// 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");