linux/drivers/net/dsa/sja1105/sja1105_ptp.h
Vladimir Oltean 6d709cadfd net: dsa: move sja1110_process_meta_tstamp inside the tagging protocol driver
The problem is that DSA tagging protocols really must not depend on the
switch driver, because this creates a circular dependency at insmod
time, and the switch driver will effectively not load when the tagging
protocol driver is missing.

The code was structured in the way it was for a reason, though. The DSA
driver-facing API for PTP timestamping relies on the assumption that
two-step TX timestamps are provided by the hardware in an out-of-band
manner, typically by raising an interrupt and making that timestamp
available inside some sort of FIFO which is to be accessed over
SPI/MDIO/etc.

So the API puts .port_txtstamp into dsa_switch_ops, because it is
expected that the switch driver needs to save some state (like put the
skb into a queue until its TX timestamp arrives).

On SJA1110, TX timestamps are provided by the switch as Ethernet
packets, so this makes them be received and processed by the tagging
protocol driver. This in itself is great, because the timestamps are
full 64-bit and do not require reconstruction, and since Ethernet is the
fastest I/O method available to/from the switch, PTP timestamps arrive
very quickly, no matter how bottlenecked the SPI connection is, because
SPI interaction is not needed at all.

DSA's code structure and strict isolation between the tagging protocol
driver and the switch driver break the natural code organization.

When the tagging protocol driver receives a packet which is classified
as a metadata packet containing timestamps, it passes those timestamps
one by one to the switch driver, which then proceeds to compare them
based on the recorded timestamp ID that was generated in .port_txtstamp.

The communication between the tagging protocol and the switch driver is
done through a method exported by the switch driver, sja1110_process_meta_tstamp.
To satisfy build requirements, we force a dependency to build the
tagging protocol driver as a module when the switch driver is a module.
However, as explained in the first paragraph, that causes the circular
dependency.

To solve this, move the skb queue from struct sja1105_private :: struct
sja1105_ptp_data to struct sja1105_private :: struct sja1105_tagger_data.
The latter is a data structure for which hacks have already been put
into place to be able to create persistent storage per switch that is
accessible from the tagging protocol driver (see sja1105_setup_ports).

With the skb queue directly accessible from the tagging protocol driver,
we can now move sja1110_process_meta_tstamp into the tagging driver
itself, and avoid exporting a symbol.

Fixes: 566b18c8b752 ("net: dsa: sja1105: implement TX timestamping for SJA1110")
Link: https://lore.kernel.org/netdev/20210908220834.d7gmtnwrorhharna@skbuf/
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2021-09-23 12:45:07 +01:00

184 lines
4.7 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)
/* 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;
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 */