From 5a7ea52b6faec6f8877e49645a80349b2d970f0a Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Tue, 11 Feb 2020 23:58:17 +0100 Subject: PM: QoS: Drop pm_qos_update_request_timeout() The pm_qos_update_request_timeout() function is not called from anywhere, so drop it along with the work member in struct pm_qos_request needed by it. Also drop the useless pm_qos_update_request_timeout trace event that is only triggered by that function (so it never triggers at all) and update the trace events documentation accordingly. Signed-off-by: Rafael J. Wysocki Reviewed-by: Ulf Hansson Reviewed-by: Amit Kucheria Tested-by: Amit Kucheria --- Documentation/trace/events-power.rst | 2 -- 1 file changed, 2 deletions(-) (limited to 'Documentation') diff --git a/Documentation/trace/events-power.rst b/Documentation/trace/events-power.rst index 2ef318962e29..eec7453a168e 100644 --- a/Documentation/trace/events-power.rst +++ b/Documentation/trace/events-power.rst @@ -78,11 +78,9 @@ target/flags update. pm_qos_add_request "pm_qos_class=%s value=%d" pm_qos_update_request "pm_qos_class=%s value=%d" pm_qos_remove_request "pm_qos_class=%s value=%d" - pm_qos_update_request_timeout "pm_qos_class=%s value=%d, timeout_us=%ld" The first parameter gives the QoS class name (e.g. "CPU_DMA_LATENCY"). The second parameter is value to be added/updated/removed. -The third parameter is timeout value in usec. :: pm_qos_update_target "action=%s prev_value=%d curr_value=%d" -- cgit v1.2.3 From 333eed7d20069e2d80446f5fdf9ac3868b55e7b9 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Wed, 12 Feb 2020 00:06:17 +0100 Subject: PM: QoS: Simplify definitions of CPU latency QoS trace events Modify the definitions of the CPU latency QoS trace events to take one argument (since PM_QOS_CPU_DMA_LATENCY is always passed as the pm_qos_class argument to them) and update the documentation of them accordingly (while at it, make it explicitly mention CPU latency QoS and relocate it after the device PM QoS trace events documentation). The names and output format of the trace events do not change to preserve user space compatibility. No intentional functional impact. Signed-off-by: Rafael J. Wysocki Reviewed-by: Ulf Hansson Reviewed-by: Amit Kucheria Tested-by: Amit Kucheria --- Documentation/trace/events-power.rst | 19 ++++++++++--------- include/trace/events/power.h | 35 +++++++++++++++++------------------ kernel/power/qos.c | 16 ++++++++-------- 3 files changed, 35 insertions(+), 35 deletions(-) (limited to 'Documentation') diff --git a/Documentation/trace/events-power.rst b/Documentation/trace/events-power.rst index eec7453a168e..f45bf11fa88d 100644 --- a/Documentation/trace/events-power.rst +++ b/Documentation/trace/events-power.rst @@ -73,14 +73,6 @@ The second parameter is the power domain target state. ================ The PM QoS events are used for QoS add/update/remove request and for target/flags update. -:: - - pm_qos_add_request "pm_qos_class=%s value=%d" - pm_qos_update_request "pm_qos_class=%s value=%d" - pm_qos_remove_request "pm_qos_class=%s value=%d" - -The first parameter gives the QoS class name (e.g. "CPU_DMA_LATENCY"). -The second parameter is value to be added/updated/removed. :: pm_qos_update_target "action=%s prev_value=%d curr_value=%d" @@ -90,7 +82,7 @@ The first parameter gives the QoS action name (e.g. "ADD_REQ"). The second parameter is the previous QoS value. The third parameter is the current QoS value to update. -And, there are also events used for device PM QoS add/update/remove request. +There are also events used for device PM QoS add/update/remove request. :: dev_pm_qos_add_request "device=%s type=%s new_value=%d" @@ -101,3 +93,12 @@ The first parameter gives the device name which tries to add/update/remove QoS requests. The second parameter gives the request type (e.g. "DEV_PM_QOS_RESUME_LATENCY"). The third parameter is value to be added/updated/removed. + +And, there are events used for CPU latency QoS add/update/remove request. +:: + + pm_qos_add_request "value=%d" + pm_qos_update_request "value=%d" + pm_qos_remove_request "value=%d" + +The parameter is the value to be added/updated/removed. diff --git a/include/trace/events/power.h b/include/trace/events/power.h index ecf39daabf16..af5018aa9517 100644 --- a/include/trace/events/power.h +++ b/include/trace/events/power.h @@ -359,51 +359,50 @@ DEFINE_EVENT(power_domain, power_domain_target, ); /* - * The pm qos events are used for pm qos update + * CPU latency QoS events used for global CPU latency QoS list updates */ -DECLARE_EVENT_CLASS(pm_qos_request, +DECLARE_EVENT_CLASS(cpu_latency_qos_request, - TP_PROTO(int pm_qos_class, s32 value), + TP_PROTO(s32 value), - TP_ARGS(pm_qos_class, value), + TP_ARGS(value), TP_STRUCT__entry( - __field( int, pm_qos_class ) __field( s32, value ) ), TP_fast_assign( - __entry->pm_qos_class = pm_qos_class; __entry->value = value; ), - TP_printk("pm_qos_class=%s value=%d", - __print_symbolic(__entry->pm_qos_class, - { PM_QOS_CPU_DMA_LATENCY, "CPU_DMA_LATENCY" }), + TP_printk("CPU_DMA_LATENCY value=%d", __entry->value) ); -DEFINE_EVENT(pm_qos_request, pm_qos_add_request, +DEFINE_EVENT(cpu_latency_qos_request, pm_qos_add_request, - TP_PROTO(int pm_qos_class, s32 value), + TP_PROTO(s32 value), - TP_ARGS(pm_qos_class, value) + TP_ARGS(value) ); -DEFINE_EVENT(pm_qos_request, pm_qos_update_request, +DEFINE_EVENT(cpu_latency_qos_request, pm_qos_update_request, - TP_PROTO(int pm_qos_class, s32 value), + TP_PROTO(s32 value), - TP_ARGS(pm_qos_class, value) + TP_ARGS(value) ); -DEFINE_EVENT(pm_qos_request, pm_qos_remove_request, +DEFINE_EVENT(cpu_latency_qos_request, pm_qos_remove_request, - TP_PROTO(int pm_qos_class, s32 value), + TP_PROTO(s32 value), - TP_ARGS(pm_qos_class, value) + TP_ARGS(value) ); +/* + * General PM QoS events used for updates of PM QoS request lists + */ DECLARE_EVENT_CLASS(pm_qos_update, TP_PROTO(enum pm_qos_req_action action, int prev_value, int curr_value), diff --git a/kernel/power/qos.c b/kernel/power/qos.c index a6bf53e9db17..afac7010e0f2 100644 --- a/kernel/power/qos.c +++ b/kernel/power/qos.c @@ -247,8 +247,8 @@ int pm_qos_request_active(struct pm_qos_request *req) } EXPORT_SYMBOL_GPL(pm_qos_request_active); -static void cpu_latency_qos_update(struct pm_qos_request *req, - enum pm_qos_req_action action, s32 value) +static void cpu_latency_qos_apply(struct pm_qos_request *req, + enum pm_qos_req_action action, s32 value) { int ret = pm_qos_update_target(req->qos, &req->node, action, value); if (ret > 0) @@ -278,10 +278,10 @@ void pm_qos_add_request(struct pm_qos_request *req, return; } - trace_pm_qos_add_request(PM_QOS_CPU_DMA_LATENCY, value); + trace_pm_qos_add_request(value); req->qos = &cpu_latency_constraints; - cpu_latency_qos_update(req, PM_QOS_ADD_REQ, value); + cpu_latency_qos_apply(req, PM_QOS_ADD_REQ, value); } EXPORT_SYMBOL_GPL(pm_qos_add_request); @@ -305,12 +305,12 @@ void pm_qos_update_request(struct pm_qos_request *req, s32 new_value) return; } - trace_pm_qos_update_request(PM_QOS_CPU_DMA_LATENCY, new_value); + trace_pm_qos_update_request(new_value); if (new_value == req->node.prio) return; - cpu_latency_qos_update(req, PM_QOS_UPDATE_REQ, new_value); + cpu_latency_qos_apply(req, PM_QOS_UPDATE_REQ, new_value); } EXPORT_SYMBOL_GPL(pm_qos_update_request); @@ -333,9 +333,9 @@ void pm_qos_remove_request(struct pm_qos_request *req) return; } - trace_pm_qos_remove_request(PM_QOS_CPU_DMA_LATENCY, PM_QOS_DEFAULT_VALUE); + trace_pm_qos_remove_request(PM_QOS_DEFAULT_VALUE); - cpu_latency_qos_update(req, PM_QOS_REMOVE_REQ, PM_QOS_DEFAULT_VALUE); + cpu_latency_qos_apply(req, PM_QOS_REMOVE_REQ, PM_QOS_DEFAULT_VALUE); memset(req, 0, sizeof(*req)); } EXPORT_SYMBOL_GPL(pm_qos_remove_request); -- cgit v1.2.3 From b8e6e27c626e60bb5708ce8c974b58c485c32ac7 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Wed, 12 Feb 2020 00:36:35 +0100 Subject: Documentation: PM: QoS: Update to reflect previous code changes Update the PM QoS documentation to reflect the previous code changes regarding the removal of PM QoS classes and the CPU latency QoS API rework. Signed-off-by: Rafael J. Wysocki Reviewed-by: Ulf Hansson Reviewed-by: Amit Kucheria Tested-by: Amit Kucheria --- Documentation/admin-guide/pm/cpuidle.rst | 73 +++++++++++++-------------- Documentation/power/pm_qos_interface.rst | 86 +++++++++++++++----------------- 2 files changed, 75 insertions(+), 84 deletions(-) (limited to 'Documentation') diff --git a/Documentation/admin-guide/pm/cpuidle.rst b/Documentation/admin-guide/pm/cpuidle.rst index 6a06dc473dd6..5605cc6f9560 100644 --- a/Documentation/admin-guide/pm/cpuidle.rst +++ b/Documentation/admin-guide/pm/cpuidle.rst @@ -583,20 +583,17 @@ Power Management Quality of Service for CPUs The power management quality of service (PM QoS) framework in the Linux kernel allows kernel code and user space processes to set constraints on various energy-efficiency features of the kernel to prevent performance from dropping -below a required level. The PM QoS constraints can be set globally, in -predefined categories referred to as PM QoS classes, or against individual -devices. +below a required level. CPU idle time management can be affected by PM QoS in two ways, through the -global constraint in the ``PM_QOS_CPU_DMA_LATENCY`` class and through the -resume latency constraints for individual CPUs. Kernel code (e.g. device -drivers) can set both of them with the help of special internal interfaces -provided by the PM QoS framework. User space can modify the former by opening -the :file:`cpu_dma_latency` special device file under :file:`/dev/` and writing -a binary value (interpreted as a signed 32-bit integer) to it. In turn, the -resume latency constraint for a CPU can be modified by user space by writing a -string (representing a signed 32-bit integer) to the -:file:`power/pm_qos_resume_latency_us` file under +global CPU latency limit and through the resume latency constraints for +individual CPUs. Kernel code (e.g. device drivers) can set both of them with +the help of special internal interfaces provided by the PM QoS framework. User +space can modify the former by opening the :file:`cpu_dma_latency` special +device file under :file:`/dev/` and writing a binary value (interpreted as a +signed 32-bit integer) to it. In turn, the resume latency constraint for a CPU +can be modified from user space by writing a string (representing a signed +32-bit integer) to the :file:`power/pm_qos_resume_latency_us` file under :file:`/sys/devices/system/cpu/cpu/` in ``sysfs``, where the CPU number ```` is allocated at the system initialization time. Negative values will be rejected in both cases and, also in both cases, the written integer @@ -605,32 +602,34 @@ number will be interpreted as a requested PM QoS constraint in microseconds. The requested value is not automatically applied as a new constraint, however, as it may be less restrictive (greater in this particular case) than another constraint previously requested by someone else. For this reason, the PM QoS -framework maintains a list of requests that have been made so far in each -global class and for each device, aggregates them and applies the effective -(minimum in this particular case) value as the new constraint. +framework maintains a list of requests that have been made so far for the +global CPU latency limit and for each individual CPU, aggregates them and +applies the effective (minimum in this particular case) value as the new +constraint. In fact, opening the :file:`cpu_dma_latency` special device file causes a new -PM QoS request to be created and added to the priority list of requests in the -``PM_QOS_CPU_DMA_LATENCY`` class and the file descriptor coming from the -"open" operation represents that request. If that file descriptor is then -used for writing, the number written to it will be associated with the PM QoS -request represented by it as a new requested constraint value. Next, the -priority list mechanism will be used to determine the new effective value of -the entire list of requests and that effective value will be set as a new -constraint. Thus setting a new requested constraint value will only change the -real constraint if the effective "list" value is affected by it. In particular, -for the ``PM_QOS_CPU_DMA_LATENCY`` class it only affects the real constraint if -it is the minimum of the requested constraints in the list. The process holding -a file descriptor obtained by opening the :file:`cpu_dma_latency` special device -file controls the PM QoS request associated with that file descriptor, but it -controls this particular PM QoS request only. +PM QoS request to be created and added to a global priority list of CPU latency +limit requests and the file descriptor coming from the "open" operation +represents that request. If that file descriptor is then used for writing, the +number written to it will be associated with the PM QoS request represented by +it as a new requested limit value. Next, the priority list mechanism will be +used to determine the new effective value of the entire list of requests and +that effective value will be set as a new CPU latency limit. Thus requesting a +new limit value will only change the real limit if the effective "list" value is +affected by it, which is the case if it is the minimum of the requested values +in the list. + +The process holding a file descriptor obtained by opening the +:file:`cpu_dma_latency` special device file controls the PM QoS request +associated with that file descriptor, but it controls this particular PM QoS +request only. Closing the :file:`cpu_dma_latency` special device file or, more precisely, the file descriptor obtained while opening it, causes the PM QoS request associated -with that file descriptor to be removed from the ``PM_QOS_CPU_DMA_LATENCY`` -class priority list and destroyed. If that happens, the priority list mechanism -will be used, again, to determine the new effective value for the whole list -and that value will become the new real constraint. +with that file descriptor to be removed from the global priority list of CPU +latency limit requests and destroyed. If that happens, the priority list +mechanism will be used again, to determine the new effective value for the whole +list and that value will become the new limit. In turn, for each CPU there is one resume latency PM QoS request associated with the :file:`power/pm_qos_resume_latency_us` file under @@ -647,10 +646,10 @@ CPU in question every time the list of requests is updated this way or another (there may be other requests coming from kernel code in that list). CPU idle time governors are expected to regard the minimum of the global -effective ``PM_QOS_CPU_DMA_LATENCY`` class constraint and the effective -resume latency constraint for the given CPU as the upper limit for the exit -latency of the idle states they can select for that CPU. They should never -select any idle states with exit latency beyond that limit. +(effective) CPU latency limit and the effective resume latency constraint for +the given CPU as the upper limit for the exit latency of the idle states that +they are allowed to select for that CPU. They should never select any idle +states with exit latency beyond that limit. Idle States Control Via Kernel Command Line diff --git a/Documentation/power/pm_qos_interface.rst b/Documentation/power/pm_qos_interface.rst index 0d62d506caf0..064f668fbdab 100644 --- a/Documentation/power/pm_qos_interface.rst +++ b/Documentation/power/pm_qos_interface.rst @@ -7,86 +7,78 @@ performance expectations by drivers, subsystems and user space applications on one of the parameters. Two different PM QoS frameworks are available: -1. PM QoS classes for cpu_dma_latency +1. CPU latency QoS. 2. The per-device PM QoS framework provides the API to manage the per-device latency constraints and PM QoS flags. -Each parameters have defined units: - - * latency: usec - * timeout: usec - * throughput: kbs (kilo bit / sec) - * memory bandwidth: mbs (mega bit / sec) +The latency unit used in the PM QoS framework is the microsecond (usec). 1. PM QoS framework =================== -The infrastructure exposes multiple misc device nodes one per implemented -parameter. The set of parameters implement is defined by pm_qos_power_init() -and pm_qos_params.h. This is done because having the available parameters -being runtime configurable or changeable from a driver was seen as too easy to -abuse. - -For each parameter a list of performance requests is maintained along with -an aggregated target value. The aggregated target value is updated with -changes to the request list or elements of the list. Typically the -aggregated target value is simply the max or min of the request values held -in the parameter list elements. +A global list of CPU latency QoS requests is maintained along with an aggregated +(effective) target value. The aggregated target value is updated with changes +to the request list or elements of the list. For CPU latency QoS, the +aggregated target value is simply the min of the request values held in the list +elements. + Note: the aggregated target value is implemented as an atomic variable so that reading the aggregated value does not require any locking mechanism. +From kernel space the use of this interface is simple: -From kernel mode the use of this interface is simple: - -void pm_qos_add_request(handle, param_class, target_value): - Will insert an element into the list for that identified PM QoS class with the - target value. Upon change to this list the new target is recomputed and any - registered notifiers are called only if the target value is now different. - Clients of pm_qos need to save the returned handle for future use in other - pm_qos API functions. +void cpu_latency_qos_add_request(handle, target_value): + Will insert an element into the CPU latency QoS list with the target value. + Upon change to this list the new target is recomputed and any registered + notifiers are called only if the target value is now different. + Clients of PM QoS need to save the returned handle for future use in other + PM QoS API functions. -void pm_qos_update_request(handle, new_target_value): +void cpu_latency_qos_update_request(handle, new_target_value): Will update the list element pointed to by the handle with the new target value and recompute the new aggregated target, calling the notification tree if the target is changed. -void pm_qos_remove_request(handle): +void cpu_latency_qos_remove_request(handle): Will remove the element. After removal it will update the aggregate target and call the notification tree if the target was changed as a result of removing the request. -int pm_qos_request(param_class): - Returns the aggregated value for a given PM QoS class. +int cpu_latency_qos_limit(): + Returns the aggregated value for the CPU latency QoS. + +int cpu_latency_qos_request_active(handle): + Returns if the request is still active, i.e. it has not been removed from the + CPU latency QoS list. -int pm_qos_request_active(handle): - Returns if the request is still active, i.e. it has not been removed from a - PM QoS class constraints list. +int cpu_latency_qos_add_notifier(notifier): + Adds a notification callback function to the CPU latency QoS. The callback is + called when the aggregated value for the CPU latency QoS is changed. -int pm_qos_add_notifier(param_class, notifier): - Adds a notification callback function to the PM QoS class. The callback is - called when the aggregated value for the PM QoS class is changed. +int cpu_latency_qos_remove_notifier(notifier): + Removes the notification callback function from the CPU latency QoS. -int pm_qos_remove_notifier(int param_class, notifier): - Removes the notification callback function for the PM QoS class. +From user space: -From user mode: +The infrastructure exposes one device node, /dev/cpu_dma_latency, for the CPU +latency QoS. -Only processes can register a pm_qos request. To provide for automatic +Only processes can register a PM QoS request. To provide for automatic cleanup of a process, the interface requires the process to register its -parameter requests in the following way: +parameter requests as follows. -To register the default pm_qos target for the specific parameter, the process -must open /dev/cpu_dma_latency +To register the default PM QoS target for the CPU latency QoS, the process must +open /dev/cpu_dma_latency. As long as the device node is held open that process has a registered request on the parameter. -To change the requested target value the process needs to write an s32 value to -the open device node. Alternatively the user mode program could write a hex -string for the value using 10 char long format e.g. "0x12345678". This -translates to a pm_qos_update_request call. +To change the requested target value, the process needs to write an s32 value to +the open device node. Alternatively, it can write a hex string for the value +using the 10 char long format e.g. "0x12345678". This translates to a +cpu_latency_qos_update_request() call. To remove the user mode request for a target value simply close the device node. -- cgit v1.2.3 From 3c87402771f2bc38ee92eb506bb58e4fc4a5b8b9 Mon Sep 17 00:00:00 2001 From: Randy Dunlap Date: Sun, 16 Feb 2020 20:54:21 -0800 Subject: Documentation: power: fix pm_qos_interface.rst format warning Fix Sphinx warnings by indenting the bullet list (and making it unnumbered). Documentation/power/pm_qos_interface.rst:12: WARNING: Unexpected indentation. Signed-off-by: Randy Dunlap Signed-off-by: Rafael J. Wysocki --- Documentation/power/pm_qos_interface.rst | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'Documentation') diff --git a/Documentation/power/pm_qos_interface.rst b/Documentation/power/pm_qos_interface.rst index 064f668fbdab..69b0fe3e2542 100644 --- a/Documentation/power/pm_qos_interface.rst +++ b/Documentation/power/pm_qos_interface.rst @@ -7,8 +7,8 @@ performance expectations by drivers, subsystems and user space applications on one of the parameters. Two different PM QoS frameworks are available: -1. CPU latency QoS. -2. The per-device PM QoS framework provides the API to manage the + * CPU latency QoS. + * The per-device PM QoS framework provides the API to manage the per-device latency constraints and PM QoS flags. The latency unit used in the PM QoS framework is the microsecond (usec). -- cgit v1.2.3 From 03b22496502dacb8a4f3b65e08fcde1d606cbff2 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Thu, 27 Feb 2020 23:30:48 +0100 Subject: Documentation: cpufreq: Move legacy driver documentation There are three legacy driver documents in Documentation/cpu-freq/ that were added years ago and converting them each to the .rst format is rather pointless, even though there is some value in preserving them. However, if they are preserved, they need to go into the admin-guide part of cpufreq documentation where they belong (at least to a certain extent). To preserve them with minimum amount of changes and put them into the right place, and make it possible to process them into HTML (and other formats) along with the rest of the documentation, move them each as a "literal text" block into a separate section of a single .rst "wrapper" file under Documentation/admin-guide/pm/. While at it, repair the PCC specification URL in one of them. Signed-off-by: Rafael J. Wysocki --- Documentation/admin-guide/pm/cpufreq_drivers.rst | 274 +++++++++++++++++++++++ Documentation/admin-guide/pm/working-state.rst | 1 + Documentation/cpu-freq/amd-powernow.txt | 38 ---- Documentation/cpu-freq/cpufreq-nforce2.txt | 19 -- Documentation/cpu-freq/pcc-cpufreq.txt | 207 ----------------- 5 files changed, 275 insertions(+), 264 deletions(-) create mode 100644 Documentation/admin-guide/pm/cpufreq_drivers.rst delete mode 100644 Documentation/cpu-freq/amd-powernow.txt delete mode 100644 Documentation/cpu-freq/cpufreq-nforce2.txt delete mode 100644 Documentation/cpu-freq/pcc-cpufreq.txt (limited to 'Documentation') diff --git a/Documentation/admin-guide/pm/cpufreq_drivers.rst b/Documentation/admin-guide/pm/cpufreq_drivers.rst new file mode 100644 index 000000000000..9a134ae65803 --- /dev/null +++ b/Documentation/admin-guide/pm/cpufreq_drivers.rst @@ -0,0 +1,274 @@ +.. SPDX-License-Identifier: GPL-2.0 + +======================================================= +Legacy Documentation of CPU Performance Scaling Drivers +======================================================= + +Included below are historic documents describing assorted +:doc:`CPU performance scaling ` drivers. They are reproduced verbatim, +with the original white space formatting and indentation preserved, except for +the added leading space character in every line of text. + + +AMD PowerNow! Drivers +===================== + +:: + + PowerNow! and Cool'n'Quiet are AMD names for frequency + management capabilities in AMD processors. As the hardware + implementation changes in new generations of the processors, + there is a different cpu-freq driver for each generation. + + Note that the driver's will not load on the "wrong" hardware, + so it is safe to try each driver in turn when in doubt as to + which is the correct driver. + + Note that the functionality to change frequency (and voltage) + is not available in all processors. The drivers will refuse + to load on processors without this capability. The capability + is detected with the cpuid instruction. + + The drivers use BIOS supplied tables to obtain frequency and + voltage information appropriate for a particular platform. + Frequency transitions will be unavailable if the BIOS does + not supply these tables. + + 6th Generation: powernow-k6 + + 7th Generation: powernow-k7: Athlon, Duron, Geode. + + 8th Generation: powernow-k8: Athlon, Athlon 64, Opteron, Sempron. + Documentation on this functionality in 8th generation processors + is available in the "BIOS and Kernel Developer's Guide", publication + 26094, in chapter 9, available for download from www.amd.com. + + BIOS supplied data, for powernow-k7 and for powernow-k8, may be + from either the PSB table or from ACPI objects. The ACPI support + is only available if the kernel config sets CONFIG_ACPI_PROCESSOR. + The powernow-k8 driver will attempt to use ACPI if so configured, + and fall back to PST if that fails. + The powernow-k7 driver will try to use the PSB support first, and + fall back to ACPI if the PSB support fails. A module parameter, + acpi_force, is provided to force ACPI support to be used instead + of PSB support. + + +``cpufreq-nforce2`` +=================== + +:: + + The cpufreq-nforce2 driver changes the FSB on nVidia nForce2 platforms. + + This works better than on other platforms, because the FSB of the CPU + can be controlled independently from the PCI/AGP clock. + + The module has two options: + + fid: multiplier * 10 (for example 8.5 = 85) + min_fsb: minimum FSB + + If not set, fid is calculated from the current CPU speed and the FSB. + min_fsb defaults to FSB at boot time - 50 MHz. + + IMPORTANT: The available range is limited downwards! + Also the minimum available FSB can differ, for systems + booting with 200 MHz, 150 should always work. + + +``pcc-cpufreq`` +=============== + +:: + + /* + * pcc-cpufreq.txt - PCC interface documentation + * + * Copyright (C) 2009 Red Hat, Matthew Garrett + * Copyright (C) 2009 Hewlett-Packard Development Company, L.P. + * Nagananda Chumbalkar + */ + + + Processor Clocking Control Driver + --------------------------------- + + Contents: + --------- + 1. Introduction + 1.1 PCC interface + 1.1.1 Get Average Frequency + 1.1.2 Set Desired Frequency + 1.2 Platforms affected + 2. Driver and /sys details + 2.1 scaling_available_frequencies + 2.2 cpuinfo_transition_latency + 2.3 cpuinfo_cur_freq + 2.4 related_cpus + 3. Caveats + + 1. Introduction: + ---------------- + Processor Clocking Control (PCC) is an interface between the platform + firmware and OSPM. It is a mechanism for coordinating processor + performance (ie: frequency) between the platform firmware and the OS. + + The PCC driver (pcc-cpufreq) allows OSPM to take advantage of the PCC + interface. + + OS utilizes the PCC interface to inform platform firmware what frequency the + OS wants for a logical processor. The platform firmware attempts to achieve + the requested frequency. If the request for the target frequency could not be + satisfied by platform firmware, then it usually means that power budget + conditions are in place, and "power capping" is taking place. + + 1.1 PCC interface: + ------------------ + The complete PCC specification is available here: + https://acpica.org/sites/acpica/files/Processor-Clocking-Control-v1p0.pdf + + PCC relies on a shared memory region that provides a channel for communication + between the OS and platform firmware. PCC also implements a "doorbell" that + is used by the OS to inform the platform firmware that a command has been + sent. + + The ACPI PCCH() method is used to discover the location of the PCC shared + memory region. The shared memory region header contains the "command" and + "status" interface. PCCH() also contains details on how to access the platform + doorbell. + + The following commands are supported by the PCC interface: + * Get Average Frequency + * Set Desired Frequency + + The ACPI PCCP() method is implemented for each logical processor and is + used to discover the offsets for the input and output buffers in the shared + memory region. + + When PCC mode is enabled, the platform will not expose processor performance + or throttle states (_PSS, _TSS and related ACPI objects) to OSPM. Therefore, + the native P-state driver (such as acpi-cpufreq for Intel, powernow-k8 for + AMD) will not load. + + However, OSPM remains in control of policy. The governor (eg: "ondemand") + computes the required performance for each processor based on server workload. + The PCC driver fills in the command interface, and the input buffer and + communicates the request to the platform firmware. The platform firmware is + responsible for delivering the requested performance. + + Each PCC command is "global" in scope and can affect all the logical CPUs in + the system. Therefore, PCC is capable of performing "group" updates. With PCC + the OS is capable of getting/setting the frequency of all the logical CPUs in + the system with a single call to the BIOS. + + 1.1.1 Get Average Frequency: + ---------------------------- + This command is used by the OSPM to query the running frequency of the + processor since the last time this command was completed. The output buffer + indicates the average unhalted frequency of the logical processor expressed as + a percentage of the nominal (ie: maximum) CPU frequency. The output buffer + also signifies if the CPU frequency is limited by a power budget condition. + + 1.1.2 Set Desired Frequency: + ---------------------------- + This command is used by the OSPM to communicate to the platform firmware the + desired frequency for a logical processor. The output buffer is currently + ignored by OSPM. The next invocation of "Get Average Frequency" will inform + OSPM if the desired frequency was achieved or not. + + 1.2 Platforms affected: + ----------------------- + The PCC driver will load on any system where the platform firmware: + * supports the PCC interface, and the associated PCCH() and PCCP() methods + * assumes responsibility for managing the hardware clocking controls in order + to deliver the requested processor performance + + Currently, certain HP ProLiant platforms implement the PCC interface. On those + platforms PCC is the "default" choice. + + However, it is possible to disable this interface via a BIOS setting. In + such an instance, as is also the case on platforms where the PCC interface + is not implemented, the PCC driver will fail to load silently. + + 2. Driver and /sys details: + --------------------------- + When the driver loads, it merely prints the lowest and the highest CPU + frequencies supported by the platform firmware. + + The PCC driver loads with a message such as: + pcc-cpufreq: (v1.00.00) driver loaded with frequency limits: 1600 MHz, 2933 + MHz + + This means that the OPSM can request the CPU to run at any frequency in + between the limits (1600 MHz, and 2933 MHz) specified in the message. + + Internally, there is no need for the driver to convert the "target" frequency + to a corresponding P-state. + + The VERSION number for the driver will be of the format v.xy.ab. + eg: 1.00.02 + ----- -- + | | + | -- this will increase with bug fixes/enhancements to the driver + |-- this is the version of the PCC specification the driver adheres to + + + The following is a brief discussion on some of the fields exported via the + /sys filesystem and how their values are affected by the PCC driver: + + 2.1 scaling_available_frequencies: + ---------------------------------- + scaling_available_frequencies is not created in /sys. No intermediate + frequencies need to be listed because the BIOS will try to achieve any + frequency, within limits, requested by the governor. A frequency does not have + to be strictly associated with a P-state. + + 2.2 cpuinfo_transition_latency: + ------------------------------- + The cpuinfo_transition_latency field is 0. The PCC specification does + not include a field to expose this value currently. + + 2.3 cpuinfo_cur_freq: + --------------------- + A) Often cpuinfo_cur_freq will show a value different than what is declared + in the scaling_available_frequencies or scaling_cur_freq, or scaling_max_freq. + This is due to "turbo boost" available on recent Intel processors. If certain + conditions are met the BIOS can achieve a slightly higher speed than requested + by OSPM. An example: + + scaling_cur_freq : 2933000 + cpuinfo_cur_freq : 3196000 + + B) There is a round-off error associated with the cpuinfo_cur_freq value. + Since the driver obtains the current frequency as a "percentage" (%) of the + nominal frequency from the BIOS, sometimes, the values displayed by + scaling_cur_freq and cpuinfo_cur_freq may not match. An example: + + scaling_cur_freq : 1600000 + cpuinfo_cur_freq : 1583000 + + In this example, the nominal frequency is 2933 MHz. The driver obtains the + current frequency, cpuinfo_cur_freq, as 54% of the nominal frequency: + + 54% of 2933 MHz = 1583 MHz + + Nominal frequency is the maximum frequency of the processor, and it usually + corresponds to the frequency of the P0 P-state. + + 2.4 related_cpus: + ----------------- + The related_cpus field is identical to affected_cpus. + + affected_cpus : 4 + related_cpus : 4 + + Currently, the PCC driver does not evaluate _PSD. The platforms that support + PCC do not implement SW_ALL. So OSPM doesn't need to perform any coordination + to ensure that the same frequency is requested of all dependent CPUs. + + 3. Caveats: + ----------- + The "cpufreq_stats" module in its present form cannot be loaded and + expected to work with the PCC driver. Since the "cpufreq_stats" module + provides information wrt each P-state, it is not applicable to the PCC driver. diff --git a/Documentation/admin-guide/pm/working-state.rst b/Documentation/admin-guide/pm/working-state.rst index 88f717e59a42..0a38cdf39df1 100644 --- a/Documentation/admin-guide/pm/working-state.rst +++ b/Documentation/admin-guide/pm/working-state.rst @@ -11,4 +11,5 @@ Working-State Power Management intel_idle cpufreq intel_pstate + cpufreq_drivers intel_epb diff --git a/Documentation/cpu-freq/amd-powernow.txt b/Documentation/cpu-freq/amd-powernow.txt deleted file mode 100644 index 254da155fa47..000000000000 --- a/Documentation/cpu-freq/amd-powernow.txt +++ /dev/null @@ -1,38 +0,0 @@ - -PowerNow! and Cool'n'Quiet are AMD names for frequency -management capabilities in AMD processors. As the hardware -implementation changes in new generations of the processors, -there is a different cpu-freq driver for each generation. - -Note that the driver's will not load on the "wrong" hardware, -so it is safe to try each driver in turn when in doubt as to -which is the correct driver. - -Note that the functionality to change frequency (and voltage) -is not available in all processors. The drivers will refuse -to load on processors without this capability. The capability -is detected with the cpuid instruction. - -The drivers use BIOS supplied tables to obtain frequency and -voltage information appropriate for a particular platform. -Frequency transitions will be unavailable if the BIOS does -not supply these tables. - -6th Generation: powernow-k6 - -7th Generation: powernow-k7: Athlon, Duron, Geode. - -8th Generation: powernow-k8: Athlon, Athlon 64, Opteron, Sempron. -Documentation on this functionality in 8th generation processors -is available in the "BIOS and Kernel Developer's Guide", publication -26094, in chapter 9, available for download from www.amd.com. - -BIOS supplied data, for powernow-k7 and for powernow-k8, may be -from either the PSB table or from ACPI objects. The ACPI support -is only available if the kernel config sets CONFIG_ACPI_PROCESSOR. -The powernow-k8 driver will attempt to use ACPI if so configured, -and fall back to PST if that fails. -The powernow-k7 driver will try to use the PSB support first, and -fall back to ACPI if the PSB support fails. A module parameter, -acpi_force, is provided to force ACPI support to be used instead -of PSB support. diff --git a/Documentation/cpu-freq/cpufreq-nforce2.txt b/Documentation/cpu-freq/cpufreq-nforce2.txt deleted file mode 100644 index babce1315026..000000000000 --- a/Documentation/cpu-freq/cpufreq-nforce2.txt +++ /dev/null @@ -1,19 +0,0 @@ - -The cpufreq-nforce2 driver changes the FSB on nVidia nForce2 platforms. - -This works better than on other platforms, because the FSB of the CPU -can be controlled independently from the PCI/AGP clock. - -The module has two options: - - fid: multiplier * 10 (for example 8.5 = 85) - min_fsb: minimum FSB - -If not set, fid is calculated from the current CPU speed and the FSB. -min_fsb defaults to FSB at boot time - 50 MHz. - -IMPORTANT: The available range is limited downwards! - Also the minimum available FSB can differ, for systems - booting with 200 MHz, 150 should always work. - - diff --git a/Documentation/cpu-freq/pcc-cpufreq.txt b/Documentation/cpu-freq/pcc-cpufreq.txt deleted file mode 100644 index 9e3c3b33514c..000000000000 --- a/Documentation/cpu-freq/pcc-cpufreq.txt +++ /dev/null @@ -1,207 +0,0 @@ -/* - * pcc-cpufreq.txt - PCC interface documentation - * - * Copyright (C) 2009 Red Hat, Matthew Garrett - * Copyright (C) 2009 Hewlett-Packard Development Company, L.P. - * Nagananda Chumbalkar - * - * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - * - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License as published by - * the Free Software Foundation; version 2 of the License. - * - * This program is distributed in the hope that it will be useful, but - * WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or NON - * INFRINGEMENT. See the GNU General Public License for more details. - * - * You should have received a copy of the GNU General Public License along - * with this program; if not, write to the Free Software Foundation, Inc., - * 675 Mass Ave, Cambridge, MA 02139, USA. - * - * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - */ - - - Processor Clocking Control Driver - --------------------------------- - -Contents: ---------- -1. Introduction -1.1 PCC interface -1.1.1 Get Average Frequency -1.1.2 Set Desired Frequency -1.2 Platforms affected -2. Driver and /sys details -2.1 scaling_available_frequencies -2.2 cpuinfo_transition_latency -2.3 cpuinfo_cur_freq -2.4 related_cpus -3. Caveats - -1. Introduction: ----------------- -Processor Clocking Control (PCC) is an interface between the platform -firmware and OSPM. It is a mechanism for coordinating processor -performance (ie: frequency) between the platform firmware and the OS. - -The PCC driver (pcc-cpufreq) allows OSPM to take advantage of the PCC -interface. - -OS utilizes the PCC interface to inform platform firmware what frequency the -OS wants for a logical processor. The platform firmware attempts to achieve -the requested frequency. If the request for the target frequency could not be -satisfied by platform firmware, then it usually means that power budget -conditions are in place, and "power capping" is taking place. - -1.1 PCC interface: ------------------- -The complete PCC specification is available here: -http://www.acpica.org/download/Processor-Clocking-Control-v1p0.pdf - -PCC relies on a shared memory region that provides a channel for communication -between the OS and platform firmware. PCC also implements a "doorbell" that -is used by the OS to inform the platform firmware that a command has been -sent. - -The ACPI PCCH() method is used to discover the location of the PCC shared -memory region. The shared memory region header contains the "command" and -"status" interface. PCCH() also contains details on how to access the platform -doorbell. - -The following commands are supported by the PCC interface: -* Get Average Frequency -* Set Desired Frequency - -The ACPI PCCP() method is implemented for each logical processor and is -used to discover the offsets for the input and output buffers in the shared -memory region. - -When PCC mode is enabled, the platform will not expose processor performance -or throttle states (_PSS, _TSS and related ACPI objects) to OSPM. Therefore, -the native P-state driver (such as acpi-cpufreq for Intel, powernow-k8 for -AMD) will not load. - -However, OSPM remains in control of policy. The governor (eg: "ondemand") -computes the required performance for each processor based on server workload. -The PCC driver fills in the command interface, and the input buffer and -communicates the request to the platform firmware. The platform firmware is -responsible for delivering the requested performance. - -Each PCC command is "global" in scope and can affect all the logical CPUs in -the system. Therefore, PCC is capable of performing "group" updates. With PCC -the OS is capable of getting/setting the frequency of all the logical CPUs in -the system with a single call to the BIOS. - -1.1.1 Get Average Frequency: ----------------------------- -This command is used by the OSPM to query the running frequency of the -processor since the last time this command was completed. The output buffer -indicates the average unhalted frequency of the logical processor expressed as -a percentage of the nominal (ie: maximum) CPU frequency. The output buffer -also signifies if the CPU frequency is limited by a power budget condition. - -1.1.2 Set Desired Frequency: ----------------------------- -This command is used by the OSPM to communicate to the platform firmware the -desired frequency for a logical processor. The output buffer is currently -ignored by OSPM. The next invocation of "Get Average Frequency" will inform -OSPM if the desired frequency was achieved or not. - -1.2 Platforms affected: ------------------------ -The PCC driver will load on any system where the platform firmware: -* supports the PCC interface, and the associated PCCH() and PCCP() methods -* assumes responsibility for managing the hardware clocking controls in order -to deliver the requested processor performance - -Currently, certain HP ProLiant platforms implement the PCC interface. On those -platforms PCC is the "default" choice. - -However, it is possible to disable this interface via a BIOS setting. In -such an instance, as is also the case on platforms where the PCC interface -is not implemented, the PCC driver will fail to load silently. - -2. Driver and /sys details: ---------------------------- -When the driver loads, it merely prints the lowest and the highest CPU -frequencies supported by the platform firmware. - -The PCC driver loads with a message such as: -pcc-cpufreq: (v1.00.00) driver loaded with frequency limits: 1600 MHz, 2933 -MHz - -This means that the OPSM can request the CPU to run at any frequency in -between the limits (1600 MHz, and 2933 MHz) specified in the message. - -Internally, there is no need for the driver to convert the "target" frequency -to a corresponding P-state. - -The VERSION number for the driver will be of the format v.xy.ab. -eg: 1.00.02 - ----- -- - | | - | -- this will increase with bug fixes/enhancements to the driver - |-- this is the version of the PCC specification the driver adheres to - - -The following is a brief discussion on some of the fields exported via the -/sys filesystem and how their values are affected by the PCC driver: - -2.1 scaling_available_frequencies: ----------------------------------- -scaling_available_frequencies is not created in /sys. No intermediate -frequencies need to be listed because the BIOS will try to achieve any -frequency, within limits, requested by the governor. A frequency does not have -to be strictly associated with a P-state. - -2.2 cpuinfo_transition_latency: -------------------------------- -The cpuinfo_transition_latency field is 0. The PCC specification does -not include a field to expose this value currently. - -2.3 cpuinfo_cur_freq: ---------------------- -A) Often cpuinfo_cur_freq will show a value different than what is declared -in the scaling_available_frequencies or scaling_cur_freq, or scaling_max_freq. -This is due to "turbo boost" available on recent Intel processors. If certain -conditions are met the BIOS can achieve a slightly higher speed than requested -by OSPM. An example: - -scaling_cur_freq : 2933000 -cpuinfo_cur_freq : 3196000 - -B) There is a round-off error associated with the cpuinfo_cur_freq value. -Since the driver obtains the current frequency as a "percentage" (%) of the -nominal frequency from the BIOS, sometimes, the values displayed by -scaling_cur_freq and cpuinfo_cur_freq may not match. An example: - -scaling_cur_freq : 1600000 -cpuinfo_cur_freq : 1583000 - -In this example, the nominal frequency is 2933 MHz. The driver obtains the -current frequency, cpuinfo_cur_freq, as 54% of the nominal frequency: - - 54% of 2933 MHz = 1583 MHz - -Nominal frequency is the maximum frequency of the processor, and it usually -corresponds to the frequency of the P0 P-state. - -2.4 related_cpus: ------------------ -The related_cpus field is identical to affected_cpus. - -affected_cpus : 4 -related_cpus : 4 - -Currently, the PCC driver does not evaluate _PSD. The platforms that support -PCC do not implement SW_ALL. So OSPM doesn't need to perform any coordination -to ensure that the same frequency is requested of all dependent CPUs. - -3. Caveats: ------------ -The "cpufreq_stats" module in its present form cannot be loaded and -expected to work with the PCC driver. Since the "cpufreq_stats" module -provides information wrt each P-state, it is not applicable to the PCC driver. -- cgit v1.2.3 From c111566bea7ccd8a05e2c56f1fb3cbb6f4b7b441 Mon Sep 17 00:00:00 2001 From: Sakari Ailus Date: Tue, 25 Feb 2020 11:31:02 +0200 Subject: PM: runtime: Add pm_runtime_get_if_active() pm_runtime_get_if_in_use() bumps up the PM-runtime usage count if it is not equal to zero and the device's PM-runtime status is 'active'. This works for drivers that do not use autoidle, but for those that do, the function returns zero even when the device is active. In order to maintain sane device state while the device is powered on in the hope that it'll be needed, pm_runtime_get_if_active(dev, true) returns a positive value if the device's PM-runtime status is 'active' when it is called, in which case it also increments the device's usage count. If the second argument of pm_runtime_get_if_active() is 'false', the function behaves just like pm_runtime_get_if_in_use(), so redefine the latter as a wrapper around the former. Signed-off-by: Sakari Ailus [ rjw: Changelog ] Signed-off-by: Rafael J. Wysocki --- Documentation/power/runtime_pm.rst | 6 ++++++ drivers/base/power/runtime.c | 36 +++++++++++++++++++++++++++--------- include/linux/pm_runtime.h | 12 +++++++++++- 3 files changed, 44 insertions(+), 10 deletions(-) (limited to 'Documentation') diff --git a/Documentation/power/runtime_pm.rst b/Documentation/power/runtime_pm.rst index ab8406c84254..0553008b6279 100644 --- a/Documentation/power/runtime_pm.rst +++ b/Documentation/power/runtime_pm.rst @@ -382,6 +382,12 @@ drivers/base/power/runtime.c and include/linux/pm_runtime.h: nonzero, increment the counter and return 1; otherwise return 0 without changing the counter + `int pm_runtime_get_if_active(struct device *dev, bool ign_usage_count);` + - return -EINVAL if 'power.disable_depth' is nonzero; otherwise, if the + runtime PM status is RPM_ACTIVE, and either ign_usage_count is true + or the device's usage_count is non-zero, increment the counter and + return 1; otherwise return 0 without changing the counter + `void pm_runtime_put_noidle(struct device *dev);` - decrement the device's usage counter diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c index 16134a69bf6f..99c7da112c95 100644 --- a/drivers/base/power/runtime.c +++ b/drivers/base/power/runtime.c @@ -1087,29 +1087,47 @@ int __pm_runtime_resume(struct device *dev, int rpmflags) EXPORT_SYMBOL_GPL(__pm_runtime_resume); /** - * pm_runtime_get_if_in_use - Conditionally bump up the device's usage counter. + * pm_runtime_get_if_active - Conditionally bump up the device's usage counter. * @dev: Device to handle. * * Return -EINVAL if runtime PM is disabled for the device. * - * If that's not the case and if the device's runtime PM status is RPM_ACTIVE - * and the runtime PM usage counter is nonzero, increment the counter and - * return 1. Otherwise return 0 without changing the counter. + * Otherwise, if the device's runtime PM status is RPM_ACTIVE and either + * ign_usage_count is true or the device's usage_count is non-zero, increment + * the counter and return 1. Otherwise return 0 without changing the counter. + * + * If ign_usage_count is true, the function can be used to prevent suspending + * the device when its runtime PM status is RPM_ACTIVE. + * + * If ign_usage_count is false, the function can be used to prevent suspending + * the device when both its runtime PM status is RPM_ACTIVE and its usage_count + * is non-zero. + * + * The caller is resposible for putting the device's usage count when ther + * return value is greater than zero. */ -int pm_runtime_get_if_in_use(struct device *dev) +int pm_runtime_get_if_active(struct device *dev, bool ign_usage_count) { unsigned long flags; int retval; spin_lock_irqsave(&dev->power.lock, flags); - retval = dev->power.disable_depth > 0 ? -EINVAL : - dev->power.runtime_status == RPM_ACTIVE - && atomic_inc_not_zero(&dev->power.usage_count); + if (dev->power.disable_depth > 0) { + retval = -EINVAL; + } else if (dev->power.runtime_status != RPM_ACTIVE) { + retval = 0; + } else if (ign_usage_count) { + retval = 1; + atomic_inc(&dev->power.usage_count); + } else { + retval = atomic_inc_not_zero(&dev->power.usage_count); + } trace_rpm_usage_rcuidle(dev, 0); spin_unlock_irqrestore(&dev->power.lock, flags); + return retval; } -EXPORT_SYMBOL_GPL(pm_runtime_get_if_in_use); +EXPORT_SYMBOL_GPL(pm_runtime_get_if_active); /** * __pm_runtime_set_status - Set runtime PM status of a device. diff --git a/include/linux/pm_runtime.h b/include/linux/pm_runtime.h index 22af69d237a6..3bdcbce8141a 100644 --- a/include/linux/pm_runtime.h +++ b/include/linux/pm_runtime.h @@ -38,7 +38,7 @@ extern int pm_runtime_force_resume(struct device *dev); extern int __pm_runtime_idle(struct device *dev, int rpmflags); extern int __pm_runtime_suspend(struct device *dev, int rpmflags); extern int __pm_runtime_resume(struct device *dev, int rpmflags); -extern int pm_runtime_get_if_in_use(struct device *dev); +extern int pm_runtime_get_if_active(struct device *dev, bool ign_usage_count); extern int pm_schedule_suspend(struct device *dev, unsigned int delay); extern int __pm_runtime_set_status(struct device *dev, unsigned int status); extern int pm_runtime_barrier(struct device *dev); @@ -60,6 +60,11 @@ extern void pm_runtime_put_suppliers(struct device *dev); extern void pm_runtime_new_link(struct device *dev); extern void pm_runtime_drop_link(struct device *dev); +static inline int pm_runtime_get_if_in_use(struct device *dev) +{ + return pm_runtime_get_if_active(dev, false); +} + static inline void pm_suspend_ignore_children(struct device *dev, bool enable) { dev->power.ignore_children = enable; @@ -143,6 +148,11 @@ static inline int pm_runtime_get_if_in_use(struct device *dev) { return -EINVAL; } +static inline int pm_runtime_get_if_active(struct device *dev, + bool ign_usage_count) +{ + return -EINVAL; +} static inline int __pm_runtime_set_status(struct device *dev, unsigned int status) { return 0; } static inline int pm_runtime_barrier(struct device *dev) { return 0; } -- cgit v1.2.3 From 12bd112bf8e41ad0a5cbf6d71beacca45eb7d10c Mon Sep 17 00:00:00 2001 From: Mauro Carvalho Chehab Date: Tue, 3 Mar 2020 14:52:03 +0100 Subject: docs: cpu-freq: convert index.txt to ReST most of the stuff there can be re-used with ReST format, but we need to add an empty TOC and remove the existing entries, as the following conversion patches will be re-adding them, as they're converted. Signed-off-by: Mauro Carvalho Chehab Signed-off-by: Rafael J. Wysocki --- Documentation/cpu-freq/index.rst | 35 +++++++++++++++++++++++++ Documentation/cpu-freq/index.txt | 56 ---------------------------------------- Documentation/index.rst | 1 + 3 files changed, 36 insertions(+), 56 deletions(-) create mode 100644 Documentation/cpu-freq/index.rst delete mode 100644 Documentation/cpu-freq/index.txt (limited to 'Documentation') diff --git a/Documentation/cpu-freq/index.rst b/Documentation/cpu-freq/index.rst new file mode 100644 index 000000000000..1bff3dfddd23 --- /dev/null +++ b/Documentation/cpu-freq/index.rst @@ -0,0 +1,35 @@ +.. SPDX-License-Identifier: GPL-2.0 + +============================================================================== +Linux CPUFreq - CPU frequency and voltage scaling code in the Linux(TM) kernel +============================================================================== + +Author: Dominik Brodowski + + Clock scaling allows you to change the clock speed of the CPUs on the + fly. This is a nice method to save battery power, because the lower + the clock speed, the less power the CPU consumes. + + +.. toctree:: + :maxdepth: 1 + +Mailing List +------------ +There is a CPU frequency changing CVS commit and general list where +you can report bugs, problems or submit patches. To post a message, +send an email to linux-pm@vger.kernel.org. + +Links +----- +the FTP archives: +* ftp://ftp.linux.org.uk/pub/linux/cpufreq/ + +how to access the CVS repository: +* http://cvs.arm.linux.org.uk/ + +the CPUFreq Mailing list: +* http://vger.kernel.org/vger-lists.html#linux-pm + +Clock and voltage scaling for the SA-1100: +* http://www.lartmaker.nl/projects/scaling diff --git a/Documentation/cpu-freq/index.txt b/Documentation/cpu-freq/index.txt deleted file mode 100644 index c15e75386a05..000000000000 --- a/Documentation/cpu-freq/index.txt +++ /dev/null @@ -1,56 +0,0 @@ - CPU frequency and voltage scaling code in the Linux(TM) kernel - - - L i n u x C P U F r e q - - - - - Dominik Brodowski - - - - Clock scaling allows you to change the clock speed of the CPUs on the - fly. This is a nice method to save battery power, because the lower - the clock speed, the less power the CPU consumes. - - - -Documents in this directory: ----------------------------- - -amd-powernow.txt - AMD powernow driver specific file. - -core.txt - General description of the CPUFreq core and - of CPUFreq notifiers. - -cpu-drivers.txt - How to implement a new cpufreq processor driver. - -cpufreq-nforce2.txt - nVidia nForce2 platform specific file. - -cpufreq-stats.txt - General description of sysfs cpufreq stats. - -index.txt - File index, Mailing list and Links (this document) - -pcc-cpufreq.txt - PCC cpufreq driver specific file. - - -Mailing List ------------- -There is a CPU frequency changing CVS commit and general list where -you can report bugs, problems or submit patches. To post a message, -send an email to linux-pm@vger.kernel.org. - -Links ------ -the FTP archives: -* ftp://ftp.linux.org.uk/pub/linux/cpufreq/ - -how to access the CVS repository: -* http://cvs.arm.linux.org.uk/ - -the CPUFreq Mailing list: -* http://vger.kernel.org/vger-lists.html#linux-pm - -Clock and voltage scaling for the SA-1100: -* http://www.lartmaker.nl/projects/scaling diff --git a/Documentation/index.rst b/Documentation/index.rst index e99d0bd2589d..4cf37ad1cd1d 100644 --- a/Documentation/index.rst +++ b/Documentation/index.rst @@ -99,6 +99,7 @@ needed). accounting/index block/index cdrom/index + cpu-freq/index ide/index fb/index fpga/index -- cgit v1.2.3 From c460f972d3036dbff73897bf7e4b21bdff7d3eaa Mon Sep 17 00:00:00 2001 From: Mauro Carvalho Chehab Date: Tue, 3 Mar 2020 14:52:04 +0100 Subject: docs: cpu-freq: convert core.txt to ReST - Add a SPDX header; - Adjust the document title, based on the original contents of cpu-freq/index.txt; - Use lists where needed; - Comment out the existing text-only index; - use ``foo`` to mark a literal expression with asterisk; - Adjust some title marks; - Add table markups; - Add notes markups; - Some whitespace fixes and new line breaks; - Add it to cpu-freq/index.rst. Signed-off-by: Mauro Carvalho Chehab Signed-off-by: Rafael J. Wysocki --- Documentation/cpu-freq/core.rst | 113 +++++++++++++++++++++++++++++++++++++++ Documentation/cpu-freq/core.txt | 112 -------------------------------------- Documentation/cpu-freq/index.rst | 2 + 3 files changed, 115 insertions(+), 112 deletions(-) create mode 100644 Documentation/cpu-freq/core.rst delete mode 100644 Documentation/cpu-freq/core.txt (limited to 'Documentation') diff --git a/Documentation/cpu-freq/core.rst b/Documentation/cpu-freq/core.rst new file mode 100644 index 000000000000..33cb90bd1d8f --- /dev/null +++ b/Documentation/cpu-freq/core.rst @@ -0,0 +1,113 @@ +.. SPDX-License-Identifier: GPL-2.0 + +============================================================= +General description of the CPUFreq core and CPUFreq notifiers +============================================================= + +Authors: + - Dominik Brodowski + - David Kimdon + - Rafael J. Wysocki + - Viresh Kumar + +.. Contents: + + 1. CPUFreq core and interfaces + 2. CPUFreq notifiers + 3. CPUFreq Table Generation with Operating Performance Point (OPP) + +1. General Information +====================== + +The CPUFreq core code is located in drivers/cpufreq/cpufreq.c. This +cpufreq code offers a standardized interface for the CPUFreq +architecture drivers (those pieces of code that do actual +frequency transitions), as well as to "notifiers". These are device +drivers or other part of the kernel that need to be informed of +policy changes (ex. thermal modules like ACPI) or of all +frequency changes (ex. timing code) or even need to force certain +speed limits (like LCD drivers on ARM architecture). Additionally, the +kernel "constant" loops_per_jiffy is updated on frequency changes +here. + +Reference counting of the cpufreq policies is done by cpufreq_cpu_get +and cpufreq_cpu_put, which make sure that the cpufreq driver is +correctly registered with the core, and will not be unloaded until +cpufreq_put_cpu is called. That also ensures that the respective cpufreq +policy doesn't get freed while being used. + +2. CPUFreq notifiers +==================== + +CPUFreq notifiers conform to the standard kernel notifier interface. +See linux/include/linux/notifier.h for details on notifiers. + +There are two different CPUFreq notifiers - policy notifiers and +transition notifiers. + + +2.1 CPUFreq policy notifiers +---------------------------- + +These are notified when a new policy is created or removed. + +The phase is specified in the second argument to the notifier. The phase is +CPUFREQ_CREATE_POLICY when the policy is first created and it is +CPUFREQ_REMOVE_POLICY when the policy is removed. + +The third argument, a ``void *pointer``, points to a struct cpufreq_policy +consisting of several values, including min, max (the lower and upper +frequencies (in kHz) of the new policy). + + +2.2 CPUFreq transition notifiers +-------------------------------- + +These are notified twice for each online CPU in the policy, when the +CPUfreq driver switches the CPU core frequency and this change has no +any external implications. + +The second argument specifies the phase - CPUFREQ_PRECHANGE or +CPUFREQ_POSTCHANGE. + +The third argument is a struct cpufreq_freqs with the following +values: + +===== =========================== +cpu number of the affected CPU +old old frequency +new new frequency +flags flags of the cpufreq driver +===== =========================== + +3. CPUFreq Table Generation with Operating Performance Point (OPP) +================================================================== +For details about OPP, see Documentation/power/opp.rst + +dev_pm_opp_init_cpufreq_table - + This function provides a ready to use conversion routine to translate + the OPP layer's internal information about the available frequencies + into a format readily providable to cpufreq. + + .. Warning:: + + Do not use this function in interrupt context. + + Example:: + + soc_pm_init() + { + /* Do things */ + r = dev_pm_opp_init_cpufreq_table(dev, &freq_table); + if (!r) + policy->freq_table = freq_table; + /* Do other things */ + } + + .. note:: + + This function is available only if CONFIG_CPU_FREQ is enabled in + addition to CONFIG_PM_OPP. + +dev_pm_opp_free_cpufreq_table + Free up the table allocated by dev_pm_opp_init_cpufreq_table diff --git a/Documentation/cpu-freq/core.txt b/Documentation/cpu-freq/core.txt deleted file mode 100644 index ed577d9c154b..000000000000 --- a/Documentation/cpu-freq/core.txt +++ /dev/null @@ -1,112 +0,0 @@ - CPU frequency and voltage scaling code in the Linux(TM) kernel - - - L i n u x C P U F r e q - - C P U F r e q C o r e - - - Dominik Brodowski - David Kimdon - Rafael J. Wysocki - Viresh Kumar - - - - Clock scaling allows you to change the clock speed of the CPUs on the - fly. This is a nice method to save battery power, because the lower - the clock speed, the less power the CPU consumes. - - -Contents: ---------- -1. CPUFreq core and interfaces -2. CPUFreq notifiers -3. CPUFreq Table Generation with Operating Performance Point (OPP) - -1. General Information -======================= - -The CPUFreq core code is located in drivers/cpufreq/cpufreq.c. This -cpufreq code offers a standardized interface for the CPUFreq -architecture drivers (those pieces of code that do actual -frequency transitions), as well as to "notifiers". These are device -drivers or other part of the kernel that need to be informed of -policy changes (ex. thermal modules like ACPI) or of all -frequency changes (ex. timing code) or even need to force certain -speed limits (like LCD drivers on ARM architecture). Additionally, the -kernel "constant" loops_per_jiffy is updated on frequency changes -here. - -Reference counting of the cpufreq policies is done by cpufreq_cpu_get -and cpufreq_cpu_put, which make sure that the cpufreq driver is -correctly registered with the core, and will not be unloaded until -cpufreq_put_cpu is called. That also ensures that the respective cpufreq -policy doesn't get freed while being used. - -2. CPUFreq notifiers -==================== - -CPUFreq notifiers conform to the standard kernel notifier interface. -See linux/include/linux/notifier.h for details on notifiers. - -There are two different CPUFreq notifiers - policy notifiers and -transition notifiers. - - -2.1 CPUFreq policy notifiers ----------------------------- - -These are notified when a new policy is created or removed. - -The phase is specified in the second argument to the notifier. The phase is -CPUFREQ_CREATE_POLICY when the policy is first created and it is -CPUFREQ_REMOVE_POLICY when the policy is removed. - -The third argument, a void *pointer, points to a struct cpufreq_policy -consisting of several values, including min, max (the lower and upper -frequencies (in kHz) of the new policy). - - -2.2 CPUFreq transition notifiers --------------------------------- - -These are notified twice for each online CPU in the policy, when the -CPUfreq driver switches the CPU core frequency and this change has no -any external implications. - -The second argument specifies the phase - CPUFREQ_PRECHANGE or -CPUFREQ_POSTCHANGE. - -The third argument is a struct cpufreq_freqs with the following -values: -cpu - number of the affected CPU -old - old frequency -new - new frequency -flags - flags of the cpufreq driver - -3. CPUFreq Table Generation with Operating Performance Point (OPP) -================================================================== -For details about OPP, see Documentation/power/opp.rst - -dev_pm_opp_init_cpufreq_table - - This function provides a ready to use conversion routine to translate - the OPP layer's internal information about the available frequencies - into a format readily providable to cpufreq. - - WARNING: Do not use this function in interrupt context. - - Example: - soc_pm_init() - { - /* Do things */ - r = dev_pm_opp_init_cpufreq_table(dev, &freq_table); - if (!r) - policy->freq_table = freq_table; - /* Do other things */ - } - - NOTE: This function is available only if CONFIG_CPU_FREQ is enabled in - addition to CONFIG_PM_OPP. - -dev_pm_opp_free_cpufreq_table - Free up the table allocated by dev_pm_opp_init_cpufreq_table diff --git a/Documentation/cpu-freq/index.rst b/Documentation/cpu-freq/index.rst index 1bff3dfddd23..53501c58f41d 100644 --- a/Documentation/cpu-freq/index.rst +++ b/Documentation/cpu-freq/index.rst @@ -14,6 +14,8 @@ Author: Dominik Brodowski .. toctree:: :maxdepth: 1 + core + Mailing List ------------ There is a CPU frequency changing CVS commit and general list where -- cgit v1.2.3 From 8f92058987a1e3ec851218420ac1ef554aca41fe Mon Sep 17 00:00:00 2001 From: Mauro Carvalho Chehab Date: Tue, 3 Mar 2020 14:52:05 +0100 Subject: docs: cpu-freq: convert cpu-drivers.txt to ReST - Add a SPDX header; - Add a document title, based on the original contents of cpu-freq/index.txt; - Use lists where needed; - Comment out the existing text-only index; - Adjust some title marks; - Add table markups; - Add notes markups; - Mark literal blocks as such; - use ``foo`` for literal texts; - Some whitespace fixes and new line breaks; - Add it to cpu-freq/index.rst. Signed-off-by: Mauro Carvalho Chehab Signed-off-by: Rafael J. Wysocki --- Documentation/cpu-freq/cpu-drivers.rst | 292 ++++++++++++++++++++++++++++++++ Documentation/cpu-freq/cpu-drivers.txt | 295 --------------------------------- Documentation/cpu-freq/index.rst | 1 + 3 files changed, 293 insertions(+), 295 deletions(-) create mode 100644 Documentation/cpu-freq/cpu-drivers.rst delete mode 100644 Documentation/cpu-freq/cpu-drivers.txt (limited to 'Documentation') diff --git a/Documentation/cpu-freq/cpu-drivers.rst b/Documentation/cpu-freq/cpu-drivers.rst new file mode 100644 index 000000000000..a697278ce190 --- /dev/null +++ b/Documentation/cpu-freq/cpu-drivers.rst @@ -0,0 +1,292 @@ +.. SPDX-License-Identifier: GPL-2.0 + +=============================================== +How to Implement a new CPUFreq Processor Driver +=============================================== + +Authors: + + + - Dominik Brodowski + - Rafael J. Wysocki + - Viresh Kumar + +.. Contents + + 1. What To Do? + 1.1 Initialization + 1.2 Per-CPU Initialization + 1.3 verify + 1.4 target/target_index or setpolicy? + 1.5 target/target_index + 1.6 setpolicy + 1.7 get_intermediate and target_intermediate + 2. Frequency Table Helpers + + + +1. What To Do? +============== + +So, you just got a brand-new CPU / chipset with datasheets and want to +add cpufreq support for this CPU / chipset? Great. Here are some hints +on what is necessary: + + +1.1 Initialization +------------------ + +First of all, in an __initcall level 7 (module_init()) or later +function check whether this kernel runs on the right CPU and the right +chipset. If so, register a struct cpufreq_driver with the CPUfreq core +using cpufreq_register_driver() + +What shall this struct cpufreq_driver contain? + + .name - The name of this driver. + + .init - A pointer to the per-policy initialization function. + + .verify - A pointer to a "verification" function. + + .setpolicy _or_ .fast_switch _or_ .target _or_ .target_index - See + below on the differences. + +And optionally + + .flags - Hints for the cpufreq core. + + .driver_data - cpufreq driver specific data. + + .resolve_freq - Returns the most appropriate frequency for a target + frequency. Doesn't change the frequency though. + + .get_intermediate and target_intermediate - Used to switch to stable + frequency while changing CPU frequency. + + .get - Returns current frequency of the CPU. + + .bios_limit - Returns HW/BIOS max frequency limitations for the CPU. + + .exit - A pointer to a per-policy cleanup function called during + CPU_POST_DEAD phase of cpu hotplug process. + + .stop_cpu - A pointer to a per-policy stop function called during + CPU_DOWN_PREPARE phase of cpu hotplug process. + + .suspend - A pointer to a per-policy suspend function which is called + with interrupts disabled and _after_ the governor is stopped for the + policy. + + .resume - A pointer to a per-policy resume function which is called + with interrupts disabled and _before_ the governor is started again. + + .ready - A pointer to a per-policy ready function which is called after + the policy is fully initialized. + + .attr - A pointer to a NULL-terminated list of "struct freq_attr" which + allow to export values to sysfs. + + .boost_enabled - If set, boost frequencies are enabled. + + .set_boost - A pointer to a per-policy function to enable/disable boost + frequencies. + + +1.2 Per-CPU Initialization +-------------------------- + +Whenever a new CPU is registered with the device model, or after the +cpufreq driver registers itself, the per-policy initialization function +cpufreq_driver.init is called if no cpufreq policy existed for the CPU. +Note that the .init() and .exit() routines are called only once for the +policy and not for each CPU managed by the policy. It takes a ``struct +cpufreq_policy *policy`` as argument. What to do now? + +If necessary, activate the CPUfreq support on your CPU. + +Then, the driver must fill in the following values: + ++-----------------------------------+--------------------------------------+ +|policy->cpuinfo.min_freq _and_ | | +|policy->cpuinfo.max_freq | the minimum and maximum frequency | +| | (in kHz) which is supported by | +| | this CPU | ++-----------------------------------+--------------------------------------+ +|policy->cpuinfo.transition_latency | the time it takes on this CPU to | +| | switch between two frequencies in | +| | nanoseconds (if appropriate, else | +| | specify CPUFREQ_ETERNAL) | ++-----------------------------------+--------------------------------------+ +|policy->cur | The current operating frequency of | +| | this CPU (if appropriate) | ++-----------------------------------+--------------------------------------+ +|policy->min, | | +|policy->max, | | +|policy->policy and, if necessary, | | +|policy->governor | must contain the "default policy" for| +| | this CPU. A few moments later, | +| | cpufreq_driver.verify and either | +| | cpufreq_driver.setpolicy or | +| | cpufreq_driver.target/target_index is| +| | called with these values. | ++-----------------------------------+--------------------------------------+ +|policy->cpus | Update this with the masks of the | +| | (online + offline) CPUs that do DVFS | +| | along with this CPU (i.e. that share| +| | clock/voltage rails with it). | ++-----------------------------------+--------------------------------------+ + +For setting some of these values (cpuinfo.min[max]_freq, policy->min[max]), the +frequency table helpers might be helpful. See the section 2 for more information +on them. + + +1.3 verify +---------- + +When the user decides a new policy (consisting of +"policy,governor,min,max") shall be set, this policy must be validated +so that incompatible values can be corrected. For verifying these +values cpufreq_verify_within_limits(``struct cpufreq_policy *policy``, +``unsigned int min_freq``, ``unsigned int max_freq``) function might be helpful. +See section 2 for details on frequency table helpers. + +You need to make sure that at least one valid frequency (or operating +range) is within policy->min and policy->max. If necessary, increase +policy->max first, and only if this is no solution, decrease policy->min. + + +1.4 target or target_index or setpolicy or fast_switch? +------------------------------------------------------- + +Most cpufreq drivers or even most cpu frequency scaling algorithms +only allow the CPU frequency to be set to predefined fixed values. For +these, you use the ->target(), ->target_index() or ->fast_switch() +callbacks. + +Some cpufreq capable processors switch the frequency between certain +limits on their own. These shall use the ->setpolicy() callback. + + +1.5. target/target_index +------------------------ + +The target_index call has two arguments: ``struct cpufreq_policy *policy``, +and ``unsigned int`` index (into the exposed frequency table). + +The CPUfreq driver must set the new frequency when called here. The +actual frequency must be determined by freq_table[index].frequency. + +It should always restore to earlier frequency (i.e. policy->restore_freq) in +case of errors, even if we switched to intermediate frequency earlier. + +Deprecated +---------- +The target call has three arguments: ``struct cpufreq_policy *policy``, +unsigned int target_frequency, unsigned int relation. + +The CPUfreq driver must set the new frequency when called here. The +actual frequency must be determined using the following rules: + +- keep close to "target_freq" +- policy->min <= new_freq <= policy->max (THIS MUST BE VALID!!!) +- if relation==CPUFREQ_REL_L, try to select a new_freq higher than or equal + target_freq. ("L for lowest, but no lower than") +- if relation==CPUFREQ_REL_H, try to select a new_freq lower than or equal + target_freq. ("H for highest, but no higher than") + +Here again the frequency table helper might assist you - see section 2 +for details. + +1.6. fast_switch +---------------- + +This function is used for frequency switching from scheduler's context. +Not all drivers are expected to implement it, as sleeping from within +this callback isn't allowed. This callback must be highly optimized to +do switching as fast as possible. + +This function has two arguments: ``struct cpufreq_policy *policy`` and +``unsigned int target_frequency``. + + +1.7 setpolicy +------------- + +The setpolicy call only takes a ``struct cpufreq_policy *policy`` as +argument. You need to set the lower limit of the in-processor or +in-chipset dynamic frequency switching to policy->min, the upper limit +to policy->max, and -if supported- select a performance-oriented +setting when policy->policy is CPUFREQ_POLICY_PERFORMANCE, and a +powersaving-oriented setting when CPUFREQ_POLICY_POWERSAVE. Also check +the reference implementation in drivers/cpufreq/longrun.c + +1.8 get_intermediate and target_intermediate +-------------------------------------------- + +Only for drivers with target_index() and CPUFREQ_ASYNC_NOTIFICATION unset. + +get_intermediate should return a stable intermediate frequency platform wants to +switch to, and target_intermediate() should set CPU to that frequency, before +jumping to the frequency corresponding to 'index'. Core will take care of +sending notifications and driver doesn't have to handle them in +target_intermediate() or target_index(). + +Drivers can return '0' from get_intermediate() in case they don't wish to switch +to intermediate frequency for some target frequency. In that case core will +directly call ->target_index(). + +NOTE: ->target_index() should restore to policy->restore_freq in case of +failures as core would send notifications for that. + + +2. Frequency Table Helpers +========================== + +As most cpufreq processors only allow for being set to a few specific +frequencies, a "frequency table" with some functions might assist in +some work of the processor driver. Such a "frequency table" consists of +an array of struct cpufreq_frequency_table entries, with driver specific +values in "driver_data", the corresponding frequency in "frequency" and +flags set. At the end of the table, you need to add a +cpufreq_frequency_table entry with frequency set to CPUFREQ_TABLE_END. +And if you want to skip one entry in the table, set the frequency to +CPUFREQ_ENTRY_INVALID. The entries don't need to be in sorted in any +particular order, but if they are cpufreq core will do DVFS a bit +quickly for them as search for best match is faster. + +The cpufreq table is verified automatically by the core if the policy contains a +valid pointer in its policy->freq_table field. + +cpufreq_frequency_table_verify() assures that at least one valid +frequency is within policy->min and policy->max, and all other criteria +are met. This is helpful for the ->verify call. + +cpufreq_frequency_table_target() is the corresponding frequency table +helper for the ->target stage. Just pass the values to this function, +and this function returns the of the frequency table entry which +contains the frequency the CPU shall be set to. + +The following macros can be used as iterators over cpufreq_frequency_table: + +cpufreq_for_each_entry(pos, table) - iterates over all entries of frequency +table. + +cpufreq_for_each_valid_entry(pos, table) - iterates over all entries, +excluding CPUFREQ_ENTRY_INVALID frequencies. +Use arguments "pos" - a ``cpufreq_frequency_table *`` as a loop cursor and +"table" - the ``cpufreq_frequency_table *`` you want to iterate over. + +For example:: + + struct cpufreq_frequency_table *pos, *driver_freq_table; + + cpufreq_for_each_entry(pos, driver_freq_table) { + /* Do something with pos */ + pos->frequency = ... + } + +If you need to work with the position of pos within driver_freq_table, +do not subtract the pointers, as it is quite costly. Instead, use the +macros cpufreq_for_each_entry_idx() and cpufreq_for_each_valid_entry_idx(). diff --git a/Documentation/cpu-freq/cpu-drivers.txt b/Documentation/cpu-freq/cpu-drivers.txt deleted file mode 100644 index 6e353d00cdc6..000000000000 --- a/Documentation/cpu-freq/cpu-drivers.txt +++ /dev/null @@ -1,295 +0,0 @@ - CPU frequency and voltage scaling code in the Linux(TM) kernel - - - L i n u x C P U F r e q - - C P U D r i v e r s - - - information for developers - - - - Dominik Brodowski - Rafael J. Wysocki - Viresh Kumar - - - - Clock scaling allows you to change the clock speed of the CPUs on the - fly. This is a nice method to save battery power, because the lower - the clock speed, the less power the CPU consumes. - - -Contents: ---------- -1. What To Do? -1.1 Initialization -1.2 Per-CPU Initialization -1.3 verify -1.4 target/target_index or setpolicy? -1.5 target/target_index -1.6 setpolicy -1.7 get_intermediate and target_intermediate -2. Frequency Table Helpers - - - -1. What To Do? -============== - -So, you just got a brand-new CPU / chipset with datasheets and want to -add cpufreq support for this CPU / chipset? Great. Here are some hints -on what is necessary: - - -1.1 Initialization ------------------- - -First of all, in an __initcall level 7 (module_init()) or later -function check whether this kernel runs on the right CPU and the right -chipset. If so, register a struct cpufreq_driver with the CPUfreq core -using cpufreq_register_driver() - -What shall this struct cpufreq_driver contain? - - .name - The name of this driver. - - .init - A pointer to the per-policy initialization function. - - .verify - A pointer to a "verification" function. - - .setpolicy _or_ .fast_switch _or_ .target _or_ .target_index - See - below on the differences. - -And optionally - - .flags - Hints for the cpufreq core. - - .driver_data - cpufreq driver specific data. - - .resolve_freq - Returns the most appropriate frequency for a target - frequency. Doesn't change the frequency though. - - .get_intermediate and target_intermediate - Used to switch to stable - frequency while changing CPU frequency. - - .get - Returns current frequency of the CPU. - - .bios_limit - Returns HW/BIOS max frequency limitations for the CPU. - - .exit - A pointer to a per-policy cleanup function called during - CPU_POST_DEAD phase of cpu hotplug process. - - .stop_cpu - A pointer to a per-policy stop function called during - CPU_DOWN_PREPARE phase of cpu hotplug process. - - .suspend - A pointer to a per-policy suspend function which is called - with interrupts disabled and _after_ the governor is stopped for the - policy. - - .resume - A pointer to a per-policy resume function which is called - with interrupts disabled and _before_ the governor is started again. - - .ready - A pointer to a per-policy ready function which is called after - the policy is fully initialized. - - .attr - A pointer to a NULL-terminated list of "struct freq_attr" which - allow to export values to sysfs. - - .boost_enabled - If set, boost frequencies are enabled. - - .set_boost - A pointer to a per-policy function to enable/disable boost - frequencies. - - -1.2 Per-CPU Initialization --------------------------- - -Whenever a new CPU is registered with the device model, or after the -cpufreq driver registers itself, the per-policy initialization function -cpufreq_driver.init is called if no cpufreq policy existed for the CPU. -Note that the .init() and .exit() routines are called only once for the -policy and not for each CPU managed by the policy. It takes a struct -cpufreq_policy *policy as argument. What to do now? - -If necessary, activate the CPUfreq support on your CPU. - -Then, the driver must fill in the following values: - -policy->cpuinfo.min_freq _and_ -policy->cpuinfo.max_freq - the minimum and maximum frequency - (in kHz) which is supported by - this CPU -policy->cpuinfo.transition_latency the time it takes on this CPU to - switch between two frequencies in - nanoseconds (if appropriate, else - specify CPUFREQ_ETERNAL) - -policy->cur The current operating frequency of - this CPU (if appropriate) -policy->min, -policy->max, -policy->policy and, if necessary, -policy->governor must contain the "default policy" for - this CPU. A few moments later, - cpufreq_driver.verify and either - cpufreq_driver.setpolicy or - cpufreq_driver.target/target_index is called - with these values. -policy->cpus Update this with the masks of the - (online + offline) CPUs that do DVFS - along with this CPU (i.e. that share - clock/voltage rails with it). - -For setting some of these values (cpuinfo.min[max]_freq, policy->min[max]), the -frequency table helpers might be helpful. See the section 2 for more information -on them. - - -1.3 verify ----------- - -When the user decides a new policy (consisting of -"policy,governor,min,max") shall be set, this policy must be validated -so that incompatible values can be corrected. For verifying these -values cpufreq_verify_within_limits(struct cpufreq_policy *policy, -unsigned int min_freq, unsigned int max_freq) function might be helpful. -See section 2 for details on frequency table helpers. - -You need to make sure that at least one valid frequency (or operating -range) is within policy->min and policy->max. If necessary, increase -policy->max first, and only if this is no solution, decrease policy->min. - - -1.4 target or target_index or setpolicy or fast_switch? -------------------------------------------------------- - -Most cpufreq drivers or even most cpu frequency scaling algorithms -only allow the CPU frequency to be set to predefined fixed values. For -these, you use the ->target(), ->target_index() or ->fast_switch() -callbacks. - -Some cpufreq capable processors switch the frequency between certain -limits on their own. These shall use the ->setpolicy() callback. - - -1.5. target/target_index ------------------------- - -The target_index call has two arguments: struct cpufreq_policy *policy, -and unsigned int index (into the exposed frequency table). - -The CPUfreq driver must set the new frequency when called here. The -actual frequency must be determined by freq_table[index].frequency. - -It should always restore to earlier frequency (i.e. policy->restore_freq) in -case of errors, even if we switched to intermediate frequency earlier. - -Deprecated: ----------- -The target call has three arguments: struct cpufreq_policy *policy, -unsigned int target_frequency, unsigned int relation. - -The CPUfreq driver must set the new frequency when called here. The -actual frequency must be determined using the following rules: - -- keep close to "target_freq" -- policy->min <= new_freq <= policy->max (THIS MUST BE VALID!!!) -- if relation==CPUFREQ_REL_L, try to select a new_freq higher than or equal - target_freq. ("L for lowest, but no lower than") -- if relation==CPUFREQ_REL_H, try to select a new_freq lower than or equal - target_freq. ("H for highest, but no higher than") - -Here again the frequency table helper might assist you - see section 2 -for details. - -1.6. fast_switch ----------------- - -This function is used for frequency switching from scheduler's context. -Not all drivers are expected to implement it, as sleeping from within -this callback isn't allowed. This callback must be highly optimized to -do switching as fast as possible. - -This function has two arguments: struct cpufreq_policy *policy and -unsigned int target_frequency. - - -1.7 setpolicy -------------- - -The setpolicy call only takes a struct cpufreq_policy *policy as -argument. You need to set the lower limit of the in-processor or -in-chipset dynamic frequency switching to policy->min, the upper limit -to policy->max, and -if supported- select a performance-oriented -setting when policy->policy is CPUFREQ_POLICY_PERFORMANCE, and a -powersaving-oriented setting when CPUFREQ_POLICY_POWERSAVE. Also check -the reference implementation in drivers/cpufreq/longrun.c - -1.8 get_intermediate and target_intermediate --------------------------------------------- - -Only for drivers with target_index() and CPUFREQ_ASYNC_NOTIFICATION unset. - -get_intermediate should return a stable intermediate frequency platform wants to -switch to, and target_intermediate() should set CPU to that frequency, before -jumping to the frequency corresponding to 'index'. Core will take care of -sending notifications and driver doesn't have to handle them in -target_intermediate() or target_index(). - -Drivers can return '0' from get_intermediate() in case they don't wish to switch -to intermediate frequency for some target frequency. In that case core will -directly call ->target_index(). - -NOTE: ->target_index() should restore to policy->restore_freq in case of -failures as core would send notifications for that. - - -2. Frequency Table Helpers -========================== - -As most cpufreq processors only allow for being set to a few specific -frequencies, a "frequency table" with some functions might assist in -some work of the processor driver. Such a "frequency table" consists of -an array of struct cpufreq_frequency_table entries, with driver specific -values in "driver_data", the corresponding frequency in "frequency" and -flags set. At the end of the table, you need to add a -cpufreq_frequency_table entry with frequency set to CPUFREQ_TABLE_END. -And if you want to skip one entry in the table, set the frequency to -CPUFREQ_ENTRY_INVALID. The entries don't need to be in sorted in any -particular order, but if they are cpufreq core will do DVFS a bit -quickly for them as search for best match is faster. - -The cpufreq table is verified automatically by the core if the policy contains a -valid pointer in its policy->freq_table field. - -cpufreq_frequency_table_verify() assures that at least one valid -frequency is within policy->min and policy->max, and all other criteria -are met. This is helpful for the ->verify call. - -cpufreq_frequency_table_target() is the corresponding frequency table -helper for the ->target stage. Just pass the values to this function, -and this function returns the of the frequency table entry which -contains the frequency the CPU shall be set to. - -The following macros can be used as iterators over cpufreq_frequency_table: - -cpufreq_for_each_entry(pos, table) - iterates over all entries of frequency -table. - -cpufreq_for_each_valid_entry(pos, table) - iterates over all entries, -excluding CPUFREQ_ENTRY_INVALID frequencies. -Use arguments "pos" - a cpufreq_frequency_table * as a loop cursor and -"table" - the cpufreq_frequency_table * you want to iterate over. - -For example: - - struct cpufreq_frequency_table *pos, *driver_freq_table; - - cpufreq_for_each_entry(pos, driver_freq_table) { - /* Do something with pos */ - pos->frequency = ... - } - -If you need to work with the position of pos within driver_freq_table, -do not subtract the pointers, as it is quite costly. Instead, use the -macros cpufreq_for_each_entry_idx() and cpufreq_for_each_valid_entry_idx(). diff --git a/Documentation/cpu-freq/index.rst b/Documentation/cpu-freq/index.rst index 53501c58f41d..fcc58b2eee01 100644 --- a/Documentation/cpu-freq/index.rst +++ b/Documentation/cpu-freq/index.rst @@ -15,6 +15,7 @@ Author: Dominik Brodowski :maxdepth: 1 core + cpu-drivers Mailing List ------------ -- cgit v1.2.3 From aadfa206e9bb6fcee0b9fcd2fc39804026cdefcc Mon Sep 17 00:00:00 2001 From: Mauro Carvalho Chehab Date: Tue, 3 Mar 2020 14:52:06 +0100 Subject: docs: cpu-freq: convert cpufreq-stats.txt to ReST - Add a SPDX header; - Add a document title, based on the original contents of cpu-freq/index.txt; - Use lists where needed; - Comment out the existing text-only index; - Adjust some title marks; - Use bold on some places; - Mark literal blocks as such; - Some whitespace fixes and new line breaks; - Add it to cpu-freq/index.rst. Signed-off-by: Mauro Carvalho Chehab Signed-off-by: Rafael J. Wysocki --- Documentation/cpu-freq/cpufreq-stats.rst | 136 +++++++++++++++++++++++++++++++ Documentation/cpu-freq/cpufreq-stats.txt | 127 ----------------------------- Documentation/cpu-freq/index.rst | 1 + 3 files changed, 137 insertions(+), 127 deletions(-) create mode 100644 Documentation/cpu-freq/cpufreq-stats.rst delete mode 100644 Documentation/cpu-freq/cpufreq-stats.txt (limited to 'Documentation') diff --git a/Documentation/cpu-freq/cpufreq-stats.rst b/Documentation/cpu-freq/cpufreq-stats.rst new file mode 100644 index 000000000000..9ad695b1c7db --- /dev/null +++ b/Documentation/cpu-freq/cpufreq-stats.rst @@ -0,0 +1,136 @@ +.. SPDX-License-Identifier: GPL-2.0 + +========================================== +General Description of sysfs CPUFreq Stats +========================================== + +information for users + + +Author: Venkatesh Pallipadi + +.. Contents + + 1. Introduction + 2. Statistics Provided (with example) + 3. Configuring cpufreq-stats + + +1. Introduction +=============== + +cpufreq-stats is a driver that provides CPU frequency statistics for each CPU. +These statistics are provided in /sysfs as a bunch of read_only interfaces. This +interface (when configured) will appear in a separate directory under cpufreq +in /sysfs (/devices/system/cpu/cpuX/cpufreq/stats/) for each CPU. +Various statistics will form read_only files under this directory. + +This driver is designed to be independent of any particular cpufreq_driver +that may be running on your CPU. So, it will work with any cpufreq_driver. + + +2. Statistics Provided (with example) +===================================== + +cpufreq stats provides following statistics (explained in detail below). + +- time_in_state +- total_trans +- trans_table + +All the statistics will be from the time the stats driver has been inserted +(or the time the stats were reset) to the time when a read of a particular +statistic is done. Obviously, stats driver will not have any information +about the frequency transitions before the stats driver insertion. + +:: + + :/sys/devices/system/cpu/cpu0/cpufreq/stats # ls -l + total 0 + drwxr-xr-x 2 root root 0 May 14 16:06 . + drwxr-xr-x 3 root root 0 May 14 15:58 .. + --w------- 1 root root 4096 May 14 16:06 reset + -r--r--r-- 1 root root 4096 May 14 16:06 time_in_state + -r--r--r-- 1 root root 4096 May 14 16:06 total_trans + -r--r--r-- 1 root root 4096 May 14 16:06 trans_table + +- **reset** + +Write-only attribute that can be used to reset the stat counters. This can be +useful for evaluating system behaviour under different governors without the +need for a reboot. + +- **time_in_state** + +This gives the amount of time spent in each of the frequencies supported by +this CPU. The cat output will have "