interconnect: Add pre_aggregate() callback

Introduce an optional callback in interconnect provider drivers. It can be
used for implementing actions, that need to be executed before the actual
aggregation of the bandwidth requests has started.

The benefit of this for now is that it will significantly simplify the code
in provider drivers.
Suggested-by: Evan Green <evgreen@chromium.org>
Reviewed-by: Evan Green <evgreen@chromium.org>
Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>

drivers/interconnect/core.c

@@ -205,6 +205,9 @@ static int aggregate_requests(struct icc_node *node)
 	node->avg_bw = 0;
 	node->peak_bw = 0;
 
+	if (p->pre_aggregate)
+		p->pre_aggregate(node);
+
 	hlist_for_each_entry(r, &node->req_list, req_node)
 		p->aggregate(node, r->tag, r->avg_bw, r->peak_bw,
 			     &node->avg_bw, &node->peak_bw);

include/linux/interconnect-provider.h

@@ -36,6 +36,8 @@ struct icc_node *of_icc_xlate_onecell(struct of_phandle_args *spec,
  * @nodes: internal list of the interconnect provider nodes
  * @set: pointer to device specific set operation function
  * @aggregate: pointer to device specific aggregate operation function
+ * @pre_aggregate: pointer to device specific function that is called
+ *		   before the aggregation begins (optional)
  * @xlate: provider-specific callback for mapping nodes from phandle arguments
  * @dev: the device this interconnect provider belongs to
  * @users: count of active users
@@ -47,6 +49,7 @@ struct icc_provider {
 	int (*set)(struct icc_node *src, struct icc_node *dst);
 	int (*aggregate)(struct icc_node *node, u32 tag, u32 avg_bw,
 			 u32 peak_bw, u32 *agg_avg, u32 *agg_peak);
+	void (*pre_aggregate)(struct icc_node *node);
 	struct icc_node* (*xlate)(struct of_phandle_args *spec, void *data);
 	struct device		*dev;
 	int			users;