// SPDX-License-Identifier: GPL-2.0-only
/*
 * AD7887 SPI ADC driver
 *
 * Copyright 2010-2011 Analog Devices Inc.
 */

#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 specific information
 * @int_vref_mv:        the internal reference voltage
 * @channels:           channels specification
 * @num_channels:       number of channels
 * @dual_channels:      channels specification in dual mode
 * @num_dual_channels:  number of channels in dual mode
 */
struct ad7887_chip_info {
        u16                             int_vref_mv;
        const struct iio_chan_spec      *channels;
        unsigned int                    num_channels;
        const struct iio_chan_spec      *dual_channels;
        unsigned int                    num_dual_channels;
};

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) may require 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)] __aligned(IIO_DMA_MINALIGN);
};

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]);
}

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(indio_dev));
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,
        .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:
                if (!iio_device_claim_direct(indio_dev))
                        return -EBUSY;
                ret = ad7887_scan_direct(st, chan->address);
                iio_device_release_direct(indio_dev);

                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;
}

#define AD7887_CHANNEL(x) { \
        .type = IIO_VOLTAGE, \
        .indexed = 1, \
        .channel = (x), \
        .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
        .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
        .address = (x), \
        .scan_index = (x), \
        .scan_type = { \
                .sign = 'u', \
                .realbits = 12, \
                .storagebits = 16, \
                .shift = 0, \
                .endianness = IIO_BE, \
        }, \
}

static const struct iio_chan_spec ad7887_channels[] = {
        AD7887_CHANNEL(0),
        IIO_CHAN_SOFT_TIMESTAMP(1),
};

static const struct iio_chan_spec ad7887_dual_channels[] = {
        AD7887_CHANNEL(0),
        AD7887_CHANNEL(1),
        IIO_CHAN_SOFT_TIMESTAMP(2),
};

static const struct ad7887_chip_info ad7887_chip_info_tbl[] = {
        /*
         * More devices added in future
         */
        [ID_AD7887] = {
                .channels = ad7887_channels,
                .num_channels = ARRAY_SIZE(ad7887_channels),
                .dual_channels = ad7887_dual_channels,
                .num_dual_channels = ARRAY_SIZE(ad7887_dual_channels),
                .int_vref_mv = 2500,
        },
};

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

static void ad7887_reg_disable(void *data)
{
        struct regulator *reg = data;

        regulator_disable(reg);
}

static int ad7887_probe(struct spi_device *spi)
{
        const struct ad7887_platform_data *pdata = dev_get_platdata(&spi->dev);
        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);

        st->reg = devm_regulator_get_optional(&spi->dev, "vref");
        if (IS_ERR(st->reg)) {
                if (PTR_ERR(st->reg) != -ENODEV)
                        return PTR_ERR(st->reg);

                st->reg = NULL;
        }

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

                ret = devm_add_action_or_reset(&spi->dev, ad7887_reg_disable, st->reg);
                if (ret)
                        return ret;
        }

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

        st->spi = spi;

        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 (!st->reg)
                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->dual_channels;
                indio_dev->num_channels = st->chip_info->num_dual_channels;
        } else {
                indio_dev->channels = st->chip_info->channels;
                indio_dev->num_channels = st->chip_info->num_channels;
        }

        ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev,
                        &iio_pollfunc_store_time,
                        &ad7887_trigger_handler, &ad7887_ring_setup_ops);
        if (ret)
                return ret;

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

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,
        .id_table       = ad7887_id,
};
module_spi_driver(ad7887_driver);

MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
MODULE_DESCRIPTION("Analog Devices AD7887 ADC");
MODULE_LICENSE("GPL v2");