[U-Boot,5/6] kerneldoc: Annotate drivers/serial/serial.c

diff --git a/drivers/serial/serial.c b/drivers/serial/serial.c
index 57e3b75..7eb4838 100644
--- a/drivers/serial/serial.c
+++ b/drivers/serial/serial.c
@@ -33,10 +33,27 @@  DECLARE_GLOBAL_DATA_PTR;
 static struct serial_device *serial_devices;
 static struct serial_device *serial_current;
 
+/**
+ * serial_null() - Void registration routine of a serial driver
+ *
+ * This routine implements a void registration routine of a serial driver. The
+ * registration routine of a particular driver is aliased to this empty function
+ * in case the driver is not compiled into U-Boot.
+ */
 static void serial_null(void)
 {
 }
 
+/**
+ * serial_initfunc() - Do a forward declaration of driver registration routine
+ * @name:	Name of the real driver registration routine.
+ *
+ * This macro expands onto forward declaration of a driver registration routine,
+ * which is then used below in serial_initialize() function. The declaration is
+ * made weak and aliases to serial_null() so in case the driver is not compiled
+ * in, the function is still declared and can be used, but aliases to
+ * serial_null() and thus is optimized away.
+ */
 #define serial_initfunc(name)					\
 	void name(void)						\
 		__attribute__((weak, alias("serial_null")));
@@ -94,6 +111,15 @@  serial_initfunc(s3c44b0_serial_initialize);
 serial_initfunc(sa1100_serial_initialize);
 serial_initfunc(sh_serial_initialize);
 
+/**
+ * serial_register() - Register serial driver with serial driver core
+ * @dev:	Pointer to the serial driver structure
+ *
+ * This function registers the serial driver supplied via @dev with serial
+ * driver core, thus making U-Boot aware of it and making it available for
+ * U-Boot to use. On platforms that still require manual relocation of constant
+ * variables, relocation of the supplied structure is performed.
+ */
 void serial_register(struct serial_device *dev)
 {
 #ifdef CONFIG_NEEDS_MANUAL_RELOC
@@ -117,6 +143,14 @@  void serial_register(struct serial_device *dev)
 	serial_devices = dev;
 }
 
+/**
+ * serial_initialize() - Register all compiled-in serial port drivers
+ *
+ * This function registers all serial port drivers that are compiled into
+ * the U-Boot binary with the serial core, thus making them available to
+ * U-Boot to use. Lastly, this function assigns a default serial port to
+ * the serial core. That serial port is then used as a default output.
+ */
 void serial_initialize(void)
 {
 	mpc8xx_serial_initialize();
@@ -175,6 +209,13 @@  void serial_initialize(void)
 	serial_assign(default_serial_console()->name);
 }
 
+/**
+ * serial_stdio_init() - Register serial ports with STDIO core
+ *
+ * This function generates a proxy driver for each serial port driver. These
+ * proxy drivers then register with the STDIO core, making the serial drivers
+ * available as STDIO devices.
+ */
 void serial_stdio_init(void)
 {
 	struct stdio_dev dev;
@@ -199,6 +240,17 @@  void serial_stdio_init(void)
 	}
 }
 
+/**
+ * serial_assign() - Select the serial output device by name
+ * @name:	Name of the serial driver to be used as default output
+ *
+ * This function configures the serial output multiplexing by selecting which
+ * serial device will be used as default. In case the STDIO "serial" device is
+ * selected as stdin/stdout/stderr, the serial device previously configured by
+ * this function will be used for the particular operation.
+ *
+ * Returns 0 on success, negative on error.
+ */
 int serial_assign(const char *name)
 {
 	struct serial_device *s;
@@ -213,6 +265,12 @@  int serial_assign(const char *name)
 	return -EINVAL;
 }
 
+/**
+ * serial_reinit_all() - Reinitialize all compiled-in serial ports
+ *
+ * This function reinitializes all serial ports that are compiled into U-Boot
+ * by calling their serial_start() functions.
+ */
 void serial_reinit_all(void)
 {
 	struct serial_device *s;
@@ -221,6 +279,20 @@  void serial_reinit_all(void)
 		s->start();
 }
 
+/**
+ * get_current() - Return pointer to currently selected serial port
+ *
+ * This function returns a pointer to currently selected serial port. The
+ * currently selected serial port is altered by serial_assign() function.
+ *
+ * In case this function is called before relocation or before any serial
+ * port is configured, this function calls default_serial_console() to
+ * determine the serial port. Otherwise, the configured serial port is
+ * returned.
+ *
+ * Returns pointer to the currently selected serial port on success,
+ * NULL on error.
+ */
 static struct serial_device *get_current(void)
 {
 	struct serial_device *dev;
@@ -245,36 +317,110 @@  static struct serial_device *get_current(void)
 	return dev;
 }
 
+/**
+ * serial_init() - Initialize currently selected serial port
+ *
+ * This function initializes the currently selected serial port. This usually
+ * involves setting up the registers of that particular port, enabling clock
+ * and such. This function uses the get_current() call to determine which port
+ * is selected.
+ *
+ * Returns 0 on success, negative on error.
+ */
 int serial_init(void)
 {
 	return get_current()->start();
 }
 
+/**
+ * serial_setbrg() - Configure baud-rate of currently selected serial port
+ *
+ * This function configures the baud-rate of the currently selected serial
+ * port. The baud-rate is retrieved from global data within the serial port
+ * driver. This function uses the get_current() call to determine which port
+ * is selected.
+ *
+ * Returns 0 on success, negative on error.
+ */
 void serial_setbrg(void)
 {
 	get_current()->setbrg();
 }
 
+/**
+ * serial_getc() - Read single character from currently selected serial port
+ *
+ * This function retrieves a single character from currently selected serial
+ * port. In case there is no character in the serial port fifo, this function
+ * will block and wait for the character indefinitelly. This function uses the
+ * get_current() call to determine which port is selected.
+ *
+ * Returns the character on success, negative on error.
+ */
 int serial_getc(void)
 {
 	return get_current()->getc();
 }
 
+/**
+ * serial_tstc() - Test if data is available on currently selected serial port
+ *
+ * This function tests if a single character is available on currently selected
+ * serial port. In case there is no character in the serial port buffer, this
+ * function will not block. This function uses the get_current() call to
+ * determine which port is selected.
+ *
+ * Returns positive if character is available, zero otherwise.
+ */
 int serial_tstc(void)
 {
 	return get_current()->tstc();
 }
 
+/**
+ * serial_putc() - Output single character via currently selected serial port
+ * @c:	Single character to be output from the serial port.
+ *
+ * This function outputs a single character via currently selected serial port.
+ * This character is written into the fifo of the port and the function waits
+ * for the character to be emitted, therefore this function may block for a
+ * short amount of time. This function uses the get_current() call to determine
+ * which port is selected.
+ */
 void serial_putc(const char c)
 {
 	get_current()->putc(c);
 }
 
+/**
+ * serial_puts() - Output string via currently selected serial port
+ * @s:	Zero-terminated string to be output from the serial port.
+ *
+ * This function outputs a zero-terminated string via currently selected serial
+ * port. This function behaves as an accelerator in case the hardware has a
+ * larger fifo buffer. The whole string that is to be output is available to
+ * the function implementing the hardware manipulation. The function waits
+ * for the whole string to be emitted, therefore this function may block for a
+ * some amount of time. This function uses the get_current() call to determine
+ * which port is selected.
+ */
 void serial_puts(const char *s)
 {
 	get_current()->puts(s);
 }
 
+/**
+ * default_serial_puts() - Output string by calling serial_putc() in loop
+ * @s:	Zero-terminated string to be output from the serial port.
+ *
+ * This function outputs a zero-terminated string by calling serial_putc()
+ * in a loop. Most drivers do not fifo larger than one byte, thus this function
+ * precisely implements their serial_puts().
+ *
+ * To optimize the number of get_current() calls, this function only calls
+ * get_current() once and then directly accesses the putc() call of the
+ * &struct serial_device .
+ */
 void default_serial_puts(const char *s)
 {
 	struct serial_device *dev = get_current();
@@ -285,6 +431,17 @@  void default_serial_puts(const char *s)
 #if CONFIG_POST & CONFIG_SYS_POST_UART
 static const int bauds[] = CONFIG_SYS_BAUDRATE_TABLE;
 
+/**
+ * uart_post_test() - Test the currently selected serial port using POST
+ * @flags:	POST framework flags
+ *
+ * Do a loopback test of the currently selected serial port. This function
+ * is only useful in the context of the POST testing framwork. The serial
+ * port is firstly configured into loopback mode and then characters are
+ * sent through it.
+ *
+ * Returns 0 on success, value otherwise.
+ */
 /* Mark weak until post/cpu/.../uart.c migrate over */
 __weak
 int uart_post_test(int flags)