ARM: LPC32xx: clock.c: Fix mutex lock issues

This patch fixes the mutex issue in clock.c, as done in Kevin Wells' original
driver update:

In some cases, the clock drivers could grab a mutex twice in an improper
context. This patch changes the mutex mechanism to a simple irq lock/unlock
mechanism and removes un-needed locks from some functions.

(See also git.lpclinux.com)

Signed-off-by: Roland Stigge <stigge@antcom.de>
Tested-by: Wolfram Sang <w.sang@pengutronix.de>
Acked-by: Kevin Wells <kevin.wells@nxp.com>
Signed-off-by: Olof Johansson <olof@lixom.net>

1 files changed, 11 insertions, 30 deletions

diff --git a/arch/arm/mach-lpc32xx/clock.c b/arch/arm/mach-lpc32xx/clock.c
index 39dcbd0e68b2..fef863062a5e 100644
--- a/arch/arm/mach-lpc32xx/clock.c
+++ b/arch/arm/mach-lpc32xx/clock.c
@@ -97,9 +97,10 @@
 #include "clock.h"
 #include "common.h"
 
+static DEFINE_SPINLOCK(global_clkregs_lock);
+
 static struct clk clk_armpll;
 static struct clk clk_usbpll;
-static DEFINE_MUTEX(clkm_lock);
 
 /*
  * Post divider values for PLLs based on selected register value
@@ -891,16 +892,6 @@ static struct clk clk_lcd = {
         .enable_mask    = LPC32XX_CLKPWR_LCDCTRL_CLK_EN,
 };
 
-static inline void clk_lock(void)
-{
-        mutex_lock(&clkm_lock);
-}
-
-static inline void clk_unlock(void)
-{
-        mutex_unlock(&clkm_lock);
-}
-
 static void local_clk_disable(struct clk *clk)
 {
         /* Don't attempt to disable clock if it has no users */
@@ -945,10 +936,11 @@ static int local_clk_enable(struct clk *clk)
 int clk_enable(struct clk *clk)
 {
         int ret;
+        unsigned long flags;
 
-        clk_lock();
+        spin_lock_irqsave(&global_clkregs_lock, flags);
         ret = local_clk_enable(clk);
-        clk_unlock();
+        spin_unlock_irqrestore(&global_clkregs_lock, flags);
 
         return ret;
 }
@@ -959,9 +951,11 @@ EXPORT_SYMBOL(clk_enable);
  */
 void clk_disable(struct clk *clk)
 {
-        clk_lock();
+        unsigned long flags;
+
+        spin_lock_irqsave(&global_clkregs_lock, flags);
         local_clk_disable(clk);
-        clk_unlock();
+        spin_unlock_irqrestore(&global_clkregs_lock, flags);
 }
 EXPORT_SYMBOL(clk_disable);
 
@@ -970,13 +964,7 @@ EXPORT_SYMBOL(clk_disable);
  */
 unsigned long clk_get_rate(struct clk *clk)
 {
-        unsigned long rate;
-
-        clk_lock();
-        rate = clk->get_rate(clk);
-        clk_unlock();
-
-        return rate;
+        return clk->get_rate(clk);
 }
 EXPORT_SYMBOL(clk_get_rate);
 
@@ -992,11 +980,8 @@ int clk_set_rate(struct clk *clk, unsigned long rate)
          * the actual rate set as part of the peripheral dividers
          * instead of high level clock control
          */
-        if (clk->set_rate) {
-                clk_lock();
+        if (clk->set_rate)
                 ret = clk->set_rate(clk, rate);
-                clk_unlock();
-        }
 
         return ret;
 }
@@ -1007,15 +992,11 @@ EXPORT_SYMBOL(clk_set_rate);
  */
 long clk_round_rate(struct clk *clk, unsigned long rate)
 {
-        clk_lock();
-
         if (clk->round_rate)
                 rate = clk->round_rate(clk, rate);
         else
                 rate = clk->get_rate(clk);
 
-        clk_unlock();
-
         return rate;
 }
 EXPORT_SYMBOL(clk_round_rate);