can: dev: can_changelink: allow to set bitrate on devices not providing {data_,}bitti...

Until commit

    08da7da41ea4 can: provide a separate bittiming_const parameter to
                 bittiming functions

it was possible to have devices not providing bittiming_const. This can
be used for hardware that only support pre-defined fixed bitrates.
Although no mainline driver is using this feature so far.

This patch re-introduces this feature for the bitrate and the data
bitrate (of CANFD controllers). The driver can specify the
{data_,}bittiming_const (if the bittiming parameters should be
calculated from the bittiming_const) as before or no
{data_,}bittiming_const but implement the do_set_{data,}bittiming
callback.

Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c
index fefe2cd..afcf487 100644 (file)
--- a/drivers/net/can/dev.c
+++ b/drivers/net/can/dev.c
@@ -284,10 +284,6 @@ static int can_get_bittiming(struct net_device *dev, struct can_bittiming *bt,
 {
        int err;
 
-       /* Check if the CAN device has bit-timing parameters */
-       if (!btc)
-               return -EOPNOTSUPP;
-
        /*
         * Depending on the given can_bittiming parameter structure the CAN
         * timing parameters are calculated based on the provided bitrate OR
@@ -872,10 +868,22 @@ static int can_changelink(struct net_device *dev,
                /* Do not allow changing bittiming while running */
                if (dev->flags & IFF_UP)
                        return -EBUSY;
+
+               /* Calculate bittiming parameters based on
+                * bittiming_const if set, otherwise pass bitrate
+                * directly via do_set_bitrate(). Bail out if neither
+                * is given.
+                */
+               if (!priv->bittiming_const && !priv->do_set_bittiming)
+                       return -EOPNOTSUPP;
+
                memcpy(&bt, nla_data(data[IFLA_CAN_BITTIMING]), sizeof(bt));
-               err = can_get_bittiming(dev, &bt, priv->bittiming_const);
-               if (err)
-                       return err;
+               if (priv->bittiming_const) {
+                       err = can_get_bittiming(dev, &bt,
+                                               priv->bittiming_const);
+                       if (err)
+                               return err;
+               }
                memcpy(&priv->bittiming, &bt, sizeof(bt));
 
                if (priv->do_set_bittiming) {
@@ -943,11 +951,23 @@ static int can_changelink(struct net_device *dev,
                /* Do not allow changing bittiming while running */
                if (dev->flags & IFF_UP)
                        return -EBUSY;
+
+               /* Calculate bittiming parameters based on
+                * data_bittiming_const if set, otherwise pass bitrate
+                * directly via do_set_bitrate(). Bail out if neither
+                * is given.
+                */
+               if (!priv->data_bittiming_const && !priv->do_set_data_bittiming)
+                       return -EOPNOTSUPP;
+
                memcpy(&dbt, nla_data(data[IFLA_CAN_DATA_BITTIMING]),
                       sizeof(dbt));
-               err = can_get_bittiming(dev, &dbt, priv->data_bittiming_const);
-               if (err)
-                       return err;
+               if (priv->data_bittiming_const) {
+                       err = can_get_bittiming(dev, &dbt,
+                                               priv->data_bittiming_const);
+                       if (err)
+                               return err;
+               }
                memcpy(&priv->data_bittiming, &dbt, sizeof(dbt));
 
                if (priv->do_set_data_bittiming) {