From: Rahul Rameshbabu <rrameshbabu@xxxxxxxxxx>
Expose Precision Time Measurement support through related PTP ioctl.
The performance of PTM on ConnectX-7 was evaluated using both real-time
(RTC) and free-running (FRC) clocks under traffic and no traffic
conditions. Tests with phc2sys measured the maximum offset values at a 50Hz
rate, with and without PTM.
Results:
1. No traffic
+-----+--------+--------+
| | No-PTM | PTM |
+-----+--------+--------+
| FRC | 125 ns | <29 ns |
+-----+--------+--------+
| RTC | 248 ns | <34 ns |
+-----+--------+--------+
2. With traffic
+-----+--------+--------+
| | No-PTM | PTM |
+-----+--------+--------+
| FRC | 254 ns | <40 ns |
+-----+--------+--------+
| RTC | 255 ns | <45 ns |
+-----+--------+--------+
Signed-off-by: Rahul Rameshbabu <rrameshbabu@xxxxxxxxxx>
Co-developed-by: Carolina Jubran <cjubran@xxxxxxxxxx>
Signed-off-by: Carolina Jubran <cjubran@xxxxxxxxxx>
Signed-off-by: Tariq Toukan <tariqt@xxxxxxxxxx>
---
.../ethernet/mellanox/mlx5/core/lib/clock.c | 91 +++++++++++++++++++
1 file changed, 91 insertions(+)
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c b/drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c
index 0361741632a6..b306ae79bf97 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c
@@ -38,6 +38,10 @@
#include "lib/eq.h"
#include "en.h"
#include "clock.h"
+#ifdef CONFIG_X86
+#include <linux/timekeeping.h>
+#include <linux/cpufeature.h>
+#endif /* CONFIG_X86 */
enum {
MLX5_PIN_MODE_IN = 0x0,
@@ -148,6 +152,87 @@ static int mlx5_set_mtutc(struct mlx5_core_dev *dev, u32 *mtutc, u32 size)
MLX5_REG_MTUTC, 0, 1);
}
+#ifdef CONFIG_X86
+static bool mlx5_is_ptm_source_time_available(struct mlx5_core_dev *dev)
+{
+ u32 out[MLX5_ST_SZ_DW(mtptm_reg)] = {0};
+ u32 in[MLX5_ST_SZ_DW(mtptm_reg)] = {0};
+ int err;
+
+ if (!MLX5_CAP_MCAM_REG3(dev, mtptm))
+ return false;
+
+ err = mlx5_core_access_reg(dev, in, sizeof(in), out, sizeof(out), MLX5_REG_MTPTM,
+ 0, 0);
+ if (err)
+ return false;
+
+ return !!MLX5_GET(mtptm_reg, out, psta);
+}
+
+static int mlx5_mtctr_syncdevicetime(ktime_t *device_time,
+ struct system_counterval_t *sys_counterval,
+ void *ctx)
+{
+ u32 out[MLX5_ST_SZ_DW(mtctr_reg)] = {0};
+ u32 in[MLX5_ST_SZ_DW(mtctr_reg)] = {0};
+ struct mlx5_core_dev *mdev = ctx;
+ bool real_time_mode;
+ u64 host, device;
+ int err;
+
+ real_time_mode = mlx5_real_time_mode(mdev);
+
+ MLX5_SET(mtctr_reg, in, first_clock_timestamp_request,
+ MLX5_MTCTR_REQUEST_PTM_ROOT_CLOCK);
+ MLX5_SET(mtctr_reg, in, second_clock_timestamp_request,
+ real_time_mode ? MLX5_MTCTR_REQUEST_REAL_TIME_CLOCK :
+ MLX5_MTCTR_REQUEST_FREE_RUNNING_COUNTER);
+
+ err = mlx5_core_access_reg(mdev, in, sizeof(in), out, sizeof(out), MLX5_REG_MTCTR,
+ 0, 0);
+ if (err)
+ return err;
+
+ if (!MLX5_GET(mtctr_reg, out, first_clock_valid) ||
+ !MLX5_GET(mtctr_reg, out, second_clock_valid))
+ return -EINVAL;
+
+ host = MLX5_GET64(mtctr_reg, out, first_clock_timestamp);
+ *sys_counterval = (struct system_counterval_t) {
+ .cycles = host,
+ .cs_id = CSID_X86_ART,
+ .use_nsecs = true,
+ };
+
+ device = MLX5_GET64(mtctr_reg, out, second_clock_timestamp);
+ if (real_time_mode)
+ *device_time = ns_to_ktime(REAL_TIME_TO_NS(device >> 32, device & U32_MAX));
+ else
+ *device_time = mlx5_timecounter_cyc2time(&mdev->clock, device);
+
+ return 0;
+}
+
+static int mlx5_ptp_getcrosststamp(struct ptp_clock_info *ptp,
+ struct system_device_crosststamp *cts)
+{
+ struct mlx5_clock *clock = container_of(ptp, struct mlx5_clock, ptp_info);
+ struct system_time_snapshot history_begin = {0};
+ struct mlx5_core_dev *mdev;
+
+ mdev = container_of(clock, struct mlx5_core_dev, clock);
+
+ if (!mlx5_is_ptm_source_time_available(mdev))
+ return -EBUSY;
+
+ ktime_get_snapshot(&history_begin);
+
+ return get_device_system_crosststamp(mlx5_mtctr_syncdevicetime, mdev,
+ &history_begin, cts);
+}
+#endif /* CONFIG_X86 */
+
static u64 mlx5_read_time(struct mlx5_core_dev *dev,
struct ptp_system_timestamp *sts,
bool real_time)
@@ -1034,6 +1119,12 @@ static void mlx5_init_timer_clock(struct mlx5_core_dev *mdev)
if (MLX5_CAP_MCAM_REG(mdev, mtutc))
mlx5_init_timer_max_freq_adjustment(mdev);
+#ifdef CONFIG_X86
+ if (MLX5_CAP_MCAM_REG3(mdev, mtptm) &&
+ MLX5_CAP_MCAM_REG3(mdev, mtctr) && boot_cpu_has(X86_FEATURE_ART))
+ clock->ptp_info.getcrosststamp = mlx5_ptp_getcrosststamp;
+#endif /* CONFIG_X86 */
+
mlx5_timecounter_init(mdev);
mlx5_init_clock_info(mdev);
mlx5_init_overflow_period(clock);
--
2.44.0
