// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
/*
 * Support for ST VL53L1X FlightSense ToF Ranging Sensor on a i2c bus.
 *
 * Copyright (C) 2026 Siratul Islam <email@sirat.me>
 *
 * Datasheet available at
 * <https://www.st.com/resource/en/datasheet/vl53l1x.pdf>
 *
 * Default 7-bit i2c slave address 0x29.
 *
 * The VL53L1X requires a firmware configuration blob to be loaded at boot.
 * Register values for the default configuration are taken from
 * ST's VL53L1X Ultra Lite Driver (STSW-IMG009).
 */

#include <linux/array_size.h>
#include <linux/bits.h>
#include <linux/bitfield.h>
#include <linux/completion.h>
#include <linux/delay.h>
#include <linux/dev_printk.h>
#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/math.h>
#include <linux/module.h>
#include <linux/regmap.h>
#include <linux/regulator/consumer.h>
#include <linux/reset.h>
#include <linux/time.h>
#include <linux/types.h>

#include <asm/byteorder.h>

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

#define VL53L1X_REG_SOFT_RESET                                          0x0000
#define VL53L1X_REG_VHV_CONFIG__TIMEOUT_MACROP_LOOP_BOUND               0x0008
#define VL53L1X_REG_VHV_CONFIG__INIT                                    0x000B
#define VL53L1X_REG_GPIO_HV_MUX__CTRL                                   0x0030
#define VL53L1X_REG_GPIO__TIO_HV_STATUS                                 0x0031
#define VL53L1X_REG_SYSTEM__INTERRUPT_CONFIG_GPIO                       0x0046
#define VL53L1X_REG_PHASECAL_CONFIG__TIMEOUT_MACROP                     0x004B
#define VL53L1X_REG_RANGE_CONFIG__TIMEOUT_MACROP_A                      0x005E
#define VL53L1X_REG_RANGE_CONFIG__VCSEL_PERIOD_A                        0x0060
#define VL53L1X_REG_RANGE_CONFIG__TIMEOUT_MACROP_B                      0x0061
#define VL53L1X_REG_RANGE_CONFIG__VCSEL_PERIOD_B                        0x0063
#define VL53L1X_REG_RANGE_CONFIG__VALID_PHASE_HIGH                      0x0069
#define VL53L1X_REG_SYSTEM__INTERMEASUREMENT_PERIOD                     0x006C
#define VL53L1X_REG_SD_CONFIG__WOI_SD0                                  0x0078
#define VL53L1X_REG_SD_CONFIG__WOI_SD1                                  0x0079
#define VL53L1X_REG_SD_CONFIG__INITIAL_PHASE_SD0                        0x007A
#define VL53L1X_REG_SD_CONFIG__INITIAL_PHASE_SD1                        0x007B
#define VL53L1X_REG_SYSTEM__INTERRUPT_CLEAR                             0x0086
#define VL53L1X_REG_SYSTEM__MODE_START                                  0x0087
#define VL53L1X_REG_RESULT__RANGE_STATUS                                0x0089
#define VL53L1X_REG_RESULT__FINAL_CROSSTALK_CORRECTED_RANGE_MM_SD0      0x0096
#define VL53L1X_REG_RESULT__OSC_CALIBRATE_VAL                           0x00DE
#define VL53L1X_REG_FIRMWARE__SYSTEM_STATUS                             0x00E5
#define VL53L1X_REG_IDENTIFICATION__MODEL_ID                            0x010F
#define VL53L1X_REG_DEFAULT_CONFIG                                      0x002D

#define VL53L1X_MODEL_ID_VAL            0xEACC

#define VL53L1X_MODE_START_TIMED        0x40
#define VL53L1X_MODE_START_STOP         0x00

#define VL53L1X_INT_NEW_SAMPLE_READY    0x02

#define VL53L1X_GPIO_HV_MUX_POLARITY    BIT(4)

#define VL53L1X_VHV_LOOP_BOUND_TWO      0x09

#define VL53L1X_RANGE_STATUS_MASK       GENMASK(4, 0)
#define VL53L1X_RANGE_STATUS_VALID      9

#define VL53L1X_OSC_CALIBRATE_MASK      GENMASK(9, 0)

/* Inter-measurement period uses PLL divider with 1.075 oscillator correction */
static const struct u32_fract vl53l1x_osc_correction = {
        .numerator = 1075,
        .denominator = 1000,
};

enum vl53l1x_distance_mode {
        VL53L1X_SHORT,
        VL53L1X_LONG,
};

struct vl53l1x_data {
        struct regmap *regmap;
        struct completion completion;
        struct reset_control *xshut_reset;
        enum vl53l1x_distance_mode distance_mode;
        u8 gpio_polarity;
        int irq;
};

static const struct regmap_range vl53l1x_volatile_ranges[] = {
        regmap_reg_range(VL53L1X_REG_GPIO__TIO_HV_STATUS,
                         VL53L1X_REG_GPIO__TIO_HV_STATUS),
        regmap_reg_range(VL53L1X_REG_RESULT__RANGE_STATUS,
                         VL53L1X_REG_RESULT__RANGE_STATUS),
        regmap_reg_range(VL53L1X_REG_RESULT__FINAL_CROSSTALK_CORRECTED_RANGE_MM_SD0,
                         VL53L1X_REG_RESULT__FINAL_CROSSTALK_CORRECTED_RANGE_MM_SD0 + 1),
        regmap_reg_range(VL53L1X_REG_RESULT__OSC_CALIBRATE_VAL,
                         VL53L1X_REG_RESULT__OSC_CALIBRATE_VAL + 1),
        regmap_reg_range(VL53L1X_REG_FIRMWARE__SYSTEM_STATUS,
                         VL53L1X_REG_FIRMWARE__SYSTEM_STATUS),
};

static const struct regmap_access_table vl53l1x_volatile_table = {
        .yes_ranges = vl53l1x_volatile_ranges,
        .n_yes_ranges = ARRAY_SIZE(vl53l1x_volatile_ranges),
};

static const struct regmap_range vl53l1x_write_only_ranges[] = {
        regmap_reg_range(VL53L1X_REG_SOFT_RESET, VL53L1X_REG_SOFT_RESET),
        regmap_reg_range(VL53L1X_REG_SYSTEM__INTERRUPT_CLEAR,
                         VL53L1X_REG_SYSTEM__MODE_START),
};

static const struct regmap_access_table vl53l1x_readable_table = {
        .no_ranges = vl53l1x_write_only_ranges,
        .n_no_ranges = ARRAY_SIZE(vl53l1x_write_only_ranges),
};

static const struct regmap_config vl53l1x_regmap_config = {
        .reg_bits = 16,
        .val_bits = 8,
        /* MODEL_ID is 16-bit. +1 covers the second byte at 0x0110 */
        .max_register = VL53L1X_REG_IDENTIFICATION__MODEL_ID + 1,
        .cache_type = REGCACHE_MAPLE,
        .volatile_table = &vl53l1x_volatile_table,
        .rd_table = &vl53l1x_readable_table,
};

static int vl53l1x_read_u16(struct vl53l1x_data *data, u16 reg, u16 *val)
{
        __be16 buf;
        int ret;

        ret = regmap_bulk_read(data->regmap, reg, &buf, sizeof(buf));
        if (ret)
                return ret;

        *val = be16_to_cpu(buf);
        return 0;
}

static int vl53l1x_write_u16(struct vl53l1x_data *data, u16 reg, u16 val)
{
        __be16 buf = cpu_to_be16(val);

        return regmap_bulk_write(data->regmap, reg, &buf, sizeof(buf));
}

static int vl53l1x_write_u32(struct vl53l1x_data *data, u16 reg, u32 val)
{
        __be32 buf = cpu_to_be32(val);

        return regmap_bulk_write(data->regmap, reg, &buf, sizeof(buf));
}

static int vl53l1x_clear_irq(struct vl53l1x_data *data)
{
        return regmap_write(data->regmap, VL53L1X_REG_SYSTEM__INTERRUPT_CLEAR, 0x01);
}

static int vl53l1x_start_ranging(struct vl53l1x_data *data)
{
        int ret;

        ret = vl53l1x_clear_irq(data);
        if (ret)
                return ret;

        return regmap_write(data->regmap, VL53L1X_REG_SYSTEM__MODE_START,
                            VL53L1X_MODE_START_TIMED);
}

static int vl53l1x_stop_ranging(struct vl53l1x_data *data)
{
        return regmap_write(data->regmap, VL53L1X_REG_SYSTEM__MODE_START,
                            VL53L1X_MODE_START_STOP);
}

/*
 * Default configuration blob from ST's VL53L1X Ultra Lite Driver
 * (STSW-IMG009).
 */
static const u8 vl53l1x_default_config[] = {
        0x00, 0x00, 0x00, 0x01, 0x02, 0x00, 0x02, 0x08, /* reg 0x2d..0x34 */
        0x00, 0x08, 0x10, 0x01, 0x01, 0x00, 0x00, 0x00, /* reg 0x35..0x3c */
        0x00, 0xFF, 0x00, 0x0F, 0x00, 0x00, 0x00, 0x00, /* reg 0x3d..0x44 */
        0x00, 0x20, 0x0B, 0x00, 0x00, 0x02, 0x0A, 0x21, /* reg 0x45..0x4c */
        0x00, 0x00, 0x05, 0x00, 0x00, 0x00, 0x00, 0xC8, /* reg 0x4d..0x54 */
        0x00, 0x00, 0x38, 0xFF, 0x01, 0x00, 0x08, 0x00, /* reg 0x55..0x5c */
        0x00, 0x01, 0xCC, 0x0F, 0x01, 0xF1, 0x0D, 0x01, /* reg 0x5d..0x64 */
        0x68, 0x00, 0x80, 0x08, 0xB8, 0x00, 0x00, 0x00, /* reg 0x65..0x6c */
        0x00, 0x0F, 0x89, 0x00, 0x00, 0x00, 0x00, 0x00, /* reg 0x6d..0x74 */
        0x00, 0x00, 0x01, 0x0F, 0x0D, 0x0E, 0x0E, 0x00, /* reg 0x75..0x7c */
        0x00, 0x02, 0xC7, 0xFF, 0x9B, 0x00, 0x00, 0x00, /* reg 0x7d..0x84 */
        0x01, 0x00, 0x00,                               /* reg 0x85..0x87 */
};

static int vl53l1x_chip_init(struct vl53l1x_data *data)
{
        struct device *dev = regmap_get_device(data->regmap);
        unsigned int val;
        u16 model_id;
        int ret;

        if (!data->xshut_reset) {
                ret = regmap_write(data->regmap, VL53L1X_REG_SOFT_RESET, 0x00);
                if (ret)
                        return ret;
                fsleep(100); /* conservative reset pulse, no spec */

                ret = regmap_write(data->regmap, VL53L1X_REG_SOFT_RESET, 0x01);
                if (ret)
                        return ret;
                fsleep(1000); /* conservative boot wait, no spec */
        }

        ret = regmap_read_poll_timeout(data->regmap,
                                       VL53L1X_REG_FIRMWARE__SYSTEM_STATUS, val,
                                       val & BIT(0),
                                       1 * USEC_PER_MSEC,
                                       100 * USEC_PER_MSEC);
        if (ret)
                return dev_err_probe(dev, ret, "firmware boot timeout\n");

        ret = vl53l1x_read_u16(data, VL53L1X_REG_IDENTIFICATION__MODEL_ID,
                               &model_id);
        if (ret)
                return ret;

        if (model_id != VL53L1X_MODEL_ID_VAL)
                dev_info(dev, "unknown model id: 0x%04x, continuing\n", model_id);

        ret = regmap_bulk_write(data->regmap, VL53L1X_REG_DEFAULT_CONFIG,
                                vl53l1x_default_config,
                                sizeof(vl53l1x_default_config));
        if (ret)
                return ret;

        ret = regmap_read(data->regmap, VL53L1X_REG_GPIO_HV_MUX__CTRL, &val);
        if (ret)
                return ret;
        data->gpio_polarity = !!(val & VL53L1X_GPIO_HV_MUX_POLARITY);

        /* Initial ranging cycle for VHV calibration */
        ret = vl53l1x_start_ranging(data);
        if (ret)
                return ret;

        /* 1ms poll, 1s timeout covers max timing budgets (per ST Ultra Lite Driver) */
        ret = regmap_read_poll_timeout(data->regmap,
                                       VL53L1X_REG_GPIO__TIO_HV_STATUS, val,
                                       (val & 1) != data->gpio_polarity,
                                       1 * USEC_PER_MSEC,
                                       1000 * USEC_PER_MSEC);
        if (ret)
                return ret;

        ret = vl53l1x_clear_irq(data);
        if (ret)
                return ret;

        ret = vl53l1x_stop_ranging(data);
        if (ret)
                return ret;

        ret = regmap_write(data->regmap,
                           VL53L1X_REG_VHV_CONFIG__TIMEOUT_MACROP_LOOP_BOUND,
                           VL53L1X_VHV_LOOP_BOUND_TWO);
        if (ret)
                return ret;

        return regmap_write(data->regmap, VL53L1X_REG_VHV_CONFIG__INIT, 0x00);
}

static const struct reg_sequence vl53l1x_mode_short[] = {
        { VL53L1X_REG_PHASECAL_CONFIG__TIMEOUT_MACROP,          0x14 },
        { VL53L1X_REG_RANGE_CONFIG__VCSEL_PERIOD_A,             0x07 },
        { VL53L1X_REG_RANGE_CONFIG__VCSEL_PERIOD_B,             0x05 },
        { VL53L1X_REG_RANGE_CONFIG__VALID_PHASE_HIGH,           0x38 },
        { VL53L1X_REG_SD_CONFIG__WOI_SD0,                       0x07 },
        { VL53L1X_REG_SD_CONFIG__WOI_SD1,                       0x05 },
        { VL53L1X_REG_SD_CONFIG__INITIAL_PHASE_SD0,             0x06 },
        { VL53L1X_REG_SD_CONFIG__INITIAL_PHASE_SD1,             0x06 },
};

static const struct reg_sequence vl53l1x_mode_long[] = {
        { VL53L1X_REG_PHASECAL_CONFIG__TIMEOUT_MACROP,          0x0A },
        { VL53L1X_REG_RANGE_CONFIG__VCSEL_PERIOD_A,             0x0F },
        { VL53L1X_REG_RANGE_CONFIG__VCSEL_PERIOD_B,             0x0D },
        { VL53L1X_REG_RANGE_CONFIG__VALID_PHASE_HIGH,           0xB8 },
        { VL53L1X_REG_SD_CONFIG__WOI_SD0,                       0x0F },
        { VL53L1X_REG_SD_CONFIG__WOI_SD1,                       0x0D },
        { VL53L1X_REG_SD_CONFIG__INITIAL_PHASE_SD0,             0x0E },
        { VL53L1X_REG_SD_CONFIG__INITIAL_PHASE_SD1,             0x0E },
};

static const struct {
        const struct reg_sequence *regs;
        size_t num_regs;
} vl53l1x_mode_configs[] = {
        [VL53L1X_SHORT] = { vl53l1x_mode_short, ARRAY_SIZE(vl53l1x_mode_short) },
        [VL53L1X_LONG]  = { vl53l1x_mode_long, ARRAY_SIZE(vl53l1x_mode_long) },
};

static int vl53l1x_set_distance_mode(struct vl53l1x_data *data,
                                     enum vl53l1x_distance_mode mode)
{
        int ret;

        if (mode >= ARRAY_SIZE(vl53l1x_mode_configs))
                return -EINVAL;

        ret = regmap_multi_reg_write(data->regmap,
                                     vl53l1x_mode_configs[mode].regs,
                                     vl53l1x_mode_configs[mode].num_regs);
        if (ret)
                return ret;

        data->distance_mode = mode;
        return 0;
}

/*
 * The timing budget controls how long the sensor spends collecting
 * a single range measurement. Pre-computed TIMEOUT_MACROP register
 * values from ST's VL53L1X Ultra Lite Driver.
 */
static int vl53l1x_set_timing_budget(struct vl53l1x_data *data, u16 budget_ms)
{
        u16 timeout_a, timeout_b;
        int ret;

        switch (data->distance_mode) {
        case VL53L1X_SHORT:
                switch (budget_ms) {
                case 15:
                        timeout_a = 0x001D;
                        timeout_b = 0x0027;
                        break;
                case 20:
                        timeout_a = 0x0051;
                        timeout_b = 0x006E;
                        break;
                case 33:
                        timeout_a = 0x00D6;
                        timeout_b = 0x006E;
                        break;
                case 50:
                        timeout_a = 0x01AE;
                        timeout_b = 0x01E8;
                        break;
                case 100:
                        timeout_a = 0x02E1;
                        timeout_b = 0x0388;
                        break;
                case 200:
                        timeout_a = 0x03E1;
                        timeout_b = 0x0496;
                        break;
                case 500:
                        timeout_a = 0x0591;
                        timeout_b = 0x05C1;
                        break;
                default:
                        return -EINVAL;
                }
                break;
        case VL53L1X_LONG:
                switch (budget_ms) {
                case 20:
                        timeout_a = 0x001E;
                        timeout_b = 0x0022;
                        break;
                case 33:
                        timeout_a = 0x0060;
                        timeout_b = 0x006E;
                        break;
                case 50:
                        timeout_a = 0x00AD;
                        timeout_b = 0x00C6;
                        break;
                case 100:
                        timeout_a = 0x01CC;
                        timeout_b = 0x01EA;
                        break;
                case 200:
                        timeout_a = 0x02D9;
                        timeout_b = 0x02F8;
                        break;
                case 500:
                        timeout_a = 0x048F;
                        timeout_b = 0x04A4;
                        break;
                default:
                        return -EINVAL;
                }
                break;
        default:
                return -EINVAL;
        }

        ret = vl53l1x_write_u16(data, VL53L1X_REG_RANGE_CONFIG__TIMEOUT_MACROP_A,
                                timeout_a);
        if (ret)
                return ret;

        return vl53l1x_write_u16(data, VL53L1X_REG_RANGE_CONFIG__TIMEOUT_MACROP_B,
                                 timeout_b);
}

static int vl53l1x_set_inter_measurement_ms(struct vl53l1x_data *data,
                                            u16 period_ms)
{
        u16 osc_calibrate_val;
        u16 clock_pll;
        u32 inter_meas;
        int ret;

        ret = vl53l1x_read_u16(data, VL53L1X_REG_RESULT__OSC_CALIBRATE_VAL,
                               &osc_calibrate_val);
        if (ret)
                return ret;

        clock_pll = osc_calibrate_val & VL53L1X_OSC_CALIBRATE_MASK;
        inter_meas = (clock_pll * period_ms * vl53l1x_osc_correction.numerator) /
                     vl53l1x_osc_correction.denominator;

        return vl53l1x_write_u32(data,
                                 VL53L1X_REG_SYSTEM__INTERMEASUREMENT_PERIOD,
                                 inter_meas);
}

static int vl53l1x_read_proximity(struct vl53l1x_data *data, int *val)
{
        unsigned int range_status;
        u16 distance;
        int ret;

        if (data->irq) {
                reinit_completion(&data->completion);

                ret = vl53l1x_clear_irq(data);
                if (ret)
                        return ret;

                if (!wait_for_completion_timeout(&data->completion, HZ))
                        return -ETIMEDOUT;
        } else {
                unsigned int rdy;

                /* 1ms poll, 1s timeout covers max timing budgets (per ST Ultra Lite Driver) */
                ret = regmap_read_poll_timeout(data->regmap,
                                               VL53L1X_REG_GPIO__TIO_HV_STATUS, rdy,
                                               (rdy & 1) != data->gpio_polarity,
                                               1 * USEC_PER_MSEC,
                                               1000 * USEC_PER_MSEC);
                if (ret)
                        return ret;
        }

        ret = regmap_read(data->regmap, VL53L1X_REG_RESULT__RANGE_STATUS,
                          &range_status);
        if (ret)
                goto clear_irq;

        if (FIELD_GET(VL53L1X_RANGE_STATUS_MASK, range_status) !=
            VL53L1X_RANGE_STATUS_VALID) {
                ret = -EIO;
                goto clear_irq;
        }

        ret = vl53l1x_read_u16(data,
                               VL53L1X_REG_RESULT__FINAL_CROSSTALK_CORRECTED_RANGE_MM_SD0,
                               &distance);
        if (ret)
                goto clear_irq;

        *val = distance;

clear_irq:
        vl53l1x_clear_irq(data);
        return ret;
}

static const struct iio_chan_spec vl53l1x_channels[] = {
        {
                .type = IIO_DISTANCE,
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
                                      BIT(IIO_CHAN_INFO_SCALE),
                .scan_index = 0,
                .scan_type = {
                        .sign = 'u',
                        .realbits = 16,
                        .storagebits = 16,
                },
        },
        IIO_CHAN_SOFT_TIMESTAMP(1),
};

static int vl53l1x_read_raw(struct iio_dev *indio_dev,
                            const struct iio_chan_spec *chan,
                            int *val, int *val2, long mask)
{
        struct vl53l1x_data *data = iio_priv(indio_dev);
        int ret;

        if (chan->type != IIO_DISTANCE)
                return -EINVAL;

        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                if (!iio_device_claim_direct(indio_dev))
                        return -EBUSY;
                ret = vl53l1x_read_proximity(data, val);
                iio_device_release_direct(indio_dev);
                if (ret)
                        return ret;
                return IIO_VAL_INT;
        case IIO_CHAN_INFO_SCALE:
                *val = 0;
                *val2 = 1000;
                return IIO_VAL_INT_PLUS_MICRO;
        default:
                return -EINVAL;
        }
}

static const struct iio_info vl53l1x_info = {
        .read_raw = vl53l1x_read_raw,
        .validate_trigger = iio_validate_own_trigger,
};

static irqreturn_t vl53l1x_trigger_handler(int irq, void *priv)
{
        struct iio_poll_func *pf = priv;
        struct iio_dev *indio_dev = pf->indio_dev;
        struct vl53l1x_data *data = iio_priv(indio_dev);
        struct {
                u16 distance;
                aligned_s64 timestamp;
        } scan = { };
        unsigned int range_status;
        int ret;

        ret = regmap_read(data->regmap, VL53L1X_REG_RESULT__RANGE_STATUS,
                          &range_status);
        if (ret)
                goto notify_and_clear_irq;
        if (FIELD_GET(VL53L1X_RANGE_STATUS_MASK, range_status) !=
                      VL53L1X_RANGE_STATUS_VALID)
                goto notify_and_clear_irq;

        ret = vl53l1x_read_u16(data,
                               VL53L1X_REG_RESULT__FINAL_CROSSTALK_CORRECTED_RANGE_MM_SD0,
                               &scan.distance);
        if (ret)
                goto notify_and_clear_irq;

        iio_push_to_buffers_with_ts(indio_dev, &scan, sizeof(scan),
                                    iio_get_time_ns(indio_dev));

notify_and_clear_irq:
        iio_trigger_notify_done(indio_dev->trig);
        vl53l1x_clear_irq(data);

        return IRQ_HANDLED;
}

static irqreturn_t vl53l1x_irq_handler(int irq, void *priv)
{
        struct iio_dev *indio_dev = priv;
        struct vl53l1x_data *data = iio_priv(indio_dev);

        if (iio_buffer_enabled(indio_dev))
                iio_trigger_poll(indio_dev->trig);
        else
                complete(&data->completion);

        return IRQ_HANDLED;
}

static const struct iio_trigger_ops vl53l1x_trigger_ops = {
        .validate_device = iio_trigger_validate_own_device,
};

static void vl53l1x_stop_ranging_action(void *priv)
{
        vl53l1x_stop_ranging(priv);
}

static int vl53l1x_configure_irq(struct device *dev, int irq,
                                 struct iio_dev *indio_dev)
{
        struct vl53l1x_data *data = iio_priv(indio_dev);
        int ret;

        ret = devm_request_irq(dev, irq, vl53l1x_irq_handler, IRQF_NO_THREAD,
                               indio_dev->name, indio_dev);
        if (ret)
                return ret;

        ret = regmap_write(data->regmap, VL53L1X_REG_SYSTEM__INTERRUPT_CONFIG_GPIO,
                           VL53L1X_INT_NEW_SAMPLE_READY);
        if (ret)
                return dev_err_probe(dev, ret, "failed to configure IRQ\n");

        return 0;
}

static int vl53l1x_probe(struct i2c_client *client)
{
        struct device *dev = &client->dev;
        struct vl53l1x_data *data;
        struct iio_dev *indio_dev;
        int ret;

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

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

        data->regmap = devm_regmap_init_i2c(client, &vl53l1x_regmap_config);
        if (IS_ERR(data->regmap))
                return dev_err_probe(dev, PTR_ERR(data->regmap),
                                     "regmap initialization failed\n");

        ret = devm_regulator_get_enable(dev, "vdd");
        if (ret)
                return dev_err_probe(dev, ret, "Failed to enable VDD regulator\n");

        /*
         * XSHUT held low puts the chip in hardware standby. All register
         * state is lost on de-assert so this is functionally a reset.
         */
        data->xshut_reset = devm_reset_control_get_optional_exclusive_deasserted(dev, NULL);
        if (IS_ERR(data->xshut_reset))
                return dev_err_probe(dev, PTR_ERR(data->xshut_reset),
                                     "Cannot get reset control\n");

        /*
         * 1.2 ms max boot duration.
         * Datasheet Section 3.6 "Power up and boot sequence".
         */
        fsleep(1200);

        ret = vl53l1x_chip_init(data);
        if (ret)
                return ret;

        ret = vl53l1x_set_distance_mode(data, VL53L1X_LONG);
        if (ret)
                return ret;

        /* 50 ms timing budget (per ST Ultra Lite Driver) */
        ret = vl53l1x_set_timing_budget(data, 50);
        if (ret)
                return ret;

        /* 50 ms inter-measurement period (per ST Ultra Lite Driver) */
        ret = vl53l1x_set_inter_measurement_ms(data, 50);
        if (ret)
                return ret;

        /*
         * The hardware only supports "autonomous" continuous ranging mode.
         * Start ranging here and leave it running for the lifetime of
         * the device. Both direct reads and the buffer path rely on this.
         */
        ret = vl53l1x_start_ranging(data);
        if (ret)
                return ret;

        ret = devm_add_action_or_reset(dev, vl53l1x_stop_ranging_action, data);
        if (ret)
                return ret;

        indio_dev->name = "vl53l1x";
        indio_dev->info = &vl53l1x_info;
        indio_dev->channels = vl53l1x_channels;
        indio_dev->num_channels = ARRAY_SIZE(vl53l1x_channels);
        indio_dev->modes = INDIO_DIRECT_MODE;

        if (client->irq) {
                struct iio_trigger *trig;

                init_completion(&data->completion);

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

                trig->ops = &vl53l1x_trigger_ops;
                iio_trigger_set_drvdata(trig, indio_dev);
                ret = devm_iio_trigger_register(dev, trig);
                if (ret)
                        return ret;

                indio_dev->trig = iio_trigger_get(trig);

                ret = vl53l1x_configure_irq(dev, client->irq, indio_dev);
                if (ret)
                        return ret;

                ret = devm_iio_triggered_buffer_setup(dev, indio_dev, NULL,
                                                      &vl53l1x_trigger_handler,
                                                      NULL);
                if (ret)
                        return ret;
        }

        return devm_iio_device_register(dev, indio_dev);
}

static const struct i2c_device_id vl53l1x_id[] = {
        { .name = "vl53l1x" },
        { }
};
MODULE_DEVICE_TABLE(i2c, vl53l1x_id);

static const struct of_device_id st_vl53l1x_dt_match[] = {
        { .compatible = "st,vl53l1x" },
        { }
};
MODULE_DEVICE_TABLE(of, st_vl53l1x_dt_match);

static struct i2c_driver vl53l1x_driver = {
        .driver = {
                .name = "vl53l1x-i2c",
                .of_match_table = st_vl53l1x_dt_match,
        },
        .probe = vl53l1x_probe,
        .id_table = vl53l1x_id,
};
module_i2c_driver(vl53l1x_driver);

MODULE_AUTHOR("Siratul Islam <email@sirat.me>");
MODULE_DESCRIPTION("ST VL53L1X ToF ranging sensor driver");
MODULE_LICENSE("Dual BSD/GPL");