[PATCH v18] Add matrix keypad driver support for Mediatek SoCs

[PATCH v18] Add matrix keypad driver support for Mediatek SoCs

[Fengping Yu]

Change since v17:
- modify how to get keycode in keypad interrupt handler
- replace variable ret as error in probe function
- update keypad, num-columns and keypad, num-rows description in binding documentation

fengping.yu (3):
  dt-bindings: Add bindings for Mediatek matrix keypad
  drivers: input:keyboard: Add mtk keypad driver
  configs: defconfig: Add CONFIG_KEYBOARD_MTK_KPD=m

 .../devicetree/bindings/input/mtk-kpd.yaml    |  83 +++++++
 arch/arm64/configs/defconfig                  |   1 +
 drivers/input/keyboard/Kconfig                |  11 +
 drivers/input/keyboard/Makefile               |   1 +
 drivers/input/keyboard/mtk-kpd.c              | 218 ++++++++++++++++++
 5 files changed, 314 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/input/mtk-kpd.yaml
 create mode 100644 drivers/input/keyboard/mtk-kpd.c

--
2.18.0

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[PATCH v18 1/3] dt-bindings: Add bindings for Mediatek matrix keypad

[Fengping Yu]

From: "fengping.yu" <fengping.yu@mediatek.com>

This patch add devicetree bindings for Mediatek matrix keypad driver.

Signed-off-by: fengping.yu <fengping.yu@mediatek.com>
---
 .../devicetree/bindings/input/mtk-kpd.yaml    | 83 +++++++++++++++++++
 1 file changed, 83 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/input/mtk-kpd.yaml

diff --git a/Documentation/devicetree/bindings/input/mtk-kpd.yaml b/Documentation/devicetree/bindings/input/mtk-kpd.yaml
new file mode 100644
index 000000000000..eda2c6efbfbf
--- /dev/null
+++ b/Documentation/devicetree/bindings/input/mtk-kpd.yaml
@@ -0,0 +1,83 @@
+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+version: 1
+
+$id: http://devicetree.org/schemas/input/mtk-keypad.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Mediatek's Keypad Controller device tree bindings
+
+maintainer:
+  - Fengping Yu <fengping.yu@mediatek.com>
+
+description: |
+  Mediatek's Keypad controller is used to interface a SoC with a matrix-type
+  keypad device. The keypad controller supports multiple row and column lines.
+  A key can be placed at each intersection of a unique row and a unique column.
+  The keypad controller can sense a key-press and key-release and report the
+  event using a interrupt to the cpu.
+
+properties:
+  compatible:
+    oneOf:
+      - const: "mediatek,mt6779-keypad"
+      - const: "mediatek,mt6873-keypad"
+
+  clock-names:
+    description: Names of the clocks listed in clocks property in the same order
+    maxItems: 1
+    items:
+    	- const: kpd
+
+  clocks:
+    description: Must contain one entry, for the module clock
+    refs: devicetree/bindings/clocks/clock-bindings.txt for details.
+
+  interrupts:
+    description: A single interrupt specifier
+    maxItems: 1
+
+  linux,keymap:
+    description: The keymap for keys as described in the binding document
+    refs: devicetree/bindings/input/matrix-keymap.txt
+    minItems: 1
+
+  reg:
+    description: The base address of the Keypad register bank
+    maxItems: 1
+
+  wakeup-source:
+    description: use any event on keypad as wakeup event
+    type: boolean
+
+  keypad,num-columns:
+    description: Number of column lines connected to the keypad controller.
+
+  keypad,num-rows:
+    description: Number of row lines connected to the keypad controller.
+
+  mediatek,debounce-us:
+    description: Debounce interval in microseconds, if not specified, the default
+    value is 16000
+    maximum: 256000
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - linux,keymap
+  - clocks
+  - clock-names
+
+examples:
+  - |
+
+  kp@10010000 {
+    compatible = "mediatek,kp";
+    reg = <0 0x10010000 0 0x1000>;
+    linux,keymap = < MATRIX_KEY(0x00, 0x00, KEY_VOLUMEDOWN) >;
+    interrupts = <GIC_SPI 75 IRQ_TYPE_EDGE_FALLING>;
+    clocks = <&clk26m>;
+    clock-names = "kpd";
+  };
-- 
2.18.0
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Re: [PATCH v18 1/3] dt-bindings: Add bindings for Mediatek matrix keypad

[Dmitry Torokhov]

Hi Rob,

On Wed, Sep 09, 2020 at 03:21:58PM +0800, Fengping Yu wrote:
> From: "fengping.yu" <fengping.yu@mediatek.com>
> 
> This patch add devicetree bindings for Mediatek matrix keypad driver.

I am generally happy with the driver itself, do you have any concerns
with the binding?

Thanks!

> 
> Signed-off-by: fengping.yu <fengping.yu@mediatek.com>
> ---
>  .../devicetree/bindings/input/mtk-kpd.yaml    | 83 +++++++++++++++++++
>  1 file changed, 83 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/input/mtk-kpd.yaml
> 
> diff --git a/Documentation/devicetree/bindings/input/mtk-kpd.yaml b/Documentation/devicetree/bindings/input/mtk-kpd.yaml
> new file mode 100644
> index 000000000000..eda2c6efbfbf
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/input/mtk-kpd.yaml
> @@ -0,0 +1,83 @@
> +# SPDX-License-Identifier: GPL-2.0
> +%YAML 1.2
> +---
> +version: 1
> +
> +$id: http://devicetree.org/schemas/input/mtk-keypad.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Mediatek's Keypad Controller device tree bindings
> +
> +maintainer:
> +  - Fengping Yu <fengping.yu@mediatek.com>
> +
> +description: |
> +  Mediatek's Keypad controller is used to interface a SoC with a matrix-type
> +  keypad device. The keypad controller supports multiple row and column lines.
> +  A key can be placed at each intersection of a unique row and a unique column.
> +  The keypad controller can sense a key-press and key-release and report the
> +  event using a interrupt to the cpu.
> +
> +properties:
> +  compatible:
> +    oneOf:
> +      - const: "mediatek,mt6779-keypad"
> +      - const: "mediatek,mt6873-keypad"
> +
> +  clock-names:
> +    description: Names of the clocks listed in clocks property in the same order
> +    maxItems: 1
> +    items:
> +    	- const: kpd
> +
> +  clocks:
> +    description: Must contain one entry, for the module clock
> +    refs: devicetree/bindings/clocks/clock-bindings.txt for details.
> +
> +  interrupts:
> +    description: A single interrupt specifier
> +    maxItems: 1
> +
> +  linux,keymap:
> +    description: The keymap for keys as described in the binding document
> +    refs: devicetree/bindings/input/matrix-keymap.txt
> +    minItems: 1
> +
> +  reg:
> +    description: The base address of the Keypad register bank
> +    maxItems: 1
> +
> +  wakeup-source:
> +    description: use any event on keypad as wakeup event
> +    type: boolean
> +
> +  keypad,num-columns:
> +    description: Number of column lines connected to the keypad controller.
> +
> +  keypad,num-rows:
> +    description: Number of row lines connected to the keypad controller.
> +
> +  mediatek,debounce-us:
> +    description: Debounce interval in microseconds, if not specified, the default
> +    value is 16000
> +    maximum: 256000
> +
> +required:
> +  - compatible
> +  - reg
> +  - interrupts
> +  - linux,keymap
> +  - clocks
> +  - clock-names
> +
> +examples:
> +  - |
> +
> +  kp@10010000 {
> +    compatible = "mediatek,kp";
> +    reg = <0 0x10010000 0 0x1000>;
> +    linux,keymap = < MATRIX_KEY(0x00, 0x00, KEY_VOLUMEDOWN) >;
> +    interrupts = <GIC_SPI 75 IRQ_TYPE_EDGE_FALLING>;
> +    clocks = <&clk26m>;
> +    clock-names = "kpd";
> +  };
> -- 
> 2.18.0

-- 
Dmitry

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[PATCH v18 2/3] drivers: input:keyboard: Add mtk keypad driver

[Fengping Yu]

From: "fengping.yu" <fengping.yu@mediatek.com>

This patch adds matrix keypad support for Mediatek SoCs.

Signed-off-by: fengping.yu <fengping.yu@mediatek.com>
Reviewed-by: Marco Felsch <m.felsch@pengutronix.de>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
---
 drivers/input/keyboard/Kconfig   |  11 ++
 drivers/input/keyboard/Makefile  |   1 +
 drivers/input/keyboard/mtk-kpd.c | 218 +++++++++++++++++++++++++++++++
 3 files changed, 230 insertions(+)
 create mode 100644 drivers/input/keyboard/mtk-kpd.c

diff --git a/drivers/input/keyboard/Kconfig b/drivers/input/keyboard/Kconfig
index 793ecbbda32c..1ee845c292c6 100644
--- a/drivers/input/keyboard/Kconfig
+++ b/drivers/input/keyboard/Kconfig
@@ -782,6 +782,17 @@ config KEYBOARD_BCM
 	  To compile this driver as a module, choose M here: the
 	  module will be called bcm-keypad.
 
+config KEYBOARD_MTK_KPD
+	tristate "MediaTek Keypad Support"
+	depends on ARCH_MEDIATEK || COMPILE_TEST
+	select REGMAP_MMIO
+	select INPUT_MATRIXKMAP
+	help
+	  Say Y here if you want to use the keypad on MediaTek SoCs.
+	  If unsure, say N.
+	  To compile this driver as a module, choose M here: the
+	  module will be called mtk-kpd.
+
 config KEYBOARD_MTK_PMIC
 	tristate "MediaTek PMIC keys support"
 	depends on MFD_MT6397
diff --git a/drivers/input/keyboard/Makefile b/drivers/input/keyboard/Makefile
index 1d689fdd5c00..6c9d852c377e 100644
--- a/drivers/input/keyboard/Makefile
+++ b/drivers/input/keyboard/Makefile
@@ -43,6 +43,7 @@ obj-$(CONFIG_KEYBOARD_MATRIX)		+= matrix_keypad.o
 obj-$(CONFIG_KEYBOARD_MAX7359)		+= max7359_keypad.o
 obj-$(CONFIG_KEYBOARD_MCS)		+= mcs_touchkey.o
 obj-$(CONFIG_KEYBOARD_MPR121)		+= mpr121_touchkey.o
+obj-$(CONFIG_KEYBOARD_MTK_KPD)		+= mtk-kpd.o
 obj-$(CONFIG_KEYBOARD_MTK_PMIC) 	+= mtk-pmic-keys.o
 obj-$(CONFIG_KEYBOARD_NEWTON)		+= newtonkbd.o
 obj-$(CONFIG_KEYBOARD_NOMADIK)		+= nomadik-ske-keypad.o
diff --git a/drivers/input/keyboard/mtk-kpd.c b/drivers/input/keyboard/mtk-kpd.c
new file mode 100644
index 000000000000..e5254beee163
--- /dev/null
+++ b/drivers/input/keyboard/mtk-kpd.c
@@ -0,0 +1,218 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 MediaTek Inc.
+ * Author Fengping Yu <fengping.yu@mediatek.com>
+ */
+#include <linux/bitops.h>
+#include <linux/clk.h>
+#include <linux/input/matrix_keypad.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/property.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+#define MTK_KPD_NAME		"mtk-kpd"
+#define MTK_KPD_MEM		0x0004
+#define MTK_KPD_DEBOUNCE	0x0018
+#define MTK_KPD_DEBOUNCE_MASK	GENMASK(13, 0)
+#define MTK_KPD_DEBOUNCE_MAX_US	256000
+#define MTK_KPD_NUM_MEMS	5
+#define MTK_KPD_NUM_BITS	136	/* 4*32+8 MEM5 only use 8 BITS */
+
+struct mtk_keypad {
+	struct regmap *regmap;
+	struct input_dev *input_dev;
+	struct clk *clk;
+	void __iomem *base;
+	u32 n_rows;
+	u32 n_cols;
+	DECLARE_BITMAP(keymap_state, MTK_KPD_NUM_BITS);
+};
+
+static const struct regmap_config keypad_regmap_cfg = {
+	.reg_bits = 32,
+	.val_bits = 32,
+	.reg_stride = sizeof(u32),
+	.max_register = 36,
+};
+
+static irqreturn_t kpd_irq_handler(int irq, void *dev_id)
+{
+	struct mtk_keypad *keypad = dev_id;
+	unsigned short *keycode = keypad->input_dev->keycode;
+	DECLARE_BITMAP(new_state, MTK_KPD_NUM_BITS);
+	DECLARE_BITMAP(change, MTK_KPD_NUM_BITS);
+	int bit_nr;
+	int pressed;
+	unsigned short code;
+	int row, col;
+	int row_shift = get_count_order(keypad->n_cols);
+
+	regmap_bulk_read(keypad->regmap, MTK_KPD_MEM,
+			 new_state, MTK_KPD_NUM_MEMS);
+
+	bitmap_xor(change, new_state, keypad->keymap_state, MTK_KPD_NUM_BITS);
+
+	for_each_set_bit(bit_nr, change, MTK_KPD_NUM_BITS) {
+	/* For 32bits register, only bits [15:0] use to indicate key status */
+		if (bit_nr % 32 >= 16)
+			continue;
+
+		/* 1: not pressed, 0: pressed */
+		pressed = !test_bit(bit_nr, new_state);
+		dev_dbg(&keypad->input_dev->dev, "%s",
+			pressed ? "pressed" : "released");
+
+		row = bit_nr / 32;
+		col = bit_nr % 32;
+
+		code = keycode[MATRIX_SCAN_CODE(row, col, row_shift)];
+
+		input_report_key(keypad->input_dev, code, pressed);
+		input_sync(keypad->input_dev);
+
+		dev_dbg(&keypad->input_dev->dev,
+			"report Linux keycode = %d\n", code);
+	}
+
+	bitmap_copy(keypad->keymap_state, new_state, MTK_KPD_NUM_BITS);
+
+	return IRQ_HANDLED;
+}
+
+static void kpd_clk_disable(void *data)
+{
+	clk_disable_unprepare(data);
+}
+
+static int kpd_pdrv_probe(struct platform_device *pdev)
+{
+	struct mtk_keypad *keypad;
+	unsigned int irq;
+	u32 debounce;
+	bool wakeup;
+	int error;
+
+	keypad = devm_kzalloc(&pdev->dev, sizeof(*keypad), GFP_KERNEL);
+	if (!keypad)
+		return -ENOMEM;
+
+	keypad->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(keypad->base))
+		return PTR_ERR(keypad->base);
+
+	keypad->regmap = devm_regmap_init_mmio(&pdev->dev,
+					       keypad->base,
+					       &keypad_regmap_cfg);
+	if (IS_ERR(keypad->regmap)) {
+		dev_err(&pdev->dev,
+			"regmap init failed:%pe\n", keypad->regmap);
+		return PTR_ERR(keypad->regmap);
+	}
+
+	bitmap_fill(keypad->keymap_state, MTK_KPD_NUM_BITS);
+
+	keypad->input_dev = devm_input_allocate_device(&pdev->dev);
+	if (!keypad->input_dev) {
+		dev_err(&pdev->dev, "Failed to allocate input dev\n");
+		return -ENOMEM;
+	}
+
+	keypad->input_dev->name = MTK_KPD_NAME;
+	keypad->input_dev->id.bustype = BUS_HOST;
+
+	error = matrix_keypad_parse_properties(&pdev->dev, &keypad->n_rows,
+					       &keypad->n_cols);
+	if (error) {
+		dev_err(&pdev->dev, "Failed to parse keypad params\n");
+		return error;
+	}
+
+	if (device_property_read_u32(&pdev->dev, "mediatek,debounce-us",
+				     &debounce))
+		debounce = 16000;
+
+	if (debounce > MTK_KPD_DEBOUNCE_MAX_US) {
+		dev_err(&pdev->dev, "Debounce time exceeds the maximum allowed time %dus\n",
+			MTK_KPD_DEBOUNCE_MAX_US);
+		return -EINVAL;
+	}
+
+	wakeup = device_property_read_bool(&pdev->dev, "wakeup-source");
+
+	dev_dbg(&pdev->dev, "n_row=%d n_col=%d debounce=%d\n",
+		keypad->n_rows, keypad->n_cols, debounce);
+
+	error = matrix_keypad_build_keymap(NULL, NULL,
+					   keypad->n_rows,
+					   keypad->n_cols,
+					   NULL,
+					   keypad->input_dev);
+	if (error) {
+		dev_err(&pdev->dev, "Failed to build keymap\n");
+		return error;
+	}
+
+	regmap_write(keypad->regmap, MTK_KPD_DEBOUNCE,
+		     debounce * 32 / 1000 & MTK_KPD_DEBOUNCE_MASK);
+
+	keypad->clk = devm_clk_get(&pdev->dev, "kpd");
+	if (IS_ERR(keypad->clk))
+		return PTR_ERR(keypad->clk);
+
+	error = clk_prepare_enable(keypad->clk);
+	if (error) {
+		dev_err(&pdev->dev, "cannot prepare/enable keypad clock\n");
+		return error;
+	}
+
+	error = devm_add_action_or_reset(&pdev->dev, kpd_clk_disable, keypad->clk);
+	if (error)
+		return error;
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return irq;
+
+	error = devm_request_threaded_irq(&pdev->dev, irq,
+					  NULL, kpd_irq_handler,
+					  IRQF_ONESHOT,
+					  MTK_KPD_NAME, keypad);
+	if (error) {
+		dev_err(&pdev->dev, "Failed to request IRQ#%d:%d\n",
+			irq, error);
+		return error;
+	}
+
+	error = input_register_device(keypad->input_dev);
+	if (error) {
+		dev_err(&pdev->dev, "Failed to register device\n");
+		return error;
+	}
+
+	error =  device_init_wakeup(&pdev->dev, wakeup);
+	if (error)
+		dev_warn(&pdev->dev, "device_init_wakeup fail\n");
+
+	return 0;
+}
+
+static const struct of_device_id kpd_of_match[] = {
+	{ .compatible = "mediatek,mt6779-keypad" },
+	{ .compatible = "mediatek,mt6873-keypad" },
+	{ /* sentinel */ }
+};
+
+static struct platform_driver kpd_pdrv = {
+	.probe = kpd_pdrv_probe,
+	.driver = {
+		   .name = MTK_KPD_NAME,
+		   .of_match_table = kpd_of_match,
+	},
+};
+module_platform_driver(kpd_pdrv);
+
+MODULE_AUTHOR("Mediatek Corporation");
+MODULE_DESCRIPTION("MTK Keypad (KPD) Driver");
+MODULE_LICENSE("GPL");
-- 
2.18.0
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Re: [PATCH v18 2/3] drivers: input:keyboard: Add mtk keypad driver

[Dmitry Torokhov]

Hi Fengping,

On Wed, Sep 09, 2020 at 03:22:00PM +0800, Fengping Yu wrote:
> From: "fengping.yu" <fengping.yu@mediatek.com>
> 
> This patch adds matrix keypad support for Mediatek SoCs.

I am generally happy with the driver, however I do not believe this will
be the only Mediatek driver ever. Do you think we could rename it to
mt6779-keypad.c and use mt6779_keypad_ as prefix for function names?

Thanks!

-- 
Dmitry

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[PATCH v18 3/3] configs: defconfig: Add CONFIG_KEYBOARD_MTK_KPD=m

[Fengping Yu]

From: "fengping.yu" <fengping.yu@mediatek.com>

Add Mediatek matrix keypad support in defconfig.

Signed-off-by: fengping.yu <fengping.yu@mediatek.com>
Reviewed-by: Marco Felsch <m.felsch@pengutronix.de>
---
 arch/arm64/configs/defconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/configs/defconfig b/arch/arm64/configs/defconfig
index 883e8bace3ed..d96e7576f0e1 100644
--- a/arch/arm64/configs/defconfig
+++ b/arch/arm64/configs/defconfig
@@ -354,6 +354,7 @@ CONFIG_KEYBOARD_GPIO=y
 CONFIG_KEYBOARD_SNVS_PWRKEY=m
 CONFIG_KEYBOARD_IMX_SC_KEY=m
 CONFIG_KEYBOARD_CROS_EC=y
+CONFIG_KEYBOARD_MTK_KPD=m
 CONFIG_INPUT_TOUCHSCREEN=y
 CONFIG_TOUCHSCREEN_ATMEL_MXT=m
 CONFIG_INPUT_MISC=y
-- 
2.18.0
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[PATCH v18] Add matrix keypad driver support for Mediatek SoCs

[Fengping Yu]

Change since v17:
- modify how to get keycode in keypad isr function
- update keypad, num-columns and keypad, num-rows descriptions
- replace variable ret as error in probe function

fengping.yu (3):
  dt-bindings: Add bindings for Mediatek matrix keypad
  drivers: input:keyboard: Add mtk keypad driver
  configs: defconfig: Add CONFIG_KEYBOARD_MTK_KPD=m

 .../devicetree/bindings/input/mtk-kpd.yaml    |  83 +++++++
 arch/arm64/configs/defconfig                  |   1 +
 drivers/input/keyboard/Kconfig                |  11 +
 drivers/input/keyboard/Makefile               |   1 +
 drivers/input/keyboard/mtk-kpd.c              | 218 ++++++++++++++++++
 5 files changed, 314 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/input/mtk-kpd.yaml
 create mode 100644 drivers/input/keyboard/mtk-kpd.c

--
2.18.0

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[PATCH v18 1/3] dt-bindings: Add bindings for Mediatek matrix keypad

[Fengping Yu]

From: "fengping.yu" <fengping.yu@mediatek.com>

This patch add devicetree bindings for Mediatek matrix keypad driver.

Signed-off-by: fengping.yu <fengping.yu@mediatek.com>
---
 .../devicetree/bindings/input/mtk-kpd.yaml    | 83 +++++++++++++++++++
 1 file changed, 83 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/input/mtk-kpd.yaml

diff --git a/Documentation/devicetree/bindings/input/mtk-kpd.yaml b/Documentation/devicetree/bindings/input/mtk-kpd.yaml
new file mode 100644
index 000000000000..eda2c6efbfbf
--- /dev/null
+++ b/Documentation/devicetree/bindings/input/mtk-kpd.yaml
@@ -0,0 +1,83 @@
+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+version: 1
+
+$id: http://devicetree.org/schemas/input/mtk-keypad.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Mediatek's Keypad Controller device tree bindings
+
+maintainer:
+  - Fengping Yu <fengping.yu@mediatek.com>
+
+description: |
+  Mediatek's Keypad controller is used to interface a SoC with a matrix-type
+  keypad device. The keypad controller supports multiple row and column lines.
+  A key can be placed at each intersection of a unique row and a unique column.
+  The keypad controller can sense a key-press and key-release and report the
+  event using a interrupt to the cpu.
+
+properties:
+  compatible:
+    oneOf:
+      - const: "mediatek,mt6779-keypad"
+      - const: "mediatek,mt6873-keypad"
+
+  clock-names:
+    description: Names of the clocks listed in clocks property in the same order
+    maxItems: 1
+    items:
+    	- const: kpd
+
+  clocks:
+    description: Must contain one entry, for the module clock
+    refs: devicetree/bindings/clocks/clock-bindings.txt for details.
+
+  interrupts:
+    description: A single interrupt specifier
+    maxItems: 1
+
+  linux,keymap:
+    description: The keymap for keys as described in the binding document
+    refs: devicetree/bindings/input/matrix-keymap.txt
+    minItems: 1
+
+  reg:
+    description: The base address of the Keypad register bank
+    maxItems: 1
+
+  wakeup-source:
+    description: use any event on keypad as wakeup event
+    type: boolean
+
+  keypad,num-columns:
+    description: Number of column lines connected to the keypad controller.
+
+  keypad,num-rows:
+    description: Number of row lines connected to the keypad controller.
+
+  mediatek,debounce-us:
+    description: Debounce interval in microseconds, if not specified, the default
+    value is 16000
+    maximum: 256000
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - linux,keymap
+  - clocks
+  - clock-names
+
+examples:
+  - |
+
+  kp@10010000 {
+    compatible = "mediatek,kp";
+    reg = <0 0x10010000 0 0x1000>;
+    linux,keymap = < MATRIX_KEY(0x00, 0x00, KEY_VOLUMEDOWN) >;
+    interrupts = <GIC_SPI 75 IRQ_TYPE_EDGE_FALLING>;
+    clocks = <&clk26m>;
+    clock-names = "kpd";
+  };
-- 
2.18.0
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