[U-Boot] [PATCH] serial: serial_stm32: Add reset support

[Patrice Chotard]

In some cases, UART is configured by early boot stage.
To be sure of the initial state of UART and to avoid
spurious chars on console, reset the serial block before
configuring it.

Signed-off-by: Patrice Chotard <patrice.chotard at st.com>
---

 drivers/serial/serial_stm32.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/serial/serial_stm32.c b/drivers/serial/serial_stm32.c
index 31b43ee88dd7..e31c87b9ac5a 100644
--- a/drivers/serial/serial_stm32.c
+++ b/drivers/serial/serial_stm32.c
@@ -7,6 +7,7 @@
 #include <common.h>
 #include <clk.h>
 #include <dm.h>
+#include <reset.h>
 #include <serial.h>
 #include <watchdog.h>
 #include <asm/io.h>
@@ -171,6 +172,7 @@ static int stm32_serial_probe(struct udevice *dev)
 {
 	struct stm32x7_serial_platdata *plat = dev_get_platdata(dev);
 	struct clk clk;
+	struct reset_ctl reset;
 	int ret;
 
 	plat->uart_info = (struct stm32_uart_info *)dev_get_driver_data(dev);
@@ -185,6 +187,13 @@ static int stm32_serial_probe(struct udevice *dev)
 		return ret;
 	}
 
+	ret = reset_get_by_index(dev, 0, &reset);
+	if (!ret) {
+		reset_assert(&reset);
+		udelay(2);
+		reset_deassert(&reset);
+	}
+
 	plat->clock_rate = clk_get_rate(&clk);
 	if (plat->clock_rate < 0) {
 		clk_disable(&clk);
-- 
1.9.1