// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * max30102.c - Support for MAX30102 heart rate and pulse oximeter sensor
 *
 * Copyright (C) 2017 Matt Ranostay <matt.ranostay@konsulko.com>
 *
 * Support for MAX30105 optical particle sensor
 * Copyright (C) 2017 Peter Meerwald-Stadler <pmeerw@pmeerw.net>
 *
 * 7-bit I2C chip address: 0x57
 * TODO: proximity power saving feature
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/irq.h>
#include <linux/i2c.h>
#include <linux/mutex.h>
#include <linux/mod_devicetable.h>
#include <linux/regmap.h>
#include <linux/iio/iio.h>
#include <linux/iio/buffer.h>
#include <linux/iio/kfifo_buf.h>

#define MAX30102_DRV_NAME       "max30102"
#define MAX30102_PART_NUMBER    0x15

enum max30102_chip_id {
        max30102,
        max30105,
};

enum max3012_led_idx {
        MAX30102_LED_RED,
        MAX30102_LED_IR,
        MAX30105_LED_GREEN,
};

#define MAX30102_REG_INT_STATUS                 0x00
#define MAX30102_REG_INT_STATUS_PWR_RDY         BIT(0)
#define MAX30102_REG_INT_STATUS_PROX_INT        BIT(4)
#define MAX30102_REG_INT_STATUS_ALC_OVF         BIT(5)
#define MAX30102_REG_INT_STATUS_PPG_RDY         BIT(6)
#define MAX30102_REG_INT_STATUS_FIFO_RDY        BIT(7)

#define MAX30102_REG_INT_ENABLE                 0x02
#define MAX30102_REG_INT_ENABLE_PROX_INT_EN     BIT(4)
#define MAX30102_REG_INT_ENABLE_ALC_OVF_EN      BIT(5)
#define MAX30102_REG_INT_ENABLE_PPG_EN          BIT(6)
#define MAX30102_REG_INT_ENABLE_FIFO_EN         BIT(7)
#define MAX30102_REG_INT_ENABLE_MASK            0xf0
#define MAX30102_REG_INT_ENABLE_MASK_SHIFT      4

#define MAX30102_REG_FIFO_WR_PTR                0x04
#define MAX30102_REG_FIFO_OVR_CTR               0x05
#define MAX30102_REG_FIFO_RD_PTR                0x06
#define MAX30102_REG_FIFO_DATA                  0x07
#define MAX30102_REG_FIFO_DATA_BYTES            3

#define MAX30102_REG_FIFO_CONFIG                0x08
#define MAX30102_REG_FIFO_CONFIG_AVG_4SAMPLES   BIT(1)
#define MAX30102_REG_FIFO_CONFIG_AVG_SHIFT      5
#define MAX30102_REG_FIFO_CONFIG_AFULL          BIT(0)

#define MAX30102_REG_MODE_CONFIG                0x09
#define MAX30102_REG_MODE_CONFIG_MODE_NONE      0x00
#define MAX30102_REG_MODE_CONFIG_MODE_HR        0x02 /* red LED */
#define MAX30102_REG_MODE_CONFIG_MODE_HR_SPO2   0x03 /* red + IR LED */
#define MAX30102_REG_MODE_CONFIG_MODE_MULTI     0x07 /* multi-LED mode */
#define MAX30102_REG_MODE_CONFIG_MODE_MASK      GENMASK(2, 0)
#define MAX30102_REG_MODE_CONFIG_PWR            BIT(7)

#define MAX30102_REG_MODE_CONTROL_SLOT21        0x11 /* multi-LED control */
#define MAX30102_REG_MODE_CONTROL_SLOT43        0x12
#define MAX30102_REG_MODE_CONTROL_SLOT_MASK     (GENMASK(6, 4) | GENMASK(2, 0))
#define MAX30102_REG_MODE_CONTROL_SLOT_SHIFT    4

#define MAX30102_REG_SPO2_CONFIG                0x0a
#define MAX30102_REG_SPO2_CONFIG_PULSE_411_US   0x03
#define MAX30102_REG_SPO2_CONFIG_SR_400HZ       0x03
#define MAX30102_REG_SPO2_CONFIG_SR_MASK        0x07
#define MAX30102_REG_SPO2_CONFIG_SR_MASK_SHIFT  2
#define MAX30102_REG_SPO2_CONFIG_ADC_4096_STEPS BIT(0)
#define MAX30102_REG_SPO2_CONFIG_ADC_MASK_SHIFT 5

#define MAX30102_REG_RED_LED_CONFIG             0x0c
#define MAX30102_REG_IR_LED_CONFIG              0x0d
#define MAX30105_REG_GREEN_LED_CONFIG           0x0e

#define MAX30102_REG_TEMP_CONFIG                0x21
#define MAX30102_REG_TEMP_CONFIG_TEMP_EN        BIT(0)

#define MAX30102_REG_TEMP_INTEGER               0x1f
#define MAX30102_REG_TEMP_FRACTION              0x20

#define MAX30102_REG_REV_ID                     0xfe
#define MAX30102_REG_PART_ID                    0xff

struct max30102_data {
        struct i2c_client *client;
        struct iio_dev *indio_dev;
        struct mutex lock;
        struct regmap *regmap;
        enum max30102_chip_id chip_id;

        u8 buffer[12];
        __be32 processed_buffer[3]; /* 3 x 18-bit (padded to 32-bits) */
};

static const struct regmap_config max30102_regmap_config = {
        .name = "max30102_regmap",

        .reg_bits = 8,
        .val_bits = 8,
};

static const unsigned long max30102_scan_masks[] = {
        BIT(MAX30102_LED_RED) | BIT(MAX30102_LED_IR),
        0
};

static const unsigned long max30105_scan_masks[] = {
        BIT(MAX30102_LED_RED) | BIT(MAX30102_LED_IR),
        BIT(MAX30102_LED_RED) | BIT(MAX30102_LED_IR) |
                BIT(MAX30105_LED_GREEN),
        0
};

#define MAX30102_INTENSITY_CHANNEL(_si, _mod) { \
                .type = IIO_INTENSITY, \
                .channel2 = _mod, \
                .modified = 1, \
                .scan_index = _si, \
                .scan_type = { \
                        .sign = 'u', \
                        .shift = 8, \
                        .realbits = 18, \
                        .storagebits = 32, \
                        .endianness = IIO_BE, \
                }, \
        }

static const struct iio_chan_spec max30102_channels[] = {
        MAX30102_INTENSITY_CHANNEL(MAX30102_LED_RED, IIO_MOD_LIGHT_RED),
        MAX30102_INTENSITY_CHANNEL(MAX30102_LED_IR, IIO_MOD_LIGHT_IR),
        {
                .type = IIO_TEMP,
                .info_mask_separate =
                        BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
                .scan_index = -1,
        },
};

static const struct iio_chan_spec max30105_channels[] = {
        MAX30102_INTENSITY_CHANNEL(MAX30102_LED_RED, IIO_MOD_LIGHT_RED),
        MAX30102_INTENSITY_CHANNEL(MAX30102_LED_IR, IIO_MOD_LIGHT_IR),
        MAX30102_INTENSITY_CHANNEL(MAX30105_LED_GREEN, IIO_MOD_LIGHT_GREEN),
        {
                .type = IIO_TEMP,
                .info_mask_separate =
                        BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
                .scan_index = -1,
        },
};

static int max30102_set_power(struct max30102_data *data, bool en)
{
        return regmap_update_bits(data->regmap, MAX30102_REG_MODE_CONFIG,
                                  MAX30102_REG_MODE_CONFIG_PWR,
                                  en ? 0 : MAX30102_REG_MODE_CONFIG_PWR);
}

static int max30102_set_powermode(struct max30102_data *data, u8 mode, bool en)
{
        u8 reg = mode;

        if (!en)
                reg |= MAX30102_REG_MODE_CONFIG_PWR;

        return regmap_update_bits(data->regmap, MAX30102_REG_MODE_CONFIG,
                                  MAX30102_REG_MODE_CONFIG_PWR |
                                  MAX30102_REG_MODE_CONFIG_MODE_MASK, reg);
}

#define MAX30102_MODE_CONTROL_LED_SLOTS(slot2, slot1) \
        ((slot2 << MAX30102_REG_MODE_CONTROL_SLOT_SHIFT) | slot1)

static int max30102_buffer_postenable(struct iio_dev *indio_dev)
{
        struct max30102_data *data = iio_priv(indio_dev);
        int ret;
        u8 reg;

        switch (*indio_dev->active_scan_mask) {
        case BIT(MAX30102_LED_RED) | BIT(MAX30102_LED_IR):
                reg = MAX30102_REG_MODE_CONFIG_MODE_HR_SPO2;
                break;
        case BIT(MAX30102_LED_RED) | BIT(MAX30102_LED_IR) |
             BIT(MAX30105_LED_GREEN):
                ret = regmap_update_bits(data->regmap,
                                         MAX30102_REG_MODE_CONTROL_SLOT21,
                                         MAX30102_REG_MODE_CONTROL_SLOT_MASK,
                                         MAX30102_MODE_CONTROL_LED_SLOTS(2, 1));
                if (ret)
                        return ret;

                ret = regmap_update_bits(data->regmap,
                                         MAX30102_REG_MODE_CONTROL_SLOT43,
                                         MAX30102_REG_MODE_CONTROL_SLOT_MASK,
                                         MAX30102_MODE_CONTROL_LED_SLOTS(0, 3));
                if (ret)
                        return ret;

                reg = MAX30102_REG_MODE_CONFIG_MODE_MULTI;
                break;
        default:
                return -EINVAL;
        }

        return max30102_set_powermode(data, reg, true);
}

static int max30102_buffer_predisable(struct iio_dev *indio_dev)
{
        struct max30102_data *data = iio_priv(indio_dev);

        return max30102_set_powermode(data, MAX30102_REG_MODE_CONFIG_MODE_NONE,
                                      false);
}

static const struct iio_buffer_setup_ops max30102_buffer_setup_ops = {
        .postenable = max30102_buffer_postenable,
        .predisable = max30102_buffer_predisable,
};

static inline int max30102_fifo_count(struct max30102_data *data)
{
        unsigned int val;
        int ret;

        ret = regmap_read(data->regmap, MAX30102_REG_INT_STATUS, &val);
        if (ret)
                return ret;

        /* FIFO has one sample slot left */
        if (val & MAX30102_REG_INT_STATUS_FIFO_RDY)
                return 1;

        return 0;
}

#define MAX30102_COPY_DATA(i) \
        memcpy(&data->processed_buffer[(i)], \
               &buffer[(i) * MAX30102_REG_FIFO_DATA_BYTES], \
               MAX30102_REG_FIFO_DATA_BYTES)

static int max30102_read_measurement(struct max30102_data *data,
                                     unsigned int measurements)
{
        int ret;
        u8 *buffer = (u8 *) &data->buffer;

        ret = i2c_smbus_read_i2c_block_data(data->client,
                                            MAX30102_REG_FIFO_DATA,
                                            measurements *
                                            MAX30102_REG_FIFO_DATA_BYTES,
                                            buffer);

        switch (measurements) {
        case 3:
                MAX30102_COPY_DATA(2);
                fallthrough;
        case 2:
                MAX30102_COPY_DATA(1);
                fallthrough;
        case 1:
                MAX30102_COPY_DATA(0);
                break;
        default:
                return -EINVAL;
        }

        return (ret == measurements * MAX30102_REG_FIFO_DATA_BYTES) ?
               0 : -EINVAL;
}

static irqreturn_t max30102_interrupt_handler(int irq, void *private)
{
        struct iio_dev *indio_dev = private;
        struct max30102_data *data = iio_priv(indio_dev);
        unsigned int measurements = bitmap_weight(indio_dev->active_scan_mask,
                                                  iio_get_masklength(indio_dev));
        int ret, cnt = 0;

        mutex_lock(&data->lock);

        while (cnt || (cnt = max30102_fifo_count(data)) > 0) {
                ret = max30102_read_measurement(data, measurements);
                if (ret)
                        break;

                iio_push_to_buffers(data->indio_dev, data->processed_buffer);
                cnt--;
        }

        mutex_unlock(&data->lock);

        return IRQ_HANDLED;
}

static int max30102_get_current_idx(unsigned int val, int *reg)
{
        /* each step is 0.200 mA */
        *reg = val / 200;

        return *reg > 0xff ? -EINVAL : 0;
}

static int max30102_led_init(struct max30102_data *data)
{
        struct device *dev = &data->client->dev;
        unsigned int val;
        int reg, ret;

        ret = device_property_read_u32(dev, "maxim,red-led-current-microamp", &val);
        if (ret) {
                dev_info(dev, "no red-led-current-microamp set\n");

                /* Default to 7 mA RED LED */
                val = 7000;
        }

        ret = max30102_get_current_idx(val, &reg);
        if (ret) {
                dev_err(dev, "invalid RED LED current setting %d\n", val);
                return ret;
        }

        ret = regmap_write(data->regmap, MAX30102_REG_RED_LED_CONFIG, reg);
        if (ret)
                return ret;

        if (data->chip_id == max30105) {
                ret = device_property_read_u32(dev,
                        "maxim,green-led-current-microamp", &val);
                if (ret) {
                        dev_info(dev, "no green-led-current-microamp set\n");

                        /* Default to 7 mA green LED */
                        val = 7000;
                }

                ret = max30102_get_current_idx(val, &reg);
                if (ret) {
                        dev_err(dev, "invalid green LED current setting %d\n",
                                val);
                        return ret;
                }

                ret = regmap_write(data->regmap, MAX30105_REG_GREEN_LED_CONFIG,
                                   reg);
                if (ret)
                        return ret;
        }

        ret = device_property_read_u32(dev, "maxim,ir-led-current-microamp", &val);
        if (ret) {
                dev_info(dev, "no ir-led-current-microamp set\n");

                /* Default to 7 mA IR LED */
                val = 7000;
        }

        ret = max30102_get_current_idx(val, &reg);
        if (ret) {
                dev_err(dev, "invalid IR LED current setting %d\n", val);
                return ret;
        }

        return regmap_write(data->regmap, MAX30102_REG_IR_LED_CONFIG, reg);
}

static int max30102_chip_init(struct max30102_data *data)
{
        int ret;

        /* setup LED current settings */
        ret = max30102_led_init(data);
        if (ret)
                return ret;

        /* configure 18-bit HR + SpO2 readings at 400Hz */
        ret = regmap_write(data->regmap, MAX30102_REG_SPO2_CONFIG,
                                (MAX30102_REG_SPO2_CONFIG_ADC_4096_STEPS
                                 << MAX30102_REG_SPO2_CONFIG_ADC_MASK_SHIFT) |
                                (MAX30102_REG_SPO2_CONFIG_SR_400HZ
                                 << MAX30102_REG_SPO2_CONFIG_SR_MASK_SHIFT) |
                                 MAX30102_REG_SPO2_CONFIG_PULSE_411_US);
        if (ret)
                return ret;

        /* average 4 samples + generate FIFO interrupt */
        ret = regmap_write(data->regmap, MAX30102_REG_FIFO_CONFIG,
                                (MAX30102_REG_FIFO_CONFIG_AVG_4SAMPLES
                                 << MAX30102_REG_FIFO_CONFIG_AVG_SHIFT) |
                                 MAX30102_REG_FIFO_CONFIG_AFULL);
        if (ret)
                return ret;

        /* enable FIFO interrupt */
        return regmap_update_bits(data->regmap, MAX30102_REG_INT_ENABLE,
                                 MAX30102_REG_INT_ENABLE_MASK,
                                 MAX30102_REG_INT_ENABLE_FIFO_EN);
}

static int max30102_read_temp(struct max30102_data *data, int *val)
{
        int ret;
        unsigned int reg;

        ret = regmap_read(data->regmap, MAX30102_REG_TEMP_INTEGER, &reg);
        if (ret < 0)
                return ret;
        *val = reg << 4;

        ret = regmap_read(data->regmap, MAX30102_REG_TEMP_FRACTION, &reg);
        if (ret < 0)
                return ret;

        *val |= reg & 0xf;
        *val = sign_extend32(*val, 11);

        return 0;
}

static int max30102_get_temp(struct max30102_data *data, int *val, bool en)
{
        int ret;

        if (en) {
                ret = max30102_set_power(data, true);
                if (ret)
                        return ret;
        }

        /* start acquisition */
        ret = regmap_set_bits(data->regmap, MAX30102_REG_TEMP_CONFIG,
                              MAX30102_REG_TEMP_CONFIG_TEMP_EN);
        if (ret)
                goto out;

        msleep(35);
        ret = max30102_read_temp(data, val);

out:
        if (en)
                max30102_set_power(data, false);

        return ret;
}

static int max30102_read_raw(struct iio_dev *indio_dev,
                             struct iio_chan_spec const *chan,
                             int *val, int *val2, long mask)
{
        struct max30102_data *data = iio_priv(indio_dev);
        int ret;

        switch (mask) {
        case IIO_CHAN_INFO_RAW: {
                /*
                 * Temperature reading can only be acquired when not in
                 * shutdown; leave shutdown briefly when buffer not running
                 */
                IIO_DEV_GUARD_CURRENT_MODE(indio_dev);

                ret = max30102_get_temp(data, val, !iio_buffer_enabled(indio_dev));
                if (ret)
                        return ret;

                return IIO_VAL_INT;
        }
        case IIO_CHAN_INFO_SCALE:
                *val = 1000;  /* 62.5 */
                *val2 = 16;
                return IIO_VAL_FRACTIONAL;
        default:
                return -EINVAL;
        }
}

static const struct iio_info max30102_info = {
        .read_raw = max30102_read_raw,
};

static int max30102_probe(struct i2c_client *client)
{
        const struct i2c_device_id *id = i2c_client_get_device_id(client);
        struct max30102_data *data;
        struct iio_dev *indio_dev;
        int ret;
        unsigned int reg;

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

        indio_dev->name = MAX30102_DRV_NAME;
        indio_dev->info = &max30102_info;
        indio_dev->modes = INDIO_DIRECT_MODE;

        data = iio_priv(indio_dev);
        data->indio_dev = indio_dev;
        data->client = client;
        data->chip_id = id->driver_data;

        mutex_init(&data->lock);
        i2c_set_clientdata(client, indio_dev);

        switch (data->chip_id) {
        case max30105:
                indio_dev->channels = max30105_channels;
                indio_dev->num_channels = ARRAY_SIZE(max30105_channels);
                indio_dev->available_scan_masks = max30105_scan_masks;
                break;
        case max30102:
                indio_dev->channels = max30102_channels;
                indio_dev->num_channels = ARRAY_SIZE(max30102_channels);
                indio_dev->available_scan_masks = max30102_scan_masks;
                break;
        default:
                return -ENODEV;
        }

        ret = devm_iio_kfifo_buffer_setup(&client->dev, indio_dev,
                                          &max30102_buffer_setup_ops);
        if (ret)
                return ret;

        data->regmap = devm_regmap_init_i2c(client, &max30102_regmap_config);
        if (IS_ERR(data->regmap)) {
                dev_err(&client->dev, "regmap initialization failed\n");
                return PTR_ERR(data->regmap);
        }

        /* check part ID */
        ret = regmap_read(data->regmap, MAX30102_REG_PART_ID, &reg);
        if (ret)
                return ret;
        if (reg != MAX30102_PART_NUMBER)
                return -ENODEV;

        /* show revision ID */
        ret = regmap_read(data->regmap, MAX30102_REG_REV_ID, &reg);
        if (ret)
                return ret;
        dev_dbg(&client->dev, "max3010x revision %02x\n", reg);

        /* clear mode setting, chip shutdown */
        ret = max30102_set_powermode(data, MAX30102_REG_MODE_CONFIG_MODE_NONE,
                                     false);
        if (ret)
                return ret;

        ret = max30102_chip_init(data);
        if (ret)
                return ret;

        if (client->irq <= 0) {
                dev_err(&client->dev, "no valid irq defined\n");
                return -EINVAL;
        }

        ret = devm_request_threaded_irq(&client->dev, client->irq,
                                        NULL, max30102_interrupt_handler,
                                        IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
                                        "max30102_irq", indio_dev);
        if (ret) {
                dev_err(&client->dev, "request irq (%d) failed\n", client->irq);
                return ret;
        }

        return iio_device_register(indio_dev);
}

static void max30102_remove(struct i2c_client *client)
{
        struct iio_dev *indio_dev = i2c_get_clientdata(client);
        struct max30102_data *data = iio_priv(indio_dev);

        iio_device_unregister(indio_dev);
        max30102_set_power(data, false);
}

static const struct i2c_device_id max30102_id[] = {
        { "max30101", max30105 },
        { "max30102", max30102 },
        { "max30105", max30105 },
        { }
};
MODULE_DEVICE_TABLE(i2c, max30102_id);

static const struct of_device_id max30102_dt_ids[] = {
        { .compatible = "maxim,max30101" },
        { .compatible = "maxim,max30102" },
        { .compatible = "maxim,max30105" },
        { }
};
MODULE_DEVICE_TABLE(of, max30102_dt_ids);

static struct i2c_driver max30102_driver = {
        .driver = {
                .name   = MAX30102_DRV_NAME,
                .of_match_table = max30102_dt_ids,
        },
        .probe          = max30102_probe,
        .remove         = max30102_remove,
        .id_table       = max30102_id,
};
module_i2c_driver(max30102_driver);

MODULE_AUTHOR("Matt Ranostay <matt.ranostay@konsulko.com>");
MODULE_DESCRIPTION("MAX30102 heart rate/pulse oximeter and MAX30105 particle sensor driver");
MODULE_LICENSE("GPL");