// SPDX-License-Identifier: GPL-2.0
/*
 * AD8366 and similar Gain Amplifiers
 * This driver supports the following gain amplifiers:
 *   AD8366 Dual-Digital Variable Gain Amplifier (VGA)
 *   ADA4961 BiCMOS RF Digital Gain Amplifier (DGA)
 *   ADL5240 Digitally controlled variable gain amplifier (VGA)
 *   HMC792A 0.25 dB LSB GaAs MMIC 6-Bit Digital Attenuator
 *   HMC1119 0.25 dB LSB, 7-Bit, Silicon Digital Attenuator
 *
 * Copyright 2012-2019 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/gpio/consumer.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/bitrev.h>

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

enum ad8366_type {
        ID_AD8366,
        ID_ADA4961,
        ID_ADL5240,
        ID_HMC792,
        ID_HMC1119,
};

struct ad8366_info {
        int gain_min;
        int gain_max;
};

struct ad8366_state {
        struct spi_device       *spi;
        struct regulator        *reg;
        struct mutex            lock; /* protect sensor state */
        struct gpio_desc        *reset_gpio;
        unsigned char           ch[2];
        enum ad8366_type        type;
        const struct ad8366_info *info;
        /*
         * DMA (thus cache coherency maintenance) may require the
         * transfer buffers to live in their own cache lines.
         */
        unsigned char           data[2] __aligned(IIO_DMA_MINALIGN);
};

static const struct ad8366_info ad8366_infos[] = {
        [ID_AD8366] = {
                .gain_min = 4500,
                .gain_max = 20500,
        },
        [ID_ADA4961] = {
                .gain_min = -6000,
                .gain_max = 15000,
        },
        [ID_ADL5240] = {
                .gain_min = -11500,
                .gain_max = 20000,
        },
        [ID_HMC792] = {
                .gain_min = -15750,
                .gain_max = 0,
        },
        [ID_HMC1119] = {
                .gain_min = -31750,
                .gain_max = 0,
        },
};

static int ad8366_write(struct iio_dev *indio_dev,
                        unsigned char ch_a, unsigned char ch_b)
{
        struct ad8366_state *st = iio_priv(indio_dev);
        int ret;

        switch (st->type) {
        case ID_AD8366:
                ch_a = bitrev8(ch_a & 0x3F);
                ch_b = bitrev8(ch_b & 0x3F);

                st->data[0] = ch_b >> 4;
                st->data[1] = (ch_b << 4) | (ch_a >> 2);
                break;
        case ID_ADA4961:
                st->data[0] = ch_a & 0x1F;
                break;
        case ID_ADL5240:
                st->data[0] = (ch_a & 0x3F);
                break;
        case ID_HMC792:
        case ID_HMC1119:
                st->data[0] = ch_a;
                break;
        }

        ret = spi_write(st->spi, st->data, indio_dev->num_channels);
        if (ret < 0)
                dev_err(&indio_dev->dev, "write failed (%d)", ret);

        return ret;
}

static int ad8366_read_raw(struct iio_dev *indio_dev,
                           struct iio_chan_spec const *chan,
                           int *val,
                           int *val2,
                           long m)
{
        struct ad8366_state *st = iio_priv(indio_dev);
        int ret;
        int code, gain = 0;

        mutex_lock(&st->lock);
        switch (m) {
        case IIO_CHAN_INFO_HARDWAREGAIN:
                code = st->ch[chan->channel];

                switch (st->type) {
                case ID_AD8366:
                        gain = code * 253 + 4500;
                        break;
                case ID_ADA4961:
                        gain = 15000 - code * 1000;
                        break;
                case ID_ADL5240:
                        gain = 20000 - 31500 + code * 500;
                        break;
                case ID_HMC792:
                        gain = -1 * code * 500;
                        break;
                case ID_HMC1119:
                        gain = -1 * code * 250;
                        break;
                }

                /* Values in dB */
                *val = gain / 1000;
                *val2 = (gain % 1000) * 1000;

                ret = IIO_VAL_INT_PLUS_MICRO_DB;
                break;
        default:
                ret = -EINVAL;
        }
        mutex_unlock(&st->lock);

        return ret;
};

static int ad8366_write_raw(struct iio_dev *indio_dev,
                            struct iio_chan_spec const *chan,
                            int val,
                            int val2,
                            long mask)
{
        struct ad8366_state *st = iio_priv(indio_dev);
        const struct ad8366_info *inf = st->info;
        int code = 0, gain;
        int ret;

        /* Values in dB */
        if (val < 0)
                gain = (val * 1000) - (val2 / 1000);
        else
                gain = (val * 1000) + (val2 / 1000);

        if (gain > inf->gain_max || gain < inf->gain_min)
                return -EINVAL;

        switch (st->type) {
        case ID_AD8366:
                code = (gain - 4500) / 253;
                break;
        case ID_ADA4961:
                code = (15000 - gain) / 1000;
                break;
        case ID_ADL5240:
                code = ((gain - 500 - 20000) / 500) & 0x3F;
                break;
        case ID_HMC792:
                code = (abs(gain) / 500) & 0x3F;
                break;
        case ID_HMC1119:
                code = (abs(gain) / 250) & 0x7F;
                break;
        }

        mutex_lock(&st->lock);
        switch (mask) {
        case IIO_CHAN_INFO_HARDWAREGAIN:
                st->ch[chan->channel] = code;
                ret = ad8366_write(indio_dev, st->ch[0], st->ch[1]);
                break;
        default:
                ret = -EINVAL;
        }
        mutex_unlock(&st->lock);

        return ret;
}

static int ad8366_write_raw_get_fmt(struct iio_dev *indio_dev,
                                    struct iio_chan_spec const *chan,
                                    long mask)
{
        switch (mask) {
        case IIO_CHAN_INFO_HARDWAREGAIN:
                return IIO_VAL_INT_PLUS_MICRO_DB;
        default:
                return -EINVAL;
        }
}

static const struct iio_info ad8366_info = {
        .read_raw = &ad8366_read_raw,
        .write_raw = &ad8366_write_raw,
        .write_raw_get_fmt = &ad8366_write_raw_get_fmt,
};

#define AD8366_CHAN(_channel) {                         \
        .type = IIO_VOLTAGE,                            \
        .output = 1,                                    \
        .indexed = 1,                                   \
        .channel = _channel,                            \
        .info_mask_separate = BIT(IIO_CHAN_INFO_HARDWAREGAIN),\
}

static const struct iio_chan_spec ad8366_channels[] = {
        AD8366_CHAN(0),
        AD8366_CHAN(1),
};

static const struct iio_chan_spec ada4961_channels[] = {
        AD8366_CHAN(0),
};

static int ad8366_probe(struct spi_device *spi)
{
        struct iio_dev *indio_dev;
        struct ad8366_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->reg = devm_regulator_get(&spi->dev, "vcc");
        if (!IS_ERR(st->reg)) {
                ret = regulator_enable(st->reg);
                if (ret)
                        return ret;
        }

        spi_set_drvdata(spi, indio_dev);
        mutex_init(&st->lock);
        st->spi = spi;
        st->type = spi_get_device_id(spi)->driver_data;

        switch (st->type) {
        case ID_AD8366:
                indio_dev->channels = ad8366_channels;
                indio_dev->num_channels = ARRAY_SIZE(ad8366_channels);
                break;
        case ID_ADA4961:
        case ID_ADL5240:
        case ID_HMC792:
        case ID_HMC1119:
                st->reset_gpio = devm_gpiod_get_optional(&spi->dev, "reset", GPIOD_OUT_HIGH);
                if (IS_ERR(st->reset_gpio)) {
                        ret = PTR_ERR(st->reset_gpio);
                        goto error_disable_reg;
                }
                indio_dev->channels = ada4961_channels;
                indio_dev->num_channels = ARRAY_SIZE(ada4961_channels);
                break;
        default:
                dev_err(&spi->dev, "Invalid device ID\n");
                ret = -EINVAL;
                goto error_disable_reg;
        }

        st->info = &ad8366_infos[st->type];
        indio_dev->name = spi_get_device_id(spi)->name;
        indio_dev->info = &ad8366_info;
        indio_dev->modes = INDIO_DIRECT_MODE;

        ret = ad8366_write(indio_dev, 0, 0);
        if (ret < 0)
                goto error_disable_reg;

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

        return 0;

error_disable_reg:
        if (!IS_ERR(st->reg))
                regulator_disable(st->reg);

        return ret;
}

static void ad8366_remove(struct spi_device *spi)
{
        struct iio_dev *indio_dev = spi_get_drvdata(spi);
        struct ad8366_state *st = iio_priv(indio_dev);
        struct regulator *reg = st->reg;

        iio_device_unregister(indio_dev);

        if (!IS_ERR(reg))
                regulator_disable(reg);
}

static const struct spi_device_id ad8366_id[] = {
        {"ad8366",  ID_AD8366},
        {"ada4961", ID_ADA4961},
        {"adl5240", ID_ADL5240},
        {"hmc792a", ID_HMC792},
        {"hmc1119", ID_HMC1119},
        { }
};
MODULE_DEVICE_TABLE(spi, ad8366_id);

static struct spi_driver ad8366_driver = {
        .driver = {
                .name   = KBUILD_MODNAME,
        },
        .probe          = ad8366_probe,
        .remove         = ad8366_remove,
        .id_table       = ad8366_id,
};

module_spi_driver(ad8366_driver);

MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
MODULE_DESCRIPTION("Analog Devices AD8366 and similar Gain Amplifiers");
MODULE_LICENSE("GPL v2");