netdev - [RFC PATCH 5/5] can: slcan: send the listen-only command to the adapter

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Message-Id: <20220716170007.2020037-6-dario.binacchi@amarulasolutions.com>
Date:   Sat, 16 Jul 2022 19:00:07 +0200
From:   Dario Binacchi <dario.binacchi@...rulasolutions.com>
To:     linux-kernel@...r.kernel.org
Cc:     Jeroen Hofstee <jhofstee@...tronenergy.com>,
        michael@...rulasolutions.com,
        Amarula patchwork <linux-amarula@...rulasolutions.com>,
        Dario Binacchi <dario.binacchi@...rulasolutions.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jakub Kicinski <kuba@...nel.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        Marc Kleine-Budde <mkl@...gutronix.de>,
        Paolo Abeni <pabeni@...hat.com>,
        Vincent Mailhol <mailhol.vincent@...adoo.fr>,
        Wolfgang Grandegger <wg@...ndegger.com>,
        linux-can@...r.kernel.org, netdev@...r.kernel.org
Subject: [RFC PATCH 5/5] can: slcan: send the listen-only command to the adapter

In case the bitrate has been set via ip tool, this patch changes the
driver to send the listen-only ("L\r") command to the adapter.

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

---

 drivers/net/can/slcan/slcan-core.c | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/drivers/net/can/slcan/slcan-core.c b/drivers/net/can/slcan/slcan-core.c
index 7a1540507ecd..d97dfeccbf9c 100644
--- a/drivers/net/can/slcan/slcan-core.c
+++ b/drivers/net/can/slcan/slcan-core.c
@@ -711,10 +711,21 @@ 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;
+		/* listen-only command overrides open command */
+		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;
+			}
 		}
 	}
 
@@ -801,6 +812,7 @@ 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