target/linux/ipq806x/patches-4.9/0037-clk-Add-safe-switch-hook.patch

   1 From a1adfb782789ae9b25c928dfe3d639288563a86c Mon Sep 17 00:00:00 2001
   2 From: Stephen Boyd <sboyd@codeaurora.org>
   3 Date: Fri, 20 Mar 2015 23:45:23 -0700
   4 Subject: [PATCH 37/69] clk: Add safe switch hook
   5
   6 Sometimes clocks can't accept their parent source turning off
   7 while the source is reprogrammed to a different rate. Most
   8 notably CPU clocks require a way to switch away from the current
   9 PLL they're running on, reprogram that PLL to a new rate, and
  10 then switch back to the PLL with the new rate once they're done.
  11 Add a hook that drivers can implement allowing them to return a
  12 'safe parent' and 'safe frequency' that they can switch their
  13 parent to while the upstream source is reprogrammed to support
  14 this.
  15
  16 Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
  17 Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>
  18 ---
  19  drivers/clk/clk.c            | 73 +++++++++++++++++++++++++++++++++++++++++---
  20  include/linux/clk-provider.h |  2 ++
  21  2 files changed, 70 insertions(+), 5 deletions(-)
  22
  23 --- a/drivers/clk/clk.c
  24 +++ b/drivers/clk/clk.c
  25 @@ -51,9 +51,13 @@ struct clk_core {
  26         struct clk_core         **parents;
  27         u8                      num_parents;
  28         u8                      new_parent_index;
  29 +       u8                      safe_parent_index;
  30         unsigned long           rate;
  31         unsigned long           req_rate;
  32 +       unsigned long           old_rate;
  33         unsigned long           new_rate;
  34 +       unsigned long           safe_freq;
  35 +       struct clk_core         *safe_parent;
  36         struct clk_core         *new_parent;
  37         struct clk_core         *new_child;
  38         unsigned long           flags;
  39 @@ -1310,7 +1314,9 @@ out:
  40  static void clk_calc_subtree(struct clk_core *core, unsigned long new_rate,
  41                              struct clk_core *new_parent, u8 p_index)
  42  {
  43 -       struct clk_core *child;
  44 +       struct clk_core *child, *parent;
  45 +       struct clk_hw *parent_hw;
  46 +       unsigned long safe_freq = 0;
  47
  48         core->new_rate = new_rate;
  49         core->new_parent = new_parent;
  50 @@ -1320,6 +1326,23 @@ static void clk_calc_subtree(struct clk_
  51         if (new_parent && new_parent != core->parent)
  52                 new_parent->new_child = core;
  53
  54 +       if (core->ops->get_safe_parent) {
  55 +               parent_hw = core->ops->get_safe_parent(core->hw, &safe_freq);
  56 +               if (parent_hw) {
  57 +                       parent = parent_hw->core;
  58 +                       p_index = clk_fetch_parent_index(core, parent);
  59 +                       core->safe_parent_index = p_index;
  60 +                       core->safe_parent = parent;
  61 +                       if (safe_freq)
  62 +                               core->safe_freq = safe_freq;
  63 +                       else
  64 +                               core->safe_freq = 0;
  65 +               }
  66 +       } else {
  67 +               core->safe_parent = NULL;
  68 +               core->safe_freq = 0;
  69 +       }
  70 +
  71         hlist_for_each_entry(child, &core->children, child_node) {
  72                 child->new_rate = clk_recalc(child, new_rate);
  73                 clk_calc_subtree(child, child->new_rate, NULL, 0);
  74 @@ -1432,14 +1455,51 @@ static struct clk_core *clk_propagate_ra
  75                                                   unsigned long event)
  76  {
  77         struct clk_core *child, *tmp_clk, *fail_clk = NULL;
  78 +       struct clk_core *old_parent;
  79         int ret = NOTIFY_DONE;
  80
  81 -       if (core->rate == core->new_rate)
  82 +       if (core->rate == core->new_rate && event != POST_RATE_CHANGE)
  83                 return NULL;
  84
  85 +       switch (event) {
  86 +       case PRE_RATE_CHANGE:
  87 +               if (core->safe_parent) {
  88 +                       if (core->safe_freq)
  89 +                               core->ops->set_rate_and_parent(core->hw,
  90 +                                               core->safe_freq,
  91 +                                               core->safe_parent->rate,
  92 +                                               core->safe_parent_index);
  93 +                       else
  94 +                               core->ops->set_parent(core->hw,
  95 +                                               core->safe_parent_index);
  96 +               }
  97 +               core->old_rate = core->rate;
  98 +               break;
  99 +       case POST_RATE_CHANGE:
 100 +               if (core->safe_parent) {
 101 +                       old_parent = __clk_set_parent_before(core,
 102 +                                                            core->new_parent);
 103 +                       if (core->ops->set_rate_and_parent) {
 104 +                               core->ops->set_rate_and_parent(core->hw,
 105 +                                               core->new_rate,
 106 +                                               core->new_parent ?
 107 +                                               core->new_parent->rate : 0,
 108 +                                               core->new_parent_index);
 109 +                       } else if (core->ops->set_parent) {
 110 +                               core->ops->set_parent(core->hw,
 111 +                                               core->new_parent_index);
 112 +                       }
 113 +                       __clk_set_parent_after(core, core->new_parent,
 114 +                                              old_parent);
 115 +               }
 116 +               break;
 117 +       }
 118 +
 119         if (core->notifier_count) {
 120 -               ret = __clk_notify(core, event, core->rate, core->new_rate);
 121 -               if (ret & NOTIFY_STOP_MASK)
 122 +               if (event != POST_RATE_CHANGE || core->old_rate != core->rate)
 123 +                       ret = __clk_notify(core, event, core->old_rate,
 124 +                                          core->new_rate);
 125 +               if (ret & NOTIFY_STOP_MASK && event != POST_RATE_CHANGE)
 126                         fail_clk = core;
 127         }
 128
 129 @@ -1495,7 +1555,8 @@ clk_change_rate(struct clk_core *core, u
 130                 clk_enable_unlock(flags);
 131         }
 132
 133 -       if (core->new_parent && core->new_parent != core->parent) {
 134 +       if (core->new_parent && core->new_parent != core->parent &&
 135 +           !core->safe_parent) {
 136                 old_parent = __clk_set_parent_before(core, core->new_parent);
 137                 trace_clk_set_parent(core, core->new_parent);
 138
 139 @@ -1601,6 +1662,8 @@ static int clk_core_set_rate_nolock(stru
 140
 141         core->req_rate = req_rate;
 142
 143 +       clk_propagate_rate_change(top, POST_RATE_CHANGE);
 144 +
 145         return 0;
 146  }
 147
 148 --- a/include/linux/clk-provider.h
 149 +++ b/include/linux/clk-provider.h
 150 @@ -206,6 +206,8 @@ struct clk_ops {
 151                                           struct clk_rate_request *req);
 152         int             (*set_parent)(struct clk_hw *hw, u8 index);
 153         u8              (*get_parent)(struct clk_hw *hw);
 154 +       struct clk_hw   *(*get_safe_parent)(struct clk_hw *hw,
 155 +                                           unsigned long *safe_freq);
 156         int             (*set_rate)(struct clk_hw *hw, unsigned long rate,
 157                                     unsigned long parent_rate);
 158         int             (*set_rate_and_parent)(struct clk_hw *hw,