// SPDX-License-Identifier: GPL-2.0
/*
 * Analog Devices AD7466/7/8 AD7476/5/7/8 (A) SPI ADC driver
 * TI ADC081S/ADC101S/ADC121S 8/10/12-bit SPI ADC driver
 *
 * Copyright 2010 Analog Devices Inc.
 */

#include <linux/bitops.h>
#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/delay.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>

struct ad7476_state;

struct ad7476_chip_info {
        unsigned int                    int_vref_mv;
        struct iio_chan_spec            channel[2];
        void (*reset)(struct ad7476_state *);
        void (*conversion_pre_op)(struct ad7476_state *st);
        void (*conversion_post_op)(struct ad7476_state *st);
        bool                            has_vref;
        bool                            has_vdrive;
        bool                            convstart_required;
};

struct ad7476_state {
        struct spi_device               *spi;
        const struct ad7476_chip_info   *chip_info;
        struct gpio_desc                *convst_gpio;
        struct spi_transfer             xfer;
        struct spi_message              msg;
        struct iio_chan_spec            channel[2];
        int                             scale_mv;
        /*
         * DMA (thus cache coherency maintenance) may require the
         * transfer buffers to live in their own cache lines.
         * Make the buffer large enough for one 16 bit sample and one 64 bit
         * aligned 64 bit timestamp.
         */
        unsigned char data[ALIGN(2, sizeof(s64)) + sizeof(s64)] __aligned(IIO_DMA_MINALIGN);
};

static void ad7091_convst(struct ad7476_state *st)
{
        if (!st->convst_gpio)
                return;

        gpiod_set_value_cansleep(st->convst_gpio, 0);
        udelay(1); /* CONVST pulse width: 10 ns min */
        gpiod_set_value_cansleep(st->convst_gpio, 1);
        udelay(1); /* Conversion time: 650 ns max */
}

static void bd79105_convst_disable(struct ad7476_state *st)
{
        gpiod_set_value_cansleep(st->convst_gpio, 0);
}

static void bd79105_convst_enable(struct ad7476_state *st)
{
        gpiod_set_value_cansleep(st->convst_gpio, 1);
        /* Worst case, 2790 ns required for conversion */
        ndelay(2790);
}

static irqreturn_t ad7476_trigger_handler(int irq, void  *p)
{
        struct iio_poll_func *pf = p;
        struct iio_dev *indio_dev = pf->indio_dev;
        struct ad7476_state *st = iio_priv(indio_dev);
        int b_sent;

        if (st->chip_info->conversion_pre_op)
                st->chip_info->conversion_pre_op(st);

        b_sent = spi_sync(st->spi, &st->msg);
        if (b_sent < 0)
                goto done;

        iio_push_to_buffers_with_ts(indio_dev, st->data, sizeof(st->data),
                                    iio_get_time_ns(indio_dev));
done:
        if (st->chip_info->conversion_post_op)
                st->chip_info->conversion_post_op(st);
        iio_trigger_notify_done(indio_dev->trig);

        return IRQ_HANDLED;
}

static void ad7091_reset(struct ad7476_state *st)
{
        /* Any transfers with 8 scl cycles will reset the device */
        spi_read(st->spi, st->data, 1);
}

static int ad7476_scan_direct(struct ad7476_state *st)
{
        int ret;

        if (st->chip_info->conversion_pre_op)
                st->chip_info->conversion_pre_op(st);

        ret = spi_sync(st->spi, &st->msg);
        if (ret)
                return ret;

        if (st->chip_info->conversion_post_op)
                st->chip_info->conversion_post_op(st);

        return be16_to_cpup((__be16 *)st->data);
}

static int ad7476_read_raw(struct iio_dev *indio_dev,
                           struct iio_chan_spec const *chan,
                           int *val,
                           int *val2,
                           long m)
{
        int ret;
        struct ad7476_state *st = iio_priv(indio_dev);

        switch (m) {
        case IIO_CHAN_INFO_RAW:
                if (!iio_device_claim_direct(indio_dev))
                        return -EBUSY;
                ret = ad7476_scan_direct(st);
                iio_device_release_direct(indio_dev);

                if (ret < 0)
                        return ret;
                *val = (ret >> chan->scan_type.shift) &
                        GENMASK(chan->scan_type.realbits - 1, 0);
                return IIO_VAL_INT;
        case IIO_CHAN_INFO_SCALE:
                *val = st->scale_mv;
                *val2 = chan->scan_type.realbits;
                return IIO_VAL_FRACTIONAL_LOG2;
        }
        return -EINVAL;
}

#define _AD7476_CHAN(bits, _shift, _info_mask_sep)              \
        {                                                       \
        .type = IIO_VOLTAGE,                                    \
        .indexed = 1,                                           \
        .info_mask_separate = _info_mask_sep,                   \
        .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
        .scan_type = {                                          \
                .sign = 'u',                                    \
                .realbits = (bits),                             \
                .storagebits = 16,                              \
                .shift = (_shift),                              \
                .endianness = IIO_BE,                           \
        },                                                      \
}

#define ADC081S_CHAN(bits) _AD7476_CHAN((bits), 12 - (bits), \
                BIT(IIO_CHAN_INFO_RAW))
#define AD7476_CHAN(bits) _AD7476_CHAN((bits), 13 - (bits), \
                BIT(IIO_CHAN_INFO_RAW))
#define AD7940_CHAN(bits) _AD7476_CHAN((bits), 15 - (bits), \
                BIT(IIO_CHAN_INFO_RAW))
#define AD7091R_CHAN(bits) _AD7476_CHAN((bits), 16 - (bits), 0)
#define ADS786X_CHAN(bits) _AD7476_CHAN((bits), 12 - (bits), \
                BIT(IIO_CHAN_INFO_RAW))

static const struct ad7476_chip_info ad7091_chip_info = {
        .channel[0] = AD7091R_CHAN(12),
        .channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
        .conversion_pre_op = ad7091_convst,
        .reset = ad7091_reset,
};

static const struct ad7476_chip_info ad7091r_chip_info = {
        .channel[0] = AD7091R_CHAN(12),
        .channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
        .conversion_pre_op = ad7091_convst,
        .int_vref_mv = 2500,
        .has_vref = true,
        .reset = ad7091_reset,
};

static const struct ad7476_chip_info ad7273_chip_info = {
        .channel[0] = AD7940_CHAN(10),
        .channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
        .has_vref = true,
};

static const struct ad7476_chip_info ad7274_chip_info = {
        .channel[0] = AD7940_CHAN(12),
        .channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
        .has_vref = true,
};

static const struct ad7476_chip_info ad7276_chip_info = {
        .channel[0] = AD7940_CHAN(12),
        .channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
};

static const struct ad7476_chip_info ad7277_chip_info = {
        .channel[0] = AD7940_CHAN(10),
        .channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
};

static const struct ad7476_chip_info ad7278_chip_info = {
        .channel[0] = AD7940_CHAN(8),
        .channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
};

static const struct ad7476_chip_info ad7466_chip_info = {
        .channel[0] = AD7476_CHAN(12),
        .channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
};

static const struct ad7476_chip_info ad7467_chip_info = {
        .channel[0] = AD7476_CHAN(10),
        .channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
};

static const struct ad7476_chip_info ad7468_chip_info = {
        .channel[0] = AD7476_CHAN(8),
        .channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
};

static const struct ad7476_chip_info ad7475_chip_info = {
        .channel[0] = AD7476_CHAN(12),
        .channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
        .has_vref = true,
        .has_vdrive = true,
};

static const struct ad7476_chip_info ad7495_chip_info = {
        .channel[0] = AD7476_CHAN(12),
        .channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
        .int_vref_mv = 2500,
        .has_vdrive = true,
};

static const struct ad7476_chip_info ad7940_chip_info = {
        .channel[0] = AD7940_CHAN(14),
        .channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
};

static const struct ad7476_chip_info adc081s_chip_info = {
        .channel[0] = ADC081S_CHAN(8),
        .channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
};

static const struct ad7476_chip_info adc101s_chip_info = {
        .channel[0] = ADC081S_CHAN(10),
        .channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
};

static const struct ad7476_chip_info adc121s_chip_info = {
        .channel[0] = ADC081S_CHAN(12),
        .channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
};

static const struct ad7476_chip_info ads7866_chip_info = {
        .channel[0] = ADS786X_CHAN(12),
        .channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
};

static const struct ad7476_chip_info ads7867_chip_info = {
        .channel[0] = ADS786X_CHAN(10),
        .channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
};

static const struct ad7476_chip_info ads7868_chip_info = {
        .channel[0] = ADS786X_CHAN(8),
        .channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
};

static const struct ad7476_chip_info ltc2314_14_chip_info = {
        .channel[0] = AD7940_CHAN(14),
        .channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
        .has_vref = true,
};

static const struct ad7476_chip_info bd79105_chip_info = {
        .channel[0] = AD7091R_CHAN(16),
        .channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
        /*
         * The BD79105 starts ADC data conversion when the CONVSTART line is
         * set HIGH. The CONVSTART must be kept HIGH until the data has been
         * read from the ADC.
         */
        .conversion_pre_op = bd79105_convst_enable,
        .conversion_post_op = bd79105_convst_disable,
        /* BD79105 won't do conversion without convstart */
        .convstart_required = true,
        .has_vref = true,
        .has_vdrive = true,
};

static const struct iio_info ad7476_info = {
        .read_raw = &ad7476_read_raw,
};

static int ad7476_probe(struct spi_device *spi)
{
        struct ad7476_state *st;
        struct iio_dev *indio_dev;
        unsigned int i;
        int ret;

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

        st = iio_priv(indio_dev);

        st->chip_info = spi_get_device_match_data(spi);
        if (!st->chip_info)
                return -ENODEV;

        /* Use VCC for reference voltage if vref / internal vref aren't used */
        if (!st->chip_info->int_vref_mv && !st->chip_info->has_vref) {
                ret = devm_regulator_get_enable_read_voltage(&spi->dev, "vcc");
                if (ret < 0)
                        return ret;
                st->scale_mv = ret / 1000;
        } else {
                ret = devm_regulator_get_enable(&spi->dev, "vcc");
                if (ret < 0)
                        return ret;
        }

        if (st->chip_info->has_vref) {
                ret = devm_regulator_get_enable_read_voltage(&spi->dev, "vref");
                if (ret < 0) {
                        /* Vref is optional if a device has an internal reference */
                        if (!st->chip_info->int_vref_mv || ret != -ENODEV)
                                return ret;
                } else {
                        st->scale_mv = ret / 1000;
                }
        }

        if (!st->scale_mv)
                st->scale_mv = st->chip_info->int_vref_mv;

        if (st->chip_info->has_vdrive) {
                ret = devm_regulator_get_enable(&spi->dev, "vdrive");
                if (ret)
                        return ret;
        }

        st->convst_gpio = devm_gpiod_get_optional(&spi->dev,
                                                  "adi,conversion-start",
                                                  GPIOD_OUT_LOW);
        if (IS_ERR(st->convst_gpio))
                return PTR_ERR(st->convst_gpio);

        if (st->chip_info->convstart_required && !st->convst_gpio)
                return dev_err_probe(&spi->dev, -EINVAL, "No convstart GPIO\n");

        /*
         * This will never happen. Unless someone changes the channel specs
         * in this driver. And if someone does, without changing the loop
         * below, then we'd better immediately produce a big fat error, before
         * the change proceeds from that developer's table.
         */
        static_assert(ARRAY_SIZE(st->channel) == ARRAY_SIZE(st->chip_info->channel));
        for (i = 0; i < ARRAY_SIZE(st->channel); i++) {
                st->channel[i] = st->chip_info->channel[i];
                if (st->convst_gpio)
                        __set_bit(IIO_CHAN_INFO_RAW,
                                  &st->channel[i].info_mask_separate);
        }

        st->spi = spi;

        indio_dev->name = spi_get_device_id(spi)->name;
        indio_dev->modes = INDIO_DIRECT_MODE;
        indio_dev->channels = st->channel;
        indio_dev->num_channels = ARRAY_SIZE(st->channel);
        indio_dev->info = &ad7476_info;

        /* Setup default message */

        st->xfer.rx_buf = &st->data;
        st->xfer.len = indio_dev->channels[0].scan_type.storagebits / 8;

        spi_message_init(&st->msg);
        spi_message_add_tail(&st->xfer, &st->msg);

        ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev, NULL,
                                              &ad7476_trigger_handler, NULL);
        if (ret)
                return ret;

        if (st->chip_info->reset)
                st->chip_info->reset(st);

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

static const struct spi_device_id ad7476_id[] = {
        { "ad7091", (kernel_ulong_t)&ad7091_chip_info },
        { "ad7091r", (kernel_ulong_t)&ad7091r_chip_info },
        { "ad7273", (kernel_ulong_t)&ad7273_chip_info },
        { "ad7274", (kernel_ulong_t)&ad7274_chip_info },
        { "ad7276", (kernel_ulong_t)&ad7276_chip_info },
        { "ad7277", (kernel_ulong_t)&ad7277_chip_info },
        { "ad7278", (kernel_ulong_t)&ad7278_chip_info },
        { "ad7466", (kernel_ulong_t)&ad7466_chip_info },
        { "ad7467", (kernel_ulong_t)&ad7467_chip_info },
        { "ad7468", (kernel_ulong_t)&ad7468_chip_info },
        { "ad7475", (kernel_ulong_t)&ad7475_chip_info },
        { "ad7476", (kernel_ulong_t)&ad7466_chip_info },
        { "ad7476a", (kernel_ulong_t)&ad7466_chip_info },
        { "ad7477", (kernel_ulong_t)&ad7467_chip_info },
        { "ad7477a", (kernel_ulong_t)&ad7467_chip_info },
        { "ad7478", (kernel_ulong_t)&ad7468_chip_info },
        { "ad7478a", (kernel_ulong_t)&ad7468_chip_info },
        { "ad7495", (kernel_ulong_t)&ad7495_chip_info },
        { "ad7910", (kernel_ulong_t)&ad7467_chip_info },
        { "ad7920", (kernel_ulong_t)&ad7466_chip_info },
        { "ad7940", (kernel_ulong_t)&ad7940_chip_info },
        { "adc081s", (kernel_ulong_t)&adc081s_chip_info },
        { "adc101s", (kernel_ulong_t)&adc101s_chip_info },
        { "adc121s", (kernel_ulong_t)&adc121s_chip_info },
        { "ads7866", (kernel_ulong_t)&ads7866_chip_info },
        { "ads7867", (kernel_ulong_t)&ads7867_chip_info },
        { "ads7868", (kernel_ulong_t)&ads7868_chip_info },
        { "bd79105", (kernel_ulong_t)&bd79105_chip_info },
        /*
         * The ROHM BU79100G is identical to the TI's ADS7866 from the software
         * point of view. The binding document mandates the ADS7866 to be
         * marked as a fallback for the BU79100G, but we still need the SPI ID
         * here to make the module loading work.
         */
        { "bu79100g", (kernel_ulong_t)&ads7866_chip_info },
        { "ltc2314-14", (kernel_ulong_t)&ltc2314_14_chip_info },
        { }
};
MODULE_DEVICE_TABLE(spi, ad7476_id);

static struct spi_driver ad7476_driver = {
        .driver = {
                .name   = "ad7476",
        },
        .probe          = ad7476_probe,
        .id_table       = ad7476_id,
};
module_spi_driver(ad7476_driver);

MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
MODULE_DESCRIPTION("Analog Devices AD7476 and similar 1-channel ADCs");
MODULE_LICENSE("GPL v2");