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authorLars-Peter Clausen <lars@metafoo.de>2019-03-19 13:37:55 +0200
committerJonathan Cameron <Jonathan.Cameron@huawei.com>2019-04-04 20:21:15 +0100
commitdf1d80aee963480c5c2938c64ec0ac3e4a0df2e0 (patch)
tree7a71da35da3a7573ae4e08a510ab7c8838c8f5f2 /drivers/iio
parent6ec417d2f1a028705a1ae6f59d3e15344f6a4fbe (diff)
downloadlinux-df1d80aee963480c5c2938c64ec0ac3e4a0df2e0.tar.gz
iio: ad_sigma_delta: Properly handle SPI bus locking vs CS assertion
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>
Diffstat (limited to 'drivers/iio')
-rw-r--r--drivers/iio/adc/ad_sigma_delta.c16
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 ff5f2da2e1b1..af6cbc683214 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;
}
@@ -289,6 +291,7 @@ 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);
@@ -298,9 +301,6 @@ 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)
@@ -321,7 +321,10 @@ 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)
@@ -358,6 +361,8 @@ 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;
@@ -386,6 +391,7 @@ 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;