On 25.07.2022 22:32:02, Vincent Mailhol wrote:
> Tools based on libpcap (such as tcpdump) expect the SIOCSHWTSTAMP
> ioctl call to be supported. This is also specified in the kernel doc
> [1]. The purpose of this ioctl is to toggle the hardware timestamps.
> 
> Currently, CAN devices which support hardware timestamping have those
> always activated. can_eth_ioctl_hwts() is a dumb function that will
> always succeed when requested to set tx_type to HWTSTAMP_TX_ON or
> rx_filter to HWTSTAMP_FILTER_ALL.
> 
> [1] Kernel doc: Timestamping, section 3.1 "Hardware Timestamping
> Implementation: Device Drivers"
> Link: https://docs.kernel.org/networking/timestamping.html#hardware-timestamping-implementation-device-drivers
> 
> Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
> ---
>  drivers/net/can/dev/dev.c | 29 +++++++++++++++++++++++++++++
>  include/linux/can/dev.h   |  1 +
>  2 files changed, 30 insertions(+)
> 
> diff --git a/drivers/net/can/dev/dev.c b/drivers/net/can/dev/dev.c
> index 7ad56d31cec9..750dc7cae9d4 100644
> --- a/drivers/net/can/dev/dev.c
> +++ b/drivers/net/can/dev/dev.c
> @@ -322,6 +322,35 @@ int can_change_mtu(struct net_device *dev, int new_mtu)
>  }
>  EXPORT_SYMBOL_GPL(can_change_mtu);
>  
> +/* generic implementation of netdev_ops::ndo_eth_ioctl for CAN devices
> + * supporting hardware RX timestamps
> + */
> +int can_eth_ioctl_hwts(struct net_device *netdev, struct ifreq *ifr, int cmd)
> +{
> +	struct hwtstamp_config hwts_cfg = { 0 };
> +
> +	switch (cmd) {
> +	case SIOCSHWTSTAMP: /* set */
> +		if (copy_from_user(&hwts_cfg, ifr->ifr_data, sizeof(hwts_cfg)))
> +			return -EFAULT;
> +		if (hwts_cfg.tx_type == HWTSTAMP_TX_ON &&
> +		    hwts_cfg.rx_filter == HWTSTAMP_FILTER_ALL)
> +			return 0;

I have a WIP hwts patch series for the mcp251xfd. IIRC the driver is
allowed to add RX timestamps to more packages than requested without
failing, so the relevant code my WIP patches looks like this:

+       switch (config.tx_type) {
+       case HWTSTAMP_TX_OFF:
+               break;
+       default:
+               return -ERANGE;
+       }
+
+       switch (config.rx_filter) {
+       case HWTSTAMP_FILTER_NONE:
+               clear_bit(MCP251XFD_FLAGS_TIMESTAMP_RX, priv->flags);
+               break;
+       default:
+               set_bit(MCP251XFD_FLAGS_TIMESTAMP_RX, priv->flags);
+               config.rx_filter = HWTSTAMP_FILTER_ALL;
+       }

Marc

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