[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>

1 files changed, 86 insertions, 3 deletions

diff --git a/drivers/watchdog/s3c2410_wdt.c b/drivers/watchdog/s3c2410_wdt.c
index b57ac6b49147..85b93e15d011 100644
--- 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;