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) without breaking the power supply driver.
Signed-off-by: David Lechner <david@xxxxxxxxxxxxxx>
---
drivers/iio/adc/ti-ads7950.c | 29 +++++++++++++++++------------
1 file changed, 17 insertions(+), 12 deletions(-)
diff --git a/drivers/iio/adc/ti-ads7950.c b/drivers/iio/adc/ti-ads7950.c
index 0225c1b333ab..ba7e5a027490 100644
--- a/drivers/iio/adc/ti-ads7950.c
+++ b/drivers/iio/adc/ti-ads7950.c
@@ -58,6 +58,7 @@
(((val) >> (dec)) & ((1 << (bits)) - 1))
struct ti_ads7950_state {
+ struct iio_dev *indio_dev;
struct spi_device *spi;
struct spi_transfer ring_xfer[TI_ADS7950_MAX_CHAN + 2];
struct spi_transfer scan_single_xfer[3];
@@ -68,6 +69,8 @@ struct ti_ads7950_state {
unsigned int vref_mv;
unsigned int settings;
+ __be16 single_tx;
+ __be16 single_rx;
/*
* DMA (thus cache coherency maintenance) requires the
@@ -299,14 +302,21 @@ static int ti_ads7950_scan_direct(struct ti_ads7950_state *st, unsigned int ch)
{
int ret, cmd;
+ mutex_lock(&st->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;
+
+ ret = be16_to_cpu(st->single_rx);
+
+out:
+ mutex_unlock(&st->indio_dev->mlock);
- return be16_to_cpu(st->rx_buf[0]);
+ return ret;
}
static int ti_ads7950_get_range(struct ti_ads7950_state *st)
@@ -338,13 +348,7 @@ 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);
if (ret < 0)
return ret;
@@ -389,6 +393,7 @@ static int ti_ads7950_probe(struct spi_device *spi)
spi_set_drvdata(spi, indio_dev);
+ st->indio_dev = indio_dev;
st->spi = spi;
st->settings = TI_ADS7950_CR_MANUAL | TI_ADS7950_CR_RANGE_5V;
@@ -410,13 +415,13 @@ 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,
--
2.17.1
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