soundwire: bus: add unique bus id

Adding an unique id for each bus.
Suggested-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Acked-by: Jaroslav Kysela <perex@perex.cz>
Link: https://lore.kernel.org/r/20200518174322.31561-4-yung-chuan.liao@linux.intel.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/soundwire/bus.c

@@ -9,6 +9,19 @@
 #include <linux/soundwire/sdw.h>
 #include "bus.h"
 
+static DEFINE_IDA(sdw_ida);
+
+static int sdw_get_id(struct sdw_bus *bus)
+{
+	int rc = ida_alloc(&sdw_ida, GFP_KERNEL);
+
+	if (rc < 0)
+		return rc;
+
+	bus->id = rc;
+	return 0;
+}
+
 /**
  * sdw_bus_master_add() - add a bus Master instance
  * @bus: bus instance
@@ -29,6 +42,12 @@ int sdw_bus_master_add(struct sdw_bus *bus, struct device *parent,
 		return -ENODEV;
 	}
 
+	ret = sdw_get_id(bus);
+	if (ret) {
+		dev_err(bus->dev, "Failed to get bus id\n");
+		return ret;
+	}
+
 	if (!bus->ops) {
 		dev_err(bus->dev, "SoundWire Bus ops are not set\n");
 		return -EINVAL;
@@ -144,6 +163,7 @@ void sdw_bus_master_delete(struct sdw_bus *bus)
 	device_for_each_child(bus->dev, NULL, sdw_delete_slave);
 
 	sdw_bus_debugfs_exit(bus);
+	ida_free(&sdw_ida, bus->id);
 }
 EXPORT_SYMBOL(sdw_bus_master_delete);
 

include/linux/soundwire/sdw.h

@@ -789,6 +789,7 @@ struct sdw_master_ops {
  * struct sdw_bus - SoundWire bus
  * @dev: Master linux device
  * @link_id: Link id number, can be 0 to N, unique for each Master
+ * @id: bus system-wide unique id
  * @slaves: list of Slaves on this bus
  * @assigned: Bitmap for Slave device numbers.
  * Bit set implies used number, bit clear implies unused number.
@@ -813,6 +814,7 @@ struct sdw_master_ops {
 struct sdw_bus {
 	struct device *dev;
 	unsigned int link_id;
+	int id;
 	struct list_head slaves;
 	DECLARE_BITMAP(assigned, SDW_MAX_DEVICES);
 	struct mutex bus_lock;