From: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Date: Fri, 4 Feb 2022 15:36:49 +0000 (+0100)
Subject: efi_loader: fix text output for Uart() DP nodes
X-Git-Url: http://git.dujemihanovic.xyz/?a=commitdiff_plain;h=915623c0d3f504dce8a2310c1ddf5dcc638e5d93;p=u-boot.git

efi_loader: fix text output for Uart() DP nodes

The UEFI specification concerning Uart() device path nodes has been
clarified:

Parity and stop bits can either both use keywords or both use
numbers but numbers and keywords should not be mixed.

Let's go for keywords as this is what EDK II does. For illegal
values fall back to numbers.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
---

diff --git a/lib/efi_loader/efi_device_path_to_text.c b/lib/efi_loader/efi_device_path_to_text.c
index 97b3d3e815..4d73954ef8 100644
--- a/lib/efi_loader/efi_device_path_to_text.c
+++ b/lib/efi_loader/efi_device_path_to_text.c
@@ -122,16 +122,26 @@ static char *dp_msging(char *s, struct efi_device_path *dp)
 	case DEVICE_PATH_SUB_TYPE_MSG_UART: {
 		struct efi_device_path_uart *uart =
 			(struct efi_device_path_uart *)dp;
-		s += sprintf(s, "Uart(%lld,%d,%d,", uart->baud_rate,
-			     uart->data_bits, uart->parity);
-		switch (uart->stop_bits) {
-		case 2:
-			s += sprintf(s, "1.5)");
-			break;
-		default:
+		const char parity_str[6] = {'D', 'N', 'E', 'O', 'M', 'S'};
+		const char *stop_bits_str[4] = { "D", "1", "1.5", "2" };
+
+		s += sprintf(s, "Uart(%lld,%d,", uart->baud_rate,
+			     uart->data_bits);
+
+		/*
+		 * Parity and stop bits can either both use keywords or both use
+		 * numbers but numbers and keywords should not be mixed. Let's
+		 * go for keywords as this is what EDK II does. For illegal
+		 * values fall back to numbers.
+		 */
+		if (uart->parity < 6)
+			s += sprintf(s, "%c,", parity_str[uart->parity]);
+		else
+			s += sprintf(s, "%d,", uart->parity);
+		if (uart->stop_bits < 4)
+			s += sprintf(s, "%s)", stop_bits_str[uart->stop_bits]);
+		else
 			s += sprintf(s, "%d)", uart->stop_bits);
-			break;
-		}
 		break;
 	}
 	case DEVICE_PATH_SUB_TYPE_MSG_USB: {