[U-Boot] [PATCH 7/7] serial: mxc: Add debug uart support

[Jagan Teki <jagannadh.teki@gmail.com>]

From: Jagan Teki <jagan@amarulasolutions.com>

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>
---
 configs/imx6qdl_icore_mmc_defconfig |  4 ++++
 drivers/serial/Kconfig              |  8 ++++++++
 drivers/serial/serial_mxc.c         | 26 ++++++++++++++++++++++++++
 3 files changed, 38 insertions(+)

diff --git a/configs/imx6qdl_icore_mmc_defconfig b/configs/imx6qdl_icore_mmc_defconfig
index 4ab1fac..24010ec 100644
--- a/configs/imx6qdl_icore_mmc_defconfig
+++ b/configs/imx6qdl_icore_mmc_defconfig
@@ -44,3 +44,7 @@ CONFIG_IMX_THERMAL=y
 CONFIG_VIDEO_IPUV3=y
 CONFIG_PHYLIB=y
 CONFIG_PHY_SMSC=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 58fc7cd..32a3374 100644
--- 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 0bcd15c..18ff421 100644
--- 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
-- 
1.9.1