soundwire: cadence: multi-link support

Enable multi-link (aka multi-master configuration). In this
configuration, updates and commands with the 'ssp_sync' tag will be
deferred and controlled by the gsync hardware signal.
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20200317163329.25501-17-pierre-louis.bossart@linux.intel.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/soundwire/cadence_master.c

@@ -843,7 +843,13 @@ int sdw_cdns_exit_reset(struct sdw_cdns *cdns)
 		     CDNS_MCP_CONTROL_HW_RST);
 
 	/* commit changes */
-	return cdns_config_update(cdns);
+	cdns_updatel(cdns, CDNS_MCP_CONFIG_UPDATE,
+		     CDNS_MCP_CONFIG_UPDATE_BIT,
+		     CDNS_MCP_CONFIG_UPDATE_BIT);
+
+	/* don't wait here */
+	return 0;
+
 }
 EXPORT_SYMBOL(sdw_cdns_exit_reset);
 
@@ -1104,7 +1110,9 @@ int sdw_cdns_init(struct sdw_cdns *cdns)
 	/* Disable auto bus release */
 	val &= ~CDNS_MCP_CONFIG_BUS_REL;
 
-	/* Multi-master support to be added here */
+	if (cdns->bus.multi_link)
+		/* Set Multi-master mode to take gsync into account */
+		val |= CDNS_MCP_CONFIG_MMASTER;
 
 	/* leave frame delay to hardware default of 0x1F */