diff options
Diffstat (limited to 'drivers/opp/of.c')
| -rw-r--r-- | drivers/opp/of.c | 99 |
1 files changed, 99 insertions, 0 deletions
diff --git a/drivers/opp/of.c b/drivers/opp/of.c index 1779f2c93291..62504b18f198 100644 --- a/drivers/opp/of.c +++ b/drivers/opp/of.c @@ -20,6 +20,7 @@ #include <linux/pm_domain.h> #include <linux/slab.h> #include <linux/export.h> +#include <linux/energy_model.h> #include "opp.h" @@ -1049,3 +1050,101 @@ struct device_node *dev_pm_opp_get_of_node(struct dev_pm_opp *opp) return of_node_get(opp->np); } EXPORT_SYMBOL_GPL(dev_pm_opp_get_of_node); + +/* + * Callback function provided to the Energy Model framework upon registration. + * This computes the power estimated by @CPU at @kHz if it is the frequency + * of an existing OPP, or at the frequency of the first OPP above @kHz otherwise + * (see dev_pm_opp_find_freq_ceil()). This function updates @kHz to the ceiled + * frequency and @mW to the associated power. The power is estimated as + * P = C * V^2 * f with C being the CPU's capacitance and V and f respectively + * the voltage and frequency of the OPP. + * + * Returns -ENODEV if the CPU device cannot be found, -EINVAL if the power + * calculation failed because of missing parameters, 0 otherwise. + */ +static int __maybe_unused _get_cpu_power(unsigned long *mW, unsigned long *kHz, + int cpu) +{ + struct device *cpu_dev; + struct dev_pm_opp *opp; + struct device_node *np; + unsigned long mV, Hz; + u32 cap; + u64 tmp; + int ret; + + cpu_dev = get_cpu_device(cpu); + if (!cpu_dev) + return -ENODEV; + + np = of_node_get(cpu_dev->of_node); + if (!np) + return -EINVAL; + + ret = of_property_read_u32(np, "dynamic-power-coefficient", &cap); + of_node_put(np); + if (ret) + return -EINVAL; + + Hz = *kHz * 1000; + opp = dev_pm_opp_find_freq_ceil(cpu_dev, &Hz); + if (IS_ERR(opp)) + return -EINVAL; + + mV = dev_pm_opp_get_voltage(opp) / 1000; + dev_pm_opp_put(opp); + if (!mV) + return -EINVAL; + + tmp = (u64)cap * mV * mV * (Hz / 1000000); + do_div(tmp, 1000000000); + + *mW = (unsigned long)tmp; + *kHz = Hz / 1000; + + return 0; +} + +/** + * dev_pm_opp_of_register_em() - Attempt to register an Energy Model + * @cpus : CPUs for which an Energy Model has to be registered + * + * This checks whether the "dynamic-power-coefficient" devicetree property has + * been specified, and tries to register an Energy Model with it if it has. + */ +void dev_pm_opp_of_register_em(struct cpumask *cpus) +{ + struct em_data_callback em_cb = EM_DATA_CB(_get_cpu_power); + int ret, nr_opp, cpu = cpumask_first(cpus); + struct device *cpu_dev; + struct device_node *np; + u32 cap; + + cpu_dev = get_cpu_device(cpu); + if (!cpu_dev) + return; + + nr_opp = dev_pm_opp_get_opp_count(cpu_dev); + if (nr_opp <= 0) + return; + + np = of_node_get(cpu_dev->of_node); + if (!np) + return; + + /* + * Register an EM only if the 'dynamic-power-coefficient' property is + * set in devicetree. It is assumed the voltage values are known if that + * property is set since it is useless otherwise. If voltages are not + * known, just let the EM registration fail with an error to alert the + * user about the inconsistent configuration. + */ + ret = of_property_read_u32(np, "dynamic-power-coefficient", &cap); + of_node_put(np); + if (ret || !cap) + return; + + em_register_perf_domain(cpus, nr_opp, &em_cb); +} +EXPORT_SYMBOL_GPL(dev_pm_opp_of_register_em); |