// SPDX-License-Identifier: GPL-2.0-only
/*
 * ltc2496.c - Driver for Analog Devices/Linear Technology LTC2496 ADC
 *
 * Based on ltc2497.c which has
 * Copyright (C) 2017 Analog Devices Inc.
 *
 * Licensed under the GPL-2.
 *
 * Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/2496fc.pdf
 */

#include <linux/spi/spi.h>
#include <linux/iio/iio.h>
#include <linux/iio/driver.h>
#include <linux/module.h>
#include <linux/property.h>

#include "ltc2497.h"

struct ltc2496_driverdata {
        /* this must be the first member */
        struct ltc2497core_driverdata common_ddata;
        struct spi_device *spi;

        /*
         * DMA (thus cache coherency maintenance) may require the
         * transfer buffers to live in their own cache lines.
         */
        unsigned char rxbuf[3] __aligned(IIO_DMA_MINALIGN);
        unsigned char txbuf[3];
};

static int ltc2496_result_and_measure(struct ltc2497core_driverdata *ddata,
                                      u8 address, int *val)
{
        struct ltc2496_driverdata *st =
                container_of(ddata, struct ltc2496_driverdata, common_ddata);
        struct spi_transfer t = {
                .tx_buf = st->txbuf,
                .rx_buf = st->rxbuf,
                .len = sizeof(st->txbuf),
        };
        int ret;

        st->txbuf[0] = LTC2497_ENABLE | address;

        ret = spi_sync_transfer(st->spi, &t, 1);
        if (ret < 0)  {
                dev_err(&st->spi->dev, "spi_sync_transfer failed: %pe\n",
                        ERR_PTR(ret));
                return ret;
        }

        if (val)
                *val = ((st->rxbuf[0] & 0x3f) << 12 |
                        st->rxbuf[1] << 4 | st->rxbuf[2] >> 4) -
                        (1 << 17);

        return 0;
}

static int ltc2496_probe(struct spi_device *spi)
{
        struct iio_dev *indio_dev;
        struct ltc2496_driverdata *st;
        struct device *dev = &spi->dev;

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

        st = iio_priv(indio_dev);
        spi_set_drvdata(spi, indio_dev);
        st->spi = spi;
        st->common_ddata.result_and_measure = ltc2496_result_and_measure;
        st->common_ddata.chip_info = device_get_match_data(dev);

        return ltc2497core_probe(dev, indio_dev);
}

static void ltc2496_remove(struct spi_device *spi)
{
        struct iio_dev *indio_dev = spi_get_drvdata(spi);

        ltc2497core_remove(indio_dev);
}

static const struct ltc2497_chip_info ltc2496_info = {
        .resolution = 16,
        .name = NULL,
};

static const struct of_device_id ltc2496_of_match[] = {
        { .compatible = "lltc,ltc2496", .data = &ltc2496_info, },
        { }
};
MODULE_DEVICE_TABLE(of, ltc2496_of_match);

static struct spi_driver ltc2496_driver = {
        .driver = {
                .name = "ltc2496",
                .of_match_table = ltc2496_of_match,
        },
        .probe = ltc2496_probe,
        .remove = ltc2496_remove,
};
module_spi_driver(ltc2496_driver);

MODULE_AUTHOR("Uwe Kleine-König <u.kleine-könig@pengutronix.de>");
MODULE_DESCRIPTION("Linear Technology LTC2496 ADC driver");
MODULE_LICENSE("GPL v2");