Earlycon allows to have an early debugging console that doesn't need
to be statically configured in the kernel config, like earlyprintk,
but is set up through the stdout-path DT property.
This allows to have the early debugging always built into the
kernel and enabled on demand without clashing between different boards
or architectures.
Signed-off-by: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
---
drivers/tty/serial/Kconfig | 1 +
drivers/tty/serial/imx.c | 32 ++++++++++++++++++++++++++++++++
2 files changed, 33 insertions(+)
diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index 15b4079a335e..da6799d0bb35 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -582,6 +582,7 @@ config SERIAL_IMX_CONSOLE
bool "Console on IMX serial port"
depends on SERIAL_IMX=y
select SERIAL_CORE_CONSOLE
+ select SERIAL_EARLYCON if OF
help
If you have enabled the serial port on the Freescale IMX
CPU you can make it the console by answering Y to this option.
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 54fdc7866ea1..c07642438c92 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -1796,6 +1796,38 @@ static struct console imx_console = {
};
#define IMX_CONSOLE &imx_console
+
+#ifdef CONFIG_OF
+static void imx_console_early_putchar(struct uart_port *port, int ch)
+{
+ while (readl_relaxed(port->membase + IMX21_UTS) & UTS_TXFULL)
+ cpu_relax();
+
+ writel_relaxed(ch, port->membase + URTX0);
+}
+
+static void imx_console_early_write(struct console *con, const char *s,
+ unsigned count)
+{
+ struct earlycon_device *dev = con->data;
+
+ uart_console_write(&dev->port, s, count, imx_console_early_putchar);
+}
+
+static int __init
+imx_console_early_setup(struct earlycon_device *dev, const char *opt)
+{
+ if (!dev->port.membase)
+ return -ENODEV;
+
+ dev->con->write = imx_console_early_write;
+
+ return 0;
+}
+OF_EARLYCON_DECLARE(ec_imx6q, "fsl,imx6q-uart", imx_console_early_setup);
+OF_EARLYCON_DECLARE(ec_imx21, "fsl,imx21-uart", imx_console_early_setup);
+#endif
+
#else
#define IMX_CONSOLE NULL
#endif
--
2.5.0
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