[PATCH v7 1/9] acpi: Add a binding for ACPI settings in the device tree

Simon Glass sjg at chromium.org
Sun Apr 19 22:36:49 CEST 2020

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 at chromium.org>

Changes in v7: None
Changes in v5: None
Changes in v4:
- Put 'interrupts-extended' property on one line
- Rename acpi-probed to linux,probed
- Note that linux,probed is an out-of-tree feature

Changes in v3:
- Drop mention of PRIC
- Rename acpi,desc to acpi,ddn
- Correct description of acpi,probed
- Drop hid-descr-addr
- Just add the device.txt binding file in this patch
- Change the example to ELAN
- Add a pointer to information about acpi,compatible

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 +++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)
 create mode 100644 doc/device-tree-bindings/device.txt

diff --git a/doc/device-tree-bindings/device.txt b/doc/device-tree-bindings/device.txt
new file mode 100644
index 0000000000..27bd3978d9
--- /dev/null
+++ b/doc/device-tree-bindings/device.txt
@@ -0,0 +1,36 @@
+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. See also
+Documentation/firmware-guide/acpi/enumeration.rst in the Linux kernel for
+the acpi,compatible property.
+ - acpi,has-power-resource : (boolean) true if this device has a power resource.
+    This causes an 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,ddn : 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
+ - acpi,uid : _UID value for device
+ - linux,probed : Tells U-Boot to add 'linux,probed' to the ACPI tables so that
+    Linux will only load the driver if the device can be detected (e.g. on I2C
+    bus). Note that this is an out-of-tree Linux feature.
+elan_touchscreen: elan-touchscreen at 10 {
+	compatible = "i2c-chip";
+	reg = <0x10>;
+	acpi,hid = "ELAN0001";
+	acpi,ddn = "ELAN Touchscreen";
+	interrupts-extended = <&acpi_gpe GPIO_21_IRQ IRQ_TYPE_EDGE_FALLING>;
+	linux,probed;

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