Subject: [net-next V2 10/13] net/mlx5: Convert scaled ppm values outside the s32 range for PHC frequency adjustments

From: Saeed Mahameed <[email-masked]>
Date: Wed, 15 Nov 2023 11:36:46 -0800

From: Rahul Rameshbabu <[email-masked]>

Represent scaled ppm as ppb to the device when the value in scaled ppm is
not representable as a 32-bit signed integer. mlx5 devices only support a
32-bit field for the frequency adjustment value in units of either scaled
ppm or ppb.

Since mlx5 devices only support a 32-bit field for the frequency adjustment
value independent of unit used, limit the maximum frequency adjustment to
S32_MAX ppb.

Signed-off-by: Rahul Rameshbabu <[email-masked]>
Reviewed-by: Tariq Toukan <[email-masked]>
Signed-off-by: Saeed Mahameed <[email-masked]>
---
 drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c b/drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c
index ca7691930f6b..1daa4b019513 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c
@@ -393,10 +393,12 @@ static int mlx5_ptp_freq_adj_real_time(struct mlx5_core_dev *mdev, long scaled_p
 
 	MLX5_SET(mtutc_reg, in, operation, MLX5_MTUTC_OPERATION_ADJUST_FREQ_UTC);
 
-	if (MLX5_CAP_MCAM_FEATURE(mdev, mtutc_freq_adj_units)) {
+	if (MLX5_CAP_MCAM_FEATURE(mdev, mtutc_freq_adj_units) &&
+	    scaled_ppm <= S32_MAX && scaled_ppm >= S32_MIN) {
+		/* HW scaled_ppm support on mlx5 devices only supports a 32-bit value */
 		MLX5_SET(mtutc_reg, in, freq_adj_units,
 			 MLX5_MTUTC_FREQ_ADJ_UNITS_SCALED_PPM);
-		MLX5_SET(mtutc_reg, in, freq_adjustment, scaled_ppm);
+		MLX5_SET(mtutc_reg, in, freq_adjustment, (s32)scaled_ppm);
 	} else {
 		MLX5_SET(mtutc_reg, in, freq_adj_units, MLX5_MTUTC_FREQ_ADJ_UNITS_PPB);
 		MLX5_SET(mtutc_reg, in, freq_adjustment, scaled_ppm_to_ppb(scaled_ppm));
-- 
2.41.0