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Date: Fri, 5 Nov 2021 19:36:01 -0700
From: Florian Fainelli <f.fainelli@...il.com>
To: Martin Kaistra <martin.kaistra@...utronix.de>,
Andrew Lunn <andrew@...n.ch>,
Vivien Didelot <vivien.didelot@...il.com>
Cc: Richard Cochran <richardcochran@...il.com>,
Vladimir Oltean <olteanv@...il.com>,
"David S. Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>,
John Stultz <john.stultz@...aro.org>,
Thomas Gleixner <tglx@...utronix.de>,
Stephen Boyd <sboyd@...nel.org>,
Russell King <linux@...linux.org.uk>,
Marc Kleine-Budde <mkl@...gutronix.de>,
linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH 5/7] net: dsa: b53: Add logic for RX timestamping
On 11/4/2021 6:31 AM, Martin Kaistra wrote:
> Packets received by the tagger with opcode=1 contain the 32-bit timestamp
> according to the timebase register. This timestamp is saved in
> BRCM_SKB_CB(skb)->meta_tstamp. b53_port_rxtstamp() takes this
> and puts the full time information from the timecounter into
> shwt->hwtstamp.
>
> Signed-off-by: Martin Kaistra <martin.kaistra@...utronix.de>
> ---
> drivers/net/dsa/b53/b53_common.c | 1 +
> drivers/net/dsa/b53/b53_ptp.c | 28 ++++++++++++++++++++++++++
> drivers/net/dsa/b53/b53_ptp.h | 10 ++++++++++
> include/linux/dsa/b53.h | 30 ++++++++++++++++++++++++++++
> net/dsa/tag_brcm.c | 34 ++++++++++++++++++++++----------
> 5 files changed, 93 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/net/dsa/b53/b53_common.c b/drivers/net/dsa/b53/b53_common.c
> index ed590efbd3bf..a9408f9cd414 100644
> --- a/drivers/net/dsa/b53/b53_common.c
> +++ b/drivers/net/dsa/b53/b53_common.c
> @@ -2300,6 +2300,7 @@ static const struct dsa_switch_ops b53_switch_ops = {
> .port_max_mtu = b53_get_max_mtu,
> .port_change_mtu = b53_change_mtu,
> .get_ts_info = b53_get_ts_info,
> + .port_rxtstamp = b53_port_rxtstamp,
> };
>
> struct b53_chip_data {
> diff --git a/drivers/net/dsa/b53/b53_ptp.c b/drivers/net/dsa/b53/b53_ptp.c
> index 324335465232..86ebaa522084 100644
> --- a/drivers/net/dsa/b53/b53_ptp.c
> +++ b/drivers/net/dsa/b53/b53_ptp.c
> @@ -6,6 +6,8 @@
> * Copyright (C) 2021 Linutronix GmbH
> */
>
> +#include <linux/ptp_classify.h>
> +
> #include "b53_priv.h"
> #include "b53_ptp.h"
>
> @@ -107,6 +109,32 @@ static void b53_ptp_overflow_check(struct work_struct *work)
> schedule_delayed_work(&dev->overflow_work, B53_PTP_OVERFLOW_PERIOD);
> }
>
> +bool b53_port_rxtstamp(struct dsa_switch *ds, int port, struct sk_buff *skb,
> + unsigned int type)
> +{
> + struct b53_device *dev = ds->priv;
> + struct b53_port_hwtstamp *ps = &dev->ports[port].port_hwtstamp;
> + struct skb_shared_hwtstamps *shwt;
> + u64 ns;
> +
> + if (type != PTP_CLASS_V2_L2)
> + return false;
> +
> + if (!test_bit(B53_HWTSTAMP_ENABLED, &ps->state))
> + return false;
> +
> + mutex_lock(&dev->ptp_mutex);
> + ns = BRCM_SKB_CB(skb)->meta_tstamp;
> + ns = timecounter_cyc2time(&dev->tc, ns);
Why not fold this directly:
ns = timecoutner_cyc2time(&dev->tc, (u64)BRCM_SKB_CB(skb)->meta_stamp)
> + mutex_unlock(&dev->ptp_mutex);
> +
> + shwt = skb_hwtstamps(skb);
> + memset(shwt, 0, sizeof(*shwt));
> + shwt->hwtstamp = ns_to_ktime(ns);
> +
> + return false;
> +}
> +
> int b53_ptp_init(struct b53_device *dev)
> {
> mutex_init(&dev->ptp_mutex);
> diff --git a/drivers/net/dsa/b53/b53_ptp.h b/drivers/net/dsa/b53/b53_ptp.h
> index 5cd2fd9621a2..3b3437870c55 100644
> --- a/drivers/net/dsa/b53/b53_ptp.h
> +++ b/drivers/net/dsa/b53/b53_ptp.h
> @@ -9,11 +9,15 @@
>
> #include "b53_priv.h"
>
> +#define SKB_PTP_TYPE(__skb) (*(unsigned int *)((__skb)->cb))
> +
> #ifdef CONFIG_B53_PTP
> int b53_ptp_init(struct b53_device *dev);
> void b53_ptp_exit(struct b53_device *dev);
> int b53_get_ts_info(struct dsa_switch *ds, int port,
> struct ethtool_ts_info *info);
> +bool b53_port_rxtstamp(struct dsa_switch *ds, int port, struct sk_buff *skb,
> + unsigned int type);
> #else /* !CONFIG_B53_PTP */
>
> static inline int b53_ptp_init(struct b53_device *dev)
> @@ -31,5 +35,11 @@ static inline int b53_get_ts_info(struct dsa_switch *ds, int port,
> return -EOPNOTSUPP;
> }
>
> +static inline bool b53_port_rxtstamp(struct dsa_switch *ds, int port,
> + struct sk_buff *skb, unsigned int type)
> +{
> + return false;
> +}
> +
> #endif
> #endif
> diff --git a/include/linux/dsa/b53.h b/include/linux/dsa/b53.h
> index 85aa6d9dc53d..542e5e3040d6 100644
> --- a/include/linux/dsa/b53.h
> +++ b/include/linux/dsa/b53.h
> @@ -46,9 +46,32 @@ struct b53_io_ops {
> struct phylink_link_state *state);
> };
>
> +/* state flags for b53_port_hwtstamp::state */
> +enum {
> + B53_HWTSTAMP_ENABLED,
> + B53_HWTSTAMP_TX_IN_PROGRESS,
> +};
> +
> +struct b53_port_hwtstamp {
> + /* Port index */
> + int port_id;
> +
> + /* Timestamping state */
> + unsigned long state;
> +
> + /* Resources for transmit timestamping */
> + unsigned long tx_tstamp_start;
> + struct sk_buff *tx_skb;
> +
> + /* Current timestamp configuration */
> + struct hwtstamp_config tstamp_config;
> +};
> +
> struct b53_port {
> u16 vlan_ctl_mask;
> struct ethtool_eee eee;
> + /* Per-port timestamping resources */
> + struct b53_port_hwtstamp port_hwtstamp;
> };
>
> struct b53_vlan {
> @@ -112,3 +135,10 @@ struct b53_device {
> #define B53_PTP_OVERFLOW_PERIOD (HZ / 2)
> struct delayed_work overflow_work;
> };
> +
> +struct brcm_skb_cb {
> + struct sk_buff *clone;
> + u32 meta_tstamp;
> +};
> +
> +#define BRCM_SKB_CB(skb) ((struct brcm_skb_cb *)(skb)->cb)
> diff --git a/net/dsa/tag_brcm.c b/net/dsa/tag_brcm.c
> index 96dbb8ee2fee..85dc47c22008 100644
> --- a/net/dsa/tag_brcm.c
> +++ b/net/dsa/tag_brcm.c
> @@ -9,6 +9,7 @@
> #include <linux/etherdevice.h>
> #include <linux/list.h>
> #include <linux/slab.h>
> +#include <linux/dsa/b53.h>
>
> #include "dsa_priv.h"
>
> @@ -31,7 +32,10 @@
> /* 6th byte in the tag */
> #define BRCM_LEG_PORT_ID (0xf)
>
> -/* Newer Broadcom tag (4 bytes) */
> +/* Newer Broadcom tag (4 bytes)
> + * For egress, when opcode = 0001, additional 4 bytes are used for
> + * the time stamp.
> + */
> #define BRCM_TAG_LEN 4
>
> /* Tag is constructed and desconstructed using byte by byte access
> @@ -136,19 +140,26 @@ static struct sk_buff *brcm_tag_xmit_ll(struct sk_buff *skb,
> */
> static struct sk_buff *brcm_tag_rcv_ll(struct sk_buff *skb,
> struct net_device *dev,
> - unsigned int offset)
> + unsigned int offset,
> + int *tag_len)
> {
> int source_port;
> u8 *brcm_tag;
> + u32 tstamp;
> +
> + *tag_len = 8;
I believe you have to do this in a two step process, first check that
you can pull 4 bytes, read the Broadcom tag's opcode, then pull the
additional 4 bytes if the opcode is 1.
>
> - if (unlikely(!pskb_may_pull(skb, BRCM_TAG_LEN)))
> + if (unlikely(!pskb_may_pull(skb, *tag_len)))
> return NULL;
>
> brcm_tag = skb->data - offset;
>
> - /* The opcode should never be different than 0b000 */
> - if (unlikely((brcm_tag[0] >> BRCM_OPCODE_SHIFT) & BRCM_OPCODE_MASK))
> - return NULL;
> + if ((brcm_tag[0] >> BRCM_OPCODE_SHIFT) & BRCM_OPCODE_MASK) {
> + tstamp = brcm_tag[4] << 24 | brcm_tag[5] << 16 | brcm_tag[6] << 8 | brcm_tag[7];
> + BRCM_SKB_CB(skb)->meta_tstamp = tstamp;
> + } else {
> + *tag_len = BRCM_TAG_LEN;
> + }
>
> /* We should never see a reserved reason code without knowing how to
> * handle it
> @@ -164,7 +175,7 @@ static struct sk_buff *brcm_tag_rcv_ll(struct sk_buff *skb,
> return NULL;
>
> /* Remove Broadcom tag and update checksum */
> - skb_pull_rcsum(skb, BRCM_TAG_LEN);
> + skb_pull_rcsum(skb, *tag_len);
>
> dsa_default_offload_fwd_mark(skb);
>
> @@ -184,13 +195,14 @@ static struct sk_buff *brcm_tag_xmit(struct sk_buff *skb,
> static struct sk_buff *brcm_tag_rcv(struct sk_buff *skb, struct net_device *dev)
> {
> struct sk_buff *nskb;
> + int tag_len;
>
> /* skb->data points to the EtherType, the tag is right before it */
> - nskb = brcm_tag_rcv_ll(skb, dev, 2);
> + nskb = brcm_tag_rcv_ll(skb, dev, 2, &tag_len);
> if (!nskb)
> return nskb;
>
> - dsa_strip_etype_header(skb, BRCM_TAG_LEN);
> + dsa_strip_etype_header(skb, tag_len);
>
> return nskb;
> }
> @@ -295,8 +307,10 @@ static struct sk_buff *brcm_tag_xmit_prepend(struct sk_buff *skb,
> static struct sk_buff *brcm_tag_rcv_prepend(struct sk_buff *skb,
> struct net_device *dev)
> {
> + int tag_len;
> +
> /* tag is prepended to the packet */
> - return brcm_tag_rcv_ll(skb, dev, ETH_HLEN);
> + return brcm_tag_rcv_ll(skb, dev, ETH_HLEN, &tag_len);
> }
>
> static const struct dsa_device_ops brcm_prepend_netdev_ops = {
>
--
Florian
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