[U-Boot] [PATCH 1/1] efi_loader: environment variables for terminal size

[Heinrich Schuchardt]

Correct scrolling in EFI applications like the EFI Shell requires correct
setting of the terminal size. Detecting the terminal size over the serial
interface is often not supported. The patch introduces the environment
variables LINES and COLUMNS to set the terminal size manually.

Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
---
 doc/README.uefi              | 14 ++++++++++++++
 lib/efi_loader/efi_console.c | 15 ++++++++++++++-
 2 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/doc/README.uefi b/doc/README.uefi
index 6b9759cfed..df0cf5b7ce 100644
--- a/doc/README.uefi
+++ b/doc/README.uefi
@@ -299,6 +299,20 @@ This driver is only available if U-Boot is configured with
     CONFIG_BLK=y
     CONFIG_PARTITIONS=y
 
+## Setting the terminal size
+
+For correct scrolling the terminal size has to be known.
+
+The default terminal size is 80x25.
+
+If the environment variable 'stdout' has the value 'vidconsole', the terminal
+size is determined by querying the video console driver. Else it is tried to
+determine the terminal size by sending ESC '[18t' to the console which may
+reply with an escape sequence indicating the terminal size.
+
+It is possible to override the terminal size by setting the environment
+variables 'LINES' and 'COLUMNS'.
+
 ## TODOs as of U-Boot 2018.07
 
 * unimplemented or incompletely implemented boot services
diff --git a/lib/efi_loader/efi_console.c b/lib/efi_loader/efi_console.c
index 73f7ecf919..40e33f9fd3 100644
--- a/lib/efi_loader/efi_console.c
+++ b/lib/efi_loader/efi_console.c
@@ -224,6 +224,7 @@ static void query_console_size(void)
 {
 	const char *stdout_name = env_get("stdout");
 	int rows = 25, cols = 80;
+	char *value;
 
 	if (stdout_name && !strcmp(stdout_name, "vidconsole") &&
 	    IS_ENABLED(CONFIG_DM_VIDEO)) {
@@ -235,9 +236,21 @@ static void query_console_size(void)
 		rows = priv->rows;
 		cols = priv->cols;
 	} else if (query_console_serial(&rows, &cols)) {
-		return;
+		rows = 25;
+		cols = 80;
 	}
 
+	value = env_get("LINES");
+	if (value)
+		rows = simple_strtoul(value, NULL, 10);
+	value = env_get("COLUMNS");
+	if (value)
+		cols = simple_strtoul(value, NULL, 10);
+	if (rows <= 0)
+		rows = 25;
+	if (cols <= 0)
+		cols = 80;
+
 	/* Test if we can have Mode 1 */
 	if (cols >= 80 && rows >= 50) {
 		efi_cout_modes[1].present = 1;
-- 
2.18.0