soundwire: intel: read mclk_freq property from firmware

The BIOS provides an Intel-specific property, let's use it to avoid
hard-coded clock dividers.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20190806005522.22642-12-pierre-louis.bossart@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

drivers/soundwire/intel.c

@@ -808,11 +808,37 @@ static int intel_register_dai(struct sdw_intel *sdw)
 					  dais, num_dai);
 }
 
+static int sdw_master_read_intel_prop(struct sdw_bus *bus)
+{
+	struct sdw_master_prop *prop = &bus->prop;
+	struct fwnode_handle *link;
+	char name[32];
+	int nval, i;
+
+	/* Find master handle */
+	snprintf(name, sizeof(name),
+		 "mipi-sdw-link-%d-subproperties", bus->link_id);
+
+	link = device_get_named_child_node(bus->dev, name);
+	if (!link) {
+		dev_err(bus->dev, "Master node %s not found\n", name);
+		return -EIO;
+	}
+
+	fwnode_property_read_u32(link,
+				 "intel-sdw-ip-clock",
+				 &prop->mclk_freq);
+	return 0;
+}
+
 static int intel_prop_read(struct sdw_bus *bus)
 {
 	/* Initialize with default handler to read all DisCo properties */
 	sdw_master_read_prop(bus);
 
+	/* read Intel-specific properties */
+	sdw_master_read_intel_prop(bus);
+
 	return 0;
 }