// SPDX-License-Identifier: GPL-2.0+
/*
 * Azoteq IQS624/625 Angular Position Sensors
 *
 * Copyright (C) 2019 Jeff LaBundy <jeff@labundy.com>
 */

#include <linux/device.h>
#include <linux/iio/events.h>
#include <linux/iio/iio.h>
#include <linux/kernel.h>
#include <linux/mfd/iqs62x.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/notifier.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>

#define IQS624_POS_DEG_OUT                      0x16

#define IQS624_POS_SCALE1                       (314159 / 180)
#define IQS624_POS_SCALE2                       100000

struct iqs624_pos_private {
        struct iqs62x_core *iqs62x;
        struct iio_dev *indio_dev;
        struct notifier_block notifier;
        struct mutex lock;
        bool angle_en;
        u16 angle;
};

static int iqs624_pos_angle_en(struct iqs62x_core *iqs62x, bool angle_en)
{
        unsigned int event_mask = IQS624_HALL_UI_WHL_EVENT;

        /*
         * The IQS625 reports angular position in the form of coarse intervals,
         * so only interval change events are unmasked. Conversely, the IQS624
         * reports angular position down to one degree of resolution, so wheel
         * movement events are unmasked instead.
         */
        if (iqs62x->dev_desc->prod_num == IQS625_PROD_NUM)
                event_mask = IQS624_HALL_UI_INT_EVENT;

        return regmap_update_bits(iqs62x->regmap, IQS624_HALL_UI, event_mask,
                                  angle_en ? 0 : 0xFF);
}

static int iqs624_pos_notifier(struct notifier_block *notifier,
                               unsigned long event_flags, void *context)
{
        struct iqs62x_event_data *event_data = context;
        struct iqs624_pos_private *iqs624_pos;
        struct iqs62x_core *iqs62x;
        struct iio_dev *indio_dev;
        u16 angle = event_data->ui_data;
        s64 timestamp;
        int ret;

        iqs624_pos = container_of(notifier, struct iqs624_pos_private,
                                  notifier);
        indio_dev = iqs624_pos->indio_dev;
        timestamp = iio_get_time_ns(indio_dev);

        iqs62x = iqs624_pos->iqs62x;
        if (iqs62x->dev_desc->prod_num == IQS625_PROD_NUM)
                angle = event_data->interval;

        mutex_lock(&iqs624_pos->lock);

        if (event_flags & BIT(IQS62X_EVENT_SYS_RESET)) {
                ret = iqs624_pos_angle_en(iqs62x, iqs624_pos->angle_en);
                if (ret) {
                        dev_err(indio_dev->dev.parent,
                                "Failed to re-initialize device: %d\n", ret);
                        ret = NOTIFY_BAD;
                } else {
                        ret = NOTIFY_OK;
                }
        } else if (iqs624_pos->angle_en && (angle != iqs624_pos->angle)) {
                iio_push_event(indio_dev,
                               IIO_UNMOD_EVENT_CODE(IIO_ANGL, 0,
                                                    IIO_EV_TYPE_CHANGE,
                                                    IIO_EV_DIR_NONE),
                               timestamp);

                iqs624_pos->angle = angle;
                ret = NOTIFY_OK;
        } else {
                ret = NOTIFY_DONE;
        }

        mutex_unlock(&iqs624_pos->lock);

        return ret;
}

static void iqs624_pos_notifier_unregister(void *context)
{
        struct iqs624_pos_private *iqs624_pos = context;
        struct iio_dev *indio_dev = iqs624_pos->indio_dev;
        int ret;

        ret = blocking_notifier_chain_unregister(&iqs624_pos->iqs62x->nh,
                                                 &iqs624_pos->notifier);
        if (ret)
                dev_err(indio_dev->dev.parent,
                        "Failed to unregister notifier: %d\n", ret);
}

static int iqs624_pos_angle_get(struct iqs62x_core *iqs62x, unsigned int *val)
{
        int ret;
        __le16 val_buf;

        if (iqs62x->dev_desc->prod_num == IQS625_PROD_NUM)
                return regmap_read(iqs62x->regmap, iqs62x->dev_desc->interval,
                                   val);

        ret = regmap_raw_read(iqs62x->regmap, IQS624_POS_DEG_OUT, &val_buf,
                              sizeof(val_buf));
        if (ret)
                return ret;

        *val = le16_to_cpu(val_buf);

        return 0;
}

static int iqs624_pos_read_raw(struct iio_dev *indio_dev,
                               struct iio_chan_spec const *chan,
                               int *val, int *val2, long mask)
{
        struct iqs624_pos_private *iqs624_pos = iio_priv(indio_dev);
        struct iqs62x_core *iqs62x = iqs624_pos->iqs62x;
        unsigned int scale = 1;
        int ret;

        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                ret = iqs624_pos_angle_get(iqs62x, val);
                if (ret)
                        return ret;

                return IIO_VAL_INT;

        case IIO_CHAN_INFO_SCALE:
                if (iqs62x->dev_desc->prod_num == IQS625_PROD_NUM) {
                        ret = regmap_read(iqs62x->regmap, IQS624_INTERVAL_DIV,
                                          &scale);
                        if (ret)
                                return ret;
                }

                *val = scale * IQS624_POS_SCALE1;
                *val2 = IQS624_POS_SCALE2;
                return IIO_VAL_FRACTIONAL;

        default:
                return -EINVAL;
        }
}

static int iqs624_pos_read_event_config(struct iio_dev *indio_dev,
                                        const struct iio_chan_spec *chan,
                                        enum iio_event_type type,
                                        enum iio_event_direction dir)
{
        struct iqs624_pos_private *iqs624_pos = iio_priv(indio_dev);
        int ret;

        mutex_lock(&iqs624_pos->lock);
        ret = iqs624_pos->angle_en;
        mutex_unlock(&iqs624_pos->lock);

        return ret;
}

static int iqs624_pos_write_event_config(struct iio_dev *indio_dev,
                                         const struct iio_chan_spec *chan,
                                         enum iio_event_type type,
                                         enum iio_event_direction dir,
                                         bool state)
{
        struct iqs624_pos_private *iqs624_pos = iio_priv(indio_dev);
        struct iqs62x_core *iqs62x = iqs624_pos->iqs62x;
        unsigned int val;
        int ret;

        mutex_lock(&iqs624_pos->lock);

        ret = iqs624_pos_angle_get(iqs62x, &val);
        if (ret)
                goto err_mutex;

        ret = iqs624_pos_angle_en(iqs62x, state);
        if (ret)
                goto err_mutex;

        iqs624_pos->angle = val;
        iqs624_pos->angle_en = state;

err_mutex:
        mutex_unlock(&iqs624_pos->lock);

        return ret;
}

static const struct iio_info iqs624_pos_info = {
        .read_raw = &iqs624_pos_read_raw,
        .read_event_config = iqs624_pos_read_event_config,
        .write_event_config = iqs624_pos_write_event_config,
};

static const struct iio_event_spec iqs624_pos_events[] = {
        {
                .type = IIO_EV_TYPE_CHANGE,
                .dir = IIO_EV_DIR_NONE,
                .mask_separate = BIT(IIO_EV_INFO_ENABLE),
        },
};

static const struct iio_chan_spec iqs624_pos_channels[] = {
        {
                .type = IIO_ANGL,
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
                                      BIT(IIO_CHAN_INFO_SCALE),
                .event_spec = iqs624_pos_events,
                .num_event_specs = ARRAY_SIZE(iqs624_pos_events),
        },
};

static int iqs624_pos_probe(struct platform_device *pdev)
{
        struct iqs62x_core *iqs62x = dev_get_drvdata(pdev->dev.parent);
        struct iqs624_pos_private *iqs624_pos;
        struct iio_dev *indio_dev;
        int ret;

        indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*iqs624_pos));
        if (!indio_dev)
                return -ENOMEM;

        iqs624_pos = iio_priv(indio_dev);
        iqs624_pos->iqs62x = iqs62x;
        iqs624_pos->indio_dev = indio_dev;

        indio_dev->modes = INDIO_DIRECT_MODE;
        indio_dev->channels = iqs624_pos_channels;
        indio_dev->num_channels = ARRAY_SIZE(iqs624_pos_channels);
        indio_dev->name = iqs62x->dev_desc->dev_name;
        indio_dev->info = &iqs624_pos_info;

        mutex_init(&iqs624_pos->lock);

        iqs624_pos->notifier.notifier_call = iqs624_pos_notifier;
        ret = blocking_notifier_chain_register(&iqs624_pos->iqs62x->nh,
                                               &iqs624_pos->notifier);
        if (ret) {
                dev_err(&pdev->dev, "Failed to register notifier: %d\n", ret);
                return ret;
        }

        ret = devm_add_action_or_reset(&pdev->dev,
                                       iqs624_pos_notifier_unregister,
                                       iqs624_pos);
        if (ret)
                return ret;

        return devm_iio_device_register(&pdev->dev, indio_dev);
}

static struct platform_driver iqs624_pos_platform_driver = {
        .driver = {
                .name = "iqs624-pos",
        },
        .probe = iqs624_pos_probe,
};
module_platform_driver(iqs624_pos_platform_driver);

MODULE_AUTHOR("Jeff LaBundy <jeff@labundy.com>");
MODULE_DESCRIPTION("Azoteq IQS624/625 Angular Position Sensors");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:iqs624-pos");