// SPDX-License-Identifier: GPL-2.0-only
/*
 * AD7303 Digital to analog converters driver
 *
 * Copyright 2013 Analog Devices Inc.
 */

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

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

#define AD7303_CFG_EXTERNAL_VREF BIT(15)
#define AD7303_CFG_POWER_DOWN(ch) BIT(11 + (ch))
#define AD7303_CFG_ADDR_OFFSET  10

#define AD7303_CMD_UPDATE_DAC   (0x3 << 8)

/**
 * struct ad7303_state - driver instance specific data
 * @spi:                the device for this driver instance
 * @config:             cached config register value
 * @dac_cache:          current DAC raw value (chip does not support readback)
 * @vdd_reg:            reference to VDD regulator
 * @vref_reg:           reference to VREF regulator
 * @lock:               protect writes and cache updates
 * @data:               spi transfer buffer
 */

struct ad7303_state {
        struct spi_device *spi;
        uint16_t config;
        uint8_t dac_cache[2];

        struct regulator *vdd_reg;
        struct regulator *vref_reg;

        struct mutex lock;
        /*
         * DMA (thus cache coherency maintenance) may require the
         * transfer buffers to live in their own cache lines.
         */
        __be16 data __aligned(IIO_DMA_MINALIGN);
};

static int ad7303_write(struct ad7303_state *st, unsigned int chan,
        uint8_t val)
{
        st->data = cpu_to_be16(AD7303_CMD_UPDATE_DAC |
                (chan << AD7303_CFG_ADDR_OFFSET) |
                st->config | val);

        return spi_write(st->spi, &st->data, sizeof(st->data));
}

static ssize_t ad7303_read_dac_powerdown(struct iio_dev *indio_dev,
        uintptr_t private, const struct iio_chan_spec *chan, char *buf)
{
        struct ad7303_state *st = iio_priv(indio_dev);

        return sysfs_emit(buf, "%d\n", (bool)(st->config &
                AD7303_CFG_POWER_DOWN(chan->channel)));
}

static ssize_t ad7303_write_dac_powerdown(struct iio_dev *indio_dev,
         uintptr_t private, const struct iio_chan_spec *chan, const char *buf,
         size_t len)
{
        struct ad7303_state *st = iio_priv(indio_dev);
        bool pwr_down;
        int ret;

        ret = kstrtobool(buf, &pwr_down);
        if (ret)
                return ret;

        mutex_lock(&st->lock);

        if (pwr_down)
                st->config |= AD7303_CFG_POWER_DOWN(chan->channel);
        else
                st->config &= ~AD7303_CFG_POWER_DOWN(chan->channel);

        /* There is no noop cmd which allows us to only update the powerdown
         * mode, so just write one of the DAC channels again */
        ad7303_write(st, chan->channel, st->dac_cache[chan->channel]);

        mutex_unlock(&st->lock);
        return len;
}

static int ad7303_get_vref(struct ad7303_state *st,
        struct iio_chan_spec const *chan)
{
        int ret;

        if (st->config & AD7303_CFG_EXTERNAL_VREF)
                return regulator_get_voltage(st->vref_reg);

        ret = regulator_get_voltage(st->vdd_reg);
        if (ret < 0)
                return ret;
        return ret / 2;
}

static int ad7303_read_raw(struct iio_dev *indio_dev,
        struct iio_chan_spec const *chan, int *val, int *val2, long info)
{
        struct ad7303_state *st = iio_priv(indio_dev);
        int vref_uv;

        switch (info) {
        case IIO_CHAN_INFO_RAW:
                mutex_lock(&st->lock);
                *val = st->dac_cache[chan->channel];
                mutex_unlock(&st->lock);
                return IIO_VAL_INT;
        case IIO_CHAN_INFO_SCALE:
                vref_uv = ad7303_get_vref(st, chan);
                if (vref_uv < 0)
                        return vref_uv;

                *val = 2 * vref_uv / 1000;
                *val2 = chan->scan_type.realbits;

                return IIO_VAL_FRACTIONAL_LOG2;
        default:
                break;
        }
        return -EINVAL;
}

static int ad7303_write_raw(struct iio_dev *indio_dev,
        struct iio_chan_spec const *chan, int val, int val2, long mask)
{
        struct ad7303_state *st = iio_priv(indio_dev);
        int ret;

        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                if (val >= (1 << chan->scan_type.realbits) || val < 0)
                        return -EINVAL;

                mutex_lock(&st->lock);
                ret = ad7303_write(st, chan->address, val);
                if (ret == 0)
                        st->dac_cache[chan->channel] = val;
                mutex_unlock(&st->lock);
                break;
        default:
                ret = -EINVAL;
        }

        return ret;
}

static const struct iio_info ad7303_info = {
        .read_raw = ad7303_read_raw,
        .write_raw = ad7303_write_raw,
};

static const struct iio_chan_spec_ext_info ad7303_ext_info[] = {
        {
                .name = "powerdown",
                .read = ad7303_read_dac_powerdown,
                .write = ad7303_write_dac_powerdown,
                .shared = IIO_SEPARATE,
        },
        { }
};

#define AD7303_CHANNEL(chan) {                                  \
        .type = IIO_VOLTAGE,                                    \
        .indexed = 1,                                           \
        .output = 1,                                            \
        .channel = (chan),                                      \
        .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
        .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
        .address = (chan),                                      \
        .scan_type = {                                          \
                .sign = 'u',                                    \
                .realbits = 8,                                  \
                .storagebits = 8,                               \
                .shift = 0,                                     \
        },                                                      \
        .ext_info = ad7303_ext_info,                            \
}

static const struct iio_chan_spec ad7303_channels[] = {
        AD7303_CHANNEL(0),
        AD7303_CHANNEL(1),
};

static void ad7303_reg_disable(void *reg)
{
        regulator_disable(reg);
}

static int ad7303_probe(struct spi_device *spi)
{
        const struct spi_device_id *id = spi_get_device_id(spi);
        struct iio_dev *indio_dev;
        struct ad7303_state *st;
        int ret;

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

        st = iio_priv(indio_dev);

        st->spi = spi;

        mutex_init(&st->lock);

        st->vdd_reg = devm_regulator_get(&spi->dev, "Vdd");
        if (IS_ERR(st->vdd_reg))
                return PTR_ERR(st->vdd_reg);

        ret = regulator_enable(st->vdd_reg);
        if (ret)
                return ret;

        ret = devm_add_action_or_reset(&spi->dev, ad7303_reg_disable, st->vdd_reg);
        if (ret)
                return ret;

        st->vref_reg = devm_regulator_get_optional(&spi->dev, "REF");
        if (IS_ERR(st->vref_reg)) {
                ret = PTR_ERR(st->vref_reg);
                if (ret != -ENODEV)
                        return ret;
                st->vref_reg = NULL;
        }

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

                ret = devm_add_action_or_reset(&spi->dev, ad7303_reg_disable,
                                               st->vref_reg);
                if (ret)
                        return ret;

                st->config |= AD7303_CFG_EXTERNAL_VREF;
        }

        indio_dev->name = id->name;
        indio_dev->info = &ad7303_info;
        indio_dev->modes = INDIO_DIRECT_MODE;
        indio_dev->channels = ad7303_channels;
        indio_dev->num_channels = ARRAY_SIZE(ad7303_channels);

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

static const struct of_device_id ad7303_spi_of_match[] = {
        { .compatible = "adi,ad7303", },
        { }
};
MODULE_DEVICE_TABLE(of, ad7303_spi_of_match);

static const struct spi_device_id ad7303_spi_ids[] = {
        { "ad7303", 0 },
        { }
};
MODULE_DEVICE_TABLE(spi, ad7303_spi_ids);

static struct spi_driver ad7303_driver = {
        .driver = {
                .name = "ad7303",
                .of_match_table = ad7303_spi_of_match,
        },
        .probe = ad7303_probe,
        .id_table = ad7303_spi_ids,
};
module_spi_driver(ad7303_driver);

MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
MODULE_DESCRIPTION("Analog Devices AD7303 DAC driver");
MODULE_LICENSE("GPL v2");