/*
 * ADIS16060 Wide Bandwidth Yaw Rate Gyroscope with SPI driver
 *
 * Copyright 2010 Analog Devices Inc.
 *
 * Licensed under the GPL-2 or later.
 */

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

#define ADIS16060_GYRO          0x20 /* Measure Angular Rate (Gyro) */
#define ADIS16060_TEMP_OUT      0x10 /* Measure Temperature */
#define ADIS16060_AIN2          0x80 /* Measure AIN2 */
#define ADIS16060_AIN1          0x40 /* Measure AIN1 */

/**
 * struct adis16060_state - device instance specific data
 * @us_w:               actual spi_device to write config
 * @us_r:               actual spi_device to read back data
 * @buf:                transmit or receive buffer
 * @buf_lock:           mutex to protect tx and rx
 **/
struct adis16060_state {
        struct spi_device               *us_w;
        struct spi_device               *us_r;
        struct mutex                    buf_lock;

        u8 buf[3] ____cacheline_aligned;
};

static struct iio_dev *adis16060_iio_dev;

static int adis16060_spi_write(struct iio_dev *indio_dev, u8 val)
{
        int ret;
        struct adis16060_state *st = iio_priv(indio_dev);

        mutex_lock(&st->buf_lock);
        st->buf[2] = val; /* The last 8 bits clocked in are latched */
        ret = spi_write(st->us_w, st->buf, 3);
        mutex_unlock(&st->buf_lock);

        return ret;
}

static int adis16060_spi_read(struct iio_dev *indio_dev, u16 *val)
{
        int ret;
        struct adis16060_state *st = iio_priv(indio_dev);

        mutex_lock(&st->buf_lock);

        ret = spi_read(st->us_r, st->buf, 3);

        /* The internal successive approximation ADC begins the
         * conversion process on the falling edge of MSEL1 and
         * starts to place data MSB first on the DOUT line at
         * the 6th falling edge of SCLK
         */
        if (ret == 0)
                *val = ((st->buf[0] & 0x3) << 12) |
                        (st->buf[1] << 4) |
                        ((st->buf[2] >> 4) & 0xF);
        mutex_unlock(&st->buf_lock);

        return ret;
}

static int adis16060_read_raw(struct iio_dev *indio_dev,
                              struct iio_chan_spec const *chan,
                              int *val, int *val2,
                              long mask)
{
        u16 tval = 0;
        int ret;

        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                /* Take the iio_dev status lock */
                mutex_lock(&indio_dev->mlock);
                ret = adis16060_spi_write(indio_dev, chan->address);
                if (ret < 0) {
                        mutex_unlock(&indio_dev->mlock);
                        return ret;
                }
                ret = adis16060_spi_read(indio_dev, &tval);
                mutex_unlock(&indio_dev->mlock);
                *val = tval;
                return IIO_VAL_INT;
        case IIO_CHAN_INFO_OFFSET:
                *val = -7;
                *val2 = 461117;
                return IIO_VAL_INT_PLUS_MICRO;
        case IIO_CHAN_INFO_SCALE:
                *val = 0;
                *val2 = 34000;
                return IIO_VAL_INT_PLUS_MICRO;
        }

        return -EINVAL;
}

static const struct iio_info adis16060_info = {
        .read_raw = &adis16060_read_raw,
        .driver_module = THIS_MODULE,
};

static const struct iio_chan_spec adis16060_channels[] = {
        {
                .type = IIO_ANGL_VEL,
                .modified = 1,
                .channel2 = IIO_MOD_Z,
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
                .address = ADIS16060_GYRO,
        }, {
                .type = IIO_VOLTAGE,
                .indexed = 1,
                .channel = 0,
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
                .address = ADIS16060_AIN1,
        }, {
                .type = IIO_VOLTAGE,
                .indexed = 1,
                .channel = 1,
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
                .address = ADIS16060_AIN2,
        }, {
                .type = IIO_TEMP,
                .indexed = 1,
                .channel = 0,
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
                BIT(IIO_CHAN_INFO_OFFSET) | BIT(IIO_CHAN_INFO_SCALE),
                .address = ADIS16060_TEMP_OUT,
        }
};

static int adis16060_r_probe(struct spi_device *spi)
{
        int ret;
        struct adis16060_state *st;
        struct iio_dev *indio_dev;

        /* setup the industrialio driver allocated elements */
        indio_dev = iio_device_alloc(sizeof(*st));
        if (indio_dev == NULL) {
                ret = -ENOMEM;
                goto error_ret;
        }
        /* this is only used for removal purposes */
        spi_set_drvdata(spi, indio_dev);
        st = iio_priv(indio_dev);
        st->us_r = spi;
        mutex_init(&st->buf_lock);

        indio_dev->name = spi->dev.driver->name;
        indio_dev->dev.parent = &spi->dev;
        indio_dev->info = &adis16060_info;
        indio_dev->modes = INDIO_DIRECT_MODE;
        indio_dev->channels = adis16060_channels;
        indio_dev->num_channels = ARRAY_SIZE(adis16060_channels);

        ret = iio_device_register(indio_dev);
        if (ret)
                goto error_free_dev;

        adis16060_iio_dev = indio_dev;
        return 0;

error_free_dev:
        iio_device_free(indio_dev);
error_ret:
        return ret;
}

/* fixme, confirm ordering in this function */
static int adis16060_r_remove(struct spi_device *spi)
{
        iio_device_unregister(spi_get_drvdata(spi));
        iio_device_free(spi_get_drvdata(spi));

        return 0;
}

static int adis16060_w_probe(struct spi_device *spi)
{
        int ret;
        struct iio_dev *indio_dev = adis16060_iio_dev;
        struct adis16060_state *st;
        if (!indio_dev) {
                ret =  -ENODEV;
                goto error_ret;
        }
        st = iio_priv(indio_dev);
        spi_set_drvdata(spi, indio_dev);
        st->us_w = spi;
        return 0;

error_ret:
        return ret;
}

static int adis16060_w_remove(struct spi_device *spi)
{
        return 0;
}

static struct spi_driver adis16060_r_driver = {
        .driver = {
                .name = "adis16060_r",
                .owner = THIS_MODULE,
        },
        .probe = adis16060_r_probe,
        .remove = adis16060_r_remove,
};

static struct spi_driver adis16060_w_driver = {
        .driver = {
                .name = "adis16060_w",
                .owner = THIS_MODULE,
        },
        .probe = adis16060_w_probe,
        .remove = adis16060_w_remove,
};

static __init int adis16060_init(void)
{
        int ret;

        ret = spi_register_driver(&adis16060_r_driver);
        if (ret < 0)
                return ret;

        ret = spi_register_driver(&adis16060_w_driver);
        if (ret < 0) {
                spi_unregister_driver(&adis16060_r_driver);
                return ret;
        }

        return 0;
}
module_init(adis16060_init);

static __exit void adis16060_exit(void)
{
        spi_unregister_driver(&adis16060_w_driver);
        spi_unregister_driver(&adis16060_r_driver);
}
module_exit(adis16060_exit);

MODULE_AUTHOR("Barry Song <21cnbao@gmail.com>");
MODULE_DESCRIPTION("Analog Devices ADIS16060 Yaw Rate Gyroscope Driver");
MODULE_LICENSE("GPL v2");