[coreboot-gerrit] Change in coreboot[master]: libpayload: keyboard: Ignore special keys

[Thejaswani Putta (Code Review)]

Hello Thejaswani Putta,

I'd like you to do a code review. Please visit

https://review.coreboot.org/c/coreboot/+/36654

to review the following change.

Change subject: libpayload: keyboard: Ignore special keys
......................................................................

libpayload: keyboard: Ignore special keys

some special keys emit a prefix scan code 0xE0, we will ignore all
these except for the power button, F12 and cursor keys.

These changes are enabled with a config flag in libpayload and by default
it is disabled, whichever board needs it will enable it in its Kconfig.

BUG:b:139511038
TEST=boot in recovery mode, press F12 to go to diagnostic mode and power
button to confirm. Also in recovery mode left arrow, right arrow, up arrow,
down arrow changes the language on the firmware screen.

Change-Id: I1c11939d18391bebe53ca21cf33a096ba369cd56
Signed-off-by: Thejaswani Putta 
---
M payloads/libpayload/Kconfig
M payloads/libpayload/drivers/i8042/keyboard.c
2 files changed, 44 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/54/36654/1

diff --git a/payloads/libpayload/Kconfig b/payloads/libpayload/Kconfig
index 97b970b..16e4c3a 100644
--- a/payloads/libpayload/Kconfig
+++ b/payloads/libpayload/Kconfig
@@ -353,6 +353,10 @@
    bool "Ignore keyboard failures during init and always add input device"
    default n

+config PC_KEYBOARD_TREAT_MEDIA_KEYS_AS_FN
+	bool "Donot ignore prefix scan code OXE0 for some special keys"
+	default n
+
 config PC_KEYBOARD_LAYOUT_US
    bool "English (US) keyboard layout"
    depends on PC_KEYBOARD
diff --git a/payloads/libpayload/drivers/i8042/keyboard.c b/payloads/libpayload/drivers/i8042/keyboard.c
index 48d35a0..e079a96 100644
--- a/payloads/libpayload/drivers/i8042/keyboard.c
+++ b/payloads/libpayload/drivers/i8042/keyboard.c
@@ -230,6 +230,40 @@
    return modifier;
 }

+/* Ignore almost all special function keys & get the next key */
+/* F12 key generates 0xe0 0xb on press when fn is engaged. */
+static int keyboard_media_keys(void)
+{
+	unsigned char ch;
+	int ret = 0;
+
+	ch = keyboard_get_scancode();
+	switch (ch) {
+	case 0xb:
+		ret = KEY_F(12);
+		break;
+	case 0x5e:
+		ret = POWER_BUTTON;
+		break;
+	case 0x4b:
+		ret = KEY_LEFT;
+		break;
+	case 0x4d:
+		ret = KEY_RIGHT;
+		break;
+	case 0x48:
+		ret = KEY_UP;
+		break;
+	case 0x50:
+		ret = KEY_DOWN;
+		break;
+	default:
+		ret = 0;
+	}
+	printf("Teja: Returning %x \n", ret);
+	return ret;
+}
+
 int keyboard_getchar(void)
 {
    unsigned char ch;
@@ -240,6 +274,12 @@

ch = keyboard_get_scancode();

+	/* process media keys, only return the keys that are needed */
+	if (IS_ENABLED(CONFIG_LP_PC_KEYBOARD_TREAT_MEDIA_KEYS_AS_FN)) {
+		if (ch == 0xe0) {
+			return keyboard_media_keys();
+		}		
+	}
    if (!(ch & 0x80) && ch < 0x59) {
    	shift =
    	    (modifier & KB_MOD_SHIFT) ^ (modifier & KB_MOD_CAPSLOCK) ? 1 : 0;