[PATCH v7] Add matrix keypad driver support for Mediatek SoCs

[PATCH v7] Add matrix keypad driver support for Mediatek SoCs

[Fengping Yu]

Change since v6:
- update keypad device tree document schema

fengping.yu (3):
  dt-bindings: Add keypad devicetree documentation
  drivers: input: keyboard: Add mtk keypad driver
  configs: defconfig: Add CONFIG_KEYBOARD_MTK_KPD=y

 .../devicetree/bindings/input/mtk-kpd.yaml    | 102 ++++++++
 arch/arm64/configs/defconfig                  |   2 +
 drivers/input/keyboard/Kconfig                |   8 +
 drivers/input/keyboard/Makefile               |   1 +
 drivers/input/keyboard/mtk-kpd.c              | 223 ++++++++++++++++++
 5 files changed, 336 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/input/mtk-kpd.yaml
 create mode 100644 drivers/input/keyboard/mtk-kpd.c

--
2.18.0

Re: [PATCH v7 3/3] configs: defconfig: Add CONFIG_KEYBOARD_MTK_KPD=y

[Marco Felsch]

Hi,

On 20-05-14 14:17, Fengping Yu wrote:
> From: "fengping.yu" <fengping.yu@mediatek.com>
> 
> Add Mediatek matrix keypad support in defconfig.
> 
> Signed-off-by: fengping.yu <fengping.yu@mediatek.com>
> ---
>  arch/arm64/configs/defconfig | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/arch/arm64/configs/defconfig b/arch/arm64/configs/defconfig
> index 24e534d85045..f9f0fb489182 100644
> --- a/arch/arm64/configs/defconfig
> +++ b/arch/arm64/configs/defconfig
> @@ -349,6 +349,8 @@ CONFIG_KEYBOARD_GPIO=y
>  CONFIG_KEYBOARD_SNVS_PWRKEY=m
>  CONFIG_KEYBOARD_IMX_SC_KEY=m
>  CONFIG_KEYBOARD_CROS_EC=y
> +CONFIG_KEYBOARD_MTK_KPD=y

Why not as module?

> +# CONFIG_KEYBOARD_MTK_PMIC is not set

Also this is a unrelated add.

Regards,
  Marco

>  CONFIG_INPUT_TOUCHSCREEN=y
>  CONFIG_TOUCHSCREEN_ATMEL_MXT=m
>  CONFIG_INPUT_MISC=y
> -- 
> 2.18.0

Re: [PATCH v7 2/3] drivers: input: keyboard: Add mtk keypad driver

[Marco Felsch]

Hi,

I like the evolution of this patch =)

On 20-05-14 14:17, Fengping Yu wrote:
> From: "fengping.yu" <fengping.yu@mediatek.com>
> 
> This adds matrix keypad support for Mediatek SoCs.
> 
> Signed-off-by: fengping.yu <fengping.yu@mediatek.com>
> ---
>  drivers/input/keyboard/Kconfig   |   8 ++
>  drivers/input/keyboard/Makefile  |   1 +
>  drivers/input/keyboard/mtk-kpd.c | 223 +++++++++++++++++++++++++++++++
>  3 files changed, 232 insertions(+)
>  create mode 100644 drivers/input/keyboard/mtk-kpd.c
> 
> diff --git a/drivers/input/keyboard/Kconfig b/drivers/input/keyboard/Kconfig
> index 28de965a08d5..6bae95a5f90b 100644
> --- a/drivers/input/keyboard/Kconfig
> +++ b/drivers/input/keyboard/Kconfig
> @@ -782,6 +782,14 @@ 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 OF && HAVE_CLK
> +	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..a538f89d6696
> --- /dev/null
> +++ b/drivers/input/keyboard/mtk-kpd.c
> @@ -0,0 +1,223 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2019 MediaTek Inc.
> + * Author Terry Chang <terry.chang@mediatek.com>
> + */
> +#include <linux/clk.h>
> +#include <linux/input/matrix_keypad.h>
> +#include <linux/interrupt.h>
> +#include <linux/module.h>
> +#include <linux/property.h>
> +#include <linux/pinctrl/consumer.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +#include <linux/bitops.h>

Please sort it alphabetical.

> +#define KPD_NAME	"mtk-kpd"
> +
> +#define KP_MEM		0x0004
> +#define KP_DEBOUNCE	0x0018
> +
> +#define KPD_DEBOUNCE_MASK	GENMASK(13, 0)
> +#define KPD_DEBOUNCE_MAX_US	256000 /*256ms */
> +#define KPD_NUM_MEMS	5
> +#define KPD_NUM_BITS	136	/* 4 * 32 + 8 MEM5 only use 8 BITS */

Pls align all define values. Nit, I would also make the names a bit more
uniform e.g.
  - MTK_KPD_NAME
  - MTK_KPD_MEM
  - MTK_KPD_DEBOUNCE
  - MTK_KPD_NUM_MEMS
  ...

> +struct mtk_keypad {
> +	struct regmap *regmap;
> +	struct input_dev *input_dev;
> +	struct clk *clk;
> +	void __iomem *base;
> +	bool wakeup;
> +	u32 n_rows;
> +	u32 n_cols;
> +	DECLARE_BITMAP(keymap_state, KPD_NUM_BITS);
> +};
> +
> +static const struct regmap_config keypad_regmap_cfg = {
> +	.reg_bits = 32,
> +	.val_bits = 32,
> +	.reg_stride = sizeof(u32),
> +	.max_register = 0x0024,

IMHO we should specify max_register as decimal value.

> +};
> +
> +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, KPD_NUM_BITS);
> +	DECLARE_BITMAP(change, KPD_NUM_BITS);
> +	int bit_nr;
> +	int pressed;
> +	unsigned short code;
> +
> +	regmap_raw_read(keypad->regmap, KP_MEM, new_state, KPD_NUM_MEMS);
> +
> +	bitmap_xor(change, new_state, keypad->keymap_state, KPD_NUM_BITS);
> +
> +	for_each_set_bit(bit_nr, change, KPD_NUM_BITS) {
> +		/* 1: not pressed, 0: pressed */
> +		pressed = !test_bit(bit_nr, new_state);
> +		dev_dbg(&keypad->input_dev->dev, "%s",
> +			pressed ? "pressed" : "released");
> +
> +		/* 32bit register only use low 16bit as keypad mem register */
> +		code = keycode[bit_nr - 16 * (BITS_TO_U32(bit_nr) - 1)];
> +
> +		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, KPD_NUM_BITS);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int kpd_pdrv_probe(struct platform_device *pdev)
> +{
> +	struct mtk_keypad *keypad;
> +	struct pinctrl *keypad_pinctrl;
> +	struct pinctrl_state *kpd_default;
> +	unsigned int irqnr;
> +	u32 debounce;
> +	int ret;
> +
> +	keypad = devm_kzalloc(&pdev->dev, sizeof(*keypad), GFP_KERNEL);
> +	if (!keypad)
> +		return -ENOMEM;

Missing newline ?

> +	keypad->base = devm_platform_ioremap_resource(pdev, 0);
> +	if (IS_ERR(keypad->base))
> +		return PTR_ERR(keypad->base);
> +
> +	keypad->regmap = devm_regmap_init_mmio_clk(&pdev->dev, NULL,
> +				keypad->base, &keypad_regmap_cfg);

Pls align it and make use of devm_regmap_init_mmio().

> +	if (IS_ERR(keypad->regmap)) {
> +		dev_err(&pdev->dev,
> +			"regmap init failed:%ld\n", PTR_ERR(keypad->regmap));
> +		return PTR_ERR(keypad->regmap);
> +	}
> +
> +	bitmap_fill(keypad->keymap_state, 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 = KPD_NAME;
> +	keypad->input_dev->id.bustype = BUS_HOST;
> +
> +	ret = matrix_keypad_parse_properties(&pdev->dev, &keypad->n_rows,
> +					     &keypad->n_cols);
> +	if (ret) {
> +		dev_err(&pdev->dev, "Failed to parse keypad params\n");
> +		return ret;
> +	}
> +
> +	ret = device_property_read_u32(&pdev->dev, "mediatek,debounce-us",
> +					&debounce);
> +	if (ret) {
> +		dev_err(&pdev->dev, "Failed to read mediatek debounce time\n");
> +		return ret;
> +	}

Nit, I would make it optional and use a default if no value is
specified.

> +
> +	if (debounce > KPD_DEBOUNCE_MAX_US) {
> +		dev_err(&pdev->dev, "Debounce time exceeds the maximum allowed time 256ms\n");
> +		return -EINVAL;
> +	}
> +
> +	keypad->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);
> +
> +	ret = matrix_keypad_build_keymap(NULL, NULL,
> +					keypad->n_rows,
> +					keypad->n_cols,
> +					NULL,
> +					keypad->input_dev);

Pls align it correctly.

> +	if (ret) {
> +		dev_err(&pdev->dev, "Failed to build keymap\n");
> +		return ret;
> +	}
> +
> +	input_set_drvdata(keypad->input_dev, keypad);
> +
> +	regmap_write(keypad->regmap, KP_DEBOUNCE,
> +			debounce * 32 / 1000 & KPD_DEBOUNCE_MASK);

Pls align this also.

> +
> +	keypad->clk = devm_clk_get(&pdev->dev, "kpd");
> +	if (IS_ERR(keypad->clk)) {
> +		return PTR_ERR(keypad->clk);
> +	}

Not needed braces.

> +
> +	ret = clk_prepare_enable(keypad->clk);
> +	if (ret) {
> +		dev_err(&pdev->dev, "cannot prepare/enable keypad clock\n");
> +		return ret;
> +	}
> +
> +	devm_add_action_or_reset(&pdev->dev,
> +				(void (*)(void *))clk_disable_unprepare,
> +				keypad->clk);

Pls don't do that and instead add a internal driver function.

> +
> +	keypad_pinctrl = devm_pinctrl_get(&pdev->dev);
> +	if (IS_ERR(keypad_pinctrl)) {
> +		return PTR_ERR(keypad_pinctrl);
> +	}

Not needed braces.

> +
> +	kpd_default = pinctrl_lookup_state(keypad_pinctrl, "default");
> +	if (IS_ERR(kpd_default)) {
> +		dev_err(&pdev->dev, "No default pinctrl state\n");
> +		return PTR_ERR(kpd_default);
> +	}
> +
> +	pinctrl_select_state(keypad_pinctrl, kpd_default);
> +
> +	irqnr = platform_get_irq(pdev, 0);
> +	if (irqnr < 0) {
> +		dev_err(&pdev->dev, "Failed to get irq\n");
> +		return -irqnr;
> +	}
> +
> +	ret = devm_request_threaded_irq(&pdev->dev, irqnr,
> +				NULL, kpd_irq_handler, 0,
> +				KPD_NAME, keypad);
> +	if (ret) {
> +		dev_err(&pdev->dev, "Failed to request IRQ#%d:%d\n",
> +						irqnr, ret);
> +		return ret;
> +	}
> +
> +	ret = input_register_device(keypad->input_dev);
> +	if (ret) {
> +		dev_err(&pdev->dev, "Failed to register device\n");
> +		return ret;
> +	}
> +
> +	device_init_wakeup(&pdev->dev, keypad->wakeup);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id kpd_of_match[] = {
> +	{.compatible = "mediatek,kp"},

I would also add the specific compatible which you list in the
dt-bindings patch.

> +	{/*sentinel*/}
> +};
> +
> +static struct platform_driver kpd_pdrv = {
> +	.probe = kpd_pdrv_probe,
> +	.driver = {
> +		   .name = 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

Pls use checkpatch the next time, there are several style issues. Also
it is quite common to use a vendor prefix for funtions e.g.
mtk_kpd_probe() and mtk_kpd_irq_handler() but this is up to you.

Regards,
  Marco

Re: [PATCH v7 2/3] drivers: input: keyboard: Add mtk keypad driver

[Andy Shevchenko]

On Thu, May 14, 2020 at 02:17:48PM +0800, Fengping Yu wrote:
> From: "fengping.yu" <fengping.yu@mediatek.com>
> 
> This adds matrix keypad support for Mediatek SoCs.

...

> +config KEYBOARD_MTK_KPD
> +	tristate "MediaTek Keypad Support"

> +	depends on OF && HAVE_CLK

What makes it OF dependent?

> +	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.

...

> +#define KPD_DEBOUNCE_MAX_US	256000 /*256ms */

Comment, besides missed space, is redundant. That's how we use unit suffixes in
the definitions.

...

> +static const struct regmap_config keypad_regmap_cfg = {
> +	.reg_bits = 32,
> +	.val_bits = 32,
> +	.reg_stride = sizeof(u32),

> +	.max_register = 0x0024,

Can it be definition?

> +};

...

> +	keypad = devm_kzalloc(&pdev->dev, sizeof(*keypad), GFP_KERNEL);
> +	if (!keypad)
> +		return -ENOMEM;

+ blank line here.

> +	keypad->base = devm_platform_ioremap_resource(pdev, 0);
> +	if (IS_ERR(keypad->base))
> +		return PTR_ERR(keypad->base);

...

> +	if (debounce > KPD_DEBOUNCE_MAX_US) {
> +		dev_err(&pdev->dev, "Debounce time exceeds the maximum allowed time 256ms\n");

	...%dus\n", KPD_DEBOUNCE_MAX_US);
or
	...%dms\n", KPD_DEBOUNCE_MAX_US / USEC_PER_MSEC);

> +		return -EINVAL;
> +	}

...

> +	keypad_pinctrl = devm_pinctrl_get(&pdev->dev);

> +	if (IS_ERR(keypad_pinctrl)) {
> +		return PTR_ERR(keypad_pinctrl);
> +	}

Extra {}.

...

> +	kpd_default = pinctrl_lookup_state(keypad_pinctrl, "default");
> +	if (IS_ERR(kpd_default)) {

> +		dev_err(&pdev->dev, "No default pinctrl state\n");

Isn't it done by pin control core?

> +		return PTR_ERR(kpd_default);
> +	}
> +
> +	pinctrl_select_state(keypad_pinctrl, kpd_default);

And basically entire part is duplicating device core part? (Look at dd.c)

...

> +	irqnr = platform_get_irq(pdev, 0);
> +	if (irqnr < 0) {

> +		dev_err(&pdev->dev, "Failed to get irq\n");

This duplicates what platform core does.

> +		return -irqnr;

- ?!

> +	}

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v7 2/3] drivers: input: keyboard: Add mtk keypad driver

[Andy Shevchenko]

On Thu, May 14, 2020 at 01:27:01PM +0300, Andy Shevchenko wrote:
> On Thu, May 14, 2020 at 02:17:48PM +0800, Fengping Yu wrote:
> > From: "fengping.yu" <fengping.yu@mediatek.com>
> > 
> > This adds matrix keypad support for Mediatek SoCs.
> 
> ...
> 
> > +config KEYBOARD_MTK_KPD
> > +	tristate "MediaTek Keypad Support"
> 
> > +	depends on OF && HAVE_CLK
> 
> What makes it OF dependent?

Actually you missed regmap dependencies or selection. I dunno which one should
be used (IIRC selection).

> > +	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.


-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v7 1/3] dt-bindings: Add keypad devicetree documentation

[Marco Felsch]

Hi,

On 20-05-14 14:17, Fengping Yu wrote:
> From: "fengping.yu" <fengping.yu@mediatek.com>
> 
> Add Mediatek matrix keypad dt-binding doc as yaml schema.
> 
> Signed-off-by: fengping.yu <fengping.yu@mediatek.com>
> ---
>  .../devicetree/bindings/input/mtk-kpd.yaml    | 102 ++++++++++++++++++
>  1 file changed, 102 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..8f594fe0bfc2
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/input/mtk-kpd.yaml
> @@ -0,0 +1,102 @@
> +%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:
> +      constraint: |

enum or const ?

> +        "mediatek,mt6779-keypad"
> +        "mediatek, kp"
> +
> +    clock-names:
> +	description: Names of the clocks listed in clocks property in the same order
> +
> +    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
> +
> +    linux,keymap:
> +	description: The keymap for keys as described in the binding document
> +	refs: devicetree/bindings/input/matrix-keymap.txt
> +
> +    pinctrl-0:
> +	description: Specify pin control groups used for this controller
> +	refs: devicetree/bindings/pinctrl/pinctrl-bindings.txt
> +
> +    pinctrl-names:
> +	description: Names for optional pin modes
> +
> +    reg:
> +	description: The base address of the Keypad register bank
> +
> +    wakeup-source:
> +	description: use any event on keypad as wakeup event
> +
> +    keypad,num-columns:
> +	description: Number of column lines connected to the keypad controller,
> + 	it is not equal to PCB columns number, instead you should add required value
> + 	for each IC
> +
> +    keypad,num-rows:
> +	description: Number of row lines connected to the keypad controller, it is
> + 	not equal to PCB rows number, instead you should add required value for each IC
> +
> +    mediatek,debounce-us:
> +	description: Debounce interval in microseconds
> +	maximum: 256000

I think that you are missing the maxItems on all your properties so we
can't make any validation. Also the indent looks wrong.

> +
> +
> +required:
> +  - compatible
> +  - reg
> +  - interrupts
> +  - mediatek,debounce-us
> +  - keypad,num-rows
> +  - keypad,num-columns
> +  - linux,keymap
> +  - pinctrl
> +  - clocks
> +  - clock-names
> +
> +optional:
> +  - wakeup-source:

I think the optional can be dropped.

> +examples:
> +  - |
> +
> +    keypad: kp@10010000 {
> +	compatible = "mediatek,kp";
> +	reg = <0 0x10010000 0 0x1000>;
> +	wakeup-source;
> +	interrupts = <GIC_SPI 75 IRQ_TYPE_EDGE_FALLING>;
> +	clocks = <&clk26m>;
> +	clock-names = "kpd";
> +    };
> +
> +    &keypad {
> +	mediatek,debounce-us = <32000>;
> +	keypad,num-rows = <8>;
> +	keypad,num-columns = <9>;
> +	linux,keymap = < MATRIX_KEY(0x00, 0x00, KEY_VOLUMEDOWN) >;
> +	status = "okay";
> +	pinctrl-names = "default";
> +	pinctrl-0 = <&kpd_gpios_def_cfg>;
> +    };

Pls squash those nodes.

Regards,
  Marco

> -- 
> 2.18.0

Re: [PATCH v7 1/3] dt-bindings: Add keypad devicetree documentation

[Matthias Brugger]

On 14/05/2020 08:17, Fengping Yu wrote:
> From: "fengping.yu" <fengping.yu@mediatek.com>
> 
> Add Mediatek matrix keypad dt-binding doc as yaml schema.
> 
> Signed-off-by: fengping.yu <fengping.yu@mediatek.com>
> ---
>  .../devicetree/bindings/input/mtk-kpd.yaml    | 102 ++++++++++++++++++
>  1 file changed, 102 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..8f594fe0bfc2
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/input/mtk-kpd.yaml
> @@ -0,0 +1,102 @@
> +%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:
> +      constraint: |
> +        "mediatek,mt6779-keypad"
> +        "mediatek, kp"

"mediatek, kp" is too generic. Are you aware that the keypad can be used by
other SoCs. Then we should add them later with a fallback to mt6779-keypad.

Regards,
Matthias

> +
> +    clock-names:
> +	description: Names of the clocks listed in clocks property in the same order
> +
> +    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
> +
> +    linux,keymap:
> +	description: The keymap for keys as described in the binding document
> +	refs: devicetree/bindings/input/matrix-keymap.txt
> +
> +    pinctrl-0:
> +	description: Specify pin control groups used for this controller
> +	refs: devicetree/bindings/pinctrl/pinctrl-bindings.txt
> +
> +    pinctrl-names:
> +	description: Names for optional pin modes
> +
> +    reg:
> +	description: The base address of the Keypad register bank
> +
> +    wakeup-source:
> +	description: use any event on keypad as wakeup event
> +
> +    keypad,num-columns:
> +	description: Number of column lines connected to the keypad controller,
> + 	it is not equal to PCB columns number, instead you should add required value
> + 	for each IC
> +
> +    keypad,num-rows:
> +	description: Number of row lines connected to the keypad controller, it is
> + 	not equal to PCB rows number, instead you should add required value for each IC
> +
> +    mediatek,debounce-us:
> +	description: Debounce interval in microseconds
> +	maximum: 256000
> +
> +
> +required:
> +  - compatible
> +  - reg
> +  - interrupts
> +  - mediatek,debounce-us
> +  - keypad,num-rows
> +  - keypad,num-columns
> +  - linux,keymap
> +  - pinctrl
> +  - clocks
> +  - clock-names
> +
> +optional:
> +  - wakeup-source:
> +
> +examples:
> +  - |
> +
> +    keypad: kp@10010000 {
> +	compatible = "mediatek,kp";
> +	reg = <0 0x10010000 0 0x1000>;
> +	wakeup-source;
> +	interrupts = <GIC_SPI 75 IRQ_TYPE_EDGE_FALLING>;
> +	clocks = <&clk26m>;
> +	clock-names = "kpd";
> +    };
> +
> +    &keypad {
> +	mediatek,debounce-us = <32000>;
> +	keypad,num-rows = <8>;
> +	keypad,num-columns = <9>;
> +	linux,keymap = < MATRIX_KEY(0x00, 0x00, KEY_VOLUMEDOWN) >;
> +	status = "okay";
> +	pinctrl-names = "default";
> +	pinctrl-0 = <&kpd_gpios_def_cfg>;
> +    };
>