// SPDX-License-Identifier: GPL-2.0-only
/*
 * IIO driver for the 3-axis accelerometer Domintech ARD10.
 *
 * Copyright (c) 2016 Hans de Goede <hdegoede@redhat.com>
 * Copyright (c) 2012 Domintech Technology Co., Ltd
 */

#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
#include <linux/byteorder/generic.h>

#define DMARD10_REG_ACTR                        0x00
#define DMARD10_REG_AFEM                        0x0c
#define DMARD10_REG_STADR                       0x12
#define DMARD10_REG_STAINT                      0x1c
#define DMARD10_REG_MISC2                       0x1f
#define DMARD10_REG_PD                          0x21

#define DMARD10_MODE_OFF                        0x00
#define DMARD10_MODE_STANDBY                    0x02
#define DMARD10_MODE_ACTIVE                     0x06
#define DMARD10_MODE_READ_OTP                   0x12
#define DMARD10_MODE_RESET_DATA_PATH            0x82

/* AFEN set 1, ATM[2:0]=b'000 (normal), EN_Z/Y/X/T=1 */
#define DMARD10_VALUE_AFEM_AFEN_NORMAL          0x8f
/* ODR[3:0]=b'0111 (100Hz), CCK[3:0]=b'0100 (204.8kHZ) */
#define DMARD10_VALUE_CKSEL_ODR_100_204         0x74
/* INTC[6:5]=b'00 */
#define DMARD10_VALUE_INTC                      0x00
/* TAP1/TAP2 Average 2 */
#define DMARD10_VALUE_TAPNS_AVE_2               0x11

#define DMARD10_VALUE_STADR                     0x55
#define DMARD10_VALUE_STAINT                    0xaa
#define DMARD10_VALUE_MISC2_OSCA_EN             0x08
#define DMARD10_VALUE_PD_RST                    0x52

/* Offsets into the buffer read in dmard10_read_raw() */
#define DMARD10_X_OFFSET                        1
#define DMARD10_Y_OFFSET                        2
#define DMARD10_Z_OFFSET                        3

/*
 * a value of + or -128 corresponds to + or - 1G
 * scale = 9.81 / 128 = 0.076640625
 */

static const int dmard10_nscale = 76640625;

#define DMARD10_CHANNEL(reg, axis) {    \
        .type = IIO_ACCEL,      \
        .address = reg, \
        .modified = 1,  \
        .channel2 = IIO_MOD_##axis,     \
        .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),   \
        .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
}

static const struct iio_chan_spec dmard10_channels[] = {
        DMARD10_CHANNEL(DMARD10_X_OFFSET, X),
        DMARD10_CHANNEL(DMARD10_Y_OFFSET, Y),
        DMARD10_CHANNEL(DMARD10_Z_OFFSET, Z),
};

struct dmard10_data {
        struct i2c_client *client;
};

/* Init sequence taken from the android driver */
static int dmard10_reset(struct i2c_client *client)
{
        unsigned char buffer[7];
        int ret;

        /* 1. Powerdown reset */
        ret = i2c_smbus_write_byte_data(client, DMARD10_REG_PD,
                                                DMARD10_VALUE_PD_RST);
        if (ret < 0)
                return ret;

        /*
         * 2. ACTR => Standby mode => Download OTP to parameter reg =>
         *    Standby mode => Reset data path => Standby mode
         */
        buffer[0] = DMARD10_REG_ACTR;
        buffer[1] = DMARD10_MODE_STANDBY;
        buffer[2] = DMARD10_MODE_READ_OTP;
        buffer[3] = DMARD10_MODE_STANDBY;
        buffer[4] = DMARD10_MODE_RESET_DATA_PATH;
        buffer[5] = DMARD10_MODE_STANDBY;
        ret = i2c_master_send(client, buffer, 6);
        if (ret < 0)
                return ret;

        /* 3. OSCA_EN = 1, TSTO = b'000 (INT1 = normal, TEST0 = normal) */
        ret = i2c_smbus_write_byte_data(client, DMARD10_REG_MISC2,
                                                DMARD10_VALUE_MISC2_OSCA_EN);
        if (ret < 0)
                return ret;

        /* 4. AFEN = 1 (AFE will powerdown after ADC) */
        buffer[0] = DMARD10_REG_AFEM;
        buffer[1] = DMARD10_VALUE_AFEM_AFEN_NORMAL;
        buffer[2] = DMARD10_VALUE_CKSEL_ODR_100_204;
        buffer[3] = DMARD10_VALUE_INTC;
        buffer[4] = DMARD10_VALUE_TAPNS_AVE_2;
        buffer[5] = 0x00; /* DLYC, no delay timing */
        buffer[6] = 0x07; /* INTD=1 push-pull, INTA=1 active high, AUTOT=1 */
        ret = i2c_master_send(client, buffer, 7);
        if (ret < 0)
                return ret;

        /* 5. Activation mode */
        ret = i2c_smbus_write_byte_data(client, DMARD10_REG_ACTR,
                                                DMARD10_MODE_ACTIVE);
        if (ret < 0)
                return ret;

        return 0;
}

/* Shutdown sequence taken from the android driver */
static int dmard10_shutdown(struct i2c_client *client)
{
        unsigned char buffer[3];

        buffer[0] = DMARD10_REG_ACTR;
        buffer[1] = DMARD10_MODE_STANDBY;
        buffer[2] = DMARD10_MODE_OFF;

        return i2c_master_send(client, buffer, 3);
}

static int dmard10_read_raw(struct iio_dev *indio_dev,
                                struct iio_chan_spec const *chan,
                                int *val, int *val2, long mask)
{
        struct dmard10_data *data = iio_priv(indio_dev);
        __le16 buf[4];
        int ret;

        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                /*
                 * Read 8 bytes starting at the REG_STADR register, trying to
                 * read the individual X, Y, Z registers will always read 0.
                 */
                ret = i2c_smbus_read_i2c_block_data(data->client,
                                                    DMARD10_REG_STADR,
                                                    sizeof(buf), (u8 *)buf);
                if (ret < 0)
                        return ret;
                ret = le16_to_cpu(buf[chan->address]);
                *val = sign_extend32(ret, 12);
                return IIO_VAL_INT;
        case IIO_CHAN_INFO_SCALE:
                *val = 0;
                *val2 = dmard10_nscale;
                return IIO_VAL_INT_PLUS_NANO;
        default:
                return -EINVAL;
        }
}

static const struct iio_info dmard10_info = {
        .read_raw       = dmard10_read_raw,
};

static void dmard10_shutdown_cleanup(void *client)
{
        dmard10_shutdown(client);
}

static int dmard10_probe(struct i2c_client *client)
{
        int ret;
        struct iio_dev *indio_dev;
        struct dmard10_data *data;

        /* These 2 registers have special POR reset values used for id */
        ret = i2c_smbus_read_byte_data(client, DMARD10_REG_STADR);
        if (ret != DMARD10_VALUE_STADR)
                return (ret < 0) ? ret : -ENODEV;

        ret = i2c_smbus_read_byte_data(client, DMARD10_REG_STAINT);
        if (ret != DMARD10_VALUE_STAINT)
                return (ret < 0) ? ret : -ENODEV;

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

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

        indio_dev->info = &dmard10_info;
        indio_dev->name = "dmard10";
        indio_dev->modes = INDIO_DIRECT_MODE;
        indio_dev->channels = dmard10_channels;
        indio_dev->num_channels = ARRAY_SIZE(dmard10_channels);

        ret = dmard10_reset(client);
        if (ret < 0)
                return ret;

        ret = devm_add_action_or_reset(&client->dev, dmard10_shutdown_cleanup,
                                       client);
        if (ret)
                return ret;

        return devm_iio_device_register(&client->dev, indio_dev);
}

static int dmard10_suspend(struct device *dev)
{
        return dmard10_shutdown(to_i2c_client(dev));
}

static int dmard10_resume(struct device *dev)
{
        return dmard10_reset(to_i2c_client(dev));
}

static DEFINE_SIMPLE_DEV_PM_OPS(dmard10_pm_ops, dmard10_suspend,
                                dmard10_resume);

static const struct i2c_device_id dmard10_i2c_id[] = {
        { "dmard10" },
        { }
};
MODULE_DEVICE_TABLE(i2c, dmard10_i2c_id);

static struct i2c_driver dmard10_driver = {
        .driver = {
                .name = "dmard10",
                .pm = pm_sleep_ptr(&dmard10_pm_ops),
        },
        .probe          = dmard10_probe,
        .id_table       = dmard10_i2c_id,
};

module_i2c_driver(dmard10_driver);

MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
MODULE_DESCRIPTION("Domintech ARD10 3-Axis Accelerometer driver");
MODULE_LICENSE("GPL v2");