firmware: arm_ffa: Split bus and driver into distinct modules

Make the FF-A bus on its own as a distinct module initialized at
subsys_initcall level when builtin.

Keep the FF-A driver core stack, together with any configured transport,
in a different module initialized as module_init level.

FF-A drivers initialization is now changed to module_init level.
Acked-by: Sebastian Ene <sebastianene@google.com>
Link: https://lore.kernel.org/r/20240515094028.1947976-2-sudeep.holla@arm.comSigned-off-by: Sudeep Holla <sudeep.holla@arm.com>

drivers/firmware/arm_ffa/Makefile

@@ -2,5 +2,7 @@
 ffa-bus-y = bus.o
 ffa-driver-y = driver.o
 ffa-transport-$(CONFIG_ARM_FFA_SMCCC) += smccc.o
-ffa-module-objs := $(ffa-bus-y) $(ffa-driver-y) $(ffa-transport-y)
-obj-$(CONFIG_ARM_FFA_TRANSPORT) = ffa-module.o
+ffa-core-objs := $(ffa-bus-y)
+ffa-module-objs := $(ffa-driver-y) $(ffa-transport-y)
+obj-$(CONFIG_ARM_FFA_TRANSPORT)  = ffa-core.o
+obj-$(CONFIG_ARM_FFA_TRANSPORT) += ffa-module.o

drivers/firmware/arm_ffa/bus.c

@@ -235,14 +235,21 @@ void ffa_device_unregister(struct ffa_device *ffa_dev)
 }
 EXPORT_SYMBOL_GPL(ffa_device_unregister);
 
-int arm_ffa_bus_init(void)
+static int __init arm_ffa_bus_init(void)
 {
 	return bus_register(&ffa_bus_type);
 }
+subsys_initcall(arm_ffa_bus_init);
 
-void arm_ffa_bus_exit(void)
+static void __exit arm_ffa_bus_exit(void)
 {
 	ffa_devices_unregister();
 	bus_unregister(&ffa_bus_type);
 	ida_destroy(&ffa_bus_id);
 }
+module_exit(arm_ffa_bus_exit);
+
+MODULE_ALIAS("ffa-core");
+MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
+MODULE_DESCRIPTION("ARM FF-A bus");
+MODULE_LICENSE("GPL");

drivers/firmware/arm_ffa/common.h

@@ -14,8 +14,6 @@ typedef struct arm_smccc_1_2_regs ffa_value_t;
 
 typedef void (ffa_fn)(ffa_value_t, ffa_value_t *);
 
-int arm_ffa_bus_init(void);
-void arm_ffa_bus_exit(void);
 bool ffa_device_is_valid(struct ffa_device *ffa_dev);
 void ffa_device_match_uuid(struct ffa_device *ffa_dev, const uuid_t *uuid);
 

drivers/firmware/arm_ffa/driver.c

@@ -1608,14 +1608,9 @@ static int __init ffa_init(void)
 	if (ret)
 		return ret;
 
-	ret = arm_ffa_bus_init();
-	if (ret)
-		return ret;
-
 	drv_info = kzalloc(sizeof(*drv_info), GFP_KERNEL);
 	if (!drv_info) {
-		ret = -ENOMEM;
-		goto ffa_bus_exit;
+		return -ENOMEM;
 	}
 
 	ret = ffa_version_check(&drv_info->version);
@@ -1676,11 +1671,9 @@ static int __init ffa_init(void)
 	free_pages_exact(drv_info->rx_buffer, RXTX_BUFFER_SIZE);
 free_drv_info:
 	kfree(drv_info);
-ffa_bus_exit:
-	arm_ffa_bus_exit();
 	return ret;
 }
-subsys_initcall(ffa_init);
+module_init(ffa_init);
 
 static void __exit ffa_exit(void)
 {
@@ -1690,7 +1683,6 @@ static void __exit ffa_exit(void)
 	free_pages_exact(drv_info->tx_buffer, RXTX_BUFFER_SIZE);
 	free_pages_exact(drv_info->rx_buffer, RXTX_BUFFER_SIZE);
 	kfree(drv_info);
-	arm_ffa_bus_exit();
 }
 module_exit(ffa_exit);