[PATCH 2/2] firmware: arm_ffa: Split bus and driver into distinct modules

[Sudeep Holla]

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.

Signed-off-by: Sudeep Holla <sudeep.holla at arm.com>
---
 drivers/firmware/arm_ffa/Makefile |  6 ++++--
 drivers/firmware/arm_ffa/bus.c    | 22 ++++++++++++++++------
 drivers/firmware/arm_ffa/common.h |  2 --
 drivers/firmware/arm_ffa/driver.c | 12 ++----------
 4 files changed, 22 insertions(+), 20 deletions(-)

Hi Sebastian,

I reworked the patch I shared with you in private to include handling of
the FF-A v1.0 workaround I had removed as a quick hack when I shared the
patch. Please check if these couple of patches help you in the initcall
order issue you were facing.

Regards,
Sudeep

diff --git a/drivers/firmware/arm_ffa/Makefile b/drivers/firmware/arm_ffa/Makefile
index 9d9f37523200..168990a7e792 100644
--- a/drivers/firmware/arm_ffa/Makefile
+++ b/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
diff --git a/drivers/firmware/arm_ffa/bus.c b/drivers/firmware/arm_ffa/bus.c
index 2f557e90f2eb..0c83931485f6 100644
--- a/drivers/firmware/arm_ffa/bus.c
+++ b/drivers/firmware/arm_ffa/bus.c
@@ -30,12 +30,11 @@ static int ffa_device_match(struct device *dev, struct device_driver *drv)
 	while (!uuid_is_null(&id_table->uuid)) {
 		/*
 		 * FF-A v1.0 doesn't provide discovery of UUIDs, just the
-		 * partition IDs, so fetch the partitions IDs for this
-		 * id_table UUID and assign the UUID to the device if the
-		 * partition ID matches
+		 * partition IDs, so match it unconditionally here and handle
+		 * it via the installed bus notifier during driver binding.
 		 */
 		if (uuid_is_null(&ffa_dev->uuid))
-			ffa_device_match_uuid(ffa_dev, &id_table->uuid);
+			return 1;

 		if (uuid_equal(&ffa_dev->uuid, &id_table->uuid))
 			return 1;
@@ -50,6 +49,10 @@ static int ffa_device_probe(struct device *dev)
 	struct ffa_driver *ffa_drv = to_ffa_driver(dev->driver);
 	struct ffa_device *ffa_dev = to_ffa_dev(dev);

+	/* UUID can be still NULL with FF-A v1.0, so just skip probing them */
+	if (uuid_is_null(&ffa_dev->uuid))
+		return -ENODEV;
+
 	return ffa_drv->probe(ffa_dev);
 }

@@ -232,14 +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 at arm.com>");
+MODULE_DESCRIPTION("ARM FF-A bus");
+MODULE_LICENSE("GPL");
diff --git a/drivers/firmware/arm_ffa/common.h b/drivers/firmware/arm_ffa/common.h
index d6eccf1fd3f6..9c6425a81d0d 100644
--- a/drivers/firmware/arm_ffa/common.h
+++ b/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);

diff --git a/drivers/firmware/arm_ffa/driver.c b/drivers/firmware/arm_ffa/driver.c
index 159f2106a541..7cdd425c5fc4 100644
--- a/drivers/firmware/arm_ffa/driver.c
+++ b/drivers/firmware/arm_ffa/driver.c
@@ -1603,14 +1603,9 @@ 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);
@@ -1671,11 +1666,9 @@ 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)
 {
@@ -1685,7 +1678,6 @@ 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);

--
2.43.2