[PATCH] Documentation: acpi: Add an example for PRP0001

Thomas Preston
2019-03-22T13:47:10Z

Add an example for the magic PRP0001 device ID which allows matching
ACPI devices against drivers using OF Device Tree compatible property.
It wasn't clear to me that PRP0001 could be used in _CID.

Signed-off-by: Thomas Preston <thomas.preston@codethink.co.uk>
---
Documentation/acpi/enumeration.txt | 27 +++++++++++++++++++++++++++
1 file changed, 27 insertions(+)

diff --git a/Documentation/acpi/enumeration.txt b/Documentation/acpi/enumeration.txt
index 7bcf9c3d9fbe..391db643065a 100644
--- a/Documentation/acpi/enumeration.txt
+++ b/Documentation/acpi/enumeration.txt
@@ -410,6 +410,33 @@ Specifically, the device IDs returned by _HID and preceding PRP0001 in the _CID
return package will be checked first. Also in that case the bus type the device
will be enumerated to depends on the device ID returned by _HID.

+For example, the following ACPI sample might be used to enumerate an lm75-type
+I2C temperature sensor and match it to the driver using the Device Tree
+namespace link:
+
+ Device (TMP0)
+ {
+ Name (_HID, "TITMP75") /* _HID will appear in sysfs */
+ Name (_CID, "PRP0001")
+ Name (_DSD, Package() {
+ ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
+ Package () {
+ Package (2) { "compatible", "ti,tmp75" },
+ }
+ })
+ Method (_CRS, 0, Serialized)
+ {
+ Name (SBUF, ResourceTemplate ()
+ {
+ I2cSerialBusV2 (0x48, ControllerInitiated,
+ 400000, AddressingMode7Bit,
+ "\\_SB.PCI0.I2C1", 0x00,
+ ResourceConsumer, , Exclusive,)
+ })
+ Return (SBUF)
+ }
+ }
+
It is valid to define device objects with a _HID returning PRP0001 and without
the "compatible" property in the _DSD or a _CID as long as one of their
ancestors provides a _DSD with a valid "compatible" property. Such device
--
2.11.0