From 3d1443574a09591aaacb0100621c39d4978d5ef1 Mon Sep 17 00:00:00 2001
From: Ben Dooks <ben-linux@fluff.org>
Date: Tue, 21 Oct 2008 14:06:37 +0100
Subject: [ARM] S3C24XX: Change clock locking to use spinlocks.

We cannot sleep if we have cpufreq pm enabled during some
of the clock operations, so change to use a spinlock to
protect the clock system.

Signed-off-by: Ben Dooks <ben-linux@fluff.org>
---
 arch/arm/plat-s3c24xx/clock.c | 32 ++++++++++++++++++--------------
 1 file changed, 18 insertions(+), 14 deletions(-)

(limited to 'arch/arm/plat-s3c24xx/clock.c')

diff --git a/arch/arm/plat-s3c24xx/clock.c b/arch/arm/plat-s3c24xx/clock.c
index 1ff1b983604..334e696200b 100644
--- a/arch/arm/plat-s3c24xx/clock.c
+++ b/arch/arm/plat-s3c24xx/clock.c
@@ -37,7 +37,7 @@
 #include <linux/interrupt.h>
 #include <linux/ioport.h>
 #include <linux/clk.h>
-#include <linux/mutex.h>
+#include <linux/spinlock.h>
 #include <linux/delay.h>
 #include <linux/io.h>
 
@@ -55,7 +55,11 @@
 
 static LIST_HEAD(clocks);
 
-DEFINE_MUTEX(clocks_mutex);
+/* We originally used an mutex here, but some contexts (see resume)
+ * are calling functions such as clk_set_parent() with IRQs disabled
+ * causing an BUG to be triggered.
+ */
+DEFINE_SPINLOCK(clocks_lock);
 
 /* enable and disable calls for use with the clk struct */
 
@@ -77,7 +81,7 @@ struct clk *clk_get(struct device *dev, const char *id)
 	else
 		idno = to_platform_device(dev)->id;
 
-	mutex_lock(&clocks_mutex);
+	spin_lock(&clocks_lock);
 
 	list_for_each_entry(p, &clocks, list) {
 		if (p->id == idno &&
@@ -101,7 +105,7 @@ struct clk *clk_get(struct device *dev, const char *id)
 		}
 	}
 
-	mutex_unlock(&clocks_mutex);
+	spin_unlock(&clocks_lock);
 	return clk;
 }
 
@@ -117,12 +121,12 @@ int clk_enable(struct clk *clk)
 
 	clk_enable(clk->parent);
 
-	mutex_lock(&clocks_mutex);
+	spin_lock(&clocks_lock);
 
 	if ((clk->usage++) == 0)
 		(clk->enable)(clk, 1);
 
-	mutex_unlock(&clocks_mutex);
+	spin_unlock(&clocks_lock);
 	return 0;
 }
 
@@ -131,12 +135,12 @@ void clk_disable(struct clk *clk)
 	if (IS_ERR(clk) || clk == NULL)
 		return;
 
-	mutex_lock(&clocks_mutex);
+	spin_lock(&clocks_lock);
 
 	if ((--clk->usage) == 0)
 		(clk->enable)(clk, 0);
 
-	mutex_unlock(&clocks_mutex);
+	spin_unlock(&clocks_lock);
 	clk_disable(clk->parent);
 }
 
@@ -182,9 +186,9 @@ int clk_set_rate(struct clk *clk, unsigned long rate)
 	if (clk->set_rate == NULL)
 		return -EINVAL;
 
-	mutex_lock(&clocks_mutex);
+	spin_lock(&clocks_lock);
 	ret = (clk->set_rate)(clk, rate);
-	mutex_unlock(&clocks_mutex);
+	spin_unlock(&clocks_lock);
 
 	return ret;
 }
@@ -201,12 +205,12 @@ int clk_set_parent(struct clk *clk, struct clk *parent)
 	if (IS_ERR(clk))
 		return -EINVAL;
 
-	mutex_lock(&clocks_mutex);
+	spin_lock(&clocks_lock);
 
 	if (clk->set_parent)
 		ret = (clk->set_parent)(clk, parent);
 
-	mutex_unlock(&clocks_mutex);
+	spin_unlock(&clocks_lock);
 
 	return ret;
 }
@@ -302,9 +306,9 @@ int s3c24xx_register_clock(struct clk *clk)
 
 	/* add to the list of available clocks */
 
-	mutex_lock(&clocks_mutex);
+	spin_lock(&clocks_lock);
 	list_add(&clk->list, &clocks);
-	mutex_unlock(&clocks_mutex);
+	spin_unlock(&clocks_lock);
 
 	return 0;
 }
-- 
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