Documentation: serial: move GPIO kernel-doc to the functions

The GPIO uart functions are documented in Documentation. Move and
transform this documentation into kernel-doc directly in the code and
reference it in Documentation using kernel-doc:.

This makes it easier to update, maintain and check by the build.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220728061056.20799-3-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/driver-api/serial/driver.rst

@@ -94,31 +94,7 @@ Modem control lines via GPIO
 
 Some helpers are provided in order to set/get modem control lines via GPIO.
 
-mctrl_gpio_init(port, idx):
-	This will get the {cts,rts,...}-gpios from device tree if they are
-	present and request them, set direction etc, and return an
-	allocated structure. `devm_*` functions are used, so there's no need
-	to call mctrl_gpio_free().
-	As this sets up the irq handling make sure to not handle changes to the
-	gpio input lines in your driver, too.
-
-mctrl_gpio_free(dev, gpios):
-	This will free the requested gpios in mctrl_gpio_init().
-	As `devm_*` functions are used, there's generally no need to call
-	this function.
-
-mctrl_gpio_to_gpiod(gpios, gidx)
-	This returns the gpio_desc structure associated to the modem line
-	index.
-
-mctrl_gpio_set(gpios, mctrl):
-	This will sets the gpios according to the mctrl state.
-
-mctrl_gpio_get(gpios, mctrl):
-	This will update mctrl with the gpios values.
-
-mctrl_gpio_enable_ms(gpios):
-	Enables irqs and handling of changes to the ms lines.
-
-mctrl_gpio_disable_ms(gpios):
-	Disables irqs and handling of changes to the ms lines.
+.. kernel-doc:: drivers/tty/serial/serial_mctrl_gpio.c
+   :identifiers: mctrl_gpio_init mctrl_gpio_free mctrl_gpio_to_gpiod
+           mctrl_gpio_set mctrl_gpio_get mctrl_gpio_enable_ms
+           mctrl_gpio_disable_ms

drivers/tty/serial/serial_mctrl_gpio.c

@@ -42,6 +42,13 @@ static bool mctrl_gpio_flags_is_dir_out(unsigned int idx)
 	return mctrl_gpios_desc[idx].flags & GPIOD_FLAGS_BIT_DIR_OUT;
 }
 
+/**
+ * mctrl_gpio_set - set gpios according to mctrl state
+ * @gpios: gpios to set
+ * @mctrl: state to set
+ *
+ * Set the gpios according to the mctrl state.
+ */
 void mctrl_gpio_set(struct mctrl_gpios *gpios, unsigned int mctrl)
 {
 	enum mctrl_gpio_idx i;
@@ -63,6 +70,12 @@ void mctrl_gpio_set(struct mctrl_gpios *gpios, unsigned int mctrl)
 }
 EXPORT_SYMBOL_GPL(mctrl_gpio_set);
 
+/**
+ * mctrl_gpio_to_gpiod - obtain gpio_desc of modem line index
+ * @gpios: gpios to look into
+ * @gidx: index of the modem line
+ * Returns: the gpio_desc structure associated to the modem line index
+ */
 struct gpio_desc *mctrl_gpio_to_gpiod(struct mctrl_gpios *gpios,
 				      enum mctrl_gpio_idx gidx)
 {
@@ -73,6 +86,14 @@ struct gpio_desc *mctrl_gpio_to_gpiod(struct mctrl_gpios *gpios,
 }
 EXPORT_SYMBOL_GPL(mctrl_gpio_to_gpiod);
 
+/**
+ * mctrl_gpio_get - update mctrl with the gpios values.
+ * @gpios: gpios to get the info from
+ * @mctrl: mctrl to set
+ * Returns: modified mctrl (the same value as in @mctrl)
+ *
+ * Update mctrl with the gpios values.
+ */
 unsigned int mctrl_gpio_get(struct mctrl_gpios *gpios, unsigned int *mctrl)
 {
 	enum mctrl_gpio_idx i;
@@ -189,6 +210,17 @@ static irqreturn_t mctrl_gpio_irq_handle(int irq, void *context)
 	return IRQ_HANDLED;
 }
 
+/**
+ * mctrl_gpio_init - initialize uart gpios
+ * @port: port to initialize gpios for
+ * @idx: index of the gpio in the @port's device
+ *
+ * This will get the {cts,rts,...}-gpios from device tree if they are present
+ * and request them, set direction etc, and return an allocated structure.
+ * `devm_*` functions are used, so there's no need to call mctrl_gpio_free().
+ * As this sets up the irq handling, make sure to not handle changes to the
+ * gpio input lines in your driver, too.
+ */
 struct mctrl_gpios *mctrl_gpio_init(struct uart_port *port, unsigned int idx)
 {
 	struct mctrl_gpios *gpios;
@@ -235,6 +267,14 @@ struct mctrl_gpios *mctrl_gpio_init(struct uart_port *port, unsigned int idx)
 }
 EXPORT_SYMBOL_GPL(mctrl_gpio_init);
 
+/**
+ * mctrl_gpio_free - explicitly free uart gpios
+ * @dev: uart port's device
+ * @gpios: gpios structure to be freed
+ *
+ * This will free the requested gpios in mctrl_gpio_init(). As `devm_*`
+ * functions are used, there's generally no need to call this function.
+ */
 void mctrl_gpio_free(struct device *dev, struct mctrl_gpios *gpios)
 {
 	enum mctrl_gpio_idx i;
@@ -253,6 +293,10 @@ void mctrl_gpio_free(struct device *dev, struct mctrl_gpios *gpios)
 }
 EXPORT_SYMBOL_GPL(mctrl_gpio_free);
 
+/**
+ * mctrl_gpio_enable_ms - enable irqs and handling of changes to the ms lines
+ * @gpios: gpios to enable
+ */
 void mctrl_gpio_enable_ms(struct mctrl_gpios *gpios)
 {
 	enum mctrl_gpio_idx i;
@@ -278,6 +322,10 @@ void mctrl_gpio_enable_ms(struct mctrl_gpios *gpios)
 }
 EXPORT_SYMBOL_GPL(mctrl_gpio_enable_ms);
 
+/**
+ * mctrl_gpio_disable_ms - disable irqs and handling of changes to the ms lines
+ * @gpios: gpios to disable
+ */
 void mctrl_gpio_disable_ms(struct mctrl_gpios *gpios)
 {
 	enum mctrl_gpio_idx i;