diff --git a/include/linux/clk.h b/include/linux/clk.h
index 1d37f42..d6ae10b 100644
--- a/include/linux/clk.h
+++ b/include/linux/clk.h
+#ifdef CONFIG_GENERIC_CLK
+
+struct clk_hw {
+	struct clk *clk;
+};
+
+/**
+ * struct clk_hw_ops -  Callback operations for hardware clocks; these are to
+ * be provided by the clock implementation, and will be called by drivers
+ * through the clk_* API.
+ *
+ * @prepare:	Prepare the clock for enabling. This must not return until
+ *		the clock is fully prepared, and it's safe to call clk_enable.
+ *		This callback is intended to allow clock implementations to
+ *		do any initialisation that may sleep. Called with
+ *		prepare_lock held.
+ *
+ * @unprepare:	Release the clock from its prepared state. This will typically
+ *		undo any work done in the @prepare callback. Called with
+ *		prepare_lock held.
+ *
+ * @enable:	Enable the clock atomically. This must not return until the
+ *		clock is generating a valid clock signal, usable by consumer
+ *		devices. Called with enable_lock held. This function must not
+ *		sleep.
+ *
+ * @disable:	Disable the clock atomically. Called with enable_lock held.
+ *		This function must not sleep.
+ *
+ * @recalc_rate	Recalculate the rate of this clock, by quering hardware
+ *		and/or the clock's parent. Called with the global clock mutex
+ *		held. Optional, but recommended - if this op is not set,
+ *		clk_get_rate will return 0.
+ *
+ * @get_parent	Query the parent of this clock; for clocks with multiple
+ *		possible parents, query the hardware for the current
+ *		parent. Currently only called when the clock is first
+ *		registered.
+ *
+ * The clk_enable/clk_disable and clk_prepare/clk_unprepare pairs allow
+ * implementations to split any work between atomic (enable) and sleepable
+ * (prepare) contexts.  If a clock requires sleeping code to be turned on, this
+ * should be done in clk_prepare. Switching that will not sleep should be done
+ * in clk_enable.
+ *
+ * Typically, drivers will call clk_prepare when a clock may be needed later
+ * (eg. when a device is opened), and clk_enable when the clock is actually
+ * required (eg. from an interrupt). Note that clk_prepare *must* have been
+ * called before clk_enable.
   */
+struct clk_hw_ops {
+	int		(*prepare)(struct clk_hw *);
+	void		(*unprepare)(struct clk_hw *);
+	int		(*enable)(struct clk_hw *);
+	void		(*disable)(struct clk_hw *);
+	unsigned long	(*recalc_rate)(struct clk_hw *);
+	long		(*round_rate)(struct clk_hw *, unsigned long);
+	struct clk *	(*get_parent)(struct clk_hw *);
+};