[PATCH v4 16/31] acpi: Add a binding for ACPI settings in the device tree

From: Simon Glass <sjg@chromium.org>
To: u-boot@lists.denx.de
Subject: [PATCH v4 16/31] acpi: Add a binding for ACPI settings in the device tree
Date: Tue,  7 Apr 2020 21:00:52 -0600	[thread overview]
Message-ID: <20200407210023.v4.16.I7842b2dd0d6b475301fc044c6640d8089873053f@changeid> (raw)
In-Reply-To: <20200408030107.168474-1-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 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 00000000000..27bd3978d98
--- /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. 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.
+
+
+Example
+-------
+
+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;
+};
-- 
2.26.0.292.g33ef6b2f38-goog
