2009-10-30 00:30:37

by Ben Dooks

Subject: CPUFREQ: S3C24XX Watchdog frequency scaling support.

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

Signed-off-by: Simtec Linux Team <[email protected]>
Signed-off-by: Ben Dooks <[email protected]>

---
drivers/watchdog/s3c2410_wdt.c | 89 +++++++++++++++++++++++++++++++++++++++--
1 file changed, 86 insertions(+), 3 deletions(-)

Index: b/drivers/watchdog/s3c2410_wdt.c
===================================================================
--- a/drivers/watchdog/s3c2410_wdt.c 2009-08-28 11:44:05.000000000 +0100
+++ b/drivers/watchdog/s3c2410_wdt.c 2009-08-28 11:55:47.000000000 +0100
@@ -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
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 ir
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(st

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(st
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(st

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(st

static int __devexit s3c2410wdt_remove(struct platform_device *dev)
{
+ s3c2410wdt_cpufreq_deregister();
+
release_resource(wdt_mem);
kfree(wdt_mem);
wdt_mem = NULL;

--
Ben ([email protected], http://www.fluff.org/)

'a smiley only costs 4 bytes'

2009-11-02 12:34:10

by Wim Van Sebroeck

Subject: Re: CPUFREQ: S3C24XX Watchdog frequency scaling support.

Hi Ben,

> Add support for CPU frequency scaling to the S3C24XX Watchdog
> driver.
>
> Signed-off-by: Simtec Linux Team <[email protected]>
> Signed-off-by: Ben Dooks <[email protected]>

Added to the linux-2.6-watchdog-next tree.

Kind regards,
Wim.