linux-sg2042/drivers/acpi/Kconfig

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License cleanup: add SPDX GPL-2.0 license identifier to files with no license Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-01 22:07:57 +08:00
# SPDX-License-Identifier: GPL-2.0
#
# ACPI Configuration
#
config ARCH_SUPPORTS_ACPI
bool
menuconfig ACPI
bool "ACPI (Advanced Configuration and Power Interface) Support"
depends on ARCH_SUPPORTS_ACPI
depends on PCI
select PNP
default y if X86
help
Advanced Configuration and Power Interface (ACPI) support for
Linux requires an ACPI-compliant platform (hardware/firmware),
and assumes the presence of OS-directed configuration and power
management (OSPM) software. This option will enlarge your
kernel by about 70K.
Linux ACPI provides a robust functional replacement for several
legacy configuration and power management interfaces, including
the Plug-and-Play BIOS specification (PnP BIOS), the
MultiProcessor Specification (MPS), and the Advanced Power
Management (APM) specification. If both ACPI and APM support
are configured, ACPI is used.
The project home page for the Linux ACPI subsystem is here:
<https://01.org/linux-acpi>
Linux support for ACPI is based on Intel Corporation's ACPI
Component Architecture (ACPI CA). For more information on the
ACPI CA, see:
<http://acpica.org/>
ACPI is an open industry specification originally co-developed by
Hewlett-Packard, Intel, Microsoft, Phoenix, and Toshiba. Currently,
it is developed by the ACPI Specification Working Group (ASWG) under
the UEFI Forum and any UEFI member can join the ASWG and contribute
to the ACPI specification.
The specification is available at:
<http://www.acpi.info>
<http://www.uefi.org/acpi/specs>
if ACPI
config ACPI_LEGACY_TABLES_LOOKUP
bool
config ARCH_MIGHT_HAVE_ACPI_PDC
bool
ACPI: move arm64 GSI IRQ model to generic GSI IRQ layer The code deployed to implement GSI linux IRQ numbers mapping on arm64 turns out to be generic enough so that it can be moved to ACPI core code along with its respective config option ACPI_GENERIC_GSI selectable on architectures that can reuse the same code. Current ACPI IRQ mapping code is not integrated in the kernel IRQ domain infrastructure, in particular there is no way to look-up the IRQ domain associated with a particular interrupt controller, so this first version of GSI generic code carries out the GSI<->IRQ mapping relying on the IRQ default domain which is supposed to be always set on a specific architecture in case the domain structure passed to irq_create/find_mapping() functions is missing. This patch moves the arm64 acpi functions that implement the gsi mappings: acpi_gsi_to_irq() acpi_register_gsi() acpi_unregister_gsi() to ACPI core code. Since the generic GSI<->domain mapping is based on IRQ domains, it can be extended as soon as a way to map an interrupt controller to an IRQ domain is implemented for ACPI in the IRQ domain layer. x86 and ia64 code for GSI mappings cannot rely on the generic GSI layer at present for legacy reasons, so they do not select the ACPI_GENERIC_GSI config options and keep relying on their arch specific GSI mapping layer. Cc: Jiang Liu <jiang.liu@linux.intel.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Rafael J. Wysocki <rjw@rjwysocki.net> Acked-by: Hanjun Guo <hanjun.guo@linaro.org> Acked-by: Will Deacon <will.deacon@arm.com> Acked-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2015-03-25 01:58:51 +08:00
config ACPI_GENERIC_GSI
bool
config ACPI_SYSTEM_POWER_STATES_SUPPORT
bool
config ACPI_CCA_REQUIRED
bool
ACPI: Enable build of AML interpreter debugger This patch enables ACPICA debugger files using a configurable CONFIG_ACPI_DEBUGGER configuration item. Those debugger related code that was originally masked as ACPI_FUTURE_USAGE now gets unmasked. Necessary OSL stubs are also added in this patch: 1. acpi_os_readable(): This should be arch specific in Linux, while this patch doesn't introduce real implementation and a complex mechanism to allow architecture specific acpi_os_readable() to be implemented to validate the address. It may be done by future commits. 2. acpi_os_get_line(): This is used to obtain debugger command input. This patch only introduces a simple KDB concept example in it and the example should be co-working with the code implemented in acpi_os_printf(). Since this KDB example won't be compiled unless ENABLE_DEBUGGER is defined and it seems Linux has already stopped to use ENABLE_DEBUGGER, thus do not expect it can work properly. This patch also cleans up all other ACPI_FUTURE_USAGE surroundings accordingly. 1. Since linkage error can be automatically detected, declaration in the headers needn't be surrounded by ACPI_FUTURE_USAGE. So only the following separate exported fuction bodies are masked by this macro (other exported fucntions may have already been masked at entire module level via drivers/acpi/acpica/Makefile): acpi_install_exception_handler() acpi_subsystem_status() acpi_get_system_info() acpi_get_statistics() acpi_install_initialization_handler() 2. Since strip can automatically zap the no-user functions, functions that are not marked with ACPI_EXPORT_SYMBOL() needn't get surrounded by ACPI_FUTURE_USAGE. So the following function which is not used by Linux kernel now won't get surrounded by this macro: acpi_ps_get_name() Signed-off-by: Lv Zheng <lv.zheng@intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-10-19 10:25:56 +08:00
config ACPI_DEBUGGER
bool "AML debugger interface"
ACPI: Enable build of AML interpreter debugger This patch enables ACPICA debugger files using a configurable CONFIG_ACPI_DEBUGGER configuration item. Those debugger related code that was originally masked as ACPI_FUTURE_USAGE now gets unmasked. Necessary OSL stubs are also added in this patch: 1. acpi_os_readable(): This should be arch specific in Linux, while this patch doesn't introduce real implementation and a complex mechanism to allow architecture specific acpi_os_readable() to be implemented to validate the address. It may be done by future commits. 2. acpi_os_get_line(): This is used to obtain debugger command input. This patch only introduces a simple KDB concept example in it and the example should be co-working with the code implemented in acpi_os_printf(). Since this KDB example won't be compiled unless ENABLE_DEBUGGER is defined and it seems Linux has already stopped to use ENABLE_DEBUGGER, thus do not expect it can work properly. This patch also cleans up all other ACPI_FUTURE_USAGE surroundings accordingly. 1. Since linkage error can be automatically detected, declaration in the headers needn't be surrounded by ACPI_FUTURE_USAGE. So only the following separate exported fuction bodies are masked by this macro (other exported fucntions may have already been masked at entire module level via drivers/acpi/acpica/Makefile): acpi_install_exception_handler() acpi_subsystem_status() acpi_get_system_info() acpi_get_statistics() acpi_install_initialization_handler() 2. Since strip can automatically zap the no-user functions, functions that are not marked with ACPI_EXPORT_SYMBOL() needn't get surrounded by ACPI_FUTURE_USAGE. So the following function which is not used by Linux kernel now won't get surrounded by this macro: acpi_ps_get_name() Signed-off-by: Lv Zheng <lv.zheng@intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-10-19 10:25:56 +08:00
select ACPI_DEBUG
help
Enable in-kernel debugging of AML facilities: statistics,
internal object dump, single step control method execution.
ACPI: Enable build of AML interpreter debugger This patch enables ACPICA debugger files using a configurable CONFIG_ACPI_DEBUGGER configuration item. Those debugger related code that was originally masked as ACPI_FUTURE_USAGE now gets unmasked. Necessary OSL stubs are also added in this patch: 1. acpi_os_readable(): This should be arch specific in Linux, while this patch doesn't introduce real implementation and a complex mechanism to allow architecture specific acpi_os_readable() to be implemented to validate the address. It may be done by future commits. 2. acpi_os_get_line(): This is used to obtain debugger command input. This patch only introduces a simple KDB concept example in it and the example should be co-working with the code implemented in acpi_os_printf(). Since this KDB example won't be compiled unless ENABLE_DEBUGGER is defined and it seems Linux has already stopped to use ENABLE_DEBUGGER, thus do not expect it can work properly. This patch also cleans up all other ACPI_FUTURE_USAGE surroundings accordingly. 1. Since linkage error can be automatically detected, declaration in the headers needn't be surrounded by ACPI_FUTURE_USAGE. So only the following separate exported fuction bodies are masked by this macro (other exported fucntions may have already been masked at entire module level via drivers/acpi/acpica/Makefile): acpi_install_exception_handler() acpi_subsystem_status() acpi_get_system_info() acpi_get_statistics() acpi_install_initialization_handler() 2. Since strip can automatically zap the no-user functions, functions that are not marked with ACPI_EXPORT_SYMBOL() needn't get surrounded by ACPI_FUTURE_USAGE. So the following function which is not used by Linux kernel now won't get surrounded by this macro: acpi_ps_get_name() Signed-off-by: Lv Zheng <lv.zheng@intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-10-19 10:25:56 +08:00
This is still under development, currently enabling this only
results in the compilation of the ACPICA debugger files.
if ACPI_DEBUGGER
config ACPI_DEBUGGER_USER
tristate "Userspace debugger accessiblity"
depends on DEBUG_FS
help
Export /sys/kernel/debug/acpi/acpidbg for userspace utilities
to access the debugger functionalities.
endif
config ACPI_SPCR_TABLE
bool "ACPI Serial Port Console Redirection Support"
default y if X86
help
Enable support for Serial Port Console Redirection (SPCR) Table.
This table provides information about the configuration of the
earlycon console.
ACPI / LPIT: Add Low Power Idle Table (LPIT) support Add functionality to read LPIT table, which provides: - Sysfs interface to read residency counters via /sys/devices/system/cpu/cpuidle/low_power_idle_cpu_residency_us /sys/devices/system/cpu/cpuidle/low_power_idle_system_residency_us Here the count "low_power_idle_cpu_residency_us" shows the time spent by CPU package in low power state. This is read via MSR interface, which points to MSR for PKG C10. Here the count "low_power_idle_system_residency_us" show the count the system was in low power state. This is read via MMIO interface. This is mapped to SLP_S0 residency on modern Intel systems. This residency is achieved only when CPU is in PKG C10 and all functional blocks are in low power state. It is possible that none of the above counters present or anyone of the counter present or all counters present. For example: On my Kabylake system both of the above counters present. After suspend to idle these counts updated and prints: 6916179 6998564 This counter can be read by tools like turbostat to display. Or it can be used to debug, if modern systems are reaching desired low power state. - Provides an interface to read residency counter memory address This address can be used to get the base address of PMC memory mapped IO. This is utilized by intel_pmc_core driver to print more debug information. In addition, to avoid code duplication to read iomem, removed the read of iomem from acpi_os_read_memory() in osl.c and made a common function acpi_os_read_iomem(). This new function is used for reading iomem in in both osl.c and acpi_lpit.c. Link: http://www.uefi.org/sites/default/files/resources/Intel_ACPI_Low_Power_S0_Idle.pdf Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-10-06 07:24:03 +08:00
config ACPI_LPIT
bool
depends on X86_64
default y
config ACPI_SLEEP
bool
depends on SUSPEND || HIBERNATION
depends on ACPI_SYSTEM_POWER_STATES_SUPPORT
default y
config ACPI_PROCFS_POWER
bool "Deprecated power /proc/acpi directories"
depends on X86 && PROC_FS
help
For backwards compatibility, this option allows
deprecated power /proc/acpi/ directories to exist, even when
they have been replaced by functions in /sys.
The deprecated directories (and their replacements) include:
/proc/acpi/battery/* (/sys/class/power_supply/*) and
/proc/acpi/ac_adapter/* (sys/class/power_supply/*).
This option has no effect on /proc/acpi/ directories
and functions which do not yet exist in /sys.
This option, together with the proc directories, will be
deleted in the future.
Say N to delete power /proc/acpi/ directories that have moved to /sys.
config ACPI_REV_OVERRIDE_POSSIBLE
bool "Allow supported ACPI revision to be overridden"
depends on X86
default y
help
The platform firmware on some systems expects Linux to return "5" as
the supported ACPI revision which makes it expose system configuration
information in a special way.
For example, based on what ACPI exports as the supported revision,
Dell XPS 13 (2015) configures its audio device to either work in HDA
mode or in I2S mode, where the former is supposed to be used on Linux
until the latter is fully supported (in the kernel as well as in user
space).
This option enables a DMI-based quirk for the above Dell machine (so
that HDA audio is exposed by the platform firmware to the kernel) and
makes it possible to force the kernel to return "5" as the supported
ACPI revision via the "acpi_rev_override" command line switch.
config ACPI_EC_DEBUGFS
tristate "EC read/write access through /sys/kernel/debug/ec"
help
Say N to disable Embedded Controller /sys/kernel/debug interface
Be aware that using this interface can confuse your Embedded
Controller in a way that a normal reboot is not enough. You then
have to power off your system, and remove the laptop battery for
some seconds.
An Embedded Controller typically is available on laptops and reads
sensor values like battery state and temperature.
The kernel accesses the EC through ACPI parsed code provided by BIOS
tables. This option allows to access the EC directly without ACPI
code being involved.
Thus this option is a debug option that helps to write ACPI drivers
and can be used to identify ACPI code or EC firmware bugs.
config ACPI_AC
tristate "AC Adapter"
depends on X86
select POWER_SUPPLY
default y
help
This driver supports the AC Adapter object, which indicates
whether a system is on AC or not. If you have a system that can
switch between A/C and battery, say Y.
To compile this driver as a module, choose M here:
the module will be called ac.
config ACPI_BATTERY
tristate "Battery"
depends on X86
select POWER_SUPPLY
default y
help
This driver adds support for battery information through
/proc/acpi/battery. If you have a mobile system with a battery,
say Y.
To compile this driver as a module, choose M here:
the module will be called battery.
config ACPI_BUTTON
tristate "Button"
depends on INPUT
default y
help
This driver handles events on the power, sleep, and lid buttons.
A daemon reads events from input devices or via netlink and
performs user-defined actions such as shutting down the system.
This is necessary for software-controlled poweroff.
To compile this driver as a module, choose M here:
the module will be called button.
config ACPI_VIDEO
tristate "Video"
depends on X86 && BACKLIGHT_CLASS_DEVICE
depends on INPUT
select THERMAL
help
This driver implements the ACPI Extensions For Display Adapters
for integrated graphics devices on motherboard, as specified in
ACPI 2.0 Specification, Appendix B. This supports basic operations
such as defining the video POST device, retrieving EDID information,
and setting up a video output.
To compile this driver as a module, choose M here:
the module will be called video.
config ACPI_FAN
tristate "Fan"
depends on THERMAL
default y
help
This driver supports ACPI fan devices, allowing user-mode
applications to perform basic fan control (on, off, status).
To compile this driver as a module, choose M here:
the module will be called fan.
config ACPI_TAD
tristate "ACPI Time and Alarm (TAD) Device Support"
depends on SYSFS && PM_SLEEP
help
The ACPI Time and Alarm (TAD) device is an alternative to the Real
Time Clock (RTC). Its wake timers allow the system to transition from
the S3 (or optionally S4/S5) state to S0 state after a time period
elapses. In comparison with the RTC Alarm, the TAD provides a larger
scale of flexibility in the wake timers. The time capabilities of the
TAD maintain the time of day information across platform power
transitions, and keep track of time even when the platform is turned
off.
config ACPI_DOCK
bool "Dock"
help
This driver supports ACPI-controlled docking stations and removable
drive bays such as the IBM Ultrabay and the Dell Module Bay.
config ACPI_CPU_FREQ_PSS
bool
select THERMAL
config ACPI_PROCESSOR_CSTATE
def_bool y
depends on IA64 || X86
config ACPI_PROCESSOR_IDLE
bool
select CPU_IDLE
config ACPI_MCFG
bool
config ACPI_CPPC_LIB
bool
depends on ACPI_PROCESSOR
select MAILBOX
select PCC
help
If this option is enabled, this file implements common functionality
to parse CPPC tables as described in the ACPI 5.1+ spec. The
routines implemented are meant to be used by other
drivers to control CPU performance using CPPC semantics.
If your platform does not support CPPC in firmware,
leave this option disabled.
config ACPI_PROCESSOR
tristate "Processor"
depends on X86 || IA64 || ARM64
select ACPI_PROCESSOR_IDLE
select ACPI_CPU_FREQ_PSS if X86 || IA64
default y
help
This driver adds support for the ACPI Processor package. It is required
by several flavors of cpufreq performance-state, thermal, throttling and
idle drivers.
To compile this driver as a module, choose M here:
the module will be called processor.
config ACPI_IPMI
tristate "IPMI"
depends on IPMI_HANDLER
help
This driver enables the ACPI to access the BMC controller. And it
uses the IPMI request/response message to communicate with BMC
controller, which can be found on on the server.
To compile this driver as a module, choose M here:
the module will be called as acpi_ipmi.
config ACPI_HOTPLUG_CPU
bool
depends on ACPI_PROCESSOR && HOTPLUG_CPU
select ACPI_CONTAINER
default y
ACPI: create Processor Aggregator Device driver ACPI 4.0 created the logical "processor aggregator device" as a mechinism for platforms to ask the OS to force otherwise busy processors to enter (power saving) idle. The intent is to lower power consumption to ride-out transient electrical and thermal emergencies, rather than powering off the server. On platforms that can save more power/performance via P-states, the platform will first exhaust P-states before forcing idle. However, the relative benefit of P-states vs. idle states is platform dependent, and thus this driver need not know or care about it. This driver does not use the kernel's CPU hot-plug mechanism because after the transient emergency is over, the system must be returned to its normal state, and hotplug would permanently break both cpusets and binding. So to force idle, the driver creates a power saving thread. The scheduler will migrate the thread to the preferred CPU. The thread has max priority and has SCHED_RR policy, so it can occupy one CPU. To save power, the thread will invoke the deep C-state entry instructions. To avoid starvation, the thread will sleep 5% of the time time for every second (current RT scheduler has threshold to avoid starvation, but if other CPUs are idle, the CPU can borrow CPU timer from other, which makes the mechanism not work here) Vaidyanathan Srinivasan has proposed scheduler enhancements to allow injecting idle time into the system. This driver doesn't depend on those enhancements, but could cut over to them when they are available. Peter Z. does not favor upstreaming this driver until the those scheduler enhancements are in place. However, we favor upstreaming this driver now because it is useful now, and can be enhanced over time. Signed-off-by: Shaohua Li <shaohua.li@intel.com> NACKed-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com> Signed-off-by: Len Brown <len.brown@intel.com>
2009-07-28 06:11:02 +08:00
config ACPI_PROCESSOR_AGGREGATOR
tristate "Processor Aggregator"
depends on ACPI_PROCESSOR
depends on X86
ACPI: create Processor Aggregator Device driver ACPI 4.0 created the logical "processor aggregator device" as a mechinism for platforms to ask the OS to force otherwise busy processors to enter (power saving) idle. The intent is to lower power consumption to ride-out transient electrical and thermal emergencies, rather than powering off the server. On platforms that can save more power/performance via P-states, the platform will first exhaust P-states before forcing idle. However, the relative benefit of P-states vs. idle states is platform dependent, and thus this driver need not know or care about it. This driver does not use the kernel's CPU hot-plug mechanism because after the transient emergency is over, the system must be returned to its normal state, and hotplug would permanently break both cpusets and binding. So to force idle, the driver creates a power saving thread. The scheduler will migrate the thread to the preferred CPU. The thread has max priority and has SCHED_RR policy, so it can occupy one CPU. To save power, the thread will invoke the deep C-state entry instructions. To avoid starvation, the thread will sleep 5% of the time time for every second (current RT scheduler has threshold to avoid starvation, but if other CPUs are idle, the CPU can borrow CPU timer from other, which makes the mechanism not work here) Vaidyanathan Srinivasan has proposed scheduler enhancements to allow injecting idle time into the system. This driver doesn't depend on those enhancements, but could cut over to them when they are available. Peter Z. does not favor upstreaming this driver until the those scheduler enhancements are in place. However, we favor upstreaming this driver now because it is useful now, and can be enhanced over time. Signed-off-by: Shaohua Li <shaohua.li@intel.com> NACKed-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com> Signed-off-by: Len Brown <len.brown@intel.com>
2009-07-28 06:11:02 +08:00
help
ACPI 4.0 defines processor Aggregator, which enables OS to perform
specific processor configuration and control that applies to all
ACPI: create Processor Aggregator Device driver ACPI 4.0 created the logical "processor aggregator device" as a mechinism for platforms to ask the OS to force otherwise busy processors to enter (power saving) idle. The intent is to lower power consumption to ride-out transient electrical and thermal emergencies, rather than powering off the server. On platforms that can save more power/performance via P-states, the platform will first exhaust P-states before forcing idle. However, the relative benefit of P-states vs. idle states is platform dependent, and thus this driver need not know or care about it. This driver does not use the kernel's CPU hot-plug mechanism because after the transient emergency is over, the system must be returned to its normal state, and hotplug would permanently break both cpusets and binding. So to force idle, the driver creates a power saving thread. The scheduler will migrate the thread to the preferred CPU. The thread has max priority and has SCHED_RR policy, so it can occupy one CPU. To save power, the thread will invoke the deep C-state entry instructions. To avoid starvation, the thread will sleep 5% of the time time for every second (current RT scheduler has threshold to avoid starvation, but if other CPUs are idle, the CPU can borrow CPU timer from other, which makes the mechanism not work here) Vaidyanathan Srinivasan has proposed scheduler enhancements to allow injecting idle time into the system. This driver doesn't depend on those enhancements, but could cut over to them when they are available. Peter Z. does not favor upstreaming this driver until the those scheduler enhancements are in place. However, we favor upstreaming this driver now because it is useful now, and can be enhanced over time. Signed-off-by: Shaohua Li <shaohua.li@intel.com> NACKed-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com> Signed-off-by: Len Brown <len.brown@intel.com>
2009-07-28 06:11:02 +08:00
processors in the platform. Currently only logical processor idling
is defined, which is to reduce power consumption. This driver
supports the new device.
ACPI: create Processor Aggregator Device driver ACPI 4.0 created the logical "processor aggregator device" as a mechinism for platforms to ask the OS to force otherwise busy processors to enter (power saving) idle. The intent is to lower power consumption to ride-out transient electrical and thermal emergencies, rather than powering off the server. On platforms that can save more power/performance via P-states, the platform will first exhaust P-states before forcing idle. However, the relative benefit of P-states vs. idle states is platform dependent, and thus this driver need not know or care about it. This driver does not use the kernel's CPU hot-plug mechanism because after the transient emergency is over, the system must be returned to its normal state, and hotplug would permanently break both cpusets and binding. So to force idle, the driver creates a power saving thread. The scheduler will migrate the thread to the preferred CPU. The thread has max priority and has SCHED_RR policy, so it can occupy one CPU. To save power, the thread will invoke the deep C-state entry instructions. To avoid starvation, the thread will sleep 5% of the time time for every second (current RT scheduler has threshold to avoid starvation, but if other CPUs are idle, the CPU can borrow CPU timer from other, which makes the mechanism not work here) Vaidyanathan Srinivasan has proposed scheduler enhancements to allow injecting idle time into the system. This driver doesn't depend on those enhancements, but could cut over to them when they are available. Peter Z. does not favor upstreaming this driver until the those scheduler enhancements are in place. However, we favor upstreaming this driver now because it is useful now, and can be enhanced over time. Signed-off-by: Shaohua Li <shaohua.li@intel.com> NACKed-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com> Signed-off-by: Len Brown <len.brown@intel.com>
2009-07-28 06:11:02 +08:00
config ACPI_THERMAL
tristate "Thermal Zone"
depends on ACPI_PROCESSOR
select THERMAL
default y
help
This driver supports ACPI thermal zones. Most mobile and
some desktop systems support ACPI thermal zones. It is HIGHLY
recommended that this option be enabled, as your processor(s)
may be damaged without it.
To compile this driver as a module, choose M here:
the module will be called thermal.
config ACPI_NUMA
bool "NUMA support"
depends on NUMA
depends on (X86 || IA64 || ARM64)
default y if IA64_GENERIC || IA64_SGI_SN2 || ARM64
config ACPI_CUSTOM_DSDT_FILE
string "Custom DSDT Table file to include"
default ""
depends on !STANDALONE
help
This option supports a custom DSDT by linking it into the kernel.
See Documentation/acpi/dsdt-override.txt
Enter the full path name to the file which includes the AmlCode
declaration.
If unsure, don't enter a file name.
config ACPI_CUSTOM_DSDT
bool
default ACPI_CUSTOM_DSDT_FILE != ""
config ARCH_HAS_ACPI_TABLE_UPGRADE
def_bool n
ACPI / tables: Convert initrd table override to table upgrade mechanism This patch converts the initrd table override mechanism to the table upgrade mechanism by restricting its usage to the tables released with compatibility and more recent revision. This use case has been encouraged by the ACPI specification: 1. OEMID: An OEM-supplied string that identifies the OEM. 2. OEM Table ID: An OEM-supplied string that the OEM uses to identify the particular data table. This field is particularly useful when defining a definition block to distinguish definition block functions. OEM assigns each dissimilar table a new OEM Table Id. 3. OEM Revision: An OEM-supplied revision number. Larger numbers are assumed to be newer revisions. For OEMs, good practices will ensure consistency when assigning OEMID and OEM Table ID fields in any table. The intent of these fields is to allow for a binary control system that support services can use. Because many support function can be automated, it is useful when a tool can programatically determine which table release is a compatible and more recent revision of a prior table on the same OEMID and OEM Table ID. The facility can now be used by the vendors to upgrade wrong tables for bug fixing purpose, thus lockdep disabling taint is not suitable for it and it should be a default 'y' option to implement the spec encouraged use case. Note that, by implementing table upgrade inside of ACPICA itself, it is possible to remove acpi_table_initrd_override() and tables can be upgraded by acpi_install_table() automatically. Though current ACPICA impelentation hasn't implemented this, this patched changes the table flag setting timing to allow this to be implemented in ACPICA without changing the code here. Documentation of initrd override mechanism is upgraded accordingly. Original-by: Octavian Purdila <octavian.purdila@intel.com> Signed-off-by: Lv Zheng <lv.zheng@intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-04-11 10:13:33 +08:00
config ACPI_TABLE_UPGRADE
bool "Allow upgrading ACPI tables via initrd"
depends on BLK_DEV_INITRD && ARCH_HAS_ACPI_TABLE_UPGRADE
ACPI / tables: Convert initrd table override to table upgrade mechanism This patch converts the initrd table override mechanism to the table upgrade mechanism by restricting its usage to the tables released with compatibility and more recent revision. This use case has been encouraged by the ACPI specification: 1. OEMID: An OEM-supplied string that identifies the OEM. 2. OEM Table ID: An OEM-supplied string that the OEM uses to identify the particular data table. This field is particularly useful when defining a definition block to distinguish definition block functions. OEM assigns each dissimilar table a new OEM Table Id. 3. OEM Revision: An OEM-supplied revision number. Larger numbers are assumed to be newer revisions. For OEMs, good practices will ensure consistency when assigning OEMID and OEM Table ID fields in any table. The intent of these fields is to allow for a binary control system that support services can use. Because many support function can be automated, it is useful when a tool can programatically determine which table release is a compatible and more recent revision of a prior table on the same OEMID and OEM Table ID. The facility can now be used by the vendors to upgrade wrong tables for bug fixing purpose, thus lockdep disabling taint is not suitable for it and it should be a default 'y' option to implement the spec encouraged use case. Note that, by implementing table upgrade inside of ACPICA itself, it is possible to remove acpi_table_initrd_override() and tables can be upgraded by acpi_install_table() automatically. Though current ACPICA impelentation hasn't implemented this, this patched changes the table flag setting timing to allow this to be implemented in ACPICA without changing the code here. Documentation of initrd override mechanism is upgraded accordingly. Original-by: Octavian Purdila <octavian.purdila@intel.com> Signed-off-by: Lv Zheng <lv.zheng@intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-04-11 10:13:33 +08:00
default y
help
ACPI / tables: Convert initrd table override to table upgrade mechanism This patch converts the initrd table override mechanism to the table upgrade mechanism by restricting its usage to the tables released with compatibility and more recent revision. This use case has been encouraged by the ACPI specification: 1. OEMID: An OEM-supplied string that identifies the OEM. 2. OEM Table ID: An OEM-supplied string that the OEM uses to identify the particular data table. This field is particularly useful when defining a definition block to distinguish definition block functions. OEM assigns each dissimilar table a new OEM Table Id. 3. OEM Revision: An OEM-supplied revision number. Larger numbers are assumed to be newer revisions. For OEMs, good practices will ensure consistency when assigning OEMID and OEM Table ID fields in any table. The intent of these fields is to allow for a binary control system that support services can use. Because many support function can be automated, it is useful when a tool can programatically determine which table release is a compatible and more recent revision of a prior table on the same OEMID and OEM Table ID. The facility can now be used by the vendors to upgrade wrong tables for bug fixing purpose, thus lockdep disabling taint is not suitable for it and it should be a default 'y' option to implement the spec encouraged use case. Note that, by implementing table upgrade inside of ACPICA itself, it is possible to remove acpi_table_initrd_override() and tables can be upgraded by acpi_install_table() automatically. Though current ACPICA impelentation hasn't implemented this, this patched changes the table flag setting timing to allow this to be implemented in ACPICA without changing the code here. Documentation of initrd override mechanism is upgraded accordingly. Original-by: Octavian Purdila <octavian.purdila@intel.com> Signed-off-by: Lv Zheng <lv.zheng@intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-04-11 10:13:33 +08:00
This option provides functionality to upgrade arbitrary ACPI tables
via initrd. No functional change if no ACPI tables are passed via
initrd, therefore it's safe to say Y.
See Documentation/acpi/initrd_table_override.txt for details
config ACPI_DEBUG
bool "Debug Statements"
help
The ACPI subsystem can produce debug output. Saying Y enables this
output and increases the kernel size by around 50K.
Use the acpi.debug_layer and acpi.debug_level kernel command-line
parameters documented in Documentation/acpi/debug.txt and
Documentation/admin-guide/kernel-parameters.rst to control the type and
amount of debug output.
config ACPI_PCI_SLOT
bool "PCI slot detection driver"
depends on SYSFS
help
This driver creates entries in /sys/bus/pci/slots/ for all PCI
slots in the system. This can help correlate PCI bus addresses,
i.e., segment/bus/device/function tuples, with physical slots in
the system. If you are unsure, say N.
config ACPI_CONTAINER
Driver core patches for 3.9-rc1 Here is the big driver core merge for 3.9-rc1 There are two major series here, both of which touch lots of drivers all over the kernel, and will cause you some merge conflicts: - add a new function called devm_ioremap_resource() to properly be able to check return values. - remove CONFIG_EXPERIMENTAL If you need me to provide a merged tree to handle these resolutions, please let me know. Other than those patches, there's not much here, some minor fixes and updates. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.19 (GNU/Linux) iEYEABECAAYFAlEmV0cACgkQMUfUDdst+yncCQCfbmnQZju7kzWXk6PjdFuKspT9 weAAoMCzcAtEzzc4LXuUxxG/sXBVBCjW =yWAQ -----END PGP SIGNATURE----- Merge tag 'driver-core-3.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core Pull driver core patches from Greg Kroah-Hartman: "Here is the big driver core merge for 3.9-rc1 There are two major series here, both of which touch lots of drivers all over the kernel, and will cause you some merge conflicts: - add a new function called devm_ioremap_resource() to properly be able to check return values. - remove CONFIG_EXPERIMENTAL Other than those patches, there's not much here, some minor fixes and updates" Fix up trivial conflicts * tag 'driver-core-3.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (221 commits) base: memory: fix soft/hard_offline_page permissions drivercore: Fix ordering between deferred_probe and exiting initcalls backlight: fix class_find_device() arguments TTY: mark tty_get_device call with the proper const values driver-core: constify data for class_find_device() firmware: Ignore abort check when no user-helper is used firmware: Reduce ifdef CONFIG_FW_LOADER_USER_HELPER firmware: Make user-mode helper optional firmware: Refactoring for splitting user-mode helper code Driver core: treat unregistered bus_types as having no devices watchdog: Convert to devm_ioremap_resource() thermal: Convert to devm_ioremap_resource() spi: Convert to devm_ioremap_resource() power: Convert to devm_ioremap_resource() mtd: Convert to devm_ioremap_resource() mmc: Convert to devm_ioremap_resource() mfd: Convert to devm_ioremap_resource() media: Convert to devm_ioremap_resource() iommu: Convert to devm_ioremap_resource() drm: Convert to devm_ioremap_resource() ...
2013-02-22 04:05:51 +08:00
bool "Container and Module Devices"
default (ACPI_HOTPLUG_MEMORY || ACPI_HOTPLUG_CPU)
help
This driver supports ACPI Container and Module devices (IDs
ACPI0004, PNP0A05, and PNP0A06).
This helps support hotplug of nodes, CPUs, and memory.
To compile this driver as a module, choose M here:
the module will be called container.
config ACPI_HOTPLUG_MEMORY
bool "Memory Hotplug"
depends on MEMORY_HOTPLUG
help
This driver supports ACPI memory hotplug. The driver
fields notifications on ACPI memory devices (PNP0C80),
which represent memory ranges that may be onlined or
offlined during runtime.
If your hardware and firmware do not support adding or
removing memory devices at runtime, you need not enable
this driver.
To compile this driver as a module, choose M here:
the module will be called acpi_memhotplug.
config ACPI_HOTPLUG_IOAPIC
bool
depends on PCI
depends on X86_IO_APIC
default y
config ACPI_SBS
tristate "Smart Battery System"
depends on X86
select POWER_SUPPLY
help
This driver supports the Smart Battery System, another
type of access to battery information, found on some laptops.
To compile this driver as a module, choose M here:
the modules will be called sbs and sbshc.
config ACPI_HED
tristate "Hardware Error Device"
help
This driver supports the Hardware Error Device (PNP0C33),
which is used to report some hardware errors notified via
SCI, mainly the corrected errors.
config ACPI_CUSTOM_METHOD
tristate "Allow ACPI methods to be inserted/replaced at run time"
depends on DEBUG_FS
help
This debug facility allows ACPI AML methods to be inserted and/or
replaced without rebooting the system. For details refer to:
Documentation/acpi/method-customizing.txt.
NOTE: This option is security sensitive, because it allows arbitrary
kernel memory to be written to by root (uid=0) users, allowing them
to bypass certain security measures (e.g. if root is not allowed to
load additional kernel modules after boot, this feature may be used
to override that restriction).
config ACPI_BGRT
bool "Boottime Graphics Resource Table support"
depends on EFI && (X86 || ARM64)
help
This driver adds support for exposing the ACPI Boottime Graphics
Resource Table, which allows the operating system to obtain
data from the firmware boot splash. It will appear under
/sys/firmware/acpi/bgrt/ .
config ACPI_REDUCED_HARDWARE_ONLY
bool "Hardware-reduced ACPI support only" if EXPERT
def_bool n
help
This config item changes the way the ACPI code is built. When this
option is selected, the kernel will use a specialized version of
ACPICA that ONLY supports the ACPI "reduced hardware" mode. The
resulting kernel will be smaller but it will also be restricted to
running in ACPI reduced hardware mode ONLY.
If you are unsure what to do, do not enable this option.
source "drivers/acpi/nfit/Kconfig"
2015-06-09 02:27:06 +08:00
source "drivers/acpi/apei/Kconfig"
source "drivers/acpi/dptf/Kconfig"
config ACPI_WATCHDOG
bool
config ACPI_EXTLOG
tristate "Extended Error Log support"
depends on X86_MCE && X86_LOCAL_APIC && EDAC
select UEFI_CPER
help
Certain usages such as Predictive Failure Analysis (PFA) require
more information about the error than what can be described in
processor machine check banks. Most server processors log
additional information about the error in processor uncore
registers. Since the addresses and layout of these registers vary
widely from one processor to another, system software cannot
readily make use of them. To complicate matters further, some of
the additional error information cannot be constructed without
detailed knowledge about platform topology.
Enhanced MCA Logging allows firmware to provide additional error
information to system software, synchronous with MCE or CMCI. This
driver adds support for that functionality with corresponding
tracepoint which carries that information to userspace.
config ACPI_ADXL
bool
menuconfig PMIC_OPREGION
bool "PMIC (Power Management Integrated Circuit) operation region support"
help
Select this option to enable support for ACPI operation
region of the PMIC chip. The operation region can be used
to control power rails and sensor reading/writing on the
PMIC chip.
if PMIC_OPREGION
config CRC_PMIC_OPREGION
bool "ACPI operation region support for CrystalCove PMIC"
depends on INTEL_SOC_PMIC
help
This config adds ACPI operation region support for CrystalCove PMIC.
config XPOWER_PMIC_OPREGION
bool "ACPI operation region support for XPower AXP288 PMIC"
depends on MFD_AXP20X_I2C && IOSF_MBI
help
This config adds ACPI operation region support for XPower AXP288 PMIC.
config BXT_WC_PMIC_OPREGION
bool "ACPI operation region support for BXT WhiskeyCove PMIC"
depends on INTEL_SOC_PMIC_BXTWC
help
This config adds ACPI operation region support for BXT WhiskeyCove PMIC.
config CHT_WC_PMIC_OPREGION
bool "ACPI operation region support for CHT Whiskey Cove PMIC"
depends on INTEL_SOC_PMIC_CHTWC
help
This config adds ACPI operation region support for CHT Whiskey Cove PMIC.
config CHT_DC_TI_PMIC_OPREGION
bool "ACPI operation region support for Dollar Cove TI PMIC"
depends on INTEL_SOC_PMIC_CHTDC_TI
help
This config adds ACPI operation region support for Dollar Cove TI PMIC.
endif
config ACPI_CONFIGFS
tristate "ACPI configfs support"
select CONFIGFS_FS
help
Select this option to enable support for ACPI configuration from
userspace. The configurable ACPI groups will be visible under
/config/acpi, assuming configfs is mounted under /config.
ACPI: I/O Remapping Table (IORT) initial support IORT shows representation of IO topology for ARM based systems. It describes how various components are connected together on parent-child basis e.g. PCI RC -> SMMU -> ITS. Also see IORT spec. http://infocenter.arm.com/help/topic/com.arm.doc.den0049b/DEN0049B_IO_Remapping_Table.pdf Initial support allows to detect IORT table presence and save its root pointer obtained through acpi_get_table(). The pointer validity depends on acpi_gbl_permanent_mmap because if acpi_gbl_permanent_mmap is not set while using IORT nodes we would dereference unmapped pointers. For the aforementioned reason call acpi_iort_init() from acpi_init() which guarantees acpi_gbl_permanent_mmap to be set at that point. Add generic helpers which are helpful for scanning and retrieving information from IORT table content. List of the most important helpers: - iort_find_dev_node() finds IORT node for a given device - iort_node_map_rid() maps device RID and returns IORT node which provides final translation IORT support is placed under drivers/acpi/arm64/ new directory due to its ARM64 specific nature. The code there is considered only for ARM64. The long term plan is to keep all ARM64 specific tables support in this place e.g. GTDT table. Signed-off-by: Tomasz Nowicki <tn@semihalf.com> Acked-by: Rafael J. Wysocki <rjw@rjwysocki.net> Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org> Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2016-09-13 02:54:20 +08:00
if ARM64
source "drivers/acpi/arm64/Kconfig"
config ACPI_PPTT
bool
ACPI: I/O Remapping Table (IORT) initial support IORT shows representation of IO topology for ARM based systems. It describes how various components are connected together on parent-child basis e.g. PCI RC -> SMMU -> ITS. Also see IORT spec. http://infocenter.arm.com/help/topic/com.arm.doc.den0049b/DEN0049B_IO_Remapping_Table.pdf Initial support allows to detect IORT table presence and save its root pointer obtained through acpi_get_table(). The pointer validity depends on acpi_gbl_permanent_mmap because if acpi_gbl_permanent_mmap is not set while using IORT nodes we would dereference unmapped pointers. For the aforementioned reason call acpi_iort_init() from acpi_init() which guarantees acpi_gbl_permanent_mmap to be set at that point. Add generic helpers which are helpful for scanning and retrieving information from IORT table content. List of the most important helpers: - iort_find_dev_node() finds IORT node for a given device - iort_node_map_rid() maps device RID and returns IORT node which provides final translation IORT support is placed under drivers/acpi/arm64/ new directory due to its ARM64 specific nature. The code there is considered only for ARM64. The long term plan is to keep all ARM64 specific tables support in this place e.g. GTDT table. Signed-off-by: Tomasz Nowicki <tn@semihalf.com> Acked-by: Rafael J. Wysocki <rjw@rjwysocki.net> Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org> Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2016-09-13 02:54:20 +08:00
endif
config TPS68470_PMIC_OPREGION
bool "ACPI operation region support for TPS68470 PMIC"
depends on MFD_TPS68470
help
This config adds ACPI operation region support for TI TPS68470 PMIC.
TPS68470 device is an advanced power management unit that powers
a Compact Camera Module (CCM), generates clocks for image sensors,
drives a dual LED for flash and incorporates two LED drivers for
general purpose indicators.
This driver enables ACPI operation region support control voltage
regulators and clocks.
This option is a bool as it provides an ACPI operation
region, which must be available before any of the devices
using this, are probed.
endif # ACPI
config X86_PM_TIMER
bool "Power Management Timer Support" if EXPERT
depends on X86 && (ACPI || JAILHOUSE_GUEST)
default y
help
The Power Management Timer is available on all ACPI-capable,
in most cases even if ACPI is unusable or blacklisted.
This timing source is not affected by power management features
like aggressive processor idling, throttling, frequency and/or
voltage scaling, unlike the commonly used Time Stamp Counter
(TSC) timing source.
You should nearly always say Y here because many modern
systems require this timer.