// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2011 Jonathan Cameron
 *
 * Buffer handling elements of industrial I/O reference driver.
 * Uses the kfifo buffer.
 *
 * To test without hardware use the sysfs trigger.
 */

#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/bitmap.h>

#include <linux/iio/iio.h>
#include <linux/iio/buffer.h>
#include <linux/iio/trigger_consumer.h>
#include <linux/iio/triggered_buffer.h>

#include "iio_simple_dummy.h"

/* Some fake data */

static const s16 fakedata[] = {
        [DUMMY_INDEX_VOLTAGE_0] = 7,
        [DUMMY_INDEX_DIFFVOLTAGE_1M2] = -33,
        [DUMMY_INDEX_DIFFVOLTAGE_3M4] = -2,
        [DUMMY_INDEX_ACCELX] = 344,
};

struct dummy_scan {
        s16 data[ARRAY_SIZE(fakedata)];
        aligned_s64 timestamp;
};

/**
 * iio_simple_dummy_trigger_h() - the trigger handler function
 * @irq: the interrupt number
 * @p: private data - always a pointer to the poll func.
 *
 * This is the guts of buffered capture. On a trigger event occurring,
 * if the pollfunc is attached then this handler is called as a threaded
 * interrupt (and hence may sleep). It is responsible for grabbing data
 * from the device and pushing it into the associated buffer.
 */
static irqreturn_t iio_simple_dummy_trigger_h(int irq, void *p)
{
        struct iio_poll_func *pf = p;
        struct iio_dev *indio_dev = pf->indio_dev;
        struct dummy_scan *scan;
        int i = 0, j;

        /*
         * Note that some buses such as SPI require DMA safe buffers which
         * cannot be on the stack. Two easy ways to do this:
         *  - Local kzalloc (as done here)
         *  - A buffer at the end of the structure accessed via iio_priv()
         *    that is marked __aligned(IIO_DMA_MINALIGN).
         */
        scan = kzalloc_obj(*scan);
        if (!scan)
                goto done;

        /*
         * Three common options here:
         * hardware scans:
         *   certain combinations of channels make up a fast read. The capture
         *   will consist of all of them. Hence we just call the grab data
         *   function and fill the buffer without processing.
         * software scans:
         *   can be considered to be random access so efficient reading is just
         *   a case of minimal bus transactions.
         * software culled hardware scans:
         *   occasionally a driver may process the nearest hardware scan to avoid
         *   storing elements that are not desired. This is the fiddliest option
         *   by far.
         * Here let's pretend we have random access. And the values are in the
         * constant table fakedata.
         */
        iio_for_each_active_channel(indio_dev, j)
                scan->data[i++] = fakedata[j];

        iio_push_to_buffers_with_ts(indio_dev, scan, sizeof(*scan),
                                    iio_get_time_ns(indio_dev));

        kfree(scan);
done:
        /*
         * Tell the core we are done with this trigger and ready for the
         * next one.
         */
        iio_trigger_notify_done(indio_dev->trig);

        return IRQ_HANDLED;
}

static const struct iio_buffer_setup_ops iio_simple_dummy_buffer_setup_ops = {
};

int iio_simple_dummy_configure_buffer(struct iio_dev *indio_dev)
{
        return iio_triggered_buffer_setup(indio_dev, NULL,
                                          iio_simple_dummy_trigger_h,
                                          &iio_simple_dummy_buffer_setup_ops);
}

/**
 * iio_simple_dummy_unconfigure_buffer() - release buffer resources
 * @indio_dev: device instance state
 */
void iio_simple_dummy_unconfigure_buffer(struct iio_dev *indio_dev)
{
        iio_triggered_buffer_cleanup(indio_dev);
}