diff options
Diffstat (limited to 'drivers/serial/serial.c')
| -rw-r--r-- | drivers/serial/serial.c | 165 |
1 files changed, 165 insertions, 0 deletions
diff --git a/drivers/serial/serial.c b/drivers/serial/serial.c index 18b9ed4330..e0886d562e 100644 --- a/drivers/serial/serial.c +++ b/drivers/serial/serial.c @@ -33,10 +33,28 @@ 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() - Forward declare 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"))); @@ -95,6 +113,16 @@ 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 @@ -118,6 +146,15 @@ 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(); @@ -177,6 +214,13 @@ 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; @@ -201,6 +245,18 @@ 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; @@ -215,6 +271,12 @@ 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; @@ -223,6 +285,21 @@ 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; @@ -247,36 +324,113 @@ 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 character from currently selected serial port + * + * This function retrieves a character from currently selected serial + * port. In case there is no character waiting on the serial port, + * this function will block and wait for the character to appear. 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 one or more characters are available on + * currently selected serial port. This function never blocks. 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 character via currently selected serial port + * @c: Single character to be output from the serial port. + * + * This function outputs a character via currently selected serial + * port. This character is passed to the serial port driver responsible + * for controlling the hardware. The hardware may still be in process + * of transmitting another character, 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 can queue multiple characters for transfer. + * The whole string that is to be output is available to the function + * implementing the hardware manipulation. Transmitting the whole + * string may take some time, thus this function may block for 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 support queueing more than one byte for + * transfer, 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(); @@ -287,6 +441,17 @@ 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) |