diff options
Diffstat (limited to 'Documentation/firmware-guide')
| -rw-r--r-- | Documentation/firmware-guide/acpi/dsd/leds.rst | 111 | ||||
| -rw-r--r-- | Documentation/firmware-guide/acpi/enumeration.rst | 16 | ||||
| -rw-r--r-- | Documentation/firmware-guide/acpi/index.rst | 1 | ||||
| -rw-r--r-- | Documentation/firmware-guide/acpi/namespace.rst | 2 |
4 files changed, 121 insertions, 9 deletions
diff --git a/Documentation/firmware-guide/acpi/dsd/leds.rst b/Documentation/firmware-guide/acpi/dsd/leds.rst new file mode 100644 index 000000000000..946efe2b2936 --- /dev/null +++ b/Documentation/firmware-guide/acpi/dsd/leds.rst @@ -0,0 +1,111 @@ +.. SPDX-License-Identifier: GPL-2.0 +.. include:: <isonum.txt> + +======================================== +Describing and referring to LEDs in ACPI +======================================== + +Individual LEDs are described by hierarchical data extension [6] nodes under the +device node, the LED driver chip. The "reg" property in the LED specific nodes +tells the numerical ID of each individual LED output to which the LEDs are +connected. [3] The hierarchical data nodes are named "led@X", where X is the +number of the LED output. + +Referring to LEDs in Device tree is documented in [4], in "flash-leds" property +documentation. In short, LEDs are directly referred to by using phandles. + +While Device tree allows referring to any node in the tree[1], in ACPI +references are limited to device nodes only [2]. For this reason using the same +mechanism on ACPI is not possible. A mechanism to refer to non-device ACPI nodes +is documented in [7]. + +ACPI allows (as does DT) using integer arguments after the reference. A +combination of the LED driver device reference and an integer argument, +referring to the "reg" property of the relevant LED, is used to identify +individual LEDs. The value of the "reg" property is a contract between the +firmware and software, it uniquely identifies the LED driver outputs. + +Under the LED driver device, The first hierarchical data extension package list +entry shall contain the string "led@" followed by the number of the LED, +followed by the referred object name. That object shall be named "LED" followed +by the number of the LED. + +Example +======= + +An ASL example of a camera sensor device and a LED driver device for two LEDs is +show below. Objects not relevant for LEDs or the references to them have been +omitted. :: + + Device (LED) + { + Name (_DSD, Package () { + ToUUID("dbb8e3e6-5886-4ba6-8795-1319f52a966b"), + Package () { + Package () { "led@0", LED0 }, + Package () { "led@1", LED1 }, + } + }) + Name (LED0, Package () { + ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"), + Package () { + Package () { "reg", 0 }, + Package () { "flash-max-microamp", 1000000 }, + Package () { "flash-timeout-us", 200000 }, + Package () { "led-max-microamp", 100000 }, + Package () { "label", "white:flash" }, + } + }) + Name (LED1, Package () { + ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"), + Package () { + Package () { "reg", 1 }, + Package () { "led-max-microamp", 10000 }, + Package () { "label", "red:indicator" }, + } + }) + } + + Device (SEN) + { + Name (_DSD, Package () { + ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"), + Package () { + Package () { + "flash-leds", + Package () { ^LED, "led@0", ^LED, "led@1" }, + } + } + }) + } + +where +:: + + LED LED driver device + LED0 First LED + LED1 Second LED + SEN Camera sensor device (or another device the LED is related to) + +References +========== + +[1] Device tree. <URL:http://www.devicetree.org>, referenced 2019-02-21. + +[2] Advanced Configuration and Power Interface Specification. + <URL:https://uefi.org/sites/default/files/resources/ACPI_6_3_final_Jan30.pdf>, + referenced 2019-02-21. + +[3] Documentation/devicetree/bindings/leds/common.txt + +[4] Documentation/devicetree/bindings/media/video-interfaces.txt + +[5] Device Properties UUID For _DSD. + <URL:http://www.uefi.org/sites/default/files/resources/_DSD-device-properties-UUID.pdf>, + referenced 2019-02-21. + +[6] Hierarchical Data Extension UUID For _DSD. + <URL:http://www.uefi.org/sites/default/files/resources/_DSD-hierarchical-data-extension-UUID-v1.1.pdf>, + referenced 2019-02-21. + +[7] Documentation/firmware-guide/acpi/dsd/data-node-references.rst diff --git a/Documentation/firmware-guide/acpi/enumeration.rst b/Documentation/firmware-guide/acpi/enumeration.rst index 0a72b6321f5f..c13fee8b02ba 100644 --- a/Documentation/firmware-guide/acpi/enumeration.rst +++ b/Documentation/firmware-guide/acpi/enumeration.rst @@ -71,8 +71,8 @@ DMA support DMA controllers enumerated via ACPI should be registered in the system to provide generic access to their resources. For example, a driver that would like to be accessible to slave devices via generic API call -dma_request_slave_channel() must register itself at the end of the probe -function like this:: +dma_request_chan() must register itself at the end of the probe function like +this:: err = devm_acpi_dma_controller_register(dev, xlate_func, dw); /* Handle the error if it's not a case of !CONFIG_ACPI */ @@ -112,15 +112,15 @@ could look like:: } #endif -dma_request_slave_channel() will call xlate_func() for each registered DMA -controller. In the xlate function the proper channel must be chosen based on +dma_request_chan() will call xlate_func() for each registered DMA controller. +In the xlate function the proper channel must be chosen based on information in struct acpi_dma_spec and the properties of the controller provided by struct acpi_dma. -Clients must call dma_request_slave_channel() with the string parameter that -corresponds to a specific FixedDMA resource. By default "tx" means the first -entry of the FixedDMA resource array, "rx" means the second entry. The table -below shows a layout:: +Clients must call dma_request_chan() with the string parameter that corresponds +to a specific FixedDMA resource. By default "tx" means the first entry of the +FixedDMA resource array, "rx" means the second entry. The table below shows a +layout:: Device (I2C0) { diff --git a/Documentation/firmware-guide/acpi/index.rst b/Documentation/firmware-guide/acpi/index.rst index 90c90d42d9ad..ad3b5afdae77 100644 --- a/Documentation/firmware-guide/acpi/index.rst +++ b/Documentation/firmware-guide/acpi/index.rst @@ -10,6 +10,7 @@ ACPI Support namespace dsd/graph dsd/data-node-references + dsd/leds enumeration osi method-customizing diff --git a/Documentation/firmware-guide/acpi/namespace.rst b/Documentation/firmware-guide/acpi/namespace.rst index 835521baeb89..3eb763d6656d 100644 --- a/Documentation/firmware-guide/acpi/namespace.rst +++ b/Documentation/firmware-guide/acpi/namespace.rst @@ -261,7 +261,7 @@ Description Tables contain information used for the creation of the struct acpi_device objects represented by the given row (xSDT means DSDT or SSDT). -The forth column of the above table indicates the 'bus_id' generation +The fourth column of the above table indicates the 'bus_id' generation rule of the struct acpi_device object: _HID: |
