firewire: core: add helper functions to access to fw_device data in fw_node structure

The data mbmer in fw_node structure is an opaque pointer, while nowadays
it is just used to refer to fw_device associated with the fw_node.

This commit redefines the opaque pointer to a pointer to fw_device
structure, and adds some helper functions to set/get it.

Link: https://lore.kernel.org/r/20250908012108.514698-5-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>

3 files changed, 23 insertions, 13 deletions

diff --git a/drivers/firewire/core-card.c b/drivers/firewire/core-card.c
index 41902dcc10a0..4a4210cda571 100644
--- a/drivers/firewire/core-card.c
+++ b/drivers/firewire/core-card.c
@@ -307,12 +307,12 @@ static void bm_work(struct work_struct *work)
 	generation = card->generation;
 
 	root_node = fw_node_get(card->root_node);
-	root_device = root_node->data;
+	root_device = fw_node_get_device(root_node);
 	root_device_is_running = root_device &&
 			atomic_read(&root_device->state) == FW_DEVICE_RUNNING;
 	root_device_is_cmc = root_device && root_device->cmc;
 
-	irm_device = card->irm_node->data;
+	irm_device = fw_node_get_device(card->irm_node);
 	irm_is_1394_1995_only = irm_device && irm_device->config_rom &&
 			(irm_device->config_rom[2] & 0x000000f0) == 0;
 
diff --git a/drivers/firewire/core-device.c b/drivers/firewire/core-device.c
index aeacd4cfd694..6a04a0014694 100644
--- a/drivers/firewire/core-device.c
+++ b/drivers/firewire/core-device.c
@@ -887,7 +887,7 @@ static void fw_device_release(struct device *dev)
 	 * bus manager work looks at this node.
 	 */
 	scoped_guard(spinlock_irqsave, &card->lock)
-		device->node->data = NULL;
+		fw_node_set_device(device->node, NULL);
 
 	fw_node_put(device->node);
 	kfree(device->config_rom);
@@ -1007,7 +1007,7 @@ static void fw_device_init(struct work_struct *work)
 	int ret;
 
 	/*
-	 * All failure paths here set node->data to NULL, so that we
+	 * All failure paths here call fw_node_set_device(node, NULL), so that we
 	 * don't try to do device_for_each_child() on a kfree()'d
 	 * device.
 	 */
@@ -1051,9 +1051,9 @@ static void fw_device_init(struct work_struct *work)
 				struct fw_node *obsolete_node = reused->node;
 
 				device->node = obsolete_node;
-				device->node->data = device;
+				fw_node_set_device(device->node, device);
 				reused->node = current_node;
-				reused->node->data = reused;
+				fw_node_set_device(reused->node, reused);
 
 				reused->max_speed = device->max_speed;
 				reused->node_id = current_node->node_id;
@@ -1292,7 +1292,7 @@ void fw_node_event(struct fw_card *card, struct fw_node *node, int event)
 		 * FW_NODE_UPDATED callbacks can update the node_id
 		 * and generation for the device.
 		 */
-		node->data = device;
+		fw_node_set_device(node, device);
 
 		/*
 		 * Many devices are slow to respond after bus resets,
@@ -1307,7 +1307,7 @@ void fw_node_event(struct fw_card *card, struct fw_node *node, int event)
 
 	case FW_NODE_INITIATED_RESET:
 	case FW_NODE_LINK_ON:
-		device = node->data;
+		device = fw_node_get_device(node);
 		if (device == NULL)
 			goto create;
 
@@ -1324,7 +1324,7 @@ void fw_node_event(struct fw_card *card, struct fw_node *node, int event)
 		break;
 
 	case FW_NODE_UPDATED:
-		device = node->data;
+		device = fw_node_get_device(node);
 		if (device == NULL)
 			break;
 
@@ -1339,7 +1339,7 @@ void fw_node_event(struct fw_card *card, struct fw_node *node, int event)
 
 	case FW_NODE_DESTROYED:
 	case FW_NODE_LINK_OFF:
-		if (!node->data)
+		if (!fw_node_get_device(node))
 			break;
 
 		/*
@@ -1354,7 +1354,7 @@ void fw_node_event(struct fw_card *card, struct fw_node *node, int event)
 		 * the device in shutdown state to have that code fail
 		 * to create the device.
 		 */
-		device = node->data;
+		device = fw_node_get_device(node);
 		if (atomic_xchg(&device->state,
 				FW_DEVICE_GONE) == FW_DEVICE_RUNNING) {
 			device->workfn = fw_device_shutdown;
diff --git a/drivers/firewire/core.h b/drivers/firewire/core.h
index 9b298af1cac0..083e39034c37 100644
--- a/drivers/firewire/core.h
+++ b/drivers/firewire/core.h
@@ -194,8 +194,8 @@ struct fw_node {
 	/* For serializing node topology into a list. */
 	struct list_head link;
 
-	/* Upper layer specific data. */
-	void *data;
+	// The device when already associated, else NULL.
+	struct fw_device *device;
 
 	struct fw_node *ports[] __counted_by(port_count);
 };
@@ -219,6 +219,16 @@ static inline void fw_node_put(struct fw_node *node)
 	kref_put(&node->kref, release_node);
 }
 
+static inline struct fw_device *fw_node_get_device(struct fw_node *node)
+{
+	return node->device;
+}
+
+static inline void fw_node_set_device(struct fw_node *node, struct fw_device *device)
+{
+	node->device = device;
+}
+
 void fw_core_handle_bus_reset(struct fw_card *card, int node_id,
 	int generation, int self_id_count, u32 *self_ids, bool bm_abdicate);
 void fw_destroy_nodes(struct fw_card *card);