target/linux/ipq806x/patches-4.4/136-clk-Add-safe-switch-hook.patch

   1 From f7a00ea959be31f9b742042294a359d508edce94 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] 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 Signed-off-by: Ram Chandra Jangir <rjangi@codeaurora.org>
  17 ---
  18  drivers/clk/clk.c            | 61 ++++++++++++++++++++++++++++++++++++++------
  19  include/linux/clk-provider.h |  1 +
  20  2 files changed, 54 insertions(+), 8 deletions(-)
  21
  22 --- a/drivers/clk/clk.c
  23 +++ b/drivers/clk/clk.c
  24 @@ -51,9 +51,12 @@ struct clk_core {
  25         struct clk_core         **parents;
  26         u8                      num_parents;
  27         u8                      new_parent_index;
  28 +       u8                      safe_parent_index;
  29         unsigned long           rate;
  30         unsigned long           req_rate;
  31 +       unsigned long           old_rate;
  32         unsigned long           new_rate;
  33 +       struct clk_core         *safe_parent;
  34         struct clk_core         *new_parent;
  35         struct clk_core         *new_child;
  36         unsigned long           flags;
  37 @@ -1271,7 +1274,8 @@ out:
  38  static void clk_calc_subtree(struct clk_core *core, unsigned long new_rate,
  39                              struct clk_core *new_parent, u8 p_index)
  40  {
  41 -       struct clk_core *child;
  42 +       struct clk_core *child, *parent;
  43 +       struct clk_hw *parent_hw;
  44
  45         core->new_rate = new_rate;
  46         core->new_parent = new_parent;
  47 @@ -1281,6 +1285,18 @@ static void clk_calc_subtree(struct clk_
  48         if (new_parent && new_parent != core->parent)
  49                 new_parent->new_child = core;
  50
  51 +       if (core->ops->get_safe_parent) {
  52 +               parent_hw = core->ops->get_safe_parent(core->hw);
  53 +               if (parent_hw) {
  54 +                       parent = parent_hw->core;
  55 +                       p_index = clk_fetch_parent_index(core, parent);
  56 +                       core->safe_parent_index = p_index;
  57 +                       core->safe_parent = parent;
  58 +               }
  59 +       } else {
  60 +               core->safe_parent = NULL;
  61 +       }
  62 +
  63         hlist_for_each_entry(child, &core->children, child_node) {
  64                 child->new_rate = clk_recalc(child, new_rate);
  65                 clk_calc_subtree(child, child->new_rate, NULL, 0);
  66 @@ -1393,14 +1409,43 @@ static struct clk_core *clk_propagate_ra
  67                                                   unsigned long event)
  68  {
  69         struct clk_core *child, *tmp_clk, *fail_clk = NULL;
  70 +       struct clk_core *old_parent;
  71         int ret = NOTIFY_DONE;
  72
  73 -       if (core->rate == core->new_rate)
  74 +       if (core->rate == core->new_rate && event != POST_RATE_CHANGE)
  75                 return NULL;
  76
  77 +       switch (event) {
  78 +       case PRE_RATE_CHANGE:
  79 +               if (core->safe_parent)
  80 +                       core->ops->set_parent(core->hw, core->safe_parent_index);
  81 +               core->old_rate = core->rate;
  82 +               break;
  83 +       case POST_RATE_CHANGE:
  84 +               if (core->safe_parent) {
  85 +                       old_parent = __clk_set_parent_before(core,
  86 +                                                           core->new_parent);
  87 +                       if (core->ops->set_rate_and_parent) {
  88 +                               core->ops->set_rate_and_parent(core->hw,
  89 +                                               core->new_rate,
  90 +                                               core->new_parent ?
  91 +                                               core->new_parent->rate : 0,
  92 +                                               core->new_parent_index);
  93 +                       } else if (core->ops->set_parent) {
  94 +                               core->ops->set_parent(core->hw,
  95 +                                               core->new_parent_index);
  96 +                       }
  97 +                       __clk_set_parent_after(core, core->new_parent,
  98 +                                               old_parent);
  99 +               }
 100 +               break;
 101 +       }
 102 +
 103         if (core->notifier_count) {
 104 -               ret = __clk_notify(core, event, core->rate, core->new_rate);
 105 -               if (ret & NOTIFY_STOP_MASK)
 106 +               if (event != POST_RATE_CHANGE || core->old_rate != core->rate)
 107 +                       ret = __clk_notify(core, event, core->old_rate,
 108 +                                          core->new_rate);
 109 +               if (ret & NOTIFY_STOP_MASK && event != POST_RATE_CHANGE)
 110                         fail_clk = core;
 111         }
 112
 113 @@ -1446,7 +1491,8 @@ clk_change_rate(struct clk_core *core, u
 114
 115         old_rate = core->rate;
 116
 117 -       if (core->new_parent && core->new_parent != core->parent) {
 118 +       if (core->new_parent && core->new_parent != core->parent &&
 119 +                       !core->safe_parent) {
 120                 old_parent = __clk_set_parent_before(core, core->new_parent);
 121                 trace_clk_set_parent(core, core->new_parent);
 122
 123 @@ -1472,9 +1518,6 @@ clk_change_rate(struct clk_core *core, u
 124
 125         core->rate = core->new_rate;
 126
 127 -       if (core->notifier_count && old_rate != core->rate)
 128 -               __clk_notify(core, POST_RATE_CHANGE, old_rate, core->rate);
 129 -
 130         if (core->flags & CLK_RECALC_NEW_RATES)
 131                 (void)clk_calc_new_rates(core, core->new_rate);
 132
 133 @@ -1537,6 +1580,8 @@ static int clk_core_set_rate_nolock(stru
 134
 135         core->req_rate = req_rate;
 136
 137 +       clk_propagate_rate_change(top, POST_RATE_CHANGE);
 138 +
 139         return ret;
 140  }
 141
 142 --- a/include/linux/clk-provider.h
 143 +++ b/include/linux/clk-provider.h
 144 @@ -202,6 +202,7 @@ struct clk_ops {
 145                                           struct clk_rate_request *req);
 146         int             (*set_parent)(struct clk_hw *hw, u8 index);
 147         u8              (*get_parent)(struct clk_hw *hw);
 148 +       struct clk_hw   *(*get_safe_parent)(struct clk_hw *hw);
 149         int             (*set_rate)(struct clk_hw *hw, unsigned long rate,
 150                                     unsigned long parent_rate);
 151         int             (*set_rate_and_parent)(struct clk_hw *hw,