[PATCH net-next v2 2/2] net: pcs: xpcs: Add handling for 4 channel rsfec device

[mike.marciniszyn@gmail.com]

From: "Mike Marciniszyn (Meta)" <mike.marciniszyn@gmail.com>

This patch introduces the configuration of vendor specific
registers for alignment encoding, PCS Mode, and VL_INTVL
over the one or two instances as required.

The DW_PCS IP specification calls out the need to configure both
lanes identically when using 2 lane modes such as 50-R2 and 100-R2, so
the programming is repeated for each lane.

The encoding tables are derived from the IEEE 8023-2022 spec sections
82.2.7 and tables 82-2 and 82-3 for the alignment markers and their
insertion.

Note that there is a conflict between VRs DW_VR_XS_PCS_DIG_STS and
and the DW_PCS_IP DW_VR_MII_PCS_PCS_MODE.  The bit mask for
DW_VR_XS_PCS_DIG_STS/RX_FIFO_ERR fits within the reserved bits for
the DW_PCS IP the DW_VR_MII_PCS_PCS_MODE register so there is no issue.

There is also a confict between DW_VR_MII_PCS_VL_INTVL and
DW_VR_MII_AN_INTR_STS but an_mode differs, so again there is no issue.

Reviewed-by: Alexander Duyck <alexanderduyck@fb.com>
Signed-off-by: Mike Marciniszyn (Meta) <mike.marciniszyn@gmail.com>
---
v2:
  - Replace xpcs_write_pcs_prtad() wiht xpcs_write_pcs_mdev() to
    avoid hardcoded prtaddr value
v1: https://lore.kernel.org/all/20260506190904.4029-3-mike.marciniszyn@gmail.com/

 drivers/net/pcs/pcs-xpcs.c | 91 +++++++++++++++++++++++++++++++++++++-
 drivers/net/pcs/pcs-xpcs.h | 25 +++++++++++
 2 files changed, 115 insertions(+), 1 deletion(-)

diff --git a/drivers/net/pcs/pcs-xpcs.c b/drivers/net/pcs/pcs-xpcs.c
index 14f89e56958c..42d64f7ebf34 100644
--- a/drivers/net/pcs/pcs-xpcs.c
+++ b/drivers/net/pcs/pcs-xpcs.c
@@ -1423,9 +1423,39 @@ static int xpcs_get_pma_mmd(struct dw_xpcs *xpcs)
 	return -ENODEV;
 }
 
+/* m0 - m2 from Table 82-2/82-3
+ * m4 - m6 are skipped since they are inversions of m0 - m2.
+ * Inverted parity fields (IEEE 82.2.8) bip3 and bip7 are omitted.
+ */
+struct lane_markers {
+	u8 m0, m1, m2;
+};
+
+/* Alignment marker encodings, see table 82-2 in IEEE 802.3-2022 */
+static const struct lane_markers xpcs_100gbaser_markers[] = {
+	{0xc1, 0x68, 0x21},
+	{0x9d, 0x71, 0x8e},
+	{0x59, 0x4b, 0xe8},
+	{0x4d, 0x95, 0x7b},
+};
+
+/* Alignment marker encodings, see table 82-3 in IEEE 802.3-2022
+ * The content of the 50G markers is identical to 40G values (IEEE 133.2.2).
+ */
+static const struct lane_markers xpcs_50gbaser_markers[] = {
+	{0x90, 0x76, 0x47},
+	{0xf0, 0xc4, 0xe6},
+	{0xc5, 0x65, 0x9b},
+	{0xa2, 0x79, 0x3d},
+};
+
 struct pma_pcs_values {
+	const struct lane_markers *vl0_markers;
+	const struct lane_markers *vl123_markers;
 	int lanes;
 	u16 rsfec_ctrl;
+	u16 pcs_mode;
+	u16 vl_intvl;
 };
 
 static struct mdio_device *xpcs_find_first_mdev(struct dw_xpcs *xpcs)
@@ -1448,11 +1478,38 @@ xpcs_find_next_mdev(struct dw_xpcs *xpcs, struct mdio_device *mdev)
 	return &n->mdio;
 }
 
+#define XPCS_VL_TO_REG(vl, lh) \
+	(((vl) * 2) + DW_VR_MII_PCS_VL0_##lh)
+
+static int
+xpcs_write_pcs_mdev(struct mdio_device *mdev, int reg, u16 val)
+{
+	return mdiodev_c45_write(mdev, MDIO_MMD_PCS, reg, val);
+}
+
+static int
+xpcs_config_vl_markers(struct dw_xpcs *xpcs, int vl, struct mdio_device *mdev,
+		       const struct lane_markers *m)
+{
+	int ret;
+
+	/* m0, m1, m2 written to _L and _H registers
+	 *
+	 * _L = (m1 << 8) | m0
+	 * _H = m2
+	 */
+	ret = xpcs_write_pcs_mdev(mdev, XPCS_VL_TO_REG(vl, L),
+				  ((u16)m->m1 << 8) | m->m0);
+	if (ret < 0)
+		return ret;
+	return xpcs_write_pcs_mdev(mdev, XPCS_VL_TO_REG(vl, H), m->m2);
+}
+
 static int
 xpcs_config_rsfec_pma(struct dw_xpcs *xpcs, const struct pma_pcs_values *v)
 {
+	int ret = 0, i, vl, pma_mmd;
 	struct mdio_device *mdev;
-	int ret = 0, i, pma_mmd;
 
 	pma_mmd = xpcs_get_pma_mmd(xpcs);
 	if (pma_mmd < 1)
@@ -1464,6 +1521,23 @@ xpcs_config_rsfec_pma(struct dw_xpcs *xpcs, const struct pma_pcs_values *v)
 
 	for (i = 0; mdev && ret >= 0 && i < v->lanes;
 	     i++, mdev = xpcs_find_next_mdev(xpcs, mdev)) {
+		/* code word markings */
+		for (vl = 0; mdev && ret >= 0 && vl < 4; vl++)
+			ret = xpcs_config_vl_markers(xpcs, vl, mdev,
+						     !vl ? &v->vl0_markers[0] :
+						     &v->vl123_markers[vl - 1]);
+		if (ret < 0)
+			break;
+		/* vendor registers */
+		ret = xpcs_write_pcs_mdev(mdev, DW_VR_MII_PCS_VL_INTVL,
+					  v->vl_intvl);
+		if (ret < 0)
+			break;
+		ret = xpcs_write_pcs_mdev(mdev, DW_VR_MII_PCS_PCS_MODE,
+					  v->pcs_mode);
+		if (ret < 0)
+			break;
+		/* rsfec register */
 		ret = mdiodev_c45_write(mdev, pma_mmd, MDIO_PMA_RSFEC_CTRL,
 					v->rsfec_ctrl);
 	}
@@ -1478,6 +1552,13 @@ static int xpcs_25gbaser_pma_config(struct dw_xpcs *xpcs)
 	const struct pma_pcs_values v = {
 		.rsfec_ctrl = 0,
 		.lanes = 1,
+		/* 25g markers from 100g and 50g tables per 802.3-2022
+		 * 108.5.2.4
+		 */
+		.vl0_markers = &xpcs_100gbaser_markers[0],
+		.vl123_markers = &xpcs_50gbaser_markers[1],
+		.vl_intvl = 20479,
+		.pcs_mode = DW_VR_MII_PCS_MODE_CLAUSE107,
 	};
 
 	return xpcs_config_rsfec_pma(xpcs, &v);
@@ -1488,6 +1569,10 @@ static int xpcs_50gbaser_pma_config(struct dw_xpcs *xpcs)
 	const struct pma_pcs_values v = {
 		.rsfec_ctrl = DW_VR_RSFEC_CTRL_TC_PAD_ALTER,
 		.lanes = 2,
+		.vl0_markers = &xpcs_50gbaser_markers[0],
+		.vl123_markers = &xpcs_50gbaser_markers[1],
+		.pcs_mode = 0,
+		.vl_intvl = 20479,
 	};
 
 	return xpcs_config_rsfec_pma(xpcs, &v);
@@ -1498,6 +1583,10 @@ static int xpcs_100gbasep_pma_config(struct dw_xpcs *xpcs)
 	const struct pma_pcs_values v = {
 		.rsfec_ctrl = MDIO_PMA_RSFEC_CTRL_4LANE_PMD,
 		.lanes = 2,
+		.vl0_markers = &xpcs_100gbaser_markers[0],
+		.vl123_markers = &xpcs_100gbaser_markers[1],
+		.pcs_mode = DW_VR_MII_PCS_MODE_DISABLE_MLD,
+		.vl_intvl = 16383,
 	};
 
 	return xpcs_config_rsfec_pma(xpcs, &v);
diff --git a/drivers/net/pcs/pcs-xpcs.h b/drivers/net/pcs/pcs-xpcs.h
index 187cdec30e70..8161d75370e6 100644
--- a/drivers/net/pcs/pcs-xpcs.h
+++ b/drivers/net/pcs/pcs-xpcs.h
@@ -100,6 +100,31 @@
  */
 #define DW_VR_RSFEC_CTRL_TC_PAD_ALTER	BIT(10)
 
+/* Vendor specific 4 channel PCS registers */
+
+/* DW_VR_MII_PCS_VL_INTVL and DW_VR_MII_AN_INTR_STS conflict
+ * but code paths are different
+ */
+#define DW_VR_MII_PCS_VL_INTVL		0x8002
+/* 0x8008 - 0x800f */
+#define DW_VR_MII_PCS_VL0_L		0x8008
+#define DW_VR_MII_PCS_VL0_H		0x8009
+#define DW_VR_MII_PCS_PCS_MODE		0x8010
+
+/* DW_VR_MII_PCS_PCS_MODE bits */
+#define DW_VR_MII_PCS_MODE_HI_BER25		BIT(2)
+#define DW_VR_MII_PCS_MODE_DISABLE_MLD		BIT(1)
+#define DW_VR_MII_PCS_MODE_CLAUSE49		BIT(0)
+
+/* 25G requires these two bits are set.
+ *
+ * The CLAUSE49 bit changes the interface with the MAC
+ * to 64 bit and the BER25 bit changes the measurement
+ * interval to 2ms.
+ */
+#define DW_VR_MII_PCS_MODE_CLAUSE107 \
+	(DW_VR_MII_PCS_MODE_HI_BER25 | DW_VR_MII_PCS_MODE_CLAUSE49)
+
 #define DW_XPCS_INFO_DECLARE(_name, _pcs, _pma)				\
 	static const struct dw_xpcs_info _name = { .pcs = _pcs, .pma = _pma }
 
-- 
2.43.0