[PATCH v1 4/6] Input: mt6779-keypad - support double keys matrix

[Mattijs Korpershoek <mkorpershoek@baylibre.com>]

MediaTek keypad has 2 modes of detecting key events:
- single key: each (row, column) can detect one key
- double key: each (row, column) is a group of 2 keys

Double key support exists to minimize cost, since it reduces the number
of pins required for physical keys.

Double key is configured by setting BIT(0) of the KP_SEL register.

Enable double key matrix support based on the mediatek,double-keys
device tree property.

Signed-off-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>

diff --git a/drivers/input/keyboard/mt6779-keypad.c b/drivers/input/keyboard/mt6779-keypad.c
index bf447bf598fb..9a5dbd415dac 100644
--- a/drivers/input/keyboard/mt6779-keypad.c
+++ b/drivers/input/keyboard/mt6779-keypad.c
@@ -18,6 +18,7 @@
 #define MTK_KPD_DEBOUNCE_MASK	GENMASK(13, 0)
 #define MTK_KPD_DEBOUNCE_MAX_MS	256
 #define MTK_KPD_SEL		0x0020
+#define MTK_KPD_SEL_DOUBLE_KP_MODE	BIT(0)
 #define MTK_KPD_SEL_COL	GENMASK(15, 10)
 #define MTK_KPD_SEL_ROW	GENMASK(9, 4)
 #define MTK_KPD_SEL_COLMASK(c)	GENMASK((c) + 9, 10)
@@ -31,6 +32,7 @@ struct mt6779_keypad {
 	struct clk *clk;
 	u32 n_rows;
 	u32 n_cols;
+	bool double_keys;
 	DECLARE_BITMAP(keymap_state, MTK_KPD_NUM_BITS);
 };
 
@@ -67,8 +69,13 @@ static irqreturn_t mt6779_keypad_irq_handler(int irq, void *dev_id)
 			continue;
 
 		key = bit_nr / 32 * 16 + bit_nr % 32;
-		row = key / 9;
-		col = key % 9;
+		if (keypad->double_keys) {
+			row = key / 13;
+			col = (key % 13) / 2;
+		} else {
+			row = key / 9;
+			col = key % 9;
+		}
 
 		scancode = MATRIX_SCAN_CODE(row, col, row_shift);
 		/* 1: not pressed, 0: pressed */
@@ -150,6 +157,8 @@ static int mt6779_keypad_pdrv_probe(struct platform_device *pdev)
 
 	wakeup = device_property_read_bool(&pdev->dev, "wakeup-source");
 
+	keypad->double_keys = device_property_read_bool(&pdev->dev, "mediatek,double-keys");
+
 	dev_dbg(&pdev->dev, "n_row=%d n_col=%d debounce=%d\n",
 		keypad->n_rows, keypad->n_cols, debounce);
 
@@ -166,6 +175,10 @@ static int mt6779_keypad_pdrv_probe(struct platform_device *pdev)
 	regmap_write(keypad->regmap, MTK_KPD_DEBOUNCE,
 		     (debounce * (1 << 5)) & MTK_KPD_DEBOUNCE_MASK);
 
+	if (keypad->double_keys)
+		regmap_update_bits(keypad->regmap, MTK_KPD_SEL,
+				   MTK_KPD_SEL_DOUBLE_KP_MODE, MTK_KPD_SEL_DOUBLE_KP_MODE);
+
 	regmap_update_bits(keypad->regmap, MTK_KPD_SEL, MTK_KPD_SEL_ROW,
 			   MTK_KPD_SEL_ROWMASK(keypad->n_rows));
 	regmap_update_bits(keypad->regmap, MTK_KPD_SEL, MTK_KPD_SEL_COL,

-- 
b4 0.10.0-dev-54fef