clocksource: Add __clocksource_updatefreq_hz/khz methods
To properly handle clocksources that change frequencies
at the clocksource->enable() point, this patch adds
a method that will update the clocksource's mult/shift and
max_idle_ns values.
Signed-off-by: John Stultz <johnstul@us.ibm.com>
LKML-Reference: <1279068988-21864-12-git-send-email-johnstul@us.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
index 21677d9..c37b21a 100644
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -292,6 +292,8 @@
*/
extern int
__clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq);
+extern void
+__clocksource_updatefreq_scale(struct clocksource *cs, u32 scale, u32 freq);
static inline int clocksource_register_hz(struct clocksource *cs, u32 hz)
{
@@ -303,6 +305,15 @@
return __clocksource_register_scale(cs, 1000, khz);
}
+static inline void __clocksource_updatefreq_hz(struct clocksource *cs, u32 hz)
+{
+ __clocksource_updatefreq_scale(cs, 1, hz);
+}
+
+static inline void __clocksource_updatefreq_khz(struct clocksource *cs, u32 khz)
+{
+ __clocksource_updatefreq_scale(cs, 1000, khz);
+}
static inline void
clocksource_calc_mult_shift(struct clocksource *cs, u32 freq, u32 minsec)
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index c543d21..c18d7ef 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -639,6 +639,32 @@
#define MAX_UPDATE_LENGTH 5 /* Seconds */
/**
+ * __clocksource_updatefreq_scale - Used update clocksource with new freq
+ * @t: clocksource to be registered
+ * @scale: Scale factor multiplied against freq to get clocksource hz
+ * @freq: clocksource frequency (cycles per second) divided by scale
+ *
+ * This should only be called from the clocksource->enable() method.
+ *
+ * This *SHOULD NOT* be called directly! Please use the
+ * clocksource_updatefreq_hz() or clocksource_updatefreq_khz helper functions.
+ */
+void __clocksource_updatefreq_scale(struct clocksource *cs, u32 scale, u32 freq)
+{
+ /*
+ * Ideally we want to use some of the limits used in
+ * clocksource_max_deferment, to provide a more informed
+ * MAX_UPDATE_LENGTH. But for now this just gets the
+ * register interface working properly.
+ */
+ clocks_calc_mult_shift(&cs->mult, &cs->shift, freq,
+ NSEC_PER_SEC/scale,
+ MAX_UPDATE_LENGTH*scale);
+ cs->max_idle_ns = clocksource_max_deferment(cs);
+}
+EXPORT_SYMBOL_GPL(__clocksource_updatefreq_scale);
+
+/**
* __clocksource_register_scale - Used to install new clocksources
* @t: clocksource to be registered
* @scale: Scale factor multiplied against freq to get clocksource hz
@@ -652,17 +678,10 @@
int __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq)
{
- /*
- * Ideally we want to use some of the limits used in
- * clocksource_max_deferment, to provide a more informed
- * MAX_UPDATE_LENGTH. But for now this just gets the
- * register interface working properly.
- */
- clocks_calc_mult_shift(&cs->mult, &cs->shift, freq,
- NSEC_PER_SEC/scale,
- MAX_UPDATE_LENGTH*scale);
- cs->max_idle_ns = clocksource_max_deferment(cs);
+ /* Intialize mult/shift and max_idle_ns */
+ __clocksource_updatefreq_scale(cs, scale, freq);
+ /* Add clocksource to the clcoksource list */
mutex_lock(&clocksource_mutex);
clocksource_enqueue(cs);
clocksource_select();