From: Vincent Mailhol <mailhol.vincent@xxxxxxxxxx> Some CAN device can measure the TDCV (Transmission Delay Compensation Value) automatically for each transmitted CAN frames. A callback function do_get_auto_tdcv() is added to retrieve that value. This function is used only if CAN_CTRLMODE_TDC_AUTO is enabled (if CAN_CTRLMODE_TDC_MANUAL is selected, the TDCV value is provided by the user). If the device does not support reporting of TDCV, do_get_auto_tdcv() should be set to NULL and TDCV will not be reported by the netlink interface. On success, do_get_auto_tdcv() shall return 0. If the value can not be measured by the device, for example because network is down or because no frames were transmitted yet, can_priv::do_get_auto_tdcv() shall return a negative error code (e.g. -EINVAL) to signify that the value is not yet available. In such cases, TDCV is not reported by the netlink interface. Link: https://lore.kernel.org/all/20210918095637.20108-6-mailhol.vincent@xxxxxxxxxx CC: Stefan Mätje <stefan.maetje@xxxxxx> Signed-off-by: Vincent Mailhol <mailhol.vincent@xxxxxxxxxx> Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx> --- drivers/net/can/dev/netlink.c | 15 ++++++++++++--- include/linux/can/dev.h | 1 + 2 files changed, 13 insertions(+), 3 deletions(-) diff --git a/drivers/net/can/dev/netlink.c b/drivers/net/can/dev/netlink.c index c77cc6ae88b6..95cca4e5251f 100644 --- a/drivers/net/can/dev/netlink.c +++ b/drivers/net/can/dev/netlink.c @@ -372,7 +372,8 @@ static size_t can_tdc_get_size(const struct net_device *dev) } if (can_tdc_is_enabled(priv)) { - if (priv->ctrlmode & CAN_CTRLMODE_TDC_MANUAL) + if (priv->ctrlmode & CAN_CTRLMODE_TDC_MANUAL || + priv->do_get_auto_tdcv) size += nla_total_size(sizeof(u32)); /* IFLA_CAN_TDCV */ size += nla_total_size(sizeof(u32)); /* IFLA_CAN_TDCO */ if (priv->tdc_const->tdcf_max) @@ -445,8 +446,16 @@ static int can_tdc_fill_info(struct sk_buff *skb, const struct net_device *dev) goto err_cancel; if (can_tdc_is_enabled(priv)) { - if (priv->ctrlmode & CAN_CTRLMODE_TDC_MANUAL && - nla_put_u32(skb, IFLA_CAN_TDC_TDCV, tdc->tdcv)) + u32 tdcv; + int err = -EINVAL; + + if (priv->ctrlmode & CAN_CTRLMODE_TDC_MANUAL) { + tdcv = tdc->tdcv; + err = 0; + } else if (priv->do_get_auto_tdcv) { + err = priv->do_get_auto_tdcv(dev, &tdcv); + } + if (!err && nla_put_u32(skb, IFLA_CAN_TDC_TDCV, tdcv)) goto err_cancel; if (nla_put_u32(skb, IFLA_CAN_TDC_TDCO, tdc->tdco)) goto err_cancel; diff --git a/include/linux/can/dev.h b/include/linux/can/dev.h index 6dacbbb41e68..b4aa0f048cab 100644 --- a/include/linux/can/dev.h +++ b/include/linux/can/dev.h @@ -82,6 +82,7 @@ struct can_priv { enum can_state *state); int (*do_get_berr_counter)(const struct net_device *dev, struct can_berr_counter *bec); + int (*do_get_auto_tdcv)(const struct net_device *dev, u32 *tdcv); unsigned int echo_skb_max; struct sk_buff **echo_skb; -- 2.33.0
