to output
+ * @desc:	GPIO to set to output
+ * @value:	initial output value of the GPIO
+ *
+ * Set the direction of the passed GPIO to output, such as gpiod_set_value() can
+ * be called safely on it. The initial value of the output must be specified
+ * as raw value on the physical line without regard for the ACTIVE_LOW status.
+ *
+ * Return 0 in case of success, else an error code.
+ */
+int gpiod_direction_output_raw(struct gpio_desc *desc, int value)
+{
+	if (!desc || !desc->chip) {
+		pr_warn("%s: invalid GPIO\n", __func__);
+		return -EINVAL;
+	}
+	return _gpiod_direction_output_raw(desc, value);
+}
+EXPORT_SYMBOL_GPL(gpiod_direction_output_raw);
+
+/**
+ * gpiod_direction_output - set the GPIO direction to input
+ * @desc:	GPIO to set to output
+ * @value:	initial output value of the GPIO
+ *
+ * Set the direction of the passed GPIO to output, such as gpiod_set_value() can
+ * be called safely on it. The initial value of the output must be specified
+ * as the logical value of the GPIO, i.e. taking its ACTIVE_LOW status into
+ * account.
+ *
+ * Return 0 in case of success, else an error code.
+ */
+int gpiod_direction_output(struct gpio_desc *desc, int value)
+{
+	if (!desc || !desc->chip) {
+		pr_warn("%s: invalid GPIO\n", __func__);
+		return -EINVAL;
+	}
+	if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
+		value = !value;
+	return _gpiod_direction_output_raw(desc, value);
+}
 EXPORT_SYMBOL_GPL(gpiod_direction_output);
 
 /**
diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h
index a5f56a0..23e3645 100644
--- a/include/asm-generic/gpio.h
+++ b/include/asm-generic/gpio.h
@@ -69,7 +69,7 @@ static inline int gpio_direction_input(unsigned gpio)
 }
 static inline int gpio_direction_output(unsigned gpio, int value)
 {
-	return gpiod_direction_output(gpio_to_desc(gpio), value);
+	return gpiod_direction_output_raw(gpio_to_desc(gpio), value);
 }
 
 static inline int gpio_set_debounce(unsigned gpio, unsigned debounce)
diff --git a/include/linux/gpio/consumer.h b/include/linux/gpio/consumer.h
index 4d34dbb..3879943 100644
--- a/include/linux/gpio/consumer.h
+++ b/include/linux/gpio/consumer.h
@@ -36,6 +36,7 @@ void devm_gpiod_put(struct device *dev, struct gpio_desc *desc);
 int gpiod_get_direction(const struct gpio_desc *desc);
 int gpiod_direction_input(struct gpio_desc *desc);
 int gpiod_direction_output(struct gpio_desc *desc, int value);
+int gpiod_direction_output_raw(struct gpio_desc *desc, int value);
 
 /* Value get/set from non-sleeping context */
 int gpiod_get_value(const struct gpio_desc *desc);
@@ -121,6 +122,12 @@ static inline int gpiod_direction_output(struct gpio_desc *desc, int value)
 	WARN_ON(1);
 	return -ENOSYS;
 }
+static inline int gpiod_direction_output_raw(struct gpio_desc *desc, int value)
+{
+	/* GPIO can never have been requested */
+	WARN_ON(1);
+	return -ENOSYS;
+}
 
 
 static inline int gpiod_get_value(const struct gpio_desc *desc)
-- 
1.8.5.2