drivers/staging/iio/imu/adis16400_ring.c

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

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

#include "adis16400.h"

/**
 * adis16400_spi_read_burst() - read all data registers
 * @indio_dev: the IIO device
 * @rx: somewhere to pass back the value read (min size is 24 bytes)
 **/
static int adis16400_spi_read_burst(struct iio_dev *indio_dev, u8 *rx)
{
	struct spi_message msg;
	struct adis16400_state *st = iio_priv(indio_dev);
	u32 old_speed_hz = st->adis.spi->max_speed_hz;
	int ret;

	struct spi_transfer xfers[] = {
		{
			.tx_buf = st->adis.tx,
			.bits_per_word = 8,
			.len = 2,
		}, {
			.rx_buf = rx,
			.bits_per_word = 8,
			.len = 24,
		},
	};

	mutex_lock(&st->adis.txrx_lock);
	st->adis.tx[0] = ADIS_READ_REG(ADIS16400_GLOB_CMD);
	st->adis.tx[1] = 0;

	spi_message_init(&msg);
	spi_message_add_tail(&xfers[0], &msg);
	spi_message_add_tail(&xfers[1], &msg);

	st->adis.spi->max_speed_hz = min(ADIS16400_SPI_BURST, old_speed_hz);
	spi_setup(st->adis.spi);

	ret = spi_sync(st->adis.spi, &msg);
	if (ret)
		dev_err(&st->adis.spi->dev, "problem when burst reading");

	st->adis.spi->max_speed_hz = old_speed_hz;
	spi_setup(st->adis.spi);
	mutex_unlock(&st->adis.txrx_lock);
	return ret;
}

static const u16 read_all_tx_array[] = {
	cpu_to_be16(ADIS_READ_REG(ADIS16400_SUPPLY_OUT)),
	cpu_to_be16(ADIS_READ_REG(ADIS16400_XGYRO_OUT)),
	cpu_to_be16(ADIS_READ_REG(ADIS16400_YGYRO_OUT)),
	cpu_to_be16(ADIS_READ_REG(ADIS16400_ZGYRO_OUT)),
	cpu_to_be16(ADIS_READ_REG(ADIS16400_XACCL_OUT)),
	cpu_to_be16(ADIS_READ_REG(ADIS16400_YACCL_OUT)),
	cpu_to_be16(ADIS_READ_REG(ADIS16400_ZACCL_OUT)),
	cpu_to_be16(ADIS_READ_REG(ADIS16350_XTEMP_OUT)),
	cpu_to_be16(ADIS_READ_REG(ADIS16350_YTEMP_OUT)),
	cpu_to_be16(ADIS_READ_REG(ADIS16350_ZTEMP_OUT)),
	cpu_to_be16(ADIS_READ_REG(ADIS16400_AUX_ADC)),
};

static int adis16350_spi_read_all(struct iio_dev *indio_dev, u8 *rx)
{
	struct adis16400_state *st = iio_priv(indio_dev);

	struct spi_message msg;
	int i, j = 0, ret;
	struct spi_transfer *xfers;
	int scan_count = bitmap_weight(indio_dev->active_scan_mask,
				       indio_dev->masklength);

	xfers = kzalloc(sizeof(*xfers)*(scan_count + 1),
			GFP_KERNEL);
	if (xfers == NULL)
		return -ENOMEM;

	for (i = 0; i < ARRAY_SIZE(read_all_tx_array); i++)
		if (test_bit(i, indio_dev->active_scan_mask)) {
			xfers[j].tx_buf = &read_all_tx_array[i];
			xfers[j].bits_per_word = 16;
			xfers[j].len = 2;
			xfers[j + 1].rx_buf = rx + j*2;
			j++;
		}
	xfers[j].bits_per_word = 16;
	xfers[j].len = 2;

	spi_message_init(&msg);
	for (j = 0; j < scan_count + 1; j++)
		spi_message_add_tail(&xfers[j], &msg);

	ret = spi_sync(st->adis.spi, &msg);
	kfree(xfers);

	return ret;
}

/* Whilst this makes a lot of calls to iio_sw_ring functions - it is to device
 * specific to be rolled into the core.
 */
static irqreturn_t adis16400_trigger_handler(int irq, void *p)
{
	struct iio_poll_func *pf = p;
	struct iio_dev *indio_dev = pf->indio_dev;
	struct adis16400_state *st = iio_priv(indio_dev);
	int i = 0, j, ret = 0;
	s16 *data;

	/* Asumption that long is enough for maximum channels */
	unsigned long mask = *indio_dev->active_scan_mask;
	int scan_count = bitmap_weight(indio_dev->active_scan_mask,
				       indio_dev->masklength);
	data = kmalloc(indio_dev->scan_bytes, GFP_KERNEL);
	if (data == NULL) {
		dev_err(&st->adis.spi->dev, "memory alloc failed in ring bh");
		goto done;
	}

	if (scan_count) {
		if (st->variant->flags & ADIS16400_NO_BURST) {
			ret = adis16350_spi_read_all(indio_dev, st->adis.rx);
			if (ret < 0)
				goto done;
			for (; i < scan_count; i++)
				data[i]	= *(s16 *)(st->adis.rx + i*2);
		} else {
			ret = adis16400_spi_read_burst(indio_dev, st->adis.rx);
			if (ret < 0)
				goto done;
			for (; i < scan_count; i++) {
				j = __ffs(mask);
				mask &= ~(1 << j);
				data[i] = be16_to_cpup(
					(__be16 *)&(st->adis.rx[j*2]));
			}
		}
	}
	/* Guaranteed to be aligned with 8 byte boundary */
	if (indio_dev->scan_timestamp)
		*((s64 *)(data + ((i + 3)/4)*4)) = pf->timestamp;
	iio_push_to_buffers(indio_dev, (u8 *) data);

done:
	kfree(data);
	iio_trigger_notify_done(indio_dev->trig);

	return IRQ_HANDLED;
}

int adis16400_configure_ring(struct iio_dev *indio_dev)
{
	return iio_triggered_buffer_setup(indio_dev, &iio_pollfunc_store_time,
		&adis16400_trigger_handler, NULL);
}

void adis16400_unconfigure_ring(struct iio_dev *indio_dev)
{
	iio_triggered_buffer_cleanup(indio_dev);
}