Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

Pull initial ACPI support for arm64 from Will Deacon:
 "This series introduces preliminary ACPI 5.1 support to the arm64
  kernel using the "hardware reduced" profile.  We don't support any
  peripherals yet, so it's fairly limited in scope:

   - MEMORY init (UEFI)

   - ACPI discovery (RSDP via UEFI)

   - CPU init (FADT)

   - GIC init (MADT)

   - SMP boot (MADT + PSCI)

   - ACPI Kconfig options (dependent on EXPERT)

  ACPI for arm64 has been in development for a while now and hardware
  has been available that can boot with either FDT or ACPI tables.  This
  has been made possible by both changes to the ACPI spec to cater for
  ARM-based machines (known as "hardware-reduced" in ACPI parlance) but
  also a Linaro-driven effort to get this supported on top of the Linux
  kernel.  This pull request is the result of that work.

  These changes allow us to initialise the CPUs, interrupt controller,
  and timers via ACPI tables, with memory information and cmdline coming
  from EFI.  We don't support a hybrid ACPI/FDT scheme.  Of course,
  there is still plenty of work to do (a serial console would be nice!)
  but I expect that to happen on a per-driver basis after this core
  series has been merged.

  Anyway, the diff stat here is fairly horrible, but splitting this up
  and merging it via all the different subsystems would have been
  extremely painful.  Instead, we've got all the relevant Acks in place
  and I've not seen anything other than trivial (Kconfig) conflicts in
  -next (for completeness, I've included my resolution below).  Nearly
  half of the insertions fall under Documentation/.

  So, we'll see how this goes.  Right now, it all depends on EXPERT and
  I fully expect people to use FDT by default for the immediate future"

* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (31 commits)
  ARM64 / ACPI: make acpi_map_gic_cpu_interface() as void function
  ARM64 / ACPI: Ignore the return error value of acpi_map_gic_cpu_interface()
  ARM64 / ACPI: fix usage of acpi_map_gic_cpu_interface
  ARM64: kernel: acpi: honour acpi=force command line parameter
  ARM64: kernel: acpi: refactor ACPI tables init and checks
  ARM64: kernel: psci: let ACPI probe PSCI version
  ARM64: kernel: psci: factor out probe function
  ACPI: move arm64 GSI IRQ model to generic GSI IRQ layer
  ARM64 / ACPI: Don't unflatten device tree if acpi=force is passed
  ARM64 / ACPI: additions of ACPI documentation for arm64
  Documentation: ACPI for ARM64
  ARM64 / ACPI: Enable ARM64 in Kconfig
  XEN / ACPI: Make XEN ACPI depend on X86
  ARM64 / ACPI: Select ACPI_REDUCED_HARDWARE_ONLY if ACPI is enabled on ARM64
  clocksource / arch_timer: Parse GTDT to initialize arch timer
  irqchip: Add GICv2 specific ACPI boot support
  ARM64 / ACPI: Introduce ACPI_IRQ_MODEL_GIC and register device's gsi
  ACPI / processor: Make it possible to get CPU hardware ID via GICC
  ACPI / processor: Introduce phys_cpuid_t for CPU hardware ID
  ARM64 / ACPI: Parse MADT for SMP initialization
  ...

3 files changed, 1100 insertions, 1 deletions

diff --git a/Documentation/arm64/acpi_object_usage.txt b/Documentation/arm64/acpi_object_usage.txt
new file mode 100644
index 000000000000..a6e1a1805e51
--- /dev/null
+++ b/Documentation/arm64/acpi_object_usage.txt
@@ -0,0 +1,593 @@
+ACPI Tables
+-----------
+The expectations of individual ACPI tables are discussed in the list that
+follows.
+
+If a section number is used, it refers to a section number in the ACPI
+specification where the object is defined.  If "Signature Reserved" is used,
+the table signature (the first four bytes of the table) is the only portion
+of the table recognized by the specification, and the actual table is defined
+outside of the UEFI Forum (see Section 5.2.6 of the specification).
+
+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
+
+       -- Optional: BGRT, CPEP, CSRT, DRTM, ECDT, FACS, FPDT, MCHI, MPST,
+          MSCT, RASF, SBST, SLIT, SPMI, SRAT, TCPA, TPM2, UEFI
+
+       -- Not supported: BOOT, DBG2, DBGP, DMAR, ETDT, HPET, IBFT, IVRS,
+          LPIT, MSDM, RSDT, SLIC, WAET, WDAT, WDRT, WPBT
+
+
+Table  Usage for ARMv8 Linux
+-----  ----------------------------------------------------------------
+BERT   Section 18.3 (signature == "BERT")
+       == Boot Error Record Table ==
+       Must be supplied if RAS support is provided by the platform.  It
+       is recommended this table be supplied.
+
+BOOT   Signature Reserved (signature == "BOOT")
+       == simple BOOT flag table ==
+       Microsoft only table, will not be supported.
+
+BGRT   Section 5.2.22 (signature == "BGRT")
+       == Boot Graphics Resource Table ==
+       Optional, not currently supported, with no real use-case for an
+       ARM server.
+
+CPEP   Section 5.2.18 (signature == "CPEP")
+       == Corrected Platform Error Polling table ==
+       Optional, not currently supported, and not recommended until such
+       time as ARM-compatible hardware is available, and the specification
+       suitably modified.
+
+CSRT   Signature Reserved (signature == "CSRT")
+       == Core System Resources Table ==
+       Optional, not currently supported.
+
+DBG2   Signature Reserved (signature == "DBG2")
+       == DeBuG port table 2 ==
+       Microsoft only table, will not be supported.
+
+DBGP   Signature Reserved (signature == "DBGP")
+       == DeBuG Port table ==
+       Microsoft only table, will not be supported.
+
+DSDT   Section 5.2.11.1 (signature == "DSDT")
+       == Differentiated System Description Table ==
+       A DSDT is required; see also SSDT.
+
+       ACPI tables contain only one DSDT but can contain one or more SSDTs,
+       which are optional.  Each SSDT can only add to the ACPI namespace,
+       but cannot modify or replace anything in the DSDT.
+
+DMAR   Signature Reserved (signature == "DMAR")
+       == DMA Remapping table ==
+       x86 only table, will not be supported.
+
+DRTM   Signature Reserved (signature == "DRTM")
+       == Dynamic Root of Trust for Measurement table ==
+       Optional, not currently supported.
+
+ECDT   Section 5.2.16 (signature == "ECDT")
+       == Embedded Controller Description Table ==
+       Optional, not currently supported, but could be used on ARM if and
+       only if one uses the GPE_BIT field to represent an IRQ number, since
+       there are no GPE blocks defined in hardware reduced mode.  This would
+       need to be modified in the ACPI specification.
+
+EINJ   Section 18.6 (signature == "EINJ")
+       == Error Injection table ==
+       This table is very useful for testing platform response to error
+       conditions; it allows one to inject an error into the system as
+       if it had actually occurred.  However, this table should not be
+       shipped with a production system; it should be dynamically loaded
+       and executed with the ACPICA tools only during testing.
+
+ERST   Section 18.5 (signature == "ERST")
+       == Error Record Serialization Table ==
+       On a platform supports RAS, this table must be supplied if it is not
+       UEFI-based; if it is UEFI-based, this table may be supplied. When this
+       table is not present, UEFI run time service will be utilized to save
+       and retrieve hardware error information to and from a persistent store.
+
+ETDT   Signature Reserved (signature == "ETDT")
+       == Event Timer Description Table ==
+       Obsolete table, will not be supported.
+
+FACS   Section 5.2.10 (signature == "FACS")
+       == Firmware ACPI Control Structure ==
+       It is unlikely that this table will be terribly useful.  If it is
+       provided, the Global Lock will NOT be used since it is not part of
+       the hardware reduced profile, and only 64-bit address fields will
+       be considered valid.
+
+FADT   Section 5.2.9 (signature == "FACP")
+       == Fixed ACPI Description Table ==
+       Required for arm64.
+
+       The HW_REDUCED_ACPI flag must be set.  All of the fields that are
+       to be ignored when HW_REDUCED_ACPI is set are expected to be set to
+       zero.
+
+       If an FACS table is provided, the X_FIRMWARE_CTRL field is to be
+       used, not FIRMWARE_CTRL.
+
+       If PSCI is used (as is recommended), make sure that ARM_BOOT_ARCH is
+       filled in properly -- that the PSCI_COMPLIANT flag is set and that
+       PSCI_USE_HVC is set or unset as needed (see table 5-37).
+
+       For the DSDT that is also required, the X_DSDT field is to be used,
+       not the DSDT field.
+
+FPDT   Section 5.2.23 (signature == "FPDT")
+       == Firmware Performance Data Table ==
+       Optional, not currently supported.
+
+GTDT   Section 5.2.24 (signature == "GTDT")
+       == Generic Timer Description Table ==
+       Required for arm64.
+
+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.
+
+       Must be supplied if RAS support is provided by the platform.  It
+       is recommended this table be supplied.
+
+HPET   Signature Reserved (signature == "HPET")
+       == High Precision Event timer Table ==
+       x86 only table, will not be supported.
+
+IBFT   Signature Reserved (signature == "IBFT")
+       == iSCSI Boot Firmware Table ==
+       Microsoft defined table, support TBD.
+
+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.
+
+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).
+
+MCFG   Signature Reserved (signature == "MCFG")
+       == Memory-mapped ConFiGuration space ==
+       If the platform supports PCI/PCIe, an MCFG table is required.
+
+MCHI   Signature Reserved (signature == "MCHI")
+       == Management Controller Host Interface table ==
+       Optional, not currently supported.
+
+MPST   Section 5.2.21 (signature == "MPST")
+       == Memory Power State 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 ==
+       Optional, not currently supported.
+
+RASF   Section 5.2.20 (signature == "RASF")
+       == RAS Feature table ==
+       Optional, not currently supported.
+
+RSDP   Section 5.2.5 (signature == "RSD PTR")
+       == Root System Description PoinTeR ==
+       Required for arm64.
+
+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.
+
+SBST   Section 5.2.14 (signature == "SBST")
+       == Smart Battery Subsystem Table ==
+       Optional, not currently supported.
+
+SLIC   Signature Reserved (signature == "SLIC")
+       == Software LIcensing table ==
+       Microsoft only table, will not be supported.
+
+SLIT   Section 5.2.17 (signature == "SLIT")
+       == System Locality distance Information Table ==
+       Optional in general, but required for NUMA systems.
+
+SPCR   Signature Reserved (signature == "SPCR")
+       == Serial Port Console Redirection table ==
+       Required for arm64.
+
+SPMI   Signature Reserved (signature == "SPMI")
+       == Server Platform Management Interface table ==
+       Optional, not currently supported.
+
+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.
+
+SSDT   Section 5.2.11.2 (signature == "SSDT")
+       == Secondary System Description Table ==
+       These tables are a continuation of the DSDT; these are recommended
+       for use with devices that can be added to a running system, but can
+       also serve the purpose of dividing up device descriptions into more
+       manageable pieces.
+
+       An SSDT can only ADD to the ACPI namespace.  It cannot modify or
+       replace existing device descriptions already in the namespace.
+
+       These tables are optional, however.  ACPI tables should contain only
+       one DSDT but can contain many SSDTs.
+
+TCPA   Signature Reserved (signature == "TCPA")
+       == Trusted Computing Platform Alliance table ==
+       Optional, not currently supported, and may need changes to fully
+       interoperate with arm64.
+
+TPM2   Signature Reserved (signature == "TPM2")
+       == Trusted Platform Module 2 table ==
+       Optional, not currently supported, and may need changes to fully
+       interoperate with arm64.
+
+UEFI   Signature Reserved (signature == "UEFI")
+       == UEFI ACPI data table ==
+       Optional, not currently supported.  No known use case for arm64,
+       at present.
+
+WAET   Signature Reserved (signature == "WAET")
+       == Windows ACPI Emulated devices Table ==
+       Microsoft only table, will not be supported.
+
+WDAT   Signature Reserved (signature == "WDAT")
+       == Watch Dog Action Table ==
+       Microsoft only table, will not be supported.
+
+WDRT   Signature Reserved (signature == "WDRT")
+       == Watch Dog Resource Table ==
+       Microsoft only table, will not be supported.
+
+WPBT   Signature Reserved (signature == "WPBT")
+       == Windows Platform Binary Table ==
+       Microsoft only table, will not be supported.
+
+XSDT   Section 5.2.8 (signature == "XSDT")
+       == eXtended System Description Table ==
+       Required for arm64.
+
+
+ACPI Objects
+------------
+The expectations on individual ACPI objects are discussed in the list that
+follows:
+
+Name   Section         Usage for ARMv8 Linux
+----   ------------    -------------------------------------------------
+_ADR   6.1.1           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 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.
+
+_CDM   6.2.1           Optional, to be used only for processor devices.
+
+_CID   6.1.2           Use as needed.
+
+_CLS   6.1.3           Use as needed.
+
+_CRS   6.2.2           Required on arm64.
+
+_DCK   6.5.2           Optional; not likely to be used on arm64.
+
+_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
+                       careful of its use across OSes.
+
+_DEP   6.5.8           Use as needed.
+
+_DIS   6.2.3           Optional, for power management use.
+
+_DLM   5.7.5           Optional.
+
+_DMA   6.2.4           Optional.
+
+_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
+                       Device Properties UUID.  Only in rare circumstances
+                       should it be necessary to create a new _DSD UUID.
+
+                       In either case, submit the _DSD definition along with
+                       any driver patches for discussion, especially when
+                       device properties are used.  A driver will not be
+                       considered complete without a corresponding _DSD
+                       description.  Once approved by kernel maintainers,
+                       the UUID or device properties must then be registered
+                       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
+                       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.
+
+_EDL   6.3.1           Optional.
+
+_EJD   6.3.2           Optional.
+
+_EJx   6.3.3           Optional.
+
+_FIX   6.2.7           x86 specific, not used on arm64.
+
+\_GL   5.7.1           This object is not to be used in hardware reduced
+                       mode, and therefore should not be used on arm64.
+
+_GLK   6.5.7           This object requires a global lock be defined; there
+                       is no global lock on arm64 since it runs in hardware
+                       reduced mode.  Hence, do not use this object on arm64.
+
+\_GPE  5.3.1           This namespace is for x86 use only.  Do not use it
+                       on arm64.
+
+_GSB   6.2.7           Optional.
+
+_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.
+
+_HPX   6.2.9           Optional, PCI specific.
+
+_HRV   6.1.6           Optional, 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.
+
+_LCK   6.3.4           Optional.
+
+_MAT   6.2.10          Optional; see also the MADT.
+
+_MLS   6.1.7           Optional, but highly recommended for use in
+                       internationalization.
+
+_OFF   7.1.2           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
+                       that can be turned on or off.
+
+\_OS   5.7.3           This method will return "Linux" by default (this is
+                       the value of the macro ACPI_OS_NAME on Linux).  The
+                       command line parameter acpi_os=<string> can be used
+                       to set it to some other value.
+
+_OSC   6.2.11          This method can be a global method in ACPI (i.e.,
+                       \_SB._OSC), or it may be associated with a specific
+                       device (e.g., \_SB.DEV0._OSC), or both.  When used
+                       as a global method, only capabilities published in
+                       the ACPI specification are allowed.  When used as
+                       a device-specific method, the process described for
+                       using _DSD MUST be used to create an _OSC definition;
+                       out-of-process use of _OSC is not allowed.  That is,
+                       submit the device-specific _OSC usage description as
+                       part of the kernel driver submission, get it approved
+                       by the kernel community, then register it with the
+                       UEFI Forum.
+
+\_OSI  5.7.2           Deprecated on ARM64.  Any invocation of this method
+                       will print a warning on the console and return false.
+                       That is, as far as ACPI firmware is concerned, _OSI
+                       cannot be used to determine what sort of system is
+                       being used or what functionality is provided.  The
+                       _OSC method is to be used instead.
+
+_OST   6.3.5           Optional.
+
+_PDC   8.4.1           Deprecated, do not use on arm64.
+
+\_PIC  5.8.1           The method should not be used.  On arm64, the only
+                       interrupt model available is GIC.
+
+_PLD   6.1.8           Optional.
+
+\_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.
+
+_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.
+
+_PRx   7.2.8-11        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.
+
+_PSE   7.2.7           Use as needed; power management specific.
+
+_PSW   7.2.14          Use as needed; power management specific.
+
+_PSx   7.2.2-5         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.
+
+_PXM   6.2.14          Optional.
+
+_REG   6.5.4           Use as needed.
+
+\_REV  5.7.4           Always returns the latest version of ACPI supported.
+
+_RMV   6.3.6           Optional.
+
+\_SB   5.3.1           Required on arm64; all devices must be defined in this
+                       namespace.
+
+_SEG   6.5.6           Use as needed; PCI-specific.
+
+\_SI   5.3.1,          Optional.
+       9.1
+
+_SLI   6.2.15          Optional; recommended when SLIT table is in use.
+
+_STA   6.3.7,          It is recommended to define this method for any device
+       7.1.4           that can be turned on or off.
+
+_SRS   6.2.16          Optional; see also _PRS.
+
+_STR   6.1.10          Recommended for conveying device names to end users;
+                       this is preferred over using _DDN.
+
+_SUB   6.1.9           Use as needed; _HID or _CID are preferred.
+
+_SUN   6.1.11          Optional.
+
+\_Sx   7.3.2           Use as needed; power management specific.
+
+_SxD   7.2.16-19       Use as needed; power management specific.
+
+_SxW   7.2.20-24       Use as needed; power management specific.
+
+_SWS   7.3.3           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.
+
+\_TZ   5.3.1           Optional.
+
+_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.
+
+
+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.
+
+
+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.
+
+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.
+
+
+ACPI System Address Map Interfaces
+----------------------------------
+In Section 15 of the ACPI specification, several methods are mentioned as
+possible mechanisms for conveying memory resource information to the kernel.
+For arm64, we will only support UEFI for booting with ACPI, hence the UEFI
+GetMemoryMap() boot service is the only mechanism that will be used.
+
+
+ACPI Platform Error Interfaces (APEI)
+-------------------------------------
+The APEI tables supported are described above.
+
+APEI requires the equivalent of an SCI and an NMI on ARMv8.  The SCI is used
+to notify the OSPM of errors that have occurred but can be corrected and the
+system can continue correct operation, even if possibly degraded.  The NMI is
+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.
+
+
+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.
+
+These are not supported:
+
+       -- Section 9.2: ambient light sensor devices
+
+       -- Section 9.3: battery devices
+
+       -- Section 9.4: lids (e.g., laptop lids)
+
+       -- Section 9.8.2: IDE controllers
+
+       -- Section 9.9: floppy controllers
+
+       -- Section 9.10: GPE block devices
+
+       -- Section 9.15: PC/AT RTC/CMOS devices
+
+       -- Section 9.16: user presence detection devices
+
+       -- Section 9.17: I/O APIC devices; all GICs must be enumerable via MADT
+
+       -- 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
+
+       -- Section 12: embedded controllers interface
+
+       -- Section 13: SMBus interfaces
+
+       -- Section 17: NUMA support (prototypes have been submitted for
+          review)
diff --git a/Documentation/arm64/arm-acpi.txt b/Documentation/arm64/arm-acpi.txt
new file mode 100644
index 000000000000..570a4f8e1a01
--- /dev/null
+++ b/Documentation/arm64/arm-acpi.txt
@@ -0,0 +1,505 @@
+ACPI on ARMv8 Servers
+---------------------
+ACPI can be used for ARMv8 general purpose servers designed to follow
+the ARM SBSA (Server Base System Architecture) [0] and SBBR (Server
+Base Boot Requirements) [1] specifications.  Please note that the SBBR
+can be retrieved simply by visiting [1], but the SBSA is currently only
+available to those with an ARM login due to ARM IP licensing concerns.
+
+The ARMv8 kernel implements the reduced hardware model of ACPI version
+5.1 or later.  Links to the specification and all external documents
+it refers to are managed by the UEFI Forum.  The specification is
+available at http://www.uefi.org/specifications and documents referenced
+by the specification can be found via http://www.uefi.org/acpi.
+
+If an ARMv8 system does not meet the requirements of the SBSA and SBBR,
+or cannot be described using the mechanisms defined in the required ACPI
+specifications, then ACPI may not be a good fit for the hardware.
+
+While the documents mentioned above set out the requirements for building
+industry-standard ARMv8 servers, they also apply to more than one operating
+system.  The purpose of this document is to describe the interaction between
+ACPI and Linux only, on an ARMv8 system -- that is, what Linux expects of
+ACPI and what ACPI can expect of Linux.
+
+
+Why ACPI on ARM?
+----------------
+Before examining the details of the interface between ACPI and Linux, it is
+useful to understand why ACPI is being used.  Several technologies already
+exist in Linux for describing non-enumerable hardware, after all.  In this
+section we summarize a blog post [2] from Grant Likely that outlines the
+reasoning behind ACPI on ARMv8 servers.  Actually, we snitch a good portion
+of the summary text almost directly, to be honest.
+
+The short form of the rationale for ACPI on ARM is:
+
+-- ACPI’s bytecode (AML) allows the platform to encode hardware behavior,
+   while DT explicitly does not support this.  For hardware vendors, being
+   able to encode behavior is a key tool used in supporting operating
+   system releases on new hardware.
+
+-- ACPI’s OSPM defines a power management model that constrains what the
+   platform is allowed to do into a specific model, while still providing
+   flexibility in hardware design.
+
+-- In the enterprise server environment, ACPI has established bindings (such
+   as for RAS) which are currently used in production systems.  DT does not.
+   Such bindings could be defined in DT at some point, but doing so means ARM
+   and x86 would end up using completely different code paths in both firmware
+   and the kernel.
+
+-- Choosing a single interface to describe the abstraction between a platform
+   and an OS is important.  Hardware vendors would not be required to implement
+   both DT and ACPI if they want to support multiple operating systems.  And,
+   agreeing on a single interface instead of being fragmented into per OS
+   interfaces makes for better interoperability overall.
+
+-- 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
+   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.
+
+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
+kernel, but rather must be split between the platform and the kernel, in
+order to allow for orderly change over time.  ACPI frees the OS from needing
+to understand all the minute details of the hardware so that the OS doesn’t
+need to be ported to each and every device individually.  It allows the
+hardware vendors to take responsibility for power management behaviour without
+depending on an OS release cycle which is not under their control.
+
+ACPI is also important because hardware and OS vendors have already worked
+out the mechanisms for supporting a general purpose computing ecosystem.  The
+infrastructure is in place, the bindings are in place, and the processes are
+in place.  DT does exactly what Linux needs it to when working with vertically
+integrated devices, but there are no good processes for supporting what the
+server vendors need.  Linux could potentially get there with DT, but doing so
+really just duplicates something that already works.  ACPI already does what
+the hardware vendors need, Microsoft won’t collaborate on DT, and hardware
+vendors would still end up providing two completely separate firmware
+interfaces -- one for Linux and one for Windows.
+
+
+Kernel Compatibility
+--------------------
+One of the primary motivations for ACPI is standardization, and using that
+to provide backward compatibility for Linux kernels.  In the server market,
+software and hardware are often used for long periods.  ACPI allows the
+kernel and firmware to agree on a consistent abstraction that can be
+maintained over time, even as hardware or software change.  As long as the
+abstraction is supported, systems can be updated without necessarily having
+to replace the kernel.
+
+When a Linux driver or subsystem is first implemented using ACPI, it by
+definition ends up requiring a specific version of the ACPI specification
+-- it's baseline.  ACPI firmware must continue to work, even though it may
+not be optimal, with the earliest kernel version that first provides support
+for that baseline version of ACPI.  There may be a need for additional drivers,
+but adding new functionality (e.g., CPU power management) should not break
+older kernel versions.  Further, ACPI firmware must also work with the most
+recent version of the kernel.
+
+
+Relationship with Device Tree
+-----------------------------
+ACPI support in drivers and subsystems for ARMv8 should never be mutually
+exclusive with DT support at compile time.
+
+At boot time the kernel will only use one description method depending on
+parameters passed from the bootloader (including kernel bootargs).
+
+Regardless of whether DT or ACPI is used, the kernel must always be capable
+of booting with either scheme (in kernels with both schemes enabled at compile
+time).
+
+
+Booting using ACPI tables
+-------------------------
+The only defined method for passing ACPI tables to the kernel on ARMv8
+is via the UEFI system configuration table.  Just so it is explicit, this
+means that ACPI is only supported on platforms that boot via UEFI.
+
+When an ARMv8 system boots, it can either have DT information, ACPI tables,
+or in some very unusual cases, both.  If no command line parameters are used,
+the kernel will try to use DT for device enumeration; if there is no DT
+present, the kernel will try to use ACPI tables, but only if they are present.
+In neither is available, the kernel will not boot.  If acpi=force is used
+on the command line, the kernel will attempt to use ACPI tables first, but
+fall back to DT if there are no ACPI tables present.  The basic idea is that
+the kernel will not fail to boot unless it absolutely has no other choice.
+
+Processing of ACPI tables may be disabled by passing acpi=off on the kernel
+command line; this is the default behavior.
+
+In order for the kernel to load and use ACPI tables, the UEFI implementation
+MUST set the ACPI_20_TABLE_GUID to point to the RSDP table (the table with
+the ACPI signature "RSD PTR ").  If this pointer is incorrect and acpi=force
+is used, the kernel will disable ACPI and try to use DT to boot instead; the
+kernel has, in effect, determined that ACPI tables are not present at that
+point.
+
+If the pointer to the RSDP table is correct, the table will be mapped into
+the kernel by the ACPI core, using the address provided by UEFI.
+
+The ACPI core will then locate and map in all other ACPI tables provided by
+using the addresses in the RSDP table to find the XSDT (eXtended System
+Description Table).  The XSDT in turn provides the addresses to all other
+ACPI tables provided by the system firmware; the ACPI core will then traverse
+this table and map in the tables listed.
+
+The ACPI core will ignore any provided RSDT (Root System Description Table).
+RSDTs have been deprecated and are ignored on arm64 since they only allow
+for 32-bit addresses.
+
+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
+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
+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):
+
+    -- RSDP (Root System Description Pointer), section 5.2.5
+
+    -- XSDT (eXtended System Description Table), section 5.2.8
+
+    -- FADT (Fixed ACPI Description Table), section 5.2.9
+
+    -- DSDT (Differentiated System Description Table), section
+       5.2.11.1
+
+    -- MADT (Multiple APIC Description Table), section 5.2.12
+
+    -- GTDT (Generic Timer Description Table), section 5.2.24
+
+    -- If PCI is supported, the MCFG (Memory mapped ConFiGuration
+       Table), section 5.2.6, specifically Table 5-31.
+
+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.
+
+
+ACPI Detection
+--------------
+Drivers should determine their probe() type by checking for a null
+value for ACPI_HANDLE, or checking .of_node, or other information in
+the device structure.  This is detailed further in the "Driver
+Recommendations" section.
+
+In non-driver code, if the presence of ACPI needs to be detected at
+runtime, then check the value of acpi_disabled. If CONFIG_ACPI is not
+set, acpi_disabled will always be 1.
+
+
+Device Enumeration
+------------------
+Device descriptions in ACPI should use standard recognized ACPI interfaces.
+These may contain less information than is typically provided via a Device
+Tree description for the same device.  This is also one of the reasons that
+ACPI can be useful -- the driver takes into account that it may have less
+detailed information about the device and uses sensible defaults instead.
+If done properly in the driver, the hardware can change and improve over
+time without the driver having to change at all.
+
+Clocks provide an excellent example.  In DT, clocks need to be specified
+and the drivers need to take them into account.  In ACPI, the assumption
+is that UEFI will leave the device in a reasonable default state, including
+any clock settings.  If for some reason the driver needs to change a clock
+value, this can be done in an ACPI method; all the driver needs to do is
+invoke the method and not concern itself with what the method needs to do
+to change the clock.  Changing the hardware can then take place over time
+by changing what the ACPI method does, and not the driver.
+
+In DT, the parameters needed by the driver to set up clocks as in the example
+above are known as "bindings"; in ACPI, these are known as "Device Properties"
+and provided to a driver via the _DSD object.
+
+ACPI tables are described with a formal language called ASL, the ACPI
+Source Language (section 19 of the specification).  This means that there
+are always multiple ways to describe the same thing -- including device
+properties.  For example, device properties could use an ASL construct
+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)
+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
+to solve precisely these sorts of problems; Linux drivers should ALWAYS
+use the _DSD method for device properties and nothing else.
+
+The _DSM object (ACPI Section 9.14.1) could also be used for conveying
+device properties to a driver.  Linux drivers should only expect it to
+be used if _DSD cannot represent the data required, and there is no way
+to create a new UUID for the _DSD object.  Note that there is even less
+regulation of the use of _DSM than there is of _DSD.  Drivers that depend
+on the contents of _DSM objects will be more difficult to maintain over
+time because of this; as of this writing, the use of _DSM is the cause
+of quite a few firmware problems and is not recommended.
+
+Drivers should look for device properties in the _DSD object ONLY; the _DSD
+object is described in the ACPI specification section 6.2.5, but this only
+describes how to define the structure of an object returned via _DSD, and
+how specific data structures are defined by specific UUIDs.  Linux should
+only use the _DSD Device Properties UUID [5]:
+
+   -- UUID: daffd814-6eba-4d8c-8a91-bc9bbf4aa301
+
+   -- http://www.uefi.org/sites/default/files/resources/_DSD-device-properties-UUID.pdf
+
+The UEFI Forum provides a mechanism for registering device properties [4]
+so that they may be used across all operating systems supporting ACPI.
+Device properties that have not been registered with the UEFI Forum should
+not be used.
+
+Before creating new device properties, check to be sure that they have not
+been defined before and either registered in the Linux kernel documentation
+as DT bindings, or the UEFI Forum as device properties.  While we do not want
+to simply move all DT bindings into ACPI device properties, we can learn from
+what has been previously defined.
+
+If it is necessary to define a new device property, or if it makes sense to
+synthesize the definition of a binding so it can be used in any firmware,
+both DT bindings and ACPI device properties for device drivers have review
+processes.  Use them both.  When the driver itself is submitted for review
+to the Linux mailing lists, the device property definitions needed must be
+submitted at the same time.  A driver that supports ACPI and uses device
+properties will not be considered complete without their definitions.  Once
+the device property has been accepted by the Linux community, it must be
+registered with the UEFI Forum [4], which will review it again for consistency
+within the registry.  This may require iteration.  The UEFI Forum, though,
+will always be the canonical site for device property definitions.
+
+It may make sense to provide notice to the UEFI Forum that there is the
+intent to register a previously unused device property name as a means of
+reserving the name for later use.  Other operating system vendors will
+also be submitting registration requests and this may help smooth the
+process.
+
+Once registration and review have been completed, the kernel provides an
+interface for looking up device properties in a manner independent of
+whether DT or ACPI is being used.  This API should be used [6]; it can
+eliminate some duplication of code paths in driver probing functions and
+discourage divergence between DT bindings and ACPI device properties.
+
+
+Programmable Power Control Resources
+------------------------------------
+Programmable power control resources include such resources as voltage/current
+providers (regulators) and clock sources.
+
+With ACPI, the kernel clock and regulator framework is not expected to be used
+at all.
+
+The kernel assumes that power control of these resources is represented with
+Power Resource Objects (ACPI section 7.1).  The ACPI core will then handle
+correctly enabling and disabling resources as they are needed.  In order to
+get that to work, ACPI assumes each device has defined D-states and that these
+can be controlled through the optional ACPI methods _PS0, _PS1, _PS2, and _PS3;
+in ACPI, _PS0 is the method to invoke to turn a device full on, and _PS3 is for
+turning a device full off.
+
+There are two options for using those Power Resources.  They can:
+
+   -- be managed in a _PSx method which gets called on entry to power
+      state Dx.
+
+   -- be declared separately as power resources with their own _ON and _OFF
+      methods.  They are then tied back to D-states for a particular device
+      via _PRx which specifies which power resources a device needs to be on
+      while in Dx.  Kernel then tracks number of devices using a power resource
+      and calls _ON/_OFF as needed.
+
+The kernel ACPI code will also assume that the _PSx methods follow the normal
+ACPI rules for such methods:
+
+   -- If either _PS0 or _PS3 is implemented, then the other method must also
+      be implemented.
+
+   -- If a device requires usage or setup of a power resource when on, the ASL
+      should organize that it is allocated/enabled using the _PS0 method.
+
+   -- Resources allocated or enabled in the _PS0 method should be disabled
+      or de-allocated in the _PS3 method.
+
+   -- Firmware will leave the resources in a reasonable state before handing
+      over control to the kernel.
+
+Such code in _PSx methods will of course be very platform specific.  But,
+this allows the driver to abstract out the interface for operating the device
+and avoid having to read special non-standard values from ACPI tables. Further,
+abstracting the use of these resources allows the hardware to change over time
+without requiring updates to the driver.
+
+
+Clocks
+------
+ACPI makes the assumption that clocks are initialized by the firmware --
+UEFI, in this case -- to some working value before control is handed over
+to the kernel.  This has implications for devices such as UARTs, or SoC-driven
+LCD displays, for example.
+
+When the kernel boots, the clocks are assumed to be set to reasonable
+working values.  If for some reason the frequency needs to change -- e.g.,
+throttling for power management -- the device driver should expect that
+process to be abstracted out into some ACPI method that can be invoked
+(please see the ACPI specification for further recommendations on standard
+methods to be expected).  The only exceptions to this are CPU clocks where
+CPPC provides a much richer interface than ACPI methods.  If the clocks
+are not set, there is no direct way for Linux to control them.
+
+If an SoC vendor wants to provide fine-grained control of the system clocks,
+they could do so by providing ACPI methods that could be invoked by Linux
+drivers.  However, this is NOT recommended and Linux drivers should NOT use
+such methods, even if they are provided.  Such methods are not currently
+standardized in the ACPI specification, and using them could tie a kernel
+to a very specific SoC, or tie an SoC to a very specific version of the
+kernel, both of which we are trying to avoid.
+
+
+Driver Recommendations
+----------------------
+DO NOT remove any DT handling when adding ACPI support for a driver.  The
+same device may be used on many different systems.
+
+DO try to structure the driver so that it is data-driven.  That is, set up
+a struct containing internal per-device state based on defaults and whatever
+else must be discovered by the driver probe function.  Then, have the rest
+of the driver operate off of the contents of that struct.  Doing so should
+allow most divergence between ACPI and DT functionality to be kept local to
+the probe function instead of being scattered throughout the driver.  For
+example:
+
+static int device_probe_dt(struct platform_device *pdev)
+{
+       /* DT specific functionality */
+       ...
+}
+
+static int device_probe_acpi(struct platform_device *pdev)
+{
+       /* ACPI specific functionality */
+       ...
+}
+
+static int device_probe(struct platform_device *pdev)
+{
+       ...
+       struct device_node node = pdev->dev.of_node;
+       ...
+
+       if (node)
+               ret = device_probe_dt(pdev);
+       else if (ACPI_HANDLE(&pdev->dev))
+               ret = device_probe_acpi(pdev);
+       else
+               /* other initialization */
+               ...
+       /* Continue with any generic probe operations */
+       ...
+}
+
+DO keep the MODULE_DEVICE_TABLE entries together in the driver to make it
+clear the different names the driver is probed for, both from DT and from
+ACPI:
+
+static struct of_device_id virtio_mmio_match[] = {
+        { .compatible = "virtio,mmio", },
+        { }
+};
+MODULE_DEVICE_TABLE(of, virtio_mmio_match);
+
+static const struct acpi_device_id virtio_mmio_acpi_match[] = {
+        { "LNRO0005", },
+        { }
+};
+MODULE_DEVICE_TABLE(acpi, virtio_mmio_acpi_match);
+
+
+ASWG
+----
+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.
+
+Participation in this group is open to all UEFI members.  Please see
+http://www.uefi.org/workinggroup for details on group membership.
+
+It is the intent of the ARMv8 ACPI kernel code to follow the ACPI specification
+as closely as possible, and to only implement functionality that complies with
+the released standards from UEFI ASWG.  As a practical matter, there will be
+vendors that provide bad ACPI tables or violate the standards in some way.
+If this is because of errors, quirks and fixups may be necessary, but will
+be avoided if possible.  If there are features missing from ACPI that preclude
+it from being used on a platform, ECRs (Engineering Change Requests) should be
+submitted to ASWG and go through the normal approval process; for those that
+are not UEFI members, many other members of the Linux community are and would
+likely be willing to assist in submitting ECRs.
+
+
+Linux Code
+----------
+Individual items specific to Linux on ARM, contained in the the Linux
+source code, are in the list that follows:
+
+ACPI_OS_NAME           This macro defines the string to be returned when
+                       an ACPI method invokes the _OS method.  On ARM64
+                       systems, this macro will be "Linux" by default.
+                       The command line parameter acpi_os=<string>
+                       can be used to set it to some other value.  The
+                       default value for other architectures is "Microsoft
+                       Windows NT", for example.
+
+ACPI Objects
+------------
+Detailed expectations for ACPI tables and object are listed in the file
+Documentation/arm64/acpi_object_usage.txt.
+
+
+References
+----------
+[0] http://silver.arm.com -- document ARM-DEN-0029, or newer
+    "Server Base System Architecture", version 2.3, dated 27 Mar 2014
+
+[1] http://infocenter.arm.com/help/topic/com.arm.doc.den0044a/Server_Base_Boot_Requirements.pdf
+    Document ARM-DEN-0044A, or newer: "Server Base Boot Requirements, System
+    Software on ARM Platforms", dated 16 Aug 2014
+
+[2] http://www.secretlab.ca/archives/151, 10 Jan 2015, Copyright (c) 2015,
+    Linaro Ltd., written by Grant Likely.  A copy of the verbatim text (apart
+    from formatting) is also in Documentation/arm64/why_use_acpi.txt.
+
+[3] AMD ACPI for Seattle platform documentation:
+    http://amd-dev.wpengine.netdna-cdn.com/wordpress/media/2012/10/Seattle_ACPI_Guide.pdf
+
+[4] http://www.uefi.org/acpi -- please see the link for the "ACPI _DSD Device
+    Property Registry Instructions"
+
+[5] http://www.uefi.org/acpi -- please see the link for the "_DSD (Device
+    Specific Data) Implementation Guide"
+
+[6] Kernel code for the unified device property interface can be found in
+    include/linux/property.h and drivers/base/property.c.
+
+
+Authors
+-------
+Al Stone <al.stone@linaro.org>
+Graeme Gregory <graeme.gregory@linaro.org>
+Hanjun Guo <hanjun.guo@linaro.org>
+
+Grant Likely <grant.likely@linaro.org>, for the "Why ACPI on ARM?" section
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 84960c66c77b..f6befa9855c1 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -165,7 +165,7 @@ multipliers 'Kilo', 'Mega', and 'Giga', equalling 2^10, 2^20, and 2^30
 bytes respectively. Such letter suffixes can also be entirely omitted.
 
 
-	acpi=		[HW,ACPI,X86]
+	acpi=		[HW,ACPI,X86,ARM64]
 			Advanced Configuration and Power Interface
 			Format: { force | off | strict | noirq | rsdt }
 			force -- enable ACPI if default was off
@@ -175,6 +175,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 				strictly ACPI specification compliant.
 			rsdt -- prefer RSDT over (default) XSDT
 			copy_dsdt -- copy DSDT to memory
+			For ARM64, ONLY "acpi=off" or "acpi=force" are available
 
 			See also Documentation/power/runtime_pm.txt, pci=noacpi