linux-kernel - [PATCH v4 08/12] can: slcan: send the open/close commands to the adapter

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Date:   Tue, 14 Jun 2022 14:28:17 +0200
From:   Dario Binacchi <dario.binacchi@...rulasolutions.com>
To:     linux-kernel@...r.kernel.org
Cc:     Amarula patchwork <linux-amarula@...rulasolutions.com>,
        Oliver Hartkopp <socketcan@...tkopp.net>,
        michael@...rulasolutions.com,
        Dario Binacchi <dario.binacchi@...rulasolutions.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Marc Kleine-Budde <mkl@...gutronix.de>,
        Paolo Abeni <pabeni@...hat.com>,
        Wolfgang Grandegger <wg@...ndegger.com>,
        linux-can@...r.kernel.org, netdev@...r.kernel.org
Subject: [PATCH v4 08/12] can: slcan: send the open/close commands to the adapter

In case the bitrate has been set via ip tool, this patch changes the
driver to send the open ("O\r") and close ("C\r) commands to the
adapter.

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

---

Changes in v4:
- Squashed to the patch [v3,09/13] can: slcan: send the close command to the adapter.
- Use the CAN_BITRATE_UNKNOWN macro.

Changes in v2:
- Improve the commit message.

 drivers/net/can/slcan.c | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/drivers/net/can/slcan.c b/drivers/net/can/slcan.c
index bd3cf53246c7..b08e63f59b8e 100644
--- a/drivers/net/can/slcan.c
+++ b/drivers/net/can/slcan.c
@@ -436,9 +436,20 @@ static int slcan_transmit_cmd(struct slcan *sl, const unsigned char *cmd)
 static int slc_close(struct net_device *dev)
 {
 	struct slcan *sl = netdev_priv(dev);
+	int err;
 
 	spin_lock_bh(&sl->lock);
 	if (sl->tty) {
+		if (sl->can.bittiming.bitrate &&
+		    sl->can.bittiming.bitrate != CAN_BITRATE_UNKNOWN) {
+			spin_unlock_bh(&sl->lock);
+			err = slcan_transmit_cmd(sl, "C\r");
+			spin_lock_bh(&sl->lock);
+			if (err)
+				netdev_warn(dev,
+					    "failed to send close command 'C\\r'\n");
+		}
+
 		/* TTY discipline is running. */
 		clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
 	}
@@ -497,14 +508,23 @@ static int slc_open(struct net_device *dev)
 			netdev_err(dev,
 				   "failed to send bitrate command 'C\\rS%d\\r'\n",
 				   s);
-			close_candev(dev);
-			return err;
+			goto cmd_transmit_failed;
+		}
+
+		err = slcan_transmit_cmd(sl, "O\r");
+		if (err) {
+			netdev_err(dev, "failed to send open command 'O\\r'\n");
+			goto cmd_transmit_failed;
 		}
 	}
 
 	sl->can.state = CAN_STATE_ERROR_ACTIVE;
 	netif_start_queue(dev);
 	return 0;
+
+cmd_transmit_failed:
+	close_candev(dev);
+	return err;
 }
 
 static void slc_dealloc(struct slcan *sl)
-- 
2.32.0