Add API functions for registering and removing a notifier for FPGA
manager register/unregister events. Notify when a new FPGA manager
has been registered or when an existing manager is being removed.
This will help configuration interface drivers to get the notion
of low-level FPGA managers appearing or disappearing, when using
hotpluggable FPGA configuration devices (e.g. via USB-FPP or
USB-SPI adapters).
Signed-off-by: Anatolij Gustschin <agust@xxxxxxx>
---
Changes in v2:
- rebased on v4.20-rc1, reworked documentation
- also notify about all fpga managers that were registered before
adding the manager register/unregister notifier
Documentation/driver-api/fpga/fpga-mgr.rst | 15 ++++++++
drivers/fpga/fpga-mgr.c | 45 ++++++++++++++++++++++
include/linux/fpga/fpga-mgr.h | 12 ++++++
3 files changed, 72 insertions(+)
diff --git a/Documentation/driver-api/fpga/fpga-mgr.rst b/Documentation/driver-api/fpga/fpga-mgr.rst
index 576f1945eacd..fd736a22f5fc 100644
--- a/Documentation/driver-api/fpga/fpga-mgr.rst
+++ b/Documentation/driver-api/fpga/fpga-mgr.rst
@@ -125,3 +125,18 @@ API for implementing a new FPGA Manager driver
.. kernel-doc:: drivers/fpga/fpga-mgr.c
:functions: fpga_mgr_unregister
+
+Notification about added or removed FPGA managers
+-------------------------------------------------
+
+To register or unregister the notifier callback for signalling
+about the low level FPGA managers being added or removed, use
+
+* :c:func:`fpga_mgr_register_mgr_notifier` — Add notifier for manager add/remove event
+* :c:func:`fpga_mgr_unregister_mgr_notifier` — Remove notifier for manager events
+
+.. kernel-doc:: drivers/fpga/fpga-mgr.c
+ :functions: fpga_mgr_register_mgr_notifier
+
+.. kernel-doc:: drivers/fpga/fpga-mgr.c
+ :functions: fpga_mgr_unregister_mgr_notifier
diff --git a/drivers/fpga/fpga-mgr.c b/drivers/fpga/fpga-mgr.c
index c3866816456a..307717ad9c6d 100644
--- a/drivers/fpga/fpga-mgr.c
+++ b/drivers/fpga/fpga-mgr.c
@@ -21,6 +21,46 @@
static DEFINE_IDA(fpga_mgr_ida);
static struct class *fpga_mgr_class;
+static BLOCKING_NOTIFIER_HEAD(fpga_mgr_notifier_list);
+
+static int fpga_mgr_notify_registered(struct device *dev, void *data)
+{
+ struct fpga_manager *mgr = to_fpga_manager(dev);
+
+ blocking_notifier_call_chain(&fpga_mgr_notifier_list,
+ FPGA_MGR_ADD, mgr);
+ return 0;
+}
+
+/**
+ * fpga_mgr_register_mgr_notifier() - register fpga manager notifier callback
+ * @nb: pointer to the notifier block for the callback events.
+ *
+ * Add a notifier callback for FPGA manager changes. These changes are
+ * either FPGA manager being added or removed.
+ */
+void fpga_mgr_register_mgr_notifier(struct notifier_block *nb)
+{
+ blocking_notifier_chain_register(&fpga_mgr_notifier_list, nb);
+
+ class_for_each_device(fpga_mgr_class, NULL, NULL,
+ fpga_mgr_notify_registered);
+}
+EXPORT_SYMBOL_GPL(fpga_mgr_register_mgr_notifier);
+
+/**
+ * fpga_mgr_unregister_mgr_notifier() - unregister a notifier callback
+ * @nb: pointer to the notifier block for the callback events.
+ *
+ * Remove a notifier callback. fpga_mgr_register_mgr_notifier() must have
+ * been previously called for this function to work properly.
+ */
+void fpga_mgr_unregister_mgr_notifier(struct notifier_block *nb)
+{
+ blocking_notifier_chain_unregister(&fpga_mgr_notifier_list, nb);
+}
+EXPORT_SYMBOL_GPL(fpga_mgr_unregister_mgr_notifier);
+
/**
* fpga_image_info_alloc - Allocate a FPGA image info struct
* @dev: owning device
@@ -700,6 +740,8 @@ int fpga_mgr_register(struct fpga_manager *mgr)
dev_info(&mgr->dev, "%s registered\n", mgr->name);
+ blocking_notifier_call_chain(&fpga_mgr_notifier_list,
+ FPGA_MGR_ADD, mgr);
return 0;
error_device:
@@ -719,6 +761,9 @@ void fpga_mgr_unregister(struct fpga_manager *mgr)
{
dev_info(&mgr->dev, "%s %s\n", __func__, mgr->name);
+ blocking_notifier_call_chain(&fpga_mgr_notifier_list,
+ FPGA_MGR_REMOVE, mgr);
+
/*
* If the low level driver provides a method for putting fpga into
* a desired state upon unregister, do it.
diff --git a/include/linux/fpga/fpga-mgr.h b/include/linux/fpga/fpga-mgr.h
index e8ca62b2cb5b..d6eaec80557b 100644
--- a/include/linux/fpga/fpga-mgr.h
+++ b/include/linux/fpga/fpga-mgr.h
@@ -10,6 +10,7 @@
#include <linux/mutex.h>
#include <linux/platform_device.h>
+#include <linux/notifier.h>
struct fpga_manager;
struct sg_table;
@@ -202,4 +203,15 @@ struct fpga_manager *devm_fpga_mgr_create(struct device *dev, const char *name,
const struct fpga_manager_ops *mops,
void *priv);
+/*
+ * FPGA Manager register notifier events
+ * FPGA_MGR_ADD: a new fpga manager has been registered
+ * FPGA_MGR_REMOVE: a registered fpga manager is being removed
+ */
+#define FPGA_MGR_ADD 1
+#define FPGA_MGR_REMOVE 2
+
+void fpga_mgr_register_mgr_notifier(struct notifier_block *nb);
+void fpga_mgr_unregister_mgr_notifier(struct notifier_block *nb);
+
#endif /*_LINUX_FPGA_MGR_H */
--
2.17.1
