From 383f0993fc77152b0773c85ed69d6734baf9cb48 Mon Sep 17 00:00:00 2001 From: Vincent Mailhol Date: Tue, 14 Dec 2021 01:02:26 +0900 Subject: can: netlink: report the CAN controller mode supported flags Currently, the CAN netlink interface provides no easy ways to check the capabilities of a given controller. The only method from the command line is to try each CAN_CTRLMODE_* individually to check whether the netlink interface returns an -EOPNOTSUPP error or not (alternatively, one may find it easier to directly check the source code of the driver instead...) This patch introduces a method for the user to check both the supported and the static capabilities. The proposed method introduces a new IFLA nest: IFLA_CAN_CTRLMODE_EXT which extends the current IFLA_CAN_CTRLMODE. This is done to guaranty a full forward and backward compatibility between the kernel and the user land applications. The IFLA_CAN_CTRLMODE_EXT nest contains one single entry: IFLA_CAN_CTRLMODE_SUPPORTED. Because this entry is only used in one direction: kernel to userland, no new struct nla_policy are introduced. Below table explains how IFLA_CAN_CTRLMODE_SUPPORTED (hereafter: "supported") and can_ctrlmode::flags (hereafter: "flags") allow us to identify both the supported and the static capabilities, when masked with any of the CAN_CTRLMODE_* bit flags: supported & flags & Controller capabilities CAN_CTRLMODE_* CAN_CTRLMODE_* ----------------------------------------------------------------------- false false Feature not supported (always disabled) false true Static feature (always enabled) true false Feature supported but disabled true true Feature supported and enabled Link: https://lore.kernel.org/all/20211213160226.56219-5-mailhol.vincent@wanadoo.fr Signed-off-by: Vincent Mailhol Signed-off-by: Marc Kleine-Budde --- include/uapi/linux/can/netlink.h | 13 +++++++++++++ 1 file changed, 13 insertions(+) (limited to 'include/uapi/linux/can/netlink.h') diff --git a/include/uapi/linux/can/netlink.h b/include/uapi/linux/can/netlink.h index 75b85c60efb2..02ec32d69474 100644 --- a/include/uapi/linux/can/netlink.h +++ b/include/uapi/linux/can/netlink.h @@ -137,6 +137,7 @@ enum { IFLA_CAN_DATA_BITRATE_CONST, IFLA_CAN_BITRATE_MAX, IFLA_CAN_TDC, + IFLA_CAN_CTRLMODE_EXT, /* add new constants above here */ __IFLA_CAN_MAX, @@ -166,6 +167,18 @@ enum { IFLA_CAN_TDC_MAX = __IFLA_CAN_TDC - 1 }; +/* + * IFLA_CAN_CTRLMODE_EXT nest: controller mode extended parameters + */ +enum { + IFLA_CAN_CTRLMODE_UNSPEC, + IFLA_CAN_CTRLMODE_SUPPORTED, /* u32 */ + + /* add new constants above here */ + __IFLA_CAN_CTRLMODE, + IFLA_CAN_CTRLMODE_MAX = __IFLA_CAN_CTRLMODE - 1 +}; + /* u16 termination range: 1..65535 Ohms */ #define CAN_TERMINATION_DISABLED 0 -- cgit v1.2.3