Re: [PATCH] ARM64: ACPI: Update documentation for latest specification version

Al Stone
2016-02-26T21:28:43Z

On 02/20/2016 01:47 PM, Abdulhamid, Harb wrote:
> On 2/19/2016 6:54 PM, al.stone@linaro.org wrote:
>> From: Al Stone <al.stone@linaro.org>
>>
>> The ACPI 6.1 specification was recently released at the end of January 2016,
>> but the arm64 kernel documentation for the use of ACPI was written for the
>> 5.1 version of the spec. There were significant additions to the spec that
>> had not yet been mentioned -- for example, the 6.0 mechanisms added to make
>> it easier to define processors and low power idle states, as well as the
>> 6.1 addition allowing regular interrupts (not just from GPIO) be used to
>> signal ACPI general purpose events.
>>
>> This patch reflects going back through and examining the specs in detail
>> and updating content appropriately. Whilst there, a few odds and ends of
>> typos were caught as well. This brings the documentation up to date with
>> ACPI 6.1 for arm64.
>>
>> Signed-off-by: Al Stone <al.stone@linaro.org>
>> ---
>> Documentation/arm64/acpi_object_usage.txt | 433 ++++++++++++++++++++++--------
>> Documentation/arm64/arm-acpi.txt | 28 +-
>> 2 files changed, 346 insertions(+), 115 deletions(-)
>>
>> diff --git a/Documentation/arm64/acpi_object_usage.txt b/Documentation/arm64/acpi_object_usage.txt
>> index a6e1a18..e321235 100644
>> --- a/Documentation/arm64/acpi_object_usage.txt
>> +++ b/Documentation/arm64/acpi_object_usage.txt
>> @@ -13,13 +13,14 @@ For ACPI on arm64, tables also fall into the following categories:
>>
>> -- Required: DSDT, FADT, GTDT, MADT, MCFG, RSDP, SPCR, XSDT
>>
>> - -- Recommended: BERT, EINJ, ERST, HEST, SSDT
>> + -- Recommended: BERT, EINJ, ERST, HEST, IORT, PCCT, SSDT
>>
>> - -- Optional: BGRT, CPEP, CSRT, DRTM, ECDT, FACS, FPDT, MCHI, MPST,
>> - MSCT, RASF, SBST, SLIT, SPMI, SRAT, TCPA, TPM2, UEFI
>> + -- Optional: BGRT, CPEP, CSRT, DBG2, DRTM, ECDT, FACS, FPDT, MCHI,
>> + MPST, MSCT, NFIT, PMTT, RASF, SBST, SLIT, SPMI, SRAT, STAO, TCPA,
>> + TPM2, UEFI, XENV
>
> Unintended tabs? Alignment is off in my viewer.

Probably. I'll touch that up for v2.

>>
>> - -- Not supported: BOOT, DBG2, DBGP, DMAR, ETDT, HPET, IBFT, IVRS,
>> - LPIT, MSDM, RSDT, SLIC, WAET, WDAT, WDRT, WPBT
>> + -- Not supported: BOOT, DBGP, DMAR, ETDT, HPET, IBFT, IVRS, LPIT,
>> + MSDM, OEMx, PSDT, RSDT, SLIC, WAET, WDAT, WDRT, WPBT
>>
>>
>> Table Usage for ARMv8 Linux
>> @@ -50,7 +51,9 @@ CSRT Signature Reserved (signature == "CSRT")
>>
>> DBG2 Signature Reserved (signature == "DBG2")
>> == DeBuG port table 2 ==
>> - Microsoft only table, will not be supported.
>> + License has changed and should be usable. Patches are available as of
>> + this writing, but they have not been accepted into the kernel. Optional
>> + if used instead of earlycon=<device> on the command line.
>>
>> DBGP Signature Reserved (signature == "DBGP")
>> == DeBuG Port table ==
>> @@ -133,10 +136,11 @@ GTDT Section 5.2.24 (signature == "GTDT")
>>
>> HEST Section 18.3.2 (signature == "HEST")
>> == Hardware Error Source Table ==
>> - Until further error source types are defined, use only types 6 (AER
>> - Root Port), 7 (AER Endpoint), 8 (AER Bridge), or 9 (Generic Hardware
>> - Error Source). Firmware first error handling is possible if and only
>> - if Trusted Firmware is being used on arm64.
>> + ARM-specific error sources have been defined; please use those or the
>> + PCI types such as type 6 (AER Root Port), 7 (AER Endpoint), or 8 (AER
>> + Bridge), or use type 9 (Generic Hardware Error Source). Firmware first
>> + error handling is possible if and only if Trusted Firmware is being
>> + used on arm64.
>>
>> Must be supplied if RAS support is provided by the platform. It
>> is recommended this table be supplied.
>> @@ -149,20 +153,26 @@ IBFT Signature Reserved (signature == "IBFT")
>> == iSCSI Boot Firmware Table ==
>> Microsoft defined table, support TBD.
>>
>> +IORT Signature Reserved (signature == "IORT")
>> + == Input Output Remapping Table ==
>> + arm64 only table, required in order to describe the SMMU and/or ITS
>> + when it is provided by the platform.
>> +
>> IVRS Signature Reserved (signature == "IVRS")
>> == I/O Virtualization Reporting Structure ==
>> x86_64 (AMD) only table, will not be supported.
>>
>> LPIT Signature Reserved (signature == "LPIT")
>> == Low Power Idle Table ==
>> - x86 only table as of ACPI 5.1; future versions have been adapted for
>> - use with ARM and will be recommended in order to support ACPI power
>> - management.
>> + x86 only table as of ACPI 5.1; starting with ACPI 6.0, processor
>> + descriptions and power states on ARM platforms should use the DSDT
>> + and define processor container devices (_HID ACPI0010, Section 8.4,
>> + and more specifically 8.4.3 and and 8.4.4).
>>
>> MADT Section 5.2.12 (signature == "APIC")
>> == Multiple APIC Description Table ==
>> Required for arm64. Only the GIC interrupt controller structures
>> - should be used (types 0xA - 0xE).
>> + should be used (types 0xA - 0xF).
>>
>> MCFG Signature Reserved (signature == "MCFG")
>> == Memory-mapped ConFiGuration space ==
>> @@ -176,14 +186,38 @@ MPST Section 5.2.21 (signature == "MPST")
>> == Memory Power State Table ==
>> Optional, not currently supported.
>>
>> +MSCT Section 5.2.19 (signature == "MSCT")
>> + == Maximum System Characteristic Table ==
>> + Optional, not currently supported.
>> +
>> MSDM Signature Reserved (signature == "MSDM")
>> == Microsoft Data Management table ==
>> Microsoft only table, will not be supported.
>>
>> -MSCT Section 5.2.19 (signature == "MSCT")
>> - == Maximum System Characteristic Table ==
>> +NFIT Section 5.2.25 (signature == "NFIT")
>> + == NVDIMM Firmware Interface Table ==
>> Optional, not currently supported.
>>
>> +OEMx Signature of "OEMx" only
>> + == OEM Specific Tables ==
>> + All tables starting with a signature of "OEM" are reserved for OEM
>> + use. Since these are not meant to be of general use but are limited
>> + to very specific end users, they are not recommended for use and are
>> + not supported by the kernel for arm64.
>> +
>> +PCCT Section 14.1 (signature == "PCCT)
>> + == Platform Communications Channel Table ==
>> + Recommend for use on arm64, and required when using CPPC to control
>> + power on the platform.
>> +
>> +PMTT Section 5.2.21.12 (signature == "PMTT")
>> + == Platform Memory Topology Table ==
>> + Optional, but useful, but not currently supported.
>> +
>> +PSDT Section 5.2.11.3 (signature == "PSDT")
>> + == Persistent System Description Table ==
>> + Obsolete table, will not be supported.
>> +
>> RASF Section 5.2.20 (signature == "RASF")
>> == RAS Feature table ==
>> Optional, not currently supported.
>> @@ -195,7 +229,7 @@ RSDP Section 5.2.5 (signature == "RSD PTR")
>> RSDT Section 5.2.7 (signature == "RSDT")
>> == Root System Description Table ==
>> Since this table can only provide 32-bit addresses, it is deprecated
>> - on arm64, and will not be used.
>> + on arm64, and will not be used. If provided, it will be ignored.
>>
>> SBST Section 5.2.14 (signature == "SBST")
>> == Smart Battery Subsystem Table ==
>> @@ -207,7 +241,7 @@ SLIC Signature Reserved (signature == "SLIC")
>>
>> SLIT Section 5.2.17 (signature == "SLIT")
>> == System Locality distance Information Table ==
>> - Optional in general, but required for NUMA systems.
>> + Optional in general, but required for arm64 NUMA systems.
>>
>> SPCR Signature Reserved (signature == "SPCR")
>> == Serial Port Console Redirection table ==
>> @@ -220,7 +254,7 @@ SPMI Signature Reserved (signature == "SPMI")
>> SRAT Section 5.2.16 (signature == "SRAT")
>> == System Resource Affinity Table ==
>> Optional, but if used, only the GICC Affinity structures are read.
>> - To support NUMA, this table is required.
>> + To support arm64 NUMA, this table is required.
>>
>> SSDT Section 5.2.11.2 (signature == "SSDT")
>> == Secondary System Description Table ==
>> @@ -235,6 +269,11 @@ SSDT Section 5.2.11.2 (signature == "SSDT")
>> These tables are optional, however. ACPI tables should contain only
>> one DSDT but can contain many SSDTs.
>>
>> +STAO Signature Reserved (signature == "STAO")
>> + == _STA Override table ==
>> + Optional, but only necessary in virtualized environments in order to
>> + hide devices from guest OSs.
>> +
>> TCPA Signature Reserved (signature == "TCPA")
>> == Trusted Computing Platform Alliance table ==
>> Optional, not currently supported, and may need changes to fully
>> @@ -266,6 +305,10 @@ WPBT Signature Reserved (signature == "WPBT")
>> == Windows Platform Binary Table ==
>> Microsoft only table, will not be supported.
>>
>> +XENV Signature Reserved (signature == "XENV")
>> + == Xen project table ==
>> + Optional, used only by Xen at present.
>> +
>> XSDT Section 5.2.8 (signature == "XSDT")
>> == eXtended System Description Table ==
>> Required for arm64.
>> @@ -273,31 +316,50 @@ XSDT Section 5.2.8 (signature == "XSDT")
>>
>> ACPI Objects
>> ------------
>> -The expectations on individual ACPI objects are discussed in the list that
>> -follows:
>> +The expectations on individual ACPI objects that are likely to be used are
>> +shown in the list that follows:
>>
>> Name Section Usage for ARMv8 Linux
>> ---- ------------ -------------------------------------------------
>> +_ACx 11.4.1 Use as needed.
>> +
>> _ADR 6.1.1 Use as needed.
>>
>> +_ALx 11.4.2 Use as needed.
>> +
>> +_ART 11.4.3 Use as needed.
>> +
>> _BBN 6.5.5 Use as needed; PCI-specific.
>>
>> -_BDN 6.5.3 Optional; not likely to be used on arm64.
>> +_CCA 6.2.17 This method must be defined for all bus masters
>> + on arm64 -- there are no assumptions made about
>> + whether such devices are cache coherent or not.
>> + The _CCA value is inherited by all descendants of
>> + these devices so it does not need to be repeated.
>> + Without _CCA on arm64, the kernel does not know what
>> + to do about setting up DMA for the device.
>> +
> Alignment issue again.

Thanks for catching that. My bad.

> I would also add the following clarification to this (maybe not as verbose):
> Note that CCA provides the default cache coherent attributes, however
> the presence of an SMMU could potentially be used to modify bus
> attributes. For example, if a master defaults to non-coherent, it could
> be made coherent with the appropriate SMMU configuration. Please refer
> to Table 17 of the IORT specification (Document Number: ARM DEN 0049B)
> for more information.

Ah, good point. I'll add this and try to trim it down a bit.

>> +_CDM 6.2.1 Use as needed, to be used only for processor devices.
>>
>> -_CCA 6.2.17 This method should be defined for all bus masters
>> - on arm64. While cache coherency is assumed, making
>> - it explicit ensures the kernel will set up DMA as
>> - it should.
>> +_CID 6.1.2 Use as needed, see also _HID.
>>
>> -_CDM 6.2.1 Optional, to be used only for processor devices.
>> +_CLS 6.1.3 Use as needed, see also _HID.
>>
>> -_CID 6.1.2 Use as needed.
>> +_CPC 8.4.7.1 Use as needed; power management specific. CPPC is
>> + recommended on arm64.
>>
>> -_CLS 6.1.3 Use as needed.
>> +_CR3 11.4.5 Use as needed.
>>
>> _CRS 6.2.2 Required on arm64.
>>
>> -_DCK 6.5.2 Optional; not likely to be used on arm64.
>> +_CRT 11.4.4 Use as needed.
>> +
>> +_CSD 8.4.2.2 Use as needed, used only in conjuction with _CST.
>> +
>> +_CST 8.4.2.1 Low power idle states (8.4.4) are recommended instead
>> + of C-states.
>> +
>> +_CWS 9.18.6 Use as needed.
>>
>> _DDN 6.1.4 This field can be used for a device name. However,
>> it is meant for DOS device names (e.g., COM1), so be
>> @@ -305,11 +367,11 @@ _DDN 6.1.4 This field can be used for a device name. However,
>>
>> _DEP 6.5.8 Use as needed.
>>
>> -_DIS 6.2.3 Optional, for power management use.
>> +_DIS 6.2.3 Use as needed, for power management use.
>>
>> -_DLM 5.7.5 Optional.
>> +_DLM 5.7.5 Use as needed.
>>
>> -_DMA 6.2.4 Optional.
>> +_DMA 6.2.4 Use as needed.
>>
>> _DSD 6.2.5 To be used with caution. If this object is used, try
>> to use it within the constraints already defined by the
>> @@ -325,19 +387,29 @@ _DSD 6.2.5 To be used with caution. If this object is used, try
>> with the UEFI Forum; this may cause some iteration as
>> more than one OS will be registering entries.
>>
>> -_DSM Do not use this method. It is not standardized, the
>> +_DSM 9.1.1 Do not use this method. It is not standardized, the
>> return values are not well documented, and it is
>> currently a frequent source of error.
>>
>> -_DSW 7.2.1 Use as needed; power management specific.
>> +_DSW 7.3.1 Use as needed; power management specific.
>>
>> -_EDL 6.3.1 Optional.
>> +_DTI 11.4.6 Use as needed.
>>
>> -_EJD 6.3.2 Optional.
>> +_EDL 6.3.1 Use as needed.
>>
>> -_EJx 6.3.3 Optional.
>> +_EJD 6.3.2 Use as needed.
>>
>> -_FIX 6.2.7 x86 specific, not used on arm64.
>> +_EJx 6.3.3 Use as needed.
>> +
>> +_FIF 11.3.1.1 Use as needed.
>> +
>> +_FPS 11.3.1.2 Use as needed.
>> +
>> +_FSL 11.3.1.3 Use as needed.
>> +
>> +_FST 11.3.1.4 Use as needed.
>> +
>> +_GCP 9.18.2 Use as needed.
>>
>> \_GL 5.7.1 This object is not to be used in hardware reduced
>> mode, and therefore should not be used on arm64.
>> @@ -349,35 +421,56 @@ _GLK 6.5.7 This object requires a global lock be defined; there
>> \_GPE 5.3.1 This namespace is for x86 use only. Do not use it
>> on arm64.
>>
>> -_GSB 6.2.7 Optional.
>> +_GRT 9.18.3 Use as needed.
>> +
>> +_GSB 6.2.7 Use as needed.
>> +
>> +_GTF 9.9.1.1 Use as needed.
>> +
>> +_GWS 9.18.5 Use as needed.
>>
>> _HID 6.1.5 Use as needed. This is the primary object to use in
>> device probing, though _CID and _CLS may also be used.
>>
>> -_HPP 6.2.8 Optional, PCI specific.
>> +_HOT 11.4.7 Use as needed.
>> +
>> +_HPP 6.2.8 Use as needed, PCI specific.
>>
>> -_HPX 6.2.9 Optional, PCI specific.
>> +_HPX 6.2.9 Use as needed, PCI specific.
>>
>> -_HRV 6.1.6 Optional, use as needed to clarify device behavior; in
>> +_HRV 6.1.6 Use as needed, use as needed to clarify device behavior; in
>> some cases, this may be easier to use than _DSD.
>>
>> _INI 6.5.1 Not required, but can be useful in setting up devices
>> when UEFI leaves them in a state that may not be what
>> the driver expects before it starts probing.
>>
>> -_IRC 7.2.15 Use as needed; power management specific.
>> +_IRC 7.3.15 Use as needed; power management specific.
>> +
>> +_LCK 6.3.4 Use as needed.
>> +
>> +_LPI 8.4.4.3 Use as needed, but recommended for use with processor
>> + definitions (_HID ACPI0010) on arm64.
>>
>> -_LCK 6.3.4 Optional.
>> +_MAT 6.2.10 Use as needed; see also the MADT.
>>
>> -_MAT 6.2.10 Optional; see also the MADT.
>> +_MBM 9.13.2.1 Use as needed.
>>
>> -_MLS 6.1.7 Optional, but highly recommended for use in
>> +_MLS 6.1.7 Use as needed, but highly recommended for use in
>> internationalization.
>>
>> -_OFF 7.1.2 It is recommended to define this method for any device
>> +_MSG 9.2.2 Use as needed.
>> +
>> +_MSM 9.13.2.2 Use as needed.
>> +
>> +_MTL 11.4.8 Use as needed.
>> +
>> +_NTT 11.4.9 Use as needed.
>> +
>> +_OFF 7.2.2 It is recommended to define this method for any device
>> that can be turned on or off.
>>
>> -_ON 7.1.3 It is recommended to define this method for any device
>> +_ON 7.2.3 It is recommended to define this method for any device
>> that can be turned on or off.
>>
>> \_OS 5.7.3 This method will return "Linux" by default (this is
>> @@ -405,115 +498,219 @@ _OSC 6.2.11 This method can be a global method in ACPI (i.e.,
>> being used or what functionality is provided. The
>> _OSC method is to be used instead.
>>
>> -_OST 6.3.5 Optional.
>> +_OST 6.3.5 Use as needed.
>> +
>> +_PCT 8.4.6.1 Use as needed; power management specific.
>>
>> _PDC 8.4.1 Deprecated, do not use on arm64.
>>
>> +_PDL 8.4.6.2 Use as needed; power management specific.
>> +
>> \_PIC 5.8.1 The method should not be used. On arm64, the only
>> interrupt model available is GIC.
>>
>> -_PLD 6.1.8 Optional.
>> +_PLD 6.1.8 Use as needed.
>> +
>> +_PPC 8.4.6.3 Use as needed; power management specific.
>> +
>> +_PPE 8.4.8 Use as needed.
>>
>> \_PR 5.3.1 This namespace is for x86 use only on legacy systems.
>> Do not use it on arm64.
>>
>> -_PRS 6.2.12 Optional.
>> +_PRE 7.3.12 Use as needed; power management specific.
>> +
>> +_PRR 7.3.26 Use as needed; power management specific.
>> +
>> +_PRS 6.2.12 Use as needed.
>>
>> _PRT 6.2.13 Required as part of the definition of all PCI root
>> devices.
>>
>> -_PRW 7.2.13 Use as needed; power management specific.
>> +_PRW 7.3.13 Use as needed; power management specific.
>>
>> -_PRx 7.2.8-11 Use as needed; power management specific. If _PR0 is
>> +_PRx 7.3.8-11 Use as needed; power management specific. If _PR0 is
>> defined, _PR3 must also be defined.
>>
>> -_PSC 7.2.6 Use as needed; power management specific.
>> +_PSC 7.3.6 Use as needed; power management specific.
>> +
>> +_PSD 8.4.6.5 Use as needed; power management specific.
>>
>> -_PSE 7.2.7 Use as needed; power management specific.
>> +_PSE 7.3.7 Use as needed; power management specific.
>>
>> -_PSW 7.2.14 Use as needed; power management specific.
>> +_PSL 11.4.10 Use as needed.
>>
>> -_PSx 7.2.2-5 Use as needed; power management specific. If _PS0 is
>> +_PSS 8.4.6.2 Use as needed; power management specific.
>> +
>> +_PSV 11.4.11 Use as needed.
>> +
>> +_PSW 7.3.14 Use as needed; power management specific.
>> +
>> +_PSx 7.3.2-5 Use as needed; power management specific. If _PS0 is
>> defined, _PS3 must also be defined. If clocks or
>> regulators need adjusting to be consistent with power
>> usage, change them in these methods.
>>
>> -\_PTS 7.3.1 Use as needed; power management specific.
>> +_PTC 8.4.5.1 Use as needed; power management specific.
>> +
>> +\_PTS 7.4.1 Use as needed; power management specific.
>> +
>> +_PUR 8.5.1.1 Use as needed.
>> +
>> +_PXM 6.2.14 Use as needed.
>>
>> -_PXM 6.2.14 Optional.
>> +_RDI 8.4.4.4 Use as needed, but recommended for use with processor
>> + definitions (_HID ACPI0010) on arm64.
>>
>> _REG 6.5.4 Use as needed.
>>
>> \_REV 5.7.4 Always returns the latest version of ACPI supported.
>>
>> -_RMV 6.3.6 Optional.
>> +_RMV 6.3.6 Use as needed.
>> +
>> +_RST 7.3.25 Use as needed; power management specific.
>> +
>> +_RTV 11.4.12 Use as needed.
>>
>> \_SB 5.3.1 Required on arm64; all devices must be defined in this
>> namespace.
>>
>> +_SCP 11.4.13 Use as needed.
>> +
>> +_SDD 9.9.3.3.1 Use as needed.
>> +
>> _SEG 6.5.6 Use as needed; PCI-specific.
>>
>> -\_SI 5.3.1, Optional.
>> - 9.1
>> +\_SI 5.3.1, Use as needed.
>> + 9.2
>> +
>> +_SLI 6.2.15 Use as needed; recommended when SLIT table is in use.
>>
>> -_SLI 6.2.15 Optional; recommended when SLIT table is in use.
>> +_SRT 9.18.4 Use as needed.
>>
>> _STA 6.3.7, It is recommended to define this method for any device
>> - 7.1.4 that can be turned on or off.
>> + 7.2.4 that can be turned on or off. See also the STAO table
>> + that provides overrides to hide devices in virtualized
>> + environments.
> Alignment issue again.

Bah. Thanks for catching it. Will fix.

>>
>> -_SRS 6.2.16 Optional; see also _PRS.
>> +_SRS 6.2.16 Use as needed; see also _PRS.
>> +
>> +_SST 9.2.1 Use as needed.
>>
>> _STR 6.1.10 Recommended for conveying device names to end users;
>> this is preferred over using _DDN.
>>
>> +_SST 9.2.1 Use as needed.
>> +
>> +_STP 9.18.7 Use as needed.
>> +
>> +_STV 9.18.8 Use as needed.
>> +
>> _SUB 6.1.9 Use as needed; _HID or _CID are preferred.
>>
>> -_SUN 6.1.11 Optional.
>> +_SUN 6.1.11 Use as needed, but recommended.
>>
>> -\_Sx 7.3.2 Use as needed; power management specific.
>> +\_Sx 7.4.2 Use as needed; power management specific.
>>
>> -_SxD 7.2.16-19 Use as needed; power management specific.
>> +_SxD 7.3.16-19 Use as needed; power management specific.
>>
>> -_SxW 7.2.20-24 Use as needed; power management specific.
>> +_SxW 7.3.20-24 Use as needed; power management specific.
>>
>> -_SWS 7.3.3 Use as needed; power management specific; this may
>> +_SWS 7.4.3 Use as needed; power management specific; this may
>> require specification changes for use on arm64.
>>
>> -\_TTS 7.3.4 Use as needed; power management specific.
>> +_TC1 11.4.14 Use as needed.
>> +
>> +_TC2 11.4.15 Use as needed.
>> +
>> +_TDL 8.4.5.5 Use as needed; power management specific.
>> +
>> +_TFP 11.4.16 Use as needed.
>> +
>> +_TIP 9.18.9 Use as needed.
>> +
>> +_TIV 9.18.10 Use as needed.
>> +
>> +_TMP 11.4.17 Use as needed.
>> +
>> +_TPC 8.4.5.3 Use as needed; power management specific.
>>
>> -\_TZ 5.3.1 Optional.
>> +_TPT 11.4.18 Use as needed.
>> +
>> +_TRT 11.4.19 Use as needed.
>> +
>> +_TSD 8.4.5.4 Use as needed; power management specific.
>> +
>> +_TSN 11.4.20 Use as needed.
>> +
>> +_TSP 11.4.21 Use as needed.
>> +
>> +_TSS 8.4.5.2 Use as needed; power management specific.
>> +
>> +_TST 11.4.22 Use as needed.
>> +
>> +\_TTS 7.4.4 Use as needed; power management specific.
>> +
>> +\_TZ 5.3.1 Use as needed.
>> +
>> +_TZD 11.4.23 Use as needed.
>> +
>> +_TZM 11.4.24 Use as needed.
>> +
>> +_TZP 11.4.25 Use as needed.
>>
>> _UID 6.1.12 Recommended for distinguishing devices of the same
>> class; define it if at all possible.
>>
>> -\_WAK 7.3.5 Use as needed; power management specific.
>> +_UPC 9.14 Use as needed.
>> +
>> +\_WAK 7.4.5 Use as needed; power management specific.
>> +
>> +
>>
>>
>> ACPI Event Model
>> ----------------
>> Do not use GPE block devices; these are not supported in the hardware reduced
>> profile used by arm64. Since there are no GPE blocks defined for use on ARM
>> -platforms, GPIO-signaled interrupts should be used for creating system events.
>> +platforms, ACPI events must be signaled differently.
>> +
>> +There are two options: GPIO-signaled interrupts (Section 5.6.5), and
>> +interrupt-signaled events (Section 5.6.9). Interrupt-signaled events are a
>> +new feature in the ACPI 6.1 specification. Either -- or both -- can be used
>> +on a given platform, and which to use may be dependent of limitations in any
>> +given SoC. If possible, interrupt-signaled events are recommended.
>>
>>
>> ACPI Processor Control
>> ----------------------
>> -Section 8 of the ACPI specification is currently undergoing change that
>> -should be completed in the 6.0 version of the specification. Processor
>> -performance control will be handled differently for arm64 at that point
>> -in time. Processor aggregator devices (section 8.5) will not be used,
>> -for example, but another similar mechanism instead.
>> -
>> -While UEFI constrains what we can say until the release of 6.0, it is
>> -recommended that CPPC (8.4.5) be used as the primary model. This will
>> -still be useful into the future. C-states and P-states will still be
>> -provided, but most of the current design work appears to favor CPPC.
>> +Section 8 of the ACPI specification changed significantly in version 6.0.
>> +Processors should now be defined as Device objects with _HID ACPI0007; do
>> +not use the deprecated Processor statement in ASL. All multiprocessor systems
>> +should also define a hierarchy of processors, done with Processor Container
>> +Devices (see Section 8.4.3.1, _HID ACPI0010); do not use processor aggregator
>> +devices (Section 8.5) to describe processor topology. Section 8.4 of the
>> +specification describes the semantics of these object definitions and how
>> +they interrelate.
>> +
>> +Most importantly, the processor hierarchy defined also defines the low power
>> +idle states that are available to the platform, along with the rules for
>> +determining which processors can be turned on or off and the circumstances
>> +that control that. Without this information, the processors will run in
>> +whatever power state they were left in by UEFI.
>> +
>> +Note too, that the processor Device objects defined and the entries in the
>> +MADT for GICs are expected to be in sychronization. The _UID of the Device
>> +object must correspond to processor IDs used in the MADT.
>> +
>> +It is recommended that CPPC (8.4.5) be used as the primary model for processor
>> +performance control on arm64. C-states and P-states may become available at
>> +some point in the future, but most current design work appears to favor CPPC.
>>
>> Further, it is essential that the ARMv8 SoC provide a fully functional
>> implementation of PSCI; this will be the only mechanism supported by ACPI
>> -to control CPU power state (including secondary CPU booting).
>> -
>> -More details will be provided on the release of the ACPI 6.0 specification.
>> +to control CPU power state. Booting of secondary CPUs may be possible using
>> +parking protocol, but only PSCI is to be used for ARM servers.
>>
>>
>> ACPI System Address Map Interfaces
>> @@ -535,21 +732,25 @@ used to indicate fatal errors that cannot be corrected, and require immediate
>> attention.
>>
>> Since there is no direct equivalent of the x86 SCI or NMI, arm64 handles
>> -these slightly differently. The SCI is handled as a normal GPIO-signaled
>> -interrupt; given that these are corrected (or correctable) errors being
>> -reported, this is sufficient. The NMI is emulated as the highest priority
>> -GPIO-signaled interrupt possible. This implies some caution must be used
>> -since there could be interrupts at higher privilege levels or even interrupts
>> -at the same priority as the emulated NMI. In Linux, this should not be the
>> -case but one should be aware it could happen.
>> +these slightly differently. The SCI is handled as a high priority interrupt;
>> +given that these are corrected (or correctable) errors being reported, this
>> +is sufficient. The NMI is emulated as the highest priority interrupt
>> +possible. This implies some caution must be used since there could be
>> +interrupts at higher privilege levels or even interrupts at the same priority
>> +as the emulated NMI. In Linux, this should not be the case but one should
>> +be aware it could happen.
>>
>>
>> ACPI Objects Not Supported on ARM64
>> -----------------------------------
>> While this may change in the future, there are several classes of objects
>> that can be defined, but are not currently of general interest to ARM servers.
>> +Some of these objects have x86 equivalents, and may actually make sense in ARM
>> +servers. However, there is either no hardware available at present, or there
>> +may not even be a non-ARM implementation yet. Hence, they are not currently
>> +supported.
>>
>> -These are not supported:
>> +The following classes of objects are not supported:
>>
>> -- Section 9.2: ambient light sensor devices
>>
>> @@ -571,16 +772,6 @@ These are not supported:
>>
>> -- Section 9.18: time and alarm devices (see 9.15)
>>
>> -
>> -ACPI Objects Not Yet Implemented
>> ---------------------------------
>> -While these objects have x86 equivalents, and they do make some sense in ARM
>> -servers, there is either no hardware available at present, or in some cases
>> -there may not yet be a non-ARM implementation. Hence, they are currently not
>> -implemented though that may change in the future.
>> -
>> -Not yet implemented are:
>> -
>> -- Section 10: power source and power meter devices
>>
>> -- Section 11: thermal management
>> @@ -589,5 +780,31 @@ Not yet implemented are:
>>
>> -- Section 13: SMBus interfaces
>>
>> - -- Section 17: NUMA support (prototypes have been submitted for
>> - review)
>> +
>> +This also mean that there is no support for the following objects:
>> +
>> +Name Section Name Section
>> +---- ------------ ---- ------------
>> +_ALC 9.3.4 _FDM 9.10.3
>> +_ALI 9.3.2 _FIX 6.2.7
>> +_ALP 9.3.6 _GAI 10.4.5
>> +_ALR 9.3.5 _GHL 10.4.7
>> +_ALT 9.3.3 _GTM 9.9.2.1.1
>> +_BCT 10.2.2.10 _LID 9.5.1
>> +_BDN 6.5.3 _PAI 10.4.4
>> +_BIF 10.2.2.1 _PCL 10.3.2
>> +_BIX 10.2.2.1 _PIF 10.3.3
>> +_BLT 9.2.3 _PMC 10.4.1
>> +_BMA 10.2.2.4 _PMD 10.4.8
>> +_BMC 10.2.2.12 _PMM 10.4.3
>> +_BMD 10.2.2.11 _PRL 10.3.4
>> +_BMS 10.2.2.5 _PSR 10.3.1
>> +_BST 10.2.2.6 _PTP 10.4.2
>> +_BTH 10.2.2.7 _SBS 10.1.3
>> +_BTM 10.2.2.9 _SHL 10.4.6
>> +_BTP 10.2.2.8 _STM 9.9.2.1.1
>> +_DCK 6.5.2 _UPD 9.16.1
>> +_EC 12.12 _UPP 9.16.2
>> +_FDE 9.10.1 _WPC 10.5.2
>> +_FDI 9.10.2 _WPP 10.5.3
>> +
>> diff --git a/Documentation/arm64/arm-acpi.txt b/Documentation/arm64/arm-acpi.txt
>> index 570a4f8..12381c1 100644
>> --- a/Documentation/arm64/arm-acpi.txt
>> +++ b/Documentation/arm64/arm-acpi.txt
>> @@ -57,11 +57,11 @@ The short form of the rationale for ACPI on ARM is:
>>
>> -- The new ACPI governance process works well and Linux is now at the same
>> table as hardware vendors and other OS vendors. In fact, there is no
>> - longer any reason to feel that ACPI is only belongs to Windows or that
>> + longer any reason to feel that ACPI only belongs to Windows or that
>> Linux is in any way secondary to Microsoft in this arena. The move of
>> ACPI governance into the UEFI forum has significantly opened up the
>> specification development process, and currently, a large portion of the
>> - changes being made to ACPI is being driven by Linux.
>> + changes being made to ACPI are being driven by Linux.
>>
>> Key to the use of ACPI is the support model. For servers in general, the
>> responsibility for hardware behaviour cannot solely be the domain of the
>> @@ -159,7 +159,7 @@ Further, the ACPI core will only use the 64-bit address fields in the FADT
>> (Fixed ACPI Description Table). Any 32-bit address fields in the FADT will
>> be ignored on arm64.
>>
>> -Hardware reduced mode (see Section 4.1 of the ACPI 5.1 specification) will
>> +Hardware reduced mode (see Section 4.1 of the ACPI 6.1 specification) will
>> be enforced by the ACPI core on arm64. Doing so allows the ACPI core to
>> run less complex code since it no longer has to provide support for legacy
>> hardware from other architectures. Any fields that are not to be used for
>> @@ -167,7 +167,7 @@ hardware reduced mode must be set to zero.
>>
>> For the ACPI core to operate properly, and in turn provide the information
>> the kernel needs to configure devices, it expects to find the following
>> -tables (all section numbers refer to the ACPI 5.1 specfication):
>> +tables (all section numbers refer to the ACPI 6.1 specfication):
>>
>> -- RSDP (Root System Description Pointer), section 5.2.5
>>
>> @@ -185,9 +185,22 @@ tables (all section numbers refer to the ACPI 5.1 specfication):
>> -- If PCI is supported, the MCFG (Memory mapped ConFiGuration
>> Table), section 5.2.6, specifically Table 5-31.
>>
>> + -- If booting without a console=<device> kernel parameter is
>> + supported, the SPCR (Serial Port Console Redirection table),
>> + section 5.2.6, specifically Table 5-31.
>> +
>> + -- If virtualization is supported, the IORT (Input Output Remapping
>> + Table, section 5.2.6, specifically Table 5-31.
>> +
>> + -- If NUMA is supported, the SRAT (System Resource Affinity Table)
>> + and SLIT (System Locality distance Information Table), sections
>> + 5.2.16 and 5.2.17, respectively.
>> +
>> If the above tables are not all present, the kernel may or may not be
>> able to boot properly since it may not be able to configure all of the
>> -devices available.
>> +devices available. This list of tables is not meant to be all inclusive;
>> +in some environments other tables may be needed (e.g., any of the APEI
>> +tables from section 18) to support specific functionality.
>>
>>
>> ACPI Detection
>> @@ -233,7 +246,7 @@ that looks like this: Name(KEY0, "value0"). An ACPI device driver would
>> then retrieve the value of the property by evaluating the KEY0 object.
>> However, using Name() this way has multiple problems: (1) ACPI limits
>> names ("KEY0") to four characters unlike DT; (2) there is no industry
>> -wide registry that maintains a list of names, minimzing re-use; (3)
>> +wide registry that maintains a list of names, minimizing re-use; (3)
>> there is also no registry for the definition of property values ("value0"),
>> again making re-use difficult; and (4) how does one maintain backward
>> compatibility as new hardware comes out? The _DSD method was created
>> @@ -434,7 +447,8 @@ The ACPI specification changes regularly. During the year 2014, for instance,
>> version 5.1 was released and version 6.0 substantially completed, with most of
>> the changes being driven by ARM-specific requirements. Proposed changes are
>> presented and discussed in the ASWG (ACPI Specification Working Group) which
>> -is a part of the UEFI Forum.
>> +is a part of the UEFI Forum. The current version of the ACPI specification
>> +is 6.1 release in January 2016.
>>
>> Participation in this group is open to all UEFI members. Please see
>> http://www.uefi.org/workinggroup for details on group membership.
>>
>
> The rest looks good.
>
> Thanks,
> Harb
>

Thanks for the review, Harb. I haven't received any other comments yet, so
maybe I'll wait until Monday to post a v2 with your suggested changes, just in
case someone else gets a chance to review this.

--
ciao,
al
-----------------------------------
Al Stone
Software Engineer
Red Hat, Inc.
ahs3@redhat.com
-----------------------------------