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can: netlink: add can_priv::do_get_auto_tdcv() to retrieve tdcv from device

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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@wanadoo.fr
CC: Stefan Mätje <stefan.maetje@esd.eu>
Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
This commit is contained in:
Vincent Mailhol 2021-09-18 18:56:36 +09:00 committed by Marc Kleine-Budde
parent d99755f71a
commit e8060f08cd
2 changed files with 13 additions and 3 deletions
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15
drivers/net/can/dev/netlink.c
View File

@ -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;

1
include/linux/can/dev.h
View File

@ -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;