Merge tag 'ffa-updates-6.11' of git://git.kernel.org/pub/scm/linux/kernel/git/sudeep.holla/linux into soc/drivers

Arm FF-A driver updates for  v6.11

The main addition is the split of bus and driver into distinct modules
The FF-A bus module is initialized at subsys_initcall level when builtin.

FF-A drivers initialization is now changed to module_init level so that
pKVM ffa proxy is all setup and running in case pKVM hypervisor needs to
trap and handle FF-A calls.

One of the reason for not having this split from the beginning is the
need to workaround the FF-A v1.0 NULL UUID. The FF-A bus layer called
into FF-A driver and populated the device UUID if it matches with the
driver attempting to match. Moving the workaround away from the FF-A
bus layer to the FF-A core driver as a bus notifier will help to remove
the dependency.

* tag 'ffa-updates-6.11' of git://git.kernel.org/pub/scm/linux/kernel/git/sudeep.holla/linux:
  firmware: arm_ffa: Split bus and driver into distinct modules
  firmware: arm_ffa: Move the FF-A v1.0 NULL UUID workaround to bus notifier

Link: https://lore.kernel.org/r/20240624103451.2870146-1-sudeep.holla@arm.com
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

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

@@ -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@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

@@ -1224,14 +1224,6 @@ void ffa_device_match_uuid(struct ffa_device *ffa_dev, const uuid_t *uuid)
 	int count, idx;
 	struct ffa_partition_info *pbuf, *tpbuf;
 
-	/*
-	 * FF-A v1.1 provides UUID for each partition as part of the discovery
-	 * API, the discovered UUID must be populated in the device's UUID and
-	 * there is no need to copy the same from the driver table.
-	 */
-	if (drv_info->version > FFA_VERSION_1_0)
-		return;
-
 	count = ffa_partition_probe(uuid, &pbuf);
 	if (count <= 0)
 		return;
@@ -1242,6 +1234,35 @@ void ffa_device_match_uuid(struct ffa_device *ffa_dev, const uuid_t *uuid)
 	kfree(pbuf);
 }
 
+static int
+ffa_bus_notifier(struct notifier_block *nb, unsigned long action, void *data)
+{
+	struct device *dev = data;
+	struct ffa_device *fdev = to_ffa_dev(dev);
+
+	if (action == BUS_NOTIFY_BIND_DRIVER) {
+		struct ffa_driver *ffa_drv = to_ffa_driver(dev->driver);
+		const struct ffa_device_id *id_table= ffa_drv->id_table;
+
+		/*
+		 * FF-A v1.1 provides UUID for each partition as part of the
+		 * discovery API, the discovered UUID must be populated in the
+		 * device's UUID and there is no need to workaround by copying
+		 * the same from the driver table.
+		 */
+		if (uuid_is_null(&fdev->uuid))
+			ffa_device_match_uuid(fdev, &id_table->uuid);
+
+		return NOTIFY_OK;
+	}
+
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block ffa_bus_nb = {
+	.notifier_call = ffa_bus_notifier,
+};
+
 static int ffa_setup_partitions(void)
 {
 	int count, idx, ret;
@@ -1250,6 +1271,12 @@ static int ffa_setup_partitions(void)
 	struct ffa_dev_part_info *info;
 	struct ffa_partition_info *pbuf, *tpbuf;
 
+	if (drv_info->version == FFA_VERSION_1_0) {
+		ret = bus_register_notifier(&ffa_bus_type, &ffa_bus_nb);
+		if (ret)
+			pr_err("Failed to register FF-A bus notifiers\n");
+	}
+
 	count = ffa_partition_probe(&uuid_null, &pbuf);
 	if (count <= 0) {
 		pr_info("%s: No partitions found, error %d\n", __func__, count);
@@ -1261,7 +1288,7 @@ static int ffa_setup_partitions(void)
 		import_uuid(&uuid, (u8 *)tpbuf->uuid);
 
 		/* Note that if the UUID will be uuid_null, that will require
-		 * ffa_device_match() to find the UUID of this partition id
+		 * ffa_bus_notifier() to find the UUID of this partition id
 		 * with help of ffa_device_match_uuid(). FF-A v1.1 and above
 		 * provides UUID here for each partition as part of the
 		 * discovery API and the same is passed.
@@ -1581,14 +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);
@@ -1649,11 +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)
 {
@@ -1663,7 +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);