Lines Matching refs:the
10 device tree under the /sys/devices/LNXSYSTEM:00 and updates it upon
12 hierarchy there is a corresponding symbolic link in the
14 This document illustrates the structure of the ACPI device tree.
19 Thanks for the help from Zhang Rui <rui.zhang@intel.com> and Rafael J.
25 The ACPI firmware sets up RSDP (Root System Description Pointer) in the
26 system memory address space pointing to the XSDT (Extended System
27 Description Table). The XSDT always points to the FADT (Fixed ACPI
28 Description Table) using its first entry, the data within the FADT
30 of the hardware. The FADT contains a pointer to the DSDT
38 of the DSDT along with the contents of SSDTs represents a hierarchical
39 data structure called the ACPI namespace whose topology reflects the
40 structure of the underlying hardware platform.
43 are illustrated in the following diagram.
71 NOTE: RSDP can also contain a pointer to the RSDT (Root System
81 The following naming conventions apply to object names in the ACPI
85 3. Each of the remaining bytes of a name must be one of 'A' - 'Z', '0'
87 4. Names starting with '_' are reserved by the ACPI specification.
88 5. The '\' symbol represents the root of the namespace (i.e. names
89 prepended with '\' are relative to the namespace root).
90 6. The '^' symbol represents the parent of the current namespace node
91 (i.e. names prepended with '^' are relative to the parent of the
101 +-| _PR | Scope(_PR): the processor namespace
105 | +-| CPU0 | Processor(CPU0): the first processor
109 +-| _SB | Scope(_SB): the system bus namespace
113 | +-| LID0 | Device(LID0); the lid device
117 | | +-| _HID | Name(_HID, "PNP0C0D"): the hardware ID
121 | | +-| _STA | Method(_STA): the status control method
125 | +-| PCI0 | Device(PCI0); the PCI root bridge
129 | +-| _HID | Name(_HID, "PNP0A08"): the hardware ID
133 | +-| _CID | Name(_CID, "PNP0A03"): the compatible ID
137 | +-| RP03 | Scope(RP03): the PCI0 power scope
141 | | +-| PXP3 | PowerResource(PXP3): the PCI0 power resource
145 | +-| GFX0 | Device(GFX0): the graphics adapter
149 | +-| _ADR | Name(_ADR, 0x00020000): the PCI bus address
153 | +-| DD01 | Device(DD01): the LCD output device
157 | +-| _BCL | Method(_BCL): the backlight control method
161 +-| _TZ | Scope(_TZ): the thermal zone namespace
165 | +-| FN00 | PowerResource(FN00): the FAN0 power resource
169 | +-| FAN0 | Device(FAN0): the FAN0 cooling device
173 | | +-| _HID | Name(_HID, "PNP0A0B"): the hardware ID
177 | +-| TZ00 | ThermalZone(TZ00); the FAN thermal zone
181 +-| _GPE | Scope(_GPE): the GPE namespace
192 sysfs as directories in the subtree under /sys/devices/LNXSYSTM:00. The
193 format of their names is <bus_id:instance>, where 'bus_id' refers to the
194 ACPI namespace representation of the given object and 'instance' is used
195 for distinguishing different object of the same 'bus_id' (it is
198 The value of 'bus_id' depends on the type of the object whose name it is
199 part of as listed in the table below.
230 the basis of the contents of ACPI System Description Tables (as
231 indicated by the letter in the first column and the notation in the
232 second column of the table above):
234 The object's source is an ACPI namespace node (as indicated by the
235 named object's type in the second column). In that case the object's
236 directory in sysfs will contain the 'path' attribute whose value is
237 the full path to the node from the namespace root.
240 feature (as indicated by the fixed feature flag's name in the second
241 column), so its sysfs directory will not contain the 'path'
245 with specific control methods (as indicated by the ACPI defined
246 device's type in the second column). The 'path' attribute containing
248 example, if the _BCL method is present for an ACPI namespace node, a
252 The third column of the above table indicates which ACPI System
253 Description Tables contain information used for the creation of the
254 struct acpi_device objects represented by the given row (xSDT means DSDT
257 The forth column of the above table indicates the 'bus_id' generation
258 rule of the struct acpi_device object:
260 _HID in the last column of the table means that the object's bus_id
261 is derived from the _HID/_CID identification objects present under
262 the corresponding ACPI namespace node. The object's sysfs directory
263 will then contain the 'hid' and 'modalias' attributes that can be
264 used to retrieve the _HID and _CIDs of that object.
267 objects having bus_id of the "LNXxxxxx" form (pseudo devices), in
268 which cases it contains the bus_id string itself.
270 'device' in the last column of the table indicates that the object's
271 bus_id cannot be determined from _HID/_CID of the corresponding
274 or _CID). In that case the string 'device' will be used as the
281 objects in the Linux' device hierarchy that represent "physical" devices
282 (for example, devices on the PCI bus). If that happens, it means that
283 the ACPI device object is a "companion" of a device otherwise
286 (2) to do specific things to the device with the help of its ACPI
291 directory contains the "physical_node" symbolic link to the sysfs
292 directory of the target device object. In turn, the target device's
293 sysfs directory will then contain the "firmware_node" symbolic link to
294 the sysfs directory of the companion ACPI device object.
295 The linking mechanism relies on device identification provided by the
298 object representing a PCI bridge) whose _ADR returns 0x00020000 and the
299 bus number of the parent PCI bridge is 0, the sysfs directory
300 representing the struct acpi_device object created for that ACPI
301 namespace object will contain the 'physical_node' symbolic link to the
302 /sys/devices/pci0000:00/0000:00:02:0/ sysfs directory of the
306 implementation is located in the drivers/acpi/glue.c file, but there are
307 complementary parts depending on the bus types in question located
308 elsewhere. For example, the PCI-specific part of it is located in
314 The sysfs hierarchy of struct acpi_device objects corresponding to the
315 example ACPI namespace illustrated in Figure 2 with the addition of
381 1. 'object' is the name of the object's directory in sysfs.
382 2. 'path' is the ACPI namespace path of the corresponding
383 ACPI namespace object, as returned by the object's 'path'
385 3. 'modalias' is the value of the object's 'modalias' sysfs
387 NOTE: N/A indicates the device object does not have the 'path' or the