serial: mxc: Add debug uart support

Add support for the debug UART to assist with early debugging.
Enable it for i.CoreM6 as an example.

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

diff --git a/configs/imx6qdl_icore_mmc_defconfig b/configs/imx6qdl_icore_mmc_defconfig
index 8c0cc96ba861363e52b7e7df46f361b5f6537d23..2b1bb3d5911677e8a6f06689460cdb2555bdb86c 100644 (file)
--- a/configs/imx6qdl_icore_mmc_defconfig
+++ b/configs/imx6qdl_icore_mmc_defconfig
@@ -45,3 +45,7 @@ CONFIG_PINCTRL_IMX6=y
 CONFIG_MXC_UART=y
 CONFIG_IMX_THERMAL=y
 CONFIG_VIDEO_IPUV3=y
+CONFIG_DEBUG_UART=y
+CONFIG_DEBUG_UART_MXC=y
+CONFIG_DEBUG_UART_BASE=0x021f0000
+CONFIG_DEBUG_UART_CLOCK=24000000

diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index b7dd2ac1038d7ca03454c13c5614478dc7e18aba..97cef7edbda69a08856614270d7d323493e083fc 100644 (file)
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -248,6 +248,14 @@ config DEBUG_UART_PIC32
          will need to provide parameters to make this work. The driver will
          be available until the real driver model serial is running.
 
+config DEBUG_UART_MXC
+       bool "IMX Serial port"
+       depends on MXC_UART
+       help
+         Select this to enable a debug UART using the serial_mxc driver. You
+         will need to provide parameters to make this work. The driver will
+         be available until the real driver model serial is running.
+
 config DEBUG_UART_UNIPHIER
        bool "UniPhier on-chip UART"
        depends on ARCH_UNIPHIER

diff --git a/drivers/serial/serial_mxc.c b/drivers/serial/serial_mxc.c
index c8c36e5e19cf5167bc6d652768cc1b0fb9354302..cce80a8559e2527f15502cd9e4e07fbb0557403e 100644 (file)
--- a/drivers/serial/serial_mxc.c
+++ b/drivers/serial/serial_mxc.c
@@ -357,3 +357,29 @@ U_BOOT_DRIVER(serial_mxc) = {
        .flags = DM_FLAG_PRE_RELOC,
 };
 #endif
+
+#ifdef CONFIG_DEBUG_UART_MXC
+#include <debug_uart.h>
+
+static inline void _debug_uart_init(void)
+{
+       struct mxc_uart *base = (struct mxc_uart *)CONFIG_DEBUG_UART_BASE;
+
+       _mxc_serial_init(base);
+       _mxc_serial_setbrg(base, CONFIG_DEBUG_UART_CLOCK,
+                          CONFIG_BAUDRATE, false);
+}
+
+static inline void _debug_uart_putc(int ch)
+{
+       struct mxc_uart *base = (struct mxc_uart *)CONFIG_DEBUG_UART_BASE;
+
+       while (!(readl(&base->ts) & UTS_TXEMPTY))
+               WATCHDOG_RESET();
+
+       writel(ch, &base->txd);
+}
+
+DEBUG_UART_FUNCS
+
+#endif