diff options
author | Viresh Kumar <viresh.kumar@linaro.org> | 2013-04-01 12:57:49 +0000 |
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committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2013-04-02 15:26:32 +0200 |
commit | 8a67f0ef2b684b34162d39e8f436fe39e9635a19 (patch) | |
tree | dc997ac3064c69e775485213b824e7c3efeb5b99 /Documentation/devicetree/bindings/cpufreq | |
parent | eb2f50ff93f08c8001d0d7e1148948ba80989aaf (diff) | |
download | linux-8a67f0ef2b684b34162d39e8f436fe39e9635a19.tar.bz2 |
cpufreq: ARM big LITTLE: Add generic cpufreq driver and its DT glue
big LITTLE is ARM's new Architecture focussing power/performance needs of modern
world. More information about big LITTLE can be found here:
http://www.arm.com/products/processors/technologies/biglittleprocessing.php
http://lwn.net/Articles/481055/
In order to keep cpufreq support for all big LITTLE platforms simple/generic,
this patch tries to add a generic cpufreq driver layer for all big LITTLE
platforms.
The driver is divided into two parts:
- Core driver: Generic and shared across all big LITTLE SoC's
- Glue drivers: Per platform drivers providing ops to the core driver
This patch adds in a generic glue driver which would extract information from
Device Tree.
Future SoC's can either reuse the DT glue or write their own depending on the
need.
Signed-off-by: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'Documentation/devicetree/bindings/cpufreq')
-rw-r--r-- | Documentation/devicetree/bindings/cpufreq/arm_big_little_dt.txt | 65 |
1 files changed, 65 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/cpufreq/arm_big_little_dt.txt b/Documentation/devicetree/bindings/cpufreq/arm_big_little_dt.txt new file mode 100644 index 000000000000..0715695e94a9 --- /dev/null +++ b/Documentation/devicetree/bindings/cpufreq/arm_big_little_dt.txt @@ -0,0 +1,65 @@ +Generic ARM big LITTLE cpufreq driver's DT glue +----------------------------------------------- + +This is DT specific glue layer for generic cpufreq driver for big LITTLE +systems. + +Both required and optional properties listed below must be defined +under node /cpus/cpu@x. Where x is the first cpu inside a cluster. + +FIXME: Cpus should boot in the order specified in DT and all cpus for a cluster +must be present contiguously. Generic DT driver will check only node 'x' for +cpu:x. + +Required properties: +- operating-points: Refer to Documentation/devicetree/bindings/power/opp.txt + for details + +Optional properties: +- clock-latency: Specify the possible maximum transition latency for clock, + in unit of nanoseconds. + +Examples: + +cpus { + #address-cells = <1>; + #size-cells = <0>; + + cpu@0 { + compatible = "arm,cortex-a15"; + reg = <0>; + next-level-cache = <&L2>; + operating-points = < + /* kHz uV */ + 792000 1100000 + 396000 950000 + 198000 850000 + >; + clock-latency = <61036>; /* two CLK32 periods */ + }; + + cpu@1 { + compatible = "arm,cortex-a15"; + reg = <1>; + next-level-cache = <&L2>; + }; + + cpu@100 { + compatible = "arm,cortex-a7"; + reg = <100>; + next-level-cache = <&L2>; + operating-points = < + /* kHz uV */ + 792000 950000 + 396000 750000 + 198000 450000 + >; + clock-latency = <61036>; /* two CLK32 periods */ + }; + + cpu@101 { + compatible = "arm,cortex-a7"; + reg = <101>; + next-level-cache = <&L2>; + }; +}; |