iio: adc: add ADC12130/ADC12132/ADC12138 ADC driver

This adds Texas Instruments' ADC12130/ADC12132/ADC12138 12-bit plus
sign ADC driver.  I have tested with the ADC12138.  The ADC12130 and
ADC12132 are not tested but these are similar to ADC12138 except that
the mode programming instruction is a bit different.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>
Cc: Jonathan Cameron <jic23@kernel.org>
Cc: Hartmut Knaack <knaack.h@gmx.de>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: Peter Meerwald <pmeerw@pmeerw.net>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

1 files changed, 37 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/iio/adc/ti-adc12138.txt b/Documentation/devicetree/bindings/iio/adc/ti-adc12138.txt
new file mode 100644
index 000000000000..049a1d36f013
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/adc/ti-adc12138.txt
@@ -0,0 +1,37 @@
+* Texas Instruments' ADC12130/ADC12132/ADC12138
+
+Required properties:
+ - compatible: Should be one of
+	* "ti,adc12130"
+	* "ti,adc12132"
+	* "ti,adc12138"
+ - reg: SPI chip select number for the device
+ - interrupts: Should contain interrupt for EOC (end of conversion)
+ - clocks: phandle to conversion clock input
+ - spi-max-frequency: Definision as per
+	Documentation/devicetree/bindings/spi/spi-bus.txt
+ - vref-p-supply: The regulator supply for positive analog voltage reference
+
+Optional properties:
+ - vref-n-supply: The regulator supply for negative analog voltage reference
+	(Note that this must not go below GND or exceed vref-p)
+	If not specified, this is assumed to be analog ground.
+ - ti,acquisition-time: The number of conversion clock periods for the S/H's
+	acquisition time.  Should be one of 6, 10, 18, 34.  If not specified,
+	default value of 10 is used.
+	For high source impedances, this value can be increased to 18 or 34.
+	For less ADC accuracy and/or slower CCLK frequencies this value may be
+	decreased to 6.  See section 6.0 INPUT SOURCE RESISTANCE in the
+	datasheet for details.
+
+Example:
+adc@0 {
+	compatible = "ti,adc12138";
+	reg = <0>;
+	interrupts = <28 IRQ_TYPE_EDGE_RISING>;
+	interrupt-parent = <&gpio1>;
+	clocks = <&cclk>;
+	vref-p-supply = <&ldo4_reg>;
+	spi-max-frequency = <5000000>;
+	ti,acquisition-time = <6>;
+};