// SPDX-License-Identifier: GPL-2.0+
/*
 * max30100.c - Support for MAX30100 heart rate and pulse oximeter sensor
 *
 * Copyright (C) 2015, 2018
 * Author: Matt Ranostay <matt.ranostay@konsulko.com>
 *
 */

#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/property.h>
#include <linux/regmap.h>
#include <linux/bitfield.h>
#include <linux/iio/iio.h>
#include <linux/iio/buffer.h>
#include <linux/iio/kfifo_buf.h>

#define MAX30100_DRV_NAME       "max30100"

#define MAX30100_REG_INT_STATUS                 0x00
#define MAX30100_REG_INT_STATUS_PWR_RDY         BIT(0)
#define MAX30100_REG_INT_STATUS_SPO2_RDY        BIT(4)
#define MAX30100_REG_INT_STATUS_HR_RDY          BIT(5)
#define MAX30100_REG_INT_STATUS_FIFO_RDY        BIT(7)

#define MAX30100_REG_INT_ENABLE                 0x01
#define MAX30100_REG_INT_ENABLE_SPO2_EN         BIT(0)
#define MAX30100_REG_INT_ENABLE_HR_EN           BIT(1)
#define MAX30100_REG_INT_ENABLE_FIFO_EN         BIT(3)
#define MAX30100_REG_INT_ENABLE_MASK            0xf0
#define MAX30100_REG_INT_ENABLE_MASK_SHIFT      4

#define MAX30100_REG_FIFO_WR_PTR                0x02
#define MAX30100_REG_FIFO_OVR_CTR               0x03
#define MAX30100_REG_FIFO_RD_PTR                0x04
#define MAX30100_REG_FIFO_DATA                  0x05
#define MAX30100_REG_FIFO_DATA_ENTRY_COUNT      16
#define MAX30100_REG_FIFO_DATA_ENTRY_LEN        4

#define MAX30100_REG_MODE_CONFIG                0x06
#define MAX30100_REG_MODE_CONFIG_MODE_SPO2_EN   BIT(0)
#define MAX30100_REG_MODE_CONFIG_MODE_HR_EN     BIT(1)
#define MAX30100_REG_MODE_CONFIG_MODE_MASK      0x03
#define MAX30100_REG_MODE_CONFIG_TEMP_EN        BIT(3)
#define MAX30100_REG_MODE_CONFIG_PWR            BIT(7)

#define MAX30100_REG_SPO2_CONFIG                0x07
#define MAX30100_REG_SPO2_CONFIG_PW_MASK        GENMASK(1, 0)
#define MAX30100_REG_SPO2_CONFIG_200US          0x0
#define MAX30100_REG_SPO2_CONFIG_400US          0x1
#define MAX30100_REG_SPO2_CONFIG_800US          0x2
#define MAX30100_REG_SPO2_CONFIG_1600US         0x3
#define MAX30100_REG_SPO2_CONFIG_100HZ          BIT(2)
#define MAX30100_REG_SPO2_CONFIG_HI_RES_EN      BIT(6)

#define MAX30100_REG_LED_CONFIG                 0x09
#define MAX30100_REG_LED_CONFIG_LED_MASK        0x0f
#define MAX30100_REG_LED_CONFIG_RED_LED_SHIFT   4

#define MAX30100_REG_LED_CONFIG_24MA            0x07
#define MAX30100_REG_LED_CONFIG_50MA            0x0f

#define MAX30100_REG_TEMP_INTEGER               0x16
#define MAX30100_REG_TEMP_FRACTION              0x17

struct max30100_data {
        struct i2c_client *client;
        struct iio_dev *indio_dev;
        struct mutex lock;
        struct regmap *regmap;

        __be16 buffer[2]; /* 2 16-bit channels */
};

static bool max30100_is_volatile_reg(struct device *dev, unsigned int reg)
{
        switch (reg) {
        case MAX30100_REG_INT_STATUS:
        case MAX30100_REG_MODE_CONFIG:
        case MAX30100_REG_FIFO_WR_PTR:
        case MAX30100_REG_FIFO_OVR_CTR:
        case MAX30100_REG_FIFO_RD_PTR:
        case MAX30100_REG_FIFO_DATA:
        case MAX30100_REG_TEMP_INTEGER:
        case MAX30100_REG_TEMP_FRACTION:
                return true;
        default:
                return false;
        }
}

static const struct regmap_config max30100_regmap_config = {
        .name = "max30100_regmap",

        .reg_bits = 8,
        .val_bits = 8,

        .max_register = MAX30100_REG_TEMP_FRACTION,
        .cache_type = REGCACHE_FLAT,

        .volatile_reg = max30100_is_volatile_reg,
};

static const unsigned int max30100_led_current_mapping[] = {
        4400, 7600, 11000, 14200, 17400,
        20800, 24000, 27100, 30600, 33800,
        37000, 40200, 43600, 46800, 50000
};

static const unsigned long max30100_scan_masks[] = {0x3, 0};

static const struct iio_chan_spec max30100_channels[] = {
        {
                .type = IIO_INTENSITY,
                .channel2 = IIO_MOD_LIGHT_IR,
                .modified = 1,

                .scan_index = 0,
                .scan_type = {
                        .sign = 'u',
                        .realbits = 16,
                        .storagebits = 16,
                        .endianness = IIO_BE,
                },
        },
        {
                .type = IIO_INTENSITY,
                .channel2 = IIO_MOD_LIGHT_RED,
                .modified = 1,

                .scan_index = 1,
                .scan_type = {
                        .sign = 'u',
                        .realbits = 16,
                        .storagebits = 16,
                        .endianness = IIO_BE,
                },
        },
        {
                .type = IIO_TEMP,
                .info_mask_separate =
                        BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
                .scan_index = -1,
        },
};

static int max30100_set_powermode(struct max30100_data *data, bool state)
{
        return regmap_update_bits(data->regmap, MAX30100_REG_MODE_CONFIG,
                                  MAX30100_REG_MODE_CONFIG_PWR,
                                  state ? 0 : MAX30100_REG_MODE_CONFIG_PWR);
}

static int max30100_clear_fifo(struct max30100_data *data)
{
        int ret;

        ret = regmap_write(data->regmap, MAX30100_REG_FIFO_WR_PTR, 0);
        if (ret)
                return ret;

        ret = regmap_write(data->regmap, MAX30100_REG_FIFO_OVR_CTR, 0);
        if (ret)
                return ret;

        return regmap_write(data->regmap, MAX30100_REG_FIFO_RD_PTR, 0);
}

static int max30100_buffer_postenable(struct iio_dev *indio_dev)
{
        struct max30100_data *data = iio_priv(indio_dev);
        int ret;

        ret = max30100_set_powermode(data, true);
        if (ret)
                return ret;

        return max30100_clear_fifo(data);
}

static int max30100_buffer_predisable(struct iio_dev *indio_dev)
{
        struct max30100_data *data = iio_priv(indio_dev);

        return max30100_set_powermode(data, false);
}

static const struct iio_buffer_setup_ops max30100_buffer_setup_ops = {
        .postenable = max30100_buffer_postenable,
        .predisable = max30100_buffer_predisable,
};

static inline int max30100_fifo_count(struct max30100_data *data)
{
        unsigned int val;
        int ret;

        ret = regmap_read(data->regmap, MAX30100_REG_INT_STATUS, &val);
        if (ret)
                return ret;

        /* FIFO is almost full */
        if (val & MAX30100_REG_INT_STATUS_FIFO_RDY)
                return MAX30100_REG_FIFO_DATA_ENTRY_COUNT - 1;

        return 0;
}

static int max30100_read_measurement(struct max30100_data *data)
{
        int ret;

        ret = i2c_smbus_read_i2c_block_data(data->client,
                                            MAX30100_REG_FIFO_DATA,
                                            MAX30100_REG_FIFO_DATA_ENTRY_LEN,
                                            (u8 *) &data->buffer);

        return (ret == MAX30100_REG_FIFO_DATA_ENTRY_LEN) ? 0 : ret;
}

static irqreturn_t max30100_interrupt_handler(int irq, void *private)
{
        struct iio_dev *indio_dev = private;
        struct max30100_data *data = iio_priv(indio_dev);
        int ret, cnt = 0;

        mutex_lock(&data->lock);

        while (cnt || (cnt = max30100_fifo_count(data)) > 0) {
                ret = max30100_read_measurement(data);
                if (ret)
                        break;

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

        mutex_unlock(&data->lock);

        return IRQ_HANDLED;
}

static int max30100_get_current_idx(unsigned int val, int *reg)
{
        int idx;

        /* LED turned off */
        if (val == 0) {
                *reg = 0;
                return 0;
        }

        for (idx = 0; idx < ARRAY_SIZE(max30100_led_current_mapping); idx++) {
                if (max30100_led_current_mapping[idx] == val) {
                        *reg = idx + 1;
                        return 0;
                }
        }

        return -EINVAL;
}

static int max30100_led_init(struct max30100_data *data)
{
        struct device *dev = &data->client->dev;
        unsigned int val[2];
        int reg, ret;

        ret = device_property_read_u32_array(dev, "maxim,led-current-microamp",
                                        (unsigned int *) &val, 2);
        if (ret) {
                /* Default to 24 mA RED LED, 50 mA IR LED */
                reg = (MAX30100_REG_LED_CONFIG_24MA <<
                        MAX30100_REG_LED_CONFIG_RED_LED_SHIFT) |
                        MAX30100_REG_LED_CONFIG_50MA;
                dev_warn(dev, "no led-current-microamp set");

                return regmap_write(data->regmap, MAX30100_REG_LED_CONFIG, reg);
        }

        /* RED LED current */
        ret = max30100_get_current_idx(val[0], &reg);
        if (ret) {
                dev_err(dev, "invalid RED current setting %d", val[0]);
                return ret;
        }

        ret = regmap_update_bits(data->regmap, MAX30100_REG_LED_CONFIG,
                MAX30100_REG_LED_CONFIG_LED_MASK <<
                MAX30100_REG_LED_CONFIG_RED_LED_SHIFT,
                reg << MAX30100_REG_LED_CONFIG_RED_LED_SHIFT);
        if (ret)
                return ret;

        /* IR LED current */
        ret = max30100_get_current_idx(val[1], &reg);
        if (ret) {
                dev_err(dev, "invalid IR current setting %d", val[1]);
                return ret;
        }

        return regmap_update_bits(data->regmap, MAX30100_REG_LED_CONFIG,
                MAX30100_REG_LED_CONFIG_LED_MASK, reg);
}

static int max30100_get_pulse_width(unsigned int pwidth_us)
{
        switch (pwidth_us) {
        case 200:
                return MAX30100_REG_SPO2_CONFIG_200US;
        case 400:
                return MAX30100_REG_SPO2_CONFIG_400US;
        case 800:
                return MAX30100_REG_SPO2_CONFIG_800US;
        case 1600:
                return MAX30100_REG_SPO2_CONFIG_1600US;
        default:
                return -EINVAL;
        }
}

static int max30100_chip_init(struct max30100_data *data)
{
        int ret;
        int pulse_width;
        /* set default LED pulse-width to 1600 us */
        unsigned int pulse_us = 1600;
        struct device *dev = &data->client->dev;

        /* setup LED current settings */
        ret = max30100_led_init(data);
        if (ret)
                return ret;

        /* Read LED pulse-width-us from DT */
        device_property_read_u32(dev, "maxim,pulse-width-us", &pulse_us);

        pulse_width = max30100_get_pulse_width(pulse_us);
        if (pulse_width < 0)
                return dev_err_probe(dev, pulse_width, "invalid LED pulse-width %uus\n", pulse_us);

        /* enable hi-res SPO2 readings at 100Hz */
        ret = regmap_write(data->regmap, MAX30100_REG_SPO2_CONFIG,
                                 MAX30100_REG_SPO2_CONFIG_HI_RES_EN |
                                 MAX30100_REG_SPO2_CONFIG_100HZ |
                                 FIELD_PREP(MAX30100_REG_SPO2_CONFIG_PW_MASK, pulse_width));
        if (ret)
                return ret;

        /* enable SPO2 mode */
        ret = regmap_update_bits(data->regmap, MAX30100_REG_MODE_CONFIG,
                                 MAX30100_REG_MODE_CONFIG_MODE_MASK,
                                 MAX30100_REG_MODE_CONFIG_MODE_HR_EN |
                                 MAX30100_REG_MODE_CONFIG_MODE_SPO2_EN);
        if (ret)
                return ret;

        /* enable FIFO interrupt */
        return regmap_update_bits(data->regmap, MAX30100_REG_INT_ENABLE,
                                 MAX30100_REG_INT_ENABLE_MASK,
                                 MAX30100_REG_INT_ENABLE_FIFO_EN
                                 << MAX30100_REG_INT_ENABLE_MASK_SHIFT);
}

static int max30100_read_temp(struct max30100_data *data, int *val)
{
        int ret;
        unsigned int reg;

        ret = regmap_read(data->regmap, MAX30100_REG_TEMP_INTEGER, &reg);
        if (ret < 0)
                return ret;
        *val = reg << 4;

        ret = regmap_read(data->regmap, MAX30100_REG_TEMP_FRACTION, &reg);
        if (ret < 0)
                return ret;

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

        return 0;
}

static int max30100_get_temp(struct max30100_data *data, int *val)
{
        int ret;

        /* start acquisition */
        ret = regmap_set_bits(data->regmap, MAX30100_REG_MODE_CONFIG,
                              MAX30100_REG_MODE_CONFIG_TEMP_EN);
        if (ret)
                return ret;

        msleep(35);

        return max30100_read_temp(data, val);
}

static int max30100_read_raw(struct iio_dev *indio_dev,
                             struct iio_chan_spec const *chan,
                             int *val, int *val2, long mask)
{
        struct max30100_data *data = iio_priv(indio_dev);
        int ret = -EINVAL;

        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                /*
                 * Temperature reading can only be acquired while engine
                 * is running
                 */
                if (!iio_device_try_claim_buffer_mode(indio_dev)) {
                        ret = -EAGAIN;
                } else {
                        ret = max30100_get_temp(data, val);
                        if (!ret)
                                ret = IIO_VAL_INT;

                        iio_device_release_buffer_mode(indio_dev);
                }
                break;
        case IIO_CHAN_INFO_SCALE:
                *val = 1;  /* 0.0625 */
                *val2 = 16;
                ret = IIO_VAL_FRACTIONAL;
                break;
        }

        return ret;
}

static const struct iio_info max30100_info = {
        .read_raw = max30100_read_raw,
};

static int max30100_probe(struct i2c_client *client)
{
        struct max30100_data *data;
        struct iio_dev *indio_dev;
        int ret;

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

        indio_dev->name = MAX30100_DRV_NAME;
        indio_dev->channels = max30100_channels;
        indio_dev->info = &max30100_info;
        indio_dev->num_channels = ARRAY_SIZE(max30100_channels);
        indio_dev->available_scan_masks = max30100_scan_masks;
        indio_dev->modes = INDIO_DIRECT_MODE;

        ret = devm_iio_kfifo_buffer_setup(&client->dev, indio_dev,
                                          &max30100_buffer_setup_ops);
        if (ret)
                return ret;

        data = iio_priv(indio_dev);
        data->indio_dev = indio_dev;
        data->client = client;

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

        data->regmap = devm_regmap_init_i2c(client, &max30100_regmap_config);
        if (IS_ERR(data->regmap)) {
                dev_err(&client->dev, "regmap initialization failed.\n");
                return PTR_ERR(data->regmap);
        }
        max30100_set_powermode(data, false);

        ret = max30100_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, max30100_interrupt_handler,
                                        IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
                                        "max30100_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 max30100_remove(struct i2c_client *client)
{
        struct iio_dev *indio_dev = i2c_get_clientdata(client);
        struct max30100_data *data = iio_priv(indio_dev);

        iio_device_unregister(indio_dev);
        max30100_set_powermode(data, false);
}

static const struct i2c_device_id max30100_id[] = {
        { "max30100" },
        { }
};
MODULE_DEVICE_TABLE(i2c, max30100_id);

static const struct of_device_id max30100_dt_ids[] = {
        { .compatible = "maxim,max30100" },
        { }
};
MODULE_DEVICE_TABLE(of, max30100_dt_ids);

static struct i2c_driver max30100_driver = {
        .driver = {
                .name   = MAX30100_DRV_NAME,
                .of_match_table = max30100_dt_ids,
        },
        .probe          = max30100_probe,
        .remove         = max30100_remove,
        .id_table       = max30100_id,
};
module_i2c_driver(max30100_driver);

MODULE_AUTHOR("Matt Ranostay <matt.ranostay@konsulko.com>");
MODULE_DESCRIPTION("MAX30100 heart rate and pulse oximeter sensor");
MODULE_LICENSE("GPL");