soundwire: intel: introduce a helper to arm link synchronization

Move code from pre_bank_switch to dedicated helper, will be used in
follow-up patches as recommended by programming flows.
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Link: https://lore.kernel.org/r/20200716150947.22119-4-yung-chuan.liao@linux.intel.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/soundwire/intel.c

@@ -497,6 +497,21 @@ static int __maybe_unused intel_link_power_down(struct sdw_intel *sdw)
 	return 0;
 }
 
+static void intel_shim_sync_arm(struct sdw_intel *sdw)
+{
+	void __iomem *shim = sdw->link_res->shim;
+	u32 sync_reg;
+
+	mutex_lock(sdw->link_res->shim_lock);
+
+	/* update SYNC register */
+	sync_reg = intel_readl(shim, SDW_SHIM_SYNC);
+	sync_reg |= (SDW_SHIM_SYNC_CMDSYNC << sdw->instance);
+	intel_writel(shim, SDW_SHIM_SYNC, sync_reg);
+
+	mutex_unlock(sdw->link_res->shim_lock);
+}
+
 /*
  * PDI routines
  */
@@ -710,21 +725,12 @@ static int intel_pre_bank_switch(struct sdw_bus *bus)
 {
 	struct sdw_cdns *cdns = bus_to_cdns(bus);
 	struct sdw_intel *sdw = cdns_to_intel(cdns);
-	void __iomem *shim = sdw->link_res->shim;
-	int sync_reg;
 
 	/* Write to register only for multi-link */
 	if (!bus->multi_link)
 		return 0;
 
-	mutex_lock(sdw->link_res->shim_lock);
-
-	/* Read SYNC register */
-	sync_reg = intel_readl(shim, SDW_SHIM_SYNC);
-	sync_reg |= SDW_SHIM_SYNC_CMDSYNC << sdw->instance;
-	intel_writel(shim, SDW_SHIM_SYNC, sync_reg);
-
-	mutex_unlock(sdw->link_res->shim_lock);
+	intel_shim_sync_arm(sdw);
 
 	return 0;
 }