clocksource/drivers/timer-of: Add kernel documentation

The current code has no comments, neither any function descriptions. Fix this by
adding function descriptions in kernel doc format.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1515418139-23276-6-git-send-email-daniel.lezcano@linaro.org
[ Spelling and style fixes. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>

drivers/clocksource/timer-of.c

@@ -24,6 +24,12 @@
 
 #include "timer-of.h"
 
+/**
+ * timer_of_irq_exit - Release the interrupt
+ * @of_irq: an of_timer_irq structure pointer
+ *
+ * Free the irq resource
+ */
 static __init void timer_of_irq_exit(struct of_timer_irq *of_irq)
 {
 	struct timer_of *to = container_of(of_irq, struct timer_of, of_irq);
@@ -34,6 +40,22 @@ static __init void timer_of_irq_exit(struct of_timer_irq *of_irq)
 		free_irq(of_irq->irq, clkevt);
 }
 
+/**
+ * timer_of_irq_init - Request the interrupt
+ * @np: a device tree node pointer
+ * @of_irq: an of_timer_irq structure pointer
+ *
+ * Get the interrupt number from the DT from its definition and
+ * request it. The interrupt is gotten by falling back the following way:
+ *
+ * - Get interrupt number by name
+ * - Get interrupt number by index
+ *
+ * When the interrupt is per CPU, 'request_percpu_irq()' is called,
+ * otherwise 'request_irq()' is used.
+ *
+ * Returns 0 on success, < 0 otherwise
+ */
 static __init int timer_of_irq_init(struct device_node *np,
 				    struct of_timer_irq *of_irq)
 {
@@ -72,13 +94,28 @@ static __init int timer_of_irq_init(struct device_node *np,
 	return 0;
 }
 
+/**
+ * timer_of_clk_exit - Release the clock resources
+ * @of_clk: a of_timer_clk structure pointer
+ *
+ * Disables and releases the refcount on the clk
+ */
 static __init void timer_of_clk_exit(struct of_timer_clk *of_clk)
 {
 	of_clk->rate = 0;
 	clk_disable_unprepare(of_clk->clk);
 	clk_put(of_clk->clk);
 }
 
+/**
+ * timer_of_clk_init - Initialize the clock resources
+ * @np: a device tree node pointer
+ * @of_clk: a of_timer_clk structure pointer
+ *
+ * Get the clock by name or by index, enable it and get the rate
+ *
+ * Returns 0 on success, < 0 otherwise
+ */
 static __init int timer_of_clk_init(struct device_node *np,
 				    struct of_timer_clk *of_clk)
 {