From mboxrd@z Thu Jan 1 00:00:00 1970 From: Viresh Kumar Subject: Re: [PATCH 1/7] PM / OPP: Introduce a power estimation helper Date: Tue, 29 Jan 2019 10:40:30 +0530 Message-ID: <20190129051030.gu5nhr6vmcd35bzk@vireshk-i7> References: <20190128165522.31749-1-quentin.perret@arm.com> <20190128165522.31749-2-quentin.perret@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20190128165522.31749-2-quentin.perret@arm.com> Sender: linux-kernel-owner@vger.kernel.org To: Quentin Perret Cc: rjw@rjwysocki.net, sudeep.holla@arm.com, liviu.dudau@arm.com, lorenzo.pieralisi@arm.com, robh+dt@kernel.org, mark.rutland@arm.com, nm@ti.com, sboyd@kernel.org, linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, dietmar.eggemann@arm.com, mka@chromium.org List-Id: devicetree@vger.kernel.org On 28-01-19, 16:55, Quentin Perret wrote: > diff --git a/drivers/opp/of.c b/drivers/opp/of.c > index 06f0f632ec47..7572a2eb2fd4 100644 > --- a/drivers/opp/of.c > +++ b/drivers/opp/of.c > @@ -1047,3 +1047,63 @@ 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); > + > +/** > + * of_dev_pm_opp_get_cpu_power() - Estimates the power of a CPU > + * @mW: pointer to the power estimate in milli-watts > + * @KHz: pointer to the OPP's frequency, in kilo-hertz > + * @cpu: CPU for which power needs to be estimated > + * > + * Computes the power estimated by @CPU at the first OPP above @KHz (ceil), > + * and updates @KHz and @mW accordingly. > + * > + * The power is estimated as P = C * V^2 * f, with C the CPU's capacitance > + * (read from the 'dynamic-power-coefficient' devicetree binding) and V and f > + * respectively the voltage and frequency of the OPP. > + * > + * Return: -ENODEV if the CPU device cannot be found, -EINVAL if the power > + * calculation failed because of missing parameters, 0 otherwise. > + */ > +int of_dev_pm_opp_get_cpu_power(unsigned long *mW, unsigned long *KHz, int cpu) I would suggest to change the return type to unsigned long and return 0 for errors and positive values for mW. > +{ > + unsigned long mV, Hz, MHz; MHz is used only once, I think you can get rid of it just open code the division by 1000000. Maybe remove Hz as well and directly use kHz. > + struct device *cpu_dev; > + struct dev_pm_opp *opp; > + struct device_node *np; > + u32 cap; > + u64 tmp; Name this mW with the above changes. > + 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; > + > + MHz = Hz / 1000000; > + tmp = (u64)cap * mV * mV * MHz; > + do_div(tmp, 1000000000); > + > + *mW = (unsigned long)tmp; > + *KHz = Hz / 1000; > + > + return 0; > +} > +EXPORT_SYMBOL_GPL(of_dev_pm_opp_get_cpu_power); > diff --git a/include/linux/pm_opp.h b/include/linux/pm_opp.h > index 0a2a88e5a383..fedde14f5187 100644 > --- a/include/linux/pm_opp.h > +++ b/include/linux/pm_opp.h > @@ -322,6 +322,7 @@ int dev_pm_opp_of_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpuma > struct device_node *dev_pm_opp_of_get_opp_desc_node(struct device *dev); > struct device_node *dev_pm_opp_get_of_node(struct dev_pm_opp *opp); > int of_get_required_opp_performance_state(struct device_node *np, int index); > +int of_dev_pm_opp_get_cpu_power(unsigned long *mW, unsigned long *KHz, int cpu); > #else > static inline int dev_pm_opp_of_add_table(struct device *dev) > { > @@ -364,6 +365,10 @@ static inline int of_get_required_opp_performance_state(struct device_node *np, > { > return -ENOTSUPP; > } Add a blank line here. We missed adding the same before of_get_required_opp_performance_state() earlier, maybe add the new routine before of_get_required_opp_performance_state() and add blank line before and after it :) > +static inline int of_dev_pm_opp_get_cpu_power(unsigned long *mW, unsigned long *KHz, int cpu) > +{ > + return -ENOTSUPP; > +} > #endif > > #endif /* __LINUX_OPP_H__ */ > -- > 2.20.1 -- viresh