747e5eb31d
The SJA1105 switch family has a PTP_CLK pin which emits a signal with fixed 50% duty cycle, but variable frequency and programmable start time. On the second generation (P/Q/R/S) switches, this pin supports even more functionality. The use case described by the hardware documents talks about synchronization via oneshot pulses: given 2 sja1105 switches, arbitrarily designated as a master and a slave, the master emits a single pulse on PTP_CLK, while the slave is configured to timestamp this pulse received on its PTP_CLK pin (which must obviously be configured as input). The difference between the timestamps then exactly becomes the slave offset to the master. The only trouble with the above is that the hardware is very much tied into this use case only, and not very generic beyond that: - When emitting a oneshot pulse, instead of being told when to emit it, the switch just does it "now" and tells you later what time it was, via the PTPSYNCTS register. [ Incidentally, this is the same register that the slave uses to collect the ext_ts timestamp from, too. ] - On the sync slave, there is no interrupt mechanism on reception of a new extts, and no FIFO to buffer them, because in the foreseen use case, software is in control of both the master and the slave pins, so it "knows" when there's something to collect. These 2 problems mean that: - We don't support (at least yet) the quirky oneshot mode exposed by the hardware, just normal periodic output. - We abuse the hardware a little bit when we expose generic extts. Because there's no interrupt mechanism, we need to poll at double the frequency we expect to receive a pulse. Currently that means a non-configurable "twice a second". Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Acked-by: Richard Cochran <richardcochran@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
174 lines
4.3 KiB
C
174 lines
4.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/* Copyright (c) 2019, Vladimir Oltean <olteanv@gmail.com>
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*/
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#ifndef _SJA1105_PTP_H
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#define _SJA1105_PTP_H
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#if IS_ENABLED(CONFIG_NET_DSA_SJA1105_PTP)
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/* Timestamps are in units of 8 ns clock ticks (equivalent to
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* a fixed 125 MHz clock).
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*/
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#define SJA1105_TICK_NS 8
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static inline s64 ns_to_sja1105_ticks(s64 ns)
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{
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return ns / SJA1105_TICK_NS;
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}
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static inline s64 sja1105_ticks_to_ns(s64 ticks)
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{
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return ticks * SJA1105_TICK_NS;
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}
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/* Calculate the first base_time in the future that satisfies this
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* relationship:
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*
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* future_base_time = base_time + N x cycle_time >= now, or
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*
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* now - base_time
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* N >= ---------------
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* cycle_time
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*
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* Because N is an integer, the ceiling value of the above "a / b" ratio
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* is in fact precisely the floor value of "(a + b - 1) / b", which is
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* easier to calculate only having integer division tools.
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*/
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static inline s64 future_base_time(s64 base_time, s64 cycle_time, s64 now)
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{
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s64 a, b, n;
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if (base_time >= now)
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return base_time;
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a = now - base_time;
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b = cycle_time;
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n = div_s64(a + b - 1, b);
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return base_time + n * cycle_time;
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}
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struct sja1105_ptp_cmd {
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u64 startptpcp; /* start toggling PTP_CLK pin */
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u64 stopptpcp; /* stop toggling PTP_CLK pin */
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u64 ptpstrtsch; /* start schedule */
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u64 ptpstopsch; /* stop schedule */
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u64 resptp; /* reset */
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u64 corrclk4ts; /* use the corrected clock for timestamps */
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u64 ptpclkadd; /* enum sja1105_ptp_clk_mode */
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};
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struct sja1105_ptp_data {
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struct delayed_work extts_work;
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struct sk_buff_head skb_rxtstamp_queue;
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struct ptp_clock_info caps;
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struct ptp_clock *clock;
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struct sja1105_ptp_cmd cmd;
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/* Serializes all operations on the PTP hardware clock */
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struct mutex lock;
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u64 ptpsyncts;
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};
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int sja1105_ptp_clock_register(struct dsa_switch *ds);
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void sja1105_ptp_clock_unregister(struct dsa_switch *ds);
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void sja1105et_ptp_cmd_packing(u8 *buf, struct sja1105_ptp_cmd *cmd,
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enum packing_op op);
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void sja1105pqrs_ptp_cmd_packing(u8 *buf, struct sja1105_ptp_cmd *cmd,
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enum packing_op op);
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int sja1105_get_ts_info(struct dsa_switch *ds, int port,
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struct ethtool_ts_info *ts);
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void sja1105_ptp_txtstamp_skb(struct dsa_switch *ds, int slot,
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struct sk_buff *clone);
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bool sja1105_port_rxtstamp(struct dsa_switch *ds, int port,
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struct sk_buff *skb, unsigned int type);
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bool sja1105_port_txtstamp(struct dsa_switch *ds, int port,
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struct sk_buff *skb, unsigned int type);
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int sja1105_hwtstamp_get(struct dsa_switch *ds, int port, struct ifreq *ifr);
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int sja1105_hwtstamp_set(struct dsa_switch *ds, int port, struct ifreq *ifr);
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int __sja1105_ptp_gettimex(struct dsa_switch *ds, u64 *ns,
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struct ptp_system_timestamp *sts);
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int __sja1105_ptp_settime(struct dsa_switch *ds, u64 ns,
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struct ptp_system_timestamp *ptp_sts);
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int __sja1105_ptp_adjtime(struct dsa_switch *ds, s64 delta);
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int sja1105_ptp_commit(struct dsa_switch *ds, struct sja1105_ptp_cmd *cmd,
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sja1105_spi_rw_mode_t rw);
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#else
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struct sja1105_ptp_cmd;
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/* Structures cannot be empty in C. Bah!
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* Keep the mutex as the only element, which is a bit more difficult to
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* refactor out of sja1105_main.c anyway.
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*/
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struct sja1105_ptp_data {
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struct mutex lock;
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};
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static inline int sja1105_ptp_clock_register(struct dsa_switch *ds)
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{
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return 0;
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}
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static inline void sja1105_ptp_clock_unregister(struct dsa_switch *ds) { }
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static inline void sja1105_ptp_txtstamp_skb(struct dsa_switch *ds, int slot,
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struct sk_buff *clone)
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{
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}
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static inline int __sja1105_ptp_gettimex(struct dsa_switch *ds, u64 *ns,
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struct ptp_system_timestamp *sts)
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{
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return 0;
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}
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static inline int __sja1105_ptp_settime(struct dsa_switch *ds, u64 ns,
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struct ptp_system_timestamp *ptp_sts)
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{
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return 0;
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}
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static inline int __sja1105_ptp_adjtime(struct dsa_switch *ds, s64 delta)
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{
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return 0;
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}
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static inline int sja1105_ptp_commit(struct dsa_switch *ds,
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struct sja1105_ptp_cmd *cmd,
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sja1105_spi_rw_mode_t rw)
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{
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return 0;
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}
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#define sja1105et_ptp_cmd_packing NULL
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#define sja1105pqrs_ptp_cmd_packing NULL
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#define sja1105_get_ts_info NULL
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#define sja1105_port_rxtstamp NULL
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#define sja1105_port_txtstamp NULL
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#define sja1105_hwtstamp_get NULL
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#define sja1105_hwtstamp_set NULL
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#endif /* IS_ENABLED(CONFIG_NET_DSA_SJA1105_PTP) */
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#endif /* _SJA1105_PTP_H */
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