iio: adc: ti-ads7950: allow simultaneous use of buffer and direct mode

This modifies the TI ADS7950 A/DC driver to allow the simultaneous use
of both the triggered buffer and reading channels directly (via in-
kernel API or sysfs).

The use case for this is on LEGO MINDSTORMS EV3. Two of the voltage
channels are used in-kernel by a power supply driver, which reads the
values using iio_read_channel_processed(). These channels are only read
at a slow rate (<= 1Hz).  However, we want to be able to read 12 other
channels at the same time using the triggered buffer at a high rate (>=
100Hz).

Signed-off-by: David Lechner <david@lechnology.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This commit is contained in:
David Lechner 2018-07-21 14:37:34 -05:00 коммит произвёл Jonathan Cameron
Родитель 7d7209f0c4
Коммит 8134b613b0
1 изменённых файлов: 19 добавлений и 14 удалений

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@ -68,6 +68,9 @@ struct ti_ads7950_state {
__be16 rx_buf[TI_ADS7950_MAX_CHAN + TI_ADS7950_TIMESTAMP_SIZE]
____cacheline_aligned;
__be16 tx_buf[TI_ADS7950_MAX_CHAN];
__be16 single_tx;
__be16 single_rx;
};
struct ti_ads7950_chip_info {
@ -287,18 +290,26 @@ out:
return IRQ_HANDLED;
}
static int ti_ads7950_scan_direct(struct ti_ads7950_state *st, unsigned int ch)
static int ti_ads7950_scan_direct(struct iio_dev *indio_dev, unsigned int ch)
{
struct ti_ads7950_state *st = iio_priv(indio_dev);
int ret, cmd;
mutex_lock(&indio_dev->mlock);
cmd = TI_ADS7950_CR_WRITE | TI_ADS7950_CR_CHAN(ch) | st->settings;
st->tx_buf[0] = cpu_to_be16(cmd);
st->single_tx = cpu_to_be16(cmd);
ret = spi_sync(st->spi, &st->scan_single_msg);
if (ret)
return ret;
goto out;
return be16_to_cpu(st->rx_buf[0]);
ret = be16_to_cpu(st->single_rx);
out:
mutex_unlock(&indio_dev->mlock);
return ret;
}
static int ti_ads7950_get_range(struct ti_ads7950_state *st)
@ -330,13 +341,7 @@ static int ti_ads7950_read_raw(struct iio_dev *indio_dev,
switch (m) {
case IIO_CHAN_INFO_RAW:
ret = iio_device_claim_direct_mode(indio_dev);
if (ret < 0)
return ret;
ret = ti_ads7950_scan_direct(st, chan->address);
iio_device_release_direct_mode(indio_dev);
ret = ti_ads7950_scan_direct(indio_dev, chan->address);
if (ret < 0)
return ret;
@ -402,13 +407,13 @@ static int ti_ads7950_probe(struct spi_device *spi)
* was read at the end of the first transfer.
*/
st->scan_single_xfer[0].tx_buf = &st->tx_buf[0];
st->scan_single_xfer[0].tx_buf = &st->single_tx;
st->scan_single_xfer[0].len = 2;
st->scan_single_xfer[0].cs_change = 1;
st->scan_single_xfer[1].tx_buf = &st->tx_buf[0];
st->scan_single_xfer[1].tx_buf = &st->single_tx;
st->scan_single_xfer[1].len = 2;
st->scan_single_xfer[1].cs_change = 1;
st->scan_single_xfer[2].rx_buf = &st->rx_buf[0];
st->scan_single_xfer[2].rx_buf = &st->single_rx;
st->scan_single_xfer[2].len = 2;
spi_message_init_with_transfers(&st->scan_single_msg,