/*
 * AD7887 SPI ADC driver
 *
 * Copyright 2010-2011 Analog Devices Inc.
 *
 * Licensed under the GPL-2.
 */

#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/sysfs.h>
#include <linux/spi/spi.h>
#include <linux/regulator/consumer.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/bitops.h>

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

#include <linux/iio/trigger_consumer.h>
#include <linux/iio/triggered_buffer.h>

#include <linux/platform_data/ad7887.h>

#define AD7887_REF_DIS          BIT(5)  /* on-chip reference disable */
#define AD7887_DUAL             BIT(4)  /* dual-channel mode */
#define AD7887_CH_AIN1          BIT(3)  /* convert on channel 1, DUAL=1 */
#define AD7887_CH_AIN0          0       /* convert on channel 0, DUAL=0,1 */
#define AD7887_PM_MODE1         0       /* CS based shutdown */
#define AD7887_PM_MODE2         1       /* full on */
#define AD7887_PM_MODE3         2       /* auto shutdown after conversion */
#define AD7887_PM_MODE4         3       /* standby mode */

enum ad7887_channels {
        AD7887_CH0,
        AD7887_CH0_CH1,
        AD7887_CH1,
};

/**
 * struct ad7887_chip_info - chip specifc information
 * @int_vref_mv:        the internal reference voltage
 * @channel:            channel specification
 */
struct ad7887_chip_info {
        u16                             int_vref_mv;
        struct iio_chan_spec            channel[3];
};

struct ad7887_state {
        struct spi_device               *spi;
        const struct ad7887_chip_info   *chip_info;
        struct regulator                *reg;
        struct spi_transfer             xfer[4];
        struct spi_message              msg[3];
        struct spi_message              *ring_msg;
        unsigned char                   tx_cmd_buf[4];

        /*
         * DMA (thus cache coherency maintenance) requires the
         * transfer buffers to live in their own cache lines.
         * Buffer needs to be large enough to hold two 16 bit samples and a
         * 64 bit aligned 64 bit timestamp.
         */
        unsigned char data[ALIGN(4, sizeof(s64)) + sizeof(s64)]
                ____cacheline_aligned;
};

enum ad7887_supported_device_ids {
        ID_AD7887
};

static int ad7887_ring_preenable(struct iio_dev *indio_dev)
{
        struct ad7887_state *st = iio_priv(indio_dev);

        /* We know this is a single long so can 'cheat' */
        switch (*indio_dev->active_scan_mask) {
        case (1 << 0):
                st->ring_msg = &st->msg[AD7887_CH0];
                break;
        case (1 << 1):
                st->ring_msg = &st->msg[AD7887_CH1];
                /* Dummy read: push CH1 setting down to hardware */
                spi_sync(st->spi, st->ring_msg);
                break;
        case ((1 << 1) | (1 << 0)):
                st->ring_msg = &st->msg[AD7887_CH0_CH1];
                break;
        }

        return 0;
}

static int ad7887_ring_postdisable(struct iio_dev *indio_dev)
{
        struct ad7887_state *st = iio_priv(indio_dev);

        /* dummy read: restore default CH0 settin */
        return spi_sync(st->spi, &st->msg[AD7887_CH0]);
}

/**
 * ad7887_trigger_handler() bh of trigger launched polling to ring buffer
 *
 * Currently there is no option in this driver to disable the saving of
 * timestamps within the ring.
 **/
static irqreturn_t ad7887_trigger_handler(int irq, void *p)
{
        struct iio_poll_func *pf = p;
        struct iio_dev *indio_dev = pf->indio_dev;
        struct ad7887_state *st = iio_priv(indio_dev);
        int b_sent;

        b_sent = spi_sync(st->spi, st->ring_msg);
        if (b_sent)
                goto done;

        iio_push_to_buffers_with_timestamp(indio_dev, st->data,
                iio_get_time_ns());
done:
        iio_trigger_notify_done(indio_dev->trig);

        return IRQ_HANDLED;
}

static const struct iio_buffer_setup_ops ad7887_ring_setup_ops = {
        .preenable = &ad7887_ring_preenable,
        .postenable = &iio_triggered_buffer_postenable,
        .predisable = &iio_triggered_buffer_predisable,
        .postdisable = &ad7887_ring_postdisable,
};

static int ad7887_scan_direct(struct ad7887_state *st, unsigned ch)
{
        int ret = spi_sync(st->spi, &st->msg[ch]);
        if (ret)
                return ret;

        return (st->data[(ch * 2)] << 8) | st->data[(ch * 2) + 1];
}

static int ad7887_read_raw(struct iio_dev *indio_dev,
                           struct iio_chan_spec const *chan,
                           int *val,
                           int *val2,
                           long m)
{
        int ret;
        struct ad7887_state *st = iio_priv(indio_dev);

        switch (m) {
        case IIO_CHAN_INFO_RAW:
                mutex_lock(&indio_dev->mlock);
                if (iio_buffer_enabled(indio_dev))
                        ret = -EBUSY;
                else
                        ret = ad7887_scan_direct(st, chan->address);
                mutex_unlock(&indio_dev->mlock);

                if (ret < 0)
                        return ret;
                *val = ret >> chan->scan_type.shift;
                *val &= GENMASK(chan->scan_type.realbits - 1, 0);
                return IIO_VAL_INT;
        case IIO_CHAN_INFO_SCALE:
                if (st->reg) {
                        *val = regulator_get_voltage(st->reg);
                        if (*val < 0)
                                return *val;
                        *val /= 1000;
                } else {
                        *val = st->chip_info->int_vref_mv;
                }

                *val2 = chan->scan_type.realbits;

                return IIO_VAL_FRACTIONAL_LOG2;
        }
        return -EINVAL;
}


static const struct ad7887_chip_info ad7887_chip_info_tbl[] = {
        /*
         * More devices added in future
         */
        [ID_AD7887] = {
                .channel[0] = {
                        .type = IIO_VOLTAGE,
                        .indexed = 1,
                        .channel = 1,
                        .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
                        .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
                        .address = 1,
                        .scan_index = 1,
                        .scan_type = {
                                .sign = 'u',
                                .realbits = 12,
                                .storagebits = 16,
                                .shift = 0,
                                .endianness = IIO_BE,
                        },
                },
                .channel[1] = {
                        .type = IIO_VOLTAGE,
                        .indexed = 1,
                        .channel = 0,
                        .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
                        .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
                        .address = 0,
                        .scan_index = 0,
                        .scan_type = {
                                .sign = 'u',
                                .realbits = 12,
                                .storagebits = 16,
                                .shift = 0,
                                .endianness = IIO_BE,
                        },
                },
                .channel[2] = IIO_CHAN_SOFT_TIMESTAMP(2),
                .int_vref_mv = 2500,
        },
};

static const struct iio_info ad7887_info = {
        .read_raw = &ad7887_read_raw,
        .driver_module = THIS_MODULE,
};

static int ad7887_probe(struct spi_device *spi)
{
        struct ad7887_platform_data *pdata = spi->dev.platform_data;
        struct ad7887_state *st;
        struct iio_dev *indio_dev;
        uint8_t mode;
        int ret;

        indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
        if (indio_dev == NULL)
                return -ENOMEM;

        st = iio_priv(indio_dev);

        if (!pdata || !pdata->use_onchip_ref) {
                st->reg = devm_regulator_get(&spi->dev, "vref");
                if (IS_ERR(st->reg))
                        return PTR_ERR(st->reg);

                ret = regulator_enable(st->reg);
                if (ret)
                        return ret;
        }

        st->chip_info =
                &ad7887_chip_info_tbl[spi_get_device_id(spi)->driver_data];

        spi_set_drvdata(spi, indio_dev);
        st->spi = spi;

        /* Estabilish that the iio_dev is a child of the spi device */
        indio_dev->dev.parent = &spi->dev;
        indio_dev->name = spi_get_device_id(spi)->name;
        indio_dev->info = &ad7887_info;
        indio_dev->modes = INDIO_DIRECT_MODE;

        /* Setup default message */

        mode = AD7887_PM_MODE4;
        if (!pdata || !pdata->use_onchip_ref)
                mode |= AD7887_REF_DIS;
        if (pdata && pdata->en_dual)
                mode |= AD7887_DUAL;

        st->tx_cmd_buf[0] = AD7887_CH_AIN0 | mode;

        st->xfer[0].rx_buf = &st->data[0];
        st->xfer[0].tx_buf = &st->tx_cmd_buf[0];
        st->xfer[0].len = 2;

        spi_message_init(&st->msg[AD7887_CH0]);
        spi_message_add_tail(&st->xfer[0], &st->msg[AD7887_CH0]);

        if (pdata && pdata->en_dual) {
                st->tx_cmd_buf[2] = AD7887_CH_AIN1 | mode;

                st->xfer[1].rx_buf = &st->data[0];
                st->xfer[1].tx_buf = &st->tx_cmd_buf[2];
                st->xfer[1].len = 2;

                st->xfer[2].rx_buf = &st->data[2];
                st->xfer[2].tx_buf = &st->tx_cmd_buf[0];
                st->xfer[2].len = 2;

                spi_message_init(&st->msg[AD7887_CH0_CH1]);
                spi_message_add_tail(&st->xfer[1], &st->msg[AD7887_CH0_CH1]);
                spi_message_add_tail(&st->xfer[2], &st->msg[AD7887_CH0_CH1]);

                st->xfer[3].rx_buf = &st->data[2];
                st->xfer[3].tx_buf = &st->tx_cmd_buf[2];
                st->xfer[3].len = 2;

                spi_message_init(&st->msg[AD7887_CH1]);
                spi_message_add_tail(&st->xfer[3], &st->msg[AD7887_CH1]);

                indio_dev->channels = st->chip_info->channel;
                indio_dev->num_channels = 3;
        } else {
                indio_dev->channels = &st->chip_info->channel[1];
                indio_dev->num_channels = 2;
        }

        ret = iio_triggered_buffer_setup(indio_dev, &iio_pollfunc_store_time,
                        &ad7887_trigger_handler, &ad7887_ring_setup_ops);
        if (ret)
                goto error_disable_reg;

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

        return 0;
error_unregister_ring:
        iio_triggered_buffer_cleanup(indio_dev);
error_disable_reg:
        if (st->reg)
                regulator_disable(st->reg);

        return ret;
}

static int ad7887_remove(struct spi_device *spi)
{
        struct iio_dev *indio_dev = spi_get_drvdata(spi);
        struct ad7887_state *st = iio_priv(indio_dev);

        iio_device_unregister(indio_dev);
        iio_triggered_buffer_cleanup(indio_dev);
        if (st->reg)
                regulator_disable(st->reg);

        return 0;
}

static const struct spi_device_id ad7887_id[] = {
        {"ad7887", ID_AD7887},
        {}
};
MODULE_DEVICE_TABLE(spi, ad7887_id);

static struct spi_driver ad7887_driver = {
        .driver = {
                .name   = "ad7887",
        },
        .probe          = ad7887_probe,
        .remove         = ad7887_remove,
        .id_table       = ad7887_id,
};
module_spi_driver(ad7887_driver);

MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
MODULE_DESCRIPTION("Analog Devices AD7887 ADC");
MODULE_LICENSE("GPL v2");