[RFC net-next v2 1/6] ethtool: Add loopback netlink UAPI definitions

["Björn Töpel" <bjorn@kernel.org>]

Add the netlink YAML spec and auto-generated UAPI header for a unified
loopback interface covering MAC, PCS, PHY, and pluggable module
components.

Each loopback point is described by a nested entry attribute
containing:

 - component  where in the path (MAC, PCS, PHY, MODULE)
 - name       subsystem label, e.g. "cmis-host" or "cmis-media"
 - id         optional instance selector (e.g. PHY id, port id)
 - supported  bitmask of supported directions
 - direction  NEAR_END, FAR_END, or 0 (disabled)

Signed-off-by: Björn Töpel <bjorn@kernel.org>
---
 Documentation/netlink/specs/ethtool.yaml      | 115 ++++++++++++++++++
 .../uapi/linux/ethtool_netlink_generated.h    |  52 ++++++++
 2 files changed, 167 insertions(+)

diff --git a/Documentation/netlink/specs/ethtool.yaml b/Documentation/netlink/specs/ethtool.yaml
index 4707063af3b4..05ebad6ae4e0 100644
--- a/Documentation/netlink/specs/ethtool.yaml
+++ b/Documentation/netlink/specs/ethtool.yaml
@@ -211,6 +211,39 @@ definitions:
         name: discard
         value: 31
 
+  -
+    name: loopback-component
+    type: enum
+    doc: |
+      Loopback component. Identifies where in the network path the
+      loopback is applied.
+    entries:
+      -
+        name: mac
+        doc: MAC loopback
+      -
+        name: pcs
+        doc: PCS loopback
+      -
+        name: phy
+        doc: PHY loopback
+      -
+        name: module
+        doc: Pluggable module (e.g. CMIS (Q)SFP) loopback
+  -
+    name: loopback-direction
+    type: flags
+    doc: |
+      Loopback direction flags. Used as a bitmask in supported, and as
+      a single value in direction.
+    entries:
+      -
+        name: near-end
+        doc: Near-end loopback; host-loop-host
+      -
+        name: far-end
+        doc: Far-end loopback; line-loop-line
+
 attribute-sets:
   -
     name: header
@@ -1903,6 +1936,60 @@ attribute-sets:
         name: link
         type: nest
         nested-attributes: mse-snapshot
+  -
+    name: loopback-entry
+    doc: Per-component loopback configuration entry.
+    attr-cnt-name: __ethtool-a-loopback-entry-cnt
+    attributes:
+      -
+        name: unspec
+        type: unused
+        value: 0
+      -
+        name: component
+        type: u32
+        enum: loopback-component
+        doc: Loopback component
+      -
+        name: id
+        type: u32
+        doc: |
+          Optional component instance identifier. Required for PHY,
+          optional for MODULE, omitted for MAC and PCS.
+      -
+        name: name
+        type: string
+        doc: |
+          Subsystem-specific name for the loopback point within the
+          component.
+      -
+        name: supported
+        type: u32
+        enum: loopback-direction
+        enum-as-flags: true
+        doc: Bitmask of supported loopback directions
+      -
+        name: direction
+        type: u32
+        enum: loopback-direction
+        doc: Current loopback direction, 0 means disabled
+  -
+    name: loopback
+    attr-cnt-name: __ethtool-a-loopback-cnt
+    attributes:
+      -
+        name: unspec
+        type: unused
+        value: 0
+      -
+        name: header
+        type: nest
+        nested-attributes: header
+      -
+        name: entry
+        type: nest
+        multi-attr: true
+        nested-attributes: loopback-entry
 
 operations:
   enum-model: directional
@@ -2855,6 +2942,34 @@ operations:
             - worst-channel
             - link
       dump: *mse-get-op
+    -
+      name: loopback-get
+      doc: Get loopback configuration and capabilities.
+
+      attribute-set: loopback
+
+      do: &loopback-get-op
+        request:
+          attributes:
+            - header
+        reply:
+          attributes: &loopback
+            - header
+            - entry
+      dump: *loopback-get-op
+    -
+      name: loopback-set
+      doc: Set loopback configuration.
+
+      attribute-set: loopback
+
+      do:
+        request:
+          attributes: *loopback
+    -
+      name: loopback-ntf
+      doc: Notification for change in loopback configuration.
+      notify: loopback-get
 
 mcast-groups:
   list:
diff --git a/include/uapi/linux/ethtool_netlink_generated.h b/include/uapi/linux/ethtool_netlink_generated.h
index 114b83017297..83fb17dd5daf 100644
--- a/include/uapi/linux/ethtool_netlink_generated.h
+++ b/include/uapi/linux/ethtool_netlink_generated.h
@@ -78,6 +78,33 @@ enum ethtool_pse_event {
 	ETHTOOL_PSE_EVENT_SW_PW_CONTROL_ERROR = 64,
 };
 
+/**
+ * enum ethtool_loopback_component - Loopback component. Identifies where in
+ *   the network path the loopback is applied.
+ * @ETHTOOL_LOOPBACK_COMPONENT_MAC: MAC loopback
+ * @ETHTOOL_LOOPBACK_COMPONENT_PCS: PCS loopback
+ * @ETHTOOL_LOOPBACK_COMPONENT_PHY: PHY loopback
+ * @ETHTOOL_LOOPBACK_COMPONENT_MODULE: Pluggable module (e.g. CMIS (Q)SFP)
+ *   loopback
+ */
+enum ethtool_loopback_component {
+	ETHTOOL_LOOPBACK_COMPONENT_MAC,
+	ETHTOOL_LOOPBACK_COMPONENT_PCS,
+	ETHTOOL_LOOPBACK_COMPONENT_PHY,
+	ETHTOOL_LOOPBACK_COMPONENT_MODULE,
+};
+
+/**
+ * enum ethtool_loopback_direction - Loopback direction flags. Used as a
+ *   bitmask in supported, and as a single value in direction.
+ * @ETHTOOL_LOOPBACK_DIRECTION_NEAR_END: Near-end loopback; host-loop-host
+ * @ETHTOOL_LOOPBACK_DIRECTION_FAR_END: Far-end loopback; line-loop-line
+ */
+enum ethtool_loopback_direction {
+	ETHTOOL_LOOPBACK_DIRECTION_NEAR_END = 1,
+	ETHTOOL_LOOPBACK_DIRECTION_FAR_END = 2,
+};
+
 enum {
 	ETHTOOL_A_HEADER_UNSPEC,
 	ETHTOOL_A_HEADER_DEV_INDEX,
@@ -838,6 +865,27 @@ enum {
 	ETHTOOL_A_MSE_MAX = (__ETHTOOL_A_MSE_CNT - 1)
 };
 
+enum {
+	ETHTOOL_A_LOOPBACK_ENTRY_UNSPEC,
+	ETHTOOL_A_LOOPBACK_ENTRY_COMPONENT,
+	ETHTOOL_A_LOOPBACK_ENTRY_ID,
+	ETHTOOL_A_LOOPBACK_ENTRY_NAME,
+	ETHTOOL_A_LOOPBACK_ENTRY_SUPPORTED,
+	ETHTOOL_A_LOOPBACK_ENTRY_DIRECTION,
+
+	__ETHTOOL_A_LOOPBACK_ENTRY_CNT,
+	ETHTOOL_A_LOOPBACK_ENTRY_MAX = (__ETHTOOL_A_LOOPBACK_ENTRY_CNT - 1)
+};
+
+enum {
+	ETHTOOL_A_LOOPBACK_UNSPEC,
+	ETHTOOL_A_LOOPBACK_HEADER,
+	ETHTOOL_A_LOOPBACK_ENTRY,
+
+	__ETHTOOL_A_LOOPBACK_CNT,
+	ETHTOOL_A_LOOPBACK_MAX = (__ETHTOOL_A_LOOPBACK_CNT - 1)
+};
+
 enum {
 	ETHTOOL_MSG_USER_NONE = 0,
 	ETHTOOL_MSG_STRSET_GET = 1,
@@ -891,6 +939,8 @@ enum {
 	ETHTOOL_MSG_RSS_CREATE_ACT,
 	ETHTOOL_MSG_RSS_DELETE_ACT,
 	ETHTOOL_MSG_MSE_GET,
+	ETHTOOL_MSG_LOOPBACK_GET,
+	ETHTOOL_MSG_LOOPBACK_SET,
 
 	__ETHTOOL_MSG_USER_CNT,
 	ETHTOOL_MSG_USER_MAX = (__ETHTOOL_MSG_USER_CNT - 1)
@@ -952,6 +1002,8 @@ enum {
 	ETHTOOL_MSG_RSS_CREATE_NTF,
 	ETHTOOL_MSG_RSS_DELETE_NTF,
 	ETHTOOL_MSG_MSE_GET_REPLY,
+	ETHTOOL_MSG_LOOPBACK_GET_REPLY,
+	ETHTOOL_MSG_LOOPBACK_NTF,
 
 	__ETHTOOL_MSG_KERNEL_CNT,
 	ETHTOOL_MSG_KERNEL_MAX = (__ETHTOOL_MSG_KERNEL_CNT - 1)
-- 
2.53.0