sh: clkfwk: Improve the generic clk_set_parent() implementation.

This causes the generic clk_set_parent() implementation to be a bit more
intelligent. A clk_reparent() is added to move the clock over to the new
parent's sibling list, which then allows the generic rate propagation
code to succeed. This also becomes a nop if the new and old parents are
unchanged.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 20 insertions, 0 deletions

diff --git a/arch/sh/kernel/cpu/clock.c b/arch/sh/kernel/cpu/clock.c
index e027fe5898d6..e3d1de8a46fd 100644
--- a/arch/sh/kernel/cpu/clock.c
+++ b/arch/sh/kernel/cpu/clock.c
@@ -81,6 +81,19 @@ unsigned long followparent_recalc(struct clk *clk)
         return clk->parent->rate;
 }
 
+int clk_reparent(struct clk *child, struct clk *parent)
+{
+        list_del_init(&child->sibling);
+        if (parent)
+                list_add(&child->sibling, &parent->children);
+        child->parent = parent;
+
+        /* now do the debugfs renaming to reattach the child
+           to the proper parent */
+
+        return 0;
+}
+
 /* Propagate rate to children */
 void propagate_rate(struct clk *tclk)
 {
@@ -288,12 +301,19 @@ int clk_set_parent(struct clk *clk, struct clk *parent)
 
         if (!parent || !clk)
                 return ret;
+        if (clk->parent == parent)
+                return 0;
 
         spin_lock_irqsave(&clock_lock, flags);
         if (clk->usecount == 0) {
                 if (clk->ops->set_parent)
                         ret = clk->ops->set_parent(clk, parent);
+                else
+                        ret = clk_reparent(clk, parent);
+
                 if (ret == 0) {
+                        pr_debug("clock: set parent of %s to %s (new rate %ld)\n",
+                                 clk->name, clk->parent->name, clk->rate);
                         if (clk->ops->recalc)
                                 clk->rate = clk->ops->recalc(clk);
                         propagate_rate(clk);