staging: vc04_services: Drop vchiq_connected.[ch] files

The vchiq_connected.[ch] just implements two function:

- vchiq_add_connected_callback()
- vchiq_call_connected_callbacks()

for the deferred vchiq callbacks. Those can easily live in
vchiq_arm.[ch], hence move them. This allows making the
vchiq_call_connected_callbacks() function static.

The move doesn't copy over MAX_CALLBACKS because it is the same as
VCHIQ_DRV_MAX_CALLBACKS. Hence, it now being used in
vchiq_add_connected_callback().

No functional changes intended in this patch.

Suggested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Umang Jain <umang.jain@ideasonboard.com>
Link: https://lore.kernel.org/r/20240412075743.60712-6-umang.jain@ideasonboard.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/vc04_services/Makefile

@@ -6,7 +6,6 @@ vchiq-objs := \
    interface/vchiq_arm/vchiq_arm.o \
    interface/vchiq_arm/vchiq_bus.o \
    interface/vchiq_arm/vchiq_debugfs.o \
-   interface/vchiq_arm/vchiq_connected.o \
 
 ifdef CONFIG_VCHIQ_CDEV
 vchiq-objs += interface/vchiq_arm/vchiq_dev.o

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

@@ -36,7 +36,6 @@
 #include "vchiq_arm.h"
 #include "vchiq_bus.h"
 #include "vchiq_debugfs.h"
-#include "vchiq_connected.h"
 #include "vchiq_pagelist.h"
 
 #define DEVICE_NAME "vchiq"
@@ -189,6 +188,56 @@ is_adjacent_block(u32 *addrs, u32 addr, unsigned int k)
 	return tmp == (addr & PAGE_MASK);
 }
 
+/*
+ * This function is called by the vchiq stack once it has been connected to
+ * the videocore and clients can start to use the stack.
+ */
+static void vchiq_call_connected_callbacks(struct vchiq_drv_mgmt *drv_mgmt)
+{
+	int i;
+
+	if (mutex_lock_killable(&drv_mgmt->connected_mutex))
+		return;
+
+	for (i = 0; i < drv_mgmt->num_deferred_callbacks; i++)
+		drv_mgmt->deferred_callback[i]();
+
+	drv_mgmt->num_deferred_callbacks = 0;
+	drv_mgmt->connected = true;
+	mutex_unlock(&drv_mgmt->connected_mutex);
+}
+
+/*
+ * This function is used to defer initialization until the vchiq stack is
+ * initialized. If the stack is already initialized, then the callback will
+ * be made immediately, otherwise it will be deferred until
+ * vchiq_call_connected_callbacks is called.
+ */
+void vchiq_add_connected_callback(struct vchiq_device *device, void (*callback)(void))
+{
+	struct vchiq_drv_mgmt *drv_mgmt = device->drv_mgmt;
+
+	if (mutex_lock_killable(&drv_mgmt->connected_mutex))
+		return;
+
+	if (drv_mgmt->connected) {
+		/* We're already connected. Call the callback immediately. */
+		callback();
+	} else {
+		if (drv_mgmt->num_deferred_callbacks >= VCHIQ_DRV_MAX_CALLBACKS) {
+			dev_err(&device->dev,
+				"core: deferred callbacks(%d) exceeded the maximum limit(%d)\n",
+				drv_mgmt->num_deferred_callbacks, VCHIQ_DRV_MAX_CALLBACKS);
+		} else {
+			drv_mgmt->deferred_callback[drv_mgmt->num_deferred_callbacks] =
+				callback;
+			drv_mgmt->num_deferred_callbacks++;
+		}
+	}
+	mutex_unlock(&drv_mgmt->connected_mutex);
+}
+EXPORT_SYMBOL(vchiq_add_connected_callback);
+
 /* There is a potential problem with partial cache lines (pages?)
  * at the ends of the block when reading. If the CPU accessed anything in
  * the same line (page?) then it may have pulled old data into the cache,

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

@@ -23,6 +23,7 @@
 #define VCHIQ_DRV_MAX_CALLBACKS 10
 
 struct rpi_firmware;
+struct vchiq_device;
 
 enum USE_TYPE_E {
 	USE_TYPE_SERVICE,
@@ -132,6 +133,10 @@ vchiq_instance_get_trace(struct vchiq_instance *instance);
 extern void
 vchiq_instance_set_trace(struct vchiq_instance *instance, int trace);
 
+extern void
+vchiq_add_connected_callback(struct vchiq_device *device,
+			     void (*callback)(void));
+
 #if IS_ENABLED(CONFIG_VCHIQ_CDEV)
 
 extern void