From 25cb20a212a1f989385dfe23230817e69c62bee5 Mon Sep 17 00:00:00 2001 From: Stephen Boyd Date: Wed, 16 Oct 2019 16:57:53 +0200 Subject: PM / OPP: Support adjusting OPP voltages at runtime 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 derived from [1] submitted by Stephen. [1] https://lore.kernel.org/patchwork/patch/599279/ Signed-off-by: Stephen Boyd [Roger Lu: Changed to rcu less implementation] Signed-off-by: Roger Lu [s.nawrocki@samsung.com: added handling of OPP min/max voltage] Signed-off-by: Sylwester Nawrocki Signed-off-by: Viresh Kumar --- drivers/opp/core.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 69 insertions(+) (limited to 'drivers/opp/core.c') diff --git a/drivers/opp/core.c b/drivers/opp/core.c index 9ff0538ee83a..be7a7d332332 100644 --- a/drivers/opp/core.c +++ b/drivers/opp/core.c @@ -2102,6 +2102,75 @@ put_table: return r; } +/** + * 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 target voltage + * @u_volt_min: new OPP min voltage + * @u_volt_max: new OPP max 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, unsigned long u_volt_min, + unsigned long u_volt_max) + +{ + 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; + opp->supplies->u_volt_min = u_volt_min; + opp->supplies->u_volt_max = u_volt_max; + + 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 -- cgit v1.2.3