// SPDX-License-Identifier: GPL-2.0-only
/*
 * Support code for Analog Devices Sigma-Delta ADCs
 *
 * Copyright 2012 Analog Devices Inc.
 *  Author: Lars-Peter Clausen <lars@metafoo.de>
 */

#include <linux/align.h>
#include <linux/bitmap.h>
#include <linux/bitops.h>
#include <linux/cleanup.h>
#include <linux/completion.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/export.h>
#include <linux/find.h>
#include <linux/gpio/consumer.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/property.h>
#include <linux/slab.h>
#include <linux/spi/offload/consumer.h>
#include <linux/spi/spi.h>
#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/unaligned.h>

#include <linux/iio/adc/ad_sigma_delta.h>
#include <linux/iio/buffer-dmaengine.h>
#include <linux/iio/buffer.h>
#include <linux/iio/iio.h>
#include <linux/iio/trigger_consumer.h>
#include <linux/iio/trigger.h>
#include <linux/iio/triggered_buffer.h>

#define AD_SD_COMM_CHAN_MASK    0x3

#define AD_SD_REG_COMM          0x00
#define AD_SD_REG_STATUS        0x00
#define AD_SD_REG_DATA          0x03

#define AD_SD_REG_STATUS_RDY    0x80

/**
 * ad_sd_set_comm() - Set communications register
 *
 * @sigma_delta: The sigma delta device
 * @comm: New value for the communications register
 */
void ad_sd_set_comm(struct ad_sigma_delta *sigma_delta, u8 comm)
{
        /*
         * Some variants use the lower two bits of the communications register
         * to select the channel.
         */
        sigma_delta->comm = comm & AD_SD_COMM_CHAN_MASK;
}
EXPORT_SYMBOL_NS_GPL(ad_sd_set_comm, "IIO_AD_SIGMA_DELTA");

/**
 * ad_sd_write_reg() - Write a register
 *
 * @sigma_delta: The sigma delta device
 * @reg: Address of the register
 * @size: Size of the register (0-3)
 * @val: Value to write to the register
 *
 * Returns 0 on success, an error code otherwise.
 **/
int ad_sd_write_reg(struct ad_sigma_delta *sigma_delta, unsigned int reg,
        unsigned int size, unsigned int val)
{
        u8 *data = sigma_delta->tx_buf;
        struct spi_transfer t = {
                .tx_buf         = data,
                .len            = size + 1,
                .cs_change      = sigma_delta->keep_cs_asserted,
        };
        struct spi_message m;
        int ret;

        data[0] = (reg << sigma_delta->info->addr_shift) | sigma_delta->comm;

        switch (size) {
        case 3:
                put_unaligned_be24(val, &data[1]);
                break;
        case 2:
                put_unaligned_be16(val, &data[1]);
                break;
        case 1:
                data[1] = val;
                break;
        case 0:
                break;
        default:
                return -EINVAL;
        }

        spi_message_init(&m);
        spi_message_add_tail(&t, &m);

        if (sigma_delta->bus_locked)
                ret = spi_sync_locked(sigma_delta->spi, &m);
        else
                ret = spi_sync(sigma_delta->spi, &m);

        return ret;
}
EXPORT_SYMBOL_NS_GPL(ad_sd_write_reg, "IIO_AD_SIGMA_DELTA");

static void ad_sd_set_read_reg_addr(struct ad_sigma_delta *sigma_delta, u8 reg,
                                    u8 *data)
{
        data[0] = reg << sigma_delta->info->addr_shift;
        data[0] |= sigma_delta->info->read_mask;
        data[0] |= sigma_delta->comm;
}

static int ad_sd_read_reg_raw(struct ad_sigma_delta *sigma_delta,
                              unsigned int reg, unsigned int size, u8 *val)
{
        u8 *data = sigma_delta->tx_buf;
        int ret;
        struct spi_transfer t[] = {
                {
                        .tx_buf = data,
                        .len = 1,
                }, {
                        .rx_buf = val,
                        .len = size,
                        .cs_change = sigma_delta->keep_cs_asserted,
                },
        };
        struct spi_message m;

        spi_message_init(&m);

        if (sigma_delta->info->has_registers) {
                ad_sd_set_read_reg_addr(sigma_delta, reg, data);
                spi_message_add_tail(&t[0], &m);
        }
        spi_message_add_tail(&t[1], &m);

        if (sigma_delta->bus_locked)
                ret = spi_sync_locked(sigma_delta->spi, &m);
        else
                ret = spi_sync(sigma_delta->spi, &m);

        return ret;
}

/**
 * ad_sd_read_reg() - Read a register
 *
 * @sigma_delta: The sigma delta device
 * @reg: Address of the register
 * @size: Size of the register (1-4)
 * @val: Read value
 *
 * Returns 0 on success, an error code otherwise.
 **/
int ad_sd_read_reg(struct ad_sigma_delta *sigma_delta,
        unsigned int reg, unsigned int size, unsigned int *val)
{
        int ret;

        ret = ad_sd_read_reg_raw(sigma_delta, reg, size, sigma_delta->rx_buf);
        if (ret < 0)
                goto out;

        switch (size) {
        case 4:
                *val = get_unaligned_be32(sigma_delta->rx_buf);
                break;
        case 3:
                *val = get_unaligned_be24(sigma_delta->rx_buf);
                break;
        case 2:
                *val = get_unaligned_be16(sigma_delta->rx_buf);
                break;
        case 1:
                *val = sigma_delta->rx_buf[0];
                break;
        default:
                ret = -EINVAL;
                break;
        }

out:
        return ret;
}
EXPORT_SYMBOL_NS_GPL(ad_sd_read_reg, "IIO_AD_SIGMA_DELTA");

/**
 * ad_sd_reset() - Reset the serial interface
 *
 * @sigma_delta: The sigma delta device
 *
 * Returns 0 on success, an error code otherwise.
 **/
int ad_sd_reset(struct ad_sigma_delta *sigma_delta)
{
        unsigned int reset_length = sigma_delta->info->num_resetclks;
        unsigned int size;
        u8 *buf;
        int ret;

        size = BITS_TO_BYTES(reset_length);
        buf = kcalloc(size, sizeof(*buf), GFP_KERNEL);
        if (!buf)
                return -ENOMEM;

        memset(buf, 0xff, size);
        ret = spi_write(sigma_delta->spi, buf, size);
        kfree(buf);

        return ret;
}
EXPORT_SYMBOL_NS_GPL(ad_sd_reset, "IIO_AD_SIGMA_DELTA");

static bool ad_sd_disable_irq(struct ad_sigma_delta *sigma_delta)
{
        guard(spinlock_irqsave)(&sigma_delta->irq_lock);

        /* It's already off, return false to indicate nothing was changed */
        if (sigma_delta->irq_dis)
                return false;

        sigma_delta->irq_dis = true;
        disable_irq_nosync(sigma_delta->irq_line);
        return true;
}

static void ad_sd_enable_irq(struct ad_sigma_delta *sigma_delta)
{
        guard(spinlock_irqsave)(&sigma_delta->irq_lock);

        sigma_delta->irq_dis = false;
        enable_irq(sigma_delta->irq_line);
}

#define AD_SD_CLEAR_DATA_BUFLEN 9

/* Called with `sigma_delta->bus_locked == true` only. */
static int ad_sigma_delta_clear_pending_event(struct ad_sigma_delta *sigma_delta)
{
        bool pending_event;
        unsigned int data_read_len = BITS_TO_BYTES(sigma_delta->info->num_resetclks);
        u8 *data;
        struct spi_transfer t[] = {
                {
                        .len = 1,
                }, {
                        .len = data_read_len,
                }
        };
        struct spi_message m;
        int ret;

        /*
         * Read R̅D̅Y̅ pin (if possible) or status register to check if there is an
         * old event. For devices with neither an RDY GPIO nor registers,
         * ad_sd_read_reg() transmits no address byte and clocks raw MISO bytes,
         * which is indistinguishable from reading conversion data and would
         * partially consume a pending result. Skip the check for such devices.
         *
         * This is safe for all current registerless devices: ad7191 and ad7780
         * (with powerdown GPIO) are reset between conversions by CS deassertion,
         * so there is no stale result to drain; ad7780 (without powerdown GPIO)
         * and max11205 are continuously-converting and cycle ~DRDY at the output
         * data rate regardless of whether the previous result was read, so the
         * next falling edge fires naturally.
         *
         * A future registerless device that holds ~DRDY asserted until data is
         * read would be broken by this early return and would need either
         * num_resetclks set or a rdy-gpio.
         */
        if (sigma_delta->rdy_gpiod) {
                pending_event = gpiod_get_value(sigma_delta->rdy_gpiod);
        } else if (sigma_delta->info->has_registers) {
                unsigned int status_reg;

                ret = ad_sd_read_reg(sigma_delta, AD_SD_REG_STATUS, 1, &status_reg);
                if (ret)
                        return ret;

                pending_event = !(status_reg & AD_SD_REG_STATUS_RDY);
        } else {
                return 0;
        }

        if (!pending_event)
                return 0;

        /*
         * With num_resetclks = 0, data_read_len is 0 and the drain sequence
         * below would compute memset(data + 2, 0xff, 0 - 1), underflowing to
         * SIZE_MAX and corrupting the heap. There is no safe way to drain the
         * stale result without knowing the data register size; it will be
         * consumed by the first ad_sd_read_reg() call in
         * ad_sigma_delta_single_conversion().
         */
        if (!data_read_len)
                return 0;

        /*
         * In general the size of the data register is unknown. It varies from
         * device to device, might be one byte longer if CONTROL.DATA_STATUS is
         * set and even varies on some devices depending on which input is
         * selected. So send one byte to start reading the data register and
         * then just clock for some bytes with DIN (aka MOSI) high to not
         * confuse the register access state machine after the data register was
         * completely read. Note however that the sequence length must be
         * shorter than the reset procedure.
         */

        data = kzalloc(data_read_len + 1, GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        spi_message_init(&m);
        if (sigma_delta->info->has_registers) {
                unsigned int data_reg = sigma_delta->info->data_reg ?: AD_SD_REG_DATA;

                ad_sd_set_read_reg_addr(sigma_delta, data_reg, data);
                t[0].tx_buf = data;
                spi_message_add_tail(&t[0], &m);
        }

        /*
         * The first transferred byte is part of the real data register,
         * so this doesn't need to be 0xff. In the remaining
         * `data_read_len - 1` bytes are less than $num_resetclks ones.
         */
        t[1].tx_buf = data + 1;
        data[1] = 0x00;
        memset(data + 2, 0xff, data_read_len - 1);
        spi_message_add_tail(&t[1], &m);

        ret = spi_sync_locked(sigma_delta->spi, &m);

        kfree(data);

        return ret;
}

int ad_sd_calibrate(struct ad_sigma_delta *sigma_delta,
        unsigned int mode, unsigned int channel)
{
        int ret;
        unsigned long time_left;

        ret = ad_sigma_delta_set_channel(sigma_delta, channel);
        if (ret)
                return ret;

        spi_bus_lock(sigma_delta->spi->controller);
        sigma_delta->bus_locked = true;
        sigma_delta->keep_cs_asserted = true;
        reinit_completion(&sigma_delta->completion);

        ret = ad_sigma_delta_clear_pending_event(sigma_delta);
        if (ret)
                goto out;

        ret = ad_sigma_delta_set_mode(sigma_delta, mode);
        if (ret < 0)
                goto out;

        ad_sd_enable_irq(sigma_delta);
        time_left = wait_for_completion_timeout(&sigma_delta->completion, 2 * HZ);
        if (time_left == 0) {
                ad_sd_disable_irq(sigma_delta);
                ret = -EIO;
        } else {
                ret = 0;
        }
out:
        sigma_delta->keep_cs_asserted = false;
        ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_IDLE);
        ad_sigma_delta_disable_one(sigma_delta, channel);
        sigma_delta->bus_locked = false;
        spi_bus_unlock(sigma_delta->spi->controller);

        return ret;
}
EXPORT_SYMBOL_NS_GPL(ad_sd_calibrate, "IIO_AD_SIGMA_DELTA");

/**
 * ad_sd_calibrate_all() - Performs channel calibration
 * @sigma_delta: The sigma delta device
 * @cb: Array of channels and calibration type to perform
 * @n: Number of items in cb
 *
 * Returns 0 on success, an error code otherwise.
 **/
int ad_sd_calibrate_all(struct ad_sigma_delta *sigma_delta,
        const struct ad_sd_calib_data *cb, unsigned int n)
{
        unsigned int i;
        int ret;

        for (i = 0; i < n; i++) {
                ret = ad_sd_calibrate(sigma_delta, cb[i].mode, cb[i].channel);
                if (ret)
                        return ret;
        }

        return 0;
}
EXPORT_SYMBOL_NS_GPL(ad_sd_calibrate_all, "IIO_AD_SIGMA_DELTA");

/**
 * ad_sigma_delta_single_conversion() - Performs a single data conversion
 * @indio_dev: The IIO device
 * @chan: The conversion is done for this channel
 * @val: Pointer to the location where to store the read value
 *
 * Returns: 0 on success, an error value otherwise.
 */
int ad_sigma_delta_single_conversion(struct iio_dev *indio_dev,
        const struct iio_chan_spec *chan, int *val)
{
        struct ad_sigma_delta *sigma_delta = iio_device_get_drvdata(indio_dev);
        unsigned int sample, raw_sample;
        unsigned int data_reg;
        int ret = 0;

        if (!iio_device_claim_direct(indio_dev))
                return -EBUSY;

        ret = ad_sigma_delta_set_channel(sigma_delta, chan->address);
        if (ret)
                goto out_release;

        spi_bus_lock(sigma_delta->spi->controller);
        sigma_delta->bus_locked = true;
        sigma_delta->keep_cs_asserted = true;
        reinit_completion(&sigma_delta->completion);

        ret = ad_sigma_delta_clear_pending_event(sigma_delta);
        if (ret)
                goto out_unlock;

        ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_SINGLE);

        ad_sd_enable_irq(sigma_delta);
        ret = wait_for_completion_interruptible_timeout(
                        &sigma_delta->completion, HZ);

        if (ret == 0)
                ret = -EIO;
        if (ret < 0)
                goto out;

        if (sigma_delta->info->data_reg != 0)
                data_reg = sigma_delta->info->data_reg;
        else
                data_reg = AD_SD_REG_DATA;

        ret = ad_sd_read_reg(sigma_delta, data_reg,
                BITS_TO_BYTES(chan->scan_type.realbits + chan->scan_type.shift),
                &raw_sample);

out:
        ad_sd_disable_irq(sigma_delta);

out_unlock:
        sigma_delta->keep_cs_asserted = false;
        ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_IDLE);
        ad_sigma_delta_disable_one(sigma_delta, chan->address);
        sigma_delta->bus_locked = false;
        spi_bus_unlock(sigma_delta->spi->controller);
out_release:
        iio_device_release_direct(indio_dev);

        if (ret)
                return ret;

        sample = raw_sample >> chan->scan_type.shift;
        sample &= (1 << chan->scan_type.realbits) - 1;
        *val = sample;

        ret = ad_sigma_delta_postprocess_sample(sigma_delta, raw_sample);
        if (ret)
                return ret;

        return IIO_VAL_INT;
}
EXPORT_SYMBOL_NS_GPL(ad_sigma_delta_single_conversion, "IIO_AD_SIGMA_DELTA");

static int ad_sd_buffer_postenable(struct iio_dev *indio_dev)
{
        struct ad_sigma_delta *sigma_delta = iio_device_get_drvdata(indio_dev);
        const struct iio_scan_type *scan_type = &indio_dev->channels[0].scan_type;
        struct spi_transfer *xfer = sigma_delta->sample_xfer;
        unsigned int i, slot, channel;
        u8 *samples_buf;
        int ret;

        if (sigma_delta->num_slots == 1) {
                channel = find_first_bit(indio_dev->active_scan_mask,
                                         iio_get_masklength(indio_dev));
                ret = ad_sigma_delta_set_channel(sigma_delta,
                                                 indio_dev->channels[channel].address);
                if (ret)
                        return ret;
                slot = 1;
        } else {
                /*
                 * At this point update_scan_mode already enabled the required channels.
                 * For sigma-delta sequencer drivers with multiple slots, an update_scan_mode
                 * implementation is mandatory.
                 */
                slot = 0;
                iio_for_each_active_channel(indio_dev, i) {
                        sigma_delta->slots[slot] = indio_dev->channels[i].address;
                        slot++;
                }
        }

        sigma_delta->active_slots = slot;
        sigma_delta->current_slot = 0;

        if (ad_sigma_delta_has_spi_offload(sigma_delta)) {
                xfer[1].offload_flags = SPI_OFFLOAD_XFER_RX_STREAM;
                xfer[1].bits_per_word = scan_type->realbits;
                xfer[1].len = spi_bpw_to_bytes(scan_type->realbits);
        } else {
                unsigned int samples_buf_size, scan_size;

                if (sigma_delta->active_slots > 1) {
                        ret = ad_sigma_delta_append_status(sigma_delta, true);
                        if (ret)
                                return ret;
                }

                samples_buf_size =
                        ALIGN(slot * BITS_TO_BYTES(scan_type->storagebits),
                              sizeof(s64));
                samples_buf_size += sizeof(s64);
                samples_buf = devm_krealloc(&sigma_delta->spi->dev,
                                            sigma_delta->samples_buf,
                                            samples_buf_size, GFP_KERNEL);
                if (!samples_buf)
                        return -ENOMEM;

                sigma_delta->samples_buf = samples_buf;
                scan_size = BITS_TO_BYTES(scan_type->realbits + scan_type->shift);
                /* For 24-bit data, there is an extra byte of padding. */
                xfer[1].rx_buf = &sigma_delta->rx_buf[scan_size == 3 ? 1 : 0];
                xfer[1].len = scan_size + (sigma_delta->status_appended ? 1 : 0);
        }
        xfer[1].cs_change = 1;

        if (sigma_delta->info->has_registers) {
                xfer[0].tx_buf = &sigma_delta->sample_addr;
                xfer[0].len = 1;

                ad_sd_set_read_reg_addr(sigma_delta,
                                        sigma_delta->info->data_reg ?: AD_SD_REG_DATA,
                                        &sigma_delta->sample_addr);
                spi_message_init_with_transfers(&sigma_delta->sample_msg, xfer, 2);
        } else {
                spi_message_init_with_transfers(&sigma_delta->sample_msg,
                                                &xfer[1], 1);
        }

        sigma_delta->sample_msg.offload = sigma_delta->offload;

        ret = spi_optimize_message(sigma_delta->spi, &sigma_delta->sample_msg);
        if (ret)
                return ret;

        spi_bus_lock(sigma_delta->spi->controller);
        sigma_delta->bus_locked = true;
        sigma_delta->keep_cs_asserted = true;

        ret = ad_sigma_delta_clear_pending_event(sigma_delta);
        if (ret)
                goto err_unlock;

        ret = ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_CONTINUOUS);
        if (ret)
                goto err_unlock;

        if (ad_sigma_delta_has_spi_offload(sigma_delta)) {
                struct spi_offload_trigger_config config = {
                        .type = SPI_OFFLOAD_TRIGGER_DATA_READY,
                };

                ret = spi_offload_trigger_enable(sigma_delta->offload,
                                                 sigma_delta->offload_trigger,
                                                 &config);
                if (ret)
                        goto err_unlock;
        } else {
                ad_sd_enable_irq(sigma_delta);
        }

        return 0;

err_unlock:
        sigma_delta->keep_cs_asserted = false;
        ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_IDLE);
        sigma_delta->bus_locked = false;
        spi_bus_unlock(sigma_delta->spi->controller);
        spi_unoptimize_message(&sigma_delta->sample_msg);

        return ret;
}

static int ad_sd_buffer_predisable(struct iio_dev *indio_dev)
{
        struct ad_sigma_delta *sigma_delta = iio_device_get_drvdata(indio_dev);

        if (ad_sigma_delta_has_spi_offload(sigma_delta)) {
                spi_offload_trigger_disable(sigma_delta->offload,
                                            sigma_delta->offload_trigger);
        } else {
                reinit_completion(&sigma_delta->completion);
                wait_for_completion_timeout(&sigma_delta->completion, HZ);

                ad_sd_disable_irq(sigma_delta);
        }

        sigma_delta->keep_cs_asserted = false;
        ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_IDLE);

        if (sigma_delta->status_appended)
                ad_sigma_delta_append_status(sigma_delta, false);

        ad_sigma_delta_disable_all(sigma_delta);
        sigma_delta->bus_locked = false;
        spi_bus_unlock(sigma_delta->spi->controller);
        spi_unoptimize_message(&sigma_delta->sample_msg);

        return 0;
}

static irqreturn_t ad_sd_trigger_handler(int irq, void *p)
{
        struct iio_poll_func *pf = p;
        struct iio_dev *indio_dev = pf->indio_dev;
        const struct iio_scan_type *scan_type = &indio_dev->channels[0].scan_type;
        struct ad_sigma_delta *sigma_delta = iio_device_get_drvdata(indio_dev);
        u8 *data = sigma_delta->rx_buf;
        unsigned int sample_size;
        unsigned int sample_pos;
        unsigned int status_pos;
        unsigned int reg_size;
        int ret;

        reg_size = BITS_TO_BYTES(scan_type->realbits + scan_type->shift);
        /* For 24-bit data, there is an extra byte of padding. */
        status_pos = reg_size + (reg_size == 3 ? 1 : 0);

        ret = spi_sync_locked(sigma_delta->spi, &sigma_delta->sample_msg);
        if (ret)
                goto irq_handled;

        /*
         * For devices sampling only one channel at
         * once, there is no need for sample number tracking.
         */
        if (sigma_delta->active_slots == 1) {
                iio_push_to_buffers_with_timestamp(indio_dev, data, pf->timestamp);
                goto irq_handled;
        }

        if (sigma_delta->status_appended) {
                u8 converted_channel;

                converted_channel = data[status_pos] & sigma_delta->info->status_ch_mask;
                if (converted_channel != sigma_delta->slots[sigma_delta->current_slot]) {
                        /*
                         * Desync occurred during continuous sampling of multiple channels.
                         * Drop this incomplete sample and start from first channel again.
                         */

                        sigma_delta->current_slot = 0;
                        goto irq_handled;
                }
        }

        sample_size = BITS_TO_BYTES(scan_type->storagebits);
        sample_pos = sample_size * sigma_delta->current_slot;
        memcpy(&sigma_delta->samples_buf[sample_pos], data, sample_size);
        sigma_delta->current_slot++;

        if (sigma_delta->current_slot == sigma_delta->active_slots) {
                sigma_delta->current_slot = 0;
                iio_push_to_buffers_with_timestamp(indio_dev, sigma_delta->samples_buf,
                                                   pf->timestamp);
        }

irq_handled:
        iio_trigger_notify_done(indio_dev->trig);
        ad_sd_enable_irq(sigma_delta);

        return IRQ_HANDLED;
}

static bool ad_sd_validate_scan_mask(struct iio_dev *indio_dev, const unsigned long *mask)
{
        struct ad_sigma_delta *sigma_delta = iio_device_get_drvdata(indio_dev);

        return bitmap_weight(mask, iio_get_masklength(indio_dev)) <= sigma_delta->num_slots;
}

static const struct iio_buffer_setup_ops ad_sd_buffer_setup_ops = {
        .postenable = &ad_sd_buffer_postenable,
        .predisable = &ad_sd_buffer_predisable,
        .validate_scan_mask = &ad_sd_validate_scan_mask,
};

static irqreturn_t ad_sd_data_rdy_trig_poll(int irq, void *private)
{
        struct ad_sigma_delta *sigma_delta = private;

        /*
         * AD7124 and a few others use the same physical line for interrupt
         * reporting (R̅D̅Y̅) and MISO.
         * As MISO toggles when reading a register, this likely results in a
         * pending interrupt. This has two consequences: a) The irq might
         * trigger immediately after it's enabled even though the conversion
         * isn't done yet; and b) checking the STATUS register's R̅D̅Y̅ flag is
         * off-limits as reading that would trigger another irq event.
         *
         * So read the MOSI line as GPIO (if available) and only trigger the irq
         * if the line is active. Without such a GPIO assume this is a valid
         * interrupt.
         *
         * Also as disable_irq_nosync() is used to disable the irq, only act if
         * the irq wasn't disabled before.
         */
        if ((!sigma_delta->rdy_gpiod || gpiod_get_value(sigma_delta->rdy_gpiod)) &&
            ad_sd_disable_irq(sigma_delta)) {
                complete(&sigma_delta->completion);
                if (sigma_delta->trig)
                        iio_trigger_poll(sigma_delta->trig);

                return IRQ_HANDLED;
        }

        return IRQ_NONE;
}

/**
 * ad_sd_validate_trigger() - validate_trigger callback for ad_sigma_delta devices
 * @indio_dev: The IIO device
 * @trig: The new trigger
 *
 * Returns: 0 if the 'trig' matches the trigger registered by the ad_sigma_delta
 * device, -EINVAL otherwise.
 */
int ad_sd_validate_trigger(struct iio_dev *indio_dev, struct iio_trigger *trig)
{
        struct ad_sigma_delta *sigma_delta = iio_device_get_drvdata(indio_dev);

        if (sigma_delta->trig != trig)
                return -EINVAL;

        return 0;
}
EXPORT_SYMBOL_NS_GPL(ad_sd_validate_trigger, "IIO_AD_SIGMA_DELTA");

static int devm_ad_sd_probe_trigger(struct device *dev, struct iio_dev *indio_dev)
{
        struct ad_sigma_delta *sigma_delta = iio_device_get_drvdata(indio_dev);
        unsigned long irq_flags = irq_get_trigger_type(sigma_delta->irq_line);
        int ret;

        init_completion(&sigma_delta->completion);

        sigma_delta->irq_dis = true;

        /* the IRQ core clears IRQ_DISABLE_UNLAZY flag when freeing an IRQ */
        irq_set_status_flags(sigma_delta->irq_line, IRQ_DISABLE_UNLAZY);

        /* Allow overwriting the flags from firmware */
        if (!irq_flags)
                irq_flags = sigma_delta->info->irq_flags;

        ret = devm_request_irq(dev, sigma_delta->irq_line,
                               ad_sd_data_rdy_trig_poll,
                               irq_flags | IRQF_NO_AUTOEN,
                               indio_dev->name,
                               sigma_delta);
        if (ret)
                return ret;

        if (ad_sigma_delta_has_spi_offload(sigma_delta)) {
                sigma_delta->offload_trigger =
                        devm_spi_offload_trigger_get(dev, sigma_delta->offload,
                                                     SPI_OFFLOAD_TRIGGER_DATA_READY);
                if (IS_ERR(sigma_delta->offload_trigger))
                        return dev_err_probe(dev, PTR_ERR(sigma_delta->offload_trigger),
                                             "Failed to get SPI offload trigger\n");
        } else {
                if (dev != &sigma_delta->spi->dev)
                        return dev_err_probe(dev, -EFAULT,
                                "Trigger parent should be '%s', got '%s'\n",
                                dev_name(dev), dev_name(&sigma_delta->spi->dev));

                sigma_delta->trig = devm_iio_trigger_alloc(dev, "%s-dev%d",
                        indio_dev->name, iio_device_id(indio_dev));
                if (!sigma_delta->trig)
                        return -ENOMEM;

                iio_trigger_set_drvdata(sigma_delta->trig, sigma_delta);

                ret = devm_iio_trigger_register(dev, sigma_delta->trig);
                if (ret)
                        return ret;

                /* select default trigger */
                indio_dev->trig = iio_trigger_get(sigma_delta->trig);
        }

        return 0;
}

/**
 * devm_ad_sd_setup_buffer_and_trigger() - Device-managed buffer & trigger setup
 * @dev: Device object to which to bind the life-time of the resources attached
 * @indio_dev: The IIO device
 */
int devm_ad_sd_setup_buffer_and_trigger(struct device *dev, struct iio_dev *indio_dev)
{
        struct ad_sigma_delta *sigma_delta = iio_device_get_drvdata(indio_dev);
        int ret;

        sigma_delta->slots = devm_kcalloc(dev, sigma_delta->num_slots,
                                          sizeof(*sigma_delta->slots), GFP_KERNEL);
        if (!sigma_delta->slots)
                return -ENOMEM;

        if (ad_sigma_delta_has_spi_offload(sigma_delta)) {
                struct dma_chan *rx_dma;

                rx_dma = devm_spi_offload_rx_stream_request_dma_chan(dev,
                        sigma_delta->offload);
                if (IS_ERR(rx_dma))
                        return dev_err_probe(dev, PTR_ERR(rx_dma),
                                             "Failed to get RX DMA channel\n");

                ret = devm_iio_dmaengine_buffer_setup_with_handle(dev, indio_dev,
                        rx_dma, IIO_BUFFER_DIRECTION_IN);
                if (ret)
                        return dev_err_probe(dev, ret, "Cannot setup DMA buffer\n");

                indio_dev->setup_ops = &ad_sd_buffer_setup_ops;
        } else {
                ret = devm_iio_triggered_buffer_setup(dev, indio_dev,
                                                      &iio_pollfunc_store_time,
                                                      &ad_sd_trigger_handler,
                                                      &ad_sd_buffer_setup_ops);
                if (ret)
                        return ret;
        }

        return devm_ad_sd_probe_trigger(dev, indio_dev);
}
EXPORT_SYMBOL_NS_GPL(devm_ad_sd_setup_buffer_and_trigger, "IIO_AD_SIGMA_DELTA");

/**
 * ad_sd_init() - Initializes a ad_sigma_delta struct
 * @sigma_delta: The ad_sigma_delta device
 * @indio_dev: The IIO device which the Sigma Delta device is used for
 * @spi: The SPI device for the ad_sigma_delta device
 * @info: Device specific callbacks and options
 *
 * This function needs to be called before any other operations are performed on
 * the ad_sigma_delta struct.
 */
int ad_sd_init(struct ad_sigma_delta *sigma_delta, struct iio_dev *indio_dev,
        struct spi_device *spi, const struct ad_sigma_delta_info *info)
{
        sigma_delta->spi = spi;
        sigma_delta->info = info;

        /* If the field is unset in ad_sigma_delta_info, assume there can only be 1 slot. */
        if (!info->num_slots)
                sigma_delta->num_slots = 1;
        else
                sigma_delta->num_slots = info->num_slots;

        if (sigma_delta->num_slots > 1) {
                if (!indio_dev->info->update_scan_mode) {
                        dev_err(&spi->dev, "iio_dev lacks update_scan_mode().\n");
                        return -EINVAL;
                }

                if (!info->disable_all) {
                        dev_err(&spi->dev, "ad_sigma_delta_info lacks disable_all().\n");
                        return -EINVAL;
                }
        }

        spin_lock_init(&sigma_delta->irq_lock);

        if (info->has_named_irqs) {
                sigma_delta->irq_line = fwnode_irq_get_byname(dev_fwnode(&spi->dev),
                                                              "rdy");
                if (sigma_delta->irq_line < 0)
                        return dev_err_probe(&spi->dev, sigma_delta->irq_line,
                                             "Interrupt 'rdy' is required\n");
        } else {
                sigma_delta->irq_line = spi->irq;
        }

        sigma_delta->rdy_gpiod = devm_gpiod_get_optional(&spi->dev, "rdy", GPIOD_IN);
        if (IS_ERR(sigma_delta->rdy_gpiod))
                return dev_err_probe(&spi->dev, PTR_ERR(sigma_delta->rdy_gpiod),
                                     "Failed to find rdy gpio\n");

        if (sigma_delta->rdy_gpiod && !sigma_delta->irq_line) {
                sigma_delta->irq_line = gpiod_to_irq(sigma_delta->rdy_gpiod);
                if (sigma_delta->irq_line < 0)
                        return sigma_delta->irq_line;
        }

        if (info->supports_spi_offload) {
                struct spi_offload_config offload_config = {
                        .capability_flags = SPI_OFFLOAD_CAP_TRIGGER |
                                            SPI_OFFLOAD_CAP_RX_STREAM_DMA,
                };
                int ret;

                sigma_delta->offload = devm_spi_offload_get(&spi->dev, spi,
                                                            &offload_config);
                ret = PTR_ERR_OR_ZERO(sigma_delta->offload);
                if (ret && ret != -ENODEV)
                        return dev_err_probe(&spi->dev, ret, "Failed to get SPI offload\n");
        }

        iio_device_set_drvdata(indio_dev, sigma_delta);

        return 0;
}
EXPORT_SYMBOL_NS_GPL(ad_sd_init, "IIO_AD_SIGMA_DELTA");

MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
MODULE_DESCRIPTION("Analog Devices Sigma-Delta ADCs");
MODULE_LICENSE("GPL v2");
MODULE_IMPORT_NS("IIO_DMAENGINE_BUFFER");