[PATCH 2/4] ALSA: caiaq: Fix the Kore controller key map

[Niko Huuskonen <niko.huuskonen.00@gmail.com>]

keycode_kore does not match the hardware in two places:

- Softkeys 5 to 8 are listed in reverse order, so pressing the fifth
  softkey reports BTN_8, the sixth BTN_7 and so on. Softkeys 1 to 4 are
  correct. The OpenKoreBridge project, which drives a Kore 2 through
  this driver, works around the same reversal in userspace.

- On the first Kore controller the touch sensors of the eight knobs are
  scrambled: touching knob 1 reports KEY_BRL_DOT6, knob 2 KEY_BRL_DOT8,
  knob 3 KEY_BRL_DOT2, knob 6 KEY_BRL_DOT7, knob 7 KEY_BRL_DOT1 and
  knob 8 KEY_BRL_DOT3. Only knobs 4 and 5 are right.

Put the softkeys in order for both controllers, and give the first Kore
controller its own touch sensor order, so that BTN_n and KEY_BRL_DOTn
belong to the n-th knob. The touch sensor order of the Kore 2 is left
alone, as it could not be checked.

Userspace that compensates for the old order needs to follow. It can
read the key map with EVIOCGKEYCODE, which also makes it possible to
support kernels with and without this change.

Tested on a Kore controller (USB ID 17cc:4711).

Link: https://github.com/OpenKoreBridge/OpenKoreBridge
Fixes: 8e3cd08ed8e5 ("[ALSA] caiaq - add control API and more input features")
Assisted-by: LLM
Signed-off-by: Niko Huuskonen <niko.huuskonen.00@gmail.com>
---
 sound/usb/caiaq/input.c | 29 +++++++++++++++++++++++++----
 1 file changed, 25 insertions(+), 4 deletions(-)

diff --git a/sound/usb/caiaq/input.c b/sound/usb/caiaq/input.c
index 8d924330c54c..856235c3398e 100644
--- a/sound/usb/caiaq/input.c
+++ b/sound/usb/caiaq/input.c
@@ -41,11 +41,11 @@ static const unsigned short keycode_kore[] = {
 	BTN_3,
 	BTN_2,
 	BTN_1,
-	BTN_8,
-	BTN_7,
-	BTN_6,
 	BTN_5,
-	KEY_BRL_DOT4,   /* touch sensitive knobs */
+	BTN_6,
+	BTN_7,
+	BTN_8,
+	KEY_BRL_DOT4,   /* touch sensitive knobs (Kore 2 order) */
 	KEY_BRL_DOT3,
 	KEY_BRL_DOT2,
 	KEY_BRL_DOT1,
@@ -55,6 +55,21 @@ static const unsigned short keycode_kore[] = {
 	KEY_BRL_DOT5
 };
 
+/* index of the first touch sensor in keycode_kore */
+#define KORE_TOUCH_KEYS	24
+
+/* the first Kore controller reports its touch sensors in this order */
+static const unsigned short keycode_kore1_touch[] = {
+	KEY_BRL_DOT4,
+	KEY_BRL_DOT8,
+	KEY_BRL_DOT3,
+	KEY_BRL_DOT7,
+	KEY_BRL_DOT2,
+	KEY_BRL_DOT6,
+	KEY_BRL_DOT1,
+	KEY_BRL_DOT5
+};
+
 #define MASCHINE_BUTTONS   (42)
 #define MASCHINE_BUTTON(X) ((X) + BTN_MISC)
 #define MASCHINE_PADS      (16)
@@ -666,6 +681,12 @@ int snd_usb_caiaq_input_init(struct snd_usb_caiaqdev *cdev)
 		input->absbit[BIT_WORD(ABS_MISC)] |= BIT_MASK(ABS_MISC);
 		BUILD_BUG_ON(sizeof(cdev->keycode) < sizeof(keycode_kore));
 		memcpy(cdev->keycode, keycode_kore, sizeof(keycode_kore));
+		BUILD_BUG_ON(KORE_TOUCH_KEYS + ARRAY_SIZE(keycode_kore1_touch) >
+			     ARRAY_SIZE(keycode_kore));
+		if (cdev->chip.usb_id ==
+		    USB_ID(USB_VID_NATIVEINSTRUMENTS, USB_PID_KORECONTROLLER))
+			memcpy(cdev->keycode + KORE_TOUCH_KEYS, keycode_kore1_touch,
+			       sizeof(keycode_kore1_touch));
 		input->keycodemax = ARRAY_SIZE(keycode_kore);
 		input_set_abs_params(input, ABS_HAT0X, 0, 999, 0, 10);
 		input_set_abs_params(input, ABS_HAT0Y, 0, 999, 0, 10);
-- 
2.55.0