[PATCH v6 2/8] vfio: platform: add capability to register a reset function

[Eric Auger]

In preparation for subsequent changes in reset function lookup,
lets introduce a dynamic list of reset combos (compat string,
reset module, reset function). The list can be populated/voided with
vfio_platform_register/unregister_reset. Those are not yet used in
this patch.

Signed-off-by: Eric Auger <eric.auger at linaro.org>
Reviewed-by: Arnd Bergmann <arnd at arndb.de>

---

v4 -> v5:
- add Arnd's R-b

v3 -> v4:
- __vfio_platform_register_reset does not return any value anymore
- vfio_platform_unregister_reset also takes the reset function pointer
  as parameter

v2 -> v3:
- use goto out to have a single mutex_unlock
- implement vfio_platform_register_reset as a macro (suggested by Arnd)
- move reset_node struct declaration back to vfio_platform_private.h
- vfio_platform_unregister_reset does not return any value anymore

v1 -> v2:
- reset_list becomes static
- vfio_platform_register/unregister_reset take a const char * as compat
- fix node leak
- add reset_lock to protect the reset list manipulation
- move vfio_platform_reset_node declaration in vfio_platform_common.c
---
 drivers/vfio/platform/vfio_platform_common.c  | 27 +++++++++++++++++++++++++++
 drivers/vfio/platform/vfio_platform_private.h | 20 ++++++++++++++++++++
 2 files changed, 47 insertions(+)

diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
index 184e9d2..3b7e52c 100644
--- a/drivers/vfio/platform/vfio_platform_common.c
+++ b/drivers/vfio/platform/vfio_platform_common.c
@@ -27,6 +27,7 @@
 #define DRIVER_AUTHOR   "Antonios Motakis <a.motakis at virtualopensystems.com>"
 #define DRIVER_DESC     "VFIO platform base module"
 
+static LIST_HEAD(reset_list);
 static DEFINE_MUTEX(driver_lock);
 
 static const struct vfio_platform_reset_combo reset_lookup_table[] = {
@@ -578,6 +579,32 @@ struct vfio_platform_device *vfio_platform_remove_common(struct device *dev)
 }
 EXPORT_SYMBOL_GPL(vfio_platform_remove_common);
 
+void __vfio_platform_register_reset(struct vfio_platform_reset_node *node)
+{
+	mutex_lock(&driver_lock);
+	list_add(&node->link, &reset_list);
+	mutex_unlock(&driver_lock);
+}
+EXPORT_SYMBOL_GPL(__vfio_platform_register_reset);
+
+void vfio_platform_unregister_reset(const char *compat,
+				    vfio_platform_reset_fn_t fn)
+{
+	struct vfio_platform_reset_node *iter, *temp;
+
+	mutex_lock(&driver_lock);
+	list_for_each_entry_safe(iter, temp, &reset_list, link) {
+		if (!strcmp(iter->compat, compat) && (iter->reset == fn)) {
+			list_del(&iter->link);
+			break;
+		}
+	}
+
+	mutex_unlock(&driver_lock);
+
+}
+EXPORT_SYMBOL_GPL(vfio_platform_unregister_reset);
+
 MODULE_VERSION(DRIVER_VERSION);
 MODULE_LICENSE("GPL v2");
 MODULE_AUTHOR(DRIVER_AUTHOR);
diff --git a/drivers/vfio/platform/vfio_platform_private.h b/drivers/vfio/platform/vfio_platform_private.h
index 7128690..c563940 100644
--- a/drivers/vfio/platform/vfio_platform_private.h
+++ b/drivers/vfio/platform/vfio_platform_private.h
@@ -71,6 +71,15 @@ struct vfio_platform_device {
 	int	(*reset)(struct vfio_platform_device *vdev);
 };
 
+typedef int (*vfio_platform_reset_fn_t)(struct vfio_platform_device *vdev);
+
+struct vfio_platform_reset_node {
+	struct list_head link;
+	char *compat;
+	struct module *owner;
+	vfio_platform_reset_fn_t reset;
+};
+
 struct vfio_platform_reset_combo {
 	const char *compat;
 	const char *reset_function_name;
@@ -90,4 +99,15 @@ extern int vfio_platform_set_irqs_ioctl(struct vfio_platform_device *vdev,
 					unsigned start, unsigned count,
 					void *data);
 
+extern void __vfio_platform_register_reset(struct vfio_platform_reset_node *n);
+extern void vfio_platform_unregister_reset(const char *compat,
+					   vfio_platform_reset_fn_t fn);
+#define vfio_platform_register_reset(__compat, __reset)		\
+static struct vfio_platform_reset_node __reset ## _node = {	\
+	.owner = THIS_MODULE,					\
+	.compat = __compat,					\
+	.reset = __reset,					\
+};								\
+__vfio_platform_register_reset(&__reset ## _node)
+
 #endif /* VFIO_PLATFORM_PRIVATE_H */
-- 
1.9.1