HSI: export method to (un)register clients

Expose method for registering and unregistering HSI clients, so that
client drivers can register other client drivers.

This is useful for HSI drivers, which want to use the functionality
of other HSI drivers. For example the N900 modem driver can load HSI
drivers for mcsaab protocol and speech protocol.

Signed-off-by: Sebastian Reichel <[e-mail]>
Reviewed-by: Pavel Machek <[e-mail]>
Tested-By: Ivaylo Dimitrov <[e-mail]>

drivers/hsi/hsi.c

···
 	kfree(cl);
 }
 
-static void hsi_new_client(struct hsi_port *port, struct hsi_board_info *info)
+struct hsi_client *hsi_new_client(struct hsi_port *port,
+						struct hsi_board_info *info)
 {
 	struct hsi_client *cl;
 	size_t size;
 
 	cl = kzalloc(sizeof(*cl), GFP_KERNEL);
 	if (!cl)
-		return;
+		return NULL;
 
 	cl->tx_cfg = info->tx_cfg;
 	if (cl->tx_cfg.channels) {
···
 		pr_err("hsi: failed to register client: %s\n", info->name);
 		put_device(&cl->device);
 	}
+
+	return cl;
 }
+EXPORT_SYMBOL_GPL(hsi_new_client);
 
 static void hsi_scan_board_info(struct hsi_controller *hsi)
 {
···
 		}
 }
 
-static int hsi_remove_client(struct device *dev, void *data __maybe_unused)
+int hsi_remove_client(struct device *dev, void *data __maybe_unused)
 {
 	device_unregister(dev);
 
 	return 0;
 }
+EXPORT_SYMBOL_GPL(hsi_remove_client);
 
 static int hsi_remove_port(struct device *dev, void *data __maybe_unused)
 {

include/linux/hsi/hsi.h

···
 void hsi_put_controller(struct hsi_controller *hsi);
 int hsi_register_controller(struct hsi_controller *hsi);
 void hsi_unregister_controller(struct hsi_controller *hsi);
+struct hsi_client *hsi_new_client(struct hsi_port *port,
+						struct hsi_board_info *info);
+int hsi_remove_client(struct device *dev, void *data);
 void hsi_port_unregister_clients(struct hsi_port *port);
 
 static inline void hsi_controller_set_drvdata(struct hsi_controller *hsi,