[RFC PATCH 05/10] serial: mps2-uart: add support for early console
From: Vladimir Murzin <hidden>
Date: 2015-11-25 10:38:29
Also in:
linux-api, linux-arm-kernel, linux-serial, lkml
Subsystem:
the rest, tty layer and serial drivers · Maintainers:
Linus Torvalds, Greg Kroah-Hartman, Jiri Slaby
This adds support early console for MPS2 UART which can be enabled via earlycon=mps2,0x40004000 Signed-off-by: Vladimir Murzin <redacted> --- drivers/tty/serial/Kconfig | 1 + drivers/tty/serial/mps2-uart.c | 30 ++++++++++++++++++++++++++++++ 2 files changed, 31 insertions(+)
diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index b47f8fc..bb8c66b 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig@@ -1477,6 +1477,7 @@ config SERIAL_MPS2_UART_CONSOLE bool "MPS2 UART console support" depends on SERIAL_MPS2_UART select SERIAL_CORE_CONSOLE + select SERIAL_EARLYCON config SERIAL_MPS2_UART tristate "MPS2 UART port"
diff --git a/drivers/tty/serial/mps2-uart.c b/drivers/tty/serial/mps2-uart.c
index 00e882e..c2f530e 100644
--- a/drivers/tty/serial/mps2-uart.c
+++ b/drivers/tty/serial/mps2-uart.c@@ -445,6 +445,36 @@ static struct console mps2_uart_console = { #define MPS2_SERIAL_CONSOLE (&mps2_uart_console) +static void mps2_early_putchar(struct uart_port *port, int ch) +{ + + while (readb(port->membase + UARTn_STATE) & UARTn_STATE_TX_FULL) + cpu_relax(); + + writeb((unsigned char)ch, port->membase + UARTn_DATA); +} + + +static void mps2_early_write(struct console *con, const char *s, unsigned n) +{ + struct earlycon_device *dev = con->data; + + uart_console_write(&dev->port, s, n, mps2_early_putchar); +} + +static int __init mps2_early_console_setup(struct earlycon_device *device, + const char *opt) +{ + if (!device->port.membase) + return -ENODEV; + + device->con->write = mps2_early_write; + + return 0; +} +EARLYCON_DECLARE(mps2, mps2_early_console_setup); +OF_EARLYCON_DECLARE(mps2, "arm,mps2-uart", mps2_early_console_setup); + #else #define MPS2_SERIAL_CONSOLE NULL #endif
--
1.7.9.5