ad7298_ring.c

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/*
 * AD7298 SPI ADC driver
 *
 * Copyright 2011-2012 Analog Devices Inc.
 *
 * Licensed under the GPL-2.
 */

#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 "ad7298.h"

int ad7298_update_scan_mode(struct iio_dev *indio_dev,
    const unsigned long *active_scan_mask)
{
    struct ad7298_state *st = iio_priv(indio_dev);
    int i, m;
    unsigned short command;
    int scan_count;

    /* Now compute overall size */
    scan_count = bitmap_weight(active_scan_mask, indio_dev->masklength);

    command = AD7298_WRITE | st->ext_ref;

    for (i = 0, m = AD7298_CH(0); i < AD7298_MAX_CHAN; i++, m >>= 1)
        if (test_bit(i, active_scan_mask))
            command |= m;

    st->tx_buf[0] = cpu_to_be16(command);

    /* build spi ring message */
    st->ring_xfer[0].tx_buf = &st->tx_buf[0];
    st->ring_xfer[0].len = 2;
    st->ring_xfer[0].cs_change = 1;
    st->ring_xfer[1].tx_buf = &st->tx_buf[1];
    st->ring_xfer[1].len = 2;
    st->ring_xfer[1].cs_change = 1;

    spi_message_init(&st->ring_msg);
    spi_message_add_tail(&st->ring_xfer[0], &st->ring_msg);
    spi_message_add_tail(&st->ring_xfer[1], &st->ring_msg);

    for (i = 0; i < scan_count; i++) {
        st->ring_xfer[i + 2].rx_buf = &st->rx_buf[i];
        st->ring_xfer[i + 2].len = 2;
        st->ring_xfer[i + 2].cs_change = 1;
        spi_message_add_tail(&st->ring_xfer[i + 2], &st->ring_msg);
    }
    /* make sure last transfer cs_change is not set */
    st->ring_xfer[i + 1].cs_change = 0;

    return 0;
}

static irqreturn_t ad7298_trigger_handler(int irq, void *p)
{
    struct iio_poll_func *pf = p;
    struct iio_dev *indio_dev = pf->indio_dev;
    struct ad7298_state *st = iio_priv(indio_dev);
    s64 time_ns = 0;
    __u16 buf[16];
    int b_sent, i;

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

    if (indio_dev->scan_timestamp) {
        time_ns = iio_get_time_ns();
        memcpy((u8 *)buf + indio_dev->scan_bytes - sizeof(s64),
            &time_ns, sizeof(time_ns));
    }

    for (i = 0; i < bitmap_weight(indio_dev->active_scan_mask,
                         indio_dev->masklength); i++)
        buf[i] = be16_to_cpu(st->rx_buf[i]);

    iio_push_to_buffer(indio_dev->buffer, (u8 *)buf);

done:
    iio_trigger_notify_done(indio_dev->trig);

    return IRQ_HANDLED;
}

int ad7298_register_ring_funcs_and_init(struct iio_dev *indio_dev)
{
    return iio_triggered_buffer_setup(indio_dev, NULL,
            &ad7298_trigger_handler, NULL);
}

void ad7298_ring_cleanup(struct iio_dev *indio_dev)
{
    iio_triggered_buffer_cleanup(indio_dev);
}