/*
 * ADIS16130 Digital Output, High Precision Angular Rate Sensor 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/list.h>
#include <linux/module.h>

#include "../iio.h"
#include "../sysfs.h"

#define ADIS16130_CON         0x0
#define ADIS16130_CON_RD      (1 << 6)
#define ADIS16130_IOP         0x1

/* 1 = data-ready signal low when unread data on all channels; */
#define ADIS16130_IOP_ALL_RDY (1 << 3)
#define ADIS16130_IOP_SYNC    (1 << 0) /* 1 = synchronization enabled */
#define ADIS16130_RATEDATA    0x8 /* Gyroscope output, rate of rotation */
#define ADIS16130_TEMPDATA    0xA /* Temperature output */
#define ADIS16130_RATECS      0x28 /* Gyroscope channel setup */
#define ADIS16130_RATECS_EN   (1 << 3) /* 1 = channel enable; */
#define ADIS16130_TEMPCS      0x2A /* Temperature channel setup */
#define ADIS16130_TEMPCS_EN   (1 << 3)
#define ADIS16130_RATECONV    0x30
#define ADIS16130_TEMPCONV    0x32
#define ADIS16130_MODE        0x38
#define ADIS16130_MODE_24BIT  (1 << 1) /* 1 = 24-bit resolution; */

/**
 * struct adis16130_state - device instance specific data
 * @us:                 actual spi_device to write data
 * @buf_lock:           mutex to protect tx and rx
 * @buf:                unified tx/rx buffer
 **/
struct adis16130_state {
        struct spi_device               *us;
        struct mutex                    buf_lock;
        u8                              buf[4] ____cacheline_aligned;
};

static int adis16130_spi_read(struct iio_dev *indio_dev, u8 reg_addr, u32 *val)
{
        int ret;
        struct adis16130_state *st = iio_priv(indio_dev);
        struct spi_message msg;
        struct spi_transfer xfer = {
                .tx_buf = st->buf,
                .rx_buf = st->buf,
                .len = 4,
        };

        mutex_lock(&st->buf_lock);

        st->buf[0] = ADIS16130_CON_RD | reg_addr;
        st->buf[1] = st->buf[2] = st->buf[3] = 0;

        spi_message_init(&msg);
        spi_message_add_tail(&xfer, &msg);
        ret = spi_sync(st->us, &msg);
        ret = spi_read(st->us, st->buf, 4);

        if (ret == 0)
                *val = (st->buf[1] << 16) | (st->buf[2] << 8) | st->buf[3];
        mutex_unlock(&st->buf_lock);

        return ret;
}

static int adis16130_read_raw(struct iio_dev *indio_dev,
                              struct iio_chan_spec const *chan,
                              int *val, int *val2,
                              long mask)
{
        int ret;
        u32 temp;

        /* Take the iio_dev status lock */
        mutex_lock(&indio_dev->mlock);
        ret =  adis16130_spi_read(indio_dev, chan->address, &temp);
        mutex_unlock(&indio_dev->mlock);
        if (ret)
                return ret;
        *val = temp;
        return IIO_VAL_INT;
}

static const struct iio_chan_spec adis16130_channels[] = {
        {
                .type = IIO_ANGL_VEL,
                .modified = 1,
                .channel2 = IIO_MOD_Z,
                .address = ADIS16130_RATEDATA,
        }, {
                .type = IIO_TEMP,
                .indexed = 1,
                .channel = 0,
                .address = ADIS16130_TEMPDATA,
        }
};

static const struct iio_info adis16130_info = {
        .read_raw = &adis16130_read_raw,
        .driver_module = THIS_MODULE,
};

static int __devinit adis16130_probe(struct spi_device *spi)
{
        int ret;
        struct adis16130_state *st;
        struct iio_dev *indio_dev;

        /* setup the industrialio driver allocated elements */
        indio_dev = iio_allocate_device(sizeof(*st));
        if (indio_dev == NULL) {
                ret = -ENOMEM;
                goto error_ret;
        }
        st = iio_priv(indio_dev);
        /* this is only used for removal purposes */
        spi_set_drvdata(spi, indio_dev);
        st->us = spi;
        mutex_init(&st->buf_lock);
        indio_dev->name = spi->dev.driver->name;
        indio_dev->channels = adis16130_channels;
        indio_dev->num_channels = ARRAY_SIZE(adis16130_channels);
        indio_dev->dev.parent = &spi->dev;
        indio_dev->info = &adis16130_info;
        indio_dev->modes = INDIO_DIRECT_MODE;

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

        return 0;

error_free_dev:
        iio_free_device(indio_dev);

error_ret:
        return ret;
}

/* fixme, confirm ordering in this function */
static int adis16130_remove(struct spi_device *spi)
{
        iio_device_unregister(spi_get_drvdata(spi));
        iio_free_device(spi_get_drvdata(spi));

        return 0;
}

static struct spi_driver adis16130_driver = {
        .driver = {
                .name = "adis16130",
                .owner = THIS_MODULE,
        },
        .probe = adis16130_probe,
        .remove = __devexit_p(adis16130_remove),
};

static __init int adis16130_init(void)
{
        return spi_register_driver(&adis16130_driver);
}
module_init(adis16130_init);

static __exit void adis16130_exit(void)
{
        spi_unregister_driver(&adis16130_driver);
}
module_exit(adis16130_exit);

MODULE_AUTHOR("Barry Song <21cnbao@gmail.com>");
MODULE_DESCRIPTION("Analog Devices ADIS16130 High Precision Angular Rate");
MODULE_LICENSE("GPL v2");