servo_micro: Allow setting the baud rate for usart

We set the baud rate in increments of 100 baud, to avoid
overflowing the 16-bit wValue integer (921600 is the highest we
are likely to use).

Also, increment the buffer size for USART3 to 1024 bytes. That
helps a bit to avoid losing characters, but we still can't keep
up if the host is printing at maximum speed.

BRANCH=servo
BUG=chromium:876651
TEST=baud usart2/3/4 115200 in servo_micro console
TEST=dut-control cpu_uart_baudrate:921600
     seq 1 1000 shows numbers 1 to 226 before buffer overflows

Change-Id: Ifca266189f93def493f207dd29d2cceca4d8d68f
Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1189782
Reviewed-by: Nick Sanders <nsanders@chromium.org>

1 files changed, 34 insertions, 1 deletions

diff --git a/board/servo_micro/board.c b/board/servo_micro/board.c
index a665b3dfe8..a06978b84d 100644
--- a/board/servo_micro/board.c
+++ b/board/servo_micro/board.c
@@ -101,7 +101,7 @@ USB_STREAM_CONFIG_USART_IFACE(usart2_usb,
 static struct usart_config const usart3;
 struct usb_stream_config const usart3_usb;
 
-static struct queue const usart3_to_usb = QUEUE_DIRECT(128, uint8_t,
+static struct queue const usart3_to_usb = QUEUE_DIRECT(1024, uint8_t,
 	usart3.producer, usart3_usb.consumer);
 static struct queue const usb_to_usart3 = QUEUE_DIRECT(64, uint8_t,
 	usart3_usb.producer, usart3.consumer);
@@ -203,6 +203,39 @@ DECLARE_CONSOLE_COMMAND(parity, command_uart_parity,
 			"Set parity on uart");
 
 /******************************************************************************
+ * Set baud rate setting on usarts.
+ */
+static int command_uart_baud(int argc, char **argv)
+{
+	int baud = 0;
+	struct usart_config const *usart;
+	char *e;
+
+	if ((argc < 2) || (argc > 3))
+		return EC_ERROR_PARAM_COUNT;
+
+	if (!strcasecmp(argv[1], "usart2"))
+		usart = &usart2;
+	else if (!strcasecmp(argv[1], "usart3"))
+		usart = &usart3;
+	else if (!strcasecmp(argv[1], "usart4"))
+		usart = &usart4;
+	else
+		return EC_ERROR_PARAM1;
+
+	baud = strtoi(argv[2], &e, 0);
+	if (*e || baud < 0)
+		return EC_ERROR_PARAM2;
+
+	usart_set_baud(usart, baud);
+
+	return EC_SUCCESS;
+}
+DECLARE_CONSOLE_COMMAND(baud, command_uart_baud,
+			"usart[2|3|4] rate",
+			"Set baud rate on uart");
+
+/******************************************************************************
  * Commands for sending the magic non-I2C handshake over I2C bus wires to an
  * ITE IT8320 EC chip to enable direct firmware update (DFU) over I2C mode.
  */