This patch concerns GRUB as a coreboot payload, on x86. It does this:
retain current behaviour for non-coreboot targets, but force scancode
set 2 (AT) with translation (treat as XT) in GRUB, whereas GRUB
presently tries doing set 2 untranslated, before trying set 1.
On Dell Latitude E6400 this is problematic because the EC which
emulates the keyboard controller, reports scan set 2 with translation
so all seems well in code, but it only actually outputs set 1; however,
GRUB detects otherwise and then does set 2, translated. This resulted
in messed up key input.
It fixes keyboards in GRUB on Dell Latitude E6400/E6430. Nicholas Chin
told me the EC which emulates a keyboard controller, reports scancode
set 2 (AT, not XT) with translation (treat as XT), but only outputs set
1 even when changing it; 2+translate is standard. On other boards,
changing it works. It's an EC bug on Dell Latitude E6400.
GRUB does untranslated set 2 so keys were screwed. The fix forces
2+translation on coreboot.
Tested and works perfectly. This diff is taken from my work on top of
GRUB rev e58b870ff926415e23fc386af41ff81b2f588763 but it should apply
in latest commits from GRUB master branch.
PS: This also fixes Dell Latitude E6430.
--
Leah Rowe <l...@libreboot.org>
>From 96c0bbe5d406b616360a7fce7cee67d7692c0d6d Mon Sep 17 00:00:00 2001
From: Leah Rowe <l...@libreboot.org>
Date: Mon, 30 Oct 2023 22:19:21 +0000
Subject: [PATCH 1/1] at_keyboard coreboot: force scancodes2+translate
Scan code set 2 with translation should be assumed in
every case, as the default starting position.
However, GRUB is trying to detect and use other modes
such as set 2 without translation, or set 1 without
translation from set 2; it also detects no-mode and
assumes mode 1, on really old keyboards.
The current behaviour has been retained, for everything
except GRUB_MACHINE_COREBOOT; for the latter, scan code
set 2 with translation is hardcoded, and forced in code.
This is required to make keyboard initialisation work on
the MEC5035 EC used by the Dell Latitude E6400, when
running GRUB as a coreboot payload on that laptop. The
EC reports scancode set 2 with translation when probed,
but actually only outputs scancode set 1.
Since GRUB is attempting to use it without translation,
and since the machine reports set 2 with translation,
but only ever outputs set 1 scancodes, this results in
wrong keypresses for every key.
This fix fixed that, by forcing set 2 with translation,
treating it as set 1, but only on coreboot. This is the
same behaviour used in GNU+Linux systems and SeaBIOS.
With this change, GRUB keyboard initialisation now works
just fine on those machines.
This has *also* been tested on other coreboot machines
running GRUB; several HP EliteBooks, ThinkPads and
Dell Precision T1650. All seems to work just fine.
Signed-off-by: Leah Rowe <l...@libreboot.org>
---
grub-core/term/at_keyboard.c | 20 ++++++++++++++++++--
1 file changed, 18 insertions(+), 2 deletions(-)
diff --git a/grub-core/term/at_keyboard.c b/grub-core/term/at_keyboard.c
index f8a129eb7..8207225c2 100644
--- a/grub-core/term/at_keyboard.c
+++ b/grub-core/term/at_keyboard.c
@@ -138,6 +138,7 @@ write_mode (int mode)
return (i != GRUB_AT_TRIES);
}
+#if !defined (GRUB_MACHINE_COREBOOT)
static int
query_mode (void)
{
@@ -161,10 +162,12 @@ query_mode (void)
return 3;
return 0;
}
+#endif
static void
set_scancodes (void)
{
+#if !defined (GRUB_MACHINE_COREBOOT)
/* You must have visited computer museum. Keyboard without scancode set
knowledge. Assume XT. */
if (!grub_keyboard_orig_set)
@@ -173,20 +176,33 @@ set_scancodes (void)
ps2_state.current_set = 1;
return;
}
+#endif
#if !USE_SCANCODE_SET
ps2_state.current_set = 1;
return;
-#else
+#endif
+#if defined (GRUB_MACHINE_COREBOOT)
+ /* enable translation */
+ grub_keyboard_controller_write (grub_keyboard_controller_orig
+ & ~KEYBOARD_AT_DISABLE);
+#else
+ /* if not coreboot, disable translation and try mode 2 first, before 1 */
grub_keyboard_controller_write (grub_keyboard_controller_orig
& ~KEYBOARD_AT_TRANSLATE
& ~KEYBOARD_AT_DISABLE);
+#endif
keyboard_controller_wait_until_ready ();
grub_outb (KEYBOARD_COMMAND_ENABLE, KEYBOARD_REG_DATA);
-
write_mode (2);
+
+#if defined (GRUB_MACHINE_COREBOOT)
+ /* mode 2 with translation, so make grub treat as set 1 */
+ ps2_state.current_set = 1;
+#else
+ /* if not coreboot, translation isn't set; test 2 and fall back to 1 */
ps2_state.current_set = query_mode ();
grub_dprintf ("atkeyb", "returned set %d\n", ps2_state.current_set);
if (ps2_state.current_set == 2)
--
2.39.2
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