| Message ID | 1373247868-21444-3-git-send-email-mturquette@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 07/07/2013 08:44 PM, Mike Turquette wrote: > This patch builds on "clk: notifier handler for dynamic voltage scaling" > by adding a CPUfreq-specific helper function for registering a clock > rate-change notifier to scale regulator voltage as a function of clock > rate. > > In particular this patch creates an instance of struct > cpufreq_frequency_table and also calculate the voltage scaling latency, > both of which are returned to the caller for use in the CPUfreq driver. > > Signed-off-by: Mike Turquette <mturquette@linaro.org> > --- > drivers/clk/clk-voltage-notifier.c | 71 ++++++++++++++++++++++++++++++++++++++ > include/linux/clk.h | 6 ++++ > 2 files changed, 77 insertions(+) As stage 1 of the transition, I dont have any complaints, but for SoC level, at least on OMAP, it is not just regulator and clock, we have additional tweaks to do - like ABB, AVS etc. What would you suggest as the strategy to introduce SoC specific handlers for voltage notifiers that can co-exist with this? > > diff --git a/drivers/clk/clk-voltage-notifier.c b/drivers/clk/clk-voltage-notifier.c > index cb6b85f..8e1707f 100644 > --- a/drivers/clk/clk-voltage-notifier.c > +++ b/drivers/clk/clk-voltage-notifier.c > @@ -10,6 +10,7 @@ > */ > > #include <linux/clk.h> > +#include <linux/cpufreq.h> for example - we should not depend on cpufreq in a generic clock based dvfs approach. we would like to allow devfreq also to transition to this. > #include <linux/device.h> > #include <linux/module.h> > #include <linux/notifier.h> > @@ -133,3 +134,73 @@ void of_clk_volt_notifier_unregister(struct notifier_block *nb) > kfree(vsd); > } > EXPORT_SYMBOL_GPL(of_clk_volt_notifier_unregister); > + > +void of_clk_cpufreq_notifier_unregister(struct notifier_block *nb, > + struct cpufreq_frequency_table *freq_table) > +{ > + struct volt_scale_data *data = to_volt_scale_data(nb); > + struct device *dev = data->dev; > + > + opp_free_cpufreq_table(dev, &freq_table); > + of_clk_volt_notifier_unregister(nb); > +} > +EXPORT_SYMBOL_GPL(of_clk_cpufreq_notifier_unregister); > + > +/** > + * of_clk_cpufreq_notifer_register - register clock notifier to scale voltage > + * @dev: device that owns this scaling operation > + * @np: pointer to device's DT node > + * @clk: clock whose rate-change notifier triggers voltage scaling > + * @supply: regulator id string > + * @freq_table: pointer to uninitialized CPUfreq frequency scaling table > + * @voltage_latency: worst case voltage scaling latency > + */ > +struct notifier_block *of_clk_cpufreq_notifier_register(struct device *dev, > + struct device_node *np, struct clk *clk, const char *supply, > + struct cpufreq_frequency_table **table, > + unsigned int *voltage_latency) > +{ > + struct notifier_block *nb; > + struct volt_scale_data *vsd; > + struct opp *opp; > + unsigned long min, max; > + int ret, i; > + > + nb = of_clk_volt_notifier_register(dev, np, clk, supply, > + voltage_latency); > + if (IS_ERR(nb)) > + return nb; > + > + vsd = to_volt_scale_data(nb); > + > + ret = opp_init_cpufreq_table(dev, table); > + if (ret) { > + pr_err("failed to init cpufreq table: %d\n", ret); > + goto err_unregister; > + } > + > + /* find the min and max voltages and compute worst-case latency */ > + for (i = 0; table[0][i].frequency != CPUFREQ_TABLE_END; i++) > + ; > + > + rcu_read_lock(); > + opp = opp_find_freq_exact(dev, > + table[0][0].frequency * 1000, true); > + min = opp_get_voltage(opp); > + opp = opp_find_freq_exact(dev, > + table[0][i-1].frequency * 1000, true); > + max = opp_get_voltage(opp); > + rcu_read_unlock(); > + > + *voltage_latency = regulator_set_voltage_time(vsd->reg, min, max); > + if (*voltage_latency < 0) > + pr_warn("%s: failed to calculate voltage latency, %d\n", > + __func__, ret); > + > + return nb; > + > +err_unregister: > + of_clk_volt_notifier_unregister(nb); > + return ERR_PTR(ret); > +} > +EXPORT_SYMBOL_GPL(of_clk_cpufreq_notifier_register); > diff --git a/include/linux/clk.h b/include/linux/clk.h > index 85ea520..3104883 100644 > --- a/include/linux/clk.h > +++ b/include/linux/clk.h > @@ -86,6 +86,12 @@ struct notifier_block *of_clk_volt_notifier_register(struct device *dev, > struct device_node *np, struct clk *clk, const char *supply, > int *voltage_latency); > void of_clk_volt_notifier_unregister(struct notifier_block *nb); > +struct notifier_block *of_clk_cpufreq_notifier_register(struct device *dev, > + struct device_node *np, struct clk *clk, const char *supply, > + struct cpufreq_frequency_table **table, > + unsigned int *voltage_latency); > +void of_clk_cpufreq_notifier_unregister(struct notifier_block *nb, > + struct cpufreq_frequency_table *freq_table); > > #endif > >
Quoting Nishanth Menon (2013-07-31 07:36:57) > On 07/07/2013 08:44 PM, Mike Turquette wrote: > > This patch builds on "clk: notifier handler for dynamic voltage scaling" > > by adding a CPUfreq-specific helper function for registering a clock > > rate-change notifier to scale regulator voltage as a function of clock > > rate. > > > > In particular this patch creates an instance of struct > > cpufreq_frequency_table and also calculate the voltage scaling latency, > > both of which are returned to the caller for use in the CPUfreq driver. > > > > Signed-off-by: Mike Turquette <mturquette@linaro.org> > > --- > > drivers/clk/clk-voltage-notifier.c | 71 ++++++++++++++++++++++++++++++++++++++ > > include/linux/clk.h | 6 ++++ > > 2 files changed, 77 insertions(+) > > As stage 1 of the transition, I dont have any complaints, but for SoC > level, at least on OMAP, it is not just regulator and clock, we have > additional tweaks to do - like ABB, AVS etc. > > What would you suggest as the strategy to introduce SoC specific > handlers for voltage notifiers that can co-exist with this? I would suggest to use the clock rate-change notifier handlers. Every version of these "helper" functions that I have posted are simply that: helper functions. There is nothing stopping you today from using the rate-change notifiers that were merged back in v3.4 and scaling multiple regulators in a specific order. This patch is solving the simple case of one clock, one regulator. You may construct your own notifier handler as needed and I have said this many times in the past. I would also point out that if a DT binding existed to properly express operating points as tuples of clock/clock-rate and support for multiple regulator/voltage pairs then I would have implemented that in this patch. As it stands the OPP library today doesn't go into that complexity nor does the operating-points DT binding. This patch chooses the path of least resistance. > > > > > diff --git a/drivers/clk/clk-voltage-notifier.c b/drivers/clk/clk-voltage-notifier.c > > index cb6b85f..8e1707f 100644 > > --- a/drivers/clk/clk-voltage-notifier.c > > +++ b/drivers/clk/clk-voltage-notifier.c > > @@ -10,6 +10,7 @@ > > */ > > > > #include <linux/clk.h> > > +#include <linux/cpufreq.h> > > for example - we should not depend on cpufreq in a generic clock based > dvfs approach. we would like to allow devfreq also to transition to this. See patch #1 in this series. Patch #2 builds on patch #1 to handle the very common case of CPUfreq. It is purely a helper and the goal is to reduce the duplicated boilerplate that would go into every CPUfreq driver if this patch did not exist. I would also like to see devfreq drivers use this mechanism and they can do exactly that with the stuff made available in patch #1. There is clearly no dependency on CPUfreq for you to scale voltage from a clock rate-change notifier. Regards, Mike > > > #include <linux/device.h> > > #include <linux/module.h> > > #include <linux/notifier.h> > > @@ -133,3 +134,73 @@ void of_clk_volt_notifier_unregister(struct notifier_block *nb) > > kfree(vsd); > > } > > EXPORT_SYMBOL_GPL(of_clk_volt_notifier_unregister); > > + > > +void of_clk_cpufreq_notifier_unregister(struct notifier_block *nb, > > + struct cpufreq_frequency_table *freq_table) > > +{ > > + struct volt_scale_data *data = to_volt_scale_data(nb); > > + struct device *dev = data->dev; > > + > > + opp_free_cpufreq_table(dev, &freq_table); > > + of_clk_volt_notifier_unregister(nb); > > +} > > +EXPORT_SYMBOL_GPL(of_clk_cpufreq_notifier_unregister); > > + > > +/** > > + * of_clk_cpufreq_notifer_register - register clock notifier to scale voltage > > + * @dev: device that owns this scaling operation > > + * @np: pointer to device's DT node > > + * @clk: clock whose rate-change notifier triggers voltage scaling > > + * @supply: regulator id string > > + * @freq_table: pointer to uninitialized CPUfreq frequency scaling table > > + * @voltage_latency: worst case voltage scaling latency > > + */ > > +struct notifier_block *of_clk_cpufreq_notifier_register(struct device *dev, > > + struct device_node *np, struct clk *clk, const char *supply, > > + struct cpufreq_frequency_table **table, > > + unsigned int *voltage_latency) > > +{ > > + struct notifier_block *nb; > > + struct volt_scale_data *vsd; > > + struct opp *opp; > > + unsigned long min, max; > > + int ret, i; > > + > > + nb = of_clk_volt_notifier_register(dev, np, clk, supply, > > + voltage_latency); > > + if (IS_ERR(nb)) > > + return nb; > > + > > + vsd = to_volt_scale_data(nb); > > + > > + ret = opp_init_cpufreq_table(dev, table); > > + if (ret) { > > + pr_err("failed to init cpufreq table: %d\n", ret); > > + goto err_unregister; > > + } > > + > > + /* find the min and max voltages and compute worst-case latency */ > > + for (i = 0; table[0][i].frequency != CPUFREQ_TABLE_END; i++) > > + ; > > + > > + rcu_read_lock(); > > + opp = opp_find_freq_exact(dev, > > + table[0][0].frequency * 1000, true); > > + min = opp_get_voltage(opp); > > + opp = opp_find_freq_exact(dev, > > + table[0][i-1].frequency * 1000, true); > > + max = opp_get_voltage(opp); > > + rcu_read_unlock(); > > + > > + *voltage_latency = regulator_set_voltage_time(vsd->reg, min, max); > > + if (*voltage_latency < 0) > > + pr_warn("%s: failed to calculate voltage latency, %d\n", > > + __func__, ret); > > + > > + return nb; > > + > > +err_unregister: > > + of_clk_volt_notifier_unregister(nb); > > + return ERR_PTR(ret); > > +} > > +EXPORT_SYMBOL_GPL(of_clk_cpufreq_notifier_register); > > diff --git a/include/linux/clk.h b/include/linux/clk.h > > index 85ea520..3104883 100644 > > --- a/include/linux/clk.h > > +++ b/include/linux/clk.h > > @@ -86,6 +86,12 @@ struct notifier_block *of_clk_volt_notifier_register(struct device *dev, > > struct device_node *np, struct clk *clk, const char *supply, > > int *voltage_latency); > > void of_clk_volt_notifier_unregister(struct notifier_block *nb); > > +struct notifier_block *of_clk_cpufreq_notifier_register(struct device *dev, > > + struct device_node *np, struct clk *clk, const char *supply, > > + struct cpufreq_frequency_table **table, > > + unsigned int *voltage_latency); > > +void of_clk_cpufreq_notifier_unregister(struct notifier_block *nb, > > + struct cpufreq_frequency_table *freq_table); > > > > #endif > > > > > > > -- > Regards, > Nishanth Menon
diff --git a/drivers/clk/clk-voltage-notifier.c b/drivers/clk/clk-voltage-notifier.c index cb6b85f..8e1707f 100644 --- a/drivers/clk/clk-voltage-notifier.c +++ b/drivers/clk/clk-voltage-notifier.c @@ -10,6 +10,7 @@ */ #include <linux/clk.h> +#include <linux/cpufreq.h> #include <linux/device.h> #include <linux/module.h> #include <linux/notifier.h> @@ -133,3 +134,73 @@ void of_clk_volt_notifier_unregister(struct notifier_block *nb) kfree(vsd); } EXPORT_SYMBOL_GPL(of_clk_volt_notifier_unregister); + +void of_clk_cpufreq_notifier_unregister(struct notifier_block *nb, + struct cpufreq_frequency_table *freq_table) +{ + struct volt_scale_data *data = to_volt_scale_data(nb); + struct device *dev = data->dev; + + opp_free_cpufreq_table(dev, &freq_table); + of_clk_volt_notifier_unregister(nb); +} +EXPORT_SYMBOL_GPL(of_clk_cpufreq_notifier_unregister); + +/** + * of_clk_cpufreq_notifer_register - register clock notifier to scale voltage + * @dev: device that owns this scaling operation + * @np: pointer to device's DT node + * @clk: clock whose rate-change notifier triggers voltage scaling + * @supply: regulator id string + * @freq_table: pointer to uninitialized CPUfreq frequency scaling table + * @voltage_latency: worst case voltage scaling latency + */ +struct notifier_block *of_clk_cpufreq_notifier_register(struct device *dev, + struct device_node *np, struct clk *clk, const char *supply, + struct cpufreq_frequency_table **table, + unsigned int *voltage_latency) +{ + struct notifier_block *nb; + struct volt_scale_data *vsd; + struct opp *opp; + unsigned long min, max; + int ret, i; + + nb = of_clk_volt_notifier_register(dev, np, clk, supply, + voltage_latency); + if (IS_ERR(nb)) + return nb; + + vsd = to_volt_scale_data(nb); + + ret = opp_init_cpufreq_table(dev, table); + if (ret) { + pr_err("failed to init cpufreq table: %d\n", ret); + goto err_unregister; + } + + /* find the min and max voltages and compute worst-case latency */ + for (i = 0; table[0][i].frequency != CPUFREQ_TABLE_END; i++) + ; + + rcu_read_lock(); + opp = opp_find_freq_exact(dev, + table[0][0].frequency * 1000, true); + min = opp_get_voltage(opp); + opp = opp_find_freq_exact(dev, + table[0][i-1].frequency * 1000, true); + max = opp_get_voltage(opp); + rcu_read_unlock(); + + *voltage_latency = regulator_set_voltage_time(vsd->reg, min, max); + if (*voltage_latency < 0) + pr_warn("%s: failed to calculate voltage latency, %d\n", + __func__, ret); + + return nb; + +err_unregister: + of_clk_volt_notifier_unregister(nb); + return ERR_PTR(ret); +} +EXPORT_SYMBOL_GPL(of_clk_cpufreq_notifier_register); diff --git a/include/linux/clk.h b/include/linux/clk.h index 85ea520..3104883 100644 --- a/include/linux/clk.h +++ b/include/linux/clk.h @@ -86,6 +86,12 @@ struct notifier_block *of_clk_volt_notifier_register(struct device *dev, struct device_node *np, struct clk *clk, const char *supply, int *voltage_latency); void of_clk_volt_notifier_unregister(struct notifier_block *nb); +struct notifier_block *of_clk_cpufreq_notifier_register(struct device *dev, + struct device_node *np, struct clk *clk, const char *supply, + struct cpufreq_frequency_table **table, + unsigned int *voltage_latency); +void of_clk_cpufreq_notifier_unregister(struct notifier_block *nb, + struct cpufreq_frequency_table *freq_table); #endif
This patch builds on "clk: notifier handler for dynamic voltage scaling" by adding a CPUfreq-specific helper function for registering a clock rate-change notifier to scale regulator voltage as a function of clock rate. In particular this patch creates an instance of struct cpufreq_frequency_table and also calculate the voltage scaling latency, both of which are returned to the caller for use in the CPUfreq driver. Signed-off-by: Mike Turquette <mturquette@linaro.org> --- drivers/clk/clk-voltage-notifier.c | 71 ++++++++++++++++++++++++++++++++++++++ include/linux/clk.h | 6 ++++ 2 files changed, 77 insertions(+)