[PATCH v6 11/12] input: misc: Add support for MAX7360 rotary

[Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>]

Add driver for Maxim Integrated MAX7360 rotary encoder controller,
supporting a single rotary switch.

Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
---
 drivers/input/misc/Kconfig          |  10 +++
 drivers/input/misc/Makefile         |   1 +
 drivers/input/misc/max7360-rotary.c | 148 ++++++++++++++++++++++++++++++++++++
 3 files changed, 159 insertions(+)

diff --git a/drivers/input/misc/Kconfig b/drivers/input/misc/Kconfig
index f5496ca0c0d2..0bc9d121c984 100644
--- a/drivers/input/misc/Kconfig
+++ b/drivers/input/misc/Kconfig
@@ -230,6 +230,16 @@ config INPUT_M68K_BEEP
 	tristate "M68k Beeper support"
 	depends on M68K
 
+config INPUT_MAX7360_ROTARY
+	tristate "Maxim MAX7360 Rotary Encoder"
+	depends on MFD_MAX7360
+	help
+	  If you say yes here you get support for the rotary encoder on the
+	  Maxim MAX7360 I/O Expander.
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called max7360_rotary.
+
 config INPUT_MAX77650_ONKEY
 	tristate "Maxim MAX77650 ONKEY support"
 	depends on MFD_MAX77650
diff --git a/drivers/input/misc/Makefile b/drivers/input/misc/Makefile
index 6d91804d0a6f..c454fba3a3ae 100644
--- a/drivers/input/misc/Makefile
+++ b/drivers/input/misc/Makefile
@@ -51,6 +51,7 @@ obj-$(CONFIG_INPUT_IQS7222)		+= iqs7222.o
 obj-$(CONFIG_INPUT_KEYSPAN_REMOTE)	+= keyspan_remote.o
 obj-$(CONFIG_INPUT_KXTJ9)		+= kxtj9.o
 obj-$(CONFIG_INPUT_M68K_BEEP)		+= m68kspkr.o
+obj-$(CONFIG_INPUT_MAX7360_ROTARY)	+= max7360-rotary.o
 obj-$(CONFIG_INPUT_MAX77650_ONKEY)	+= max77650-onkey.o
 obj-$(CONFIG_INPUT_MAX77693_HAPTIC)	+= max77693-haptic.o
 obj-$(CONFIG_INPUT_MAX8925_ONKEY)	+= max8925_onkey.o
diff --git a/drivers/input/misc/max7360-rotary.c b/drivers/input/misc/max7360-rotary.c
new file mode 100644
index 000000000000..c9630e79730a
--- /dev/null
+++ b/drivers/input/misc/max7360-rotary.c
@@ -0,0 +1,148 @@
+// 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/device/devres.h>
+#include <linux/dev_printk.h>
+#include <linux/init.h>
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/mfd/max7360.h>
+#include <linux/property.h>
+#include <linux/platform_device.h>
+#include <linux/pm_wakeirq.h>
+#include <linux/regmap.h>
+#include <linux/types.h>
+
+struct max7360_rotary {
+	u32 axis;
+	struct input_dev *input;
+	unsigned int debounce_ms;
+	struct regmap *regmap;
+};
+
+static irqreturn_t max7360_rotary_irq(int irq, void *data)
+{
+	struct max7360_rotary *max7360_rotary = data;
+	unsigned int val;
+	int ret;
+
+	ret = regmap_read(max7360_rotary->regmap, MAX7360_REG_RTR_CNT, &val);
+	if (ret < 0) {
+		dev_err(&max7360_rotary->input->dev,
+			"Failed to read rotary counter\n");
+		return IRQ_NONE;
+	}
+
+	if (val == 0) {
+		dev_dbg(&max7360_rotary->input->dev,
+			"Got a spurious interrupt\n");
+
+		return IRQ_NONE;
+	}
+
+	input_report_rel(max7360_rotary->input, max7360_rotary->axis, sign_extend32(val, 7));
+	input_sync(max7360_rotary->input);
+
+	return IRQ_HANDLED;
+}
+
+static int max7360_rotary_hw_init(struct max7360_rotary *max7360_rotary)
+{
+	int val;
+	int ret;
+
+	val = FIELD_PREP(MAX7360_ROT_DEBOUNCE, max7360_rotary->debounce_ms) |
+		FIELD_PREP(MAX7360_ROT_INTCNT, 1) | MAX7360_ROT_INTCNT_DLY;
+	ret = regmap_write(max7360_rotary->regmap, MAX7360_REG_RTRCFG, val);
+	if (ret)
+		dev_err(&max7360_rotary->input->dev,
+			"Failed to set max7360 rotary encoder configuration\n");
+
+	return ret;
+}
+
+static int max7360_rotary_probe(struct platform_device *pdev)
+{
+	struct max7360_rotary *max7360_rotary;
+	struct device *dev = &pdev->dev;
+	struct input_dev *input;
+	struct regmap *regmap;
+	int irq;
+	int ret;
+
+	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), "inti");
+	if (irq < 0)
+		return dev_err_probe(dev, irq, "Failed to get IRQ\n");
+
+	max7360_rotary = devm_kzalloc(dev, sizeof(*max7360_rotary), GFP_KERNEL);
+	if (!max7360_rotary)
+		return -ENOMEM;
+
+	max7360_rotary->regmap = regmap;
+	device_property_read_u32(dev->parent, "linux,axis", &max7360_rotary->axis);
+	device_property_read_u32(dev->parent, "rotary-debounce-delay-ms",
+				 &max7360_rotary->debounce_ms);
+	if (max7360_rotary->debounce_ms > MAX7360_ROT_DEBOUNCE_MAX)
+		return dev_err_probe(dev, -EINVAL, "Invalid debounce timing: %u\n",
+				     max7360_rotary->debounce_ms);
+
+	input = devm_input_allocate_device(dev);
+	if (!input)
+		return -ENOMEM;
+
+	max7360_rotary->input = input;
+
+	input->id.bustype = BUS_I2C;
+	input->name = pdev->name;
+	input->dev.parent = dev;
+
+	input_set_capability(input, EV_REL, max7360_rotary->axis);
+
+	ret = devm_request_threaded_irq(dev, irq, NULL, max7360_rotary_irq,
+					IRQF_ONESHOT | IRQF_SHARED,
+					"max7360-rotary", max7360_rotary);
+	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_rotary_hw_init(max7360_rotary);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to initialize max7360 rotary\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_rotary_remove(struct platform_device *pdev)
+{
+	dev_pm_clear_wake_irq(&pdev->dev);
+}
+
+static struct platform_driver max7360_rotary_driver = {
+	.driver = {
+		.name	= "max7360-rotary",
+	},
+	.probe		= max7360_rotary_probe,
+	.remove		= max7360_rotary_remove,
+};
+module_platform_driver(max7360_rotary_driver);
+
+MODULE_DESCRIPTION("MAX7360 Rotary driver");
+MODULE_AUTHOR("Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>");
+MODULE_LICENSE("GPL");

-- 
2.39.5