scsi: target: usb: Replace enable attr with ops.enable

Remove tpg/enable attribute.  Add fabric ops enable_tpg implementation
instead.

Link: https://lore.kernel.org/r/20210910084133.17956-8-d.bogdanov@yadro.comReviewed-by: Roman Bolshakov <r.bolshakov@yadro.com>
Reviewed-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Dmitry Bogdanov <d.bogdanov@yadro.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/usb/gadget/function/f_tcm.c

@@ -1495,42 +1495,24 @@ static struct configfs_attribute *usbg_wwn_attrs[] = {
 	NULL,
 };
 
-static ssize_t tcm_usbg_tpg_enable_show(struct config_item *item, char *page)
-{
-	struct se_portal_group *se_tpg = to_tpg(item);
-	struct usbg_tpg  *tpg = container_of(se_tpg, struct usbg_tpg, se_tpg);
-
-	return snprintf(page, PAGE_SIZE, "%u\n", tpg->gadget_connect);
-}
-
 static int usbg_attach(struct usbg_tpg *);
 static void usbg_detach(struct usbg_tpg *);
 
-static ssize_t tcm_usbg_tpg_enable_store(struct config_item *item,
-		const char *page, size_t count)
+static int usbg_enable_tpg(struct se_portal_group *se_tpg, bool enable)
 {
-	struct se_portal_group *se_tpg = to_tpg(item);
 	struct usbg_tpg  *tpg = container_of(se_tpg, struct usbg_tpg, se_tpg);
-	bool op;
-	ssize_t ret;
-
-	ret = strtobool(page, &op);
-	if (ret)
-		return ret;
-
-	if ((op && tpg->gadget_connect) || (!op && !tpg->gadget_connect))
-		return -EINVAL;
+	int ret = 0;
 
-	if (op)
+	if (enable)
 		ret = usbg_attach(tpg);
 	else
 		usbg_detach(tpg);
 	if (ret)
 		return ret;
 
-	tpg->gadget_connect = op;
+	tpg->gadget_connect = enable;
 
-	return count;
+	return 0;
 }
 
 static ssize_t tcm_usbg_tpg_nexus_show(struct config_item *item, char *page)
@@ -1673,11 +1655,9 @@ static ssize_t tcm_usbg_tpg_nexus_store(struct config_item *item,
 	return count;
 }
 
-CONFIGFS_ATTR(tcm_usbg_tpg_, enable);
 CONFIGFS_ATTR(tcm_usbg_tpg_, nexus);
 
 static struct configfs_attribute *usbg_base_attrs[] = {
-	&tcm_usbg_tpg_attr_enable,
 	&tcm_usbg_tpg_attr_nexus,
 	NULL,
 };
@@ -1730,6 +1710,7 @@ static const struct target_core_fabric_ops usbg_ops = {
 	.fabric_make_wwn		= usbg_make_tport,
 	.fabric_drop_wwn		= usbg_drop_tport,
 	.fabric_make_tpg		= usbg_make_tpg,
+	.fabric_enable_tpg		= usbg_enable_tpg,
 	.fabric_drop_tpg		= usbg_drop_tpg,
 	.fabric_post_link		= usbg_port_link,
 	.fabric_pre_unlink		= usbg_port_unlink,