root/drivers/iio/proximity/cros_ec_mkbp_proximity.c
// SPDX-License-Identifier: GPL-2.0
/*
 * Driver for cros-ec proximity sensor exposed through MKBP switch
 *
 * Copyright 2021 Google LLC.
 */

#include <linux/kernel.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/notifier.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/types.h>

#include <linux/platform_data/cros_ec_commands.h>
#include <linux/platform_data/cros_ec_proto.h>

#include <linux/iio/events.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>

#include <linux/unaligned.h>

struct cros_ec_mkbp_proximity_data {
        struct cros_ec_device *ec;
        struct iio_dev *indio_dev;
        struct mutex lock;
        struct notifier_block notifier;
        int last_proximity;
        bool enabled;
};

static const struct iio_event_spec cros_ec_mkbp_proximity_events[] = {
        {
                .type = IIO_EV_TYPE_THRESH,
                .dir = IIO_EV_DIR_EITHER,
                .mask_separate = BIT(IIO_EV_INFO_ENABLE),
        },
};

static const struct iio_chan_spec cros_ec_mkbp_proximity_chan_spec[] = {
        {
                .type = IIO_PROXIMITY,
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
                .event_spec = cros_ec_mkbp_proximity_events,
                .num_event_specs = ARRAY_SIZE(cros_ec_mkbp_proximity_events),
        },
};

static int cros_ec_mkbp_proximity_parse_state(const void *data)
{
        u32 switches = get_unaligned_le32(data);

        return !!(switches & BIT(EC_MKBP_FRONT_PROXIMITY));
}

static int cros_ec_mkbp_proximity_query(struct cros_ec_device *ec_dev,
                                        int *state)
{
        DEFINE_RAW_FLEX(struct cros_ec_command, buf, data,
                        MAX(sizeof(u32), sizeof(struct ec_params_mkbp_info)));
        struct ec_params_mkbp_info *params = (struct ec_params_mkbp_info *)buf->data;
        struct cros_ec_command *msg = buf;
        u32 *switches = (u32 *)buf->data;
        size_t insize = sizeof(*switches);
        int ret;

        msg->command = EC_CMD_MKBP_INFO;
        msg->version = 1;
        msg->outsize = sizeof(*params);
        msg->insize = insize;

        params->info_type = EC_MKBP_INFO_CURRENT;
        params->event_type = EC_MKBP_EVENT_SWITCH;

        ret = cros_ec_cmd_xfer_status(ec_dev, msg);
        if (ret < 0)
                return ret;

        if (ret != insize) {
                dev_warn(ec_dev->dev, "wrong result size: %d != %zu\n", ret,
                         insize);
                return -EPROTO;
        }

        *state = cros_ec_mkbp_proximity_parse_state(switches);
        return IIO_VAL_INT;
}

static void cros_ec_mkbp_proximity_push_event(struct cros_ec_mkbp_proximity_data *data, int state)
{
        s64 timestamp;
        u64 ev;
        int dir;
        struct iio_dev *indio_dev = data->indio_dev;
        struct cros_ec_device *ec = data->ec;

        mutex_lock(&data->lock);
        if (state != data->last_proximity) {
                if (data->enabled) {
                        timestamp = ktime_to_ns(ec->last_event_time);
                        if (iio_device_get_clock(indio_dev) != CLOCK_BOOTTIME)
                                timestamp = iio_get_time_ns(indio_dev);

                        dir = state ? IIO_EV_DIR_FALLING : IIO_EV_DIR_RISING;
                        ev = IIO_UNMOD_EVENT_CODE(IIO_PROXIMITY, 0,
                                                  IIO_EV_TYPE_THRESH, dir);
                        iio_push_event(indio_dev, ev, timestamp);
                }
                data->last_proximity = state;
        }
        mutex_unlock(&data->lock);
}

static int cros_ec_mkbp_proximity_notify(struct notifier_block *nb,
                                         unsigned long queued_during_suspend,
                                         void *_ec)
{
        struct cros_ec_mkbp_proximity_data *data;
        struct cros_ec_device *ec = _ec;
        u8 event_type = ec->event_data.event_type & EC_MKBP_EVENT_TYPE_MASK;
        void *switches;
        int state;

        if (event_type == EC_MKBP_EVENT_SWITCH) {
                data = container_of(nb, struct cros_ec_mkbp_proximity_data,
                                    notifier);

                switches = &ec->event_data.data.switches;
                state = cros_ec_mkbp_proximity_parse_state(switches);
                cros_ec_mkbp_proximity_push_event(data, state);
        }

        return NOTIFY_OK;
}

static int cros_ec_mkbp_proximity_read_raw(struct iio_dev *indio_dev,
                           const struct iio_chan_spec *chan, int *val,
                           int *val2, long mask)
{
        struct cros_ec_mkbp_proximity_data *data = iio_priv(indio_dev);
        struct cros_ec_device *ec = data->ec;

        if (chan->type == IIO_PROXIMITY && mask == IIO_CHAN_INFO_RAW)
                return cros_ec_mkbp_proximity_query(ec, val);

        return -EINVAL;
}

static int cros_ec_mkbp_proximity_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 cros_ec_mkbp_proximity_data *data = iio_priv(indio_dev);

        return data->enabled;
}

static int cros_ec_mkbp_proximity_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 cros_ec_mkbp_proximity_data *data = iio_priv(indio_dev);

        mutex_lock(&data->lock);
        data->enabled = state;
        mutex_unlock(&data->lock);

        return 0;
}

static const struct iio_info cros_ec_mkbp_proximity_info = {
        .read_raw = cros_ec_mkbp_proximity_read_raw,
        .read_event_config = cros_ec_mkbp_proximity_read_event_config,
        .write_event_config = cros_ec_mkbp_proximity_write_event_config,
};

static int cros_ec_mkbp_proximity_resume(struct device *dev)
{
        struct cros_ec_mkbp_proximity_data *data = dev_get_drvdata(dev);
        struct cros_ec_device *ec = data->ec;
        int ret, state;

        ret = cros_ec_mkbp_proximity_query(ec, &state);
        if (ret < 0) {
                dev_warn(dev, "failed to fetch proximity state on resume: %d\n",
                         ret);
        } else {
                cros_ec_mkbp_proximity_push_event(data, state);
        }

        return 0;
}

static DEFINE_SIMPLE_DEV_PM_OPS(cros_ec_mkbp_proximity_pm_ops, NULL,
                                cros_ec_mkbp_proximity_resume);

static int cros_ec_mkbp_proximity_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct cros_ec_device *ec = dev_get_drvdata(dev->parent);
        struct iio_dev *indio_dev;
        struct cros_ec_mkbp_proximity_data *data;
        int ret;

        indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
        if (!indio_dev)
                return -ENOMEM;

        data = iio_priv(indio_dev);
        data->ec = ec;
        data->indio_dev = indio_dev;
        data->last_proximity = -1; /* Unknown to start */
        mutex_init(&data->lock);
        platform_set_drvdata(pdev, data);

        indio_dev->name = dev->driver->name;
        indio_dev->info = &cros_ec_mkbp_proximity_info;
        indio_dev->modes = INDIO_DIRECT_MODE;
        indio_dev->channels = cros_ec_mkbp_proximity_chan_spec;
        indio_dev->num_channels = ARRAY_SIZE(cros_ec_mkbp_proximity_chan_spec);

        ret = devm_iio_device_register(dev, indio_dev);
        if (ret)
                return ret;

        data->notifier.notifier_call = cros_ec_mkbp_proximity_notify;
        blocking_notifier_chain_register(&ec->event_notifier, &data->notifier);

        return 0;
}

static void cros_ec_mkbp_proximity_remove(struct platform_device *pdev)
{
        struct cros_ec_mkbp_proximity_data *data = platform_get_drvdata(pdev);
        struct cros_ec_device *ec = data->ec;

        blocking_notifier_chain_unregister(&ec->event_notifier,
                                           &data->notifier);
}

static const struct of_device_id cros_ec_mkbp_proximity_of_match[] = {
        { .compatible = "google,cros-ec-mkbp-proximity" },
        { }
};
MODULE_DEVICE_TABLE(of, cros_ec_mkbp_proximity_of_match);

static struct platform_driver cros_ec_mkbp_proximity_driver = {
        .driver = {
                .name = "cros-ec-mkbp-proximity",
                .of_match_table = cros_ec_mkbp_proximity_of_match,
                .pm = pm_sleep_ptr(&cros_ec_mkbp_proximity_pm_ops),
        },
        .probe = cros_ec_mkbp_proximity_probe,
        .remove = cros_ec_mkbp_proximity_remove,
};
module_platform_driver(cros_ec_mkbp_proximity_driver);

MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("ChromeOS EC MKBP proximity sensor driver");