// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright 2021 Google LLC.
 *
 * Common part of most Semtech SAR sensor.
 */

#include <linux/bitops.h>
#include <linux/byteorder/generic.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/export.h>
#include <linux/interrupt.h>
#include <linux/irqreturn.h>
#include <linux/i2c.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/regmap.h>
#include <linux/regulator/consumer.h>
#include <vdso/bits.h>

#include <linux/iio/buffer.h>
#include <linux/iio/events.h>
#include <linux/iio/iio.h>
#include <linux/iio/trigger.h>
#include <linux/iio/triggered_buffer.h>
#include <linux/iio/trigger_consumer.h>

#include "sx_common.h"

/* All Semtech SAR sensors have IRQ bit in the same order. */
#define   SX_COMMON_CONVDONE_IRQ                        BIT(0)
#define   SX_COMMON_FAR_IRQ                             BIT(2)
#define   SX_COMMON_CLOSE_IRQ                           BIT(3)

const struct iio_event_spec sx_common_events[3] = {
        {
                .type = IIO_EV_TYPE_THRESH,
                .dir = IIO_EV_DIR_RISING,
                .mask_shared_by_all = BIT(IIO_EV_INFO_PERIOD),
        },
        {
                .type = IIO_EV_TYPE_THRESH,
                .dir = IIO_EV_DIR_FALLING,
                .mask_shared_by_all = BIT(IIO_EV_INFO_PERIOD),
        },
        {
                .type = IIO_EV_TYPE_THRESH,
                .dir = IIO_EV_DIR_EITHER,
                .mask_separate = BIT(IIO_EV_INFO_ENABLE) |
                                 BIT(IIO_EV_INFO_HYSTERESIS) |
                                 BIT(IIO_EV_INFO_VALUE),
        },
};
EXPORT_SYMBOL_NS_GPL(sx_common_events, "SEMTECH_PROX");

static irqreturn_t sx_common_irq_handler(int irq, void *private)
{
        struct iio_dev *indio_dev = private;
        struct sx_common_data *data = iio_priv(indio_dev);

        if (data->trigger_enabled)
                iio_trigger_poll(data->trig);

        /*
         * Even if no event is enabled, we need to wake the thread to clear the
         * interrupt state by reading SX_COMMON_REG_IRQ_SRC.
         * It is not possible to do that here because regmap_read takes a mutex.
         */
        return IRQ_WAKE_THREAD;
}

static void sx_common_push_events(struct iio_dev *indio_dev)
{
        int ret;
        unsigned int val, chan;
        struct sx_common_data *data = iio_priv(indio_dev);
        s64 timestamp = iio_get_time_ns(indio_dev);
        unsigned long prox_changed;

        /* Read proximity state on all channels */
        ret = regmap_read(data->regmap, data->chip_info->reg_stat, &val);
        if (ret) {
                dev_err(&data->client->dev, "i2c transfer error in irq\n");
                return;
        }

        val >>= data->chip_info->stat_offset;

        /*
         * Only iterate over channels with changes on proximity status that have
         * events enabled.
         */
        prox_changed = (data->chan_prox_stat ^ val) & data->chan_event;

        for_each_set_bit(chan, &prox_changed, data->chip_info->num_channels) {
                int dir;
                u64 ev;

                dir = (val & BIT(chan)) ? IIO_EV_DIR_FALLING : IIO_EV_DIR_RISING;
                ev = IIO_UNMOD_EVENT_CODE(IIO_PROXIMITY, chan,
                                          IIO_EV_TYPE_THRESH, dir);

                iio_push_event(indio_dev, ev, timestamp);
        }
        data->chan_prox_stat = val;
}

static int sx_common_enable_irq(struct sx_common_data *data, unsigned int irq)
{
        if (!data->client->irq)
                return 0;
        return regmap_set_bits(data->regmap, data->chip_info->reg_irq_msk,
                               irq << data->chip_info->irq_msk_offset);
}

static int sx_common_disable_irq(struct sx_common_data *data, unsigned int irq)
{
        if (!data->client->irq)
                return 0;
        return regmap_clear_bits(data->regmap, data->chip_info->reg_irq_msk,
                                 irq << data->chip_info->irq_msk_offset);
}

static int sx_common_update_chan_en(struct sx_common_data *data,
                                    unsigned long chan_read,
                                    unsigned long chan_event)
{
        int ret;
        unsigned long channels = chan_read | chan_event;

        if ((data->chan_read | data->chan_event) != channels) {
                ret = regmap_update_bits(data->regmap,
                                         data->chip_info->reg_enable_chan,
                                         data->chip_info->mask_enable_chan,
                                         channels);
                if (ret)
                        return ret;
        }
        data->chan_read = chan_read;
        data->chan_event = chan_event;
        return 0;
}

static int sx_common_get_read_channel(struct sx_common_data *data, int channel)
{
        return sx_common_update_chan_en(data, data->chan_read | BIT(channel),
                                     data->chan_event);
}

static int sx_common_put_read_channel(struct sx_common_data *data, int channel)
{
        return sx_common_update_chan_en(data, data->chan_read & ~BIT(channel),
                                     data->chan_event);
}

static int sx_common_get_event_channel(struct sx_common_data *data, int channel)
{
        return sx_common_update_chan_en(data, data->chan_read,
                                     data->chan_event | BIT(channel));
}

static int sx_common_put_event_channel(struct sx_common_data *data, int channel)
{
        return sx_common_update_chan_en(data, data->chan_read,
                                     data->chan_event & ~BIT(channel));
}

/**
 * sx_common_read_proximity() - Read raw proximity value.
 * @data:       Internal data
 * @chan:       Channel to read
 * @val:        pointer to return read value.
 *
 * Request a conversion, wait for the sensor to be ready and
 * return the raw proximity value.
 */
int sx_common_read_proximity(struct sx_common_data *data,
                             const struct iio_chan_spec *chan, int *val)
{
        int ret;
        __be16 rawval;

        mutex_lock(&data->mutex);

        ret = sx_common_get_read_channel(data, chan->channel);
        if (ret)
                goto out;

        ret = sx_common_enable_irq(data, SX_COMMON_CONVDONE_IRQ);
        if (ret)
                goto out_put_channel;

        mutex_unlock(&data->mutex);

        if (data->client->irq) {
                ret = wait_for_completion_interruptible(&data->completion);
                reinit_completion(&data->completion);
        } else {
                ret = data->chip_info->ops.wait_for_sample(data);
        }

        mutex_lock(&data->mutex);

        if (ret)
                goto out_disable_irq;

        ret = data->chip_info->ops.read_prox_data(data, chan, &rawval);
        if (ret)
                goto out_disable_irq;

        *val = sign_extend32(be16_to_cpu(rawval), chan->scan_type.realbits - 1);

        ret = sx_common_disable_irq(data, SX_COMMON_CONVDONE_IRQ);
        if (ret)
                goto out_put_channel;

        ret = sx_common_put_read_channel(data, chan->channel);
        if (ret)
                goto out;

        mutex_unlock(&data->mutex);

        return IIO_VAL_INT;

out_disable_irq:
        sx_common_disable_irq(data, SX_COMMON_CONVDONE_IRQ);
out_put_channel:
        sx_common_put_read_channel(data, chan->channel);
out:
        mutex_unlock(&data->mutex);

        return ret;
}
EXPORT_SYMBOL_NS_GPL(sx_common_read_proximity, "SEMTECH_PROX");

/**
 * sx_common_read_event_config() - Configure event setting.
 * @indio_dev:  iio device object
 * @chan:       Channel to read
 * @type:       Type of event (unused)
 * @dir:        Direction of event (unused)
 *
 * return if the given channel is used for event gathering.
 */
int sx_common_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 sx_common_data *data = iio_priv(indio_dev);

        return !!(data->chan_event & BIT(chan->channel));
}
EXPORT_SYMBOL_NS_GPL(sx_common_read_event_config, "SEMTECH_PROX");

/**
 * sx_common_write_event_config() - Configure event setting.
 * @indio_dev:  iio device object
 * @chan:       Channel to enable
 * @type:       Type of event (unused)
 * @dir:        Direction of event (unused)
 * @state:      State of the event.
 *
 * Enable/Disable event on a given channel.
 */
int sx_common_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 sx_common_data *data = iio_priv(indio_dev);
        unsigned int eventirq = SX_COMMON_FAR_IRQ | SX_COMMON_CLOSE_IRQ;
        int ret;

        /* If the state hasn't changed, there's nothing to do. */
        if (!!(data->chan_event & BIT(chan->channel)) == state)
                return 0;

        mutex_lock(&data->mutex);
        if (state) {
                ret = sx_common_get_event_channel(data, chan->channel);
                if (ret)
                        goto out_unlock;
                if (!(data->chan_event & ~BIT(chan->channel))) {
                        ret = sx_common_enable_irq(data, eventirq);
                        if (ret)
                                sx_common_put_event_channel(data, chan->channel);
                }
        } else {
                ret = sx_common_put_event_channel(data, chan->channel);
                if (ret)
                        goto out_unlock;
                if (!data->chan_event) {
                        ret = sx_common_disable_irq(data, eventirq);
                        if (ret)
                                sx_common_get_event_channel(data, chan->channel);
                }
        }

out_unlock:
        mutex_unlock(&data->mutex);
        return ret;
}
EXPORT_SYMBOL_NS_GPL(sx_common_write_event_config, "SEMTECH_PROX");

static int sx_common_set_trigger_state(struct iio_trigger *trig, bool state)
{
        struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
        struct sx_common_data *data = iio_priv(indio_dev);
        int ret = 0;

        mutex_lock(&data->mutex);

        if (state)
                ret = sx_common_enable_irq(data, SX_COMMON_CONVDONE_IRQ);
        else if (!data->chan_read)
                ret = sx_common_disable_irq(data, SX_COMMON_CONVDONE_IRQ);
        if (ret)
                goto out;

        data->trigger_enabled = state;

out:
        mutex_unlock(&data->mutex);

        return ret;
}

static const struct iio_trigger_ops sx_common_trigger_ops = {
        .set_trigger_state = sx_common_set_trigger_state,
};

static irqreturn_t sx_common_irq_thread_handler(int irq, void *private)
{
        struct iio_dev *indio_dev = private;
        struct sx_common_data *data = iio_priv(indio_dev);
        int ret;
        unsigned int val;

        mutex_lock(&data->mutex);

        ret = regmap_read(data->regmap, SX_COMMON_REG_IRQ_SRC, &val);
        if (ret) {
                dev_err(&data->client->dev, "i2c transfer error in irq\n");
                goto out;
        }

        if (val & ((SX_COMMON_FAR_IRQ | SX_COMMON_CLOSE_IRQ) << data->chip_info->irq_msk_offset))
                sx_common_push_events(indio_dev);

        if (val & (SX_COMMON_CONVDONE_IRQ << data->chip_info->irq_msk_offset))
                complete(&data->completion);

out:
        mutex_unlock(&data->mutex);

        return IRQ_HANDLED;
}

static irqreturn_t sx_common_trigger_handler(int irq, void *private)
{
        struct iio_poll_func *pf = private;
        struct iio_dev *indio_dev = pf->indio_dev;
        struct sx_common_data *data = iio_priv(indio_dev);
        __be16 val;
        int bit, ret, i = 0;

        mutex_lock(&data->mutex);

        iio_for_each_active_channel(indio_dev, bit) {
                ret = data->chip_info->ops.read_prox_data(data,
                                                     &indio_dev->channels[bit],
                                                     &val);
                if (ret)
                        goto out;

                data->buffer.channels[i++] = val;
        }

        iio_push_to_buffers_with_ts(indio_dev, &data->buffer,
                                    sizeof(data->buffer), pf->timestamp);

out:
        mutex_unlock(&data->mutex);

        iio_trigger_notify_done(indio_dev->trig);

        return IRQ_HANDLED;
}

static int sx_common_buffer_preenable(struct iio_dev *indio_dev)
{
        struct sx_common_data *data = iio_priv(indio_dev);
        unsigned long channels = 0;
        int bit, ret;

        mutex_lock(&data->mutex);
        iio_for_each_active_channel(indio_dev, bit)
                __set_bit(indio_dev->channels[bit].channel, &channels);

        ret = sx_common_update_chan_en(data, channels, data->chan_event);
        mutex_unlock(&data->mutex);
        return ret;
}

static int sx_common_buffer_postdisable(struct iio_dev *indio_dev)
{
        struct sx_common_data *data = iio_priv(indio_dev);
        int ret;

        mutex_lock(&data->mutex);
        ret = sx_common_update_chan_en(data, 0, data->chan_event);
        mutex_unlock(&data->mutex);
        return ret;
}

static const struct iio_buffer_setup_ops sx_common_buffer_setup_ops = {
        .preenable = sx_common_buffer_preenable,
        .postdisable = sx_common_buffer_postdisable,
};

#define SX_COMMON_SOFT_RESET                            0xde

static int sx_common_init_device(struct device *dev, struct iio_dev *indio_dev)
{
        struct sx_common_data *data = iio_priv(indio_dev);
        struct sx_common_reg_default tmp;
        const struct sx_common_reg_default *initval;
        int ret;
        unsigned int i, val;

        ret = regmap_write(data->regmap, data->chip_info->reg_reset,
                           SX_COMMON_SOFT_RESET);
        if (ret)
                return ret;

        usleep_range(1000, 2000); /* power-up time is ~1ms. */

        /* Clear reset interrupt state by reading SX_COMMON_REG_IRQ_SRC. */
        ret = regmap_read(data->regmap, SX_COMMON_REG_IRQ_SRC, &val);
        if (ret)
                return ret;

        /* Program defaults from constant or BIOS. */
        for (i = 0; i < data->chip_info->num_default_regs; i++) {
                initval = data->chip_info->ops.get_default_reg(dev, i, &tmp);
                ret = regmap_write(data->regmap, initval->reg, initval->def);
                if (ret)
                        return ret;
        }

        return data->chip_info->ops.init_compensation(indio_dev);
}

/**
 * sx_common_probe() - Common setup for Semtech SAR sensor
 * @client:             I2C client object
 * @chip_info:          Semtech sensor chip information.
 * @regmap_config:      Sensor registers map configuration.
 */
int sx_common_probe(struct i2c_client *client,
                    const struct sx_common_chip_info *chip_info,
                    const struct regmap_config *regmap_config)
{
        static const char * const regulator_names[] = { "vdd", "svdd" };
        struct device *dev = &client->dev;
        struct iio_dev *indio_dev;
        struct sx_common_data *data;
        int ret;

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

        data = iio_priv(indio_dev);

        data->chip_info = chip_info;
        data->client = client;
        mutex_init(&data->mutex);
        init_completion(&data->completion);

        data->regmap = devm_regmap_init_i2c(client, regmap_config);
        if (IS_ERR(data->regmap))
                return dev_err_probe(dev, PTR_ERR(data->regmap),
                                     "Could init register map\n");

        ret = devm_regulator_bulk_get_enable(dev, ARRAY_SIZE(regulator_names),
                                             regulator_names);
        if (ret)
                return dev_err_probe(dev, ret, "Unable to get regulators\n");

        /* Must wait for Tpor time after initial power up */
        usleep_range(1000, 1100);

        ret = data->chip_info->ops.check_whoami(dev, indio_dev);
        if (ret)
                return dev_err_probe(dev, ret, "error reading WHOAMI\n");

        indio_dev->modes = INDIO_DIRECT_MODE;

        indio_dev->channels =  data->chip_info->iio_channels;
        indio_dev->num_channels = data->chip_info->num_iio_channels;
        indio_dev->info = &data->chip_info->iio_info;

        i2c_set_clientdata(client, indio_dev);

        ret = sx_common_init_device(dev, indio_dev);
        if (ret)
                return dev_err_probe(dev, ret, "Unable to initialize sensor\n");

        if (client->irq) {
                ret = devm_request_threaded_irq(dev, client->irq,
                                                sx_common_irq_handler,
                                                sx_common_irq_thread_handler,
                                                IRQF_ONESHOT,
                                                "sx_event", indio_dev);
                if (ret)
                        return dev_err_probe(dev, ret, "No IRQ\n");

                data->trig = devm_iio_trigger_alloc(dev, "%s-dev%d",
                                                    indio_dev->name,
                                                    iio_device_id(indio_dev));
                if (!data->trig)
                        return -ENOMEM;

                data->trig->ops = &sx_common_trigger_ops;
                iio_trigger_set_drvdata(data->trig, indio_dev);

                ret = devm_iio_trigger_register(dev, data->trig);
                if (ret)
                        return ret;
        }

        ret = devm_iio_triggered_buffer_setup(dev, indio_dev,
                                              iio_pollfunc_store_time,
                                              sx_common_trigger_handler,
                                              &sx_common_buffer_setup_ops);
        if (ret)
                return ret;

        return devm_iio_device_register(dev, indio_dev);
}
EXPORT_SYMBOL_NS_GPL(sx_common_probe, "SEMTECH_PROX");

MODULE_AUTHOR("Gwendal Grignou <gwendal@chromium.org>");
MODULE_DESCRIPTION("Common functions and structures for Semtech sensor");
MODULE_LICENSE("GPL v2");