Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

3 files changed, 120 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/iio/afe/current-sense-amplifier.txt b/Documentation/devicetree/bindings/iio/afe/current-sense-amplifier.txt
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+++ b/Documentation/devicetree/bindings/iio/afe/current-sense-amplifier.txt
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+Current Sense Amplifier
+=======================
+
+When an io-channel measures the output voltage from a current sense
+amplifier, the interesting measurement is almost always the current
+through the sense resistor, not the voltage output. This binding
+describes such a current sense circuit.
+
+Required properties:
+- compatible : "current-sense-amplifier"
+- io-channels : Channel node of a voltage io-channel.
+- sense-resistor-micro-ohms : The sense resistance in microohms.
+
+Optional properties:
+- sense-gain-mult: Amplifier gain multiplier. The default is <1>.
+- sense-gain-div: Amplifier gain divider. The default is <1>.
+
+Example:
+
+sysi {
+	compatible = "current-sense-amplifier";
+	io-channels = <&tiadc 0>;
+
+	sense-resistor-micro-ohms = <20000>;
+	sense-gain-mul = <50>;
+};
diff --git a/Documentation/devicetree/bindings/iio/afe/current-sense-shunt.txt b/Documentation/devicetree/bindings/iio/afe/current-sense-shunt.txt
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+Current Sense Shunt
+===================
+
+When an io-channel measures the voltage over a current sense shunt,
+the interesting measurement is almost always the current through the
+shunt, not the voltage over it. This binding describes such a current
+sense circuit.
+
+Required properties:
+- compatible : "current-sense-shunt"
+- io-channels : Channel node of a voltage io-channel.
+- shunt-resistor-micro-ohms : The shunt resistance in microohms.
+
+Example:
+The system current is measured by measuring the voltage over a
+3.3 ohms shunt resistor.
+
+sysi {
+	compatible = "current-sense-shunt";
+	io-channels = <&tiadc 0>;
+
+	/* Divide the voltage by 3300000/1000000 (or 3.3) for the current. */
+	shunt-resistor-micro-ohms = <3300000>;
+};
+
+&i2c {
+	tiadc: adc@48 {
+		compatible = "ti,ads1015";
+		reg = <0x48>;
+		#io-channel-cells = <1>;
+
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		channel@0 { /* IN0,IN1 differential */
+			reg = <0>;
+			ti,gain = <1>;
+			ti,datarate = <4>;
+		};
+	};
+};
diff --git a/Documentation/devicetree/bindings/iio/afe/voltage-divider.txt b/Documentation/devicetree/bindings/iio/afe/voltage-divider.txt
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+Voltage divider
+===============
+
+When an io-channel measures the midpoint of a voltage divider, the
+interesting voltage is often the voltage over the full resistance
+of the divider. This binding describes the voltage divider in such
+a curcuit.
+
+    Vin ----.
+            |
+         .-----.
+         |  R  |
+         '-----'
+            |
+            +---- Vout
+            |
+         .-----.
+         | Rout|
+         '-----'
+            |
+           GND
+
+Required properties:
+- compatible : "voltage-divider"
+- io-channels : Channel node of a voltage io-channel measuring Vout.
+- output-ohms : Resistance Rout over which the output voltage is measured.
+	        See full-ohms.
+- full-ohms : Resistance R + Rout for the full divider. The io-channel
+	      is scaled by the Rout / (R + Rout) quotient.
+
+Example:
+The system voltage is circa 12V, but divided down with a 22/222
+voltage divider (R = 200 Ohms, Rout = 22 Ohms) and fed to an ADC.
+
+sysv {
+	compatible = "voltage-divider";
+	io-channels = <&maxadc 1>;
+
+	/* Scale the system voltage by 22/222 to fit the ADC range. */
+	output-ohms = <22>;
+	full-ohms = <222>; /* 200 + 22 */
+};
+
+&spi {
+	maxadc: adc@0 {
+		compatible = "maxim,max1027";
+		reg = <0>;
+		#io-channel-cells = <1>;
+		interrupt-parent = <&gpio5>;
+		interrupts = <15 IRQ_TYPE_EDGE_RISING>;
+		spi-max-frequency = <1000000>;
+	};
+};