iio: adc: ad7091r: Allow users to configure device events

AD7091R-5 devices are supported by the ad7091r-5 driver together with
the ad7091r-base driver. Those drivers declared iio events for notifying
user space when ADC readings fall bellow the thresholds of low limit
registers or above the values set in high limit registers.
However, to configure iio events and their thresholds, a set of callback
functions must be implemented and those were not present until now.
The consequence of trying to configure ad7091r-5 events without the
proper callback functions was a null pointer dereference in the kernel
because the pointers to the callback functions were not set.

Implement event configuration callbacks allowing users to read/write
event thresholds and enable/disable event generation.

Since the event spec structs are generic to AD7091R devices, also move
those from the ad7091r-5 driver the base driver so they can be reused
when support for ad7091r-2/-4/-8 be added.

Fixes: ca69300173b6 ("iio: adc: Add support for AD7091R5 ADC")
Suggested-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Marcelo Schmitt <marcelo.schmitt@analog.com>
Link: https://lore.kernel.org/r/59552d3548dabd56adc3107b7b4869afee2b0c3c.1703013352.git.marcelo.schmitt1@gmail.com
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/iio/adc/ad7091r-base.h b/drivers/iio/adc/ad7091r-base.h
index 509748aef9b1..7a78976a2f80 100644
--- a/drivers/iio/adc/ad7091r-base.h
+++ b/drivers/iio/adc/ad7091r-base.h
@@ -8,6 +8,10 @@
 #ifndef __DRIVERS_IIO_ADC_AD7091R_BASE_H__
 #define __DRIVERS_IIO_ADC_AD7091R_BASE_H__
 
+/* AD7091R_REG_CH_LIMIT */
+#define AD7091R_HIGH_LIMIT		0xFFF
+#define AD7091R_LOW_LIMIT		0x0
+
 struct device;
 struct ad7091r_state;
 
@@ -17,6 +21,8 @@ struct ad7091r_chip_info {
 	unsigned int vref_mV;
 };
 
+extern const struct iio_event_spec ad7091r_events[3];
+
 extern const struct regmap_config ad7091r_regmap_config;
 
 int ad7091r_probe(struct device *dev, const char *name,