1 files changed, 303 insertions, 0 deletions
diff --git a/drivers/net/ethernet/meta/fbnic/fbnic_time.c b/drivers/net/ethernet/meta/fbnic/fbnic_time.c
new file mode 100644
index 000000000000..39d99677b71e
--- /dev/null
+++ b/drivers/net/ethernet/meta/fbnic/fbnic_time.c
@@ -0,0 +1,303 @@
+// 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);
+}