5.4-stable review patch. If anyone has any objections, please let me know.
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From: Guillaume Stols gstols@baylibre.com
commit 90826e08468ba7fb35d8b39645b22d9e80004afe upstream.
The current implementation attempts to recover from an eventual glitch in the clock by checking frstdata state after reading the first channel's sample: If frstdata is low, it will reset the chip and return -EIO.
This will only work in parallel mode, where frstdata pin is set low after the 2nd sample read starts.
For the serial mode, according to the datasheet, "The FRSTDATA output returns to a logic low following the 16th SCLK falling edge.", thus after the Xth pulse, X being the number of bits in a sample, the check will always be true, and the driver will not work at all in serial mode if frstdata(optional) is defined in the devicetree as it will reset the chip, and return -EIO every time read_sample is called.
Hence, this check must be removed for serial mode.
Fixes: b9618c0cacd7 ("staging: IIO: ADC: New driver for AD7606/AD7606-6/AD7606-4") Signed-off-by: Guillaume Stols gstols@baylibre.com Reviewed-by: Nuno Sa nuno.sa@analog.com Link: https://patch.msgid.link/20240702-cleanup-ad7606-v3-1-18d5ea18770e@baylibre.... Cc: Stable@vger.kernel.org Signed-off-by: Jonathan Cameron Jonathan.Cameron@huawei.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/iio/adc/ad7606.c | 28 +------------------------ drivers/iio/adc/ad7606.h | 2 + drivers/iio/adc/ad7606_par.c | 48 ++++++++++++++++++++++++++++++++++++++++--- 3 files changed, 49 insertions(+), 29 deletions(-)
--- a/drivers/iio/adc/ad7606.c +++ b/drivers/iio/adc/ad7606.c @@ -48,7 +48,7 @@ static const unsigned int ad7616_oversam 1, 2, 4, 8, 16, 32, 64, 128, };
-static int ad7606_reset(struct ad7606_state *st) +int ad7606_reset(struct ad7606_state *st) { if (st->gpio_reset) { gpiod_set_value(st->gpio_reset, 1); @@ -59,6 +59,7 @@ static int ad7606_reset(struct ad7606_st
return -ENODEV; } +EXPORT_SYMBOL_NS_GPL(ad7606_reset, IIO_AD7606);
static int ad7606_reg_access(struct iio_dev *indio_dev, unsigned int reg, @@ -87,31 +88,6 @@ static int ad7606_read_samples(struct ad { unsigned int num = st->chip_info->num_channels - 1; u16 *data = st->data; - int ret; - - /* - * The frstdata signal is set to high while and after reading the sample - * of the first channel and low for all other channels. This can be used - * to check that the incoming data is correctly aligned. During normal - * operation the data should never become unaligned, but some glitch or - * electrostatic discharge might cause an extra read or clock cycle. - * Monitoring the frstdata signal allows to recover from such failure - * situations. - */ - - if (st->gpio_frstdata) { - ret = st->bops->read_block(st->dev, 1, data); - if (ret) - return ret; - - if (!gpiod_get_value(st->gpio_frstdata)) { - ad7606_reset(st); - return -EIO; - } - - data++; - num--; - }
return st->bops->read_block(st->dev, num, data); } --- a/drivers/iio/adc/ad7606.h +++ b/drivers/iio/adc/ad7606.h @@ -153,6 +153,8 @@ int ad7606_probe(struct device *dev, int const char *name, unsigned int id, const struct ad7606_bus_ops *bops);
+int ad7606_reset(struct ad7606_state *st); + enum ad7606_supported_device_ids { ID_AD7605_4, ID_AD7606_8, --- a/drivers/iio/adc/ad7606_par.c +++ b/drivers/iio/adc/ad7606_par.c @@ -6,6 +6,7 @@ */
#include <linux/module.h> +#include <linux/gpio/consumer.h> #include <linux/platform_device.h> #include <linux/types.h> #include <linux/err.h> @@ -20,8 +21,29 @@ static int ad7606_par16_read_block(struc struct iio_dev *indio_dev = dev_get_drvdata(dev); struct ad7606_state *st = iio_priv(indio_dev);
- insw((unsigned long)st->base_address, buf, count);
+ /* + * On the parallel interface, the frstdata signal is set to high while + * and after reading the sample of the first channel and low for all + * other channels. This can be used to check that the incoming data is + * correctly aligned. During normal operation the data should never + * become unaligned, but some glitch or electrostatic discharge might + * cause an extra read or clock cycle. Monitoring the frstdata signal + * allows to recover from such failure situations. + */ + int num = count; + u16 *_buf = buf; + + if (st->gpio_frstdata) { + insw((unsigned long)st->base_address, _buf, 1); + if (!gpiod_get_value(st->gpio_frstdata)) { + ad7606_reset(st); + return -EIO; + } + _buf++; + num--; + } + insw((unsigned long)st->base_address, _buf, num); return 0; }
@@ -34,8 +56,28 @@ static int ad7606_par8_read_block(struct { struct iio_dev *indio_dev = dev_get_drvdata(dev); struct ad7606_state *st = iio_priv(indio_dev); - - insb((unsigned long)st->base_address, buf, count * 2); + /* + * On the parallel interface, the frstdata signal is set to high while + * and after reading the sample of the first channel and low for all + * other channels. This can be used to check that the incoming data is + * correctly aligned. During normal operation the data should never + * become unaligned, but some glitch or electrostatic discharge might + * cause an extra read or clock cycle. Monitoring the frstdata signal + * allows to recover from such failure situations. + */ + int num = count; + u16 *_buf = buf; + + if (st->gpio_frstdata) { + insb((unsigned long)st->base_address, _buf, 2); + if (!gpiod_get_value(st->gpio_frstdata)) { + ad7606_reset(st); + return -EIO; + } + _buf++; + num--; + } + insb((unsigned long)st->base_address, _buf, num * 2);
return 0; }