extcon: Add support for qcom SPMI PMIC USB id detection hardware

Some Qualcomm PMICs have a misc device that performs USB id pin
detection via an interrupt. When the interrupt triggers, we
should read the interrupt line to see if it has gone high or low.
If the interrupt is low then the ID pin is grounded, and if the
interrupt is high then the ID pin is being held high.

Cc: Roger Quadros <rogerq@ti.com>
Signed-off-by: Stephen Boyd <stephen.boyd@linaro.org>
[cw00.choi: Edited the driver description and added the author information]
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>

1 files changed, 41 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/extcon/qcom,pm8941-misc.txt b/Documentation/devicetree/bindings/extcon/qcom,pm8941-misc.txt
new file mode 100644
index 0000000..35383adb
--- /dev/null
+++ b/Documentation/devicetree/bindings/extcon/qcom,pm8941-misc.txt
@@ -0,0 +1,41 @@
+Qualcomm's PM8941 USB ID Extcon device
+
+Some Qualcomm PMICs have a "misc" module that can be used to detect when
+the USB ID pin has been pulled low or high.
+
+PROPERTIES
+
+- compatible:
+    Usage: required
+    Value type: <string>
+    Definition: Should contain "qcom,pm8941-misc";
+
+- reg:
+    Usage: required
+    Value type: <u32>
+    Definition: Should contain the offset to the misc address space
+
+- interrupts:
+    Usage: required
+    Value type: <prop-encoded-array>
+    Definition: Should contain the usb id interrupt
+
+- interrupt-names:
+    Usage: required
+    Value type: <stringlist>
+    Definition: Should contain the string "usb_id" for the usb id interrupt
+
+Example:
+
+	pmic {
+		usb_id: misc@900 {
+			compatible = "qcom,pm8941-misc";
+			reg = <0x900>;
+			interrupts = <0x0 0x9 0 IRQ_TYPE_EDGE_BOTH>;
+			interrupt-names = "usb_id";
+		};
+	}
+
+	usb-controller {
+		extcon = <&usb_id>;
+	};