linux/drivers/net/dsa/sja1105/sja1105_ptp.h
Vladimir Oltean 566b18c8b7 net: dsa: sja1105: implement TX timestamping for SJA1110
The TX timestamping procedure for SJA1105 is a bit unconventional
because the transmit procedure itself is unconventional.

Control packets (and therefore PTP as well) are transmitted to a
specific port in SJA1105 using "management routes" which must be written
over SPI to the switch. These are one-shot rules that match by
destination MAC address on traffic coming from the CPU port, and select
the precise destination port for that packet. So to transmit a packet
from NET_TX softirq context, we actually need to defer to a process
context so that we can perform that SPI write before we send the packet.
The DSA master dev_queue_xmit() runs in process context, and we poll
until the switch confirms it took the TX timestamp, then we annotate the
skb clone with that TX timestamp. This is why the sja1105 driver does
not need an skb queue for TX timestamping.

But the SJA1110 is a bit (not much!) more conventional, and you can
request 2-step TX timestamping through the DSA header, as well as give
the switch a cookie (timestamp ID) which it will give back to you when
it has the timestamp. So now we do need a queue for keeping the skb
clones until their TX timestamps become available.

The interesting part is that the metadata frames from SJA1105 haven't
disappeared completely. On SJA1105 they were used as follow-ups which
contained RX timestamps, but on SJA1110 they are actually TX completion
packets, which contain a variable (up to 32) array of timestamps.
Why an array? Because:
- not only is the TX timestamp on the egress port being communicated,
  but also the RX timestamp on the CPU port. Nice, but we don't care
  about that, so we ignore it.
- because a packet could be multicast to multiple egress ports, each
  port takes its own timestamp, and the TX completion packet contains
  the individual timestamps on each port.

This is unconventional because switches typically have a timestamping
FIFO and raise an interrupt, but this one doesn't. So the tagger needs
to detect and parse meta frames, and call into the main switch driver,
which pairs the timestamps with the skbs in the TX timestamping queue
which are waiting for one.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2021-06-11 12:45:38 -07:00

203 lines
5.1 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
/* Copyright (c) 2019, Vladimir Oltean <olteanv@gmail.com>
*/
#ifndef _SJA1105_PTP_H
#define _SJA1105_PTP_H
#include <linux/timer.h>
#if IS_ENABLED(CONFIG_NET_DSA_SJA1105_PTP)
/* Timestamps are in units of 8 ns clock ticks (equivalent to
* a fixed 125 MHz clock).
*/
#define SJA1105_TICK_NS 8
static inline s64 ns_to_sja1105_ticks(s64 ns)
{
return ns / SJA1105_TICK_NS;
}
static inline s64 sja1105_ticks_to_ns(s64 ticks)
{
return ticks * SJA1105_TICK_NS;
}
/* Calculate the first base_time in the future that satisfies this
* relationship:
*
* future_base_time = base_time + N x cycle_time >= now, or
*
* now - base_time
* N >= ---------------
* cycle_time
*
* Because N is an integer, the ceiling value of the above "a / b" ratio
* is in fact precisely the floor value of "(a + b - 1) / b", which is
* easier to calculate only having integer division tools.
*/
static inline s64 future_base_time(s64 base_time, s64 cycle_time, s64 now)
{
s64 a, b, n;
if (base_time >= now)
return base_time;
a = now - base_time;
b = cycle_time;
n = div_s64(a + b - 1, b);
return base_time + n * cycle_time;
}
/* This is not a preprocessor macro because the "ns" argument may or may not be
* s64 at caller side. This ensures it is properly type-cast before div_s64.
*/
static inline s64 ns_to_sja1105_delta(s64 ns)
{
return div_s64(ns, 200);
}
static inline s64 sja1105_delta_to_ns(s64 delta)
{
return delta * 200;
}
struct sja1105_ptp_cmd {
u64 startptpcp; /* start toggling PTP_CLK pin */
u64 stopptpcp; /* stop toggling PTP_CLK pin */
u64 ptpstrtsch; /* start schedule */
u64 ptpstopsch; /* stop schedule */
u64 resptp; /* reset */
u64 corrclk4ts; /* use the corrected clock for timestamps */
u64 ptpclkadd; /* enum sja1105_ptp_clk_mode */
};
struct sja1105_ptp_data {
struct timer_list extts_timer;
/* Used only on SJA1105 to reconstruct partial timestamps */
struct sk_buff_head skb_rxtstamp_queue;
/* Used on SJA1110 where meta frames are generated only for
* 2-step TX timestamps
*/
struct sk_buff_head skb_txtstamp_queue;
struct ptp_clock_info caps;
struct ptp_clock *clock;
struct sja1105_ptp_cmd cmd;
/* Serializes all operations on the PTP hardware clock */
struct mutex lock;
bool extts_enabled;
u64 ptpsyncts;
};
int sja1105_ptp_clock_register(struct dsa_switch *ds);
void sja1105_ptp_clock_unregister(struct dsa_switch *ds);
void sja1105et_ptp_cmd_packing(u8 *buf, struct sja1105_ptp_cmd *cmd,
enum packing_op op);
void sja1105pqrs_ptp_cmd_packing(u8 *buf, struct sja1105_ptp_cmd *cmd,
enum packing_op op);
int sja1105_get_ts_info(struct dsa_switch *ds, int port,
struct ethtool_ts_info *ts);
void sja1105_ptp_txtstamp_skb(struct dsa_switch *ds, int slot,
struct sk_buff *clone);
bool sja1105_port_rxtstamp(struct dsa_switch *ds, int port,
struct sk_buff *skb, unsigned int type);
void sja1105_port_txtstamp(struct dsa_switch *ds, int port,
struct sk_buff *skb);
int sja1105_hwtstamp_get(struct dsa_switch *ds, int port, struct ifreq *ifr);
int sja1105_hwtstamp_set(struct dsa_switch *ds, int port, struct ifreq *ifr);
int __sja1105_ptp_gettimex(struct dsa_switch *ds, u64 *ns,
struct ptp_system_timestamp *sts);
int __sja1105_ptp_settime(struct dsa_switch *ds, u64 ns,
struct ptp_system_timestamp *ptp_sts);
int __sja1105_ptp_adjtime(struct dsa_switch *ds, s64 delta);
int sja1105_ptp_commit(struct dsa_switch *ds, struct sja1105_ptp_cmd *cmd,
sja1105_spi_rw_mode_t rw);
bool sja1105_rxtstamp(struct dsa_switch *ds, int port, struct sk_buff *skb);
bool sja1110_rxtstamp(struct dsa_switch *ds, int port, struct sk_buff *skb);
void sja1110_txtstamp(struct dsa_switch *ds, int port, struct sk_buff *skb);
#else
struct sja1105_ptp_cmd;
/* Structures cannot be empty in C. Bah!
* Keep the mutex as the only element, which is a bit more difficult to
* refactor out of sja1105_main.c anyway.
*/
struct sja1105_ptp_data {
struct mutex lock;
};
static inline int sja1105_ptp_clock_register(struct dsa_switch *ds)
{
return 0;
}
static inline void sja1105_ptp_clock_unregister(struct dsa_switch *ds) { }
static inline void sja1105_ptp_txtstamp_skb(struct dsa_switch *ds, int slot,
struct sk_buff *clone)
{
}
static inline int __sja1105_ptp_gettimex(struct dsa_switch *ds, u64 *ns,
struct ptp_system_timestamp *sts)
{
return 0;
}
static inline int __sja1105_ptp_settime(struct dsa_switch *ds, u64 ns,
struct ptp_system_timestamp *ptp_sts)
{
return 0;
}
static inline int __sja1105_ptp_adjtime(struct dsa_switch *ds, s64 delta)
{
return 0;
}
static inline int sja1105_ptp_commit(struct dsa_switch *ds,
struct sja1105_ptp_cmd *cmd,
sja1105_spi_rw_mode_t rw)
{
return 0;
}
#define sja1105et_ptp_cmd_packing NULL
#define sja1105pqrs_ptp_cmd_packing NULL
#define sja1105_get_ts_info NULL
#define sja1105_port_rxtstamp NULL
#define sja1105_port_txtstamp NULL
#define sja1105_hwtstamp_get NULL
#define sja1105_hwtstamp_set NULL
#define sja1105_rxtstamp NULL
#define sja1110_rxtstamp NULL
#define sja1110_txtstamp NULL
#endif /* IS_ENABLED(CONFIG_NET_DSA_SJA1105_PTP) */
#endif /* _SJA1105_PTP_H */