iio: adc: add STMPE ADC devicetree bindings

This adds the devicetree bindings for the STMPE ADC. This also corrects
a typo in st,sample-time it is rather "6 -> 124 clocks" according
to the datasheet and not 144.
We need to use the naming stmpe_adc in devicetree because this is given
by the mfd device.
Signed-off-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Max Krummenacher <max.krummenacher@toradex.com>
Signed-off-by: Philippe Schenker <philippe.schenker@toradex.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

Documentation/devicetree/bindings/iio/adc/stmpe-adc.txt

+STMPE ADC driver
+----------------
+
+Required properties:
+ - compatible: "st,stmpe-adc"
+
+Optional properties:
+Note that the ADC is shared with the STMPE touchscreen. ADC related settings
+have to be done in the mfd.
+- st,norequest-mask: bitmask specifying which ADC channels should _not_ be
+  requestable due to different usage (e.g. touch)
+
+Node name must be stmpe_adc and should be child node of stmpe node to
+which it belongs.
+
+Example:
+
+	stmpe_adc {
+		compatible = "st,stmpe-adc";
+		st,norequest-mask = <0x0F>; /* dont use ADC CH3-0 */
+	};

Documentation/devicetree/bindings/input/touchscreen/stmpe.txt

@@ -5,24 +5,6 @@ Required properties:
  - compatible: "st,stmpe-ts"
 
 Optional properties:
-- st,sample-time	: ADC conversion time in number of clock.
-				0 -> 36 clocks
-				1 -> 44 clocks
-				2 -> 56 clocks
-				3 -> 64 clocks
-				4 -> 80 clocks (recommended)
-				5 -> 96 clocks
-				6 -> 144 clocks
-- st,mod-12b		: ADC Bit mode
-				0 -> 10bit ADC
-				1 -> 12bit ADC
-- st,ref-sel		: ADC reference source
-				0 -> internal
-				1 -> external
-- st,adc-freq		: ADC Clock speed
-				0 -> 1.625 MHz
-				1 -> 3.25 MHz
-				2 || 3 -> 6.5 MHz
 - st,ave-ctrl		: Sample average control
 				0 -> 1 sample
 				1 -> 2 samples
@@ -52,20 +34,76 @@ Optional properties:
 				0 -> 20 mA (typical 35mA max)
 				1 -> 50 mA (typical 80 mA max)
 
+Optional properties common with MFD (deprecated):
+ - st,sample-time	: ADC conversion time in number of clock.
+				0 -> 36 clocks
+				1 -> 44 clocks
+				2 -> 56 clocks
+				3 -> 64 clocks
+				4 -> 80 clocks (recommended)
+				5 -> 96 clocks
+				6 -> 124 clocks
+ - st,mod-12b		: ADC Bit mode
+				0 -> 10bit ADC
+				1 -> 12bit ADC
+ - st,ref-sel		: ADC reference source
+				0 -> internal
+				1 -> external
+ - st,adc-freq		: ADC Clock speed
+				0 -> 1.625 MHz
+				1 -> 3.25 MHz
+				2 || 3 -> 6.5 MHz
+
 Node name must be stmpe_touchscreen and should be child node of stmpe node to
 which it belongs.
 
+Note that common ADC settings of stmpe_touchscreen (child) will take precedence
+over the settings done in MFD.
+
 Example:
 
+stmpe811@41 {
+	compatible = "st,stmpe811";
+	pinctrl-names = "default";
+	pinctrl-0 = <&pinctrl_touch_int>;
+	#address-cells = <1>;
+	#size-cells = <0>;
+	reg = <0x41>;
+	interrupts = <10 IRQ_TYPE_LEVEL_LOW>;
+	interrupt-parent = <&gpio4>;
+	interrupt-controller;
+	id = <0>;
+	blocks = <0x5>;
+	irq-trigger = <0x1>;
+	/* Common ADC settings */
+	/* 3.25 MHz ADC clock speed */
+	st,adc-freq = <1>;
+	/* 12-bit ADC */
+	st,mod-12b = <1>;
+	/* internal ADC reference */
+	st,ref-sel = <0>;
+	/* ADC converstion time: 80 clocks */
+	st,sample-time = <4>;
+
 	stmpe_touchscreen {
 		compatible = "st,stmpe-ts";
-		st,sample-time = <4>;
-		st,mod-12b = <1>;
-		st,ref-sel = <0>;
-		st,adc-freq = <1>;
-		st,ave-ctrl = <1>;
-		st,touch-det-delay = <2>;
-		st,settling = <2>;
+		reg = <0>;
+		/* 8 sample average control */
+		st,ave-ctrl = <3>;
+		/* 5 ms touch detect interrupt delay */
+		st,touch-det-delay = <5>;
+		/* 1 ms panel driver settling time */
+		st,settling = <3>;
+		/* 7 length fractional part in z */
 		st,fraction-z = <7>;
+		/*
+		 * 50 mA typical 80 mA max touchscreen drivers
+		 * current limit value
+		 */
 		st,i-drive = <1>;
 	};
+	stmpe_adc {
+		compatible = "st,stmpe-adc";
+		st,norequest-mask = <0x0F>;
+	};
+};

Documentation/devicetree/bindings/mfd/stmpe.txt

@@ -14,6 +14,20 @@ Optional properties:
  - st,autosleep-timeout		: Valid entries (ms); 4, 16, 32, 64, 128, 256, 512 and 1024
  - irq-gpio			: If present, which GPIO to use for event IRQ
 
+Optional properties for devices with touch and ADC (STMPE811|STMPE610):
+ - st,sample-time		: ADC conversion time in number of clock.
+					0 -> 36 clocks		4 -> 80 clocks (recommended)
+					1 -> 44 clocks		5 -> 96 clocks
+					2 -> 56 clocks		6 -> 124 clocks
+					3 -> 64 clocks
+ - st,mod-12b			: ADC Bit mode
+					0 -> 10bit ADC		1 -> 12bit ADC
+ - st,ref-sel			: ADC reference source
+					0 -> internal		1 -> external
+ - st,adc-freq			: ADC Clock speed
+					0 -> 1.625 MHz		2 || 3 -> 6.5 MHz
+					1 -> 3.25 MHz
+
 Example:
 
 	stmpe1601: stmpe1601@40 {