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Message-ID: <20250614000754.164827-6-hramamurthy@google.com>
Date: Sat, 14 Jun 2025 00:07:51 +0000
From: Harshitha Ramamurthy <hramamurthy@...gle.com>
To: netdev@...r.kernel.org
Cc: davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
pabeni@...hat.com, jeroendb@...gle.com, hramamurthy@...gle.com,
andrew+netdev@...n.ch, willemb@...gle.com, ziweixiao@...gle.com,
pkaligineedi@...gle.com, yyd@...gle.com, joshwash@...gle.com,
shailend@...gle.com, linux@...blig.org, thostet@...gle.com,
jfraker@...gle.com, richardcochran@...il.com, jdamato@...tly.com,
vadim.fedorenko@...ux.dev, horms@...nel.org, linux-kernel@...r.kernel.org
Subject: [PATCH net-next v5 5/8] gve: Add support to query the nic clock
From: Kevin Yang <yyd@...gle.com>
Query the nic clock and store the results. The timestamp delivered
in descriptors has a wraparound time of ~4 seconds so 250ms is chosen
as the sync cadence to provide a balance between performance, and
drift potential when we do start associating host time and nic time.
Leverage PTP's aux_work to query the nic clock periodically.
Signed-off-by: Kevin Yang <yyd@...gle.com>
Signed-off-by: John Fraker <jfraker@...gle.com>
Signed-off-by: Tim Hostetler <thostet@...gle.com>
Signed-off-by: Ziwei Xiao <ziweixiao@...gle.com>
Reviewed-by: Willem de Bruijn <willemb@...gle.com>
Signed-off-by: Harshitha Ramamurthy <hramamurthy@...gle.com>
---
Changes in v5:
- Change to register PTP when initializing the driver and keep it
alive until destroying the driver. (Jakub Kicinski)
Changes in v4:
- release the ptp in the error path of gve_init_clock (Jakub Kicinski)
Changes in v2:
- Utilize the ptp's aux_work instead of delayed_work (Jakub Kicinski,
Vadim Fedorenko)
---
drivers/net/ethernet/google/gve/gve.h | 21 ++++++
drivers/net/ethernet/google/gve/gve_main.c | 7 +-
drivers/net/ethernet/google/gve/gve_ptp.c | 84 +++++++++++++++++++++-
3 files changed, 109 insertions(+), 3 deletions(-)
diff --git a/drivers/net/ethernet/google/gve/gve.h b/drivers/net/ethernet/google/gve/gve.h
index 8d2aa654fd4c..527e17da60bc 100644
--- a/drivers/net/ethernet/google/gve/gve.h
+++ b/drivers/net/ethernet/google/gve/gve.h
@@ -882,6 +882,9 @@ struct gve_priv {
/* True if the device supports reading the nic clock */
bool nic_timestamp_supported;
struct gve_ptp *ptp;
+ struct gve_nic_ts_report *nic_ts_report;
+ dma_addr_t nic_ts_report_bus;
+ u64 last_sync_nic_counter; /* Clock counter from last NIC TS report */
};
enum gve_service_task_flags_bit {
@@ -1261,6 +1264,24 @@ int gve_del_flow_rule(struct gve_priv *priv, struct ethtool_rxnfc *cmd);
int gve_flow_rules_reset(struct gve_priv *priv);
/* RSS config */
int gve_init_rss_config(struct gve_priv *priv, u16 num_queues);
+/* PTP and timestamping */
+#if IS_ENABLED(CONFIG_PTP_1588_CLOCK)
+int gve_clock_nic_ts_read(struct gve_priv *priv);
+int gve_init_clock(struct gve_priv *priv);
+void gve_teardown_clock(struct gve_priv *priv);
+#else /* CONFIG_PTP_1588_CLOCK */
+static inline int gve_clock_nic_ts_read(struct gve_priv *priv)
+{
+ return -EOPNOTSUPP;
+}
+
+static inline int gve_init_clock(struct gve_priv *priv)
+{
+ return 0;
+}
+
+static inline void gve_teardown_clock(struct gve_priv *priv) { }
+#endif /* CONFIG_PTP_1588_CLOCK */
/* report stats handling */
void gve_handle_report_stats(struct gve_priv *priv);
/* exported by ethtool.c */
diff --git a/drivers/net/ethernet/google/gve/gve_main.c b/drivers/net/ethernet/google/gve/gve_main.c
index dc35a23ec47f..bc2f36962ee8 100644
--- a/drivers/net/ethernet/google/gve/gve_main.c
+++ b/drivers/net/ethernet/google/gve/gve_main.c
@@ -619,9 +619,12 @@ static int gve_setup_device_resources(struct gve_priv *priv)
err = gve_alloc_counter_array(priv);
if (err)
goto abort_with_rss_config_cache;
- err = gve_alloc_notify_blocks(priv);
+ err = gve_init_clock(priv);
if (err)
goto abort_with_counter;
+ err = gve_alloc_notify_blocks(priv);
+ if (err)
+ goto abort_with_clock;
err = gve_alloc_stats_report(priv);
if (err)
goto abort_with_ntfy_blocks;
@@ -674,6 +677,8 @@ static int gve_setup_device_resources(struct gve_priv *priv)
gve_free_stats_report(priv);
abort_with_ntfy_blocks:
gve_free_notify_blocks(priv);
+abort_with_clock:
+ gve_teardown_clock(priv);
abort_with_counter:
gve_free_counter_array(priv);
abort_with_rss_config_cache:
diff --git a/drivers/net/ethernet/google/gve/gve_ptp.c b/drivers/net/ethernet/google/gve/gve_ptp.c
index 293f8dd49afe..e96247c9d68d 100644
--- a/drivers/net/ethernet/google/gve/gve_ptp.c
+++ b/drivers/net/ethernet/google/gve/gve_ptp.c
@@ -5,13 +5,52 @@
*/
#include "gve.h"
+#include "gve_adminq.h"
+
+/* Interval to schedule a nic timestamp calibration, 250ms. */
+#define GVE_NIC_TS_SYNC_INTERVAL_MS 250
+
+/* Read the nic timestamp from hardware via the admin queue. */
+int gve_clock_nic_ts_read(struct gve_priv *priv)
+{
+ u64 nic_raw;
+ int err;
+
+ err = gve_adminq_report_nic_ts(priv, priv->nic_ts_report_bus);
+ if (err)
+ return err;
+
+ nic_raw = be64_to_cpu(priv->nic_ts_report->nic_timestamp);
+ WRITE_ONCE(priv->last_sync_nic_counter, nic_raw);
+
+ return 0;
+}
+
+static long gve_ptp_do_aux_work(struct ptp_clock_info *info)
+{
+ const struct gve_ptp *ptp = container_of(info, struct gve_ptp, info);
+ struct gve_priv *priv = ptp->priv;
+ int err;
+
+ if (gve_get_reset_in_progress(priv) || !gve_get_admin_queue_ok(priv))
+ goto out;
+
+ err = gve_clock_nic_ts_read(priv);
+ if (err && net_ratelimit())
+ dev_err(&priv->pdev->dev,
+ "%s read err %d\n", __func__, err);
+
+out:
+ return msecs_to_jiffies(GVE_NIC_TS_SYNC_INTERVAL_MS);
+}
static const struct ptp_clock_info gve_ptp_caps = {
.owner = THIS_MODULE,
.name = "gve clock",
+ .do_aux_work = gve_ptp_do_aux_work,
};
-static int __maybe_unused gve_ptp_init(struct gve_priv *priv)
+static int gve_ptp_init(struct gve_priv *priv)
{
struct gve_ptp *ptp;
int err;
@@ -44,7 +83,7 @@ static int __maybe_unused gve_ptp_init(struct gve_priv *priv)
return err;
}
-static void __maybe_unused gve_ptp_release(struct gve_priv *priv)
+static void gve_ptp_release(struct gve_priv *priv)
{
struct gve_ptp *ptp = priv->ptp;
@@ -57,3 +96,44 @@ static void __maybe_unused gve_ptp_release(struct gve_priv *priv)
kfree(ptp);
priv->ptp = NULL;
}
+
+int gve_init_clock(struct gve_priv *priv)
+{
+ int err;
+
+ if (!priv->nic_timestamp_supported)
+ return 0;
+
+ err = gve_ptp_init(priv);
+ if (err)
+ return err;
+
+ priv->nic_ts_report =
+ dma_alloc_coherent(&priv->pdev->dev,
+ sizeof(struct gve_nic_ts_report),
+ &priv->nic_ts_report_bus,
+ GFP_KERNEL);
+ if (!priv->nic_ts_report) {
+ dev_err(&priv->pdev->dev, "%s dma alloc error\n", __func__);
+ err = -ENOMEM;
+ goto release_ptp;
+ }
+
+ return 0;
+
+release_ptp:
+ gve_ptp_release(priv);
+ return err;
+}
+
+void gve_teardown_clock(struct gve_priv *priv)
+{
+ gve_ptp_release(priv);
+
+ if (priv->nic_ts_report) {
+ dma_free_coherent(&priv->pdev->dev,
+ sizeof(struct gve_nic_ts_report),
+ priv->nic_ts_report, priv->nic_ts_report_bus);
+ priv->nic_ts_report = NULL;
+ }
+}
--
2.50.0.rc1.591.g9c95f17f64-goog
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