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* AD7298 SPI ADC driver
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* Copyright 2011 Analog Devices Inc.
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* Licensed under the GPL-2.
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#include <linux/interrupt.h>
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include <linux/spi/spi.h>
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#include "../buffer_generic.h"
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#include "../ring_sw.h"
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#include "../trigger_consumer.h"
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int ad7298_scan_from_ring(struct iio_dev *indio_dev, long ch)
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struct iio_buffer *ring = indio_dev->buffer;
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if (!(test_bit(ch, ring->scan_mask))) {
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ring_data = kmalloc(ring->access->get_bytes_per_datum(ring),
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if (ring_data == NULL) {
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ret = ring->access->read_last(ring, (u8 *) ring_data);
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goto error_free_ring_data;
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ret = be16_to_cpu(ring_data[ch]);
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* ad7298_ring_preenable() setup the parameters of the ring before enabling
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* The complex nature of the setting of the number of bytes per datum is due
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* to this driver currently ensuring that the timestamp is stored at an 8
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static int ad7298_ring_preenable(struct iio_dev *indio_dev)
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struct ad7298_state *st = iio_priv(indio_dev);
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struct iio_buffer *ring = indio_dev->buffer;
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unsigned short command;
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d_size = ring->scan_count * (AD7298_STORAGE_BITS / 8);
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if (ring->scan_timestamp) {
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d_size += sizeof(s64);
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if (d_size % sizeof(s64))
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d_size += sizeof(s64) - (d_size % sizeof(s64));
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if (ring->access->set_bytes_per_datum)
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ring->access->set_bytes_per_datum(ring, d_size);
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command = AD7298_WRITE | st->ext_ref;
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for (i = 0, m = AD7298_CH(0); i < AD7298_MAX_CHAN; i++, m >>= 1)
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if (test_bit(i, ring->scan_mask))
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st->tx_buf[0] = cpu_to_be16(command);
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/* build spi ring message */
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st->ring_xfer[0].tx_buf = &st->tx_buf[0];
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st->ring_xfer[0].len = 2;
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st->ring_xfer[0].cs_change = 1;
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st->ring_xfer[1].tx_buf = &st->tx_buf[1];
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st->ring_xfer[1].len = 2;
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st->ring_xfer[1].cs_change = 1;
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spi_message_init(&st->ring_msg);
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spi_message_add_tail(&st->ring_xfer[0], &st->ring_msg);
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spi_message_add_tail(&st->ring_xfer[1], &st->ring_msg);
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for (i = 0; i < ring->scan_count; i++) {
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st->ring_xfer[i + 2].rx_buf = &st->rx_buf[i];
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st->ring_xfer[i + 2].len = 2;
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st->ring_xfer[i + 2].cs_change = 1;
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spi_message_add_tail(&st->ring_xfer[i + 2], &st->ring_msg);
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/* make sure last transfer cs_change is not set */
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st->ring_xfer[i + 1].cs_change = 0;
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* ad7298_trigger_handler() bh of trigger launched polling to ring buffer
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* Currently there is no option in this driver to disable the saving of
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* timestamps within the ring.
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static irqreturn_t ad7298_trigger_handler(int irq, void *p)
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struct iio_poll_func *pf = p;
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struct iio_dev *indio_dev = pf->indio_dev;
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struct ad7298_state *st = iio_priv(indio_dev);
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struct iio_buffer *ring = indio_dev->buffer;
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b_sent = spi_sync(st->spi, &st->ring_msg);
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if (ring->scan_timestamp) {
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time_ns = iio_get_time_ns();
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memcpy((u8 *)buf + st->d_size - sizeof(s64),
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&time_ns, sizeof(time_ns));
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for (i = 0; i < ring->scan_count; i++)
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buf[i] = be16_to_cpu(st->rx_buf[i]);
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indio_dev->buffer->access->store_to(ring, (u8 *)buf, time_ns);
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iio_trigger_notify_done(indio_dev->trig);
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static const struct iio_buffer_setup_ops ad7298_ring_setup_ops = {
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.preenable = &ad7298_ring_preenable,
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.postenable = &iio_triggered_buffer_postenable,
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.predisable = &iio_triggered_buffer_predisable,
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int ad7298_register_ring_funcs_and_init(struct iio_dev *indio_dev)
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indio_dev->buffer = iio_sw_rb_allocate(indio_dev);
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if (!indio_dev->buffer) {
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/* Effectively select the ring buffer implementation */
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indio_dev->buffer->access = &ring_sw_access_funcs;
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indio_dev->pollfunc = iio_alloc_pollfunc(NULL,
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&ad7298_trigger_handler,
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if (indio_dev->pollfunc == NULL) {
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goto error_deallocate_sw_rb;
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/* Ring buffer functions - here trigger setup related */
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indio_dev->buffer->setup_ops = &ad7298_ring_setup_ops;
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indio_dev->buffer->scan_timestamp = true;
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/* Flag that polled ring buffering is possible */
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indio_dev->modes |= INDIO_BUFFER_TRIGGERED;
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error_deallocate_sw_rb:
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iio_sw_rb_free(indio_dev->buffer);
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void ad7298_ring_cleanup(struct iio_dev *indio_dev)
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iio_dealloc_pollfunc(indio_dev->pollfunc);
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iio_sw_rb_free(indio_dev->buffer);