Add driver for Maxim Integrated MAX7360 keypad controller, providing
support for up to 64 keys, with a matrix of 8 columns and 8 rows.

Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
---
 drivers/input/keyboard/Kconfig          |  12 ++
 drivers/input/keyboard/Makefile         |   1 +
 drivers/input/keyboard/max7360-keypad.c | 299 ++++++++++++++++++++++++++++++++
 3 files changed, 312 insertions(+)

diff --git a/drivers/input/keyboard/Kconfig b/drivers/input/keyboard/Kconfig
index 721ab69e84ac..93b5cccf6892 100644
--- a/drivers/input/keyboard/Kconfig
+++ b/drivers/input/keyboard/Kconfig
@@ -421,6 +421,18 @@ config KEYBOARD_MAX7359
 	  To compile this driver as a module, choose M here: the
 	  module will be called max7359_keypad.
 
+config KEYBOARD_MAX7360
+	tristate "Maxim MAX7360 Key Switch Controller"
+	select INPUT_MATRIXKMAP
+	depends on I2C
+	depends on MFD_MAX7360
+	help
+	  If you say yes here you get support for the keypad controller on the
+	  Maxim MAX7360 I/O Expander.
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called max7360_keypad.
+
 config KEYBOARD_MPR121
 	tristate "Freescale MPR121 Touchkey"
 	depends on I2C
diff --git a/drivers/input/keyboard/Makefile b/drivers/input/keyboard/Makefile
index 1e0721c30709..b49d32d4003d 100644
--- a/drivers/input/keyboard/Makefile
+++ b/drivers/input/keyboard/Makefile
@@ -42,6 +42,7 @@ obj-$(CONFIG_KEYBOARD_LPC32XX)		+= lpc32xx-keys.o
 obj-$(CONFIG_KEYBOARD_MAPLE)		+= maple_keyb.o
 obj-$(CONFIG_KEYBOARD_MATRIX)		+= matrix_keypad.o
 obj-$(CONFIG_KEYBOARD_MAX7359)		+= max7359_keypad.o
+obj-$(CONFIG_KEYBOARD_MAX7360)		+= max7360-keypad.o
 obj-$(CONFIG_KEYBOARD_MPR121)		+= mpr121_touchkey.o
 obj-$(CONFIG_KEYBOARD_MT6779)		+= mt6779-keypad.o
 obj-$(CONFIG_KEYBOARD_MTK_PMIC) 	+= mtk-pmic-keys.o
diff --git a/drivers/input/keyboard/max7360-keypad.c b/drivers/input/keyboard/max7360-keypad.c
new file mode 100644
index 000000000000..d0066636e5c2
--- /dev/null
+++ b/drivers/input/keyboard/max7360-keypad.c
@@ -0,0 +1,299 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2025 Bootlin
+ *
+ * Author: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
+ */
+
+#include <linux/bitfield.h>
+#include <linux/bitops.h>
+#include <linux/dev_printk.h>
+#include <linux/device/devres.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/input.h>
+#include <linux/input/matrix_keypad.h>
+#include <linux/interrupt.h>
+#include <linux/mfd/max7360.h>
+#include <linux/mod_devicetable.h>
+#include <linux/minmax.h>
+#include <linux/module.h>
+#include <linux/property.h>
+#include <linux/platform_device.h>
+#include <linux/pm_wakeirq.h>
+#include <linux/regmap.h>
+
+struct max7360_keypad {
+	struct input_dev *input;
+	unsigned int rows;
+	unsigned int cols;
+	unsigned int debounce_ms;
+	int irq;
+	struct regmap *regmap;
+	unsigned short keycodes[MAX7360_MAX_KEY_ROWS * MAX7360_MAX_KEY_COLS];
+};
+
+static irqreturn_t max7360_keypad_irq(int irq, void *data)
+{
+	struct max7360_keypad *max7360_keypad = data;
+	unsigned int val;
+	unsigned int row, col;
+	unsigned int release;
+	unsigned int code;
+	int ret;
+
+	do {
+		ret = regmap_read(max7360_keypad->regmap, MAX7360_REG_KEYFIFO, &val);
+		if (ret) {
+			dev_err(&max7360_keypad->input->dev, "Failed to read max7360 FIFO");
+			return IRQ_NONE;
+		}
+
+		/* FIFO overflow: ignore it and get next event. */
+		if (val == MAX7360_FIFO_OVERFLOW)
+			dev_warn(&max7360_keypad->input->dev, "max7360 FIFO overflow");
+	} while (val == MAX7360_FIFO_OVERFLOW);
+
+	if (val == MAX7360_FIFO_EMPTY) {
+		dev_dbg(&max7360_keypad->input->dev, "Got a spurious interrupt");
+
+		return IRQ_NONE;
+	}
+
+	row = FIELD_GET(MAX7360_FIFO_ROW, val);
+	col = FIELD_GET(MAX7360_FIFO_COL, val);
+	release = val & MAX7360_FIFO_RELEASE;
+
+	code = MATRIX_SCAN_CODE(row, col, MAX7360_ROW_SHIFT);
+
+	dev_dbg(&max7360_keypad->input->dev, "key[%d:%d] %s\n", row, col,
+		release ? "release" : "press");
+
+	input_event(max7360_keypad->input, EV_MSC, MSC_SCAN, code);
+	input_report_key(max7360_keypad->input, max7360_keypad->keycodes[code], !release);
+	input_sync(max7360_keypad->input);
+
+	return IRQ_HANDLED;
+}
+
+static int max7360_keypad_open(struct input_dev *pdev)
+{
+	struct max7360_keypad *max7360_keypad = input_get_drvdata(pdev);
+	int ret;
+
+	/* Somebody is using the device: get out of sleep. */
+	ret = regmap_write_bits(max7360_keypad->regmap, MAX7360_REG_CONFIG,
+				MAX7360_CFG_SLEEP, MAX7360_CFG_SLEEP);
+	if (ret)
+		dev_err(&max7360_keypad->input->dev, "Failed to write max7360 configuration\n");
+
+	return ret;
+}
+
+static void max7360_keypad_close(struct input_dev *pdev)
+{
+	struct max7360_keypad *max7360_keypad = input_get_drvdata(pdev);
+	int ret;
+
+	/* Nobody is using the device anymore: go to sleep. */
+	ret = regmap_write_bits(max7360_keypad->regmap, MAX7360_REG_CONFIG, MAX7360_CFG_SLEEP, 0);
+	if (ret)
+		dev_err(&max7360_keypad->input->dev,
+			"Failed to write max7360 configuration\n");
+}
+
+static int max7360_keypad_hw_init(struct max7360_keypad *max7360_keypad)
+{
+	unsigned int val;
+	int ret;
+
+	val = max7360_keypad->debounce_ms - MAX7360_DEBOUNCE_MIN;
+	ret = regmap_write_bits(max7360_keypad->regmap, MAX7360_REG_DEBOUNCE,
+				MAX7360_DEBOUNCE,
+				FIELD_PREP(MAX7360_DEBOUNCE, val));
+	if (ret) {
+		return dev_err_probe(&max7360_keypad->input->dev, ret,
+			"Failed to write max7360 debounce configuration\n");
+	}
+
+	ret = regmap_write_bits(max7360_keypad->regmap, MAX7360_REG_INTERRUPT,
+				MAX7360_INTERRUPT_TIME_MASK,
+				FIELD_PREP(MAX7360_INTERRUPT_TIME_MASK, 1));
+	if (ret) {
+		return dev_err_probe(&max7360_keypad->input->dev, ret,
+			"Failed to write max7360 keypad interrupt configuration\n");
+	}
+
+	return 0;
+}
+
+static int max7360_keypad_build_keymap(struct max7360_keypad *max7360_keypad)
+{
+	struct input_dev *input_dev = max7360_keypad->input;
+	struct device *dev = input_dev->dev.parent->parent;
+	struct matrix_keymap_data keymap_data;
+	const char *propname = "linux,keymap";
+	unsigned int max_keys;
+	int size;
+	int ret;
+
+	size = device_property_count_u32(dev, propname);
+	if (size <= 0) {
+		dev_err(dev, "missing or malformed property %s: %d\n", propname, size);
+		return size < 0 ? size : -EINVAL;
+	}
+
+	max_keys = max7360_keypad->cols * max7360_keypad->rows;
+	if (size > max_keys) {
+		dev_err(dev, "%s size overflow (%d vs max %u)\n", propname, size, max_keys);
+		return -EINVAL;
+	}
+
+	u32 *keys __free(kfree) = kmalloc_array(size, sizeof(*keys), GFP_KERNEL);
+	if (!keys)
+		return -ENOMEM;
+
+	ret = device_property_read_u32_array(dev, propname, keys, size);
+	if (ret) {
+		dev_err(dev, "failed to read %s property: %d\n", propname, ret);
+		return ret;
+	}
+
+	keymap_data.keymap = keys;
+	keymap_data.keymap_size = size;
+	ret = matrix_keypad_build_keymap(&keymap_data, NULL, max7360_keypad->rows, max7360_keypad->cols,
+					 max7360_keypad->keycodes, max7360_keypad->input);
+
+	return 0;
+}
+
+static int max7360_keypad_parse_fw(struct device *dev,
+				   struct max7360_keypad *max7360_keypad,
+				   bool *autorepeat)
+{
+	int ret;
+
+	ret = matrix_keypad_parse_properties(dev->parent, &max7360_keypad->rows,
+					     &max7360_keypad->cols);
+	if (ret)
+		return ret;
+
+	if (!max7360_keypad->rows || !max7360_keypad->cols ||
+	    max7360_keypad->rows > MAX7360_MAX_KEY_ROWS ||
+	    max7360_keypad->cols > MAX7360_MAX_KEY_COLS) {
+		dev_err(dev, "Invalid number of columns or rows (%ux%u)\n",
+			max7360_keypad->cols, max7360_keypad->rows);
+		return -EINVAL;
+	}
+
+	*autorepeat = device_property_read_bool(dev->parent, "autorepeat");
+
+	max7360_keypad->debounce_ms = MAX7360_DEBOUNCE_MIN;
+	ret = device_property_read_u32(dev->parent, "keypad-debounce-delay-ms",
+				       &max7360_keypad->debounce_ms);
+	if (ret == -EINVAL) {
+		dev_info(dev, "Using default keypad-debounce-delay-ms: %u\n",
+			 max7360_keypad->debounce_ms);
+	} else if (ret < 0) {
+		dev_err(dev, "Failed to read keypad-debounce-delay-ms property\n");
+		return ret;
+	}
+
+	if (!in_range(max7360_keypad->debounce_ms, MAX7360_DEBOUNCE_MIN,
+		      MAX7360_DEBOUNCE_MAX - MAX7360_DEBOUNCE_MIN)) {
+		dev_err(dev, "Invalid keypad-debounce-delay-ms: %u, should be between %u and %u.\n",
+			max7360_keypad->debounce_ms, MAX7360_DEBOUNCE_MIN, MAX7360_DEBOUNCE_MAX);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int max7360_keypad_probe(struct platform_device *pdev)
+{
+	struct max7360_keypad *max7360_keypad;
+	struct device *dev = &pdev->dev;
+	struct input_dev *input;
+	struct regmap *regmap;
+	bool autorepeat;
+	int ret;
+	int irq;
+
+	regmap = dev_get_regmap(dev->parent, NULL);
+	if (!regmap)
+		dev_err_probe(dev, -ENODEV, "Could not get parent regmap\n");
+
+	irq = fwnode_irq_get_byname(dev_fwnode(dev->parent), "intk");
+	if (irq < 0)
+		return dev_err_probe(dev, irq, "Failed to get IRQ\n");
+
+	max7360_keypad = devm_kzalloc(dev, sizeof(*max7360_keypad), GFP_KERNEL);
+	if (!max7360_keypad)
+		return -ENOMEM;
+
+	max7360_keypad->regmap = regmap;
+
+	ret = max7360_keypad_parse_fw(dev, max7360_keypad, &autorepeat);
+	if (ret)
+		return ret;
+
+	input = devm_input_allocate_device(dev);
+	if (!input)
+		return -ENOMEM;
+
+	max7360_keypad->input = input;
+
+	input->id.bustype = BUS_I2C;
+	input->name = pdev->name;
+	input->open = max7360_keypad_open;
+	input->close = max7360_keypad_close;
+
+	ret = max7360_keypad_build_keymap(max7360_keypad);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to build keymap\n");
+
+	input_set_capability(input, EV_MSC, MSC_SCAN);
+	if (autorepeat)
+		__set_bit(EV_REP, input->evbit);
+
+	input_set_drvdata(input, max7360_keypad);
+
+	ret = devm_request_threaded_irq(dev, irq, NULL, max7360_keypad_irq,
+					IRQF_ONESHOT,
+					"max7360-keypad", max7360_keypad);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to register interrupt\n");
+
+	ret = input_register_device(input);
+	if (ret)
+		return dev_err_probe(dev, ret, "Could not register input device\n");
+
+	ret = max7360_keypad_hw_init(max7360_keypad);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to initialize max7360 keypad\n");
+
+	device_init_wakeup(dev, true);
+	ret = dev_pm_set_wake_irq(dev, irq);
+	if (ret)
+		dev_warn(dev, "Failed to set up wakeup irq: %d\n", ret);
+
+	return 0;
+}
+
+static void max7360_keypad_remove(struct platform_device *pdev)
+{
+	dev_pm_clear_wake_irq(&pdev->dev);
+}
+
+static struct platform_driver max7360_keypad_driver = {
+	.driver = {
+		.name	= "max7360-keypad",
+	},
+	.probe		= max7360_keypad_probe,
+	.remove		= max7360_keypad_remove,
+};
+module_platform_driver(max7360_keypad_driver);
+
+MODULE_DESCRIPTION("MAX7360 Keypad driver");
+MODULE_AUTHOR("Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>");
+MODULE_LICENSE("GPL");

-- 
2.39.5

Hi Mathieu,

On Wed, Apr 09, 2025 at 04:55:57PM +0200, Mathieu Dubois-Briand wrote:
> +struct max7360_keypad {
> +	struct input_dev *input;
> +	unsigned int rows;
> +	unsigned int cols;
> +	unsigned int debounce_ms;
> +	int irq;
> +	struct regmap *regmap;
> +	unsigned short keycodes[MAX7360_MAX_KEY_ROWS * MAX7360_MAX_KEY_COLS];
> +};
> +
> +static irqreturn_t max7360_keypad_irq(int irq, void *data)
> +{
> +	struct max7360_keypad *max7360_keypad = data;
> +	unsigned int val;
> +	unsigned int row, col;
> +	unsigned int release;
> +	unsigned int code;
> +	int ret;

int error;

> +
> +	do {
> +		ret = regmap_read(max7360_keypad->regmap, MAX7360_REG_KEYFIFO, &val);
> +		if (ret) {
> +			dev_err(&max7360_keypad->input->dev, "Failed to read max7360 FIFO");

This will return name pf the input device, whereas logging name of the
platform device (representing the hardware device) would be much more
interesting. You can either use max7360_keypad->input->dev.parent, or,
better yet, add *dev pointer to struct max7360_keypad.

> +			return IRQ_NONE;
> +		}
> +
> +		/* FIFO overflow: ignore it and get next event. */
> +		if (val == MAX7360_FIFO_OVERFLOW)
> +			dev_warn(&max7360_keypad->input->dev, "max7360 FIFO overflow");
> +	} while (val == MAX7360_FIFO_OVERFLOW);
> +
> +	if (val == MAX7360_FIFO_EMPTY) {
> +		dev_dbg(&max7360_keypad->input->dev, "Got a spurious interrupt");
> +
> +		return IRQ_NONE;
> +	}
> +
> +	row = FIELD_GET(MAX7360_FIFO_ROW, val);
> +	col = FIELD_GET(MAX7360_FIFO_COL, val);
> +	release = val & MAX7360_FIFO_RELEASE;
> +
> +	code = MATRIX_SCAN_CODE(row, col, MAX7360_ROW_SHIFT);
> +
> +	dev_dbg(&max7360_keypad->input->dev, "key[%d:%d] %s\n", row, col,
> +		release ? "release" : "press");
> +
> +	input_event(max7360_keypad->input, EV_MSC, MSC_SCAN, code);
> +	input_report_key(max7360_keypad->input, max7360_keypad->keycodes[code], !release);
> +	input_sync(max7360_keypad->input);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int max7360_keypad_open(struct input_dev *pdev)
> +{
> +	struct max7360_keypad *max7360_keypad = input_get_drvdata(pdev);
> +	int ret;

"int error" for variables holding error codes or 0. Also elsewhere in
the driver.

> +
> +	/* Somebody is using the device: get out of sleep. */
> +	ret = regmap_write_bits(max7360_keypad->regmap, MAX7360_REG_CONFIG,
> +				MAX7360_CFG_SLEEP, MAX7360_CFG_SLEEP);
> +	if (ret)
> +		dev_err(&max7360_keypad->input->dev, "Failed to write max7360 configuration\n");

Log error code?

Explicit error return please.
		retrun error;
	}
> +
> +	return ret;

	return 0;

> +}
> +
> +static void max7360_keypad_close(struct input_dev *pdev)
> +{
> +	struct max7360_keypad *max7360_keypad = input_get_drvdata(pdev);
> +	int ret;
> +
> +	/* Nobody is using the device anymore: go to sleep. */
> +	ret = regmap_write_bits(max7360_keypad->regmap, MAX7360_REG_CONFIG, MAX7360_CFG_SLEEP, 0);
> +	if (ret)
> +		dev_err(&max7360_keypad->input->dev,
> +			"Failed to write max7360 configuration\n");

Log error code?

> +}
> +
> +static int max7360_keypad_hw_init(struct max7360_keypad *max7360_keypad)
> +{
> +	unsigned int val;
> +	int ret;
> +
> +	val = max7360_keypad->debounce_ms - MAX7360_DEBOUNCE_MIN;
> +	ret = regmap_write_bits(max7360_keypad->regmap, MAX7360_REG_DEBOUNCE,
> +				MAX7360_DEBOUNCE,
> +				FIELD_PREP(MAX7360_DEBOUNCE, val));
> +	if (ret) {
> +		return dev_err_probe(&max7360_keypad->input->dev, ret,
> +			"Failed to write max7360 debounce configuration\n");
> +	}

No need for braces with single line statements.

> +
> +	ret = regmap_write_bits(max7360_keypad->regmap, MAX7360_REG_INTERRUPT,
> +				MAX7360_INTERRUPT_TIME_MASK,
> +				FIELD_PREP(MAX7360_INTERRUPT_TIME_MASK, 1));
> +	if (ret) {
> +		return dev_err_probe(&max7360_keypad->input->dev, ret,
> +			"Failed to write max7360 keypad interrupt configuration\n");
> +	}
> +
> +	return 0;
> +}
> +
> +static int max7360_keypad_build_keymap(struct max7360_keypad *max7360_keypad)
> +{
> +	struct input_dev *input_dev = max7360_keypad->input;
> +	struct device *dev = input_dev->dev.parent->parent;
> +	struct matrix_keymap_data keymap_data;
> +	const char *propname = "linux,keymap";
> +	unsigned int max_keys;
> +	int size;
> +	int ret;
> +
> +	size = device_property_count_u32(dev, propname);
> +	if (size <= 0) {
> +		dev_err(dev, "missing or malformed property %s: %d\n", propname, size);
> +		return size < 0 ? size : -EINVAL;
> +	}
> +
> +	max_keys = max7360_keypad->cols * max7360_keypad->rows;
> +	if (size > max_keys) {
> +		dev_err(dev, "%s size overflow (%d vs max %u)\n", propname, size, max_keys);
> +		return -EINVAL;
> +	}
> +
> +	u32 *keys __free(kfree) = kmalloc_array(size, sizeof(*keys), GFP_KERNEL);
> +	if (!keys)
> +		return -ENOMEM;
> +
> +	ret = device_property_read_u32_array(dev, propname, keys, size);
> +	if (ret) {
> +		dev_err(dev, "failed to read %s property: %d\n", propname, ret);
> +		return ret;
> +	}
> +
> +	keymap_data.keymap = keys;
> +	keymap_data.keymap_size = size;
> +	ret = matrix_keypad_build_keymap(&keymap_data, NULL, max7360_keypad->rows, max7360_keypad->cols,
> +					 max7360_keypad->keycodes, max7360_keypad->input);

What if it fails? Error handling please.

Also, it looks like you are repeating what matrix_keypad_build_keymap()
is already doing. If you pass NULL as keymap data, won't it do the right
thing?

> +
> +	return 0;
> +}
> +
> +static int max7360_keypad_parse_fw(struct device *dev,
> +				   struct max7360_keypad *max7360_keypad,
> +				   bool *autorepeat)
> +{
> +	int ret;
> +
> +	ret = matrix_keypad_parse_properties(dev->parent, &max7360_keypad->rows,
> +					     &max7360_keypad->cols);
> +	if (ret)
> +		return ret;
> +
> +	if (!max7360_keypad->rows || !max7360_keypad->cols ||
> +	    max7360_keypad->rows > MAX7360_MAX_KEY_ROWS ||
> +	    max7360_keypad->cols > MAX7360_MAX_KEY_COLS) {
> +		dev_err(dev, "Invalid number of columns or rows (%ux%u)\n",
> +			max7360_keypad->cols, max7360_keypad->rows);
> +		return -EINVAL;
> +	}
> +
> +	*autorepeat = device_property_read_bool(dev->parent, "autorepeat");
> +
> +	max7360_keypad->debounce_ms = MAX7360_DEBOUNCE_MIN;
> +	ret = device_property_read_u32(dev->parent, "keypad-debounce-delay-ms",
> +				       &max7360_keypad->debounce_ms);
> +	if (ret == -EINVAL) {
> +		dev_info(dev, "Using default keypad-debounce-delay-ms: %u\n",
> +			 max7360_keypad->debounce_ms);
> +	} else if (ret < 0) {
> +		dev_err(dev, "Failed to read keypad-debounce-delay-ms property\n");
> +		return ret;
> +	}
> +
> +	if (!in_range(max7360_keypad->debounce_ms, MAX7360_DEBOUNCE_MIN,
> +		      MAX7360_DEBOUNCE_MAX - MAX7360_DEBOUNCE_MIN)) {
> +		dev_err(dev, "Invalid keypad-debounce-delay-ms: %u, should be between %u and %u.\n",
> +			max7360_keypad->debounce_ms, MAX7360_DEBOUNCE_MIN, MAX7360_DEBOUNCE_MAX);
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
> +static int max7360_keypad_probe(struct platform_device *pdev)
> +{
> +	struct max7360_keypad *max7360_keypad;
> +	struct device *dev = &pdev->dev;
> +	struct input_dev *input;
> +	struct regmap *regmap;
> +	bool autorepeat;
> +	int ret;
> +	int irq;
> +
> +	regmap = dev_get_regmap(dev->parent, NULL);
> +	if (!regmap)
> +		dev_err_probe(dev, -ENODEV, "Could not get parent regmap\n");

		return dev_err_probe(...) ?

Thanks.

-- 
Dmitry

On Wed Apr 9, 2025 at 8:40 PM CEST, Dmitry Torokhov wrote:
> Hi Mathieu,
>
> On Wed, Apr 09, 2025 at 04:55:57PM +0200, Mathieu Dubois-Briand wrote:
> ...
>> +static irqreturn_t max7360_keypad_irq(int irq, void *data)
>> +{
>> +	struct max7360_keypad *max7360_keypad = data;
>> +	unsigned int val;
>> +	unsigned int row, col;
>> +	unsigned int release;
>> +	unsigned int code;
>> +	int ret;
>
> int error;
>

Ok using error on all similar cases.

>> +
>> +	do {
>> +		ret = regmap_read(max7360_keypad->regmap, MAX7360_REG_KEYFIFO, &val);
>> +		if (ret) {
>> +			dev_err(&max7360_keypad->input->dev, "Failed to read max7360 FIFO");
>
> This will return name pf the input device, whereas logging name of the
> platform device (representing the hardware device) would be much more
> interesting. You can either use max7360_keypad->input->dev.parent, or,
> better yet, add *dev pointer to struct max7360_keypad.
>

Makes sense, thanks.

> ...
>
>> +static int max7360_keypad_build_keymap(struct max7360_keypad *max7360_keypad)
>> +{
>> +	struct input_dev *input_dev = max7360_keypad->input;
>> +	struct device *dev = input_dev->dev.parent->parent;
>> +	struct matrix_keymap_data keymap_data;
>> +	const char *propname = "linux,keymap";
>> +	unsigned int max_keys;
>> +	int size;
>> +	int ret;
>> +
>> +	size = device_property_count_u32(dev, propname);
>> +	if (size <= 0) {
>> +		dev_err(dev, "missing or malformed property %s: %d\n", propname, size);
>> +		return size < 0 ? size : -EINVAL;
>> +	}
>> +
>> +	max_keys = max7360_keypad->cols * max7360_keypad->rows;
>> +	if (size > max_keys) {
>> +		dev_err(dev, "%s size overflow (%d vs max %u)\n", propname, size, max_keys);
>> +		return -EINVAL;
>> +	}
>> +
>> +	u32 *keys __free(kfree) = kmalloc_array(size, sizeof(*keys), GFP_KERNEL);
>> +	if (!keys)
>> +		return -ENOMEM;
>> +
>> +	ret = device_property_read_u32_array(dev, propname, keys, size);
>> +	if (ret) {
>> +		dev_err(dev, "failed to read %s property: %d\n", propname, ret);
>> +		return ret;
>> +	}
>> +
>> +	keymap_data.keymap = keys;
>> +	keymap_data.keymap_size = size;
>> +	ret = matrix_keypad_build_keymap(&keymap_data, NULL, max7360_keypad->rows, max7360_keypad->cols,
>> +					 max7360_keypad->keycodes, max7360_keypad->input);
>
> What if it fails? Error handling please.

Yes, forgot to return ret just below. Not adding logs as in most cases
matrix_keypad_build_keymap() will already print some logs. OK with that?

>
> Also, it looks like you are repeating what matrix_keypad_build_keymap()
> is already doing. If you pass NULL as keymap data, won't it do the right
> thing?
>

No, because matrix_keypad_parse_keymap() is using input_dev->dev.parent
and this device will not have any associated device tree node. It should
use input_dev->dev.parent->parent to get correct values.

There is a discussion ongoing about using device_set_of_node_from_dev(),
so the MFD child device reuse the node of the parent. But I tried to
avoid using it here, as I was able to come with another solution.
Discussion is in the thread of the pinctrl driver (patch #3).

Another solution would be to modify matrix_keypad_parse_keymap(),
allowing to pass a custom device. But again, I tried to avoid doing this
modification just for my own need.

> ...
>
> Thanks.

Ok with all other comments.

Thanks for your review.
Mathieu

-- 
Mathieu Dubois-Briand, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com