[PATCH 12/23] clocksource: add clocksource_get_clock()

[Daniel Walker <dwalker@mvista.com>]

One new API call clocksource_get_clock() which allows clocks to be selected
based on their name, or if the name is null the highest rated clock is returned.

Signed-Off-By: Daniel Walker <dwalker@mvista.com>

---
 include/linux/clocksource.h |   12 ++++++++++++
 kernel/time/clocksource.c   |   18 ++++++++++++++++++
 2 files changed, 30 insertions(+)

Index: linux-2.6.19/include/linux/clocksource.h
===================================================================
--- linux-2.6.19.orig/include/linux/clocksource.h
+++ linux-2.6.19/include/linux/clocksource.h
@@ -234,6 +234,18 @@ static inline void clocksource_calculate
 extern struct clocksource *clocksource_get_next(void);
 extern int clocksource_register(struct clocksource*);
 extern void clocksource_rating_change(struct clocksource*);
+extern struct clocksource * clocksource_get_clock(char*);
+
+/**
+ * clocksource_get_best_clock - Finds highest rated clocksource
+ *
+ * Returns the highest rated clocksource. If none are register the
+ * jiffies clock is returned.
+ */
+static inline struct clocksource * clocksource_get_best_clock(void)
+{
+	return clocksource_get_clock(NULL);
+}
 
 #ifdef CONFIG_GENERIC_TIME_VSYSCALL
 extern void update_vsyscall(struct timespec *ts, struct clocksource *c);
Index: linux-2.6.19/kernel/time/clocksource.c
===================================================================
--- linux-2.6.19.orig/kernel/time/clocksource.c
+++ linux-2.6.19/kernel/time/clocksource.c
@@ -132,6 +132,24 @@ static inline struct clocksource * __get
 }
 
 /**
+ * clocksource_get_clock - Finds a specific clocksource
+ * @name:		name of the clocksource to return
+ *
+ * Returns the clocksource if registered, zero otherwise.
+ */
+struct clocksource * clocksource_get_clock(char * name)
+{
+	struct clocksource * ret;
+	unsigned long flags;
+
+	spin_lock_irqsave(&clocksource_lock, flags);
+	ret = __get_clock(name);
+	spin_unlock_irqrestore(&clocksource_lock, flags);
+	return ret;
+}
+
+
+/**
  * select_clocksource - Finds the best registered clocksource.
  *
  * Private function. Must hold clocksource_lock when called.

-- 
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