interconnect: Add get_bw() callback

The interconnect controller hardware may support querying the current
bandwidth settings, so add a callback for providers to implement this
functionality if supported.

Link: https://lore.kernel.org/r/20200825170152.6434-2-georgi.djakov@linaro.org
Reviewed-by: Saravana Kannan <saravanak@google.com>
Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>

include/linux/interconnect-provider.h

@@ -38,6 +38,7 @@ struct icc_node *of_icc_xlate_onecell(struct of_phandle_args *spec,
  * @aggregate: pointer to device specific aggregate operation function
  * @pre_aggregate: pointer to device specific function that is called
  *		   before the aggregation begins (optional)
+ * @get_bw: pointer to device specific function to get current bandwidth
  * @xlate: provider-specific callback for mapping nodes from phandle arguments
  * @dev: the device this interconnect provider belongs to
  * @users: count of active users
@@ -51,6 +52,7 @@ struct icc_provider {
 	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);
+	int (*get_bw)(struct icc_node *node, u32 *avg, u32 *peak);
 	struct icc_node* (*xlate)(struct of_phandle_args *spec, void *data);
 	struct device		*dev;
 	int			users;