iio: at91_adc: add low and high res support

at91 adc offers the choice between two resolutions: low and high.
The low and high resolution values depends on adc IP version, as many IP
properties have been exposed through device tree, these settings have also
been added to the dt bindings.

Signed-off-by: Ludovic Desroches <ludovic.desroches@atmel.com>
Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

1 files changed, 11 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/arm/atmel-adc.txt b/Documentation/devicetree/bindings/arm/atmel-adc.txt
index c63097d..fd2d69e 100644
--- a/Documentation/devicetree/bindings/arm/atmel-adc.txt
+++ b/Documentation/devicetree/bindings/arm/atmel-adc.txt
@@ -14,9 +14,17 @@ Required properties:
   - atmel,adc-status-register: Offset of the Interrupt Status Register
   - atmel,adc-trigger-register: Offset of the Trigger Register
   - atmel,adc-vref: Reference voltage in millivolts for the conversions
+  - atmel,adc-res: List of resolution in bits supported by the ADC. List size
+		   must be two at least.
+  - atmel,adc-res-names: Contains one identifier string for each resolution
+			 in atmel,adc-res property. "lowres" and "highres"
+			 identifiers are required.
 
 Optional properties:
   - atmel,adc-use-external: Boolean to enable of external triggers
+  - atmel,adc-use-res: String corresponding to an identifier from
+		       atmel,adc-res-names property. If not specified, the highest
+		       resolution will be used.
  
 Optional trigger Nodes:
   - Required properties:
@@ -40,6 +48,9 @@ adc0: adc@fffb0000 {
 	atmel,adc-trigger-register = <0x08>;
 	atmel,adc-use-external;
 	atmel,adc-vref = <3300>;
+	atmel,adc-res = <8 10>;
+	atmel,adc-res-names = "lowres", "highres";
+	atmel,adc-use-res = "lowres";
 
 	trigger@0 {
 		trigger-name = "external-rising";