[PATCH RFC net-next 2/4] net: xpcs: add SGMII mode setting

["Russell King (Oracle)" <rmk+kernel@armlinux.org.uk>]

Add SGMII mode setting which configures whether XPCS immitates the MAC
end of the link or the PHY end, and in the latter case, where the data
for generating the link's configuration word comes from. This ties up
all the register bits necessary to configure this mode into one
control.

Set this to PHY_HW mode for TXGBE.

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
---
 drivers/net/pcs/pcs-xpcs.c | 19 +++++++++++--------
 drivers/net/pcs/pcs-xpcs.h | 14 ++++++++++++++
 2 files changed, 25 insertions(+), 8 deletions(-)

diff --git a/drivers/net/pcs/pcs-xpcs.c b/drivers/net/pcs/pcs-xpcs.c
index 12a3d5a80b45..9d54c04ef6ee 100644
--- a/drivers/net/pcs/pcs-xpcs.c
+++ b/drivers/net/pcs/pcs-xpcs.c
@@ -706,12 +706,10 @@ static int xpcs_config_aneg_c37_sgmii(struct dw_xpcs *xpcs,
 		break;
 	}
 
-	if (xpcs->info.pma == WX_TXGBE_XPCS_PMA_10G_ID) {
-		/* Hardware requires it to be PHY side SGMII */
-		tx_conf = DW_VR_MII_TX_CONFIG_PHY_SIDE_SGMII;
-	} else {
+	if (xpcs->sgmii_mode == DW_XPCS_SGMII_MODE_MAC)
 		tx_conf = DW_VR_MII_TX_CONFIG_MAC_SIDE_SGMII;
-	}
+	else
+		tx_conf = DW_VR_MII_TX_CONFIG_PHY_SIDE_SGMII;
 
 	val |= FIELD_PREP(DW_VR_MII_TX_CONFIG_MASK, tx_conf);
 
@@ -722,12 +720,16 @@ static int xpcs_config_aneg_c37_sgmii(struct dw_xpcs *xpcs,
 	val = 0;
 	mask = DW_VR_MII_DIG_CTRL1_2G5_EN | DW_VR_MII_DIG_CTRL1_MAC_AUTO_SW;
 
-	if (neg_mode == PHYLINK_PCS_NEG_INBAND_ENABLED)
-		val = DW_VR_MII_DIG_CTRL1_MAC_AUTO_SW;
+	switch (xpcs->sgmii_mode) {
+	case DW_XPCS_SGMII_MODE_MAC:
+		if (neg_mode == PHYLINK_PCS_NEG_INBAND_ENABLED)
+			val = DW_VR_MII_DIG_CTRL1_MAC_AUTO_SW;
+		break;
 
-	if (xpcs->info.pma == WX_TXGBE_XPCS_PMA_10G_ID) {
+	case DW_XPCS_SGMII_MODE_PHY_HW:
 		mask |= DW_VR_MII_DIG_CTRL1_PHY_MODE_CTRL;
 		val |= DW_VR_MII_DIG_CTRL1_PHY_MODE_CTRL;
+		break;
 	}
 
 	ret = xpcs_modify(xpcs, MDIO_MMD_VEND2, DW_VR_MII_DIG_CTRL1, mask, val);
@@ -1462,6 +1464,7 @@ static struct dw_xpcs *xpcs_create(struct mdio_device *mdiodev)
 	if (xpcs->info.pma == WX_TXGBE_XPCS_PMA_10G_ID) {
 		xpcs->pcs.poll = false;
 		xpcs->sgmii_10_100_8bit = DW_XPCS_SGMII_10_100_8BIT;
+		xpcs->sgmii_mode = DW_XPCS_SGMII_MODE_PHY_HW;
 	} else {
 		xpcs->need_reset = true;
 	}
diff --git a/drivers/net/pcs/pcs-xpcs.h b/drivers/net/pcs/pcs-xpcs.h
index 4d53ccf917f3..892b85425787 100644
--- a/drivers/net/pcs/pcs-xpcs.h
+++ b/drivers/net/pcs/pcs-xpcs.h
@@ -120,6 +120,19 @@ enum dw_xpcs_sgmii_10_100 {
 	DW_XPCS_SGMII_10_100_8BIT
 };
 
+/* The SGMII mode:
+ * DW_XPCS_SGMII_MODE_MAC: the XPCS acts as a MAC, reading and acknowledging
+ * the config word.
+ *
+ * DW_XPCS_SGMII_MODE_PHY_HW: the XPCS acts as a PHY, deriving the tx_config
+ * bits 15 (link), 12 (duplex) and 11:10 (speed) from hardware inputs to the
+ * XPCS.
+ */
+enum dw_xpcs_sgmii_mode {
+	DW_XPCS_SGMII_MODE_MAC,		/* XPCS is MAC on SGMII */
+	DW_XPCS_SGMII_MODE_PHY_HW,	/* XPCS is PHY, tx_config from hw */
+};
+
 struct dw_xpcs {
 	struct dw_xpcs_info info;
 	const struct dw_xpcs_desc *desc;
@@ -130,6 +143,7 @@ struct dw_xpcs {
 	bool need_reset;
 	/* Width of the MII MAC/XPCS interface in 100M and 10M modes */
 	enum dw_xpcs_sgmii_10_100 sgmii_10_100_8bit;
+	enum dw_xpcs_sgmii_mode sgmii_mode;
 };
 
 int xpcs_read(struct dw_xpcs *xpcs, int dev, u32 reg);
-- 
2.30.2