diff options
| author | Lars-Peter Clausen <lars@metafoo.de> | 2019-03-19 14:37:55 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-05-31 16:47:29 +0300 |
| commit | 50892cb2923a8a410bcf0edf56c52f21c87de903 (patch) | |
| tree | 5b55f243a3551da7b07f973eca979692058bf95d /drivers/iio | |
| parent | 5163bc447add77cd7c321618b3012199480cd9b8 (diff) | |
| download | linux-50892cb2923a8a410bcf0edf56c52f21c87de903.tar.xz | |
iio: ad_sigma_delta: Properly handle SPI bus locking vs CS assertion
[ Upstream commit df1d80aee963480c5c2938c64ec0ac3e4a0df2e0 ]
For devices from the SigmaDelta family we need to keep CS low when doing a
conversion, since the device will use the MISO line as a interrupt to
indicate that the conversion is complete.
This is why the driver locks the SPI bus and when the SPI bus is locked
keeps as long as a conversion is going on. The current implementation gets
one small detail wrong though. CS is only de-asserted after the SPI bus is
unlocked. This means it is possible for a different SPI device on the same
bus to send a message which would be wrongfully be addressed to the
SigmaDelta device as well. Make sure that the last SPI transfer that is
done while holding the SPI bus lock de-asserts the CS signal.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Alexandru Ardelean <Alexandru.Ardelean@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'drivers/iio')
| -rw-r--r-- | drivers/iio/adc/ad_sigma_delta.c | 16 |
1 files changed, 11 insertions, 5 deletions
diff --git a/drivers/iio/adc/ad_sigma_delta.c b/drivers/iio/adc/ad_sigma_delta.c index a1d072ecb717..30f200ad6b97 100644 --- a/drivers/iio/adc/ad_sigma_delta.c +++ b/drivers/iio/adc/ad_sigma_delta.c @@ -62,7 +62,7 @@ int ad_sd_write_reg(struct ad_sigma_delta *sigma_delta, unsigned int reg, struct spi_transfer t = { .tx_buf = data, .len = size + 1, - .cs_change = sigma_delta->bus_locked, + .cs_change = sigma_delta->keep_cs_asserted, }; struct spi_message m; int ret; @@ -217,6 +217,7 @@ static int ad_sd_calibrate(struct ad_sigma_delta *sigma_delta, spi_bus_lock(sigma_delta->spi->master); sigma_delta->bus_locked = true; + sigma_delta->keep_cs_asserted = true; reinit_completion(&sigma_delta->completion); ret = ad_sigma_delta_set_mode(sigma_delta, mode); @@ -234,9 +235,10 @@ static int ad_sd_calibrate(struct ad_sigma_delta *sigma_delta, ret = 0; } out: + sigma_delta->keep_cs_asserted = false; + ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_IDLE); sigma_delta->bus_locked = false; spi_bus_unlock(sigma_delta->spi->master); - ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_IDLE); return ret; } @@ -288,6 +290,7 @@ int ad_sigma_delta_single_conversion(struct iio_dev *indio_dev, spi_bus_lock(sigma_delta->spi->master); sigma_delta->bus_locked = true; + sigma_delta->keep_cs_asserted = true; reinit_completion(&sigma_delta->completion); ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_SINGLE); @@ -297,9 +300,6 @@ int ad_sigma_delta_single_conversion(struct iio_dev *indio_dev, ret = wait_for_completion_interruptible_timeout( &sigma_delta->completion, HZ); - sigma_delta->bus_locked = false; - spi_bus_unlock(sigma_delta->spi->master); - if (ret == 0) ret = -EIO; if (ret < 0) @@ -315,7 +315,10 @@ out: sigma_delta->irq_dis = true; } + sigma_delta->keep_cs_asserted = false; ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_IDLE); + sigma_delta->bus_locked = false; + spi_bus_unlock(sigma_delta->spi->master); mutex_unlock(&indio_dev->mlock); if (ret) @@ -352,6 +355,8 @@ static int ad_sd_buffer_postenable(struct iio_dev *indio_dev) spi_bus_lock(sigma_delta->spi->master); sigma_delta->bus_locked = true; + sigma_delta->keep_cs_asserted = true; + ret = ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_CONTINUOUS); if (ret) goto err_unlock; @@ -380,6 +385,7 @@ static int ad_sd_buffer_postdisable(struct iio_dev *indio_dev) sigma_delta->irq_dis = true; } + sigma_delta->keep_cs_asserted = false; ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_IDLE); sigma_delta->bus_locked = false; |