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

From: [email-masked] (Al Stone)
Date: Fri, 26 Feb 2016 14:28:41 -0700

On 02/20/2016 01:47 PM, Abdulhamid, Harb wrote:
> On 2/19/2016 6:54 PM, al.stone at linaro.org wrote:
>> From: Al Stone <[email-masked]>	
>>
>> 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 <[email-masked]>
>> ---
>>  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 at redhat.com
-----------------------------------