// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * AD7291 8-Channel, I2C, 12-Bit SAR ADC with Temperature Sensor
 *
 * Copyright 2010-2011 Analog Devices Inc.
 */

#include <linux/device.h>
#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/regulator/consumer.h>
#include <linux/slab.h>
#include <linux/sysfs.h>

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

/*
 * Simplified handling
 *
 * If no events enabled - single polled channel read
 * If event enabled direct reads disable unless channel
 * is in the read mask.
 *
 * The noise-delayed bit as per datasheet suggestion is always enabled.
 */

/*
 * AD7291 registers definition
 */
#define AD7291_COMMAND                  0x00
#define AD7291_VOLTAGE                  0x01
#define AD7291_T_SENSE                  0x02
#define AD7291_T_AVERAGE                0x03
#define AD7291_DATA_HIGH(x)             ((x) * 3 + 0x4)
#define AD7291_DATA_LOW(x)              ((x) * 3 + 0x5)
#define AD7291_HYST(x)                  ((x) * 3 + 0x6)
#define AD7291_VOLTAGE_ALERT_STATUS     0x1F
#define AD7291_T_ALERT_STATUS           0x20

#define AD7291_BITS                     12
#define AD7291_VOLTAGE_LIMIT_COUNT      8


/*
 * AD7291 command
 */
#define AD7291_AUTOCYCLE                BIT(0)
#define AD7291_RESET                    BIT(1)
#define AD7291_ALERT_CLEAR              BIT(2)
#define AD7291_ALERT_POLARITY           BIT(3)
#define AD7291_EXT_REF                  BIT(4)
#define AD7291_NOISE_DELAY              BIT(5)
#define AD7291_T_SENSE_MASK             BIT(7)
#define AD7291_VOLTAGE_MASK             GENMASK(15, 8)
#define AD7291_VOLTAGE_OFFSET           8

/*
 * AD7291 value masks
 */
#define AD7291_VALUE_MASK               GENMASK(11, 0)

/*
 * AD7291 alert register bits
 */
#define AD7291_T_LOW                    BIT(0)
#define AD7291_T_HIGH                   BIT(1)
#define AD7291_T_AVG_LOW                BIT(2)
#define AD7291_T_AVG_HIGH               BIT(3)
#define AD7291_V_LOW(x)                 BIT((x) * 2)
#define AD7291_V_HIGH(x)                BIT((x) * 2 + 1)


struct ad7291_chip_info {
        struct i2c_client       *client;
        struct regulator        *reg;
        u16                     command;
        u16                     c_mask; /* Active voltage channels for events */
        struct mutex            state_lock;
};

static int ad7291_i2c_read(struct ad7291_chip_info *chip, u8 reg, u16 *data)
{
        struct i2c_client *client = chip->client;
        int ret = 0;

        ret = i2c_smbus_read_word_swapped(client, reg);
        if (ret < 0) {
                dev_err(&client->dev, "I2C read error\n");
                return ret;
        }

        *data = ret;

        return 0;
}

static int ad7291_i2c_write(struct ad7291_chip_info *chip, u8 reg, u16 data)
{
        return i2c_smbus_write_word_swapped(chip->client, reg, data);
}

static irqreturn_t ad7291_event_handler(int irq, void *private)
{
        struct iio_dev *indio_dev = private;
        struct ad7291_chip_info *chip = iio_priv(private);
        u16 t_status, v_status;
        u16 command;
        int i;
        s64 timestamp = iio_get_time_ns(indio_dev);

        if (ad7291_i2c_read(chip, AD7291_T_ALERT_STATUS, &t_status))
                return IRQ_HANDLED;

        if (ad7291_i2c_read(chip, AD7291_VOLTAGE_ALERT_STATUS, &v_status))
                return IRQ_HANDLED;

        if (!(t_status || v_status))
                return IRQ_HANDLED;

        command = chip->command | AD7291_ALERT_CLEAR;
        ad7291_i2c_write(chip, AD7291_COMMAND, command);

        command = chip->command & ~AD7291_ALERT_CLEAR;
        ad7291_i2c_write(chip, AD7291_COMMAND, command);

        /* For now treat t_sense and t_sense_average the same */
        if ((t_status & AD7291_T_LOW) || (t_status & AD7291_T_AVG_LOW))
                iio_push_event(indio_dev,
                               IIO_UNMOD_EVENT_CODE(IIO_TEMP,
                                                    0,
                                                    IIO_EV_TYPE_THRESH,
                                                    IIO_EV_DIR_FALLING),
                               timestamp);
        if ((t_status & AD7291_T_HIGH) || (t_status & AD7291_T_AVG_HIGH))
                iio_push_event(indio_dev,
                               IIO_UNMOD_EVENT_CODE(IIO_TEMP,
                                                    0,
                                                    IIO_EV_TYPE_THRESH,
                                                    IIO_EV_DIR_RISING),
                               timestamp);

        for (i = 0; i < AD7291_VOLTAGE_LIMIT_COUNT; i++) {
                if (v_status & AD7291_V_LOW(i))
                        iio_push_event(indio_dev,
                                       IIO_UNMOD_EVENT_CODE(IIO_VOLTAGE,
                                                            i,
                                                            IIO_EV_TYPE_THRESH,
                                                            IIO_EV_DIR_FALLING),
                                       timestamp);
                if (v_status & AD7291_V_HIGH(i))
                        iio_push_event(indio_dev,
                                       IIO_UNMOD_EVENT_CODE(IIO_VOLTAGE,
                                                            i,
                                                            IIO_EV_TYPE_THRESH,
                                                            IIO_EV_DIR_RISING),
                                       timestamp);
        }

        return IRQ_HANDLED;
}

static unsigned int ad7291_threshold_reg(const struct iio_chan_spec *chan,
                                         enum iio_event_direction dir,
                                         enum iio_event_info info)
{
        unsigned int offset;

        switch (chan->type) {
        case IIO_VOLTAGE:
                offset = chan->channel;
                break;
        case IIO_TEMP:
                offset = AD7291_VOLTAGE_OFFSET;
                break;
        default:
                return 0;
        }

        switch (info) {
        case IIO_EV_INFO_VALUE:
                if (dir == IIO_EV_DIR_FALLING)
                        return AD7291_DATA_HIGH(offset);
                else
                        return AD7291_DATA_LOW(offset);
        case IIO_EV_INFO_HYSTERESIS:
                return AD7291_HYST(offset);
        default:
                break;
        }
        return 0;
}

static int ad7291_read_event_value(struct iio_dev *indio_dev,
                                   const struct iio_chan_spec *chan,
                                   enum iio_event_type type,
                                   enum iio_event_direction dir,
                                   enum iio_event_info info,
                                   int *val, int *val2)
{
        struct ad7291_chip_info *chip = iio_priv(indio_dev);
        int ret;
        u16 uval;

        ret = ad7291_i2c_read(chip, ad7291_threshold_reg(chan, dir, info),
                              &uval);
        if (ret < 0)
                return ret;

        if (info == IIO_EV_INFO_HYSTERESIS || chan->type == IIO_VOLTAGE)
                *val = uval & AD7291_VALUE_MASK;

        else
                *val = sign_extend32(uval, 11);

        return IIO_VAL_INT;
}

static int ad7291_write_event_value(struct iio_dev *indio_dev,
                                    const struct iio_chan_spec *chan,
                                    enum iio_event_type type,
                                    enum iio_event_direction dir,
                                    enum iio_event_info info,
                                    int val, int val2)
{
        struct ad7291_chip_info *chip = iio_priv(indio_dev);

        if (info == IIO_EV_INFO_HYSTERESIS || chan->type == IIO_VOLTAGE) {
                if (val > AD7291_VALUE_MASK || val < 0)
                        return -EINVAL;
        } else {
                if (val > 2047 || val < -2048)
                        return -EINVAL;
        }

        return ad7291_i2c_write(chip, ad7291_threshold_reg(chan, dir, info),
                                val);
}

static int ad7291_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 ad7291_chip_info *chip = iio_priv(indio_dev);
        /*
         * To be enabled the channel must simply be on. If any are enabled
         * we are in continuous sampling mode
         */

        switch (chan->type) {
        case IIO_VOLTAGE:
                return !!(chip->c_mask & BIT(15 - chan->channel));
        case IIO_TEMP:
                /* always on */
                return 1;
        default:
                return -EINVAL;
        }

}

static int ad7291_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)
{
        int ret = 0;
        struct ad7291_chip_info *chip = iio_priv(indio_dev);
        unsigned int mask;
        u16 regval;

        mutex_lock(&chip->state_lock);
        regval = chip->command;
        /*
         * To be enabled the channel must simply be on. If any are enabled
         * use continuous sampling mode.
         * Possible to disable temp as well but that makes single read tricky.
         */

        mask = BIT(15 - chan->channel);

        switch (chan->type) {
        case IIO_VOLTAGE:
                if ((!state) && (chip->c_mask & mask))
                        chip->c_mask &= ~mask;
                else if (state && (!(chip->c_mask & mask)))
                        chip->c_mask |= mask;
                else
                        break;

                regval &= ~AD7291_AUTOCYCLE;
                regval |= chip->c_mask;
                if (chip->c_mask) /* Enable autocycle? */
                        regval |= AD7291_AUTOCYCLE;

                ret = ad7291_i2c_write(chip, AD7291_COMMAND, regval);
                if (ret < 0)
                        goto error_ret;

                chip->command = regval;
                break;
        default:
                ret = -EINVAL;
        }

error_ret:
        mutex_unlock(&chip->state_lock);
        return ret;
}

static int ad7291_read_raw(struct iio_dev *indio_dev,
                           struct iio_chan_spec const *chan,
                           int *val,
                           int *val2,
                           long mask)
{
        int ret;
        struct ad7291_chip_info *chip = iio_priv(indio_dev);
        u16 regval;

        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                switch (chan->type) {
                case IIO_VOLTAGE:
                        mutex_lock(&chip->state_lock);
                        /* If in autocycle mode drop through */
                        if (chip->command & AD7291_AUTOCYCLE) {
                                mutex_unlock(&chip->state_lock);
                                return -EBUSY;
                        }
                        /* Enable this channel alone */
                        regval = chip->command & (~AD7291_VOLTAGE_MASK);
                        regval |= BIT(15 - chan->channel);
                        ret = ad7291_i2c_write(chip, AD7291_COMMAND, regval);
                        if (ret < 0) {
                                mutex_unlock(&chip->state_lock);
                                return ret;
                        }
                        /* Read voltage */
                        ret = i2c_smbus_read_word_swapped(chip->client,
                                                          AD7291_VOLTAGE);
                        if (ret < 0) {
                                mutex_unlock(&chip->state_lock);
                                return ret;
                        }
                        *val = ret & AD7291_VALUE_MASK;
                        mutex_unlock(&chip->state_lock);
                        return IIO_VAL_INT;
                case IIO_TEMP:
                        /* Assumes tsense bit of command register always set */
                        ret = i2c_smbus_read_word_swapped(chip->client,
                                                          AD7291_T_SENSE);
                        if (ret < 0)
                                return ret;
                        *val = sign_extend32(ret, 11);
                        return IIO_VAL_INT;
                default:
                        return -EINVAL;
                }
        case IIO_CHAN_INFO_AVERAGE_RAW:
                ret = i2c_smbus_read_word_swapped(chip->client,
                                                  AD7291_T_AVERAGE);
                        if (ret < 0)
                                return ret;
                        *val = sign_extend32(ret, 11);
                        return IIO_VAL_INT;
        case IIO_CHAN_INFO_SCALE:
                switch (chan->type) {
                case IIO_VOLTAGE:
                        if (chip->reg) {
                                int vref;

                                vref = regulator_get_voltage(chip->reg);
                                if (vref < 0)
                                        return vref;
                                *val = vref / 1000;
                        } else {
                                *val = 2500;
                        }
                        *val2 = AD7291_BITS;
                        return IIO_VAL_FRACTIONAL_LOG2;
                case IIO_TEMP:
                        /*
                         * One LSB of the ADC corresponds to 0.25 deg C.
                         * The temperature reading is in 12-bit twos
                         * complement format
                         */
                        *val = 250;
                        return IIO_VAL_INT;
                default:
                        return -EINVAL;
                }
        default:
                return -EINVAL;
        }
}

static const struct iio_event_spec ad7291_events[] = {
        {
                .type = IIO_EV_TYPE_THRESH,
                .dir = IIO_EV_DIR_RISING,
                .mask_separate = BIT(IIO_EV_INFO_VALUE) |
                        BIT(IIO_EV_INFO_ENABLE),
        }, {
                .type = IIO_EV_TYPE_THRESH,
                .dir = IIO_EV_DIR_FALLING,
                .mask_separate = BIT(IIO_EV_INFO_VALUE) |
                        BIT(IIO_EV_INFO_ENABLE),
        }, {
                .type = IIO_EV_TYPE_THRESH,
                .dir = IIO_EV_DIR_EITHER,
                .mask_separate = BIT(IIO_EV_INFO_HYSTERESIS),
        },
};

#define AD7291_VOLTAGE_CHAN(_chan)                                      \
{                                                                       \
        .type = IIO_VOLTAGE,                                            \
        .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),                   \
        .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),           \
        .indexed = 1,                                                   \
        .channel = _chan,                                               \
        .event_spec = ad7291_events,                                    \
        .num_event_specs = ARRAY_SIZE(ad7291_events),                   \
}

static const struct iio_chan_spec ad7291_channels[] = {
        AD7291_VOLTAGE_CHAN(0),
        AD7291_VOLTAGE_CHAN(1),
        AD7291_VOLTAGE_CHAN(2),
        AD7291_VOLTAGE_CHAN(3),
        AD7291_VOLTAGE_CHAN(4),
        AD7291_VOLTAGE_CHAN(5),
        AD7291_VOLTAGE_CHAN(6),
        AD7291_VOLTAGE_CHAN(7),
        {
                .type = IIO_TEMP,
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
                                BIT(IIO_CHAN_INFO_AVERAGE_RAW) |
                                BIT(IIO_CHAN_INFO_SCALE),
                .indexed = 1,
                .channel = 0,
                .event_spec = ad7291_events,
                .num_event_specs = ARRAY_SIZE(ad7291_events),
        }
};

static const struct iio_info ad7291_info = {
        .read_raw = &ad7291_read_raw,
        .read_event_config = &ad7291_read_event_config,
        .write_event_config = &ad7291_write_event_config,
        .read_event_value = &ad7291_read_event_value,
        .write_event_value = &ad7291_write_event_value,
};

static void ad7291_reg_disable(void *reg)
{
        regulator_disable(reg);
}

static int ad7291_probe(struct i2c_client *client)
{
        const struct i2c_device_id *id = i2c_client_get_device_id(client);
        struct ad7291_chip_info *chip;
        struct iio_dev *indio_dev;
        int ret;

        indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*chip));
        if (!indio_dev)
                return -ENOMEM;
        chip = iio_priv(indio_dev);

        mutex_init(&chip->state_lock);

        chip->client = client;

        chip->command = AD7291_NOISE_DELAY |
                        AD7291_T_SENSE_MASK | /* Tsense always enabled */
                        AD7291_ALERT_POLARITY; /* set irq polarity low level */

        chip->reg = devm_regulator_get_optional(&client->dev, "vref");
        if (IS_ERR(chip->reg)) {
                if (PTR_ERR(chip->reg) != -ENODEV)
                        return PTR_ERR(chip->reg);

                chip->reg = NULL;
        }

        if (chip->reg) {
                ret = regulator_enable(chip->reg);
                if (ret)
                        return ret;

                ret = devm_add_action_or_reset(&client->dev, ad7291_reg_disable,
                                               chip->reg);
                if (ret)
                        return ret;

                chip->command |= AD7291_EXT_REF;
        }

        indio_dev->name = id->name;
        indio_dev->channels = ad7291_channels;
        indio_dev->num_channels = ARRAY_SIZE(ad7291_channels);

        indio_dev->info = &ad7291_info;
        indio_dev->modes = INDIO_DIRECT_MODE;

        ret = ad7291_i2c_write(chip, AD7291_COMMAND, AD7291_RESET);
        if (ret)
                return -EIO;

        ret = ad7291_i2c_write(chip, AD7291_COMMAND, chip->command);
        if (ret)
                return -EIO;

        if (client->irq > 0) {
                ret = devm_request_threaded_irq(&client->dev, client->irq,
                                                NULL,
                                                &ad7291_event_handler,
                                                IRQF_TRIGGER_LOW | IRQF_ONESHOT,
                                                id->name,
                                                indio_dev);
                if (ret)
                        return ret;
        }

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

static const struct i2c_device_id ad7291_id[] = {
        { "ad7291" },
        { }
};

MODULE_DEVICE_TABLE(i2c, ad7291_id);

static const struct of_device_id ad7291_of_match[] = {
        { .compatible = "adi,ad7291" },
        { }
};
MODULE_DEVICE_TABLE(of, ad7291_of_match);

static struct i2c_driver ad7291_driver = {
        .driver = {
                .name = KBUILD_MODNAME,
                .of_match_table = ad7291_of_match,
        },
        .probe = ad7291_probe,
        .id_table = ad7291_id,
};
module_i2c_driver(ad7291_driver);

MODULE_AUTHOR("Sonic Zhang <sonic.zhang@analog.com>");
MODULE_DESCRIPTION("Analog Devices AD7291 ADC driver");
MODULE_LICENSE("GPL v2");