Re: [net-next 3/3] net: mscc: ocelot: support PTP Sync one-step timestamping

[Vladimir Oltean]

On Fri, Apr 16, 2021 at 08:36:55PM +0800, Yangbo Lu wrote:
> Although HWTSTAMP_TX_ONESTEP_SYNC existed in ioctl for hardware timestamp
> configuration, the PTP Sync one-step timestamping had never been supported.
> 
> This patch is to truely support it.

Actually the ocelot switchdev driver does support one-step timestamping,
just the felix DSA driver does not.

> The hardware timestamp request type is
> stored in DSA_SKB_CB_PRIV first byte per skb, so that corresponding
> configuration could be done during transmitting. Non-onestep-Sync packet
> with one-step timestamp request should fall back to use two-step timestamp.
> 
> Signed-off-by: Yangbo Lu <yangbo.lu@xxxxxxx>
> ---
>  drivers/net/ethernet/mscc/ocelot.c     | 57 ++++++++++++++++++++++++++
>  drivers/net/ethernet/mscc/ocelot_net.c |  5 +--
>  include/soc/mscc/ocelot.h              |  1 +
>  net/dsa/tag_ocelot.c                   | 25 ++---------
>  net/dsa/tag_ocelot_8021q.c             | 39 +++++-------------
>  5 files changed, 72 insertions(+), 55 deletions(-)
> 
> diff --git a/drivers/net/ethernet/mscc/ocelot.c b/drivers/net/ethernet/mscc/ocelot.c
> index 541d3b4076be..69d36b6241ff 100644
> --- a/drivers/net/ethernet/mscc/ocelot.c
> +++ b/drivers/net/ethernet/mscc/ocelot.c
> @@ -6,6 +6,7 @@
>   */
>  #include <linux/dsa/ocelot.h>
>  #include <linux/if_bridge.h>
> +#include <linux/ptp_classify.h>
>  #include <soc/mscc/ocelot_vcap.h>
>  #include "ocelot.h"
>  #include "ocelot_vcap.h"
> @@ -546,6 +547,50 @@ static void ocelot_port_add_txtstamp_skb(struct ocelot *ocelot, int port,
>  	spin_unlock(&ocelot_port->ts_id_lock);
>  }
>  
> +bool ocelot_ptp_rew_op(struct sk_buff *skb, struct sk_buff *clone, u32 *rew_op)
> +{
> +	/* For two-step timestamp, retrieve ptp_cmd in DSA_SKB_CB_PRIV
> +	 * and timestamp ID in clone->cb[0].
> +	 * For one-step timestamp, retrieve ptp_cmd in DSA_SKB_CB_PRIV.
> +	 */
> +	u8 *ptp_cmd = DSA_SKB_CB_PRIV(skb);

This is fine in the sense that it works, but please consider creating
something similar to sja1105:

struct ocelot_skb_cb {
	u8 ptp_cmd; /* For both one-step and two-step timestamping */
	u8 ts_id; /* Only for two-step timestamping */
};

#define OCELOT_SKB_CB(skb) \
	((struct ocelot_skb_cb *)DSA_SKB_CB_PRIV(skb))

And then access as OCELOT_SKB_CB(skb)->ptp_cmd, OCELOT_SKB_CB(clone)->ts_id.

and put a comment to explain that this is done in order to have common
code between Felix DSA and Ocelot switchdev. Basically Ocelot will not
use the first 8 bytes of skb->cb, but there's enough space for this to
not make any difference. The original skb will hold only ptp_cmd, the
clone will only hold ts_id, but it helps to have the same structure in
place.

If you create this ocelot_skb_cb structure, I expect the comment above
to be fairly redundant, you can consider removing it.

> +
> +	if (clone) {
> +		*rew_op = *ptp_cmd;
> +		*rew_op |= clone->cb[0] << 3;
> +	} else if (*ptp_cmd) {
> +		*rew_op = *ptp_cmd;
> +	} else {
> +		return false;
> +	}
> +
> +	return true;

Just make this function return an u32. If the packet isn't PTP, the
rew_op will be 0.

> +}
> +EXPORT_SYMBOL(ocelot_ptp_rew_op);
> +
> +static bool ocelot_ptp_is_onestep_sync(struct sk_buff *skb)
> +{
> +	struct ptp_header *hdr;
> +	unsigned int ptp_class;
> +	u8 msgtype, twostep;
> +
> +	ptp_class = ptp_classify_raw(skb);
> +	if (ptp_class == PTP_CLASS_NONE)
> +		return false;
> +
> +	hdr = ptp_parse_header(skb, ptp_class);
> +	if (!hdr)
> +		return false;
> +
> +	msgtype = ptp_get_msgtype(hdr, ptp_class);
> +	twostep = hdr->flag_field[0] & 0x2;
> +
> +	if (msgtype == PTP_MSGTYPE_SYNC && twostep == 0)
> +		return true;
> +
> +	return false;
> +}
> +

This is generic, but if you were to move it to net/core/ptp_classifier.c,
I think you would have to pass the output of ptp_classify_raw() as an
"unsigned int type" argument. So I think I would leave it the way it is
for now - inside of ocelot - until somebody else needs something
similar, and we see what is the required prototype.

>  int ocelot_port_txtstamp_request(struct ocelot *ocelot, int port,
>  				 struct sk_buff *skb,
>  				 struct sk_buff **clone)
> @@ -553,12 +598,24 @@ int ocelot_port_txtstamp_request(struct ocelot *ocelot, int port,
>  	struct ocelot_port *ocelot_port = ocelot->ports[port];
>  	u8 ptp_cmd = ocelot_port->ptp_cmd;
>  
> +	/* Store ptp_cmd in first byte of DSA_SKB_CB_PRIV per skb */
> +	if (ptp_cmd == IFH_REW_OP_ORIGIN_PTP) {
> +		if (ocelot_ptp_is_onestep_sync(skb)) {
> +			*(u8 *)DSA_SKB_CB_PRIV(skb) = ptp_cmd;
> +			return 0;
> +		}
> +
> +		/* Fall back to two-step timestamping */
> +		ptp_cmd = IFH_REW_OP_TWO_STEP_PTP;
> +	}
> +
>  	if (ptp_cmd == IFH_REW_OP_TWO_STEP_PTP) {
>  		*clone = skb_clone_sk(skb);
>  		if (!(*clone))
>  			return -ENOMEM;
>  
>  		ocelot_port_add_txtstamp_skb(ocelot, port, *clone);
> +		*(u8 *)DSA_SKB_CB_PRIV(skb) = ptp_cmd;
>  	}
>  
>  	return 0;
> diff --git a/drivers/net/ethernet/mscc/ocelot_net.c b/drivers/net/ethernet/mscc/ocelot_net.c
> index 8293152a6dc1..eb3d525731da 100644
> --- a/drivers/net/ethernet/mscc/ocelot_net.c
> +++ b/drivers/net/ethernet/mscc/ocelot_net.c
> @@ -514,10 +514,7 @@ static netdev_tx_t ocelot_port_xmit(struct sk_buff *skb, struct net_device *dev)
>  			return NETDEV_TX_OK;
>  		}
>  
> -		if (ocelot_port->ptp_cmd == IFH_REW_OP_TWO_STEP_PTP) {
> -			rew_op = ocelot_port->ptp_cmd;
> -			rew_op |= clone->cb[0] << 3;
> -		}
> +		ocelot_ptp_rew_op(skb, clone, &rew_op);
>  	}
>  
>  	ocelot_port_inject_frame(ocelot, port, 0, rew_op, skb);
> diff --git a/include/soc/mscc/ocelot.h b/include/soc/mscc/ocelot.h
> index 9cdaf1d9199f..19413532db0b 100644
> --- a/include/soc/mscc/ocelot.h
> +++ b/include/soc/mscc/ocelot.h
> @@ -820,6 +820,7 @@ int ocelot_vlan_add(struct ocelot *ocelot, int port, u16 vid, bool pvid,
>  int ocelot_vlan_del(struct ocelot *ocelot, int port, u16 vid);
>  int ocelot_hwstamp_get(struct ocelot *ocelot, int port, struct ifreq *ifr);
>  int ocelot_hwstamp_set(struct ocelot *ocelot, int port, struct ifreq *ifr);
> +bool ocelot_ptp_rew_op(struct sk_buff *skb, struct sk_buff *clone, u32 *rew_op);
>  int ocelot_port_txtstamp_request(struct ocelot *ocelot, int port,
>  				 struct sk_buff *skb,
>  				 struct sk_buff **clone);
> diff --git a/net/dsa/tag_ocelot.c b/net/dsa/tag_ocelot.c
> index f9df9cac81c5..d5c73b36f0c1 100644
> --- a/net/dsa/tag_ocelot.c
> +++ b/net/dsa/tag_ocelot.c
> @@ -5,25 +5,6 @@
>  #include <soc/mscc/ocelot.h>
>  #include "dsa_priv.h"
>  
> -static void ocelot_xmit_ptp(struct dsa_port *dp, void *injection,
> -			    struct sk_buff *clone)
> -{
> -	struct ocelot *ocelot = dp->ds->priv;
> -	struct ocelot_port *ocelot_port;
> -	u64 rew_op;
> -
> -	ocelot_port = ocelot->ports[dp->index];
> -	rew_op = ocelot_port->ptp_cmd;
> -
> -	/* Retrieve timestamp ID populated inside skb->cb[0] of the
> -	 * clone by ocelot_port_add_txtstamp_skb
> -	 */
> -	if (ocelot_port->ptp_cmd == IFH_REW_OP_TWO_STEP_PTP)
> -		rew_op |= clone->cb[0] << 3;
> -
> -	ocelot_ifh_set_rew_op(injection, rew_op);
> -}
> -
>  static void ocelot_xmit_common(struct sk_buff *skb, struct net_device *netdev,
>  			       __be32 ifh_prefix, void **ifh)
>  {
> @@ -32,6 +13,7 @@ static void ocelot_xmit_common(struct sk_buff *skb, struct net_device *netdev,
>  	struct dsa_switch *ds = dp->ds;
>  	void *injection;
>  	__be32 *prefix;
> +	u32 rew_op = 0;
>  
>  	injection = skb_push(skb, OCELOT_TAG_LEN);
>  	prefix = skb_push(skb, OCELOT_SHORT_PREFIX_LEN);
> @@ -42,9 +24,8 @@ static void ocelot_xmit_common(struct sk_buff *skb, struct net_device *netdev,
>  	ocelot_ifh_set_src(injection, ds->num_ports);
>  	ocelot_ifh_set_qos_class(injection, skb->priority);
>  
> -	/* TX timestamping was requested */
> -	if (clone)
> -		ocelot_xmit_ptp(dp, injection, clone);
> +	if (ocelot_ptp_rew_op(skb, clone, &rew_op))
> +		ocelot_ifh_set_rew_op(injection, rew_op);
>  
>  	*ifh = injection;
>  }
> diff --git a/net/dsa/tag_ocelot_8021q.c b/net/dsa/tag_ocelot_8021q.c
> index 5f3e8e124a82..bf32649a5a7b 100644
> --- a/net/dsa/tag_ocelot_8021q.c
> +++ b/net/dsa/tag_ocelot_8021q.c
> @@ -13,32 +13,6 @@
>  #include <soc/mscc/ocelot_ptp.h>
>  #include "dsa_priv.h"
>  
> -static struct sk_buff *ocelot_xmit_ptp(struct dsa_port *dp,
> -				       struct sk_buff *skb,
> -				       struct sk_buff *clone)
> -{
> -	struct ocelot *ocelot = dp->ds->priv;
> -	struct ocelot_port *ocelot_port;
> -	int port = dp->index;
> -	u32 rew_op;
> -
> -	if (!ocelot_can_inject(ocelot, 0))
> -		return NULL;
> -
> -	ocelot_port = ocelot->ports[port];
> -	rew_op = ocelot_port->ptp_cmd;
> -
> -	/* Retrieve timestamp ID populated inside skb->cb[0] of the
> -	 * clone by ocelot_port_add_txtstamp_skb
> -	 */
> -	if (ocelot_port->ptp_cmd == IFH_REW_OP_TWO_STEP_PTP)
> -		rew_op |= clone->cb[0] << 3;
> -
> -	ocelot_port_inject_frame(ocelot, port, 0, rew_op, skb);
> -
> -	return NULL;
> -}
> -
>  static struct sk_buff *ocelot_xmit(struct sk_buff *skb,
>  				   struct net_device *netdev)
>  {
> @@ -47,10 +21,17 @@ static struct sk_buff *ocelot_xmit(struct sk_buff *skb,
>  	u16 queue_mapping = skb_get_queue_mapping(skb);
>  	u8 pcp = netdev_txq_to_tc(netdev, queue_mapping);
>  	struct sk_buff *clone = DSA_SKB_CB(skb)->clone;
> +	struct ocelot *ocelot = dp->ds->priv;
> +	int port = dp->index;
> +	u32 rew_op = 0;
> +
> +	if (ocelot_ptp_rew_op(skb, clone, &rew_op)) {
> +		if (!ocelot_can_inject(ocelot, 0))
> +			return NULL;
>  
> -	/* TX timestamping was requested, so inject through MMIO */
> -	if (clone)
> -		return ocelot_xmit_ptp(dp, skb, clone);
> +		ocelot_port_inject_frame(ocelot, port, 0, rew_op, skb);
> +		return NULL;
> +	}
>  
>  	return dsa_8021q_xmit(skb, netdev, ETH_P_8021Q,
>  			      ((pcp << VLAN_PRIO_SHIFT) | tx_vid));
> -- 
> 2.25.1
>