--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) Meta Platforms, Inc. and affiliates. */
+
+#include <linux/bitfield.h>
+#include <linux/jiffies.h>
+#include <linux/limits.h>
+#include <linux/ptp_clock_kernel.h>
+#include <linux/timer.h>
+
+#include "fbnic.h"
+#include "fbnic_csr.h"
+#include "fbnic_netdev.h"
+
+/* FBNIC timing & PTP implementation
+ * Datapath uses truncated 40b timestamps for scheduling and event reporting.
+ * We need to promote those to full 64b, hence we periodically cache the top
+ * 32bit of the HW time counter. Since this makes our time reporting non-atomic
+ * we leave the HW clock free running and adjust time offsets in SW as needed.
+ * Time offset is 64bit - we need a seq counter for 32bit machines.
+ * Time offset and the cache of top bits are independent so we don't need
+ * a coherent snapshot of both - READ_ONCE()/WRITE_ONCE() + writer side lock
+ * are enough.
+ */
+
+/* Period of refresh of top bits of timestamp, give ourselves a 8x margin.
+ * This should translate to once a minute.
+ * The use of nsecs_to_jiffies() should be safe for a <=40b nsec value.
+ */
+#define FBNIC_TS_HIGH_REFRESH_JIF nsecs_to_jiffies((1ULL << 40) / 16)
+
+static struct fbnic_dev *fbnic_from_ptp_info(struct ptp_clock_info *ptp)
+{
+ return container_of(ptp, struct fbnic_dev, ptp_info);
+}
+
+/* This function is "slow" because we could try guessing which high part
+ * is correct based on low instead of re-reading, and skip reading @hi
+ * twice altogether if @lo is far enough from 0.
+ */
+static u64 __fbnic_time_get_slow(struct fbnic_dev *fbd)
+{
+ u32 hi, lo;
+
+ lockdep_assert_held(&fbd->time_lock);
+
+ do {
+ hi = fbnic_rd32(fbd, FBNIC_PTP_CTR_VAL_HI);
+ lo = fbnic_rd32(fbd, FBNIC_PTP_CTR_VAL_LO);
+ } while (hi != fbnic_rd32(fbd, FBNIC_PTP_CTR_VAL_HI));
+
+ return (u64)hi << 32 | lo;
+}
+
+static void __fbnic_time_set_addend(struct fbnic_dev *fbd, u64 addend)
+{
+ lockdep_assert_held(&fbd->time_lock);
+
+ fbnic_wr32(fbd, FBNIC_PTP_ADD_VAL_NS,
+ FIELD_PREP(FBNIC_PTP_ADD_VAL_NS_MASK, addend >> 32));
+ fbnic_wr32(fbd, FBNIC_PTP_ADD_VAL_SUBNS, (u32)addend);
+}
+
+static void fbnic_ptp_fresh_check(struct fbnic_dev *fbd)
+{
+ if (time_is_after_jiffies(fbd->last_read +
+ FBNIC_TS_HIGH_REFRESH_JIF * 3 / 2))
+ return;
+
+ dev_warn(fbd->dev, "NIC timestamp refresh stall, delayed by %lu sec\n",
+ (jiffies - fbd->last_read - FBNIC_TS_HIGH_REFRESH_JIF) / HZ);
+}
+
+static void fbnic_ptp_refresh_time(struct fbnic_dev *fbd, struct fbnic_net *fbn)
+{
+ unsigned long flags;
+ u32 hi;
+
+ spin_lock_irqsave(&fbd->time_lock, flags);
+ hi = fbnic_rd32(fbn->fbd, FBNIC_PTP_CTR_VAL_HI);
+ if (!fbnic_present(fbd))
+ goto out; /* Don't bother handling, reset is pending */
+ /* Let's keep high cached value a bit lower to avoid race with
+ * incoming timestamps. The logic in fbnic_ts40_to_ns() will
+ * take care of overflow in this case. It will make cached time
+ * ~1 minute lower and incoming timestamp will always be later
+ * then cached time.
+ */
+ WRITE_ONCE(fbn->time_high, hi - 16);
+ fbd->last_read = jiffies;
+ out:
+ spin_unlock_irqrestore(&fbd->time_lock, flags);
+}
+
+static long fbnic_ptp_do_aux_work(struct ptp_clock_info *ptp)
+{
+ struct fbnic_dev *fbd = fbnic_from_ptp_info(ptp);
+ struct fbnic_net *fbn;
+
+ fbn = netdev_priv(fbd->netdev);
+
+ fbnic_ptp_fresh_check(fbd);
+ fbnic_ptp_refresh_time(fbd, fbn);
+
+ return FBNIC_TS_HIGH_REFRESH_JIF;
+}
+
+static int fbnic_ptp_adjfine(struct ptp_clock_info *ptp, long scaled_ppm)
+{
+ struct fbnic_dev *fbd = fbnic_from_ptp_info(ptp);
+ u64 addend, dclk_period;
+ unsigned long flags;
+
+ /* d_clock is 600 MHz; which in Q16.32 fixed point ns is: */
+ dclk_period = (((u64)1000000000) << 32) / FBNIC_CLOCK_FREQ;
+ addend = adjust_by_scaled_ppm(dclk_period, scaled_ppm);
+
+ spin_lock_irqsave(&fbd->time_lock, flags);
+ __fbnic_time_set_addend(fbd, addend);
+ fbnic_wr32(fbd, FBNIC_PTP_ADJUST, FBNIC_PTP_ADJUST_ADDEND_SET);
+
+ /* Flush, make sure FBNIC_PTP_ADD_VAL_* is stable for at least 4 clks */
+ fbnic_rd32(fbd, FBNIC_PTP_SPARE);
+ spin_unlock_irqrestore(&fbd->time_lock, flags);
+
+ return fbnic_present(fbd) ? 0 : -EIO;
+}
+
+static int fbnic_ptp_adjtime(struct ptp_clock_info *ptp, s64 delta)
+{
+ struct fbnic_dev *fbd = fbnic_from_ptp_info(ptp);
+ struct fbnic_net *fbn;
+ unsigned long flags;
+
+ fbn = netdev_priv(fbd->netdev);
+
+ spin_lock_irqsave(&fbd->time_lock, flags);
+ u64_stats_update_begin(&fbn->time_seq);
+ WRITE_ONCE(fbn->time_offset, READ_ONCE(fbn->time_offset) + delta);
+ u64_stats_update_end(&fbn->time_seq);
+ spin_unlock_irqrestore(&fbd->time_lock, flags);
+
+ return 0;
+}
+
+static int
+fbnic_ptp_gettimex64(struct ptp_clock_info *ptp, struct timespec64 *ts,
+ struct ptp_system_timestamp *sts)
+{
+ struct fbnic_dev *fbd = fbnic_from_ptp_info(ptp);
+ struct fbnic_net *fbn;
+ unsigned long flags;
+ u64 time_ns;
+ u32 hi, lo;
+
+ fbn = netdev_priv(fbd->netdev);
+
+ spin_lock_irqsave(&fbd->time_lock, flags);
+
+ do {
+ hi = fbnic_rd32(fbd, FBNIC_PTP_CTR_VAL_HI);
+ ptp_read_system_prets(sts);
+ lo = fbnic_rd32(fbd, FBNIC_PTP_CTR_VAL_LO);
+ ptp_read_system_postts(sts);
+ /* Similarly to comment above __fbnic_time_get_slow()
+ * - this can be optimized if needed.
+ */
+ } while (hi != fbnic_rd32(fbd, FBNIC_PTP_CTR_VAL_HI));
+
+ time_ns = ((u64)hi << 32 | lo) + fbn->time_offset;
+ spin_unlock_irqrestore(&fbd->time_lock, flags);
+
+ if (!fbnic_present(fbd))
+ return -EIO;
+
+ *ts = ns_to_timespec64(time_ns);
+
+ return 0;
+}
+
+static int
+fbnic_ptp_settime64(struct ptp_clock_info *ptp, const struct timespec64 *ts)
+{
+ struct fbnic_dev *fbd = fbnic_from_ptp_info(ptp);
+ struct fbnic_net *fbn;
+ unsigned long flags;
+ u64 dev_ns, host_ns;
+ int ret;
+
+ fbn = netdev_priv(fbd->netdev);
+
+ host_ns = timespec64_to_ns(ts);
+
+ spin_lock_irqsave(&fbd->time_lock, flags);
+
+ dev_ns = __fbnic_time_get_slow(fbd);
+
+ if (fbnic_present(fbd)) {
+ u64_stats_update_begin(&fbn->time_seq);
+ WRITE_ONCE(fbn->time_offset, host_ns - dev_ns);
+ u64_stats_update_end(&fbn->time_seq);
+ ret = 0;
+ } else {
+ ret = -EIO;
+ }
+ spin_unlock_irqrestore(&fbd->time_lock, flags);
+
+ return ret;
+}
+
+static const struct ptp_clock_info fbnic_ptp_info = {
+ .owner = THIS_MODULE,
+ /* 1,000,000,000 - 1 PPB to ensure increment is positive
+ * after max negative adjustment.
+ */
+ .max_adj = 999999999,
+ .do_aux_work = fbnic_ptp_do_aux_work,
+ .adjfine = fbnic_ptp_adjfine,
+ .adjtime = fbnic_ptp_adjtime,
+ .gettimex64 = fbnic_ptp_gettimex64,
+ .settime64 = fbnic_ptp_settime64,
+};
+
+static void fbnic_ptp_reset(struct fbnic_dev *fbd)
+{
+ struct fbnic_net *fbn = netdev_priv(fbd->netdev);
+ u64 dclk_period;
+
+ fbnic_wr32(fbd, FBNIC_PTP_CTRL,
+ FBNIC_PTP_CTRL_EN |
+ FIELD_PREP(FBNIC_PTP_CTRL_TICK_IVAL, 1));
+
+ /* d_clock is 600 MHz; which in Q16.32 fixed point ns is: */
+ dclk_period = (((u64)1000000000) << 32) / FBNIC_CLOCK_FREQ;
+
+ __fbnic_time_set_addend(fbd, dclk_period);
+
+ fbnic_wr32(fbd, FBNIC_PTP_INIT_HI, 0);
+ fbnic_wr32(fbd, FBNIC_PTP_INIT_LO, 0);
+
+ fbnic_wr32(fbd, FBNIC_PTP_ADJUST, FBNIC_PTP_ADJUST_INIT);
+
+ fbnic_wr32(fbd, FBNIC_PTP_CTRL,
+ FBNIC_PTP_CTRL_EN |
+ FBNIC_PTP_CTRL_TQS_OUT_EN |
+ FIELD_PREP(FBNIC_PTP_CTRL_MAC_OUT_IVAL, 3) |
+ FIELD_PREP(FBNIC_PTP_CTRL_TICK_IVAL, 1));
+
+ fbnic_rd32(fbd, FBNIC_PTP_SPARE);
+
+ fbn->time_offset = 0;
+ fbn->time_high = 0;
+}
+
+void fbnic_time_init(struct fbnic_net *fbn)
+{
+ /* This is not really a statistic, but the lockng primitive fits
+ * our usecase perfectly, we need an atomic 8 bytes READ_ONCE() /
+ * WRITE_ONCE() behavior.
+ */
+ u64_stats_init(&fbn->time_seq);
+}
+
+int fbnic_time_start(struct fbnic_net *fbn)
+{
+ fbnic_ptp_refresh_time(fbn->fbd, fbn);
+ /* Assume that fbnic_ptp_do_aux_work() will never be called if not
+ * scheduled here
+ */
+ return ptp_schedule_worker(fbn->fbd->ptp, FBNIC_TS_HIGH_REFRESH_JIF);
+}
+
+void fbnic_time_stop(struct fbnic_net *fbn)
+{
+ ptp_cancel_worker_sync(fbn->fbd->ptp);
+ fbnic_ptp_fresh_check(fbn->fbd);
+}
+
+int fbnic_ptp_setup(struct fbnic_dev *fbd)
+{
+ struct device *dev = fbd->dev;
+ unsigned long flags;
+
+ spin_lock_init(&fbd->time_lock);
+
+ spin_lock_irqsave(&fbd->time_lock, flags); /* Appease lockdep */
+ fbnic_ptp_reset(fbd);
+ spin_unlock_irqrestore(&fbd->time_lock, flags);
+
+ memcpy(&fbd->ptp_info, &fbnic_ptp_info, sizeof(fbnic_ptp_info));
+
+ fbd->ptp = ptp_clock_register(&fbd->ptp_info, dev);
+ if (IS_ERR(fbd->ptp))
+ dev_err(dev, "Failed to register PTP: %pe\n", fbd->ptp);
+
+ return PTR_ERR_OR_ZERO(fbd->ptp);
+}
+
+void fbnic_ptp_destroy(struct fbnic_dev *fbd)
+{
+ if (!fbd->ptp)
+ return;
+ ptp_clock_unregister(fbd->ptp);
+}
projects / thirdparty / linux.git / commitdiff
