sh: clkfwk: refactor rate propagation.

This resyncs the rate propagation strategy with the scheme used by the
OMAP clock framework. Child clocks are tracked on a list under each
parent and propagation happens there specifically rather than constantly
iterating over the global clock list.

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

2 files changed, 79 insertions, 49 deletions

diff --git a/arch/sh/kernel/cpu/clock.c b/arch/sh/kernel/cpu/clock.c
index 17f6c078e85..0a06df8cde2 100644
--- a/arch/sh/kernel/cpu/clock.c
+++ b/arch/sh/kernel/cpu/clock.c
@@ -1,11 +1,11 @@
 /*
  * arch/sh/kernel/cpu/clock.c - SuperH clock framework
  *
- *  Copyright (C) 2005, 2006, 2007  Paul Mundt
+ *  Copyright (C) 2005 - 2009  Paul Mundt
  *
  * This clock framework is derived from the OMAP version by:
  *
- *      Copyright (C) 2004 - 2005 Nokia Corporation
+ *      Copyright (C) 2004 - 2008 Nokia Corporation
  *      Written by Tuukka Tikkanen <tuukka.tikkanen@elektrobit.com>
  *
  *  Modified for omap shared clock framework by Tony Lindgren <tony@atomide.com>
@@ -43,20 +43,20 @@ static DEFINE_MUTEX(clock_list_sem);
  */
 static struct clk master_clk = {
         .name           = "master_clk",
-        .flags          = CLK_ALWAYS_ENABLED | CLK_RATE_PROPAGATES,
+        .flags          = CLK_ALWAYS_ENABLED,
         .rate           = CONFIG_SH_PCLK_FREQ,
 };
 
 static struct clk module_clk = {
         .name           = "module_clk",
         .parent         = &master_clk,
-        .flags          = CLK_ALWAYS_ENABLED | CLK_RATE_PROPAGATES,
+        .flags          = CLK_ALWAYS_ENABLED,
 };
 
 static struct clk bus_clk = {
         .name           = "bus_clk",
         .parent         = &master_clk,
-        .flags          = CLK_ALWAYS_ENABLED | CLK_RATE_PROPAGATES,
+        .flags          = CLK_ALWAYS_ENABLED,
 };
 
 static struct clk cpu_clk = {
@@ -75,27 +75,24 @@ static struct clk *onchip_clocks[] = {
         &cpu_clk,
 };
 
+/* Used for clocks that always have same value as the parent clock */
+unsigned long followparent_recalc(struct clk *clk)
+{
+        return clk->parent->rate;
+}
+
 /* Propagate rate to children */
-static void propagate_rate(struct clk *clk)
+void propagate_rate(struct clk *tclk)
 {
         struct clk *clkp;
 
-        list_for_each_entry(clkp, &clock_list, node) {
-                if (likely(clkp->parent != clk))
-                        continue;
-                if (likely(clkp->ops && clkp->ops->recalc))
+        list_for_each_entry(clkp, &tclk->children, sibling) {
+                if (clkp->ops->recalc)
                         clkp->rate = clkp->ops->recalc(clkp);
-                if (unlikely(clkp->flags & CLK_RATE_PROPAGATES))
-                        propagate_rate(clkp);
+                propagate_rate(clkp);
         }
 }
 
-/* Used for clocks that always have same value as the parent clock */
-unsigned long followparent_recalc(struct clk *clk)
-{
-        return clk->parent->rate;
-}
-
 static void __clk_init(struct clk *clk)
 {
         /*
@@ -180,10 +177,46 @@ void clk_disable(struct clk *clk)
 }
 EXPORT_SYMBOL_GPL(clk_disable);
 
+static LIST_HEAD(root_clks);
+
+/**
+ * recalculate_root_clocks - recalculate and propagate all root clocks
+ *
+ * Recalculates all root clocks (clocks with no parent), which if the
+ * clock's .recalc is set correctly, should also propagate their rates.
+ * Called at init.
+ */
+void recalculate_root_clocks(void)
+{
+        struct clk *clkp;
+
+        list_for_each_entry(clkp, &root_clks, sibling) {
+                if (clkp->ops->recalc)
+                        clkp->rate = clkp->ops->recalc(clkp);
+                propagate_rate(clkp);
+        }
+}
+
 int clk_register(struct clk *clk)
 {
+        if (clk == NULL || IS_ERR(clk))
+                return -EINVAL;
+
+        /*
+         * trap out already registered clocks
+         */
+        if (clk->node.next || clk->node.prev)
+                return 0;
+
         mutex_lock(&clock_list_sem);
 
+        INIT_LIST_HEAD(&clk->children);
+
+        if (clk->parent)
+                list_add(&clk->sibling, &clk->parent->children);
+        else
+                list_add(&clk->sibling, &root_clks);
+
         list_add(&clk->node, &clock_list);
         clk->usecount = 0;
         clk->flags |= CLK_NEEDS_INIT;
@@ -205,6 +238,7 @@ EXPORT_SYMBOL_GPL(clk_register);
 void clk_unregister(struct clk *clk)
 {
         mutex_lock(&clock_list_sem);
+        list_del(&clk->sibling);
         list_del(&clk->node);
         mutex_unlock(&clock_list_sem);
 }
@@ -231,50 +265,53 @@ int clk_set_rate_ex(struct clk *clk, unsigned long rate, int algo_id)
 
                 spin_lock_irqsave(&clock_lock, flags);
                 ret = clk->ops->set_rate(clk, rate, algo_id);
+                if (ret == 0) {
+                        if (clk->ops->recalc)
+                                clk->rate = clk->ops->recalc(clk);
+                        propagate_rate(clk);
+                }
                 spin_unlock_irqrestore(&clock_lock, flags);
         }
 
-        if (unlikely(clk->flags & CLK_RATE_PROPAGATES))
-                propagate_rate(clk);
-
         return ret;
 }
 EXPORT_SYMBOL_GPL(clk_set_rate_ex);
 
 void clk_recalc_rate(struct clk *clk)
 {
-        if (likely(clk->ops && clk->ops->recalc)) {
-                unsigned long flags;
+        unsigned long flags;
 
-                spin_lock_irqsave(&clock_lock, flags);
-                clk->rate = clk->ops->recalc(clk);
-                spin_unlock_irqrestore(&clock_lock, flags);
-        }
+        if (!clk->ops->recalc)
+                return;
 
-        if (unlikely(clk->flags & CLK_RATE_PROPAGATES))
-                propagate_rate(clk);
+        spin_lock_irqsave(&clock_lock, flags);
+        clk->rate = clk->ops->recalc(clk);
+        propagate_rate(clk);
+        spin_unlock_irqrestore(&clock_lock, flags);
 }
 EXPORT_SYMBOL_GPL(clk_recalc_rate);
 
 int clk_set_parent(struct clk *clk, struct clk *parent)
 {
+        unsigned long flags;
         int ret = -EINVAL;
-        struct clk *old;
 
         if (!parent || !clk)
                 return ret;
 
-        old = clk->parent;
-        if (likely(clk->ops && clk->ops->set_parent)) {
-                unsigned long flags;
-                spin_lock_irqsave(&clock_lock, flags);
-                ret = clk->ops->set_parent(clk, parent);
-                spin_unlock_irqrestore(&clock_lock, flags);
-                clk->parent = (ret ? old : parent);
-        }
+        spin_lock_irqsave(&clock_lock, flags);
+        if (clk->usecount == 0) {
+                if (clk->ops->set_parent)
+                        ret = clk->ops->set_parent(clk, parent);
+                if (ret == 0) {
+                        if (clk->ops->recalc)
+                                clk->rate = clk->ops->recalc(clk);
+                        propagate_rate(clk);
+                }
+        } else
+                ret = -EBUSY;
+        spin_unlock_irqrestore(&clock_lock, flags);
 
-        if (unlikely(clk->flags & CLK_RATE_PROPAGATES))
-                propagate_rate(clk);
         return ret;
 }
 EXPORT_SYMBOL_GPL(clk_set_parent);
@@ -457,8 +494,7 @@ int __init clk_init(void)
         ret |= arch_clk_init();
 
         /* Kick the child clocks.. */
-        propagate_rate(&master_clk);
-        propagate_rate(&bus_clk);
+        recalculate_root_clocks();
 
         return ret;
 }
diff --git a/arch/sh/kernel/cpu/sh4a/clock-sh7722.c b/arch/sh/kernel/cpu/sh4a/clock-sh7722.c
index 4bdae84aa6b..8e53829ca07 100644
--- a/arch/sh/kernel/cpu/sh4a/clock-sh7722.c
+++ b/arch/sh/kernel/cpu/sh4a/clock-sh7722.c
@@ -161,9 +161,7 @@ static unsigned long master_clk_recalc(struct clk *clk)
 static void master_clk_init(struct clk *clk)
 {
         clk->parent = NULL;
-        clk->flags |= CLK_RATE_PROPAGATES;
-        clk->rate = CONFIG_SH_PCLK_FREQ;
-        master_clk_recalc(clk);
+        clk->rate = master_clk_recalc(clk);
 }
 
 static unsigned long module_clk_recalc(struct clk *clk)
@@ -541,19 +539,16 @@ static struct clk_ops sh7722_video_clk_ops = {
 static struct clk sh7722_umem_clock = {
         .name = "umem_clk",
         .ops = &sh7722_frqcr_clk_ops,
-        .flags = CLK_RATE_PROPAGATES,
 };
 
 static struct clk sh7722_sh_clock = {
         .name = "sh_clk",
         .ops = &sh7722_frqcr_clk_ops,
-        .flags = CLK_RATE_PROPAGATES,
 };
 
 static struct clk sh7722_peripheral_clock = {
         .name = "peripheral_clk",
         .ops = &sh7722_frqcr_clk_ops,
-        .flags = CLK_RATE_PROPAGATES,
 };
 
 static struct clk sh7722_sdram_clock = {
@@ -564,7 +559,6 @@ static struct clk sh7722_sdram_clock = {
 static struct clk sh7722_r_clock = {
         .name = "r_clk",
         .rate = 32768,
-        .flags = CLK_RATE_PROPAGATES,
 };
 
 #if !defined(CONFIG_CPU_SUBTYPE_SH7343) &&\