[PATCH v14 09/10] input: misc: Add support for MAX7360 rotary

Mathieu Dubois-Briand
2025-08-24T11:58:28Z

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

Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
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 | 192 ++++++++++++++++++++++++++++++++++++
3 files changed, 203 insertions(+)

diff --git a/drivers/input/misc/Kconfig b/drivers/input/misc/Kconfig
index 0fb21c99a5e3..d604aad90a89 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 d468c8140b93..ac45cb9b5c99 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..385831ef34b6
--- /dev/null
+++ b/drivers/input/misc/max7360-rotary.c
@@ -0,0 +1,192 @@
+// 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>
+
+#define MAX7360_ROTARY_DEFAULT_STEPS 24
+
+struct max7360_rotary {
+ struct input_dev *input;
+ struct regmap *regmap;
+ unsigned int debounce_ms;
+
+ unsigned int pos;
+
+ u32 steps;
+ u32 axis;
+ bool relative_axis;
+ bool rollover;
+};
+
+static void max7360_rotary_report_event(struct max7360_rotary *max7360_rotary, int steps)
+{
+ if (max7360_rotary->relative_axis) {
+ input_report_rel(max7360_rotary->input, max7360_rotary->axis, steps);
+ } else {
+ int pos = max7360_rotary->pos;
+ int maxval = max7360_rotary->steps;
+
+ /*
+ * Add steps to the position.
+ * Make sure added steps are always in ]-maxval; maxval[
+ * interval, so (pos + maxval) is always >= 0.
+ * Then set back pos to the [0; maxval[ interval.
+ */
+ pos += steps % maxval;
+ if (max7360_rotary->rollover)
+ pos = (pos + maxval) % maxval;
+ else
+ pos = clamp(pos, 0, maxval - 1);
+
+ max7360_rotary->pos = pos;
+ input_report_abs(max7360_rotary->input, max7360_rotary->axis, max7360_rotary->pos);
+ }
+
+ input_sync(max7360_rotary->input);
+}
+
+static irqreturn_t max7360_rotary_irq(int irq, void *data)
+{
+ struct max7360_rotary *max7360_rotary = data;
+ struct device *dev = max7360_rotary->input->dev.parent;
+ unsigned int val;
+ int error;
+
+ error = regmap_read(max7360_rotary->regmap, MAX7360_REG_RTR_CNT, &val);
+ if (error < 0) {
+ dev_err(dev, "Failed to read rotary counter\n");
+ return IRQ_NONE;
+ }
+
+ if (val == 0)
+ return IRQ_NONE;
+
+ max7360_rotary_report_event(max7360_rotary, sign_extend32(val, 7));
+
+ return IRQ_HANDLED;
+}
+
+static int max7360_rotary_hw_init(struct max7360_rotary *max7360_rotary)
+{
+ struct device *dev = max7360_rotary->input->dev.parent;
+ int val;
+ int error;
+
+ val = FIELD_PREP(MAX7360_ROT_DEBOUNCE, max7360_rotary->debounce_ms) |
+ FIELD_PREP(MAX7360_ROT_INTCNT, 1) | MAX7360_ROT_INTCNT_DLY;
+ error = regmap_write(max7360_rotary->regmap, MAX7360_REG_RTRCFG, val);
+ if (error)
+ dev_err(dev, "Failed to set max7360 rotary encoder configuration\n");
+
+ return error;
+}
+
+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 error;
+
+ regmap = dev_get_regmap(dev->parent, NULL);
+ if (!regmap)
+ return 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);
+ max7360_rotary->rollover = device_property_read_bool(dev->parent,
+ "rotary-encoder,rollover");
+ max7360_rotary->relative_axis =
+ device_property_read_bool(dev->parent, "rotary-encoder,relative-axis");
+
+ error = device_property_read_u32(dev->parent, "rotary-encoder,steps",
+ &max7360_rotary->steps);
+ if (error)
+ max7360_rotary->steps = MAX7360_ROTARY_DEFAULT_STEPS;
+
+ 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;
+
+ if (max7360_rotary->relative_axis)
+ input_set_capability(input, EV_REL, max7360_rotary->axis);
+ else
+ input_set_abs_params(input, max7360_rotary->axis, 0, max7360_rotary->steps, 0, 1);
+
+ error = devm_request_threaded_irq(dev, irq, NULL, max7360_rotary_irq,
+ IRQF_ONESHOT | IRQF_SHARED,
+ "max7360-rotary", max7360_rotary);
+ if (error)
+ return dev_err_probe(dev, error, "Failed to register interrupt\n");
+
+ error = input_register_device(input);
+ if (error)
+ return dev_err_probe(dev, error, "Could not register input device\n");
+
+ error = max7360_rotary_hw_init(max7360_rotary);
+ if (error)
+ return dev_err_probe(dev, error, "Failed to initialize max7360 rotary\n");
+
+ device_init_wakeup(dev, true);
+ error = dev_pm_set_wake_irq(dev, irq);
+ if (error)
+ dev_warn(dev, "Failed to set up wakeup irq: %d\n", error);
+
+ return 0;
+}
+
+static void max7360_rotary_remove(struct platform_device *pdev)
+{
+ dev_pm_clear_wake_irq(&pdev->dev);
+ device_init_wakeup(&pdev->dev, false);
+}
+
+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