serial: samsung: Add support for early console

This patch adds support for early console initialized from device tree
and kernel command line to all variants of Samsung serial driver.

Signed-off-by: Tomasz Figa <t.figa@samsung.com>
[mszyprow: added support for command line based initialization,
           fixed comments, added documentation]
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Alim Akhtar <alim.akhtar@samsung.com>
Tested-by: Alim Akhtar <alim.akhtar@samsung.com>
Tested-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 4df73da11adc586344ad6474ccb66f09ee22d66e..e855697f54c5b22164021eae3506eed9b74bd532 100644 (file)
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -970,6 +970,18 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 
                smh     Use ARM semihosting calls for early console.
 
+               s3c2410,<addr>
+               s3c2412,<addr>
+               s3c2440,<addr>
+               s3c6400,<addr>
+               s5pv210,<addr>
+               exynos4210,<addr>
+                       Use early console provided by serial driver available
+                       on Samsung SoCs, requires selecting proper type and
+                       a correct base address of the selected UART port. The
+                       serial port must already be setup and configured.
+                       Options are not yet supported.
+
        earlyprintk=    [X86,SH,BLACKFIN,ARM,M68k]
                        earlyprintk=vga
                        earlyprintk=efi

diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index 35677f75a1d8ddf3dcbd336ce43ecf4ea3454e0d..c63317e87c331c72999fbb78906587764502d2bb 100644 (file)
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -241,6 +241,7 @@ config SERIAL_SAMSUNG
        tristate "Samsung SoC serial support"
        depends on PLAT_SAMSUNG || ARCH_EXYNOS
        select SERIAL_CORE
+       select SERIAL_EARLYCON
        help
          Support for the on-chip UARTs on the Samsung S3C24XX series CPUs,
          providing /dev/ttySAC0, 1 and 2 (note, some machines may not

diff --git a/drivers/tty/serial/samsung.c b/drivers/tty/serial/samsung.c
index 024e5ecee98512b587b7c34bfdb36c89f454ffef..a6bef8dcdc3cbb0c323622839ac124cc2f042191 100644 (file)
--- a/drivers/tty/serial/samsung.c
+++ b/drivers/tty/serial/samsung.c
@@ -2403,6 +2403,109 @@ static struct platform_driver samsung_serial_driver = {
 
 module_platform_driver(samsung_serial_driver);
 
+/*
+ * Early console.
+ */
+
+struct samsung_early_console_data {
+       u32 txfull_mask;
+};
+
+static void samsung_early_busyuart(struct uart_port *port)
+{
+       while (!(readl(port->membase + S3C2410_UTRSTAT) & S3C2410_UTRSTAT_TXFE))
+               ;
+}
+
+static void samsung_early_busyuart_fifo(struct uart_port *port)
+{
+       struct samsung_early_console_data *data = port->private_data;
+
+       while (readl(port->membase + S3C2410_UFSTAT) & data->txfull_mask)
+               ;
+}
+
+static void samsung_early_putc(struct uart_port *port, int c)
+{
+       if (readl(port->membase + S3C2410_UFCON) & S3C2410_UFCON_FIFOMODE)
+               samsung_early_busyuart_fifo(port);
+       else
+               samsung_early_busyuart(port);
+
+       writeb(c, port->membase + S3C2410_UTXH);
+}
+
+static void samsung_early_write(struct console *con, const char *s, unsigned n)
+{
+       struct earlycon_device *dev = con->data;
+
+       uart_console_write(&dev->port, s, n, samsung_early_putc);
+}
+
+static int __init samsung_early_console_setup(struct earlycon_device *device,
+                                             const char *opt)
+{
+       if (!device->port.membase)
+               return -ENODEV;
+
+       device->con->write = samsung_early_write;
+       return 0;
+}
+
+/* S3C2410 */
+static struct samsung_early_console_data s3c2410_early_console_data = {
+       .txfull_mask = S3C2410_UFSTAT_TXFULL,
+};
+
+static int __init s3c2410_early_console_setup(struct earlycon_device *device,
+                                             const char *opt)
+{
+       device->port.private_data = &s3c2410_early_console_data;
+       return samsung_early_console_setup(device, opt);
+}
+OF_EARLYCON_DECLARE(s3c2410, "samsung,s3c2410-uart",
+                       s3c2410_early_console_setup);
+EARLYCON_DECLARE(s3c2410, s3c2410_early_console_setup);
+
+/* S3C2412, S3C2440, S3C64xx */
+static struct samsung_early_console_data s3c2440_early_console_data = {
+       .txfull_mask = S3C2440_UFSTAT_TXFULL,
+};
+
+static int __init s3c2440_early_console_setup(struct earlycon_device *device,
+                                             const char *opt)
+{
+       device->port.private_data = &s3c2440_early_console_data;
+       return samsung_early_console_setup(device, opt);
+}
+OF_EARLYCON_DECLARE(s3c2412, "samsung,s3c2412-uart",
+                       s3c2440_early_console_setup);
+OF_EARLYCON_DECLARE(s3c2440, "samsung,s3c2440-uart",
+                       s3c2440_early_console_setup);
+OF_EARLYCON_DECLARE(s3c6400, "samsung,s3c6400-uart",
+                       s3c2440_early_console_setup);
+EARLYCON_DECLARE(s3c2412, s3c2440_early_console_setup);
+EARLYCON_DECLARE(s3c2440, s3c2440_early_console_setup);
+EARLYCON_DECLARE(s3c6400, s3c2440_early_console_setup);
+
+/* S5PV210, EXYNOS */
+static struct samsung_early_console_data s5pv210_early_console_data = {
+       .txfull_mask = S5PV210_UFSTAT_TXFULL,
+};
+
+static int __init s5pv210_early_console_setup(struct earlycon_device *device,
+                                             const char *opt)
+{
+       device->port.private_data = &s5pv210_early_console_data;
+       return samsung_early_console_setup(device, opt);
+}
+OF_EARLYCON_DECLARE(s5pv210, "samsung,s5pv210-uart",
+                       s5pv210_early_console_setup);
+OF_EARLYCON_DECLARE(exynos4210, "samsung,exynos4210-uart",
+                       s5pv210_early_console_setup);
+EARLYCON_DECLARE(s5pv210, s5pv210_early_console_setup);
+EARLYCON_DECLARE(exynos4210, s5pv210_early_console_setup);
+
 MODULE_ALIAS("platform:samsung-uart");
 MODULE_DESCRIPTION("Samsung SoC Serial port driver");
 MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>");