// SPDX-License-Identifier: GPL-2.0-only
/*
 * Driver for the Asahi Kasei EMD Corporation AK8974
 * and Aichi Steel AMI305 magnetometer chips.
 * Based on a patch from Samu Onkalo and the AK8975 IIO driver.
 *
 * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
 * Copyright (c) 2010 NVIDIA Corporation.
 * Copyright (C) 2016 Linaro Ltd.
 *
 * Author: Samu Onkalo <samu.p.onkalo@nokia.com>
 * Author: Linus Walleij <linus.walleij@linaro.org>
 */
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/kernel.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/irq.h> /* For irq_get_irq_data() */
#include <linux/completion.h>
#include <linux/err.h>
#include <linux/mutex.h>
#include <linux/delay.h>
#include <linux/bitops.h>
#include <linux/random.h>
#include <linux/regmap.h>
#include <linux/regulator/consumer.h>
#include <linux/pm_runtime.h>

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

/*
 * 16-bit registers are little-endian. LSB is at the address defined below
 * and MSB is at the next higher address.
 */

/* These registers are common for AK8974 and AMI30x */
#define AK8974_SELFTEST         0x0C
#define AK8974_SELFTEST_IDLE    0x55
#define AK8974_SELFTEST_OK      0xAA

#define AK8974_INFO             0x0D

#define AK8974_WHOAMI           0x0F
#define AK8974_WHOAMI_VALUE_AMI306 0x46
#define AK8974_WHOAMI_VALUE_AMI305 0x47
#define AK8974_WHOAMI_VALUE_AK8974 0x48
#define AK8974_WHOAMI_VALUE_HSCDTD008A 0x49

#define AK8974_DATA_X           0x10
#define AK8974_DATA_Y           0x12
#define AK8974_DATA_Z           0x14
#define AK8974_INT_SRC          0x16
#define AK8974_STATUS           0x18
#define AK8974_INT_CLEAR        0x1A
#define AK8974_CTRL1            0x1B
#define AK8974_CTRL2            0x1C
#define AK8974_CTRL3            0x1D
#define AK8974_INT_CTRL         0x1E
#define AK8974_INT_THRES        0x26  /* Absolute any axis value threshold */
#define AK8974_PRESET           0x30

/* AK8974-specific offsets */
#define AK8974_OFFSET_X         0x20
#define AK8974_OFFSET_Y         0x22
#define AK8974_OFFSET_Z         0x24
/* AMI305-specific offsets */
#define AMI305_OFFSET_X         0x6C
#define AMI305_OFFSET_Y         0x72
#define AMI305_OFFSET_Z         0x78

/* Different temperature registers */
#define AK8974_TEMP             0x31
#define AMI305_TEMP             0x60

/* AMI306-specific control register */
#define AMI306_CTRL4            0x5C

/* AMI306 factory calibration data */

/* fine axis sensitivity */
#define AMI306_FINEOUTPUT_X     0x90
#define AMI306_FINEOUTPUT_Y     0x92
#define AMI306_FINEOUTPUT_Z     0x94

/* axis sensitivity */
#define AMI306_SENS_X           0x96
#define AMI306_SENS_Y           0x98
#define AMI306_SENS_Z           0x9A

/* axis cross-interference */
#define AMI306_GAIN_PARA_XZ     0x9C
#define AMI306_GAIN_PARA_XY     0x9D
#define AMI306_GAIN_PARA_YZ     0x9E
#define AMI306_GAIN_PARA_YX     0x9F
#define AMI306_GAIN_PARA_ZY     0xA0
#define AMI306_GAIN_PARA_ZX     0xA1

/* offset at ZERO magnetic field */
#define AMI306_OFFZERO_X        0xF8
#define AMI306_OFFZERO_Y        0xFA
#define AMI306_OFFZERO_Z        0xFC


#define AK8974_INT_X_HIGH       BIT(7) /* Axis over +threshold  */
#define AK8974_INT_Y_HIGH       BIT(6)
#define AK8974_INT_Z_HIGH       BIT(5)
#define AK8974_INT_X_LOW        BIT(4) /* Axis below -threshold */
#define AK8974_INT_Y_LOW        BIT(3)
#define AK8974_INT_Z_LOW        BIT(2)
#define AK8974_INT_RANGE        BIT(1) /* Range overflow (any axis) */

#define AK8974_STATUS_DRDY      BIT(6) /* Data ready */
#define AK8974_STATUS_OVERRUN   BIT(5) /* Data overrun */
#define AK8974_STATUS_INT       BIT(4) /* Interrupt occurred */

#define AK8974_CTRL1_POWER      BIT(7) /* 0 = standby; 1 = active */
#define AK8974_CTRL1_RATE       BIT(4) /* 0 = 10 Hz; 1 = 20 Hz   */
#define AK8974_CTRL1_FORCE_EN   BIT(1) /* 0 = normal; 1 = force  */
#define AK8974_CTRL1_MODE2      BIT(0) /* 0 */

#define AK8974_CTRL2_INT_EN     BIT(4)  /* 1 = enable interrupts              */
#define AK8974_CTRL2_DRDY_EN    BIT(3)  /* 1 = enable data ready signal */
#define AK8974_CTRL2_DRDY_POL   BIT(2)  /* 1 = data ready active high   */
#define AK8974_CTRL2_RESDEF     (AK8974_CTRL2_DRDY_POL)

#define AK8974_CTRL3_RESET      BIT(7) /* Software reset                  */
#define AK8974_CTRL3_FORCE      BIT(6) /* Start forced measurement */
#define AK8974_CTRL3_SELFTEST   BIT(4) /* Set selftest register   */
#define AK8974_CTRL3_RESDEF     0x00

#define AK8974_INT_CTRL_XEN     BIT(7) /* Enable interrupt for this axis */
#define AK8974_INT_CTRL_YEN     BIT(6)
#define AK8974_INT_CTRL_ZEN     BIT(5)
#define AK8974_INT_CTRL_XYZEN   (BIT(7)|BIT(6)|BIT(5))
#define AK8974_INT_CTRL_POL     BIT(3) /* 0 = active low; 1 = active high */
#define AK8974_INT_CTRL_PULSE   BIT(1) /* 0 = latched; 1 = pulse (50 usec) */
#define AK8974_INT_CTRL_RESDEF  (AK8974_INT_CTRL_XYZEN | AK8974_INT_CTRL_POL)

/* HSCDTD008A-specific control register */
#define HSCDTD008A_CTRL4        0x1E
#define HSCDTD008A_CTRL4_MMD    BIT(7)  /* must be set to 1 */
#define HSCDTD008A_CTRL4_RANGE  BIT(4)  /* 0 = 14-bit output; 1 = 15-bit output */
#define HSCDTD008A_CTRL4_RESDEF (HSCDTD008A_CTRL4_MMD | HSCDTD008A_CTRL4_RANGE)

/* The AMI305 has elaborate FW version and serial number registers */
#define AMI305_VER              0xE8
#define AMI305_SN               0xEA

#define AK8974_MAX_RANGE        2048

#define AK8974_POWERON_DELAY    50
#define AK8974_ACTIVATE_DELAY   1
#define AK8974_SELFTEST_DELAY   1
/*
 * Set the autosuspend to two orders of magnitude larger than the poweron
 * delay to make sane reasonable power tradeoff savings (5 seconds in
 * this case).
 */
#define AK8974_AUTOSUSPEND_DELAY 5000

#define AK8974_MEASTIME         3

#define AK8974_PWR_ON           1
#define AK8974_PWR_OFF          0

/**
 * struct ak8974 - state container for the AK8974 driver
 * @i2c: parent I2C client
 * @orientation: mounting matrix, flipped axis etc
 * @map: regmap to access the AK8974 registers over I2C
 * @regs: the avdd and dvdd power regulators
 * @name: the name of the part
 * @variant: the whoami ID value (for selecting code paths)
 * @lock: locks the magnetometer for exclusive use during a measurement
 * @drdy_irq: uses the DRDY IRQ line
 * @drdy_complete: completion for DRDY
 * @drdy_active_low: the DRDY IRQ is active low
 * @scan: timestamps
 */
struct ak8974 {
        struct i2c_client *i2c;
        struct iio_mount_matrix orientation;
        struct regmap *map;
        struct regulator_bulk_data regs[2];
        const char *name;
        u8 variant;
        struct mutex lock;
        bool drdy_irq;
        struct completion drdy_complete;
        bool drdy_active_low;
        /* Ensure timestamp is naturally aligned */
        struct {
                __le16 channels[3];
                aligned_s64 ts;
        } scan;
};

static const char ak8974_reg_avdd[] = "avdd";
static const char ak8974_reg_dvdd[] = "dvdd";

static int ak8974_get_u16_val(struct ak8974 *ak8974, u8 reg, u16 *val)
{
        int ret;
        __le16 bulk;

        ret = regmap_bulk_read(ak8974->map, reg, &bulk, 2);
        if (ret)
                return ret;
        *val = le16_to_cpu(bulk);

        return 0;
}

static int ak8974_set_u16_val(struct ak8974 *ak8974, u8 reg, u16 val)
{
        __le16 bulk = cpu_to_le16(val);

        return regmap_bulk_write(ak8974->map, reg, &bulk, 2);
}

static int ak8974_set_power(struct ak8974 *ak8974, bool mode)
{
        int ret;
        u8 val;

        val = mode ? AK8974_CTRL1_POWER : 0;
        val |= AK8974_CTRL1_FORCE_EN;
        ret = regmap_write(ak8974->map, AK8974_CTRL1, val);
        if (ret < 0)
                return ret;

        if (mode)
                msleep(AK8974_ACTIVATE_DELAY);

        return 0;
}

static int ak8974_reset(struct ak8974 *ak8974)
{
        int ret;

        /* Power on to get register access. Sets CTRL1 reg to reset state */
        ret = ak8974_set_power(ak8974, AK8974_PWR_ON);
        if (ret)
                return ret;
        ret = regmap_write(ak8974->map, AK8974_CTRL2, AK8974_CTRL2_RESDEF);
        if (ret)
                return ret;
        ret = regmap_write(ak8974->map, AK8974_CTRL3, AK8974_CTRL3_RESDEF);
        if (ret)
                return ret;
        if (ak8974->variant != AK8974_WHOAMI_VALUE_HSCDTD008A) {
                ret = regmap_write(ak8974->map, AK8974_INT_CTRL,
                                   AK8974_INT_CTRL_RESDEF);
                if (ret)
                        return ret;
        } else {
                ret = regmap_write(ak8974->map, HSCDTD008A_CTRL4,
                                   HSCDTD008A_CTRL4_RESDEF);
                if (ret)
                        return ret;
        }

        /* After reset, power off is default state */
        return ak8974_set_power(ak8974, AK8974_PWR_OFF);
}

static int ak8974_configure(struct ak8974 *ak8974)
{
        int ret;

        ret = regmap_write(ak8974->map, AK8974_CTRL2, AK8974_CTRL2_DRDY_EN |
                           AK8974_CTRL2_INT_EN);
        if (ret)
                return ret;
        ret = regmap_write(ak8974->map, AK8974_CTRL3, 0);
        if (ret)
                return ret;
        if (ak8974->variant == AK8974_WHOAMI_VALUE_AMI306) {
                /* magic from datasheet: set high-speed measurement mode */
                ret = ak8974_set_u16_val(ak8974, AMI306_CTRL4, 0xA07E);
                if (ret)
                        return ret;
        }
        if (ak8974->variant == AK8974_WHOAMI_VALUE_HSCDTD008A)
                return 0;
        ret = regmap_write(ak8974->map, AK8974_INT_CTRL, AK8974_INT_CTRL_POL);
        if (ret)
                return ret;

        return regmap_write(ak8974->map, AK8974_PRESET, 0);
}

static int ak8974_trigmeas(struct ak8974 *ak8974)
{
        unsigned int clear;
        u8 mask;
        u8 val;
        int ret;

        /* Clear any previous measurement overflow status */
        ret = regmap_read(ak8974->map, AK8974_INT_CLEAR, &clear);
        if (ret)
                return ret;

        /* If we have a DRDY IRQ line, use it */
        if (ak8974->drdy_irq) {
                mask = AK8974_CTRL2_INT_EN |
                        AK8974_CTRL2_DRDY_EN |
                        AK8974_CTRL2_DRDY_POL;
                val = AK8974_CTRL2_DRDY_EN;

                if (!ak8974->drdy_active_low)
                        val |= AK8974_CTRL2_DRDY_POL;

                init_completion(&ak8974->drdy_complete);
                ret = regmap_update_bits(ak8974->map, AK8974_CTRL2,
                                         mask, val);
                if (ret)
                        return ret;
        }

        /* Force a measurement */
        return regmap_set_bits(ak8974->map, AK8974_CTRL3, AK8974_CTRL3_FORCE);
}

static int ak8974_await_drdy(struct ak8974 *ak8974)
{
        int timeout = 2;
        unsigned int val;
        int ret;

        if (ak8974->drdy_irq) {
                ret = wait_for_completion_timeout(&ak8974->drdy_complete,
                                        1 + msecs_to_jiffies(1000));
                if (!ret) {
                        dev_err(&ak8974->i2c->dev,
                                "timeout waiting for DRDY IRQ\n");
                        return -ETIMEDOUT;
                }
                return 0;
        }

        /* Default delay-based poll loop */
        do {
                msleep(AK8974_MEASTIME);
                ret = regmap_read(ak8974->map, AK8974_STATUS, &val);
                if (ret < 0)
                        return ret;
                if (val & AK8974_STATUS_DRDY)
                        return 0;
        } while (--timeout);

        dev_err(&ak8974->i2c->dev, "timeout waiting for DRDY\n");
        return -ETIMEDOUT;
}

static int ak8974_getresult(struct ak8974 *ak8974, __le16 *result)
{
        unsigned int src;
        int ret;

        ret = ak8974_await_drdy(ak8974);
        if (ret)
                return ret;
        ret = regmap_read(ak8974->map, AK8974_INT_SRC, &src);
        if (ret < 0)
                return ret;

        /* Out of range overflow! Strong magnet close? */
        if (src & AK8974_INT_RANGE) {
                dev_err(&ak8974->i2c->dev,
                        "range overflow in sensor\n");
                return -ERANGE;
        }

        ret = regmap_bulk_read(ak8974->map, AK8974_DATA_X, result, 6);
        if (ret)
                return ret;

        return ret;
}

static irqreturn_t ak8974_drdy_irq(int irq, void *d)
{
        struct ak8974 *ak8974 = d;

        if (!ak8974->drdy_irq)
                return IRQ_NONE;

        /* TODO: timestamp here to get good measurement stamps */
        return IRQ_WAKE_THREAD;
}

static irqreturn_t ak8974_drdy_irq_thread(int irq, void *d)
{
        struct ak8974 *ak8974 = d;
        unsigned int val;
        int ret;

        /* Check if this was a DRDY from us */
        ret = regmap_read(ak8974->map, AK8974_STATUS, &val);
        if (ret < 0) {
                dev_err(&ak8974->i2c->dev, "error reading DRDY status\n");
                return IRQ_HANDLED;
        }
        if (val & AK8974_STATUS_DRDY) {
                /* Yes this was our IRQ */
                complete(&ak8974->drdy_complete);
                return IRQ_HANDLED;
        }

        /* We may be on a shared IRQ, let the next client check */
        return IRQ_NONE;
}

static int ak8974_selftest(struct ak8974 *ak8974)
{
        struct device *dev = &ak8974->i2c->dev;
        unsigned int val;
        int ret;

        ret = regmap_read(ak8974->map, AK8974_SELFTEST, &val);
        if (ret)
                return ret;
        if (val != AK8974_SELFTEST_IDLE) {
                dev_err(dev, "selftest not idle before test\n");
                return -EIO;
        }

        /* Trigger self-test */
        ret = regmap_set_bits(ak8974->map, AK8974_CTRL3, AK8974_CTRL3_SELFTEST);
        if (ret) {
                dev_err(dev, "could not write CTRL3\n");
                return ret;
        }

        msleep(AK8974_SELFTEST_DELAY);

        ret = regmap_read(ak8974->map, AK8974_SELFTEST, &val);
        if (ret)
                return ret;
        if (val != AK8974_SELFTEST_OK) {
                dev_err(dev, "selftest result NOT OK (%02x)\n", val);
                return -EIO;
        }

        ret = regmap_read(ak8974->map, AK8974_SELFTEST, &val);
        if (ret)
                return ret;
        if (val != AK8974_SELFTEST_IDLE) {
                dev_err(dev, "selftest not idle after test (%02x)\n", val);
                return -EIO;
        }
        dev_dbg(dev, "passed self-test\n");

        return 0;
}

static void ak8974_read_calib_data(struct ak8974 *ak8974, unsigned int reg,
                                   __le16 *tab, size_t tab_size)
{
        int ret = regmap_bulk_read(ak8974->map, reg, tab, tab_size);
        if (ret) {
                memset(tab, 0xFF, tab_size);
                dev_warn(&ak8974->i2c->dev,
                         "can't read calibration data (regs %u..%zu): %d\n",
                         reg, reg + tab_size - 1, ret);
        } else {
                add_device_randomness(tab, tab_size);
        }
}

static int ak8974_detect(struct ak8974 *ak8974)
{
        unsigned int whoami;
        const char *name;
        int ret;
        unsigned int fw;
        u16 sn;

        ret = regmap_read(ak8974->map, AK8974_WHOAMI, &whoami);
        if (ret)
                return ret;

        name = "ami305";

        switch (whoami) {
        case AK8974_WHOAMI_VALUE_AMI306:
                name = "ami306";
                fallthrough;
        case AK8974_WHOAMI_VALUE_AMI305:
                ret = regmap_read(ak8974->map, AMI305_VER, &fw);
                if (ret)
                        return ret;
                fw &= 0x7f; /* only bits 0 thru 6 valid */
                ret = ak8974_get_u16_val(ak8974, AMI305_SN, &sn);
                if (ret)
                        return ret;
                add_device_randomness(&sn, sizeof(sn));
                dev_info(&ak8974->i2c->dev,
                         "detected %s, FW ver %02x, S/N: %04x\n",
                         name, fw, sn);
                break;
        case AK8974_WHOAMI_VALUE_AK8974:
                name = "ak8974";
                dev_info(&ak8974->i2c->dev, "detected AK8974\n");
                break;
        case AK8974_WHOAMI_VALUE_HSCDTD008A:
                name = "hscdtd008a";
                dev_info(&ak8974->i2c->dev, "detected hscdtd008a\n");
                break;
        default:
                dev_err(&ak8974->i2c->dev, "unsupported device (%02x) ",
                        whoami);
                return -ENODEV;
        }

        ak8974->name = name;
        ak8974->variant = whoami;

        if (whoami == AK8974_WHOAMI_VALUE_AMI306) {
                __le16 fab_data1[9], fab_data2[3];
                int i;

                ak8974_read_calib_data(ak8974, AMI306_FINEOUTPUT_X,
                                       fab_data1, sizeof(fab_data1));
                ak8974_read_calib_data(ak8974, AMI306_OFFZERO_X,
                                       fab_data2, sizeof(fab_data2));

                for (i = 0; i < 3; ++i) {
                        static const char axis[] = "XYZ";
                        static const char pgaxis[] = "ZYZXYX";
                        unsigned offz = le16_to_cpu(fab_data2[i]) & 0x7F;
                        unsigned fine = le16_to_cpu(fab_data1[i]);
                        unsigned sens = le16_to_cpu(fab_data1[i + 3]);
                        unsigned pgain1 = le16_to_cpu(fab_data1[i + 6]);
                        unsigned pgain2 = pgain1 >> 8;

                        pgain1 &= 0xFF;

                        dev_info(&ak8974->i2c->dev,
                                 "factory calibration for axis %c: offz=%u sens=%u fine=%u pga%c=%u pga%c=%u\n",
                                 axis[i], offz, sens, fine, pgaxis[i * 2],
                                 pgain1, pgaxis[i * 2 + 1], pgain2);
                }
        }

        return 0;
}

static int ak8974_measure_channel(struct ak8974 *ak8974, unsigned long address,
                                  int *val)
{
        __le16 hw_values[3];
        int ret;

        pm_runtime_get_sync(&ak8974->i2c->dev);
        mutex_lock(&ak8974->lock);

        /*
         * We read all axes and discard all but one, for optimized
         * reading, use the triggered buffer.
         */
        ret = ak8974_trigmeas(ak8974);
        if (ret)
                goto out_unlock;
        ret = ak8974_getresult(ak8974, hw_values);
        if (ret)
                goto out_unlock;
        /*
         * This explicit cast to (s16) is necessary as the measurement
         * is done in 2's complement with positive and negative values.
         * The follwing assignment to *val will then convert the signed
         * s16 value to a signed int value.
         */
        *val = (s16)le16_to_cpu(hw_values[address]);
out_unlock:
        mutex_unlock(&ak8974->lock);
        pm_runtime_put_autosuspend(&ak8974->i2c->dev);

        return ret;
}

static int ak8974_read_raw(struct iio_dev *indio_dev,
                           struct iio_chan_spec const *chan,
                           int *val, int *val2,
                           long mask)
{
        struct ak8974 *ak8974 = iio_priv(indio_dev);
        int ret;

        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                if (chan->address > 2) {
                        dev_err(&ak8974->i2c->dev, "faulty channel address\n");
                        return -EIO;
                }
                ret = ak8974_measure_channel(ak8974, chan->address, val);
                if (ret)
                        return ret;
                return IIO_VAL_INT;
        case IIO_CHAN_INFO_SCALE:
                switch (ak8974->variant) {
                case AK8974_WHOAMI_VALUE_AMI306:
                case AK8974_WHOAMI_VALUE_AMI305:
                        /*
                         * The datasheet for AMI305 and AMI306, page 6
                         * specifies the range of the sensor to be
                         * +/- 12 Gauss.
                         */
                        *val = 12;
                        /*
                         * 12 bits are used, +/- 2^11
                         * [ -2048 .. 2047 ] (manual page 20)
                         * [ 0xf800 .. 0x07ff ]
                         */
                        *val2 = 11;
                        return IIO_VAL_FRACTIONAL_LOG2;
                case AK8974_WHOAMI_VALUE_HSCDTD008A:
                        /*
                         * The datasheet for HSCDTF008A, page 3 specifies the
                         * range of the sensor as +/- 2.4 mT per axis, which
                         * corresponds to +/- 2400 uT = +/- 24 Gauss.
                         */
                        *val = 24;
                        /*
                         * 15 bits are used (set up in CTRL4), +/- 2^14
                         * [ -16384 .. 16383 ] (manual page 24)
                         * [ 0xc000 .. 0x3fff ]
                         */
                        *val2 = 14;
                        return IIO_VAL_FRACTIONAL_LOG2;
                default:
                        /* GUESSING +/- 12 Gauss */
                        *val = 12;
                        /* GUESSING 12 bits ADC +/- 2^11 */
                        *val2 = 11;
                        return IIO_VAL_FRACTIONAL_LOG2;
                }
                break;
        default:
                /* Unknown request */
                break;
        }

        return -EINVAL;
}

static void ak8974_fill_buffer(struct iio_dev *indio_dev)
{
        struct ak8974 *ak8974 = iio_priv(indio_dev);
        int ret;

        pm_runtime_get_sync(&ak8974->i2c->dev);
        mutex_lock(&ak8974->lock);

        ret = ak8974_trigmeas(ak8974);
        if (ret) {
                dev_err(&ak8974->i2c->dev, "error triggering measure\n");
                goto out_unlock;
        }
        ret = ak8974_getresult(ak8974, ak8974->scan.channels);
        if (ret) {
                dev_err(&ak8974->i2c->dev, "error getting measures\n");
                goto out_unlock;
        }

        iio_push_to_buffers_with_ts(indio_dev, &ak8974->scan, sizeof(ak8974->scan),
                                    iio_get_time_ns(indio_dev));

 out_unlock:
        mutex_unlock(&ak8974->lock);
        pm_runtime_put_autosuspend(&ak8974->i2c->dev);
}

static irqreturn_t ak8974_handle_trigger(int irq, void *p)
{
        const struct iio_poll_func *pf = p;
        struct iio_dev *indio_dev = pf->indio_dev;

        ak8974_fill_buffer(indio_dev);
        iio_trigger_notify_done(indio_dev->trig);

        return IRQ_HANDLED;
}

static const struct iio_mount_matrix *
ak8974_get_mount_matrix(const struct iio_dev *indio_dev,
                        const struct iio_chan_spec *chan)
{
        struct ak8974 *ak8974 = iio_priv(indio_dev);

        return &ak8974->orientation;
}

static const struct iio_chan_spec_ext_info ak8974_ext_info[] = {
        IIO_MOUNT_MATRIX(IIO_SHARED_BY_DIR, ak8974_get_mount_matrix),
        { }
};

#define AK8974_AXIS_CHANNEL(axis, index, bits)                          \
        {                                                               \
                .type = IIO_MAGN,                                       \
                .modified = 1,                                          \
                .channel2 = IIO_MOD_##axis,                             \
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |          \
                        BIT(IIO_CHAN_INFO_SCALE),                       \
                .ext_info = ak8974_ext_info,                            \
                .address = index,                                       \
                .scan_index = index,                                    \
                .scan_type = {                                          \
                        .sign = 's',                                    \
                        .realbits = bits,                               \
                        .storagebits = 16,                              \
                        .endianness = IIO_LE                            \
                },                                                      \
        }

/*
 * We have no datasheet for the AK8974 but we guess that its
 * ADC is 12 bits. The AMI305 and AMI306 certainly has 12bit
 * ADC.
 */
static const struct iio_chan_spec ak8974_12_bits_channels[] = {
        AK8974_AXIS_CHANNEL(X, 0, 12),
        AK8974_AXIS_CHANNEL(Y, 1, 12),
        AK8974_AXIS_CHANNEL(Z, 2, 12),
        IIO_CHAN_SOFT_TIMESTAMP(3),
};

/*
 * The HSCDTD008A has 15 bits resolution the way we set it up
 * in CTRL4.
 */
static const struct iio_chan_spec ak8974_15_bits_channels[] = {
        AK8974_AXIS_CHANNEL(X, 0, 15),
        AK8974_AXIS_CHANNEL(Y, 1, 15),
        AK8974_AXIS_CHANNEL(Z, 2, 15),
        IIO_CHAN_SOFT_TIMESTAMP(3),
};

static const unsigned long ak8974_scan_masks[] = { 0x7, 0 };

static const struct iio_info ak8974_info = {
        .read_raw = &ak8974_read_raw,
};

static bool ak8974_writeable_reg(struct device *dev, unsigned int reg)
{
        struct i2c_client *i2c = to_i2c_client(dev);
        struct iio_dev *indio_dev = i2c_get_clientdata(i2c);
        struct ak8974 *ak8974 = iio_priv(indio_dev);

        switch (reg) {
        case AK8974_CTRL1:
        case AK8974_CTRL2:
        case AK8974_CTRL3:
        case AK8974_INT_CTRL:
        case AK8974_INT_THRES:
        case AK8974_INT_THRES + 1:
                return true;
        case AK8974_PRESET:
        case AK8974_PRESET + 1:
                return ak8974->variant != AK8974_WHOAMI_VALUE_HSCDTD008A;
        case AK8974_OFFSET_X:
        case AK8974_OFFSET_X + 1:
        case AK8974_OFFSET_Y:
        case AK8974_OFFSET_Y + 1:
        case AK8974_OFFSET_Z:
        case AK8974_OFFSET_Z + 1:
                return ak8974->variant == AK8974_WHOAMI_VALUE_AK8974 ||
                       ak8974->variant == AK8974_WHOAMI_VALUE_HSCDTD008A;
        case AMI305_OFFSET_X:
        case AMI305_OFFSET_X + 1:
        case AMI305_OFFSET_Y:
        case AMI305_OFFSET_Y + 1:
        case AMI305_OFFSET_Z:
        case AMI305_OFFSET_Z + 1:
                return ak8974->variant == AK8974_WHOAMI_VALUE_AMI305 ||
                       ak8974->variant == AK8974_WHOAMI_VALUE_AMI306;
        case AMI306_CTRL4:
        case AMI306_CTRL4 + 1:
                return ak8974->variant == AK8974_WHOAMI_VALUE_AMI306;
        default:
                return false;
        }
}

static bool ak8974_precious_reg(struct device *dev, unsigned int reg)
{
        return reg == AK8974_INT_CLEAR;
}

static const struct regmap_config ak8974_regmap_config = {
        .reg_bits = 8,
        .val_bits = 8,
        .max_register = 0xff,
        .writeable_reg = ak8974_writeable_reg,
        .precious_reg = ak8974_precious_reg,
};

static int ak8974_probe(struct i2c_client *i2c)
{
        struct iio_dev *indio_dev;
        struct ak8974 *ak8974;
        unsigned long irq_trig;
        int irq = i2c->irq;
        int ret;

        /* Register with IIO */
        indio_dev = devm_iio_device_alloc(&i2c->dev, sizeof(*ak8974));
        if (indio_dev == NULL)
                return -ENOMEM;

        ak8974 = iio_priv(indio_dev);
        i2c_set_clientdata(i2c, indio_dev);
        ak8974->i2c = i2c;
        mutex_init(&ak8974->lock);

        ret = iio_read_mount_matrix(&i2c->dev, &ak8974->orientation);
        if (ret)
                return ret;

        ak8974->regs[0].supply = ak8974_reg_avdd;
        ak8974->regs[1].supply = ak8974_reg_dvdd;

        ret = devm_regulator_bulk_get(&i2c->dev,
                                      ARRAY_SIZE(ak8974->regs),
                                      ak8974->regs);
        if (ret < 0)
                return dev_err_probe(&i2c->dev, ret, "cannot get regulators\n");

        ret = regulator_bulk_enable(ARRAY_SIZE(ak8974->regs), ak8974->regs);
        if (ret < 0) {
                dev_err(&i2c->dev, "cannot enable regulators\n");
                return ret;
        }

        /* Take runtime PM online */
        pm_runtime_get_noresume(&i2c->dev);
        pm_runtime_set_active(&i2c->dev);
        pm_runtime_enable(&i2c->dev);

        ak8974->map = devm_regmap_init_i2c(i2c, &ak8974_regmap_config);
        if (IS_ERR(ak8974->map)) {
                dev_err(&i2c->dev, "failed to allocate register map\n");
                pm_runtime_put_noidle(&i2c->dev);
                pm_runtime_disable(&i2c->dev);
                return PTR_ERR(ak8974->map);
        }

        ret = ak8974_set_power(ak8974, AK8974_PWR_ON);
        if (ret) {
                dev_err(&i2c->dev, "could not power on\n");
                goto disable_pm;
        }

        ret = ak8974_detect(ak8974);
        if (ret) {
                dev_err(&i2c->dev, "neither AK8974 nor AMI30x found\n");
                goto disable_pm;
        }

        ret = ak8974_selftest(ak8974);
        if (ret)
                dev_err(&i2c->dev, "selftest failed (continuing anyway)\n");

        ret = ak8974_reset(ak8974);
        if (ret) {
                dev_err(&i2c->dev, "AK8974 reset failed\n");
                goto disable_pm;
        }

        switch (ak8974->variant) {
        case AK8974_WHOAMI_VALUE_AMI306:
        case AK8974_WHOAMI_VALUE_AMI305:
                indio_dev->channels = ak8974_12_bits_channels;
                indio_dev->num_channels = ARRAY_SIZE(ak8974_12_bits_channels);
                break;
        case AK8974_WHOAMI_VALUE_HSCDTD008A:
                indio_dev->channels = ak8974_15_bits_channels;
                indio_dev->num_channels = ARRAY_SIZE(ak8974_15_bits_channels);
                break;
        default:
                indio_dev->channels = ak8974_12_bits_channels;
                indio_dev->num_channels = ARRAY_SIZE(ak8974_12_bits_channels);
                break;
        }
        indio_dev->info = &ak8974_info;
        indio_dev->available_scan_masks = ak8974_scan_masks;
        indio_dev->modes = INDIO_DIRECT_MODE;
        indio_dev->name = ak8974->name;

        ret = iio_triggered_buffer_setup(indio_dev, NULL,
                                         ak8974_handle_trigger,
                                         NULL);
        if (ret) {
                dev_err(&i2c->dev, "triggered buffer setup failed\n");
                goto disable_pm;
        }

        /* If we have a valid DRDY IRQ, make use of it */
        if (irq > 0) {
                irq_trig = irq_get_trigger_type(irq);
                if (irq_trig == IRQF_TRIGGER_RISING) {
                        dev_info(&i2c->dev, "enable rising edge DRDY IRQ\n");
                } else if (irq_trig == IRQF_TRIGGER_FALLING) {
                        ak8974->drdy_active_low = true;
                        dev_info(&i2c->dev, "enable falling edge DRDY IRQ\n");
                } else {
                        irq_trig = IRQF_TRIGGER_RISING;
                }
                irq_trig |= IRQF_ONESHOT;
                irq_trig |= IRQF_SHARED;

                ret = devm_request_threaded_irq(&i2c->dev,
                                                irq,
                                                ak8974_drdy_irq,
                                                ak8974_drdy_irq_thread,
                                                irq_trig,
                                                ak8974->name,
                                                ak8974);
                if (ret) {
                        dev_err(&i2c->dev, "unable to request DRDY IRQ "
                                "- proceeding without IRQ\n");
                        goto no_irq;
                }
                ak8974->drdy_irq = true;
        }

no_irq:
        ret = iio_device_register(indio_dev);
        if (ret) {
                dev_err(&i2c->dev, "device register failed\n");
                goto cleanup_buffer;
        }

        pm_runtime_set_autosuspend_delay(&i2c->dev,
                                         AK8974_AUTOSUSPEND_DELAY);
        pm_runtime_use_autosuspend(&i2c->dev);
        pm_runtime_put(&i2c->dev);

        return 0;

cleanup_buffer:
        iio_triggered_buffer_cleanup(indio_dev);
disable_pm:
        pm_runtime_put_noidle(&i2c->dev);
        pm_runtime_disable(&i2c->dev);
        ak8974_set_power(ak8974, AK8974_PWR_OFF);
        regulator_bulk_disable(ARRAY_SIZE(ak8974->regs), ak8974->regs);

        return ret;
}

static void ak8974_remove(struct i2c_client *i2c)
{
        struct iio_dev *indio_dev = i2c_get_clientdata(i2c);
        struct ak8974 *ak8974 = iio_priv(indio_dev);

        iio_device_unregister(indio_dev);
        iio_triggered_buffer_cleanup(indio_dev);
        pm_runtime_get_sync(&i2c->dev);
        pm_runtime_put_noidle(&i2c->dev);
        pm_runtime_disable(&i2c->dev);
        ak8974_set_power(ak8974, AK8974_PWR_OFF);
        regulator_bulk_disable(ARRAY_SIZE(ak8974->regs), ak8974->regs);
}

static int ak8974_runtime_suspend(struct device *dev)
{
        struct ak8974 *ak8974 =
                iio_priv(i2c_get_clientdata(to_i2c_client(dev)));

        ak8974_set_power(ak8974, AK8974_PWR_OFF);
        regulator_bulk_disable(ARRAY_SIZE(ak8974->regs), ak8974->regs);

        return 0;
}

static int ak8974_runtime_resume(struct device *dev)
{
        struct ak8974 *ak8974 =
                iio_priv(i2c_get_clientdata(to_i2c_client(dev)));
        int ret;

        ret = regulator_bulk_enable(ARRAY_SIZE(ak8974->regs), ak8974->regs);
        if (ret)
                return ret;
        msleep(AK8974_POWERON_DELAY);
        ret = ak8974_set_power(ak8974, AK8974_PWR_ON);
        if (ret)
                goto out_regulator_disable;

        ret = ak8974_configure(ak8974);
        if (ret)
                goto out_disable_power;

        return 0;

out_disable_power:
        ak8974_set_power(ak8974, AK8974_PWR_OFF);
out_regulator_disable:
        regulator_bulk_disable(ARRAY_SIZE(ak8974->regs), ak8974->regs);

        return ret;
}

static DEFINE_RUNTIME_DEV_PM_OPS(ak8974_dev_pm_ops, ak8974_runtime_suspend,
                                 ak8974_runtime_resume, NULL);

static const struct i2c_device_id ak8974_id[] = {
        { "ami305" },
        { "ami306" },
        { "ak8974" },
        { "hscdtd008a" },
        { }
};
MODULE_DEVICE_TABLE(i2c, ak8974_id);

static const struct of_device_id ak8974_of_match[] = {
        { .compatible = "asahi-kasei,ak8974", },
        { .compatible = "alps,hscdtd008a", },
        { }
};
MODULE_DEVICE_TABLE(of, ak8974_of_match);

static struct i2c_driver ak8974_driver = {
        .driver  = {
                .name   = "ak8974",
                .pm = pm_ptr(&ak8974_dev_pm_ops),
                .of_match_table = ak8974_of_match,
        },
        .probe = ak8974_probe,
        .remove   = ak8974_remove,
        .id_table = ak8974_id,
};
module_i2c_driver(ak8974_driver);

MODULE_DESCRIPTION("AK8974 and AMI30x 3-axis magnetometer driver");
MODULE_AUTHOR("Samu Onkalo");
MODULE_AUTHOR("Linus Walleij");
MODULE_LICENSE("GPL v2");