On 13/08/2019 15:31, Andrew-sh.Cheng wrote: > From: Stephen Boyd <sboyd@xxxxxxxxxxxxxx> > > On some SoCs the Adaptive Voltage Scaling (AVS) technique is > employed to optimize the operating voltage of a device. At a > given frequency, the hardware monitors dynamic factors and either > makes a suggestion for how much to adjust a voltage for the > current frequency, or it automatically adjusts the voltage > without software intervention. Add an API to the OPP library for > the former case, so that AVS type devices can update the voltages > for an OPP when the hardware determines the voltage should > change. The assumption is that drivers like CPUfreq or devfreq > will register for the OPP notifiers and adjust the voltage > according to suggestions that AVS makes. > > This patch is devired from [1] submitted by Stephen. > [1] https://lore.kernel.org/patchwork/patch/599279/ > > Signed-off-by: Stephen Boyd <sboyd@xxxxxxxxxxxxxx> > Signed-off-by: Roger Lu <roger.lu@xxxxxxxxxxxx> Nit: your signed-off-by tag is missing. Regards, Matthias > --- > drivers/opp/core.c | 63 ++++++++++++++++++++++++++++++++++++++++++++++++++ > include/linux/pm_opp.h | 11 +++++++++ > 2 files changed, 74 insertions(+) > > diff --git a/drivers/opp/core.c b/drivers/opp/core.c > index c094d5d20fd7..407a07f29b12 100644 > --- a/drivers/opp/core.c > +++ b/drivers/opp/core.c > @@ -2054,6 +2054,69 @@ static int _opp_set_availability(struct device *dev, unsigned long freq, > } > > /** > + * dev_pm_opp_adjust_voltage() - helper to change the voltage of an OPP > + * @dev: device for which we do this operation > + * @freq: OPP frequency to adjust voltage of > + * @u_volt: new OPP voltage > + * > + * Return: -EINVAL for bad pointers, -ENOMEM if no memory available for the > + * copy operation, returns 0 if no modifcation was done OR modification was > + * successful. > + */ > +int dev_pm_opp_adjust_voltage(struct device *dev, unsigned long freq, > + unsigned long u_volt) > +{ > + struct opp_table *opp_table; > + struct dev_pm_opp *tmp_opp, *opp = ERR_PTR(-ENODEV); > + int r = 0; > + > + /* Find the opp_table */ > + opp_table = _find_opp_table(dev); > + if (IS_ERR(opp_table)) { > + r = PTR_ERR(opp_table); > + dev_warn(dev, "%s: Device OPP not found (%d)\n", __func__, r); > + return r; > + } > + > + mutex_lock(&opp_table->lock); > + > + /* Do we have the frequency? */ > + list_for_each_entry(tmp_opp, &opp_table->opp_list, node) { > + if (tmp_opp->rate == freq) { > + opp = tmp_opp; > + break; > + } > + } > + > + if (IS_ERR(opp)) { > + r = PTR_ERR(opp); > + goto adjust_unlock; > + } > + > + /* Is update really needed? */ > + if (opp->supplies->u_volt == u_volt) > + goto adjust_unlock; > + > + opp->supplies->u_volt = u_volt; > + > + dev_pm_opp_get(opp); > + mutex_unlock(&opp_table->lock); > + > + /* Notify the voltage change of the OPP */ > + blocking_notifier_call_chain(&opp_table->head, OPP_EVENT_ADJUST_VOLTAGE, > + opp); > + > + dev_pm_opp_put(opp); > + goto adjust_put_table; > + > +adjust_unlock: > + mutex_unlock(&opp_table->lock); > +adjust_put_table: > + dev_pm_opp_put_opp_table(opp_table); > + return r; > +} > + > +/** > * dev_pm_opp_enable() - Enable a specific OPP > * @dev: device for which we do this operation > * @freq: OPP frequency to enable > diff --git a/include/linux/pm_opp.h b/include/linux/pm_opp.h > index af5021f27cb7..86947d53e8c4 100644 > --- a/include/linux/pm_opp.h > +++ b/include/linux/pm_opp.h > @@ -22,6 +22,7 @@ struct opp_table; > > enum dev_pm_opp_event { > OPP_EVENT_ADD, OPP_EVENT_REMOVE, OPP_EVENT_ENABLE, OPP_EVENT_DISABLE, > + OPP_EVENT_ADJUST_VOLTAGE, > }; > > /** > @@ -111,6 +112,9 @@ int dev_pm_opp_add(struct device *dev, unsigned long freq, > void dev_pm_opp_remove(struct device *dev, unsigned long freq); > void dev_pm_opp_remove_all_dynamic(struct device *dev); > > +int dev_pm_opp_adjust_voltage(struct device *dev, unsigned long freq, > + unsigned long u_volt); > + > int dev_pm_opp_enable(struct device *dev, unsigned long freq); > > int dev_pm_opp_disable(struct device *dev, unsigned long freq); > @@ -234,6 +238,13 @@ static inline void dev_pm_opp_remove_all_dynamic(struct device *dev) > { > } > > +static inline int > +dev_pm_opp_adjust_voltage(struct device *dev, unsigned long freq, > + unsigned long u_volt) > +{ > + return 0; > +} > + > static inline int dev_pm_opp_enable(struct device *dev, unsigned long freq) > { > return 0; >
