diff options
Diffstat (limited to 'Documentation/power')
| -rw-r--r-- | Documentation/power/energy-model.rst | 31 |
1 files changed, 16 insertions, 15 deletions
diff --git a/Documentation/power/energy-model.rst b/Documentation/power/energy-model.rst index 8a2788afe89b..7af0e1760962 100644 --- a/Documentation/power/energy-model.rst +++ b/Documentation/power/energy-model.rst @@ -138,6 +138,10 @@ or in Section 2.4 3. Example driver ----------------- +The CPUFreq framework supports dedicated callback for registering +the EM for a given CPU(s) 'policy' object: cpufreq_driver::register_em(). +That callback has to be implemented properly for a given driver, +because the framework would call it at the right time during setup. This section provides a simple example of a CPUFreq driver registering a performance domain in the Energy Model framework using the (fake) 'foo' protocol. The driver implements an est_power() function to be provided to the @@ -167,25 +171,22 @@ EM framework:: 20 return 0; 21 } 22 - 23 static int foo_cpufreq_init(struct cpufreq_policy *policy) + 23 static void foo_cpufreq_register_em(struct cpufreq_policy *policy) 24 { 25 struct em_data_callback em_cb = EM_DATA_CB(est_power); 26 struct device *cpu_dev; - 27 int nr_opp, ret; + 27 int nr_opp; 28 29 cpu_dev = get_cpu_device(cpumask_first(policy->cpus)); 30 - 31 /* Do the actual CPUFreq init work ... */ - 32 ret = do_foo_cpufreq_init(policy); - 33 if (ret) - 34 return ret; - 35 - 36 /* Find the number of OPPs for this policy */ - 37 nr_opp = foo_get_nr_opp(policy); + 31 /* Find the number of OPPs for this policy */ + 32 nr_opp = foo_get_nr_opp(policy); + 33 + 34 /* And register the new performance domain */ + 35 em_dev_register_perf_domain(cpu_dev, nr_opp, &em_cb, policy->cpus, + 36 true); + 37 } 38 - 39 /* And register the new performance domain */ - 40 em_dev_register_perf_domain(cpu_dev, nr_opp, &em_cb, policy->cpus, - 41 true); - 42 - 43 return 0; - 44 } + 39 static struct cpufreq_driver foo_cpufreq_driver = { + 40 .register_em = foo_cpufreq_register_em, + 41 }; |