[PATCH] sh: clock framework update, fix count and kill off kref

[PATCH] sh: clock framework update, fix count and kill off kref

[Magnus Damm]

From: Magnus Damm <damm@igel.co.jp>

This patch updates the clock framework use count code.
With this patch the enable() and disable() callbacks
only get called when counting from and to zero.
While at it the kref stuff gets replaced with an int.

Signed-off-by: Magnus Damm <damm@igel.co.jp>
---

 arch/sh/include/asm/clock.h |    4 +-
 arch/sh/kernel/cpu/clock.c  |   69 +++++++++++++++++++++++--------------------
 2 files changed, 39 insertions(+), 34 deletions(-)

--- 0001/arch/sh/include/asm/clock.h
+++ work/arch/sh/include/asm/clock.h	2009-05-08 15:36:21.000000000 +0900
@@ -1,7 +1,6 @@
 #ifndef __ASM_SH_CLOCK_H
 #define __ASM_SH_CLOCK_H
 
-#include <linux/kref.h>
 #include <linux/list.h>
 #include <linux/seq_file.h>
 #include <linux/clk.h>
@@ -28,7 +27,7 @@ struct clk {
 	struct clk		*parent;
 	struct clk_ops		*ops;
 
-	struct kref		kref;
+	int			usecount;
 
 	unsigned long		rate;
 	unsigned long		flags;
@@ -37,6 +36,7 @@ struct clk {
 
 #define CLK_ALWAYS_ENABLED	(1 << 0)
 #define CLK_RATE_PROPAGATES	(1 << 1)
+#define CLK_NEEDS_INIT		(1 << 2)
 
 /* Should be defined by processor-specific code */
 void arch_init_clk_ops(struct clk_ops **, int type);
--- 0003/arch/sh/kernel/cpu/clock.c
+++ work/arch/sh/kernel/cpu/clock.c	2009-05-08 15:36:21.000000000 +0900
@@ -19,7 +19,6 @@
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/list.h>
-#include <linux/kref.h>
 #include <linux/kobject.h>
 #include <linux/sysdev.h>
 #include <linux/seq_file.h>
@@ -90,7 +89,7 @@ static void propagate_rate(struct clk *c
 	}
 }
 
-static int __clk_enable(struct clk *clk)
+static void __clk_init(struct clk *clk)
 {
 	/*
 	 * See if this is the first time we're enabling the clock, some
@@ -100,19 +99,33 @@ static int __clk_enable(struct clk *clk)
 	 * divisors to use before it can effectively recalc.
 	 */
 
-	if (clk->flags & CLK_ALWAYS_ENABLED) {
-		kref_get(&clk->kref);
-		return 0;
-	}
-
-	if (unlikely(atomic_read(&clk->kref.refcount) = 1))
+	if (clk->flags & CLK_NEEDS_INIT) {
 		if (clk->ops && clk->ops->init)
 			clk->ops->init(clk);
 
-	kref_get(&clk->kref);
+		clk->flags &= ~CLK_NEEDS_INIT;
+	}
+}
+
+static int __clk_enable(struct clk *clk)
+{
+	if (!clk)
+		return -EINVAL;
+
+	clk->usecount++;
+
+	/* nothing to do if always enabled */
+	if (clk->flags & CLK_ALWAYS_ENABLED)
+		return 0;
+
+	if (clk->usecount = 1) {
+		__clk_init(clk);
 
-	if (likely(clk->ops && clk->ops->enable))
-		clk->ops->enable(clk);
+		__clk_enable(clk->parent);
+
+		if (clk->ops && clk->ops->enable)
+			clk->ops->enable(clk);
+	}
 
 	return 0;
 }
@@ -122,11 +135,6 @@ int clk_enable(struct clk *clk)
 	unsigned long flags;
 	int ret;
 
-	if (!clk)
-		return -EINVAL;
-
-	clk_enable(clk->parent);
-
 	spin_lock_irqsave(&clock_lock, flags);
 	ret = __clk_enable(clk);
 	spin_unlock_irqrestore(&clock_lock, flags);
@@ -135,21 +143,23 @@ int clk_enable(struct clk *clk)
 }
 EXPORT_SYMBOL_GPL(clk_enable);
 
-static void clk_kref_release(struct kref *kref)
-{
-	/* Nothing to do */
-}
-
 static void __clk_disable(struct clk *clk)
 {
-	int count = kref_put(&clk->kref, clk_kref_release);
+	if (!clk)
+		return;
+
+	clk->usecount--;
+
+	WARN_ON(clk->usecount < 0);
 
 	if (clk->flags & CLK_ALWAYS_ENABLED)
 		return;
 
-	if (!count) {	/* count reaches zero, disable the clock */
+	if (clk->usecount = 0) {
 		if (likely(clk->ops && clk->ops->disable))
 			clk->ops->disable(clk);
+
+		__clk_disable(clk->parent);
 	}
 }
 
@@ -157,14 +167,9 @@ void clk_disable(struct clk *clk)
 {
 	unsigned long flags;
 
-	if (!clk)
-		return;
-
 	spin_lock_irqsave(&clock_lock, flags);
 	__clk_disable(clk);
 	spin_unlock_irqrestore(&clock_lock, flags);
-
-	clk_disable(clk->parent);
 }
 EXPORT_SYMBOL_GPL(clk_disable);
 
@@ -173,14 +178,14 @@ int clk_register(struct clk *clk)
 	mutex_lock(&clock_list_sem);
 
 	list_add(&clk->node, &clock_list);
-	kref_init(&clk->kref);
+	clk->usecount = 0;
+	clk->flags |= CLK_NEEDS_INIT;
 
 	mutex_unlock(&clock_list_sem);
 
 	if (clk->flags & CLK_ALWAYS_ENABLED) {
+		__clk_init(clk);
 		pr_debug( "Clock '%s' is ALWAYS_ENABLED\n", clk->name);
-		if (clk->ops && clk->ops->init)
-			clk->ops->init(clk);
 		if (clk->ops && clk->ops->enable)
 			clk->ops->enable(clk);
 		pr_debug( "Enabled.");
@@ -356,7 +361,7 @@ static int show_clocks(char *buf, char *
 		p += sprintf(p, "%-12s\t: %ld.%02ldMHz\t%s\n", clk->name,
 			     rate / 1000000, (rate % 1000000) / 10000,
 			     ((clk->flags & CLK_ALWAYS_ENABLED) ||
-			      (atomic_read(&clk->kref.refcount) != 1)) ?
+			      clk->usecount > 0) ?
 			     "enabled" : "disabled");
 	}
 

Re: [PATCH] sh: clock framework update, fix count and kill off kref

[Paul Mundt]

On Fri, May 08, 2009 at 05:23:29PM +0900, Magnus Damm wrote:
> This patch updates the clock framework use count code.
> With this patch the enable() and disable() callbacks
> only get called when counting from and to zero.
> While at it the kref stuff gets replaced with an int.

On Fri, May 08, 2009 at 05:27:19PM +0900, Magnus Damm wrote:
> This patch enables the TMU clocksource on sh7722.
> To prioritize TMU over CMT we also adjust the CMT
> clock source rating.

On Fri, May 08, 2009 at 05:32:18PM +0900, Magnus Damm wrote:
> This patch adds TMU platform data for sh7723. Both clockevent
> and clocksource support is enabled. While at it, adjust the
> CMT clocksource rating to prioritize the TMU.

Applied, thanks.

Re: [PATCH] sh: clock framework update, fix count and kill off kref

[Francesco VIRLINZI]

Hi Paul
Few days ago I had a discussion with Magnus on the current status of the 
clock framework
and both we agree to change how the .init call back should work.

The design I have in mind is:
 - the .init callback should be called during the clk_registration and
   if the init fails the clock framework rejects the clock.
 - Any operations with (CLK_NEEDS_INIT)  has to be managed internally to
   the clock-SOC implementation via archflag (or a void* private_data) 
to hive any
   implementation issue at clock framework level.

Magnus, Do you want add anything?
Paul, Do you have some issue on this design?

Regards
 Francesco


Paul Mundt ha scritto:
> On Fri, May 08, 2009 at 05:23:29PM +0900, Magnus Damm wrote:
>   
>> This patch updates the clock framework use count code.
>> With this patch the enable() and disable() callbacks
>> only get called when counting from and to zero.
>> While at it the kref stuff gets replaced with an int.
>>     

Re: [PATCH] sh: clock framework update, fix count and kill off kref

[Magnus Damm]

On Mon, May 11, 2009 at 4:34 PM, Francesco VIRLINZI
<francesco.virlinzi@st.com> wrote:
> The design I have in mind is:
> - the .init callback should be called during the clk_registration and
>  if the init fails the clock framework rejects the clock.
> - Any operations with (CLK_NEEDS_INIT)  has to be managed internally to
>  the clock-SOC implementation via archflag (or a void* private_data) to hive
> any
>  implementation issue at clock framework level.
>
> Magnus, Do you want add anything?

Not really, except I have to test it and make sure it will work. =)
There may be historical reasons why the code is written as it is, so
let's try to only call init() from clock registration and see how that
goes. Do you have a patch? =)

/ magnus

Re: [PATCH] sh: clock framework update, fix count and kill off kref

[Francesco VIRLINZI]

Hi Magnus
> Not really, except I have to test it and make sure it will work. =)
> There may be historical reasons why the code is written as it is, so
> let's try to only call init() from clock registration and see how that
> goes. Do you have a patch? =)
>   
I will post it asap, just  the time to rebase my repository.
Regards
 Francesco
> / magnus
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