linux-kernel - [RFC PATCH v3 6/9] can: slcan: add support for listen-only mode

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Message-Id: <20220726210217.3368497-7-dario.binacchi@amarulasolutions.com>
Date:   Tue, 26 Jul 2022 23:02:14 +0200
From:   Dario Binacchi <dario.binacchi@...rulasolutions.com>
To:     linux-kernel@...r.kernel.org
Cc:     linux-can@...r.kernel.org, Marc Kleine-Budde <mkl@...gutronix.de>,
        Oliver Hartkopp <socketcan@...tkopp.net>,
        michael@...rulasolutions.com,
        Amarula patchwork <linux-amarula@...rulasolutions.com>,
        Jeroen Hofstee <jhofstee@...tronenergy.com>,
        Dario Binacchi <dario.binacchi@...rulasolutions.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Wolfgang Grandegger <wg@...ndegger.com>, netdev@...r.kernel.org
Subject: [RFC PATCH v3 6/9] can: slcan: add support for listen-only mode

For non-legacy, i.e. ip based configuration, add support for listen-only
mode. If listen-only is requested send a listen-only ("L\r") command
instead of an open ("O\r") command to the adapter.

Signed-off-by: Dario Binacchi <dario.binacchi@...rulasolutions.com>

---

(no changes since v2)

Changes in v2:
- Remove comment on listen-only command.
- Update the commit subject and description.

 drivers/net/can/slcan/slcan-core.c | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/drivers/net/can/slcan/slcan-core.c b/drivers/net/can/slcan/slcan-core.c
index d12d98426f37..45e521910236 100644
--- a/drivers/net/can/slcan/slcan-core.c
+++ b/drivers/net/can/slcan/slcan-core.c
@@ -726,10 +726,20 @@ static int slcan_netdev_open(struct net_device *dev)
 			}
 		}
 
-		err = slcan_transmit_cmd(sl, "O\r");
-		if (err) {
-			netdev_err(dev, "failed to send open command 'O\\r'\n");
-			goto cmd_transmit_failed;
+		if (sl->can.ctrlmode & CAN_CTRLMODE_LISTENONLY) {
+			err = slcan_transmit_cmd(sl, "L\r");
+			if (err) {
+				netdev_err(dev,
+					   "failed to send listen-only command 'L\\r'\n");
+				goto cmd_transmit_failed;
+			}
+		} else {
+			err = slcan_transmit_cmd(sl, "O\r");
+			if (err) {
+				netdev_err(dev,
+					   "failed to send open command 'O\\r'\n");
+				goto cmd_transmit_failed;
+			}
 		}
 	}
 
@@ -816,6 +826,7 @@ static int slcan_open(struct tty_struct *tty)
 	/* Configure CAN metadata */
 	sl->can.bitrate_const = slcan_bitrate_const;
 	sl->can.bitrate_const_cnt = ARRAY_SIZE(slcan_bitrate_const);
+	sl->can.ctrlmode_supported = CAN_CTRLMODE_LISTENONLY;
 
 	/* Configure netdev interface */
 	sl->dev	= dev;
-- 
2.32.0