iio: adc: Add support for TI ADC108S102 and ADC128S102

This is an upstream port of an IIO driver for the TI ADC108S102 and
ADC128S102. The former can be found on the Intel Galileo Gen2 and the
Siemens SIMATIC IOT2000. For those boards, ACPI-based enumeration is
included.

Due to the lack of regulators under ACPI, we hard-code the voltage
provided to the VA pin of the ADC to 5 V, the value used on Galileo and
IOT2000. For DT usage, the regulator "vref-supply" provides this
information. Note that DT usage has not been tested.

Original author: Bogdan Pricop <bogdan.pricop@emutex.com>
Ported from Intel Galileo Gen2 BSP to Intel Yocto kernel:
Todor Minchev <todor@minchev.co.uk>.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

1 files changed, 18 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/iio/adc/ti-adc108s102.txt b/Documentation/devicetree/bindings/iio/adc/ti-adc108s102.txt
new file mode 100644
index 000000000000..bbbbb4a9f58f
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/adc/ti-adc108s102.txt
@@ -0,0 +1,18 @@
+* Texas Instruments' ADC108S102 and ADC128S102 ADC chip
+
+Required properties:
+ - compatible: Should be "ti,adc108s102"
+ - reg: spi chip select number for the device
+ - vref-supply: The regulator supply for ADC reference voltage
+
+Recommended properties:
+ - spi-max-frequency: Definition as per
+		Documentation/devicetree/bindings/spi/spi-bus.txt
+
+Example:
+adc@0 {
+	compatible = "ti,adc108s102";
+	reg = <0>;
+	vref-supply = <&vdd_supply>;
+	spi-max-frequency = <1000000>;
+};