[ 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 --- drivers/iio/adc/ad_sigma_delta.c | 16 +++++++++++----- include/linux/iio/adc/ad_sigma_delta.h | 1 + 2 files changed, 12 insertions(+), 5 deletions(-)
diff --git a/drivers/iio/adc/ad_sigma_delta.c b/drivers/iio/adc/ad_sigma_delta.c index a1d072ecb7171..30f200ad6b978 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 @@ int ad_sigma_delta_single_conversion(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; + 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; diff --git a/include/linux/iio/adc/ad_sigma_delta.h b/include/linux/iio/adc/ad_sigma_delta.h index 1fc7abd28b0b0..7b7157c26d313 100644 --- a/include/linux/iio/adc/ad_sigma_delta.h +++ b/include/linux/iio/adc/ad_sigma_delta.h @@ -66,6 +66,7 @@ struct ad_sigma_delta { bool irq_dis;
bool bus_locked; + bool keep_cs_asserted;
uint8_t comm;