can: slcan: set bitrate by CAN device driver API

It allows to set the bitrate via ip tool, as it happens for the other
CAN device drivers. It still remains possible to set the bitrate via
slcand or slcan_attach utilities. In case the ip tool is used, the
driver will send the serial command to the adapter.

Link: https://lore.kernel.org/all/20220628163137.413025-8-dario.binacchi@amarulasolutions.com
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Tested-by: Jeroen Hofstee <jhofstee@victronenergy.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

diff --git a/drivers/net/can/slcan.c b/drivers/net/can/slcan.c
index dfccf8d6c9a559cfe19674075c929d9662ca6be8..74033e2d7097ec8583b47ac59d9d879fe5602f6d 100644 (file)
--- a/drivers/net/can/slcan.c
+++ b/drivers/net/can/slcan.c
@@ -104,6 +104,11 @@ struct slcan {
 
 static struct net_device **slcan_devs;
 
+static const u32 slcan_bitrate_const[] = {
+       10000, 20000, 50000, 100000, 125000,
+       250000, 500000, 800000, 1000000
+};
+
  /************************************************************************
   *                    SLCAN ENCAPSULATION FORMAT                       *
   ************************************************************************/
@@ -439,6 +444,9 @@ static int slc_close(struct net_device *dev)
        netif_stop_queue(dev);
        close_candev(dev);
        sl->can.state = CAN_STATE_STOPPED;
+       if (sl->can.bittiming.bitrate == CAN_BITRATE_UNKNOWN)
+               sl->can.bittiming.bitrate = CAN_BITRATE_UNSET;
+
        sl->rcount   = 0;
        sl->xleft    = 0;
        spin_unlock_bh(&sl->lock);
@@ -450,7 +458,8 @@ static int slc_close(struct net_device *dev)
 static int slc_open(struct net_device *dev)
 {
        struct slcan *sl = netdev_priv(dev);
-       int err;
+       unsigned char cmd[SLC_MTU];
+       int err, s;
 
        if (sl->tty == NULL)
                return -ENODEV;
@@ -460,15 +469,39 @@ static int slc_open(struct net_device *dev)
         * can.bittiming.bitrate is CAN_BITRATE_UNSET (0), causing
         * open_candev() to fail. So let's set to a fake value.
         */
-       sl->can.bittiming.bitrate = CAN_BITRATE_UNKNOWN;
+       if (sl->can.bittiming.bitrate == CAN_BITRATE_UNSET)
+               sl->can.bittiming.bitrate = CAN_BITRATE_UNKNOWN;
+
        err = open_candev(dev);
        if (err) {
                netdev_err(dev, "failed to open can device\n");
                return err;
        }
 
-       sl->can.state = CAN_STATE_ERROR_ACTIVE;
        sl->flags &= BIT(SLF_INUSE);
+
+       if (sl->can.bittiming.bitrate != CAN_BITRATE_UNKNOWN) {
+               for (s = 0; s < ARRAY_SIZE(slcan_bitrate_const); s++) {
+                       if (sl->can.bittiming.bitrate == slcan_bitrate_const[s])
+                               break;
+               }
+
+               /* The CAN framework has already validate the bitrate value,
+                * so we can avoid to check if `s' has been properly set.
+                */
+
+               snprintf(cmd, sizeof(cmd), "C\rS%d\r", s);
+               err = slcan_transmit_cmd(sl, cmd);
+               if (err) {
+                       netdev_err(dev,
+                                  "failed to send bitrate command 'C\\rS%d\\r'\n",
+                                  s);
+                       close_candev(dev);
+                       return err;
+               }
+       }
+
+       sl->can.state = CAN_STATE_ERROR_ACTIVE;
        netif_start_queue(dev);
        return 0;
 }
@@ -581,6 +614,8 @@ static struct slcan *slc_alloc(void)
        /* Initialize channel control data */
        sl->magic = SLCAN_MAGIC;
        sl->dev = dev;
+       sl->can.bitrate_const = slcan_bitrate_const;
+       sl->can.bitrate_const_cnt = ARRAY_SIZE(slcan_bitrate_const);
        spin_lock_init(&sl->lock);
        INIT_WORK(&sl->tx_work, slcan_transmit);
        init_waitqueue_head(&sl->xcmd_wait);