target/linux/ipq806x/patches/0126-clk-Add-safe-switch-hook.patch

   1 From b7b3ceec506179d59e46e3a8ea8b370872cc7fcb Mon Sep 17 00:00:00 2001
   2 From: Stephen Boyd <sboyd@codeaurora.org>
   3 Date: Mon, 31 Mar 2014 16:52:29 -0700
   4 Subject: [PATCH 126/182] 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' that they can switch their parent to while the
  13 upstream source is reprogrammed to support this.
  14
  15 Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
  16 ---
  17  drivers/clk/clk.c            |   53 ++++++++++++++++++++++++++++++++++++------
  18  include/linux/clk-private.h  |    2 ++
  19  include/linux/clk-provider.h |    1 +
  20  3 files changed, 49 insertions(+), 7 deletions(-)
  21
  22 --- a/drivers/clk/clk.c
  23 +++ b/drivers/clk/clk.c
  24 @@ -1356,6 +1356,7 @@ static void clk_calc_subtree(struct clk
  25                              struct clk *new_parent, u8 p_index)
  26  {
  27         struct clk *child;
  28 +       struct clk *parent;
  29
  30         clk->new_rate = new_rate;
  31         clk->new_parent = new_parent;
  32 @@ -1365,6 +1366,17 @@ static void clk_calc_subtree(struct clk
  33         if (new_parent && new_parent != clk->parent)
  34                 new_parent->new_child = clk;
  35
  36 +       if (clk->ops->get_safe_parent) {
  37 +               parent = clk->ops->get_safe_parent(clk->hw);
  38 +               if (parent) {
  39 +                       p_index = clk_fetch_parent_index(clk, parent);
  40 +                       clk->safe_parent_index = p_index;
  41 +                       clk->safe_parent = parent;
  42 +               }
  43 +       } else {
  44 +               clk->safe_parent = NULL;
  45 +       }
  46 +
  47         hlist_for_each_entry(child, &clk->children, child_node) {
  48                 if (child->ops->recalc_rate)
  49                         child->new_rate = child->ops->recalc_rate(child->hw, new_rate);
  50 @@ -1450,14 +1462,42 @@ out:
  51  static struct clk *clk_propagate_rate_change(struct clk *clk, unsigned long event)
  52  {
  53         struct clk *child, *tmp_clk, *fail_clk = NULL;
  54 +       struct clk *old_parent;
  55         int ret = NOTIFY_DONE;
  56
  57 -       if (clk->rate == clk->new_rate)
  58 +       if (clk->rate == clk->new_rate && event != POST_RATE_CHANGE)
  59                 return NULL;
  60
  61 +       switch (event) {
  62 +       case PRE_RATE_CHANGE:
  63 +               if (clk->safe_parent)
  64 +                       clk->ops->set_parent(clk->hw, clk->safe_parent_index);
  65 +               break;
  66 +       case POST_RATE_CHANGE:
  67 +               if (clk->safe_parent) {
  68 +                       old_parent = __clk_set_parent_before(clk,
  69 +                                                            clk->new_parent);
  70 +                       if (clk->ops->set_rate_and_parent) {
  71 +                               clk->ops->set_rate_and_parent(clk->hw,
  72 +                                               clk->new_rate,
  73 +                                               clk->new_parent ?
  74 +                                               clk->new_parent->rate : 0,
  75 +                                               clk->new_parent_index);
  76 +                       } else if (clk->ops->set_parent) {
  77 +                               clk->ops->set_parent(clk->hw,
  78 +                                               clk->new_parent_index);
  79 +                       }
  80 +                       __clk_set_parent_after(clk, clk->new_parent,
  81 +                                              old_parent);
  82 +               }
  83 +               break;
  84 +       }
  85 +
  86         if (clk->notifier_count) {
  87 -               ret = __clk_notify(clk, event, clk->rate, clk->new_rate);
  88 -               if (ret & NOTIFY_STOP_MASK)
  89 +               if (event != POST_RATE_CHANGE)
  90 +                       ret = __clk_notify(clk, event, clk->rate,
  91 +                                          clk->new_rate);
  92 +               if (ret & NOTIFY_STOP_MASK && event != POST_RATE_CHANGE)
  93                         fail_clk = clk;
  94         }
  95
  96 @@ -1499,7 +1539,8 @@ static void clk_change_rate(struct clk *
  97         else if (clk->parent)
  98                 best_parent_rate = clk->parent->rate;
  99
 100 -       if (clk->new_parent && clk->new_parent != clk->parent) {
 101 +       if (clk->new_parent && clk->new_parent != clk->parent &&
 102 +                       !clk->safe_parent) {
 103                 old_parent = __clk_set_parent_before(clk, clk->new_parent);
 104
 105                 if (clk->ops->set_rate_and_parent) {
 106 @@ -1522,9 +1563,6 @@ static void clk_change_rate(struct clk *
 107         else
 108                 clk->rate = best_parent_rate;
 109
 110 -       if (clk->notifier_count && old_rate != clk->rate)
 111 -               __clk_notify(clk, POST_RATE_CHANGE, old_rate, clk->rate);
 112 -
 113         hlist_for_each_entry(child, &clk->children, child_node) {
 114                 /* Skip children who will be reparented to another clock */
 115                 if (child->new_parent && child->new_parent != clk)
 116 @@ -1598,6 +1636,7 @@ int clk_set_rate(struct clk *clk, unsign
 117         /* change the rates */
 118         clk_change_rate(top);
 119
 120 +       clk_propagate_rate_change(top, POST_RATE_CHANGE);
 121  out:
 122         clk_prepare_unlock();
 123
 124 --- a/include/linux/clk-private.h
 125 +++ b/include/linux/clk-private.h
 126 @@ -38,8 +38,10 @@ struct clk {
 127         struct clk              **parents;
 128         u8                      num_parents;
 129         u8                      new_parent_index;
 130 +       u8                      safe_parent_index;
 131         unsigned long           rate;
 132         unsigned long           new_rate;
 133 +       struct clk              *safe_parent;
 134         struct clk              *new_parent;
 135         struct clk              *new_child;
 136         unsigned long           flags;
 137 --- a/include/linux/clk-provider.h
 138 +++ b/include/linux/clk-provider.h
 139 @@ -157,6 +157,7 @@ struct clk_ops {
 140                                         struct clk **best_parent_clk);
 141         int             (*set_parent)(struct clk_hw *hw, u8 index);
 142         u8              (*get_parent)(struct clk_hw *hw);
 143 +       struct clk      *(*get_safe_parent)(struct clk_hw *hw);
 144         int             (*set_rate)(struct clk_hw *hw, unsigned long,
 145                                     unsigned long);
 146         int             (*set_rate_and_parent)(struct clk_hw *hw,