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YEN SIGN h]h¥}hjLsbah}(h]h ]h"]yenah$]h&]uh1hhhhKRhhhhubhsection)}(hhh](htitle)}(h3ACPI Device Tree - Representation of ACPI Namespaceh]h3ACPI Device Tree - Representation of ACPI Namespace}(hjbhhhNhNubah}(h]h ]h"]h$]h&]uh1j`hj]hhhhhKubh field_list)}(hhh](hfield)}(hhh](h field_name)}(h Copyrighth]h Copyright}(hj|hhhNhNubah}(h]h ]h"]h$]h&]uh1jzhjwhhhKubh field_body)}(h|copy| 2013, Intel Corporation h]h paragraph)}(h|copy| 2013, Intel Corporationh](h©}(hjhhhNhNubh 2013, Intel Corporation}(hjhhhNhNubeh}(h]h ]h"]h$]h&]uh1jhhhKhjubah}(h]h ]h"]h$]h&]uh1jhjwubeh}(h]h ]h"]h$]h&]uh1juhhhKhjrhhubjv)}(hhh](j{)}(hAuthorh]hAuthor}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1jzhjhhhKubj)}(hLv Zheng h]j)}(hLv Zheng h](h Lv Zheng <}(hjhhhNhNubh reference)}(hlv.zheng@intel.comh]hlv.zheng@intel.com}(hjhhhNhNubah}(h]h ]h"]h$]h&]refurimailto:lv.zheng@intel.comuh1jhjubh>}(hjhhhNhNubeh}(h]h ]h"]h$]h&]uh1jhhhK hjubah}(h]h ]h"]h$]h&]uh1jhjubeh}(h]h ]h"]h$]h&]uh1juhhhK hjrhhubjv)}(hhh](j{)}(hCredith]hCredit}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1jzhjhhhKubj)}(hlThanks for the help from Zhang Rui and Rafael J.Wysocki . h]j)}(hkThanks for the help from Zhang Rui and Rafael J.Wysocki .h](h$Thanks for the help from Zhang Rui <}(hj hhhNhNubj)}(hrui.zhang@intel.comh]hrui.zhang@intel.com}(hjhhhNhNubah}(h]h ]h"]h$]h&]refurimailto:rui.zhang@intel.comuh1jhj ubh> and Rafael J.Wysocki <}(hj hhhNhNubj)}(hrafael.j.wysocki@intel.comh]hrafael.j.wysocki@intel.com}(hj&hhhNhNubah}(h]h ]h"]h$]h&]refuri!mailto:rafael.j.wysocki@intel.comuh1jhj ubh>.}(hj hhhNhNubeh}(h]h ]h"]h$]h&]uh1jhhhK hjubah}(h]h ]h"]h$]h&]uh1jhjubeh}(h]h ]h"]h$]h&]uh1juhhhK hjrhhubeh}(h]h ]h"]h$]h&]uh1jphj]hhhhhKubj\)}(hhh](ja)}(hAbstracth]hAbstract}(hjUhhhNhNubah}(h]h ]h"]h$]h&]uh1j`hjRhhhhhKubj)}(hX#The Linux ACPI subsystem converts ACPI namespace objects into a Linux device tree under the /sys/devices/LNXSYSTM:00 and updates it upon receiving ACPI hotplug notification events. For each device object in this hierarchy there is a corresponding symbolic link in the /sys/bus/acpi/devices.h]hX#The Linux ACPI subsystem converts ACPI namespace objects into a Linux device tree under the /sys/devices/LNXSYSTM:00 and updates it upon receiving ACPI hotplug notification events. For each device object in this hierarchy there is a corresponding symbolic link in the /sys/bus/acpi/devices.}(hjchhhNhNubah}(h]h ]h"]h$]h&]uh1jhhhKhjRhhubj)}(h@This document illustrates the structure of the ACPI device tree.h]h@This document illustrates the structure of the ACPI device tree.}(hjqhhhNhNubah}(h]h ]h"]h$]h&]uh1jhhhKhjRhhubeh}(h]abstractah ]h"]abstractah$]h&]uh1j[hj]hhhhhKubj\)}(hhh](ja)}(hACPI Definition Blocksh]hACPI Definition Blocks}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1j`hjhhhhhKubj)}(hX'The ACPI firmware sets up RSDP (Root System Description Pointer) in the system memory address space pointing to the XSDT (Extended System Description Table). The XSDT always points to the FADT (Fixed ACPI Description Table) using its first entry, the data within the FADT includes various fixed-length entries that describe fixed ACPI features of the hardware. The FADT contains a pointer to the DSDT (Differentiated System Description Table). The XSDT also contains entries pointing to possibly multiple SSDTs (Secondary System Description Table).h]hX'The ACPI firmware sets up RSDP (Root System Description Pointer) in the system memory address space pointing to the XSDT (Extended System Description Table). The XSDT always points to the FADT (Fixed ACPI Description Table) using its first entry, the data within the FADT includes various fixed-length entries that describe fixed ACPI features of the hardware. The FADT contains a pointer to the DSDT (Differentiated System Description Table). The XSDT also contains entries pointing to possibly multiple SSDTs (Secondary System Description Table).}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1jhhhKhjhhubj)}(hXThe DSDT and SSDT data is organized in data structures called definition blocks that contain definitions of various objects, including ACPI control methods, encoded in AML (ACPI Machine Language). The data block of the DSDT along with the contents of SSDTs represents a hierarchical data structure called the ACPI namespace whose topology reflects the structure of the underlying hardware platform.h]hXThe DSDT and SSDT data is organized in data structures called definition blocks that contain definitions of various objects, including ACPI control methods, encoded in AML (ACPI Machine Language). The data block of the DSDT along with the contents of SSDTs represents a hierarchical data structure called the ACPI namespace whose topology reflects the structure of the underlying hardware platform.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1jhhhK&hjhhubj)}(hrThe relationships between ACPI System Definition Tables described above are illustrated in the following diagram::h]hqThe relationships between ACPI System Definition Tables described above are illustrated in the following diagram:}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1jhhhK-hjhhubh literal_block)}(hX:+---------+ +-------+ +--------+ +------------------------+ | RSDP | +->| XSDT | +->| FADT | | +-------------------+ | +---------+ | +-------+ | +--------+ +-|->| DSDT | | | Pointer | | | Entry |-+ | ...... | | | +-------------------+ | +---------+ | +-------+ | X_DSDT |--+ | | Definition Blocks | | | Pointer |-+ | ..... | | ...... | | +-------------------+ | +---------+ +-------+ +--------+ | +-------------------+ | | Entry |------------------|->| SSDT | | +- - - -+ | +-------------------| | | Entry | - - - - - - - -+ | | Definition Blocks | | +- - - -+ | | +-------------------+ | | | +- - - - - - - - - -+ | +-|->| SSDT | | | +-------------------+ | | | Definition Blocks | | | +- - - - - - - - - -+ | +------------------------+ | OSPM Loading | \|/ +----------------+ | ACPI Namespace | +----------------+ Figure 1. ACPI Definition Blocksh]hX:+---------+ +-------+ +--------+ +------------------------+ | RSDP | +->| XSDT | +->| FADT | | +-------------------+ | +---------+ | +-------+ | +--------+ +-|->| DSDT | | | Pointer | | | Entry |-+ | ...... | | | +-------------------+ | +---------+ | +-------+ | X_DSDT |--+ | | Definition Blocks | | | Pointer |-+ | ..... | | ...... | | +-------------------+ | +---------+ +-------+ +--------+ | +-------------------+ | | Entry |------------------|->| SSDT | | +- - - -+ | +-------------------| | | Entry | - - - - - - - -+ | | Definition Blocks | | +- - - -+ | | +-------------------+ | | | +- - - - - - - - - -+ | +-|->| SSDT | | | +-------------------+ | | | Definition Blocks | | | +- - - - - - - - - -+ | +------------------------+ | OSPM Loading | \|/ +----------------+ | ACPI Namespace | +----------------+ Figure 1. ACPI Definition Blocks}hjsbah}(h]h ]h"]h$]h&]hhuh1jhhhK0hjhhubhnote)}(hRSDP can also contain a pointer to the RSDT (Root System Description Table). Platforms provide RSDT to enable compatibility with ACPI 1.0 operating systems. The OS is expected to use XSDT, if present.h]j)}(hRSDP can also contain a pointer to the RSDT (Root System Description Table). Platforms provide RSDT to enable compatibility with ACPI 1.0 operating systems. The OS is expected to use XSDT, if present.h]hRSDP can also contain a pointer to the RSDT (Root System Description Table). Platforms provide RSDT to enable compatibility with ACPI 1.0 operating systems. The OS is expected to use XSDT, if present.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1jhhhKJhjubah}(h]h ]h"]h$]h&]uh1jhjhhhhhNubeh}(h]acpi-definition-blocksah ]h"]acpi definition blocksah$]h&]uh1j[hj]hhhhhKubj\)}(hhh](ja)}(hExample ACPI Namespaceh]hExample ACPI Namespace}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1j`hjhhhhhKQubj)}(hAll definition blocks are loaded into a single namespace. The namespace is a hierarchy of objects identified by names and paths. The following naming conventions apply to object names in the ACPI namespace:h]hAll definition blocks are loaded into a single namespace. The namespace is a hierarchy of objects identified by names and paths. The following naming conventions apply to object names in the ACPI namespace:}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1jhhhKShjhhubh block_quote)}(hX1. All names are 32 bits long. 2. The first byte of a name must be one of 'A' - 'Z', '_'. 3. Each of the remaining bytes of a name must be one of 'A' - 'Z', '0' - '9', '_'. 4. Names starting with '_' are reserved by the ACPI specification. 5. The '\' symbol represents the root of the namespace (i.e. names prepended with '\' are relative to the namespace root). 6. The '^' symbol represents the parent of the current namespace node (i.e. names prepended with '^' are relative to the parent of the current namespace node). h]henumerated_list)}(hhh](h list_item)}(hAll names are 32 bits long.h]j)}(hj"h]hAll names are 32 bits long.}(hj$hhhNhNubah}(h]h ]h"]h$]h&]uh1jhhhKXhj ubah}(h]h ]h"]h$]h&]uh1jhjubj)}(h7The first byte of a name must be one of 'A' - 'Z', '_'.h]j)}(hj9h]hCThe first byte of a name must be one of ‘A’ - ‘Z’, ‘_’.}(hj;hhhNhNubah}(h]h ]h"]h$]h&]uh1jhhhKYhj7ubah}(h]h ]h"]h$]h&]uh1jhjubj)}(hOEach of the remaining bytes of a name must be one of 'A' - 'Z', '0' - '9', '_'.h]j)}(hOEach of the remaining bytes of a name must be one of 'A' - 'Z', '0' - '9', '_'.h]hcEach of the remaining bytes of a name must be one of ‘A’ - ‘Z’, ‘0’ - ‘9’, ‘_’.}(hjRhhhNhNubah}(h]h ]h"]h$]h&]uh1jhhhKZhjNubah}(h]h ]h"]h$]h&]uh1jhjubj)}(h?Names starting with '_' are reserved by the ACPI specification.h]j)}(hjhh]hCNames starting with ‘_’ are reserved by the ACPI specification.}(hjjhhhNhNubah}(h]h ]h"]h$]h&]uh1jhhhK\hjfubah}(h]h ]h"]h$]h&]uh1jhjubj)}(hwThe '\' symbol represents the root of the namespace (i.e. names prepended with '\' are relative to the namespace root).h]j)}(hwThe '\' symbol represents the root of the namespace (i.e. names prepended with '\' are relative to the namespace root).h]h{The ‘' symbol represents the root of the namespace (i.e. names prepended with ‘' are relative to the namespace root).}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1jhhhK]hj}ubah}(h]h ]h"]h$]h&]uh1jhjubj)}(hThe '^' symbol represents the parent of the current namespace node (i.e. names prepended with '^' are relative to the parent of the current namespace node). h]j)}(hThe '^' symbol represents the parent of the current namespace node (i.e. names prepended with '^' are relative to the parent of the current namespace node).h]hThe ‘^’ symbol represents the parent of the current namespace node (i.e. names prepended with ‘^’ are relative to the parent of the current namespace node).}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1jhhhK_hjubah}(h]h ]h"]h$]h&]uh1jhjubeh}(h]h ]h"]h$]h&]enumtypearabicprefixhsuffix.uh1jhjubah}(h]h ]h"]h$]h&]uh1jhhhKXhjhhubj)}(h2The figure below shows an example ACPI namespace::h]h1The figure below shows an example ACPI namespace:}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1jhhhKchjhhubj)}(hX +------+ | \ | Root +------+ | | +------+ +-| _PR | Scope(_PR): the processor namespace | +------+ | | | | +------+ | +-| CPU0 | Processor(CPU0): the first processor | +------+ | | +------+ +-| _SB | Scope(_SB): the system bus namespace | +------+ | | | | +------+ | +-| LID0 | Device(LID0); the lid device | | +------+ | | | | | | +------+ | | +-| _HID | Name(_HID, "PNP0C0D"): the hardware ID | | | +------+ | | | | | | +------+ | | +-| _STA | Method(_STA): the status control method | | +------+ | | | | +------+ | +-| PCI0 | Device(PCI0); the PCI root bridge | +------+ | | | | +------+ | +-| _HID | Name(_HID, "PNP0A08"): the hardware ID | | +------+ | | | | +------+ | +-| _CID | Name(_CID, "PNP0A03"): the compatible ID | | +------+ | | | | +------+ | +-| RP03 | Scope(RP03): the PCI0 power scope | | +------+ | | | | | | +------+ | | +-| PXP3 | PowerResource(PXP3): the PCI0 power resource | | +------+ | | | | +------+ | +-| GFX0 | Device(GFX0): the graphics adapter | +------+ | | | | +------+ | +-| _ADR | Name(_ADR, 0x00020000): the PCI bus address | | +------+ | | | | +------+ | +-| DD01 | Device(DD01): the LCD output device | +------+ | | | | +------+ | +-| _BCL | Method(_BCL): the backlight control method | +------+ | | +------+ +-| _TZ | Scope(_TZ): the thermal zone namespace | +------+ | | | | +------+ | +-| FN00 | PowerResource(FN00): the FAN0 power resource | | +------+ | | | | +------+ | +-| FAN0 | Device(FAN0): the FAN0 cooling device | | +------+ | | | | | | +------+ | | +-| _HID | Name(_HID, "PNP0A0B"): the hardware ID | | +------+ | | | | +------+ | +-| TZ00 | ThermalZone(TZ00); the FAN thermal zone | +------+ | | +------+ +-| _GPE | Scope(_GPE): the GPE namespace +------+ Figure 2. Example ACPI Namespaceh]hX +------+ | \ | Root +------+ | | +------+ +-| _PR | Scope(_PR): the processor namespace | +------+ | | | | +------+ | +-| CPU0 | Processor(CPU0): the first processor | +------+ | | +------+ +-| _SB | Scope(_SB): the system bus namespace | +------+ | | | | +------+ | +-| LID0 | Device(LID0); the lid device | | +------+ | | | | | | +------+ | | +-| _HID | Name(_HID, "PNP0C0D"): the hardware ID | | | +------+ | | | | | | +------+ | | +-| _STA | Method(_STA): the status control method | | +------+ | | | | +------+ | +-| PCI0 | Device(PCI0); the PCI root bridge | +------+ | | | | +------+ | +-| _HID | Name(_HID, "PNP0A08"): the hardware ID | | +------+ | | | | +------+ | +-| _CID | Name(_CID, "PNP0A03"): the compatible ID | | +------+ | | | | +------+ | +-| RP03 | Scope(RP03): the PCI0 power scope | | +------+ | | | | | | +------+ | | +-| PXP3 | PowerResource(PXP3): the PCI0 power resource | | +------+ | | | | +------+ | +-| GFX0 | Device(GFX0): the graphics adapter | +------+ | | | | +------+ | +-| _ADR | Name(_ADR, 0x00020000): the PCI bus address | | +------+ | | | | +------+ | +-| DD01 | Device(DD01): the LCD output device | +------+ | | | | +------+ | +-| _BCL | Method(_BCL): the backlight control method | +------+ | | +------+ +-| _TZ | Scope(_TZ): the thermal zone namespace | +------+ | | | | +------+ | +-| FN00 | PowerResource(FN00): the FAN0 power resource | | +------+ | | | | +------+ | +-| FAN0 | Device(FAN0): the FAN0 cooling device | | +------+ | | | | | | +------+ | | +-| _HID | Name(_HID, "PNP0A0B"): the hardware ID | | +------+ | | | | +------+ | +-| TZ00 | ThermalZone(TZ00); the FAN thermal zone | +------+ | | +------+ +-| _GPE | Scope(_GPE): the GPE namespace +------+ Figure 2. Example ACPI Namespace}hjsbah}(h]h ]h"]h$]h&]hhuh1jhhhKehjhhubeh}(h]example-acpi-namespaceah ]h"]example acpi namespaceah$]h&]uh1j[hj]hhhhhKQubj\)}(hhh](ja)}(hLinux ACPI Device Objectsh]hLinux ACPI Device Objects}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1j`hjhhhhhKubj)}(hX(The Linux kernel's core ACPI subsystem creates struct acpi_device objects for ACPI namespace objects representing devices, power resources processors, thermal zones. Those objects are exported to user space via sysfs as directories in the subtree under /sys/devices/LNXSYSTM:00. The format of their names is , where 'bus_id' refers to the ACPI namespace representation of the given object and 'instance' is used for distinguishing different object of the same 'bus_id' (it is two-digit decimal representation of an unsigned integer).h]hX6The Linux kernel’s core ACPI subsystem creates struct acpi_device objects for ACPI namespace objects representing devices, power resources processors, thermal zones. Those objects are exported to user space via sysfs as directories in the subtree under /sys/devices/LNXSYSTM:00. The format of their names is , where ‘bus_id’ refers to the ACPI namespace representation of the given object and ‘instance’ is used for distinguishing different object of the same ‘bus_id’ (it is two-digit decimal representation of an unsigned integer).}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1jhhhKhjhhubj)}(hoThe value of 'bus_id' depends on the type of the object whose name it is part of as listed in the table below::h]hrThe value of ‘bus_id’ depends on the type of the object whose name it is part of as listed in the table below:}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1jhhhKhjhhubj)}(hX\+---+-----------------+-------+----------+ | | Object/Feature | Table | bus_id | +---+-----------------+-------+----------+ | N | Root | xSDT | LNXSYSTM | +---+-----------------+-------+----------+ | N | Device | xSDT | _HID | +---+-----------------+-------+----------+ | N | Processor | xSDT | LNXCPU | +---+-----------------+-------+----------+ | N | ThermalZone | xSDT | LNXTHERM | +---+-----------------+-------+----------+ | N | PowerResource | xSDT | LNXPOWER | +---+-----------------+-------+----------+ | N | Other Devices | xSDT | device | +---+-----------------+-------+----------+ | F | PWR_BUTTON | FADT | LNXPWRBN | +---+-----------------+-------+----------+ | F | SLP_BUTTON | FADT | LNXSLPBN | +---+-----------------+-------+----------+ | M | Video Extension | xSDT | LNXVIDEO | +---+-----------------+-------+----------+ | M | ATA Controller | xSDT | LNXIOBAY | +---+-----------------+-------+----------+ | M | Docking Station | xSDT | LNXDOCK | +---+-----------------+-------+----------+ Table 1. ACPI Namespace Objects Mappingh]hX\+---+-----------------+-------+----------+ | | Object/Feature | Table | bus_id | +---+-----------------+-------+----------+ | N | Root | xSDT | LNXSYSTM | +---+-----------------+-------+----------+ | N | Device | xSDT | _HID | +---+-----------------+-------+----------+ | N | Processor | xSDT | LNXCPU | +---+-----------------+-------+----------+ | N | ThermalZone | xSDT | LNXTHERM | +---+-----------------+-------+----------+ | N | PowerResource | xSDT | LNXPOWER | +---+-----------------+-------+----------+ | N | Other Devices | xSDT | device | +---+-----------------+-------+----------+ | F | PWR_BUTTON | FADT | LNXPWRBN | +---+-----------------+-------+----------+ | F | SLP_BUTTON | FADT | LNXSLPBN | +---+-----------------+-------+----------+ | M | Video Extension | xSDT | LNXVIDEO | +---+-----------------+-------+----------+ | M | ATA Controller | xSDT | LNXIOBAY | +---+-----------------+-------+----------+ | M | Docking Station | xSDT | LNXDOCK | +---+-----------------+-------+----------+ Table 1. ACPI Namespace Objects Mapping}hjsbah}(h]h ]h"]h$]h&]hhuh1jhhhKhjhhubj)}(hThe following rules apply when creating struct acpi_device objects on the basis of the contents of ACPI System Description Tables (as indicated by the letter in the first column and the notation in the second column of the table above):h]hThe following rules apply when creating struct acpi_device objects on the basis of the contents of ACPI System Description Tables (as indicated by the letter in the first column and the notation in the second column of the table above):}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1jhhhKhjhhubj)}(hXN: The object's source is an ACPI namespace node (as indicated by the named object's type in the second column). In that case the object's directory in sysfs will contain the 'path' attribute whose value is the full path to the node from the namespace root. F: The struct acpi_device object is created for a fixed hardware feature (as indicated by the fixed feature flag's name in the second column), so its sysfs directory will not contain the 'path' attribute. M: The struct acpi_device object is created for an ACPI namespace node with specific control methods (as indicated by the ACPI defined device's type in the second column). The 'path' attribute containing its namespace path will be present in its sysfs directory. For example, if the _BCL method is present for an ACPI namespace node, a struct acpi_device object with LNXVIDEO 'bus_id' will be created for it. h]hdefinition_list)}(hhh](hdefinition_list_item)}(hXN: The object's source is an ACPI namespace node (as indicated by the named object's type in the second column). In that case the object's directory in sysfs will contain the 'path' attribute whose value is the full path to the node from the namespace root.h](hterm)}(hN:h]hN:}(hj<hhhNhNubah}(h]h ]h"]h$]h&]uh1j:hhhKhj6ubh definition)}(hhh]j)}(hThe object's source is an ACPI namespace node (as indicated by the named object's type in the second column). In that case the object's directory in sysfs will contain the 'path' attribute whose value is the full path to the node from the namespace root.h]hX The object’s source is an ACPI namespace node (as indicated by the named object’s type in the second column). In that case the object’s directory in sysfs will contain the ‘path’ attribute whose value is the full path to the node from the namespace root.}(hjOhhhNhNubah}(h]h ]h"]h$]h&]uh1jhhhKhjLubah}(h]h ]h"]h$]h&]uh1jJhj6ubeh}(h]h ]h"]h$]h&]uh1j4hhhKhj1ubj5)}(hF: The struct acpi_device object is created for a fixed hardware feature (as indicated by the fixed feature flag's name in the second column), so its sysfs directory will not contain the 'path' attribute.h](j;)}(hF:h]hF:}(hjmhhhNhNubah}(h]h ]h"]h$]h&]uh1j:hhhKhjiubjK)}(hhh]j)}(hThe struct acpi_device object is created for a fixed hardware feature (as indicated by the fixed feature flag's name in the second column), so its sysfs directory will not contain the 'path' attribute.h]hThe struct acpi_device object is created for a fixed hardware feature (as indicated by the fixed feature flag’s name in the second column), so its sysfs directory will not contain the ‘path’ attribute.}(hj~hhhNhNubah}(h]h ]h"]h$]h&]uh1jhhhKhj{ubah}(h]h ]h"]h$]h&]uh1jJhjiubeh}(h]h ]h"]h$]h&]uh1j4hhhKhj1ubj5)}(hXM: The struct acpi_device object is created for an ACPI namespace node with specific control methods (as indicated by the ACPI defined device's type in the second column). The 'path' attribute containing its namespace path will be present in its sysfs directory. For example, if the _BCL method is present for an ACPI namespace node, a struct acpi_device object with LNXVIDEO 'bus_id' will be created for it. h](j;)}(hM:h]hM:}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1j:hhhMhjubjK)}(hhh]j)}(hXThe struct acpi_device object is created for an ACPI namespace node with specific control methods (as indicated by the ACPI defined device's type in the second column). The 'path' attribute containing its namespace path will be present in its sysfs directory. For example, if the _BCL method is present for an ACPI namespace node, a struct acpi_device object with LNXVIDEO 'bus_id' will be created for it.h]hXThe struct acpi_device object is created for an ACPI namespace node with specific control methods (as indicated by the ACPI defined device’s type in the second column). The ‘path’ attribute containing its namespace path will be present in its sysfs directory. For example, if the _BCL method is present for an ACPI namespace node, a struct acpi_device object with LNXVIDEO ‘bus_id’ will be created for it.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1jhhhKhjubah}(h]h ]h"]h$]h&]uh1jJhjubeh}(h]h ]h"]h$]h&]uh1j4hhhMhj1ubeh}(h]h ]h"]h$]h&]uh1j/hj+ubah}(h]h ]h"]h$]h&]uh1jhhhKhjhhubj)}(hThe third column of the above table indicates which ACPI System Description Tables contain information used for the creation of the struct acpi_device objects represented by the given row (xSDT means DSDT or SSDT).h]hThe third column of the above table indicates which ACPI System Description Tables contain information used for the creation of the struct acpi_device objects represented by the given row (xSDT means DSDT or SSDT).}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1jhhhMhjhhubj)}(hmThe fourth column of the above table indicates the 'bus_id' generation rule of the struct acpi_device object:h]hqThe fourth column of the above table indicates the ‘bus_id’ generation rule of the struct acpi_device object:}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1jhhhMhjhhubj)}(hX_HID: _HID in the last column of the table means that the object's bus_id is derived from the _HID/_CID identification objects present under the corresponding ACPI namespace node. The object's sysfs directory will then contain the 'hid' and 'modalias' attributes that can be used to retrieve the _HID and _CIDs of that object. LNXxxxxx: The 'modalias' attribute is also present for struct acpi_device objects having bus_id of the "LNXxxxxx" form (pseudo devices), in which cases it contains the bus_id string itself. device: 'device' in the last column of the table indicates that the object's bus_id cannot be determined from _HID/_CID of the corresponding ACPI namespace node, although that object represents a device (for example, it may be a PCI device with _ADR defined and without _HID or _CID). In that case the string 'device' will be used as the object's bus_id. h]j0)}(hhh](j5)}(hXF_HID: _HID in the last column of the table means that the object's bus_id is derived from the _HID/_CID identification objects present under the corresponding ACPI namespace node. The object's sysfs directory will then contain the 'hid' and 'modalias' attributes that can be used to retrieve the _HID and _CIDs of that object.h](j;)}(h_HID:h]h_HID:}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1j:hhhMhjubjK)}(hhh]j)}(hX@_HID in the last column of the table means that the object's bus_id is derived from the _HID/_CID identification objects present under the corresponding ACPI namespace node. The object's sysfs directory will then contain the 'hid' and 'modalias' attributes that can be used to retrieve the _HID and _CIDs of that object.h]hXL_HID in the last column of the table means that the object’s bus_id is derived from the _HID/_CID identification objects present under the corresponding ACPI namespace node. The object’s sysfs directory will then contain the ‘hid’ and ‘modalias’ attributes that can be used to retrieve the _HID and _CIDs of that object.}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1jhhhM hj ubah}(h]h ]h"]h$]h&]uh1jJhjubeh}(h]h ]h"]h$]h&]uh1j4hhhMhjubj5)}(hLNXxxxxx: The 'modalias' attribute is also present for struct acpi_device objects having bus_id of the "LNXxxxxx" form (pseudo devices), in which cases it contains the bus_id string itself.h](j;)}(h LNXxxxxx:h]h LNXxxxxx:}(hj) hhhNhNubah}(h]h ]h"]h$]h&]uh1j:hhhMhj% ubjK)}(hhh]j)}(hThe 'modalias' attribute is also present for struct acpi_device objects having bus_id of the "LNXxxxxx" form (pseudo devices), in which cases it contains the bus_id string itself.h]hThe ‘modalias’ attribute is also present for struct acpi_device objects having bus_id of the “LNXxxxxx” form (pseudo devices), in which cases it contains the bus_id string itself.}(hj: hhhNhNubah}(h]h ]h"]h$]h&]uh1jhhhMhj7 ubah}(h]h ]h"]h$]h&]uh1jJhj% ubeh}(h]h ]h"]h$]h&]uh1j4hhhMhjubj5)}(hXedevice: 'device' in the last column of the table indicates that the object's bus_id cannot be determined from _HID/_CID of the corresponding ACPI namespace node, although that object represents a device (for example, it may be a PCI device with _ADR defined and without _HID or _CID). In that case the string 'device' will be used as the object's bus_id. h](j;)}(hdevice:h]hdevice:}(hjX hhhNhNubah}(h]h ]h"]h$]h&]uh1j:hhhMhjT ubjK)}(hhh]j)}(hX['device' in the last column of the table indicates that the object's bus_id cannot be determined from _HID/_CID of the corresponding ACPI namespace node, although that object represents a device (for example, it may be a PCI device with _ADR defined and without _HID or _CID). In that case the string 'device' will be used as the object's bus_id.h]hXg‘device’ in the last column of the table indicates that the object’s bus_id cannot be determined from _HID/_CID of the corresponding ACPI namespace node, although that object represents a device (for example, it may be a PCI device with _ADR defined and without _HID or _CID). In that case the string ‘device’ will be used as the object’s bus_id.}(hji hhhNhNubah}(h]h ]h"]h$]h&]uh1jhhhMhjf ubah}(h]h ]h"]h$]h&]uh1jJhjT ubeh}(h]h ]h"]h$]h&]uh1j4hhhMhjubeh}(h]h ]h"]h$]h&]uh1j/hjubah}(h]h ]h"]h$]h&]uh1jhhhM hjhhubeh}(h]linux-acpi-device-objectsah ]h"]linux acpi device objectsah$]h&]uh1j[hj]hhhhhKubj\)}(hhh](ja)}(hLinux ACPI Physical Device Glueh]hLinux ACPI Physical Device Glue}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1j`hj hhhhhMubj)}(hXCACPI device (i.e. struct acpi_device) objects may be linked to other objects in the Linux' device hierarchy that represent "physical" devices (for example, devices on the PCI bus). If that happens, it means that the ACPI device object is a "companion" of a device otherwise represented in a different way and is used (1) to provide configuration information on that device which cannot be obtained by other means and (2) to do specific things to the device with the help of its ACPI control methods. One ACPI device object may be linked this way to multiple "physical" devices.h]hXQACPI device (i.e. struct acpi_device) objects may be linked to other objects in the Linux’ device hierarchy that represent “physical” devices (for example, devices on the PCI bus). If that happens, it means that the ACPI device object is a “companion” of a device otherwise represented in a different way and is used (1) to provide configuration information on that device which cannot be obtained by other means and (2) to do specific things to the device with the help of its ACPI control methods. One ACPI device object may be linked this way to multiple “physical” devices.}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1jhhhM!hj hhubj)}(hXIf an ACPI device object is linked to a "physical" device, its sysfs directory contains the "physical_node" symbolic link to the sysfs directory of the target device object. In turn, the target device's sysfs directory will then contain the "firmware_node" symbolic link to the sysfs directory of the companion ACPI device object. The linking mechanism relies on device identification provided by the ACPI namespace. For example, if there's an ACPI namespace object representing a PCI device (i.e. a device object under an ACPI namespace object representing a PCI bridge) whose _ADR returns 0x00020000 and the bus number of the parent PCI bridge is 0, the sysfs directory representing the struct acpi_device object created for that ACPI namespace object will contain the 'physical_node' symbolic link to the /sys/devices/pci0000:00/0000:00:02:0/ sysfs directory of the corresponding PCI device.h]hXIf an ACPI device object is linked to a “physical” device, its sysfs directory contains the “physical_node” symbolic link to the sysfs directory of the target device object. In turn, the target device’s sysfs directory will then contain the “firmware_node” symbolic link to the sysfs directory of the companion ACPI device object. The linking mechanism relies on device identification provided by the ACPI namespace. For example, if there’s an ACPI namespace object representing a PCI device (i.e. a device object under an ACPI namespace object representing a PCI bridge) whose _ADR returns 0x00020000 and the bus number of the parent PCI bridge is 0, the sysfs directory representing the struct acpi_device object created for that ACPI namespace object will contain the ‘physical_node’ symbolic link to the /sys/devices/pci0000:00/0000:00:02:0/ sysfs directory of the corresponding PCI device.}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1jhhhM+hj hhubj)}(hX(The linking mechanism is generally bus-specific. The core of its implementation is located in the drivers/acpi/glue.c file, but there are complementary parts depending on the bus types in question located elsewhere. For example, the PCI-specific part of it is located in drivers/pci/pci-acpi.c.h]hX(The linking mechanism is generally bus-specific. The core of its implementation is located in the drivers/acpi/glue.c file, but there are complementary parts depending on the bus types in question located elsewhere. For example, the PCI-specific part of it is located in drivers/pci/pci-acpi.c.}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1jhhhM:hj hhubeh}(h]linux-acpi-physical-device-glueah ]h"]linux acpi physical device glueah$]h&]uh1j[hj]hhhhhMubj\)}(hhh](ja)}(hExample Linux ACPI Device Treeh]hExample Linux ACPI Device Tree}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1j`hj hhhhhMBubj)}(hThe sysfs hierarchy of struct acpi_device objects corresponding to the example ACPI namespace illustrated in Figure 2 with the addition of fixed PWR_BUTTON/SLP_BUTTON devices is shown below::h]hThe sysfs hierarchy of struct acpi_device objects corresponding to the example ACPI namespace illustrated in Figure 2 with the addition of fixed PWR_BUTTON/SLP_BUTTON devices is shown below:}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1jhhhMDhj hhubj)}(hX +--------------+---+-----------------+ | LNXSYSTM:00 | \ | acpi:LNXSYSTM: | +--------------+---+-----------------+ | | +-------------+-----+----------------+ +-| LNXPWRBN:00 | N/A | acpi:LNXPWRBN: | | +-------------+-----+----------------+ | | +-------------+-----+----------------+ +-| LNXSLPBN:00 | N/A | acpi:LNXSLPBN: | | +-------------+-----+----------------+ | | +-----------+------------+--------------+ +-| LNXCPU:00 | \_PR_.CPU0 | acpi:LNXCPU: | | +-----------+------------+--------------+ | | +-------------+-------+----------------+ +-| LNXSYBUS:00 | \_SB_ | acpi:LNXSYBUS: | | +-------------+-------+----------------+ | | | | +- - - - - - - +- - - - - - +- - - - - - - -+ | +-| PNP0C0D:00 | \_SB_.LID0 | acpi:PNP0C0D: | | | +- - - - - - - +- - - - - - +- - - - - - - -+ | | | | +------------+------------+-----------------------+ | +-| PNP0A08:00 | \_SB_.PCI0 | acpi:PNP0A08:PNP0A03: | | +------------+------------+-----------------------+ | | | | +-----------+-----------------+-----+ | +-| device:00 | \_SB_.PCI0.RP03 | N/A | | | +-----------+-----------------+-----+ | | | | | | +-------------+----------------------+----------------+ | | +-| LNXPOWER:00 | \_SB_.PCI0.RP03.PXP3 | acpi:LNXPOWER: | | | +-------------+----------------------+----------------+ | | | | +-------------+-----------------+----------------+ | +-| LNXVIDEO:00 | \_SB_.PCI0.GFX0 | acpi:LNXVIDEO: | | +-------------+-----------------+----------------+ | | | | +-----------+-----------------+-----+ | +-| device:01 | \_SB_.PCI0.DD01 | N/A | | +-----------+-----------------+-----+ | | +-------------+-------+----------------+ +-| LNXSYBUS:01 | \_TZ_ | acpi:LNXSYBUS: | +-------------+-------+----------------+ | | +-------------+------------+----------------+ +-| LNXPOWER:0a | \_TZ_.FN00 | acpi:LNXPOWER: | | +-------------+------------+----------------+ | | +------------+------------+---------------+ +-| PNP0C0B:00 | \_TZ_.FAN0 | acpi:PNP0C0B: | | +------------+------------+---------------+ | | +-------------+------------+----------------+ +-| LNXTHERM:00 | \_TZ_.TZ00 | acpi:LNXTHERM: | +-------------+------------+----------------+ Figure 3. Example Linux ACPI Device Treeh]hX +--------------+---+-----------------+ | LNXSYSTM:00 | \ | acpi:LNXSYSTM: | +--------------+---+-----------------+ | | +-------------+-----+----------------+ +-| LNXPWRBN:00 | N/A | acpi:LNXPWRBN: | | +-------------+-----+----------------+ | | +-------------+-----+----------------+ +-| LNXSLPBN:00 | N/A | acpi:LNXSLPBN: | | +-------------+-----+----------------+ | | +-----------+------------+--------------+ +-| LNXCPU:00 | \_PR_.CPU0 | acpi:LNXCPU: | | +-----------+------------+--------------+ | | +-------------+-------+----------------+ +-| LNXSYBUS:00 | \_SB_ | acpi:LNXSYBUS: | | +-------------+-------+----------------+ | | | | +- - - - - - - +- - - - - - +- - - - - - - -+ | +-| PNP0C0D:00 | \_SB_.LID0 | acpi:PNP0C0D: | | | +- - - - - - - +- - - - - - +- - - - - - - -+ | | | | +------------+------------+-----------------------+ | +-| PNP0A08:00 | \_SB_.PCI0 | acpi:PNP0A08:PNP0A03: | | +------------+------------+-----------------------+ | | | | +-----------+-----------------+-----+ | +-| device:00 | \_SB_.PCI0.RP03 | N/A | | | +-----------+-----------------+-----+ | | | | | | +-------------+----------------------+----------------+ | | +-| LNXPOWER:00 | \_SB_.PCI0.RP03.PXP3 | acpi:LNXPOWER: | | | +-------------+----------------------+----------------+ | | | | +-------------+-----------------+----------------+ | +-| LNXVIDEO:00 | \_SB_.PCI0.GFX0 | acpi:LNXVIDEO: | | +-------------+-----------------+----------------+ | | | | +-----------+-----------------+-----+ | +-| device:01 | \_SB_.PCI0.DD01 | N/A | | +-----------+-----------------+-----+ | | +-------------+-------+----------------+ +-| LNXSYBUS:01 | \_TZ_ | acpi:LNXSYBUS: | +-------------+-------+----------------+ | | +-------------+------------+----------------+ +-| LNXPOWER:0a | \_TZ_.FN00 | acpi:LNXPOWER: | | +-------------+------------+----------------+ | | +------------+------------+---------------+ +-| PNP0C0B:00 | \_TZ_.FAN0 | acpi:PNP0C0B: | | +------------+------------+---------------+ | | +-------------+------------+----------------+ +-| LNXTHERM:00 | \_TZ_.TZ00 | acpi:LNXTHERM: | +-------------+------------+----------------+ Figure 3. Example Linux ACPI Device Tree}hj sbah}(h]h ]h"]h$]h&]hhuh1jhhhMHhj hhubj)}(hXtEach node is represented as "object/path/modalias", where: 1. 'object' is the name of the object's directory in sysfs. 2. 'path' is the ACPI namespace path of the corresponding ACPI namespace object, as returned by the object's 'path' sysfs attribute. 3. 'modalias' is the value of the object's 'modalias' sysfs attribute (as described earlier in this document).h](j)}(h:Each node is represented as "object/path/modalias", where:h]h>Each node is represented as “object/path/modalias”, where:}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1jhhhMhj ubj)}(hhh](j)}(h8'object' is the name of the object's directory in sysfs.h]j)}(hj h]h>‘object’ is the name of the object’s directory in sysfs.}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1jhhhMhj ubah}(h]h ]h"]h$]h&]uh1jhj ubj)}(h'path' is the ACPI namespace path of the corresponding ACPI namespace object, as returned by the object's 'path' sysfs attribute.h]j)}(h'path' is the ACPI namespace path of the corresponding ACPI namespace object, as returned by the object's 'path' sysfs attribute.h]h‘path’ is the ACPI namespace path of the corresponding ACPI namespace object, as returned by the object’s ‘path’ sysfs attribute.}(hj7 hhhNhNubah}(h]h ]h"]h$]h&]uh1jhhhMhj3 ubah}(h]h ]h"]h$]h&]uh1jhj ubj)}(hk'modalias' is the value of the object's 'modalias' sysfs attribute (as described earlier in this document).h]j)}(hk'modalias' is the value of the object's 'modalias' sysfs attribute (as described earlier in this document).h]hu‘modalias’ is the value of the object’s ‘modalias’ sysfs attribute (as described earlier in this document).}(hjO hhhNhNubah}(h]h ]h"]h$]h&]uh1jhhhMhjK ubah}(h]h ]h"]h$]h&]uh1jhj ubeh}(h]h ]h"]h$]h&]jjjhjjuh1jhj ubeh}(h]h ]h"]h$]h&]uh1jhj hhhNhNubj)}(hUN/A indicates the device object does not have the 'path' or the 'modalias' attribute.h]j)}(hUN/A indicates the device object does not have the 'path' or the 'modalias' attribute.h]h]N/A indicates the device object does not have the ‘path’ or the ‘modalias’ attribute.}(hjs hhhNhNubah}(h]h ]h"]h$]h&]uh1jhhhMhjo ubah}(h]h ]h"]h$]h&]uh1jhj hhhhhNubeh}(h]example-linux-acpi-device-treeah ]h"]example linux acpi device treeah$]h&]uh1j[hj]hhhhhMBubeh}(h]1acpi-device-tree-representation-of-acpi-namespaceah ]h"]3acpi device tree - representation of acpi namespaceah$]h&]uh1j[hhhhhhhKubeh}(h]h ]h"]h$]h&]sourcehuh1hcurrent_sourceN current_lineNsettingsdocutils.frontendValues)}(j`N generatorN datestampN source_linkN source_urlN toc_backlinksentryfootnote_backlinksK sectnum_xformKstrip_commentsNstrip_elements_with_classesN strip_classesN report_levelK halt_levelKexit_status_levelKdebugNwarning_streamN tracebackinput_encoding utf-8-siginput_encoding_error_handlerstrictoutput_encodingutf-8output_encoding_error_handlerj error_encodingutf-8error_encoding_error_handlerbackslashreplace language_codeenrecord_dependenciesNconfigN id_prefixhauto_id_prefixid dump_settingsNdump_internalsNdump_transformsNdump_pseudo_xmlNexpose_internalsNstrict_visitorN_disable_configN_sourcehnj _destinationN _config_files]7/var/lib/git/docbuild/linux/Documentation/docutils.confafile_insertion_enabled raw_enabledKline_length_limitM'pep_referencesN pep_base_urlhttps://peps.python.org/pep_file_url_templatepep-%04drfc_referencesN rfc_base_url&https://datatracker.ietf.org/doc/html/ tab_widthKtrim_footnote_reference_spacesyntax_highlightlong smart_quotessmartquotes_locales]character_level_inline_markupdoctitle_xform docinfo_xformKsectsubtitle_xform image_loadinglinkembed_stylesheetcloak_email_addressessection_self_linkenvNubreporterNindirect_targets]substitution_defs}(hhjhjjj jj/j#j>j2jMjAj\jPjkj_jzjnjj}jjjjjjjjjjjjjjjjjjjjj.j"j=j1jLj@j[jOjjj^jyjmjj|jjjjjjjjjjjjjjjjjjjjj-j!j<j0jKj?jZjNjij]jxjljj{jjjjjjjjjjjjjjjjjjjjj,j j;j/jJj>jYjMjhj\jwjkjjzjjjjjjjjjjjjjjjjj jjjj+jj:j.jIj=jXjLusubstitution_names}(amphaposjastjbrvbarj bsolj/centj>colonjMcommaj\commatjkcopyjzcurrenjdarrjdegjdividejdollarjequalsjexcljfrac12jfrac14jfrac18jfrac34jfrac38j.frac58j=frac78jLgtj[halfjjhorbarjyhyphenjiexcljiquestjlaquojlarrjlcubjldquojlowbarjlparjlsqbjlsquojltj-microj<middotjKnbspjZnotjinumjxohmjordfjordmjparajpercntjperiodjplusjplusmnjpoundjquestjquotjraquoj,rarrj;rcubjJrdquojYregjhrparjwrsqbjrsquojsectjsemijshyjsoljsungjsup1jsup2jsup3j timesjtradej+uarrj:verbarjIyenjXurefnames}refids}nameids}(j j jjjjjjj j j j j j u nametypes}(j jjjj j j uh}(j j]jjRjjjjj jj j j j u footnote_refs} citation_refs} autofootnotes]autofootnote_refs]symbol_footnotes]symbol_footnote_refs] footnotes] citations]autofootnote_startKsymbol_footnote_startK id_counter collectionsCounter}Rparse_messages]transform_messagesr] transformerN include_log]/Documentation/firmware-guide/acpi/namespace.rst(NNNNta decorationNhhub.