soundwire: add read_ping_status helper definition in manager ops

The existing manager ops provide callbacks to transfer read/write
commands, but don't allow for direct access to PING status
register. This is accessible in all existing IP, and would help
diagnose timeouts or resume issues by reporting the 'true' status
instead of the internal status reported by the IP.

Signed-off-by: Pierre-Louis Bossart <[email protected]>
Reviewed-by: Rander Wang <[email protected]>
Signed-off-by: Bard Liao <[email protected]>
Acked-By: Vinod Koul <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Mark Brown <[email protected]>

include/linux/soundwire/sdw.h

@@ -839,6 +839,8 @@ struct sdw_defer {
  * @set_bus_conf: Set the bus configuration
  * @pre_bank_switch: Callback for pre bank switch
  * @post_bank_switch: Callback for post bank switch
+ * @read_ping_status: Read status from PING frames, reported with two bits per Device.
+ * Bits 31:24 are reserved.
  */
 struct sdw_master_ops {
 	int (*read_prop)(struct sdw_bus *bus);
@@ -855,6 +857,7 @@ struct sdw_master_ops {
 			struct sdw_bus_params *params);
 	int (*pre_bank_switch)(struct sdw_bus *bus);
 	int (*post_bank_switch)(struct sdw_bus *bus);
+	u32 (*read_ping_status)(struct sdw_bus *bus);
 
 };