Most of the infrastructure is in place now, with only little left. How to find siblings ?
Stephen Boyd suggested to compare "clocks" properties from CPU's DT node and siblings should match. This patch adds another routine find_siblings() which calls of_clk_shared_by_cpus() to find if CPUs share clock line or not.
If of_clk_shared_by_cpus() returns error, we fallback to all CPUs sharing clock line assumption as existing platforms don't have "clocks" property in all CPU nodes and would fail from of_clk_shared_by_cpus().
Cc: devicetree@vger.kernel.org Signed-off-by: Viresh Kumar viresh.kumar@linaro.org --- .../devicetree/bindings/cpufreq/cpufreq-cpu0.txt | 72 ++++++++++++++++++++-- drivers/cpufreq/cpufreq-cpu0.c | 35 ++++++++++- 2 files changed, 101 insertions(+), 6 deletions(-)
diff --git a/Documentation/devicetree/bindings/cpufreq/cpufreq-cpu0.txt b/Documentation/devicetree/bindings/cpufreq/cpufreq-cpu0.txt index f055515..4b83c1a 100644 --- a/Documentation/devicetree/bindings/cpufreq/cpufreq-cpu0.txt +++ b/Documentation/devicetree/bindings/cpufreq/cpufreq-cpu0.txt @@ -1,11 +1,11 @@ -Generic CPU0 cpufreq driver +Generic cpufreq driver
-It is a generic cpufreq driver for CPU0 frequency management. It +It is a generic cpufreq driver for frequency management. It supports both uniprocessor (UP) and symmetric multiprocessor (SMP) -systems which share clock and voltage across all CPUs. +systems which may or maynot share clock and voltage across all CPUs.
Both required and optional properties listed below must be defined -under node /cpus/cpu@0. +under node /cpus/cpu@x. Where x is the first cpu inside a cluster.
Required properties: - operating-points: Refer to Documentation/devicetree/bindings/power/opp.txt @@ -19,9 +19,16 @@ Optional properties: - cooling-min-level: - cooling-max-level: Please refer to Documentation/devicetree/bindings/thermal/thermal.txt. +- clocks: If CPU clock is populated from DT, "clocks" property must be copied to + every cpu node sharing clock with cpu@x. Generic cpufreq driver compares + "clocks" to find siblings, i.e. to see which CPUs share clock/voltages. If + only cpu@0 contains "clocks" property it is assumed that all CPUs share clock + line.
Examples:
+1. All CPUs share clock/voltages + cpus { #address-cells = <1>; #size-cells = <0>; @@ -36,6 +43,8 @@ cpus { 396000 950000 198000 850000 >; + clocks = <&clock CLK_ARM_CLK>; + clock-names = "cpu"; clock-latency = <61036>; /* two CLK32 periods */ #cooling-cells = <2>; cooling-min-level = <0>; @@ -46,17 +55,72 @@ cpus { compatible = "arm,cortex-a9"; reg = <1>; next-level-cache = <&L2>; + clocks = <&clock CLK_ARM_CLK>; };
cpu@2 { compatible = "arm,cortex-a9"; reg = <2>; next-level-cache = <&L2>; + clocks = <&clock CLK_ARM_CLK>; };
cpu@3 { compatible = "arm,cortex-a9"; reg = <3>; next-level-cache = <&L2>; + clocks = <&clock CLK_ARM_CLK>; + }; +}; + + +2. All CPUs inside a cluster share clock/voltages, there are multiple clusters. + +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 + >; + clocks = <&clock CLK_ARM1_CLK>; + clock-names = "cpu"; + clock-latency = <61036>; /* two CLK32 periods */ + }; + + cpu@1 { + compatible = "arm,cortex-a15"; + reg = <1>; + next-level-cache = <&L2>; + clocks = <&clock CLK_ARM1_CLK>; + }; + + cpu@100 { + compatible = "arm,cortex-a7"; + reg = <100>; + next-level-cache = <&L2>; + operating-points = < + /* kHz uV */ + 792000 950000 + 396000 750000 + 198000 450000 + >; + clocks = <&clock CLK_ARM2_CLK>; + clock-names = "cpu"; + clock-latency = <61036>; /* two CLK32 periods */ + }; + + cpu@101 { + compatible = "arm,cortex-a7"; + reg = <101>; + next-level-cache = <&L2>; + clocks = <&clock CLK_ARM2_CLK>; }; }; diff --git a/drivers/cpufreq/cpufreq-cpu0.c b/drivers/cpufreq/cpufreq-cpu0.c index 44633f6..b3f2bf0 100644 --- a/drivers/cpufreq/cpufreq-cpu0.c +++ b/drivers/cpufreq/cpufreq-cpu0.c @@ -177,6 +177,30 @@ try_again: return ret; }
+/* + * Sets all CPUs as sibling if any cpu doesn't have a "clocks" property, + * Otherwise it matches "clocks" property to find siblings. + */ +static void find_siblings(struct cpufreq_policy *policy) +{ + int cpu, ret; + + for_each_possible_cpu(cpu) { + if (cpu == policy->cpu) + continue; + + ret = of_clk_shared_by_cpus(policy->cpu, cpu); + + /* Error while parsing nodes, fallback to set-all */ + if (ret < 0) { + cpumask_setall(policy->cpus); + return; + } else if (ret == 1) { + cpumask_set_cpu(cpu, policy->cpus); + } + } +} + static int cpu0_cpufreq_init(struct cpufreq_policy *policy) { struct cpufreq_frequency_table *freq_table; @@ -266,9 +290,16 @@ static int cpu0_cpufreq_init(struct cpufreq_policy *policy) policy->driver_data = priv;
policy->clk = cpu_clk; - ret = cpufreq_generic_init(policy, freq_table, transition_latency); - if (ret) + + find_siblings(policy); + ret = cpufreq_table_validate_and_show(policy, freq_table); + if (ret) { + dev_err(cpu_dev, "%s: invalid frequency table: %d\n", __func__, + ret); goto out_cooling_unregister; + } + + policy->cpuinfo.transition_latency = transition_latency;
return 0;