/*
 * A sensor driver for the magnetometer AK8975.
 *
 * Magnetic compass sensor driver for monitoring magnetic flux information.
 *
 * Copyright (c) 2010, NVIDIA Corporation.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */

#include <linux/module.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.h>
#include <linux/of_gpio.h>
#include <linux/acpi.h>

#include <linux/iio/iio.h>
#include <linux/iio/sysfs.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 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,
        AK_MAX_TYPE
};

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[AK_MAX_TYPE] = {
        {
                .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},
        },
        {
                .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},
        },
        {
                .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},
        },
        {
                .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},
        }
};

/*
 * Per-instance context data for the device.
 */
struct ak8975_data {
        struct i2c_client       *client;
        const struct ak_def     *def;
        struct attribute_group  attrs;
        struct mutex            lock;
        u8                      asa[3];
        long                    raw_to_gauss[3];
        int                     eoc_gpio;
        int                     eoc_irq;
        wait_queue_head_t       data_ready_queue;
        unsigned long           flags;
        u8                      cntl_cache;
};

/*
 * 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
         * 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(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;
        default:
                dev_err(&client->dev, "Type %d unknown\n", type);
        }
        return -ENODEV;
}

/*
 * 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 = gpio_to_irq(data->eoc_gpio);

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

/*
 * Emits the raw flux value for 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);
        struct i2c_client *client = data->client;
        int ret;

        mutex_lock(&data->lock);

        /* Set up the device for taking a sample. */
        ret = ak8975_set_mode(data, MODE_ONCE);
        if (ret < 0) {
                dev_err(&client->dev, "Error in setting operating mode\n");
                goto exit;
        }

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

        /* This will be executed only for non-interrupt based waiting case */
        if (ret & data->def->ctrl_masks[ST1_DRDY]) {
                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;
                }
        }

        /* Read the flux value from the appropriate register
           (the register is specified in the iio device attributes). */
        ret = i2c_smbus_read_word_data(client, data->def->data_regs[index]);
        if (ret < 0) {
                dev_err(&client->dev, "Read axis data fails\n");
                goto exit;
        }

        mutex_unlock(&data->lock);

        /* Clamp to valid range. */
        *val = clamp_t(s16, ret, -data->def->range, data->def->range);
        return IIO_VAL_INT;

exit:
        mutex_unlock(&data->lock);
        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;
}

#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,                                       \
        }

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

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

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

static const char *ak8975_match_acpi_device(struct device *dev,
                                            enum asahi_compass_chipset *chipset)
{
        const struct acpi_device_id *id;

        id = acpi_match_device(dev->driver->acpi_match_table, dev);
        if (!id)
                return NULL;
        *chipset = (int)id->driver_data;

        return dev_name(dev);
}

static int ak8975_probe(struct i2c_client *client,
                        const struct i2c_device_id *id)
{
        struct ak8975_data *data;
        struct iio_dev *indio_dev;
        int eoc_gpio;
        int err;
        const char *name = NULL;
        enum asahi_compass_chipset chipset = AK_MAX_TYPE;

        /* Grab and set up the supplied GPIO. */
        if (client->dev.platform_data)
                eoc_gpio = *(int *)(client->dev.platform_data);
        else if (client->dev.of_node)
                eoc_gpio = of_get_gpio(client->dev.of_node, 0);
        else
                eoc_gpio = -1;

        if (eoc_gpio == -EPROBE_DEFER)
                return -EPROBE_DEFER;

        /* We may not have a GPIO based IRQ to scan, that is fine, we will
           poll if so */
        if (gpio_is_valid(eoc_gpio)) {
                err = devm_gpio_request_one(&client->dev, eoc_gpio,
                                                        GPIOF_IN, "ak_8975");
                if (err < 0) {
                        dev_err(&client->dev,
                                "failed to request GPIO %d, error %d\n",
                                                        eoc_gpio, err);
                        return err;
                }
        }

        /* 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_gpio = eoc_gpio;
        data->eoc_irq = 0;

        /* id will be NULL when enumerated via ACPI */
        if (id) {
                chipset = (enum asahi_compass_chipset)(id->driver_data);
                name = id->name;
        } else if (ACPI_HANDLE(&client->dev))
                name = ak8975_match_acpi_device(&client->dev, &chipset);
        else
                return -ENOSYS;

        if (chipset >= AK_MAX_TYPE) {
                dev_err(&client->dev, "AKM device type unsupported: %d\n",
                        chipset);
                return -ENODEV;
        }

        data->def = &ak_def_array[chipset];
        err = ak8975_who_i_am(client, data->def->type);
        if (err < 0) {
                dev_err(&client->dev, "Unexpected device\n");
                return err;
        }
        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);
                return err;
        }

        mutex_init(&data->lock);
        indio_dev->dev.parent = &client->dev;
        indio_dev->channels = ak8975_channels;
        indio_dev->num_channels = ARRAY_SIZE(ak8975_channels);
        indio_dev->info = &ak8975_info;
        indio_dev->modes = INDIO_DIRECT_MODE;
        indio_dev->name = name;
        return devm_iio_device_register(&client->dev, indio_dev);
}

static const struct i2c_device_id ak8975_id[] = {
        {"ak8975", AK8975},
        {"ak8963", AK8963},
        {"AK8963", AK8963},
        {"ak09911", AK09911},
        {"ak09912", AK09912},
        {}
};

MODULE_DEVICE_TABLE(i2c, ak8975_id);

static const struct of_device_id ak8975_of_match[] = {
        { .compatible = "asahi-kasei,ak8975", },
        { .compatible = "ak8975", },
        { .compatible = "asahi-kasei,ak8963", },
        { .compatible = "ak8963", },
        { .compatible = "asahi-kasei,ak09911", },
        { .compatible = "ak09911", },
        { .compatible = "asahi-kasei,ak09912", },
        { .compatible = "ak09912", },
        {}
};
MODULE_DEVICE_TABLE(of, ak8975_of_match);

static struct i2c_driver ak8975_driver = {
        .driver = {
                .name   = "ak8975",
                .of_match_table = of_match_ptr(ak8975_of_match),
                .acpi_match_table = ACPI_PTR(ak_acpi_match),
        },
        .probe          = ak8975_probe,
        .id_table       = ak8975_id,
};
module_i2c_driver(ak8975_driver);

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