staging: vc04_services: vchiq_arm: Fix initialisation check

The vchiq_state used to be obtained through an accessor which would
validate that the VCHIQ had been initialised correctly with the remote,
or return a null state.

In commit 42a2f66 ("staging: vc04_services: Move global g_state to
vchiq_state") the global state was moved to the vchiq_mgnt structures
stored as a vchiq instance specific context. This conversion removed the
helpers and instead replaced users of this helper with the assumption
that the state is always available and the remote connected.

The conversion does ensure that the state is always available, so some
remaining state null pointer checks that remain are unnecessary, but the
assumption that the remote is present and initialised is incorrect.

Fix this broken assumption by re-introducing the logic that was lost
during the conversion.

Fixes: 42a2f66 ("staging: vc04_services: Move global g_state to vchiq_state")
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Stefan Wahren <wahrenst@gmx.net>
Reviewed-by: Umang Jain <umang.jain@ideasonboard.com>
Link: https://lore.kernel.org/r/20240620221046.2731704-1-kieran.bingham@ideasonboard.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c

@@ -707,7 +707,7 @@ int vchiq_initialise(struct vchiq_state *state, struct vchiq_instance **instance
 	 * block forever.
 	 */
 	for (i = 0; i < VCHIQ_INIT_RETRIES; i++) {
-		if (state)
+		if (vchiq_remote_initialised(state))
 			break;
 		usleep_range(500, 600);
 	}
@@ -1202,7 +1202,7 @@ void vchiq_dump_platform_instances(struct vchiq_state *state, struct seq_file *f
 {
 	int i;
 
-	if (!state)
+	if (!vchiq_remote_initialised(state))
 		return;
 
 	/*

drivers/staging/vc04_services/interface/vchiq_arm/vchiq_core.h

@@ -413,6 +413,11 @@ struct vchiq_state {
 	struct opaque_platform_state *platform_state;
 };
 
+static inline bool vchiq_remote_initialised(const struct vchiq_state *state)
+{
+	return state->remote && state->remote->initialised;
+}
+
 struct bulk_waiter {
 	struct vchiq_bulk *bulk;
 	struct completion event;

drivers/staging/vc04_services/interface/vchiq_arm/vchiq_dev.c

@@ -1170,6 +1170,11 @@ static int vchiq_open(struct inode *inode, struct file *file)
 
 	dev_dbg(state->dev, "arm: vchiq open\n");
 
+	if (!vchiq_remote_initialised(state)) {
+		dev_dbg(state->dev, "arm: vchiq has no connection to VideoCore\n");
+		return -ENOTCONN;
+	}
+
 	instance = kzalloc(sizeof(*instance), GFP_KERNEL);
 	if (!instance)
 		return -ENOMEM;
@@ -1200,7 +1205,7 @@ static int vchiq_release(struct inode *inode, struct file *file)
 
 	dev_dbg(state->dev, "arm: instance=%p\n", instance);
 
-	if (!state) {
+	if (!vchiq_remote_initialised(state)) {
 		ret = -EPERM;
 		goto out;
 	}