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 diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
  23 index b94a311..0582068 100644
  24 --- a/drivers/clk/clk.c
  25 +++ b/drivers/clk/clk.c
  26 @@ -1356,6 +1356,7 @@ static void clk_calc_subtree(struct clk *clk, unsigned long new_rate,
  27                              struct clk *new_parent, u8 p_index)
  28  {
  29         struct clk *child;
  30 +       struct clk *parent;
  31
  32         clk->new_rate = new_rate;
  33         clk->new_parent = new_parent;
  34 @@ -1365,6 +1366,17 @@ static void clk_calc_subtree(struct clk *clk, unsigned long new_rate,
  35         if (new_parent && new_parent != clk->parent)
  36                 new_parent->new_child = clk;
  37
  38 +       if (clk->ops->get_safe_parent) {
  39 +               parent = clk->ops->get_safe_parent(clk->hw);
  40 +               if (parent) {
  41 +                       p_index = clk_fetch_parent_index(clk, parent);
  42 +                       clk->safe_parent_index = p_index;
  43 +                       clk->safe_parent = parent;
  44 +               }
  45 +       } else {
  46 +               clk->safe_parent = NULL;
  47 +       }
  48 +
  49         hlist_for_each_entry(child, &clk->children, child_node) {
  50                 if (child->ops->recalc_rate)
  51                         child->new_rate = child->ops->recalc_rate(child->hw, new_rate);
  52 @@ -1450,14 +1462,42 @@ out:
  53  static struct clk *clk_propagate_rate_change(struct clk *clk, unsigned long event)
  54  {
  55         struct clk *child, *tmp_clk, *fail_clk = NULL;
  56 +       struct clk *old_parent;
  57         int ret = NOTIFY_DONE;
  58
  59 -       if (clk->rate == clk->new_rate)
  60 +       if (clk->rate == clk->new_rate && event != POST_RATE_CHANGE)
  61                 return NULL;
  62
  63 +       switch (event) {
  64 +       case PRE_RATE_CHANGE:
  65 +               if (clk->safe_parent)
  66 +                       clk->ops->set_parent(clk->hw, clk->safe_parent_index);
  67 +               break;
  68 +       case POST_RATE_CHANGE:
  69 +               if (clk->safe_parent) {
  70 +                       old_parent = __clk_set_parent_before(clk,
  71 +                                                            clk->new_parent);
  72 +                       if (clk->ops->set_rate_and_parent) {
  73 +                               clk->ops->set_rate_and_parent(clk->hw,
  74 +                                               clk->new_rate,
  75 +                                               clk->new_parent ?
  76 +                                               clk->new_parent->rate : 0,
  77 +                                               clk->new_parent_index);
  78 +                       } else if (clk->ops->set_parent) {
  79 +                               clk->ops->set_parent(clk->hw,
  80 +                                               clk->new_parent_index);
  81 +                       }
  82 +                       __clk_set_parent_after(clk, clk->new_parent,
  83 +                                              old_parent);
  84 +               }
  85 +               break;
  86 +       }
  87 +
  88         if (clk->notifier_count) {
  89 -               ret = __clk_notify(clk, event, clk->rate, clk->new_rate);
  90 -               if (ret & NOTIFY_STOP_MASK)
  91 +               if (event != POST_RATE_CHANGE)
  92 +                       ret = __clk_notify(clk, event, clk->rate,
  93 +                                          clk->new_rate);
  94 +               if (ret & NOTIFY_STOP_MASK && event != POST_RATE_CHANGE)
  95                         fail_clk = clk;
  96         }
  97
  98 @@ -1499,7 +1539,8 @@ static void clk_change_rate(struct clk *clk)
  99         else if (clk->parent)
 100                 best_parent_rate = clk->parent->rate;
 101
 102 -       if (clk->new_parent && clk->new_parent != clk->parent) {
 103 +       if (clk->new_parent && clk->new_parent != clk->parent &&
 104 +                       !clk->safe_parent) {
 105                 old_parent = __clk_set_parent_before(clk, clk->new_parent);
 106
 107                 if (clk->ops->set_rate_and_parent) {
 108 @@ -1522,9 +1563,6 @@ static void clk_change_rate(struct clk *clk)
 109         else
 110                 clk->rate = best_parent_rate;
 111
 112 -       if (clk->notifier_count && old_rate != clk->rate)
 113 -               __clk_notify(clk, POST_RATE_CHANGE, old_rate, clk->rate);
 114 -
 115         hlist_for_each_entry(child, &clk->children, child_node) {
 116                 /* Skip children who will be reparented to another clock */
 117                 if (child->new_parent && child->new_parent != clk)
 118 @@ -1598,6 +1636,7 @@ int clk_set_rate(struct clk *clk, unsigned long rate)
 119         /* change the rates */
 120         clk_change_rate(top);
 121
 122 +       clk_propagate_rate_change(top, POST_RATE_CHANGE);
 123  out:
 124         clk_prepare_unlock();
 125
 126 diff --git a/include/linux/clk-private.h b/include/linux/clk-private.h
 127 index efbf70b..f48684a 100644
 128 --- a/include/linux/clk-private.h
 129 +++ b/include/linux/clk-private.h
 130 @@ -38,8 +38,10 @@ struct clk {
 131         struct clk              **parents;
 132         u8                      num_parents;
 133         u8                      new_parent_index;
 134 +       u8                      safe_parent_index;
 135         unsigned long           rate;
 136         unsigned long           new_rate;
 137 +       struct clk              *safe_parent;
 138         struct clk              *new_parent;
 139         struct clk              *new_child;
 140         unsigned long           flags;
 141 diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
 142 index 939533d..300fcb8 100644
 143 --- a/include/linux/clk-provider.h
 144 +++ b/include/linux/clk-provider.h
 145 @@ -157,6 +157,7 @@ struct clk_ops {
 146                                         struct clk **best_parent_clk);
 147         int             (*set_parent)(struct clk_hw *hw, u8 index);
 148         u8              (*get_parent)(struct clk_hw *hw);
 149 +       struct clk      *(*get_safe_parent)(struct clk_hw *hw);
 150         int             (*set_rate)(struct clk_hw *hw, unsigned long,
 151                                     unsigned long);
 152         int             (*set_rate_and_parent)(struct clk_hw *hw,
 153 --
 154 1.7.10.4
 155