ad7887_ring.c

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/*
 * Copyright 2010-2012 Analog Devices Inc.
 * Copyright (C) 2008 Jonathan Cameron
 *
 * Licensed under the GPL-2.
 *
 * ad7887_ring.c
 */

#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/spi/spi.h>

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

#include "ad7887.h"

static int ad7887_ring_preenable(struct iio_dev *indio_dev)
{
    struct ad7887_state *st = iio_priv(indio_dev);
    int ret;

    ret = iio_sw_buffer_preenable(indio_dev);
    if (ret < 0)
        return ret;

    /* We know this is a single long so can 'cheat' */
    switch (*indio_dev->active_scan_mask) {
    case (1 << 0):
        st->ring_msg = &st->msg[AD7887_CH0];
        break;
    case (1 << 1):
        st->ring_msg = &st->msg[AD7887_CH1];
        /* Dummy read: push CH1 setting down to hardware */
        spi_sync(st->spi, st->ring_msg);
        break;
    case ((1 << 1) | (1 << 0)):
        st->ring_msg = &st->msg[AD7887_CH0_CH1];
        break;
    }

    return 0;
}

static int ad7887_ring_postdisable(struct iio_dev *indio_dev)
{
    struct ad7887_state *st = iio_priv(indio_dev);

    /* dummy read: restore default CH0 settin */
    return spi_sync(st->spi, &st->msg[AD7887_CH0]);
}

static irqreturn_t ad7887_trigger_handler(int irq, void *p)
{
    struct iio_poll_func *pf = p;
    struct iio_dev *indio_dev = pf->indio_dev;
    struct ad7887_state *st = iio_priv(indio_dev);
    s64 time_ns;
    __u8 *buf;
    int b_sent;

    unsigned int bytes = bitmap_weight(indio_dev->active_scan_mask,
                       indio_dev->masklength) *
        st->chip_info->channel[0].scan_type.storagebits / 8;

    buf = kzalloc(indio_dev->scan_bytes, GFP_KERNEL);
    if (buf == NULL)
        goto done;

    b_sent = spi_sync(st->spi, st->ring_msg);
    if (b_sent)
        goto done;

    time_ns = iio_get_time_ns();

    memcpy(buf, st->data, bytes);
    if (indio_dev->scan_timestamp)
        memcpy(buf + indio_dev->scan_bytes - sizeof(s64),
               &time_ns, sizeof(time_ns));

    iio_push_to_buffer(indio_dev->buffer, buf);
done:
    kfree(buf);
    iio_trigger_notify_done(indio_dev->trig);

    return IRQ_HANDLED;
}

static const struct iio_buffer_setup_ops ad7887_ring_setup_ops = {
    .preenable = &ad7887_ring_preenable,
    .postenable = &iio_triggered_buffer_postenable,
    .predisable = &iio_triggered_buffer_predisable,
    .postdisable = &ad7887_ring_postdisable,
};

int ad7887_register_ring_funcs_and_init(struct iio_dev *indio_dev)
{
    return iio_triggered_buffer_setup(indio_dev, &iio_pollfunc_store_time,
            &ad7887_trigger_handler, &ad7887_ring_setup_ops);
}

void ad7887_ring_cleanup(struct iio_dev *indio_dev)
{
    iio_triggered_buffer_cleanup(indio_dev);
}