serial: atmel_usart: Support enable an early debug UART
Add support to enable an early debug UART for debugging.
Signed-off-by: Wenyou Yang <wenyou.yang@atmel.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Andreas Bießmann <andreas@biessmann.org>
diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index 9e48902..507a27d 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -98,6 +98,13 @@
driver will be available until the real driver model serial is
running.
+config DEBUG_UART_ATMEL
+ bool "Atmel USART"
+ help
+ Select this to enable a debug UART using the atmel usart 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_NS16550
bool "ns16550"
help
diff --git a/drivers/serial/atmel_usart.c b/drivers/serial/atmel_usart.c
index e450135..7674f97 100644
--- a/drivers/serial/atmel_usart.c
+++ b/drivers/serial/atmel_usart.c
@@ -11,6 +11,7 @@
#include <errno.h>
#include <watchdog.h>
#include <serial.h>
+#include <debug_uart.h>
#include <linux/compiler.h>
#include <asm/io.h>
@@ -226,3 +227,24 @@
.priv_auto_alloc_size = sizeof(struct atmel_serial_priv),
};
#endif
+
+#ifdef CONFIG_DEBUG_UART_ATMEL
+static inline void _debug_uart_init(void)
+{
+ atmel_usart3_t *usart = (atmel_usart3_t *)CONFIG_DEBUG_UART_BASE;
+
+ atmel_serial_setbrg_internal(usart, 0, CONFIG_BAUDRATE);
+}
+
+static inline void _debug_uart_putc(int ch)
+{
+ atmel_usart3_t *usart = (atmel_usart3_t *)CONFIG_DEBUG_UART_BASE;
+
+ while (!(readl(&usart->csr) & USART3_BIT(TXRDY)))
+ ;
+
+ writel(ch, &usart->thr);
+}
+
+DEBUG_UART_FUNCS
+#endif