// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * A sensor driver for the magnetometer AK8975.
 *
 * Magnetic compass sensor driver for monitoring magnetic flux information.
 *
 * Copyright (c) 2010, NVIDIA Corporation.
 */

#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/err.h>
#include <linux/mutex.h>
#include <linux/delay.h>
#include <linux/bitops.h>
#include <linux/gpio/consumer.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>

/*
 * Register definitions, as well as various shifts and masks to get at the
 * individual fields of the registers.
 */
#define AK8975_REG_WIA                  0x00
#define AK8975_DEVICE_ID                0x48

#define AK8975_REG_INFO                 0x01

#define AK8975_REG_ST1                  0x02
#define AK8975_REG_ST1_DRDY_SHIFT       0
#define AK8975_REG_ST1_DRDY_MASK        (1 << AK8975_REG_ST1_DRDY_SHIFT)

#define AK8975_REG_HXL                  0x03
#define AK8975_REG_HXH                  0x04
#define AK8975_REG_HYL                  0x05
#define AK8975_REG_HYH                  0x06
#define AK8975_REG_HZL                  0x07
#define AK8975_REG_HZH                  0x08
#define AK8975_REG_ST2                  0x09
#define AK8975_REG_ST2_DERR_SHIFT       2
#define AK8975_REG_ST2_DERR_MASK        (1 << AK8975_REG_ST2_DERR_SHIFT)

#define AK8975_REG_ST2_HOFL_SHIFT       3
#define AK8975_REG_ST2_HOFL_MASK        (1 << AK8975_REG_ST2_HOFL_SHIFT)

#define AK8975_REG_CNTL                 0x0A
#define AK8975_REG_CNTL_MODE_SHIFT      0
#define AK8975_REG_CNTL_MODE_MASK       (0xF << AK8975_REG_CNTL_MODE_SHIFT)
#define AK8975_REG_CNTL_MODE_POWER_DOWN 0x00
#define AK8975_REG_CNTL_MODE_ONCE       0x01
#define AK8975_REG_CNTL_MODE_SELF_TEST  0x08
#define AK8975_REG_CNTL_MODE_FUSE_ROM   0x0F

#define AK8975_REG_RSVC                 0x0B
#define AK8975_REG_ASTC                 0x0C
#define AK8975_REG_TS1                  0x0D
#define AK8975_REG_TS2                  0x0E
#define AK8975_REG_I2CDIS               0x0F
#define AK8975_REG_ASAX                 0x10
#define AK8975_REG_ASAY                 0x11
#define AK8975_REG_ASAZ                 0x12

#define AK8975_MAX_REGS                 AK8975_REG_ASAZ

/*
 * AK09912 Register definitions
 */
#define AK09912_REG_WIA1                0x00
#define AK09912_REG_WIA2                0x01
#define AK09918_DEVICE_ID               0x0C
#define AK09916_DEVICE_ID               0x09
#define AK09912_DEVICE_ID               0x04
#define AK09911_DEVICE_ID               0x05

#define AK09911_REG_INFO1               0x02
#define AK09911_REG_INFO2               0x03

#define AK09912_REG_ST1                 0x10

#define AK09912_REG_ST1_DRDY_SHIFT      0
#define AK09912_REG_ST1_DRDY_MASK       (1 << AK09912_REG_ST1_DRDY_SHIFT)

#define AK09912_REG_HXL                 0x11
#define AK09912_REG_HXH                 0x12
#define AK09912_REG_HYL                 0x13
#define AK09912_REG_HYH                 0x14
#define AK09912_REG_HZL                 0x15
#define AK09912_REG_HZH                 0x16
#define AK09912_REG_TMPS                0x17

#define AK09912_REG_ST2                 0x18
#define AK09912_REG_ST2_HOFL_SHIFT      3
#define AK09912_REG_ST2_HOFL_MASK       (1 << AK09912_REG_ST2_HOFL_SHIFT)

#define AK09912_REG_CNTL1               0x30

#define AK09912_REG_CNTL2               0x31
#define AK09912_REG_CNTL_MODE_POWER_DOWN        0x00
#define AK09912_REG_CNTL_MODE_ONCE      0x01
#define AK09912_REG_CNTL_MODE_SELF_TEST 0x10
#define AK09912_REG_CNTL_MODE_FUSE_ROM  0x1F
#define AK09912_REG_CNTL2_MODE_SHIFT    0
#define AK09912_REG_CNTL2_MODE_MASK     (0x1F << AK09912_REG_CNTL2_MODE_SHIFT)

#define AK09912_REG_CNTL3               0x32

#define AK09912_REG_TS1                 0x33
#define AK09912_REG_TS2                 0x34
#define AK09912_REG_TS3                 0x35
#define AK09912_REG_I2CDIS              0x36
#define AK09912_REG_TS4                 0x37

#define AK09912_REG_ASAX                0x60
#define AK09912_REG_ASAY                0x61
#define AK09912_REG_ASAZ                0x62

#define AK09912_MAX_REGS                AK09912_REG_ASAZ

/*
 * Miscellaneous values.
 */
#define AK8975_MAX_CONVERSION_TIMEOUT   500
#define AK8975_CONVERSION_DONE_POLL_TIME 10
#define AK8975_DATA_READY_TIMEOUT       ((100*HZ)/1000)

/*
 * Precalculate scale factor (in Gauss units) for each axis and
 * store in the device data.
 *
 * This scale factor is axis-dependent, and is derived from 3 calibration
 * factors ASA(x), ASA(y), and ASA(z).
 *
 * These ASA values are read from the sensor device at start of day, and
 * cached in the device context struct.
 *
 * Adjusting the flux value with the sensitivity adjustment value should be
 * done via the following formula:
 *
 * Hadj = H * ( ( ( (ASA-128)*0.5 ) / 128 ) + 1 )
 * where H is the raw value, ASA is the sensitivity adjustment, and Hadj
 * is the resultant adjusted value.
 *
 * We reduce the formula to:
 *
 * Hadj = H * (ASA + 128) / 256
 *
 * H is in the range of -4096 to 4095.  The magnetometer has a range of
 * +-1229uT.  To go from the raw value to uT is:
 *
 * HuT = H * 1229/4096, or roughly, 3/10.
 *
 * Since 1uT = 0.01 gauss, our final scale factor becomes:
 *
 * Hadj = H * ((ASA + 128) / 256) * 3/10 * 1/100
 * Hadj = H * ((ASA + 128) * 0.003) / 256
 *
 * Since ASA doesn't change, we cache the resultant scale factor into the
 * device context in ak8975_setup().
 *
 * Given we use IIO_VAL_INT_PLUS_MICRO bit when displaying the scale, we
 * multiply the stored scale value by 1e6.
 */
static long ak8975_raw_to_gauss(u16 data)
{
        return (((long)data + 128) * 3000) / 256;
}

/*
 * For AK8963 and AK09911, same calculation, but the device is less sensitive:
 *
 * H is in the range of +-8190.  The magnetometer has a range of
 * +-4912uT.  To go from the raw value to uT is:
 *
 * HuT = H * 4912/8190, or roughly, 6/10, instead of 3/10.
 */

static long ak8963_09911_raw_to_gauss(u16 data)
{
        return (((long)data + 128) * 6000) / 256;
}

/*
 * For AK09912, same calculation, except the device is more sensitive:
 *
 * H is in the range of -32752 to 32752.  The magnetometer has a range of
 * +-4912uT.  To go from the raw value to uT is:
 *
 * HuT = H * 4912/32752, or roughly, 3/20, instead of 3/10.
 */
static long ak09912_raw_to_gauss(u16 data)
{
        return (((long)data + 128) * 1500) / 256;
}

/* Compatible Asahi Kasei Compass parts */
enum asahi_compass_chipset {
        AK8975,
        AK8963,
        AK09911,
        AK09912,
        AK09916,
        AK09918,
};

enum ak_ctrl_reg_addr {
        ST1,
        ST2,
        CNTL,
        ASA_BASE,
        MAX_REGS,
        REGS_END,
};

enum ak_ctrl_reg_mask {
        ST1_DRDY,
        ST2_HOFL,
        ST2_DERR,
        CNTL_MODE,
        MASK_END,
};

enum ak_ctrl_mode {
        POWER_DOWN,
        MODE_ONCE,
        SELF_TEST,
        FUSE_ROM,
        MODE_END,
};

struct ak_def {
        enum asahi_compass_chipset type;
        long (*raw_to_gauss)(u16 data);
        u16 range;
        u8 ctrl_regs[REGS_END];
        u8 ctrl_masks[MASK_END];
        u8 ctrl_modes[MODE_END];
        u8 data_regs[3];
};

static const struct ak_def ak_def_array[] = {
        [AK8975] = {
                .type = AK8975,
                .raw_to_gauss = ak8975_raw_to_gauss,
                .range = 4096,
                .ctrl_regs = {
                        AK8975_REG_ST1,
                        AK8975_REG_ST2,
                        AK8975_REG_CNTL,
                        AK8975_REG_ASAX,
                        AK8975_MAX_REGS},
                .ctrl_masks = {
                        AK8975_REG_ST1_DRDY_MASK,
                        AK8975_REG_ST2_HOFL_MASK,
                        AK8975_REG_ST2_DERR_MASK,
                        AK8975_REG_CNTL_MODE_MASK},
                .ctrl_modes = {
                        AK8975_REG_CNTL_MODE_POWER_DOWN,
                        AK8975_REG_CNTL_MODE_ONCE,
                        AK8975_REG_CNTL_MODE_SELF_TEST,
                        AK8975_REG_CNTL_MODE_FUSE_ROM},
                .data_regs = {
                        AK8975_REG_HXL,
                        AK8975_REG_HYL,
                        AK8975_REG_HZL},
        },
        [AK8963] = {
                .type = AK8963,
                .raw_to_gauss = ak8963_09911_raw_to_gauss,
                .range = 8190,
                .ctrl_regs = {
                        AK8975_REG_ST1,
                        AK8975_REG_ST2,
                        AK8975_REG_CNTL,
                        AK8975_REG_ASAX,
                        AK8975_MAX_REGS},
                .ctrl_masks = {
                        AK8975_REG_ST1_DRDY_MASK,
                        AK8975_REG_ST2_HOFL_MASK,
                        0,
                        AK8975_REG_CNTL_MODE_MASK},
                .ctrl_modes = {
                        AK8975_REG_CNTL_MODE_POWER_DOWN,
                        AK8975_REG_CNTL_MODE_ONCE,
                        AK8975_REG_CNTL_MODE_SELF_TEST,
                        AK8975_REG_CNTL_MODE_FUSE_ROM},
                .data_regs = {
                        AK8975_REG_HXL,
                        AK8975_REG_HYL,
                        AK8975_REG_HZL},
        },
        [AK09911] = {
                .type = AK09911,
                .raw_to_gauss = ak8963_09911_raw_to_gauss,
                .range = 8192,
                .ctrl_regs = {
                        AK09912_REG_ST1,
                        AK09912_REG_ST2,
                        AK09912_REG_CNTL2,
                        AK09912_REG_ASAX,
                        AK09912_MAX_REGS},
                .ctrl_masks = {
                        AK09912_REG_ST1_DRDY_MASK,
                        AK09912_REG_ST2_HOFL_MASK,
                        0,
                        AK09912_REG_CNTL2_MODE_MASK},
                .ctrl_modes = {
                        AK09912_REG_CNTL_MODE_POWER_DOWN,
                        AK09912_REG_CNTL_MODE_ONCE,
                        AK09912_REG_CNTL_MODE_SELF_TEST,
                        AK09912_REG_CNTL_MODE_FUSE_ROM},
                .data_regs = {
                        AK09912_REG_HXL,
                        AK09912_REG_HYL,
                        AK09912_REG_HZL},
        },
        [AK09912] = {
                .type = AK09912,
                .raw_to_gauss = ak09912_raw_to_gauss,
                .range = 32752,
                .ctrl_regs = {
                        AK09912_REG_ST1,
                        AK09912_REG_ST2,
                        AK09912_REG_CNTL2,
                        AK09912_REG_ASAX,
                        AK09912_MAX_REGS},
                .ctrl_masks = {
                        AK09912_REG_ST1_DRDY_MASK,
                        AK09912_REG_ST2_HOFL_MASK,
                        0,
                        AK09912_REG_CNTL2_MODE_MASK},
                .ctrl_modes = {
                        AK09912_REG_CNTL_MODE_POWER_DOWN,
                        AK09912_REG_CNTL_MODE_ONCE,
                        AK09912_REG_CNTL_MODE_SELF_TEST,
                        AK09912_REG_CNTL_MODE_FUSE_ROM},
                .data_regs = {
                        AK09912_REG_HXL,
                        AK09912_REG_HYL,
                        AK09912_REG_HZL},
        },
        [AK09916] = {
                .type = AK09916,
                .raw_to_gauss = ak09912_raw_to_gauss,
                .range = 32752,
                .ctrl_regs = {
                        AK09912_REG_ST1,
                        AK09912_REG_ST2,
                        AK09912_REG_CNTL2,
                        AK09912_REG_ASAX,
                        AK09912_MAX_REGS},
                .ctrl_masks = {
                        AK09912_REG_ST1_DRDY_MASK,
                        AK09912_REG_ST2_HOFL_MASK,
                        0,
                        AK09912_REG_CNTL2_MODE_MASK},
                .ctrl_modes = {
                        AK09912_REG_CNTL_MODE_POWER_DOWN,
                        AK09912_REG_CNTL_MODE_ONCE,
                        AK09912_REG_CNTL_MODE_SELF_TEST,
                        AK09912_REG_CNTL_MODE_FUSE_ROM},
                .data_regs = {
                        AK09912_REG_HXL,
                        AK09912_REG_HYL,
                        AK09912_REG_HZL},
        },
        [AK09918] = {
                /* ak09918 is register compatible with ak09912 this is for avoid
                 * unknown id messages.
                 */
                .type = AK09918,
                .raw_to_gauss = ak09912_raw_to_gauss,
                .range = 32752,
                .ctrl_regs = {
                        AK09912_REG_ST1,
                        AK09912_REG_ST2,
                        AK09912_REG_CNTL2,
                        AK09912_REG_ASAX,
                        AK09912_MAX_REGS},
                .ctrl_masks = {
                        AK09912_REG_ST1_DRDY_MASK,
                        AK09912_REG_ST2_HOFL_MASK,
                        0,
                        AK09912_REG_CNTL2_MODE_MASK},
                .ctrl_modes = {
                        AK09912_REG_CNTL_MODE_POWER_DOWN,
                        AK09912_REG_CNTL_MODE_ONCE,
                        AK09912_REG_CNTL_MODE_SELF_TEST,
                        AK09912_REG_CNTL_MODE_FUSE_ROM},
                .data_regs = {
                        AK09912_REG_HXL,
                        AK09912_REG_HYL,
                        AK09912_REG_HZL},
        }
};

/*
 * Per-instance context data for the device.
 */
struct ak8975_data {
        struct i2c_client       *client;
        const struct ak_def     *def;
        struct mutex            lock;
        u8                      asa[3];
        long                    raw_to_gauss[3];
        struct gpio_desc        *eoc_gpiod;
        struct gpio_desc        *reset_gpiod;
        int                     eoc_irq;
        wait_queue_head_t       data_ready_queue;
        unsigned long           flags;
        u8                      cntl_cache;
        struct iio_mount_matrix orientation;
        struct regulator        *vdd;
        struct regulator        *vid;

        /* Ensure natural alignment of timestamp */
        struct {
                s16 channels[3];
                aligned_s64 ts;
        } scan;
};

/* Enable attached power regulator if any. */
static int ak8975_power_on(const struct ak8975_data *data)
{
        int ret;

        ret = regulator_enable(data->vdd);
        if (ret) {
                dev_warn(&data->client->dev,
                         "Failed to enable specified Vdd supply\n");
                return ret;
        }
        ret = regulator_enable(data->vid);
        if (ret) {
                dev_warn(&data->client->dev,
                         "Failed to enable specified Vid supply\n");
                regulator_disable(data->vdd);
                return ret;
        }

        gpiod_set_value_cansleep(data->reset_gpiod, 0);

        /*
         * According to the datasheet the power supply rise time is 200us
         * and the minimum wait time before mode setting is 100us, in
         * total 300us. Add some margin and say minimum 500us here.
         */
        usleep_range(500, 1000);
        return 0;
}

/* Disable attached power regulator if any. */
static void ak8975_power_off(const struct ak8975_data *data)
{
        gpiod_set_value_cansleep(data->reset_gpiod, 1);

        regulator_disable(data->vid);
        regulator_disable(data->vdd);
}

/*
 * Return 0 if the i2c device is the one we expect.
 * return a negative error number otherwise
 */
static int ak8975_who_i_am(struct i2c_client *client,
                           enum asahi_compass_chipset type)
{
        u8 wia_val[2];
        int ret;

        /*
         * Signature for each device:
         * Device   |  WIA1      |  WIA2
         * AK09918  |  DEVICE_ID_|  AK09918_DEVICE_ID
         * AK09916  |  DEVICE_ID_|  AK09916_DEVICE_ID
         * AK09912  |  DEVICE_ID |  AK09912_DEVICE_ID
         * AK09911  |  DEVICE_ID |  AK09911_DEVICE_ID
         * AK8975   |  DEVICE_ID |  NA
         * AK8963   |  DEVICE_ID |  NA
         */
        ret = i2c_smbus_read_i2c_block_data_or_emulated(
                        client, AK09912_REG_WIA1, 2, wia_val);
        if (ret < 0) {
                dev_err(&client->dev, "Error reading WIA\n");
                return ret;
        }

        if (wia_val[0] != AK8975_DEVICE_ID)
                return -ENODEV;

        switch (type) {
        case AK8975:
        case AK8963:
                return 0;
        case AK09911:
                if (wia_val[1] == AK09911_DEVICE_ID)
                        return 0;
                break;
        case AK09912:
                if (wia_val[1] == AK09912_DEVICE_ID)
                        return 0;
                break;
        case AK09916:
                if (wia_val[1] == AK09916_DEVICE_ID)
                        return 0;
                break;
        case AK09918:
                if (wia_val[1] == AK09918_DEVICE_ID)
                        return 0;
                break;
        }

        dev_info(&client->dev, "Device ID %x is unknown.\n", wia_val[1]);
        /*
         * Let driver to probe on unknown id for support more register
         * compatible variants.
         */
        return 0;
}

/*
 * Helper function to write to CNTL register.
 */
static int ak8975_set_mode(struct ak8975_data *data, enum ak_ctrl_mode mode)
{
        u8 regval;
        int ret;

        regval = (data->cntl_cache & ~data->def->ctrl_masks[CNTL_MODE]) |
                 data->def->ctrl_modes[mode];
        ret = i2c_smbus_write_byte_data(data->client,
                                        data->def->ctrl_regs[CNTL], regval);
        if (ret < 0) {
                return ret;
        }
        data->cntl_cache = regval;
        /* After mode change wait atleast 100us */
        usleep_range(100, 500);

        return 0;
}

/*
 * Handle data ready irq
 */
static irqreturn_t ak8975_irq_handler(int irq, void *data)
{
        struct ak8975_data *ak8975 = data;

        set_bit(0, &ak8975->flags);
        wake_up(&ak8975->data_ready_queue);

        return IRQ_HANDLED;
}

/*
 * Install data ready interrupt handler
 */
static int ak8975_setup_irq(struct ak8975_data *data)
{
        struct i2c_client *client = data->client;
        int rc;
        int irq;

        init_waitqueue_head(&data->data_ready_queue);
        clear_bit(0, &data->flags);
        if (client->irq)
                irq = client->irq;
        else
                irq = gpiod_to_irq(data->eoc_gpiod);

        rc = devm_request_irq(&client->dev, irq, ak8975_irq_handler,
                              IRQF_TRIGGER_RISING,
                              dev_name(&client->dev), data);
        if (rc < 0) {
                dev_err(&client->dev, "irq %d request failed: %d\n", irq, rc);
                return rc;
        }

        data->eoc_irq = irq;

        return rc;
}


/*
 * Perform some start-of-day setup, including reading the asa calibration
 * values and caching them.
 */
static int ak8975_setup(struct i2c_client *client)
{
        struct iio_dev *indio_dev = i2c_get_clientdata(client);
        struct ak8975_data *data = iio_priv(indio_dev);
        int ret;

        /* Write the fused rom access mode. */
        ret = ak8975_set_mode(data, FUSE_ROM);
        if (ret < 0) {
                dev_err(&client->dev, "Error in setting fuse access mode\n");
                return ret;
        }

        /* Get asa data and store in the device data. */
        ret = i2c_smbus_read_i2c_block_data_or_emulated(
                        client, data->def->ctrl_regs[ASA_BASE],
                        3, data->asa);
        if (ret < 0) {
                dev_err(&client->dev, "Not able to read asa data\n");
                return ret;
        }

        /* After reading fuse ROM data set power-down mode */
        ret = ak8975_set_mode(data, POWER_DOWN);
        if (ret < 0) {
                dev_err(&client->dev, "Error in setting power-down mode\n");
                return ret;
        }

        if (data->eoc_gpiod || client->irq > 0) {
                ret = ak8975_setup_irq(data);
                if (ret < 0) {
                        dev_err(&client->dev,
                                "Error setting data ready interrupt\n");
                        return ret;
                }
        }

        data->raw_to_gauss[0] = data->def->raw_to_gauss(data->asa[0]);
        data->raw_to_gauss[1] = data->def->raw_to_gauss(data->asa[1]);
        data->raw_to_gauss[2] = data->def->raw_to_gauss(data->asa[2]);

        return 0;
}

static int wait_conversion_complete_gpio(struct ak8975_data *data)
{
        struct i2c_client *client = data->client;
        u32 timeout_ms = AK8975_MAX_CONVERSION_TIMEOUT;
        int ret;

        /* Wait for the conversion to complete. */
        while (timeout_ms) {
                msleep(AK8975_CONVERSION_DONE_POLL_TIME);
                if (gpiod_get_value(data->eoc_gpiod))
                        break;
                timeout_ms -= AK8975_CONVERSION_DONE_POLL_TIME;
        }
        if (!timeout_ms) {
                dev_err(&client->dev, "Conversion timeout happened\n");
                return -EINVAL;
        }

        ret = i2c_smbus_read_byte_data(client, data->def->ctrl_regs[ST1]);
        if (ret < 0)
                dev_err(&client->dev, "Error in reading ST1\n");

        return ret;
}

static int wait_conversion_complete_polled(struct ak8975_data *data)
{
        struct i2c_client *client = data->client;
        u8 read_status;
        u32 timeout_ms = AK8975_MAX_CONVERSION_TIMEOUT;
        int ret;

        /* Wait for the conversion to complete. */
        while (timeout_ms) {
                msleep(AK8975_CONVERSION_DONE_POLL_TIME);
                ret = i2c_smbus_read_byte_data(client,
                                               data->def->ctrl_regs[ST1]);
                if (ret < 0) {
                        dev_err(&client->dev, "Error in reading ST1\n");
                        return ret;
                }
                read_status = ret;
                if (read_status)
                        break;
                timeout_ms -= AK8975_CONVERSION_DONE_POLL_TIME;
        }
        if (!timeout_ms) {
                dev_err(&client->dev, "Conversion timeout happened\n");
                return -EINVAL;
        }

        return read_status;
}

/* Returns 0 if the end of conversion interrupt occured or -ETIME otherwise */
static int wait_conversion_complete_interrupt(struct ak8975_data *data)
{
        int ret;

        ret = wait_event_timeout(data->data_ready_queue,
                                 test_bit(0, &data->flags),
                                 AK8975_DATA_READY_TIMEOUT);
        clear_bit(0, &data->flags);

        return ret > 0 ? 0 : -ETIME;
}

static int ak8975_start_read_axis(struct ak8975_data *data,
                                  const struct i2c_client *client)
{
        /* Set up the device for taking a sample. */
        int ret = ak8975_set_mode(data, MODE_ONCE);

        if (ret < 0) {
                dev_err(&client->dev, "Error in setting operating mode\n");
                return ret;
        }

        /* Wait for the conversion to complete. */
        if (data->eoc_irq)
                ret = wait_conversion_complete_interrupt(data);
        else if (data->eoc_gpiod)
                ret = wait_conversion_complete_gpio(data);
        else
                ret = wait_conversion_complete_polled(data);
        if (ret < 0)
                return ret;

        /* Return with zero if the data is ready. */
        return !data->def->ctrl_regs[ST1_DRDY];
}

/* Retrieve raw flux value for one of the x, y, or z axis.  */
static int ak8975_read_axis(struct iio_dev *indio_dev, int index, int *val)
{
        struct ak8975_data *data = iio_priv(indio_dev);
        const struct i2c_client *client = data->client;
        const struct ak_def *def = data->def;
        __le16 rval;
        u16 buff;
        int ret;

        pm_runtime_get_sync(&data->client->dev);

        mutex_lock(&data->lock);

        ret = ak8975_start_read_axis(data, client);
        if (ret)
                goto exit;

        ret = i2c_smbus_read_i2c_block_data_or_emulated(
                        client, def->data_regs[index],
                        sizeof(rval), (u8*)&rval);
        if (ret < 0)
                goto exit;

        /* Read out ST2 for release lock on measurment data. */
        ret = i2c_smbus_read_byte_data(client, data->def->ctrl_regs[ST2]);
        if (ret < 0) {
                dev_err(&client->dev, "Error in reading ST2\n");
                goto exit;
        }

        if (ret & (data->def->ctrl_masks[ST2_DERR] |
                   data->def->ctrl_masks[ST2_HOFL])) {
                dev_err(&client->dev, "ST2 status error 0x%x\n", ret);
                ret = -EINVAL;
                goto exit;
        }

        mutex_unlock(&data->lock);

        pm_runtime_put_autosuspend(&data->client->dev);

        /* Swap bytes and convert to valid range. */
        buff = le16_to_cpu(rval);
        *val = clamp_t(s16, buff, -def->range, def->range);
        return IIO_VAL_INT;

exit:
        mutex_unlock(&data->lock);
        dev_err(&client->dev, "Error in reading axis\n");
        return ret;
}

static int ak8975_read_raw(struct iio_dev *indio_dev,
                           struct iio_chan_spec const *chan,
                           int *val, int *val2,
                           long mask)
{
        struct ak8975_data *data = iio_priv(indio_dev);

        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                return ak8975_read_axis(indio_dev, chan->address, val);
        case IIO_CHAN_INFO_SCALE:
                *val = 0;
                *val2 = data->raw_to_gauss[chan->address];
                return IIO_VAL_INT_PLUS_MICRO;
        }
        return -EINVAL;
}

static const struct iio_mount_matrix *
ak8975_get_mount_matrix(const struct iio_dev *indio_dev,
                        const struct iio_chan_spec *chan)
{
        struct ak8975_data *data = iio_priv(indio_dev);

        return &data->orientation;
}

static const struct iio_chan_spec_ext_info ak8975_ext_info[] = {
        IIO_MOUNT_MATRIX(IIO_SHARED_BY_DIR, ak8975_get_mount_matrix),
        { }
};

#define AK8975_CHANNEL(axis, index)                                     \
        {                                                               \
                .type = IIO_MAGN,                                       \
                .modified = 1,                                          \
                .channel2 = IIO_MOD_##axis,                             \
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |          \
                             BIT(IIO_CHAN_INFO_SCALE),                  \
                .address = index,                                       \
                .scan_index = index,                                    \
                .scan_type = {                                          \
                        .sign = 's',                                    \
                        .realbits = 16,                                 \
                        .storagebits = 16,                              \
                        .endianness = IIO_CPU                           \
                },                                                      \
                .ext_info = ak8975_ext_info,                            \
        }

static const struct iio_chan_spec ak8975_channels[] = {
        AK8975_CHANNEL(X, 0), AK8975_CHANNEL(Y, 1), AK8975_CHANNEL(Z, 2),
        IIO_CHAN_SOFT_TIMESTAMP(3),
};

static const unsigned long ak8975_scan_masks[] = { 0x7, 0 };

static const struct iio_info ak8975_info = {
        .read_raw = &ak8975_read_raw,
};

static void ak8975_fill_buffer(struct iio_dev *indio_dev)
{
        struct ak8975_data *data = iio_priv(indio_dev);
        const struct i2c_client *client = data->client;
        const struct ak_def *def = data->def;
        int ret;
        __le16 fval[3];

        mutex_lock(&data->lock);

        ret = ak8975_start_read_axis(data, client);
        if (ret)
                goto unlock;

        /*
         * For each axis, read the flux value from the appropriate register
         * (the register is specified in the iio device attributes).
         */
        ret = i2c_smbus_read_i2c_block_data_or_emulated(client,
                                                        def->data_regs[0],
                                                        3 * sizeof(fval[0]),
                                                        (u8 *)fval);
        if (ret < 0)
                goto unlock;

        mutex_unlock(&data->lock);

        /* Clamp to valid range. */
        data->scan.channels[0] = clamp_t(s16, le16_to_cpu(fval[0]), -def->range, def->range);
        data->scan.channels[1] = clamp_t(s16, le16_to_cpu(fval[1]), -def->range, def->range);
        data->scan.channels[2] = clamp_t(s16, le16_to_cpu(fval[2]), -def->range, def->range);

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

        return;

unlock:
        mutex_unlock(&data->lock);
        dev_err(&client->dev, "Error in reading axes block\n");
}

static irqreturn_t ak8975_handle_trigger(int irq, void *p)
{
        const struct iio_poll_func *pf = p;
        struct iio_dev *indio_dev = pf->indio_dev;

        ak8975_fill_buffer(indio_dev);
        iio_trigger_notify_done(indio_dev->trig);
        return IRQ_HANDLED;
}

static int ak8975_probe(struct i2c_client *client)
{
        const struct i2c_device_id *id = i2c_client_get_device_id(client);
        struct ak8975_data *data;
        struct iio_dev *indio_dev;
        struct gpio_desc *eoc_gpiod;
        struct gpio_desc *reset_gpiod;
        int err;
        const char *name = NULL;

        /*
         * Grab and set up the supplied GPIO.
         * We may not have a GPIO based IRQ to scan, that is fine, we will
         * poll if so.
         */
        eoc_gpiod = devm_gpiod_get_optional(&client->dev, NULL, GPIOD_IN);
        if (IS_ERR(eoc_gpiod))
                return PTR_ERR(eoc_gpiod);
        if (eoc_gpiod)
                gpiod_set_consumer_name(eoc_gpiod, "ak_8975");

        /*
         * According to AK09911 datasheet, if reset GPIO is provided then
         * deassert reset on ak8975_power_on() and assert reset on
         * ak8975_power_off().
         */
        reset_gpiod = devm_gpiod_get_optional(&client->dev,
                                              "reset", GPIOD_OUT_HIGH);
        if (IS_ERR(reset_gpiod))
                return PTR_ERR(reset_gpiod);

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

        data = iio_priv(indio_dev);
        i2c_set_clientdata(client, indio_dev);

        data->client = client;
        data->eoc_gpiod = eoc_gpiod;
        data->reset_gpiod = reset_gpiod;
        data->eoc_irq = 0;

        err = iio_read_mount_matrix(&client->dev, &data->orientation);
        if (err)
                return err;

        /* id will be NULL when enumerated via ACPI */
        data->def = i2c_get_match_data(client);
        if (!data->def)
                return -ENODEV;

        /* If enumerated via firmware node, fix the ABI */
        if (dev_fwnode(&client->dev))
                name = dev_name(&client->dev);
        else
                name = id->name;

        /* Fetch the regulators */
        data->vdd = devm_regulator_get(&client->dev, "vdd");
        if (IS_ERR(data->vdd))
                return PTR_ERR(data->vdd);
        data->vid = devm_regulator_get(&client->dev, "vid");
        if (IS_ERR(data->vid))
                return PTR_ERR(data->vid);

        err = ak8975_power_on(data);
        if (err)
                return err;

        err = ak8975_who_i_am(client, data->def->type);
        if (err < 0) {
                dev_err(&client->dev, "Unexpected device\n");
                goto power_off;
        }
        dev_dbg(&client->dev, "Asahi compass chip %s\n", name);

        /* Perform some basic start-of-day setup of the device. */
        err = ak8975_setup(client);
        if (err < 0) {
                dev_err(&client->dev, "%s initialization fails\n", name);
                goto power_off;
        }

        mutex_init(&data->lock);
        indio_dev->channels = ak8975_channels;
        indio_dev->num_channels = ARRAY_SIZE(ak8975_channels);
        indio_dev->info = &ak8975_info;
        indio_dev->available_scan_masks = ak8975_scan_masks;
        indio_dev->modes = INDIO_DIRECT_MODE;
        indio_dev->name = name;

        err = iio_triggered_buffer_setup(indio_dev, NULL, ak8975_handle_trigger,
                                         NULL);
        if (err) {
                dev_err(&client->dev, "triggered buffer setup failed\n");
                goto power_off;
        }

        err = iio_device_register(indio_dev);
        if (err) {
                dev_err(&client->dev, "device register failed\n");
                goto cleanup_buffer;
        }

        /* Enable runtime PM */
        pm_runtime_get_noresume(&client->dev);
        pm_runtime_set_active(&client->dev);
        pm_runtime_enable(&client->dev);
        /*
         * The device comes online in 500us, so add two orders of magnitude
         * of delay before autosuspending: 50 ms.
         */
        pm_runtime_set_autosuspend_delay(&client->dev, 50);
        pm_runtime_use_autosuspend(&client->dev);
        pm_runtime_put(&client->dev);

        return 0;

cleanup_buffer:
        iio_triggered_buffer_cleanup(indio_dev);
power_off:
        ak8975_power_off(data);
        return err;
}

static void ak8975_remove(struct i2c_client *client)
{
        struct iio_dev *indio_dev = i2c_get_clientdata(client);
        struct ak8975_data *data = iio_priv(indio_dev);

        pm_runtime_get_sync(&client->dev);
        pm_runtime_put_noidle(&client->dev);
        pm_runtime_disable(&client->dev);
        iio_device_unregister(indio_dev);
        iio_triggered_buffer_cleanup(indio_dev);
        ak8975_set_mode(data, POWER_DOWN);
        ak8975_power_off(data);
}

static int ak8975_runtime_suspend(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct iio_dev *indio_dev = i2c_get_clientdata(client);
        struct ak8975_data *data = iio_priv(indio_dev);
        int ret;

        /* Set the device in power down if it wasn't already */
        ret = ak8975_set_mode(data, POWER_DOWN);
        if (ret < 0) {
                dev_err(&client->dev, "Error in setting power-down mode\n");
                return ret;
        }
        /* Next cut the regulators */
        ak8975_power_off(data);

        return 0;
}

static int ak8975_runtime_resume(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct iio_dev *indio_dev = i2c_get_clientdata(client);
        struct ak8975_data *data = iio_priv(indio_dev);
        int ret;

        /* Take up the regulators */
        ak8975_power_on(data);
        /*
         * We come up in powered down mode, the reading routines will
         * put us in the mode to read values later.
         */
        ret = ak8975_set_mode(data, POWER_DOWN);
        if (ret < 0) {
                dev_err(&client->dev, "Error in setting power-down mode\n");
                return ret;
        }

        return 0;
}

static DEFINE_RUNTIME_DEV_PM_OPS(ak8975_dev_pm_ops, ak8975_runtime_suspend,
                                 ak8975_runtime_resume, NULL);

static const struct acpi_device_id ak_acpi_match[] = {
        {"AK8963", (kernel_ulong_t)&ak_def_array[AK8963] },
        {"AK8975", (kernel_ulong_t)&ak_def_array[AK8975] },
        {"AK009911", (kernel_ulong_t)&ak_def_array[AK09911] },
        {"AK09911", (kernel_ulong_t)&ak_def_array[AK09911] },
        {"AK09912", (kernel_ulong_t)&ak_def_array[AK09912] },
        {"AKM9911", (kernel_ulong_t)&ak_def_array[AK09911] },
        {"INVN6500", (kernel_ulong_t)&ak_def_array[AK8963] },
        { }
};
MODULE_DEVICE_TABLE(acpi, ak_acpi_match);

static const struct i2c_device_id ak8975_id[] = {
        {"AK8963", (kernel_ulong_t)&ak_def_array[AK8963] },
        {"ak8963", (kernel_ulong_t)&ak_def_array[AK8963] },
        {"ak8975", (kernel_ulong_t)&ak_def_array[AK8975] },
        {"ak09911", (kernel_ulong_t)&ak_def_array[AK09911] },
        {"ak09912", (kernel_ulong_t)&ak_def_array[AK09912] },
        {"ak09916", (kernel_ulong_t)&ak_def_array[AK09916] },
        {"ak09918", (kernel_ulong_t)&ak_def_array[AK09918] },
        { }
};
MODULE_DEVICE_TABLE(i2c, ak8975_id);

static const struct of_device_id ak8975_of_match[] = {
        { .compatible = "asahi-kasei,ak8975", .data = &ak_def_array[AK8975] },
        { .compatible = "ak8975", .data = &ak_def_array[AK8975] },
        { .compatible = "asahi-kasei,ak8963", .data = &ak_def_array[AK8963] },
        { .compatible = "ak8963", .data = &ak_def_array[AK8963] },
        { .compatible = "asahi-kasei,ak09911", .data = &ak_def_array[AK09911] },
        { .compatible = "ak09911", .data = &ak_def_array[AK09911] },
        { .compatible = "asahi-kasei,ak09912", .data = &ak_def_array[AK09912] },
        { .compatible = "ak09912", .data = &ak_def_array[AK09912] },
        { .compatible = "asahi-kasei,ak09916", .data = &ak_def_array[AK09916] },
        { .compatible = "asahi-kasei,ak09918", .data = &ak_def_array[AK09918] },
        { }
};
MODULE_DEVICE_TABLE(of, ak8975_of_match);

static struct i2c_driver ak8975_driver = {
        .driver = {
                .name   = "ak8975",
                .pm = pm_ptr(&ak8975_dev_pm_ops),
                .of_match_table = ak8975_of_match,
                .acpi_match_table = ak_acpi_match,
        },
        .probe          = ak8975_probe,
        .remove         = ak8975_remove,
        .id_table       = ak8975_id,
};
module_i2c_driver(ak8975_driver);

MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>");
MODULE_DESCRIPTION("AK8975 magnetometer driver");
MODULE_LICENSE("GPL");