habanalabs: Add CB IOCTL opcode to retrieve CB information

Add a new CB IOCTL opcode that enables a user to query about a CB and
get its usage count.

Signed-off-by: Tomer Tayar <ttayar@habana.ai>
Reviewed-by: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Oded Gabbay <ogabbay@kernel.org>

include/uapi/misc/habanalabs.h

@@ -483,6 +483,8 @@ struct hl_info_args {
 #define HL_CB_OP_CREATE		0
 /* Opcode to destroy previously created command buffer */
 #define HL_CB_OP_DESTROY	1
+/* Opcode to retrieve information about a command buffer */
+#define HL_CB_OP_INFO		2
 
 /* 2MB minus 32 bytes for 2xMSG_PROT */
 #define HL_MAX_CB_SIZE		(0x200000 - 32)
@@ -506,8 +508,17 @@ struct hl_cb_in {
 };
 
 struct hl_cb_out {
-	/* Handle of CB */
-	__u64 cb_handle;
+	union {
+		/* Handle of CB */
+		__u64 cb_handle;
+
+		/* Information about CB */
+		struct {
+			/* Usage count of CB */
+			__u32 usage_cnt;
+			__u32 pad;
+		};
+	};
 };
 
 union hl_cb_args {