[WATCHDOG] CPUFREQ: S3C24XX Watchdog frequency scaling support.

Add support for CPU frequency scaling to the S3C24XX Watchdog
driver.

Signed-off-by: Simtec Linux Team <linux@simtec.co.uk>
Signed-off-by: Ben Dooks <ben@simtec.co.uk>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

diff --git a/drivers/watchdog/s3c2410_wdt.c b/drivers/watchdog/s3c2410_wdt.c
index b57ac6b49147400a0230a777b81592202947a439..85b93e15d01122aefad8c9433221670041afde97 100644 (file)
--- a/drivers/watchdog/s3c2410_wdt.c
+++ b/drivers/watchdog/s3c2410_wdt.c
@@ -36,6 +36,7 @@
 #include <linux/clk.h>
 #include <linux/uaccess.h>
 #include <linux/io.h>
+#include <linux/cpufreq.h>
 
 #include <mach/map.h>
 
@@ -142,9 +143,14 @@ static void s3c2410wdt_start(void)
        spin_unlock(&wdt_lock);
 }
 
+static inline int s3c2410wdt_is_running(void)
+{
+       return readl(wdt_base + S3C2410_WTCON) & S3C2410_WTCON_ENABLE;
+}
+
 static int s3c2410wdt_set_heartbeat(int timeout)
 {
-       unsigned int freq = clk_get_rate(wdt_clock);
+       unsigned long freq = clk_get_rate(wdt_clock);
        unsigned int count;
        unsigned int divisor = 1;
        unsigned long wtcon;
@@ -155,7 +161,7 @@ static int s3c2410wdt_set_heartbeat(int timeout)
        freq /= 128;
        count = timeout * freq;
 
-       DBG("%s: count=%d, timeout=%d, freq=%d\n",
+       DBG("%s: count=%d, timeout=%d, freq=%lu\n",
            __func__, count, timeout, freq);
 
        /* if the count is bigger than the watchdog register,
@@ -324,6 +330,73 @@ static irqreturn_t s3c2410wdt_irq(int irqno, void *param)
        s3c2410wdt_keepalive();
        return IRQ_HANDLED;
 }
+
+
+#ifdef CONFIG_CPU_FREQ
+
+static int s3c2410wdt_cpufreq_transition(struct notifier_block *nb,
+                                         unsigned long val, void *data)
+{
+       int ret;
+
+       if (!s3c2410wdt_is_running())
+               goto done;
+
+       if (val == CPUFREQ_PRECHANGE) {
+               /* To ensure that over the change we don't cause the
+                * watchdog to trigger, we perform an keep-alive if
+                * the watchdog is running.
+                */
+
+               s3c2410wdt_keepalive();
+       } else if (val == CPUFREQ_POSTCHANGE) {
+               s3c2410wdt_stop();
+
+               ret = s3c2410wdt_set_heartbeat(tmr_margin);
+
+               if (ret >= 0)
+                       s3c2410wdt_start();
+               else
+                       goto err;
+       }
+
+done:
+       return 0;
+
+ err:
+       dev_err(wdt_dev, "cannot set new value for timeout %d\n", tmr_margin);
+       return ret;
+}
+
+static struct notifier_block s3c2410wdt_cpufreq_transition_nb = {
+       .notifier_call  = s3c2410wdt_cpufreq_transition,
+};
+
+static inline int s3c2410wdt_cpufreq_register(void)
+{
+       return cpufreq_register_notifier(&s3c2410wdt_cpufreq_transition_nb,
+                                        CPUFREQ_TRANSITION_NOTIFIER);
+}
+
+static inline void s3c2410wdt_cpufreq_deregister(void)
+{
+       cpufreq_unregister_notifier(&s3c2410wdt_cpufreq_transition_nb,
+                                   CPUFREQ_TRANSITION_NOTIFIER);
+}
+
+#else
+static inline int s3c2410wdt_cpufreq_register(void)
+{
+       return 0;
+}
+
+static inline void s3c2410wdt_cpufreq_deregister(void)
+{
+}
+#endif
+
+
+
 /* device interface */
 
 static int __devinit s3c2410wdt_probe(struct platform_device *pdev)
@@ -387,6 +460,11 @@ static int __devinit s3c2410wdt_probe(struct platform_device *pdev)
 
        clk_enable(wdt_clock);
 
+       if (s3c2410wdt_cpufreq_register() < 0) {
+               printk(KERN_ERR PFX "failed to register cpufreq\n");
+               goto err_clk;
+       }
+
        /* see if we can actually set the requested timer margin, and if
         * not, try the default value */
 
@@ -407,7 +485,7 @@ static int __devinit s3c2410wdt_probe(struct platform_device *pdev)
        if (ret) {
                dev_err(dev, "cannot register miscdev on minor=%d (%d)\n",
                        WATCHDOG_MINOR, ret);
-               goto err_clk;
+               goto err_cpufreq;
        }
 
        if (tmr_atboot && started == 0) {
@@ -432,6 +510,9 @@ static int __devinit s3c2410wdt_probe(struct platform_device *pdev)
 
        return 0;
 
+ err_cpufreq:
+       s3c2410wdt_cpufreq_deregister();
+
  err_clk:
        clk_disable(wdt_clock);
        clk_put(wdt_clock);
@@ -451,6 +532,8 @@ static int __devinit s3c2410wdt_probe(struct platform_device *pdev)
 
 static int __devexit s3c2410wdt_remove(struct platform_device *dev)
 {
+       s3c2410wdt_cpufreq_deregister();
+
        release_resource(wdt_mem);
        kfree(wdt_mem);
        wdt_mem = NULL;