From patchwork Sat Oct 9 13:13:04 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vincent Mailhol X-Patchwork-Id: 12547689 X-Patchwork-Delegate: kuba@kernel.org Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6A03AC433FE for ; Sat, 9 Oct 2021 13:15:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4E9DC60F5A for ; Sat, 9 Oct 2021 13:15:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233652AbhJINRN (ORCPT ); Sat, 9 Oct 2021 09:17:13 -0400 Received: from smtp03.smtpout.orange.fr ([80.12.242.125]:57407 "EHLO smtp.smtpout.orange.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233661AbhJINPf (ORCPT ); Sat, 9 Oct 2021 09:15:35 -0400 Received: from tomoyo.flets-east.jp ([114.149.34.46]) by smtp.orange.fr with ESMTPA id ZC9zmoEn4UGqlZCARm2ihC; Sat, 09 Oct 2021 15:13:37 +0200 X-ME-Helo: tomoyo.flets-east.jp X-ME-Auth: MDU0YmViZGZmMDIzYiBlMiM2NTczNTRjNWZkZTMwOGRiOGQ4ODf3NWI1ZTMyMzdiODlhOQ== X-ME-Date: Sat, 09 Oct 2021 15:13:37 +0200 X-ME-IP: 114.149.34.46 From: Vincent Mailhol To: Marc Kleine-Budde , linux-can@vger.kernel.org Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Vincent Mailhol Subject: [PATCH v2 3/3] can: netlink: report the CAN controller mode supported flags Date: Sat, 9 Oct 2021 22:13:04 +0900 Message-Id: <20211009131304.19729-4-mailhol.vincent@wanadoo.fr> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20211009131304.19729-1-mailhol.vincent@wanadoo.fr> References: <20211009131304.19729-1-mailhol.vincent@wanadoo.fr> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org This patch introduces a method for the user to check both the supported and the static capabilities. The proposed method reuses the existing struct can_ctrlmode and thus do not need a new IFLA_CAN_* entry. 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...) It appears that, can_ctrlmode::mask is only used in one direction: from the userland to the kernel. So we can just reuse this field in the other direction (from the kernel to userland). But, because the semantic is different, we use a union to give this field a proper name: supported. Below table explains how the two fields can_ctrlmode::supported and can_ctrlmode::flags, when masked with any of the CAN_CTRLMODE_* bit flags, allow us to identify both the supported and the static capabilities: 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 Signed-off-by: Vincent Mailhol --- Please refer to below link for the iproute2-next counterpart of this patch: https://lore.kernel.org/linux-can/20211003050147.569044-1-mailhol.vincent@wanadoo.fr/T/#t --- drivers/net/can/dev/netlink.c | 5 ++++- include/uapi/linux/can/netlink.h | 5 ++++- 2 files changed, 8 insertions(+), 2 deletions(-) diff --git a/drivers/net/can/dev/netlink.c b/drivers/net/can/dev/netlink.c index 6c9906e8040c..86521836fd6d 100644 --- a/drivers/net/can/dev/netlink.c +++ b/drivers/net/can/dev/netlink.c @@ -264,7 +264,10 @@ static size_t can_get_size(const struct net_device *dev) static int can_fill_info(struct sk_buff *skb, const struct net_device *dev) { struct can_priv *priv = netdev_priv(dev); - struct can_ctrlmode cm = {.flags = priv->ctrlmode}; + struct can_ctrlmode cm = { + .supported = priv->ctrlmode_supported, + .flags = priv->ctrlmode + }; struct can_berr_counter bec = { }; enum can_state state = priv->state; diff --git a/include/uapi/linux/can/netlink.h b/include/uapi/linux/can/netlink.h index f730d443b918..2847ed0dcac3 100644 --- a/include/uapi/linux/can/netlink.h +++ b/include/uapi/linux/can/netlink.h @@ -88,7 +88,10 @@ struct can_berr_counter { * CAN controller mode */ struct can_ctrlmode { - __u32 mask; + union { + __u32 mask; /* Userland to kernel */ + __u32 supported; /* Kernel to userland */ + }; __u32 flags; };