netdev - [PATCH net-next 11/15] can: slcan: send the open/close commands to the adapter

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Date:   Sun,  3 Jul 2022 12:14:25 +0200
From:   Marc Kleine-Budde <mkl@...gutronix.de>
To:     netdev@...r.kernel.org
Cc:     davem@...emloft.net, kuba@...nel.org, linux-can@...r.kernel.org,
        kernel@...gutronix.de,
        Dario Binacchi <dario.binacchi@...rulasolutions.com>,
        Jeroen Hofstee <jhofstee@...tronenergy.com>,
        Marc Kleine-Budde <mkl@...gutronix.de>
Subject: [PATCH net-next 11/15] can: slcan: send the open/close commands to the adapter

From: Dario Binacchi <dario.binacchi@...rulasolutions.com>

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.

Link: https://lore.kernel.org/all/20220628163137.413025-9-dario.binacchi@amarulasolutions.com
Signed-off-by: Dario Binacchi <dario.binacchi@...rulasolutions.com>
Tested-by: Jeroen Hofstee <jhofstee@...tronenergy.com>
Signed-off-by: Marc Kleine-Budde <mkl@...gutronix.de>
---
 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 74033e2d7097..249b5ade06fc 100644
--- a/drivers/net/can/slcan.c
+++ b/drivers/net/can/slcan.c
@@ -435,9 +435,20 @@ 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);
 	}
@@ -496,14 +507,23 @@ 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)
-- 
2.35.1