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authorLinus Torvalds2016-12-13 16:39:21 -0800
committerLinus Torvalds2016-12-13 16:39:21 -0800
commitf4000cd99750065d5177555c0a805c97174d1b9f (patch)
tree88ab9f09e8fe1e97f34553f7964ee4598e7a0bfc /Documentation
parent2ec4584eb89b8933d1ee307f2fc9c42e745847d7 (diff)
parent75037120e62b58c536999eb23d70cfcb6d6c0bcc (diff)
Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux
Pull arm64 updates from Catalin Marinas: - struct thread_info moved off-stack (also touching include/linux/thread_info.h and include/linux/restart_block.h) - cpus_have_cap() reworked to avoid __builtin_constant_p() for static key use (also touching drivers/irqchip/irq-gic-v3.c) - uprobes support (currently only for native 64-bit tasks) - Emulation of kernel Privileged Access Never (PAN) using TTBR0_EL1 switching to a reserved page table - CPU capacity information passing via DT or sysfs (used by the scheduler) - support for systems without FP/SIMD (IOW, kernel avoids touching these registers; there is no soft-float ABI, nor kernel emulation for AArch64 FP/SIMD) - handling of hardware watchpoint with unaligned addresses, varied lengths and offsets from base - use of the page table contiguous hint for kernel mappings - hugetlb fixes for sizes involving the contiguous hint - remove unnecessary I-cache invalidation in flush_cache_range() - CNTHCTL_EL2 access fix for CPUs with VHE support (ARMv8.1) - boot-time checks for writable+executable kernel mappings - simplify asm/opcodes.h and avoid including the 32-bit ARM counterpart and make the arm64 kernel headers self-consistent (Xen headers patch merged separately) - Workaround for broken .inst support in certain binutils versions * tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (60 commits) arm64: Disable PAN on uaccess_enable() arm64: Work around broken .inst when defective gas is detected arm64: Add detection code for broken .inst support in binutils arm64: Remove reference to asm/opcodes.h arm64: Get rid of asm/opcodes.h arm64: smp: Prevent raw_smp_processor_id() recursion arm64: head.S: Fix CNTHCTL_EL2 access on VHE system arm64: Remove I-cache invalidation from flush_cache_range() arm64: Enable HIBERNATION in defconfig arm64: Enable CONFIG_ARM64_SW_TTBR0_PAN arm64: xen: Enable user access before a privcmd hvc call arm64: Handle faults caused by inadvertent user access with PAN enabled arm64: Disable TTBR0_EL1 during normal kernel execution arm64: Introduce uaccess_{disable,enable} functionality based on TTBR0_EL1 arm64: Factor out TTBR0_EL1 post-update workaround into a specific asm macro arm64: Factor out PAN enabling/disabling into separate uaccess_* macros arm64: Update the synchronous external abort fault description selftests: arm64: add test for unaligned/inexact watchpoint handling arm64: Allow hw watchpoint of length 3,5,6 and 7 arm64: hw_breakpoint: Handle inexact watchpoint addresses ...
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/devicetree/bindings/arm/cpu-capacity.txt236
-rw-r--r--Documentation/devicetree/bindings/arm/cpus.txt10
2 files changed, 246 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/arm/cpu-capacity.txt b/Documentation/devicetree/bindings/arm/cpu-capacity.txt
new file mode 100644
index 000000000000..7809fbe0cdb7
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/cpu-capacity.txt
@@ -0,0 +1,236 @@
+==========================================
+ARM CPUs capacity bindings
+==========================================
+
+==========================================
+1 - Introduction
+==========================================
+
+ARM systems may be configured to have cpus with different power/performance
+characteristics within the same chip. In this case, additional information has
+to be made available to the kernel for it to be aware of such differences and
+take decisions accordingly.
+
+==========================================
+2 - CPU capacity definition
+==========================================
+
+CPU capacity is a number that provides the scheduler information about CPUs
+heterogeneity. Such heterogeneity can come from micro-architectural differences
+(e.g., ARM big.LITTLE systems) or maximum frequency at which CPUs can run
+(e.g., SMP systems with multiple frequency domains). Heterogeneity in this
+context is about differing performance characteristics; this binding tries to
+capture a first-order approximation of the relative performance of CPUs.
+
+CPU capacities are obtained by running a suitable benchmark. This binding makes
+no guarantees on the validity or suitability of any particular benchmark, the
+final capacity should, however, be:
+
+* A "single-threaded" or CPU affine benchmark
+* Divided by the running frequency of the CPU executing the benchmark
+* Not subject to dynamic frequency scaling of the CPU
+
+For the time being we however advise usage of the Dhrystone benchmark. What
+above thus becomes:
+
+CPU capacities are obtained by running the Dhrystone benchmark on each CPU at
+max frequency (with caches enabled). The obtained DMIPS score is then divided
+by the frequency (in MHz) at which the benchmark has been run, so that
+DMIPS/MHz are obtained. Such values are then normalized w.r.t. the highest
+score obtained in the system.
+
+==========================================
+3 - capacity-dmips-mhz
+==========================================
+
+capacity-dmips-mhz is an optional cpu node [1] property: u32 value
+representing CPU capacity expressed in normalized DMIPS/MHz. At boot time, the
+maximum frequency available to the cpu is then used to calculate the capacity
+value internally used by the kernel.
+
+capacity-dmips-mhz property is all-or-nothing: if it is specified for a cpu
+node, it has to be specified for every other cpu nodes, or the system will
+fall back to the default capacity value for every CPU. If cpufreq is not
+available, final capacities are calculated by directly using capacity-dmips-
+mhz values (normalized w.r.t. the highest value found while parsing the DT).
+
+===========================================
+4 - Examples
+===========================================
+
+Example 1 (ARM 64-bit, 6-cpu system, two clusters):
+capacities-dmips-mhz are scaled w.r.t. 1024 (cpu@0 and cpu@1)
+supposing cluster0@max-freq=1100 and custer1@max-freq=850,
+final capacities are 1024 for cluster0 and 446 for cluster1
+
+cpus {
+ #address-cells = <2>;
+ #size-cells = <0>;
+
+ cpu-map {
+ cluster0 {
+ core0 {
+ cpu = <&A57_0>;
+ };
+ core1 {
+ cpu = <&A57_1>;
+ };
+ };
+
+ cluster1 {
+ core0 {
+ cpu = <&A53_0>;
+ };
+ core1 {
+ cpu = <&A53_1>;
+ };
+ core2 {
+ cpu = <&A53_2>;
+ };
+ core3 {
+ cpu = <&A53_3>;
+ };
+ };
+ };
+
+ idle-states {
+ entry-method = "arm,psci";
+
+ CPU_SLEEP_0: cpu-sleep-0 {
+ compatible = "arm,idle-state";
+ arm,psci-suspend-param = <0x0010000>;
+ local-timer-stop;
+ entry-latency-us = <100>;
+ exit-latency-us = <250>;
+ min-residency-us = <150>;
+ };
+
+ CLUSTER_SLEEP_0: cluster-sleep-0 {
+ compatible = "arm,idle-state";
+ arm,psci-suspend-param = <0x1010000>;
+ local-timer-stop;
+ entry-latency-us = <800>;
+ exit-latency-us = <700>;
+ min-residency-us = <2500>;
+ };
+ };
+
+ A57_0: cpu@0 {
+ compatible = "arm,cortex-a57","arm,armv8";
+ reg = <0x0 0x0>;
+ device_type = "cpu";
+ enable-method = "psci";
+ next-level-cache = <&A57_L2>;
+ clocks = <&scpi_dvfs 0>;
+ cpu-idle-states = <&CPU_SLEEP_0 &CLUSTER_SLEEP_0>;
+ capacity-dmips-mhz = <1024>;
+ };
+
+ A57_1: cpu@1 {
+ compatible = "arm,cortex-a57","arm,armv8";
+ reg = <0x0 0x1>;
+ device_type = "cpu";
+ enable-method = "psci";
+ next-level-cache = <&A57_L2>;
+ clocks = <&scpi_dvfs 0>;
+ cpu-idle-states = <&CPU_SLEEP_0 &CLUSTER_SLEEP_0>;
+ capacity-dmips-mhz = <1024>;
+ };
+
+ A53_0: cpu@100 {
+ compatible = "arm,cortex-a53","arm,armv8";
+ reg = <0x0 0x100>;
+ device_type = "cpu";
+ enable-method = "psci";
+ next-level-cache = <&A53_L2>;
+ clocks = <&scpi_dvfs 1>;
+ cpu-idle-states = <&CPU_SLEEP_0 &CLUSTER_SLEEP_0>;
+ capacity-dmips-mhz = <578>;
+ };
+
+ A53_1: cpu@101 {
+ compatible = "arm,cortex-a53","arm,armv8";
+ reg = <0x0 0x101>;
+ device_type = "cpu";
+ enable-method = "psci";
+ next-level-cache = <&A53_L2>;
+ clocks = <&scpi_dvfs 1>;
+ cpu-idle-states = <&CPU_SLEEP_0 &CLUSTER_SLEEP_0>;
+ capacity-dmips-mhz = <578>;
+ };
+
+ A53_2: cpu@102 {
+ compatible = "arm,cortex-a53","arm,armv8";
+ reg = <0x0 0x102>;
+ device_type = "cpu";
+ enable-method = "psci";
+ next-level-cache = <&A53_L2>;
+ clocks = <&scpi_dvfs 1>;
+ cpu-idle-states = <&CPU_SLEEP_0 &CLUSTER_SLEEP_0>;
+ capacity-dmips-mhz = <578>;
+ };
+
+ A53_3: cpu@103 {
+ compatible = "arm,cortex-a53","arm,armv8";
+ reg = <0x0 0x103>;
+ device_type = "cpu";
+ enable-method = "psci";
+ next-level-cache = <&A53_L2>;
+ clocks = <&scpi_dvfs 1>;
+ cpu-idle-states = <&CPU_SLEEP_0 &CLUSTER_SLEEP_0>;
+ capacity-dmips-mhz = <578>;
+ };
+
+ A57_L2: l2-cache0 {
+ compatible = "cache";
+ };
+
+ A53_L2: l2-cache1 {
+ compatible = "cache";
+ };
+};
+
+Example 2 (ARM 32-bit, 4-cpu system, two clusters,
+ cpus 0,1@1GHz, cpus 2,3@500MHz):
+capacities-dmips-mhz are scaled w.r.t. 2 (cpu@0 and cpu@1), this means that first
+cpu@0 and cpu@1 are twice fast than cpu@2 and cpu@3 (at the same frequency)
+
+cpus {
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ cpu0: cpu@0 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a15";
+ reg = <0>;
+ capacity-dmips-mhz = <2>;
+ };
+
+ cpu1: cpu@1 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a15";
+ reg = <1>;
+ capacity-dmips-mhz = <2>;
+ };
+
+ cpu2: cpu@2 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a15";
+ reg = <0x100>;
+ capacity-dmips-mhz = <1>;
+ };
+
+ cpu3: cpu@3 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a15";
+ reg = <0x101>;
+ capacity-dmips-mhz = <1>;
+ };
+};
+
+===========================================
+5 - References
+===========================================
+
+[1] ARM Linux Kernel documentation - CPUs bindings
+ Documentation/devicetree/bindings/arm/cpus.txt
diff --git a/Documentation/devicetree/bindings/arm/cpus.txt b/Documentation/devicetree/bindings/arm/cpus.txt
index e6782d50cbcd..c1dcf4cade2e 100644
--- a/Documentation/devicetree/bindings/arm/cpus.txt
+++ b/Documentation/devicetree/bindings/arm/cpus.txt
@@ -241,6 +241,14 @@ nodes to be present and contain the properties described below.
# List of phandles to idle state nodes supported
by this cpu [3].
+ - capacity-dmips-mhz
+ Usage: Optional
+ Value type: <u32>
+ Definition:
+ # u32 value representing CPU capacity [3] in
+ DMIPS/MHz, relative to highest capacity-dmips-mhz
+ in the system.
+
- rockchip,pmu
Usage: optional for systems that have an "enable-method"
property value of "rockchip,rk3066-smp"
@@ -464,3 +472,5 @@ cpus {
[2] arm/msm/qcom,kpss-acc.txt
[3] ARM Linux kernel documentation - idle states bindings
Documentation/devicetree/bindings/arm/idle-states.txt
+[3] ARM Linux kernel documentation - cpu capacity bindings
+ Documentation/devicetree/bindings/arm/cpu-capacity.txt