Input: mt6779-keypad - fix hw code logic and row/col selection

Input: mt6779-keypad - fix hw code logic and row/col selection

This serie is the first follow-up on the mt6779-keypad in order to enable it on the MediaTek mt8183-pumpkin board.

To fully enable it on mt8183-pumpkin, we still need:
* double key support
* dts changes

To ease up reviewing, I preferred sending this first.

The first patch fixes a logic bug based on the (non-public) datasheet I have.
The second patch configures the keypad correctly in order to not report bogus values.

Thank you,
Mattijs

Changes in v3:
* reworked row/column logic as discussed in [1]
* Dropped Angelo's review since patch 1 changed

Changes in v2:
* Simplified SEL_COL/ROW_MASK macros as suggested by Dmitry
* Added Angelo's Reviewed-by on patch 1

Mattijs Korpershoek (2):
Input: mt6779-keypad - match hardware matrix organization
Input: mt6779-keypad - implement row/column selection

 drivers/input/keyboard/mt6779-keypad.c | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

[1] https://lore.kernel.org/r/YpMDZORAlHmg/x/[email protected]

base-commit: c4bcc1b99b8b8acdfe673e4701a9c2acb6b8b2fb

2.34.1

The MediaTek keypad has a set of bits representing keys, from KEY0 to KEY77, arranged in 5 chunks of 15 bits split into 5 32-bit registers.

In our implementation, we simply decided to use register number as row and offset in the register as column when encoding our "matrix".

Because of this, we can have a 5x32 matrix which does not match the hardware at all, which is confusing.

Change the row/column calculation to match the hardware.

---
 drivers/input/keyboard/mt6779-keypad.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

index 2e7c9187c10f..bd86cb95bde3 100644
@@ -42,7 +42,7 @@ static irqreturn_t mt6779_keypad_irq_handler(int irq, void *dev_id)
 	const unsigned short *keycode = keypad->input_dev->keycode;
 	DECLARE_BITMAP(new_state, MTK_KPD_NUM_BITS);
 	DECLARE_BITMAP(change, MTK_KPD_NUM_BITS);
-	unsigned int bit_nr;
+	unsigned int bit_nr, key;
 	unsigned int row, col;
 	unsigned int scancode;
 	unsigned int row_shift = get_count_order(keypad->n_cols);

@@ -61,8 +61,10 @@ static irqreturn_t mt6779_keypad_irq_handler(int irq, void *dev_id)
 		if (bit_nr % 32 >= 16)
 			continue;
 
-		row = bit_nr / 32;
-		col = bit_nr % 32;
+		key = bit_nr / 32 * 16 + bit_nr % 32;
+		row = key / 9;
+		col = key % 9;
+
 		scancode = MATRIX_SCAN_CODE(row, col, row_shift);
 		/* 1: not pressed, 0: pressed */
 		pressed = !test_bit(bit_nr, new_state);

2.34.1

The MediaTek keypad has a total of 6 input rows and 6 input columns. By default, rows/columns 0-2 are enabled.

This is controlled by the KP_SEL register:
- bits[9:4] control row selection
- bits[15:10] control column selection

Each bit enables the corresponding row/column number (e.g KP_SEL[4] enables ROW0)

Depending on how the keypad is wired, this may result in wrong readings of the keypad state.

Program the KP_SEL register to limit the key detection to n_rows, n_cols we retrieve from the device tree.

---
 drivers/input/keyboard/mt6779-keypad.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

index bd86cb95bde3..bf447bf598fb 100644
@@ -17,6 +17,11 @@
 #define MTK_KPD_DEBOUNCE	0x0018
 #define MTK_KPD_DEBOUNCE_MASK	GENMASK(13, 0)
 #define MTK_KPD_DEBOUNCE_MAX_MS	256
+#define MTK_KPD_SEL		0x0020
+#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)
+#define MTK_KPD_SEL_ROWMASK(r)	GENMASK((r) + 3, 4)
 #define MTK_KPD_NUM_MEMS	5
 #define MTK_KPD_NUM_BITS	136	/* 4*32+8 MEM5 only use 8 BITS */
 

@@ -161,6 +166,11 @@ static int mt6779_keypad_pdrv_probe(struct platform_device *pdev)
 	regmap_write(keypad->regmap, MTK_KPD_DEBOUNCE,
 		     (debounce * (1 << 5)) & MTK_KPD_DEBOUNCE_MASK);
 
+	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,
+			   MTK_KPD_SEL_COLMASK(keypad->n_cols));
+
 	keypad->clk = devm_clk_get(&pdev->dev, "kpd");
 	if (IS_ERR(keypad->clk))
 		return PTR_ERR(keypad->clk);

2.34.1

Applied the series, thank you.

Dmitry