// SPDX-License-Identifier: GPL-2.0-only
/*
 * ad2s1200.c simple support for the ADI Resolver to Digital Converters:
 * AD2S1200/1205
 *
 * Copyright (c) 2018-2018 David Veenstra <davidjulianveenstra@gmail.com>
 * Copyright (c) 2010-2010 Analog Devices Inc.
 */

#include <linux/bitops.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/gpio/consumer.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/mutex.h>
#include <linux/spi/spi.h>
#include <linux/sysfs.h>
#include <linux/types.h>

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


/* input clock on serial interface */
#define AD2S1200_HZ     8192000
/* clock period in nano second */
#define AD2S1200_TSCLK  (1000000000 / AD2S1200_HZ)

/**
 * struct ad2s1200_state - driver instance specific data.
 * @lock:       protects both the GPIO pins and the rx buffer.
 * @sdev:       spi device.
 * @sample:     GPIO pin SAMPLE.
 * @rdvel:      GPIO pin RDVEL.
 * @rx:         buffer for spi transfers.
 */
struct ad2s1200_state {
        struct mutex lock;
        struct spi_device *sdev;
        struct gpio_desc *sample;
        struct gpio_desc *rdvel;
        __be16 rx __aligned(IIO_DMA_MINALIGN);
};

static int ad2s1200_read_raw(struct iio_dev *indio_dev,
                             struct iio_chan_spec const *chan,
                             int *val,
                             int *val2,
                             long m)
{
        struct ad2s1200_state *st = iio_priv(indio_dev);
        int ret;

        switch (m) {
        case IIO_CHAN_INFO_SCALE:
                switch (chan->type) {
                case IIO_ANGL:
                        /* 2 * Pi / (2^12 - 1) ~= 0.001534355 */
                        *val = 0;
                        *val2 = 1534355;
                        return IIO_VAL_INT_PLUS_NANO;
                case IIO_ANGL_VEL:
                        /* 2 * Pi ~= 6.283185 */
                        *val = 6;
                        *val2 = 283185;
                        return IIO_VAL_INT_PLUS_MICRO;
                default:
                        return -EINVAL;
                }
                break;
        case IIO_CHAN_INFO_RAW:
                mutex_lock(&st->lock);
                gpiod_set_value(st->sample, 0);

                /* delay (6 * AD2S1200_TSCLK + 20) nano seconds */
                udelay(1);
                gpiod_set_value(st->sample, 1);
                gpiod_set_value(st->rdvel, !!(chan->type == IIO_ANGL));

                ret = spi_read(st->sdev, &st->rx, 2);
                if (ret < 0) {
                        mutex_unlock(&st->lock);
                        return ret;
                }

                switch (chan->type) {
                case IIO_ANGL:
                        *val = be16_to_cpup(&st->rx) >> 4;
                        break;
                case IIO_ANGL_VEL:
                        *val = sign_extend32(be16_to_cpup(&st->rx) >> 4, 11);
                        break;
                default:
                        mutex_unlock(&st->lock);
                        return -EINVAL;
                }

                /* delay (2 * AD2S1200_TSCLK + 20) ns for sample pulse */
                udelay(1);
                mutex_unlock(&st->lock);

                return IIO_VAL_INT;
        default:
                break;
        }

        return -EINVAL;
}

static const struct iio_chan_spec ad2s1200_channels[] = {
        {
                .type = IIO_ANGL,
                .indexed = 1,
                .channel = 0,
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
                .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
        }, {
                .type = IIO_ANGL_VEL,
                .indexed = 1,
                .channel = 0,
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
                .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
        }
};

static const struct iio_info ad2s1200_info = {
        .read_raw = ad2s1200_read_raw,
};

static int ad2s1200_probe(struct spi_device *spi)
{
        struct ad2s1200_state *st;
        struct iio_dev *indio_dev;
        int ret;

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

        spi_set_drvdata(spi, indio_dev);
        st = iio_priv(indio_dev);
        mutex_init(&st->lock);
        st->sdev = spi;

        st->sample = devm_gpiod_get(&spi->dev, "adi,sample", GPIOD_OUT_LOW);
        if (IS_ERR(st->sample)) {
                dev_err(&spi->dev, "Failed to claim SAMPLE gpio: err=%ld\n",
                        PTR_ERR(st->sample));
                return PTR_ERR(st->sample);
        }

        st->rdvel = devm_gpiod_get(&spi->dev, "adi,rdvel", GPIOD_OUT_LOW);
        if (IS_ERR(st->rdvel)) {
                dev_err(&spi->dev, "Failed to claim RDVEL gpio: err=%ld\n",
                        PTR_ERR(st->rdvel));
                return PTR_ERR(st->rdvel);
        }

        indio_dev->info = &ad2s1200_info;
        indio_dev->modes = INDIO_DIRECT_MODE;
        indio_dev->channels = ad2s1200_channels;
        indio_dev->num_channels = ARRAY_SIZE(ad2s1200_channels);
        indio_dev->name = spi_get_device_id(spi)->name;

        spi->max_speed_hz = AD2S1200_HZ;
        spi->mode = SPI_MODE_3;
        ret = spi_setup(spi);

        if (ret < 0) {
                dev_err(&spi->dev, "spi_setup failed!\n");
                return ret;
        }

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

static const struct of_device_id ad2s1200_of_match[] = {
        { .compatible = "adi,ad2s1200", },
        { .compatible = "adi,ad2s1205", },
        { }
};
MODULE_DEVICE_TABLE(of, ad2s1200_of_match);

static const struct spi_device_id ad2s1200_id[] = {
        { "ad2s1200" },
        { "ad2s1205" },
        { }
};
MODULE_DEVICE_TABLE(spi, ad2s1200_id);

static struct spi_driver ad2s1200_driver = {
        .driver = {
                .name = "ad2s1200",
                .of_match_table = ad2s1200_of_match,
        },
        .probe = ad2s1200_probe,
        .id_table = ad2s1200_id,
};
module_spi_driver(ad2s1200_driver);

MODULE_AUTHOR("David Veenstra <davidjulianveenstra@gmail.com>");
MODULE_AUTHOR("Graff Yang <graff.yang@gmail.com>");
MODULE_DESCRIPTION("Analog Devices AD2S1200/1205 Resolver to Digital SPI driver");
MODULE_LICENSE("GPL v2");