[ARM] 3303/1: S3C24XX - add clock enable usage counting

Patch from Ben Dooks

Move to using an enable count for the shared clocks
and protect the clock system using a mutex instead
of just disabling IRQs during the clock update.

Since there is little more code in the path for
non-shared clocks, the enable and disable calls
use the same code for each.

Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

2 files changed, 34 insertions, 10 deletions

diff --git a/arch/arm/mach-s3c2410/clock.c b/arch/arm/mach-s3c2410/clock.c
index af2f3d52b61b..08489efdaf06 100644
--- a/arch/arm/mach-s3c2410/clock.c
+++ b/arch/arm/mach-s3c2410/clock.c
@@ -40,7 +40,6 @@
 #include <linux/mutex.h>
 
 #include <asm/hardware.h>
-#include <asm/atomic.h>
 #include <asm/irq.h>
 #include <asm/io.h>
 
@@ -59,22 +58,18 @@ static DEFINE_MUTEX(clocks_mutex);
 void inline s3c24xx_clk_enable(unsigned int clocks, unsigned int enable)
 {
         unsigned long clkcon;
-        unsigned long flags;
-
-        local_irq_save(flags);
 
         clkcon = __raw_readl(S3C2410_CLKCON);
-        clkcon &= ~clocks;
 
         if (enable)
                 clkcon |= clocks;
+        else
+                clkcon &= ~clocks;
 
         /* ensure none of the special function bits set */
         clkcon &= ~(S3C2410_CLKCON_IDLE|S3C2410_CLKCON_POWER);
 
         __raw_writel(clkcon, S3C2410_CLKCON);
-
-        local_irq_restore(flags);
 }
 
 /* enable and disable calls for use with the clk struct */
@@ -138,16 +133,32 @@ void clk_put(struct clk *clk)
 
 int clk_enable(struct clk *clk)
 {
-        if (IS_ERR(clk))
+        if (IS_ERR(clk) || clk == NULL)
                 return -EINVAL;
 
-        return (clk->enable)(clk, 1);
+        clk_enable(clk->parent);
+
+        mutex_lock(&clocks_mutex);
+
+        if ((clk->usage++) == 0)
+                (clk->enable)(clk, 1);
+
+        mutex_unlock(&clocks_mutex);
+        return 0;
 }
 
 void clk_disable(struct clk *clk)
 {
-        if (!IS_ERR(clk))
+        if (IS_ERR(clk) || clk == NULL)
+                return;
+
+        mutex_lock(&clocks_mutex);
+
+        if ((--clk->usage) == 0)
                 (clk->enable)(clk, 0);
+
+        mutex_unlock(&clocks_mutex);
+        clk_disable(clk->parent);
 }
 
 
@@ -361,6 +372,14 @@ int s3c24xx_register_clock(struct clk *clk)
         if (clk->enable == NULL)
                 clk->enable = clk_null_enable;
 
+        /* if this is a standard clock, set the usage state */
+
+        if (clk->ctrlbit) {
+                unsigned long clkcon = __raw_readl(S3C2410_CLKCON);
+
+                clk->usage = (clkcon & clk->ctrlbit) ? 1 : 0;
+        }
+
         /* add to the list of available clocks */
 
         mutex_lock(&clocks_mutex);
@@ -402,6 +421,8 @@ int __init s3c24xx_setup_clocks(unsigned long xtal,
          * the LCD clock if it is not needed.
         */
 
+        mutex_lock(&clocks_mutex);
+
         s3c24xx_clk_enable(S3C2410_CLKCON_NAND, 0);
         s3c24xx_clk_enable(S3C2410_CLKCON_USBH, 0);
         s3c24xx_clk_enable(S3C2410_CLKCON_USBD, 0);
@@ -409,6 +430,8 @@ int __init s3c24xx_setup_clocks(unsigned long xtal,
         s3c24xx_clk_enable(S3C2410_CLKCON_IIC, 0);
         s3c24xx_clk_enable(S3C2410_CLKCON_SPI, 0);
 
+        mutex_unlock(&clocks_mutex);
+
         /* assume uart clocks are correctly setup */
 
         /* register our clocks */
diff --git a/arch/arm/mach-s3c2410/clock.h b/arch/arm/mach-s3c2410/clock.h
index 177d5c8decf7..eb5c95d1e7f2 100644
--- a/arch/arm/mach-s3c2410/clock.h
+++ b/arch/arm/mach-s3c2410/clock.h
@@ -16,6 +16,7 @@ struct clk {
         struct clk           *parent;
         const char           *name;
         int                   id;
+        int                   usage;
         unsigned long         rate;
         unsigned long         ctrlbit;
         int                 (*enable)(struct clk *, int enable);