[PATCH v3 net-next 6/7] net: ena: Add error bound to PHC communication layer

[Arthur Kiyanovski <akiyano@amazon.com>]

Extend the ENA PHC communication layer to retrieve error bound from
the device.

Update ena_com_phc_get_timestamp() to retrieve error_bound alongside
timestamps.
Add error handling and statistics for error_bound retrieval failures.

Signed-off-by: Amit Bernstein <amitbern@amazon.com>
Signed-off-by: Arthur Kiyanovski <akiyano@amazon.com>
---
 .../device_drivers/ethernet/amazon/ena.rst    |  2 ++
 drivers/net/ethernet/amazon/ena/ena_com.c     | 36 ++++++++++++-------
 drivers/net/ethernet/amazon/ena/ena_com.h     |  5 ++-
 drivers/net/ethernet/amazon/ena/ena_debugfs.c |  3 ++
 drivers/net/ethernet/amazon/ena/ena_phc.c     |  3 +-
 5 files changed, 34 insertions(+), 15 deletions(-)

diff --git a/Documentation/networking/device_drivers/ethernet/amazon/ena.rst b/Documentation/networking/device_drivers/ethernet/amazon/ena.rst
index 14784a0..ce9ba84 100644
--- a/Documentation/networking/device_drivers/ethernet/amazon/ena.rst
+++ b/Documentation/networking/device_drivers/ethernet/amazon/ena.rst
@@ -306,6 +306,8 @@ PHC errors must remain below 1% of all PHC requests to maintain the desired leve
 **phc_err_dv**      | Number of failed get time attempts due to device errors (entering into block state).
 **phc_err_ts**      | Number of failed get time attempts due to timestamp errors (entering into block state),
                     | This occurs if driver exceeded the request limit or device received an invalid timestamp.
+**phc_err_eb**      | Number of failed get time attempts due to error bound errors (entering into block state),
+                    | This occurs if device received an excessively high or invalid error bound.
 =================   ======================================================
 
 PHC timeouts:
diff --git a/drivers/net/ethernet/amazon/ena/ena_com.c b/drivers/net/ethernet/amazon/ena/ena_com.c
index 2579104..832c4c1 100644
--- a/drivers/net/ethernet/amazon/ena/ena_com.c
+++ b/drivers/net/ethernet/amazon/ena/ena_com.c
@@ -45,7 +45,8 @@
 #define ENA_PHC_DEFAULT_EXPIRE_TIMEOUT_USEC 10
 #define ENA_PHC_DEFAULT_BLOCK_TIMEOUT_USEC 1000
 #define ENA_PHC_REQ_ID_OFFSET 0xDEAD
-#define ENA_PHC_ERROR_FLAGS (ENA_ADMIN_PHC_ERROR_FLAG_TIMESTAMP)
+#define ENA_PHC_ERROR_FLAGS (ENA_ADMIN_PHC_ERROR_FLAG_TIMESTAMP | \
+			     ENA_ADMIN_PHC_ERROR_FLAG_ERROR_BOUND)
 
 /*****************************************************************************/
 /*****************************************************************************/
@@ -1726,7 +1727,7 @@ int ena_com_phc_config(struct ena_com_dev *ena_dev)
 	if (phc->expire_timeout_usec > phc->block_timeout_usec)
 		phc->expire_timeout_usec = phc->block_timeout_usec;
 
-	/* Prepare PHC feature command */
+	/* Prepare PHC config feature command */
 	memset(&set_feat_cmd, 0x0, sizeof(set_feat_cmd));
 	set_feat_cmd.aq_common_descriptor.opcode = ENA_ADMIN_SET_FEATURE;
 	set_feat_cmd.feat_common.feature_id = ENA_ADMIN_PHC_CONFIG;
@@ -1781,7 +1782,8 @@ void ena_com_phc_destroy(struct ena_com_dev *ena_dev)
 	phc->virt_addr = NULL;
 }
 
-int ena_com_phc_get_timestamp(struct ena_com_dev *ena_dev, u64 *timestamp)
+int ena_com_phc_get_timestamp(struct ena_com_dev *ena_dev, u64 *timestamp,
+			      u32 *error_bound)
 {
 	const ktime_t zero_system_time = ktime_set(0, 0);
 	struct ena_com_phc_info *phc = &ena_dev->phc;
@@ -1828,6 +1830,8 @@ int ena_com_phc_get_timestamp(struct ena_com_dev *ena_dev, u64 *timestamp)
 			 * a PHC error, this occurs if device:
 			 * - exceeded the get time request limit
 			 * - received an invalid timestamp
+			 * - received an excessively high error bound
+			 * - received an invalid error bound
 			 */
 			netdev_err(ena_dev->net_device,
 				   "PHC get time request 0x%x failed (error 0x%x)\n",
@@ -1835,9 +1839,11 @@ int ena_com_phc_get_timestamp(struct ena_com_dev *ena_dev, u64 *timestamp)
 				   resp->error_flags);
 			phc->stats.phc_err_ts += !!(resp->error_flags &
 				ENA_ADMIN_PHC_ERROR_FLAG_TIMESTAMP);
+			phc->stats.phc_err_eb += !!(resp->error_flags &
+				ENA_ADMIN_PHC_ERROR_FLAG_ERROR_BOUND);
 		} else {
 			/* Device updated req_id during blocking time
-			 * with valid timestamp
+			 * with valid timestamp and error bound
 			 */
 			phc->stats.phc_exp++;
 		}
@@ -1864,9 +1870,9 @@ int ena_com_phc_get_timestamp(struct ena_com_dev *ena_dev, u64 *timestamp)
 	/* Stalling until the device updates req_id */
 	while (1) {
 		if (unlikely(ktime_after(ktime_get(), expire_time))) {
-			/* Gave up waiting for updated req_id, PHC enters into
-			 * blocked state until passing blocking time,
-			 * during this time any get PHC timestamp will fail with
+			/* Gave up waiting for updated req_id,
+			 * PHC enters into blocked state until passing blocking
+			 * time, during this time, any request will fail with
 			 * device busy error
 			 */
 			ret = -EBUSY;
@@ -1882,14 +1888,15 @@ int ena_com_phc_get_timestamp(struct ena_com_dev *ena_dev, u64 *timestamp)
 		}
 
 		/* req_id was updated by the device which indicates that
-		 * PHC timestamp and error_flags are updated too,
-		 * checking errors before retrieving timestamp
+		 * PHC timestamp, error_bound and error_flags are updated too,
+		 * checking error flags before retrieving timestamp and
+		 * error_bound values
 		 */
 		if (unlikely(resp->error_flags & ENA_PHC_ERROR_FLAGS)) {
-			/* Retrieved invalid PHC timestamp, PHC enters into
-			 * blocked state until passing blocking time,
-			 * during this time any get PHC timestamp requests
-			 * will fail with device busy error
+			/* Retrieved timestamp or error bound errors,
+			 * PHC enters into blocked state until passing blocking
+			 * time, during this time, any request will fail with
+			 * device busy error
 			 */
 			ret = -EBUSY;
 			break;
@@ -1897,12 +1904,15 @@ int ena_com_phc_get_timestamp(struct ena_com_dev *ena_dev, u64 *timestamp)
 
 		/* PHC timestamp value is returned to the caller */
 		*timestamp = resp->timestamp;
+		if (error_bound)
+			*error_bound = resp->error_bound;
 
 		/* Update statistic on valid PHC timestamp retrieval */
 		phc->stats.phc_cnt++;
 
 		/* This indicates PHC state is active */
 		phc->system_time = zero_system_time;
+
 		break;
 	}
 
diff --git a/drivers/net/ethernet/amazon/ena/ena_com.h b/drivers/net/ethernet/amazon/ena/ena_com.h
index 64df2c4..fcbff1a 100644
--- a/drivers/net/ethernet/amazon/ena/ena_com.h
+++ b/drivers/net/ethernet/amazon/ena/ena_com.h
@@ -216,6 +216,7 @@ struct ena_com_stats_phc {
 	u64 phc_skp;
 	u64 phc_err_dv;
 	u64 phc_err_ts;
+	u64 phc_err_eb;
 };
 
 struct ena_com_admin_queue {
@@ -462,9 +463,11 @@ void ena_com_phc_destroy(struct ena_com_dev *ena_dev);
 /* ena_com_phc_get_timestamp - Retrieve PHC timestamp
  * @ena_dev: ENA communication layer struct
  * @timestamp: Retrieved PHC timestamp
+ * @error_bound: maximum possible deviation of the timestamp (nanosecond)
  * @return - 0 on success, negative value on failure
  */
-int ena_com_phc_get_timestamp(struct ena_com_dev *ena_dev, u64 *timestamp);
+int ena_com_phc_get_timestamp(struct ena_com_dev *ena_dev, u64 *timestamp,
+			      u32 *error_bound);
 
 /* ena_com_set_mmio_read_mode - Enable/disable the indirect mmio reg read mechanism
  * @ena_dev: ENA communication layer struct
diff --git a/drivers/net/ethernet/amazon/ena/ena_debugfs.c b/drivers/net/ethernet/amazon/ena/ena_debugfs.c
index 46ed809..db9d184 100644
--- a/drivers/net/ethernet/amazon/ena/ena_debugfs.c
+++ b/drivers/net/ethernet/amazon/ena/ena_debugfs.c
@@ -32,6 +32,9 @@ static int phc_stats_show(struct seq_file *file, void *priv)
 	seq_printf(file,
 		   "phc_err_ts: %llu\n",
 		   adapter->ena_dev->phc.stats.phc_err_ts);
+	seq_printf(file,
+		   "phc_err_eb: %llu\n",
+		   adapter->ena_dev->phc.stats.phc_err_eb);
 
 	return 0;
 }
diff --git a/drivers/net/ethernet/amazon/ena/ena_phc.c b/drivers/net/ethernet/amazon/ena/ena_phc.c
index c2a3ff1..2bcb5af 100644
--- a/drivers/net/ethernet/amazon/ena/ena_phc.c
+++ b/drivers/net/ethernet/amazon/ena/ena_phc.c
@@ -40,7 +40,8 @@ static int ena_phc_gettimex64(struct ptp_clock_info *clock_info,
 	ptp_read_system_prets(sts);
 
 	rc = ena_com_phc_get_timestamp(phc_info->adapter->ena_dev,
-				       &timestamp_nsec);
+				       &timestamp_nsec,
+				       NULL);
 
 	ptp_read_system_postts(sts);
 
-- 
2.47.3