net/mlx5e: Add logic to read RS-FEC histogram bin ranges from PPHCR

Introduce support for querying the Ports Phy Histogram Configuration
Register (PPHCR) to retrieve RS-FEC histogram bin ranges. The ranges
are stored in a static array and will be used to map histogram counters
to error levels.

The actual RS-FEC histogram statistics are not yet reported in this
commit and will be handled in a downstream patch.

Co-developed-by: Yael Chemla <ychemla@nvidia.com>
Signed-off-by: Yael Chemla <ychemla@nvidia.com>
Signed-off-by: Carolina Jubran <cjubran@nvidia.com>
Reviewed-by: Dragos Tatulea <dtatulea@nvidia.com>
Reviewed-by: Yael Chemla <ychemla@nvidia.com>
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Link: https://patch.msgid.link/20250924124037.1508846-4-vadim.fedorenko@linux.dev
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

5 files changed, 94 insertions, 3 deletions

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en.h b/drivers/net/ethernet/mellanox/mlx5/core/en.h
index 4ffbc263d60f..14e3207b14e7 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en.h
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en.h
@@ -956,6 +956,7 @@ struct mlx5e_priv {
 	struct mlx5e_mqprio_rl    *mqprio_rl;
 	struct dentry             *dfs_root;
 	struct mlx5_devcom_comp_dev *devcom;
+	struct ethtool_fec_hist_range *fec_ranges;
 };
 
 struct mlx5e_dev {
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c b/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c
index bcc3bbb78cc9..fd45384a855b 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c
@@ -1932,7 +1932,7 @@ static void mlx5e_get_fec_stats(struct net_device *netdev,
 {
 	struct mlx5e_priv *priv = netdev_priv(netdev);
 
-	mlx5e_stats_fec_get(priv, fec_stats);
+	mlx5e_stats_fec_get(priv, fec_stats, hist);
 }
 
 static int mlx5e_get_fecparam(struct net_device *netdev,
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
index 5e007bb3bad1..0c79c42ae538 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
@@ -6279,8 +6279,15 @@ int mlx5e_priv_init(struct mlx5e_priv *priv,
 	if (!priv->channel_stats)
 		goto err_free_tx_rates;
 
+	priv->fec_ranges = kcalloc(ETHTOOL_FEC_HIST_MAX,
+				   sizeof(*priv->fec_ranges), GFP_KERNEL);
+	if (!priv->fec_ranges)
+		goto err_free_channel_stats;
+
 	return 0;
 
+err_free_channel_stats:
+	kfree(priv->channel_stats);
 err_free_tx_rates:
 	kfree(priv->tx_rates);
 err_free_txq2sq_stats:
@@ -6304,6 +6311,7 @@ void mlx5e_priv_cleanup(struct mlx5e_priv *priv)
 	if (!priv->mdev)
 		return;
 
+	kfree(priv->fec_ranges);
 	for (i = 0; i < priv->stats_nch; i++)
 		kvfree(priv->channel_stats[i]);
 	kfree(priv->channel_stats);
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_stats.c b/drivers/net/ethernet/mellanox/mlx5/core/en_stats.c
index 9c45c6e670eb..f1887b9afa3d 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_stats.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_stats.c
@@ -1491,8 +1491,88 @@ static void fec_set_corrected_bits_total(struct mlx5e_priv *priv,
 				      phy_corrected_bits);
 }
 
+#define MLX5_RS_HISTOGRAM_ENTRIES \
+	(MLX5_FLD_SZ_BYTES(rs_histogram_cntrs, hist) / \
+	 MLX5_FLD_SZ_BYTES(rs_histogram_cntrs, hist[0]))
+
+enum {
+	MLX5E_HISTOGRAM_FEC_RS_544_514 = 1,
+	MLX5E_HISTOGRAM_FEC_LLRS = 2,
+	MLX5E_HISTOGRAM_FEC_RS_528_514 = 3,
+};
+
+static bool fec_rs_validate_hist_type(int mode, int hist_type)
+{
+	switch (mode) {
+	case MLX5E_FEC_RS_528_514:
+		return hist_type == MLX5E_HISTOGRAM_FEC_RS_528_514;
+	case MLX5E_FEC_RS_544_514_INTERLEAVED_QUAD:
+	case MLX5E_FEC_RS_544_514:
+		return hist_type == MLX5E_HISTOGRAM_FEC_RS_544_514;
+	case MLX5E_FEC_LLRS_272_257_1:
+		return hist_type == MLX5E_HISTOGRAM_FEC_LLRS;
+	default:
+		break;
+	}
+
+	return false;
+}
+
+static u8
+fec_rs_histogram_fill_ranges(struct mlx5e_priv *priv, int mode,
+			     const struct ethtool_fec_hist_range **ranges)
+{
+	struct mlx5_core_dev *mdev = priv->mdev;
+	u32 out[MLX5_ST_SZ_DW(pphcr_reg)] = {0};
+	u32 in[MLX5_ST_SZ_DW(pphcr_reg)] = {0};
+	int sz = MLX5_ST_SZ_BYTES(pphcr_reg);
+	u8 hist_type, num_of_bins;
+
+	memset(priv->fec_ranges, 0,
+	       ETHTOOL_FEC_HIST_MAX * sizeof(*priv->fec_ranges));
+	MLX5_SET(pphcr_reg, in, local_port, 1);
+	if (mlx5_core_access_reg(mdev, in, sz, out, sz, MLX5_REG_PPHCR, 0, 0))
+		return 0;
+
+	hist_type = MLX5_GET(pphcr_reg, out, active_hist_type);
+	if (!fec_rs_validate_hist_type(mode, hist_type))
+		return 0;
+
+	num_of_bins = MLX5_GET(pphcr_reg, out, num_of_bins);
+	if (WARN_ON_ONCE(num_of_bins > MLX5_RS_HISTOGRAM_ENTRIES))
+		return 0;
+
+	for (int i = 0; i < num_of_bins; i++) {
+		void *bin_range = MLX5_ADDR_OF(pphcr_reg, out, bin_range[i]);
+
+		priv->fec_ranges[i].high = MLX5_GET(bin_range_layout, bin_range,
+						    high_val);
+		priv->fec_ranges[i].low = MLX5_GET(bin_range_layout, bin_range,
+						   low_val);
+	}
+	*ranges = priv->fec_ranges;
+
+	return num_of_bins;
+}
+
+static void fec_set_histograms_stats(struct mlx5e_priv *priv, int mode,
+				     struct ethtool_fec_hist *hist)
+{
+	switch (mode) {
+	case MLX5E_FEC_RS_528_514:
+	case MLX5E_FEC_RS_544_514:
+	case MLX5E_FEC_LLRS_272_257_1:
+	case MLX5E_FEC_RS_544_514_INTERLEAVED_QUAD:
+		fec_rs_histogram_fill_ranges(priv, mode, &hist->ranges);
+		break;
+	default:
+		return;
+	}
+}
+
 void mlx5e_stats_fec_get(struct mlx5e_priv *priv,
-			 struct ethtool_fec_stats *fec_stats)
+			 struct ethtool_fec_stats *fec_stats,
+			 struct ethtool_fec_hist *hist)
 {
 	int mode = fec_active_mode(priv->mdev);
 
@@ -1502,6 +1582,7 @@ void mlx5e_stats_fec_get(struct mlx5e_priv *priv,
 
 	fec_set_corrected_bits_total(priv, fec_stats);
 	fec_set_block_stats(priv, mode, fec_stats);
+	fec_set_histograms_stats(priv, mode, hist);
 }
 
 #define PPORT_ETH_EXT_OFF(c) \
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_stats.h b/drivers/net/ethernet/mellanox/mlx5/core/en_stats.h
index 72dbcc1928ef..09f155acb461 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_stats.h
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_stats.h
@@ -117,7 +117,8 @@ void mlx5e_stats_update_ndo_stats(struct mlx5e_priv *priv);
 void mlx5e_stats_pause_get(struct mlx5e_priv *priv,
 			   struct ethtool_pause_stats *pause_stats);
 void mlx5e_stats_fec_get(struct mlx5e_priv *priv,
-			 struct ethtool_fec_stats *fec_stats);
+			 struct ethtool_fec_stats *fec_stats,
+			 struct ethtool_fec_hist *hist);
 
 void mlx5e_stats_eth_phy_get(struct mlx5e_priv *priv,
 			     struct ethtool_eth_phy_stats *phy_stats);