target/linux/ipq806x/patches-4.4/169-OPP-Support-adjusting-OPP-voltages-at-runtime.patch

   1 From 111139c943a082364fbbcd9e0cc94cd442481340 Mon Sep 17 00:00:00 2001
   2 From: Stephen Boyd <sboyd@codeaurora.org>
   3 Date: Mon, 1 Jun 2015 18:47:56 -0700
   4 Subject: PM / OPP: Support adjusting OPP voltages at runtime
   5
   6 On some SoCs the Adaptive Voltage Scaling (AVS) technique is
   7 employed to optimize the operating voltage of a device. At a
   8 given frequency, the hardware monitors dynamic factors and either
   9 makes a suggestion for how much to adjust a voltage for the
  10 current frequency, or it automatically adjusts the voltage
  11 without software intervention. Add an API to the OPP library for
  12 the former case, so that AVS type devices can update the voltages
  13 for an OPP when the hardware determines the voltage should
  14 change. The assumption is that drivers like CPUfreq or devfreq
  15 will register for the OPP notifiers and adjust the voltage
  16 according to suggestions that AVS makes.
  17
  18 Cc: Nishanth Menon <nm@ti.com>
  19 Cc: Viresh Kumar <viresh.kumar@linaro.org>
  20 Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
  21 Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
  22 ---
  23  drivers/base/power/opp/core.c | 77 +++++++++++++++++++++++++++++++++++++++++++
  24  include/linux/pm_opp.h        | 10 ++++++
  25  2 files changed, 87 insertions(+)
  26
  27 --- a/drivers/base/power/opp/core.c
  28 +++ b/drivers/base/power/opp/core.c
  29 @@ -1039,6 +1039,83 @@ unlock:
  30  }
  31
  32  /**
  33 + * dev_pm_opp_adjust_voltage() - helper to change the voltage of an opp
  34 + * @dev:               device for which we do this operation
  35 + * @freq:              OPP frequency to adjust voltage of
  36 + * @u_volt:            new OPP voltage
  37 + *
  38 + * Change the voltage of an OPP with an RCU operation.
  39 + *
  40 + * Return: -EINVAL for bad pointers, -ENOMEM if no memory available for the
  41 + * copy operation, returns 0 if no modifcation was done OR modification was
  42 + * successful.
  43 + *
  44 + * Locking: The internal device_opp and opp structures are RCU protected.
  45 + * Hence this function internally uses RCU updater strategy with mutex locks to
  46 + * keep the integrity of the internal data structures. Callers should ensure
  47 + * that this function is *NOT* called under RCU protection or in contexts where
  48 + * mutex locking or synchronize_rcu() blocking calls cannot be used.
  49 + */
  50 +int dev_pm_opp_adjust_voltage(struct device *dev, unsigned long freq,
  51 +                                unsigned long u_volt)
  52 +{
  53 +       struct device_opp *dev_opp;
  54 +       struct dev_pm_opp *new_opp, *tmp_opp, *opp = ERR_PTR(-ENODEV);
  55 +       int r = 0;
  56 +
  57 +       /* keep the node allocated */
  58 +       new_opp = kmalloc(sizeof(*new_opp), GFP_KERNEL);
  59 +       if (!new_opp)
  60 +               return -ENOMEM;
  61 +
  62 +       mutex_lock(&dev_opp_list_lock);
  63 +
  64 +       /* Find the device_opp */
  65 +       dev_opp = _find_device_opp(dev);
  66 +       if (IS_ERR(dev_opp)) {
  67 +               r = PTR_ERR(dev_opp);
  68 +               dev_warn(dev, "%s: Device OPP not found (%d)\n", __func__, r);
  69 +               goto unlock;
  70 +       }
  71 +
  72 +       /* Do we have the frequency? */
  73 +       list_for_each_entry(tmp_opp, &dev_opp->opp_list, node) {
  74 +               if (tmp_opp->rate == freq) {
  75 +                       opp = tmp_opp;
  76 +                       break;
  77 +               }
  78 +       }
  79 +       if (IS_ERR(opp)) {
  80 +               r = PTR_ERR(opp);
  81 +               goto unlock;
  82 +       }
  83 +
  84 +       /* Is update really needed? */
  85 +       if (opp->u_volt == u_volt)
  86 +               goto unlock;
  87 +       /* copy the old data over */
  88 +       *new_opp = *opp;
  89 +
  90 +       /* plug in new node */
  91 +       new_opp->u_volt = u_volt;
  92 +
  93 +       list_replace_rcu(&opp->node, &new_opp->node);
  94 +       mutex_unlock(&dev_opp_list_lock);
  95 +       call_srcu(&dev_opp->srcu_head.srcu, &opp->rcu_head, _kfree_opp_rcu);
  96 +
  97 +       /* Notify the change of the OPP */
  98 +       srcu_notifier_call_chain(&dev_opp->srcu_head, OPP_EVENT_ADJUST_VOLTAGE,
  99 +                                new_opp);
 100 +
 101 +       return 0;
 102 +
 103 +unlock:
 104 +       mutex_unlock(&dev_opp_list_lock);
 105 +       kfree(new_opp);
 106 +       return r;
 107 +}
 108 +
 109 +/**
 110   * dev_pm_opp_enable() - Enable a specific OPP
 111   * @dev:       device for which we do this operation
 112   * @freq:      OPP frequency to enable
 113 --- a/include/linux/pm_opp.h
 114 +++ b/include/linux/pm_opp.h
 115 @@ -22,6 +22,7 @@ struct device;
 116
 117  enum dev_pm_opp_event {
 118         OPP_EVENT_ADD, OPP_EVENT_REMOVE, OPP_EVENT_ENABLE, OPP_EVENT_DISABLE,
 119 +       OPP_EVENT_ADJUST_VOLTAGE,
 120  };
 121
 122  #if defined(CONFIG_PM_OPP)
 123 @@ -50,6 +51,9 @@ int dev_pm_opp_add(struct device *dev, u
 124                    unsigned long u_volt);
 125  void dev_pm_opp_remove(struct device *dev, unsigned long freq);
 126
 127 +int dev_pm_opp_adjust_voltage(struct device *dev, unsigned long freq,
 128 +                  unsigned long u_volt);
 129 +
 130  int dev_pm_opp_enable(struct device *dev, unsigned long freq);
 131
 132  int dev_pm_opp_disable(struct device *dev, unsigned long freq);
 133 @@ -114,6 +118,12 @@ static inline void dev_pm_opp_remove(str
 134  {
 135  }
 136
 137 +static inline int dev_pm_opp_adjust_voltage(struct device *dev,
 138 +               unsigned long freq, unsigned long u_volt)
 139 +{
 140 +       return 0;
 141 +}
 142 +
 143  static inline int dev_pm_opp_enable(struct device *dev, unsigned long freq)
 144  {
 145         return 0;