[PATCH v2 13/39] acpi: Add a binding for ACPI settings in the device tree

[Simon Glass <sjg@chromium.org>]

Devices need to report various identifiers in the ACPI tables. Rather than
hard-coding these in drivers it is typically better to put them in the
device tree.

Add a binding file to describe this.

Signed-off-by: Simon Glass <sjg@chromium.org>
---

Changes in v2:
- Fix definition of HID
- Infer hid-over-i2c CID value
- Add the hid-over-i2c binding document

 doc/device-tree-bindings/device.txt           | 36 +++++++++++++++
 .../input/hid-over-i2c.txt                    | 44 +++++++++++++++++++
 2 files changed, 80 insertions(+)
 create mode 100644 doc/device-tree-bindings/device.txt
 create mode 100644 doc/device-tree-bindings/input/hid-over-i2c.txt

diff --git a/doc/device-tree-bindings/device.txt b/doc/device-tree-bindings/device.txt
new file mode 100644
index 0000000000..31ec2fa31b
--- /dev/null
+++ b/doc/device-tree-bindings/device.txt
@@ -0,0 +1,36 @@
+Devices
+=======
+
+Device bindings are described by their own individual binding files.
+
+U-Boot provides for some optional properties which are documented here. See
+also hid-over-i2c.txt which describes HID devices.
+
+ - acpi,has-power-resource : (boolean) true if this device has a power resource.
+    This causes a PRIC (ACPI PowerResource) to be written containing the
+    properties provided by this binding, to describe how to handle powering the
+    device up and down using GPIOs
+ - acpi,compatible : compatible string to report
+ - acpi,desc : Contains the string to use as the _DDN (DOS (Disk Operating
+    System) Device Name)
+ - acpi,hid : Contains the string to use as the HID (Hardware ID)
+    identifier _HID
+ - hid-descr-addr : HID register offset (for Human Interface Devices)
+ - acpi,probed : Tells U-Boot to add 'linux,probed' to the ACPI tables so that
+    Linux will not re-init the device
+ - acpi,uid : _UID value for device
+
+
+Example
+-------
+
+synaptics_touchpad: synaptics-touchpad at 2c {
+	compatible = "hid-over-i2c";
+	reg = <0x2c>;
+	acpi,hid = "PNP0C50";
+	acpi,desc = "Synaptics Touchpad";
+	interrupts-extended = <&acpi_gpe GPIO_18_IRQ
+			IRQ_TYPE_EDGE_FALLING>;
+	acpi,probed;
+	hid-descr-addr = <0x20>;
+};
diff --git a/doc/device-tree-bindings/input/hid-over-i2c.txt b/doc/device-tree-bindings/input/hid-over-i2c.txt
new file mode 100644
index 0000000000..c76bafaf98
--- /dev/null
+++ b/doc/device-tree-bindings/input/hid-over-i2c.txt
@@ -0,0 +1,44 @@
+* HID over I2C Device-Tree bindings
+
+HID over I2C provides support for various Human Interface Devices over the
+I2C bus. These devices can be for example touchpads, keyboards, touch screens
+or sensors.
+
+The specification has been written by Microsoft and is currently available here:
+http://msdn.microsoft.com/en-us/library/windows/hardware/hh852380.aspx
+
+If this binding is used, the kernel module i2c-hid will handle the communication
+with the device and the generic hid core layer will handle the protocol.
+
+Required properties:
+- compatible: must be "hid-over-i2c"
+- reg: i2c slave address
+- hid-descr-addr: HID descriptor address
+- interrupts: interrupt line
+
+Additional optional properties:
+
+Some devices may support additional optional properties to help with, e.g.,
+power sequencing. The following properties can be supported by one or more
+device-specific compatible properties, which should be used in addition to the
+"hid-over-i2c" string.
+
+- compatible:
+  * "wacom,w9013" (Wacom W9013 digitizer). Supports:
+    - vdd-supply (3.3V)
+    - vddl-supply (1.8V)
+    - post-power-on-delay-ms
+
+- vdd-supply: phandle of the regulator that provides the supply voltage.
+- post-power-on-delay-ms: time required by the device after enabling its regulators
+  or powering it on, before it is ready for communication.
+
+Example:
+
+	i2c-hid-dev at 2c {
+		compatible = "hid-over-i2c";
+		reg = <0x2c>;
+		hid-descr-addr = <0x0020>;
+		interrupt-parent = <&gpx3>;
+		interrupts = <3 2>;
+	};
-- 
2.25.1.481.gfbce0eb801-goog