diff options
Diffstat (limited to 'drivers/net/dsa/sja1105/sja1105_ptp.c')
| -rw-r--r-- | drivers/net/dsa/sja1105/sja1105_ptp.c | 393 |
1 files changed, 393 insertions, 0 deletions
diff --git a/drivers/net/dsa/sja1105/sja1105_ptp.c b/drivers/net/dsa/sja1105/sja1105_ptp.c new file mode 100644 index 000000000000..d19cfdf681af --- /dev/null +++ b/drivers/net/dsa/sja1105/sja1105_ptp.c @@ -0,0 +1,393 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2019, Vladimir Oltean <olteanv@gmail.com> + */ +#include "sja1105.h" + +/* The adjfine API clamps ppb between [-32,768,000, 32,768,000], and + * therefore scaled_ppm between [-2,147,483,648, 2,147,483,647]. + * Set the maximum supported ppb to a round value smaller than the maximum. + * + * Percentually speaking, this is a +/- 0.032x adjustment of the + * free-running counter (0.968x to 1.032x). + */ +#define SJA1105_MAX_ADJ_PPB 32000000 +#define SJA1105_SIZE_PTP_CMD 4 + +/* Timestamps are in units of 8 ns clock ticks (equivalent to a fixed + * 125 MHz clock) so the scale factor (MULT / SHIFT) needs to be 8. + * Furthermore, wisely pick SHIFT as 28 bits, which translates + * MULT into 2^31 (0x80000000). This is the same value around which + * the hardware PTPCLKRATE is centered, so the same ppb conversion + * arithmetic can be reused. + */ +#define SJA1105_CC_SHIFT 28 +#define SJA1105_CC_MULT (8 << SJA1105_CC_SHIFT) + +/* Having 33 bits of cycle counter left until a 64-bit overflow during delta + * conversion, we multiply this by the 8 ns counter resolution and arrive at + * a comfortable 68.71 second refresh interval until the delta would cause + * an integer overflow, in absence of any other readout. + * Approximate to 1 minute. + */ +#define SJA1105_REFRESH_INTERVAL (HZ * 60) + +/* This range is actually +/- SJA1105_MAX_ADJ_PPB + * divided by 1000 (ppb -> ppm) and with a 16-bit + * "fractional" part (actually fixed point). + * | + * v + * Convert scaled_ppm from the +/- ((10^6) << 16) range + * into the +/- (1 << 31) range. + * + * This forgoes a "ppb" numeric representation (up to NSEC_PER_SEC) + * and defines the scaling factor between scaled_ppm and the actual + * frequency adjustments (both cycle counter and hardware). + * + * ptpclkrate = scaled_ppm * 2^31 / (10^6 * 2^16) + * simplifies to + * ptpclkrate = scaled_ppm * 2^9 / 5^6 + */ +#define SJA1105_CC_MULT_NUM (1 << 9) +#define SJA1105_CC_MULT_DEM 15625 + +#define ptp_to_sja1105(d) container_of((d), struct sja1105_private, ptp_caps) +#define cc_to_sja1105(d) container_of((d), struct sja1105_private, tstamp_cc) +#define dw_to_sja1105(d) container_of((d), struct sja1105_private, refresh_work) + +struct sja1105_ptp_cmd { + u64 resptp; /* reset */ +}; + +int sja1105_get_ts_info(struct dsa_switch *ds, int port, + struct ethtool_ts_info *info) +{ + struct sja1105_private *priv = ds->priv; + + /* Called during cleanup */ + if (!priv->clock) + return -ENODEV; + + info->so_timestamping = SOF_TIMESTAMPING_TX_HARDWARE | + SOF_TIMESTAMPING_RX_HARDWARE | + SOF_TIMESTAMPING_RAW_HARDWARE; + info->tx_types = (1 << HWTSTAMP_TX_OFF) | + (1 << HWTSTAMP_TX_ON); + info->rx_filters = (1 << HWTSTAMP_FILTER_NONE) | + (1 << HWTSTAMP_FILTER_PTP_V2_L2_EVENT); + info->phc_index = ptp_clock_index(priv->clock); + return 0; +} + +int sja1105et_ptp_cmd(const void *ctx, const void *data) +{ + const struct sja1105_ptp_cmd *cmd = data; + const struct sja1105_private *priv = ctx; + const struct sja1105_regs *regs = priv->info->regs; + const int size = SJA1105_SIZE_PTP_CMD; + u8 buf[SJA1105_SIZE_PTP_CMD] = {0}; + /* No need to keep this as part of the structure */ + u64 valid = 1; + + sja1105_pack(buf, &valid, 31, 31, size); + sja1105_pack(buf, &cmd->resptp, 2, 2, size); + + return sja1105_spi_send_packed_buf(priv, SPI_WRITE, regs->ptp_control, + buf, SJA1105_SIZE_PTP_CMD); +} + +int sja1105pqrs_ptp_cmd(const void *ctx, const void *data) +{ + const struct sja1105_ptp_cmd *cmd = data; + const struct sja1105_private *priv = ctx; + const struct sja1105_regs *regs = priv->info->regs; + const int size = SJA1105_SIZE_PTP_CMD; + u8 buf[SJA1105_SIZE_PTP_CMD] = {0}; + /* No need to keep this as part of the structure */ + u64 valid = 1; + + sja1105_pack(buf, &valid, 31, 31, size); + sja1105_pack(buf, &cmd->resptp, 3, 3, size); + + return sja1105_spi_send_packed_buf(priv, SPI_WRITE, regs->ptp_control, + buf, SJA1105_SIZE_PTP_CMD); +} + +/* The switch returns partial timestamps (24 bits for SJA1105 E/T, which wrap + * around in 0.135 seconds, and 32 bits for P/Q/R/S, wrapping around in 34.35 + * seconds). + * + * This receives the RX or TX MAC timestamps, provided by hardware as + * the lower bits of the cycle counter, sampled at the time the timestamp was + * collected. + * + * To reconstruct into a full 64-bit-wide timestamp, the cycle counter is + * read and the high-order bits are filled in. + * + * Must be called within one wraparound period of the partial timestamp since + * it was generated by the MAC. + */ +u64 sja1105_tstamp_reconstruct(struct sja1105_private *priv, u64 now, + u64 ts_partial) +{ + u64 partial_tstamp_mask = CYCLECOUNTER_MASK(priv->info->ptp_ts_bits); + u64 ts_reconstructed; + + ts_reconstructed = (now & ~partial_tstamp_mask) | ts_partial; + + /* Check lower bits of current cycle counter against the timestamp. + * If the current cycle counter is lower than the partial timestamp, + * then wraparound surely occurred and must be accounted for. + */ + if ((now & partial_tstamp_mask) <= ts_partial) + ts_reconstructed -= (partial_tstamp_mask + 1); + + return ts_reconstructed; +} + +/* Reads the SPI interface for an egress timestamp generated by the switch + * for frames sent using management routes. + * + * SJA1105 E/T layout of the 4-byte SPI payload: + * + * 31 23 15 7 0 + * | | | | | + * +-----+-----+-----+ ^ + * ^ | + * | | + * 24-bit timestamp Update bit + * + * + * SJA1105 P/Q/R/S layout of the 8-byte SPI payload: + * + * 31 23 15 7 0 63 55 47 39 32 + * | | | | | | | | | | + * ^ +-----+-----+-----+-----+ + * | ^ + * | | + * Update bit 32-bit timestamp + * + * Notice that the update bit is in the same place. + * To have common code for E/T and P/Q/R/S for reading the timestamp, + * we need to juggle with the offset and the bit indices. + */ +int sja1105_ptpegr_ts_poll(struct sja1105_private *priv, int port, u64 *ts) +{ + const struct sja1105_regs *regs = priv->info->regs; + int tstamp_bit_start, tstamp_bit_end; + int timeout = 10; + u8 packed_buf[8]; + u64 update; + int rc; + + do { + rc = sja1105_spi_send_packed_buf(priv, SPI_READ, + regs->ptpegr_ts[port], + packed_buf, + priv->info->ptpegr_ts_bytes); + if (rc < 0) + return rc; + + sja1105_unpack(packed_buf, &update, 0, 0, + priv->info->ptpegr_ts_bytes); + if (update) + break; + + usleep_range(10, 50); + } while (--timeout); + + if (!timeout) + return -ETIMEDOUT; + + /* Point the end bit to the second 32-bit word on P/Q/R/S, + * no-op on E/T. + */ + tstamp_bit_end = (priv->info->ptpegr_ts_bytes - 4) * 8; + /* Shift the 24-bit timestamp on E/T to be collected from 31:8. + * No-op on P/Q/R/S. + */ + tstamp_bit_end += 32 - priv->info->ptp_ts_bits; + tstamp_bit_start = tstamp_bit_end + priv->info->ptp_ts_bits - 1; + + *ts = 0; + + sja1105_unpack(packed_buf, ts, tstamp_bit_start, tstamp_bit_end, + priv->info->ptpegr_ts_bytes); + + return 0; +} + +int sja1105_ptp_reset(struct sja1105_private *priv) +{ + struct dsa_switch *ds = priv->ds; + struct sja1105_ptp_cmd cmd = {0}; + int rc; + + mutex_lock(&priv->ptp_lock); + + cmd.resptp = 1; + dev_dbg(ds->dev, "Resetting PTP clock\n"); + rc = priv->info->ptp_cmd(priv, &cmd); + + timecounter_init(&priv->tstamp_tc, &priv->tstamp_cc, + ktime_to_ns(ktime_get_real())); + + mutex_unlock(&priv->ptp_lock); + + return rc; +} + +static int sja1105_ptp_gettime(struct ptp_clock_info *ptp, + struct timespec64 *ts) +{ + struct sja1105_private *priv = ptp_to_sja1105(ptp); + u64 ns; + + mutex_lock(&priv->ptp_lock); + ns = timecounter_read(&priv->tstamp_tc); + mutex_unlock(&priv->ptp_lock); + + *ts = ns_to_timespec64(ns); + + return 0; +} + +static int sja1105_ptp_settime(struct ptp_clock_info *ptp, + const struct timespec64 *ts) +{ + struct sja1105_private *priv = ptp_to_sja1105(ptp); + u64 ns = timespec64_to_ns(ts); + + mutex_lock(&priv->ptp_lock); + timecounter_init(&priv->tstamp_tc, &priv->tstamp_cc, ns); + mutex_unlock(&priv->ptp_lock); + + return 0; +} + +static int sja1105_ptp_adjfine(struct ptp_clock_info *ptp, long scaled_ppm) +{ + struct sja1105_private *priv = ptp_to_sja1105(ptp); + s64 clkrate; + + clkrate = (s64)scaled_ppm * SJA1105_CC_MULT_NUM; + clkrate = div_s64(clkrate, SJA1105_CC_MULT_DEM); + + mutex_lock(&priv->ptp_lock); + + /* Force a readout to update the timer *before* changing its frequency. + * + * This way, its corrected time curve can at all times be modeled + * as a linear "A * x + B" function, where: + * + * - B are past frequency adjustments and offset shifts, all + * accumulated into the cycle_last variable. + * + * - A is the new frequency adjustments we're just about to set. + * + * Reading now makes B accumulate the correct amount of time, + * corrected at the old rate, before changing it. + * + * Hardware timestamps then become simple points on the curve and + * are approximated using the above function. This is still better + * than letting the switch take the timestamps using the hardware + * rate-corrected clock (PTPCLKVAL) - the comparison in this case would + * be that we're shifting the ruler at the same time as we're taking + * measurements with it. + * + * The disadvantage is that it's possible to receive timestamps when + * a frequency adjustment took place in the near past. + * In this case they will be approximated using the new ppb value + * instead of a compound function made of two segments (one at the old + * and the other at the new rate) - introducing some inaccuracy. + */ + timecounter_read(&priv->tstamp_tc); + + priv->tstamp_cc.mult = SJA1105_CC_MULT + clkrate; + + mutex_unlock(&priv->ptp_lock); + + return 0; +} + +static int sja1105_ptp_adjtime(struct ptp_clock_info *ptp, s64 delta) +{ + struct sja1105_private *priv = ptp_to_sja1105(ptp); + + mutex_lock(&priv->ptp_lock); + timecounter_adjtime(&priv->tstamp_tc, delta); + mutex_unlock(&priv->ptp_lock); + + return 0; +} + +static u64 sja1105_ptptsclk_read(const struct cyclecounter *cc) +{ + struct sja1105_private *priv = cc_to_sja1105(cc); + const struct sja1105_regs *regs = priv->info->regs; + u64 ptptsclk = 0; + int rc; + + rc = sja1105_spi_send_int(priv, SPI_READ, regs->ptptsclk, + &ptptsclk, 8); + if (rc < 0) + dev_err_ratelimited(priv->ds->dev, + "failed to read ptp cycle counter: %d\n", + rc); + return ptptsclk; +} + +static void sja1105_ptp_overflow_check(struct work_struct *work) +{ + struct delayed_work *dw = to_delayed_work(work); + struct sja1105_private *priv = dw_to_sja1105(dw); + struct timespec64 ts; + + sja1105_ptp_gettime(&priv->ptp_caps, &ts); + + schedule_delayed_work(&priv->refresh_work, SJA1105_REFRESH_INTERVAL); +} + +static const struct ptp_clock_info sja1105_ptp_caps = { + .owner = THIS_MODULE, + .name = "SJA1105 PHC", + .adjfine = sja1105_ptp_adjfine, + .adjtime = sja1105_ptp_adjtime, + .gettime64 = sja1105_ptp_gettime, + .settime64 = sja1105_ptp_settime, + .max_adj = SJA1105_MAX_ADJ_PPB, +}; + +int sja1105_ptp_clock_register(struct sja1105_private *priv) +{ + struct dsa_switch *ds = priv->ds; + + /* Set up the cycle counter */ + priv->tstamp_cc = (struct cyclecounter) { + .read = sja1105_ptptsclk_read, + .mask = CYCLECOUNTER_MASK(64), + .shift = SJA1105_CC_SHIFT, + .mult = SJA1105_CC_MULT, + }; + mutex_init(&priv->ptp_lock); + INIT_DELAYED_WORK(&priv->refresh_work, sja1105_ptp_overflow_check); + + schedule_delayed_work(&priv->refresh_work, SJA1105_REFRESH_INTERVAL); + + priv->ptp_caps = sja1105_ptp_caps; + + priv->clock = ptp_clock_register(&priv->ptp_caps, ds->dev); + if (IS_ERR_OR_NULL(priv->clock)) + return PTR_ERR(priv->clock); + + return sja1105_ptp_reset(priv); +} + +void sja1105_ptp_clock_unregister(struct sja1105_private *priv) +{ + if (IS_ERR_OR_NULL(priv->clock)) + return; + + cancel_delayed_work_sync(&priv->refresh_work); + ptp_clock_unregister(priv->clock); + priv->clock = NULL; +} |