/*
 * ADIS16080/100 Yaw Rate Gyroscope with SPI driver
 *
 * Copyright 2010 Analog Devices Inc.
 *
 * Licensed under the GPL-2 or later.
 */
#include <linux/delay.h>
#include <linux/mutex.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/spi/spi.h>
#include <linux/slab.h>
#include <linux/sysfs.h>
#include <linux/module.h>

#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>

#define ADIS16080_DIN_GYRO   (0 << 10) /* Gyroscope output */
#define ADIS16080_DIN_TEMP   (1 << 10) /* Temperature output */
#define ADIS16080_DIN_AIN1   (2 << 10)
#define ADIS16080_DIN_AIN2   (3 << 10)

/*
 * 1: Write contents on DIN to control register.
 * 0: No changes to control register.
 */

#define ADIS16080_DIN_WRITE  (1 << 15)

struct adis16080_chip_info {
        int scale_val;
        int scale_val2;
};

/**
 * struct adis16080_state - device instance specific data
 * @us:                 actual spi_device to write data
 * @info:               chip specific parameters
 * @buf:                transmit or receive buffer
 **/
struct adis16080_state {
        struct spi_device               *us;
        const struct adis16080_chip_info *info;

        __be16 buf ____cacheline_aligned;
};

static int adis16080_read_sample(struct iio_dev *indio_dev,
                u16 addr, int *val)
{
        struct adis16080_state *st = iio_priv(indio_dev);
        int ret;
        struct spi_transfer     t[] = {
                {
                        .tx_buf         = &st->buf,
                        .len            = 2,
                        .cs_change      = 1,
                }, {
                        .rx_buf         = &st->buf,
                        .len            = 2,
                },
        };

        st->buf = cpu_to_be16(addr | ADIS16080_DIN_WRITE);

        ret = spi_sync_transfer(st->us, t, ARRAY_SIZE(t));
        if (ret == 0)
                *val = sign_extend32(be16_to_cpu(st->buf), 11);

        return ret;
}

static int adis16080_read_raw(struct iio_dev *indio_dev,
                             struct iio_chan_spec const *chan,
                             int *val,
                             int *val2,
                             long mask)
{
        struct adis16080_state *st = iio_priv(indio_dev);
        int ret;

        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                mutex_lock(&indio_dev->mlock);
                ret = adis16080_read_sample(indio_dev, chan->address, val);
                mutex_unlock(&indio_dev->mlock);
                return ret ? ret : IIO_VAL_INT;
        case IIO_CHAN_INFO_SCALE:
                switch (chan->type) {
                case IIO_ANGL_VEL:
                        *val = st->info->scale_val;
                        *val2 = st->info->scale_val2;
                        return IIO_VAL_FRACTIONAL;
                case IIO_VOLTAGE:
                        /* VREF = 5V, 12 bits */
                        *val = 5000;
                        *val2 = 12;
                        return IIO_VAL_FRACTIONAL_LOG2;
                case IIO_TEMP:
                        /* 85 C = 585, 25 C = 0 */
                        *val = 85000 - 25000;
                        *val2 = 585;
                        return IIO_VAL_FRACTIONAL;
                default:
                        return -EINVAL;
                }
        case IIO_CHAN_INFO_OFFSET:
                switch (chan->type) {
                case IIO_VOLTAGE:
                        /* 2.5 V = 0 */
                        *val = 2048;
                        return IIO_VAL_INT;
                case IIO_TEMP:
                        /* 85 C = 585, 25 C = 0 */
                        *val = DIV_ROUND_CLOSEST(25 * 585, 85 - 25);
                        return IIO_VAL_INT;
                default:
                        return -EINVAL;
                }
        default:
                break;
        }

        return -EINVAL;
}

static const struct iio_chan_spec adis16080_channels[] = {
        {
                .type = IIO_ANGL_VEL,
                .modified = 1,
                .channel2 = IIO_MOD_Z,
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
                        BIT(IIO_CHAN_INFO_SCALE),
                .address = ADIS16080_DIN_GYRO,
        }, {
                .type = IIO_VOLTAGE,
                .indexed = 1,
                .channel = 0,
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
                        BIT(IIO_CHAN_INFO_SCALE) |
                        BIT(IIO_CHAN_INFO_OFFSET),
                .address = ADIS16080_DIN_AIN1,
        }, {
                .type = IIO_VOLTAGE,
                .indexed = 1,
                .channel = 1,
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
                        BIT(IIO_CHAN_INFO_SCALE) |
                        BIT(IIO_CHAN_INFO_OFFSET),
                .address = ADIS16080_DIN_AIN2,
        }, {
                .type = IIO_TEMP,
                .indexed = 1,
                .channel = 0,
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
                        BIT(IIO_CHAN_INFO_SCALE) |
                        BIT(IIO_CHAN_INFO_OFFSET),
                .address = ADIS16080_DIN_TEMP,
        }
};

static const struct iio_info adis16080_info = {
        .read_raw = &adis16080_read_raw,
};

enum {
        ID_ADIS16080,
        ID_ADIS16100,
};

static const struct adis16080_chip_info adis16080_chip_info[] = {
        [ID_ADIS16080] = {
                /* 80 degree = 819, 819 rad = 46925 degree */
                .scale_val = 80,
                .scale_val2 = 46925,
        },
        [ID_ADIS16100] = {
                /* 300 degree = 1230, 1230 rad = 70474 degree */
                .scale_val = 300,
                .scale_val2 = 70474,
        },
};

static int adis16080_probe(struct spi_device *spi)
{
        const struct spi_device_id *id = spi_get_device_id(spi);
        struct adis16080_state *st;
        struct iio_dev *indio_dev;

        /* setup the industrialio driver allocated elements */
        indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
        if (!indio_dev)
                return -ENOMEM;
        st = iio_priv(indio_dev);
        /* this is only used for removal purposes */
        spi_set_drvdata(spi, indio_dev);

        /* Allocate the comms buffers */
        st->us = spi;
        st->info = &adis16080_chip_info[id->driver_data];

        indio_dev->name = spi->dev.driver->name;
        indio_dev->channels = adis16080_channels;
        indio_dev->num_channels = ARRAY_SIZE(adis16080_channels);
        indio_dev->dev.parent = &spi->dev;
        indio_dev->info = &adis16080_info;
        indio_dev->modes = INDIO_DIRECT_MODE;

        return iio_device_register(indio_dev);
}

static int adis16080_remove(struct spi_device *spi)
{
        iio_device_unregister(spi_get_drvdata(spi));
        return 0;
}

static const struct spi_device_id adis16080_ids[] = {
        { "adis16080", ID_ADIS16080 },
        { "adis16100", ID_ADIS16100 },
        {},
};
MODULE_DEVICE_TABLE(spi, adis16080_ids);

static struct spi_driver adis16080_driver = {
        .driver = {
                .name = "adis16080",
        },
        .probe = adis16080_probe,
        .remove = adis16080_remove,
        .id_table = adis16080_ids,
};
module_spi_driver(adis16080_driver);

MODULE_AUTHOR("Barry Song <21cnbao@gmail.com>");
MODULE_DESCRIPTION("Analog Devices ADIS16080/100 Yaw Rate Gyroscope Driver");
MODULE_LICENSE("GPL v2");