[RFC 4/5] drm/netlink: Define multicast groups

[Aravind Iddamsetty <aravind.iddamsetty@xxxxxxxxxxxxxxx>]

Netlink subsystem supports event notifications to userspace. we define
two multicast groups for correctable and uncorrectable errors to which
userspace can subscribe and be notified when any of those errors happen.
The group names are local to the driver's genl netlink family.

Signed-off-by: Aravind Iddamsetty <aravind.iddamsetty@xxxxxxxxxxxxxxx>
---
 drivers/gpu/drm/drm_netlink.c  | 7 +++++++
 include/drm/drm_netlink.h      | 5 +++++
 include/uapi/drm/drm_netlink.h | 4 ++++
 3 files changed, 16 insertions(+)

diff --git a/drivers/gpu/drm/drm_netlink.c b/drivers/gpu/drm/drm_netlink.c
index 8add249c1da3..425a7355a573 100644
--- a/drivers/gpu/drm/drm_netlink.c
+++ b/drivers/gpu/drm/drm_netlink.c
@@ -12,6 +12,11 @@
 
 DEFINE_XARRAY(drm_dev_xarray);
 
+static const struct genl_multicast_group drm_event_mcgrps[] = {
+	[DRM_GENL_MCAST_CORR_ERR] = { .name = DRM_GENL_MCAST_GROUP_NAME_CORR_ERR, },
+	[DRM_GENL_MCAST_UNCORR_ERR] = { .name = DRM_GENL_MCAST_GROUP_NAME_UNCORR_ERR, },
+};
+
 /**
  * drm_genl_reply - response to a request
  * @msg: socket buffer
@@ -133,6 +138,8 @@ static void drm_genl_family_init(struct drm_device *dev)
 	dev->drm_genl_family.ops = drm_genl_ops;
 	dev->drm_genl_family.n_ops = ARRAY_SIZE(drm_genl_ops);
 	dev->drm_genl_family.maxattr = DRM_ATTR_MAX;
+	dev->drm_genl_family.mcgrps = drm_event_mcgrps;
+	dev->drm_genl_family.n_mcgrps = ARRAY_SIZE(drm_event_mcgrps);
 	dev->drm_genl_family.module = dev->dev->driver->owner;
 }
 
diff --git a/include/drm/drm_netlink.h b/include/drm/drm_netlink.h
index 54527dae7847..758239643c17 100644
--- a/include/drm/drm_netlink.h
+++ b/include/drm/drm_netlink.h
@@ -13,6 +13,11 @@
 
 struct drm_device;
 
+enum mcgrps_events {
+	DRM_GENL_MCAST_CORR_ERR,
+	DRM_GENL_MCAST_UNCORR_ERR,
+};
+
 struct driver_genl_ops {
 	int		       (*doit)(struct drm_device *dev,
 				       struct sk_buff *skb,
diff --git a/include/uapi/drm/drm_netlink.h b/include/uapi/drm/drm_netlink.h
index aab42147a20e..c7a0ce5b4624 100644
--- a/include/uapi/drm/drm_netlink.h
+++ b/include/uapi/drm/drm_netlink.h
@@ -26,6 +26,8 @@
 #define _DRM_NETLINK_H_
 
 #define DRM_GENL_VERSION 1
+#define DRM_GENL_MCAST_GROUP_NAME_CORR_ERR	"drm_corr_err"
+#define DRM_GENL_MCAST_GROUP_NAME_UNCORR_ERR	"drm_uncorr_err"
 
 #if defined(__cplusplus)
 extern "C" {
@@ -43,6 +45,8 @@ enum drm_genl_error_cmds {
 	DRM_RAS_CMD_READ_ONE,
 	/** @DRM_RAS_CMD_READ_ALL: Command to get counters of all errors */
 	DRM_RAS_CMD_READ_ALL,
+	/** @DRM_RAS_CMD_ERROR_EVENT: Command sent as part of multicast event */
+	DRM_RAS_CMD_ERROR_EVENT,
 
 	__DRM_CMD_MAX,
 	DRM_CMD_MAX = __DRM_CMD_MAX - 1,
-- 
2.25.1