[PATCH net-next v4 2/2] net: macb: add support for 1000BASE-X autonegotiation to PCS

[Nathan Whitehorn <nwhitehorn@pa.msu.edu>]

The current PCS code unconditionally uses SGMII autonegotiation, though
the hardware supports both SGMII and 1000BASE-X modes. Decouple the
choice of PCS enablement from use of the SGMII mode when running at
gigabit rates and announce to phylink that 1000BASE-X is a supported
operating mode. This enables direct attachment of the PCS to e.g. an
SFP.

The 1000BASE-X code in phylink also sometimes calls the autonegotiation
restart method, so add an implementation of autonegotiation restart.

Signed-off-by: Nathan Whitehorn <nwhitehorn@pa.msu.edu>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
---
 drivers/net/ethernet/cadence/macb_main.c | 30 ++++++++++++++++++------
 1 file changed, 23 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index c15a9c7e69d3..2252e6a55072 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -583,7 +583,12 @@ static void macb_pcs_get_state(struct phylink_pcs *pcs, unsigned int neg_mode,
 
 static void macb_pcs_an_restart(struct phylink_pcs *pcs)
 {
-	/* Not supported */
+	struct macb *bp = container_of(pcs, struct macb, phylink_sgmii_pcs);
+	u32 old, new;
+
+	old = gem_readl(bp, PCSCNTRL);
+	new = old | BMCR_ANRESTART;
+	gem_writel(bp, PCSCNTRL, new);
 }
 
 static int macb_pcs_config(struct phylink_pcs *pcs,
@@ -609,8 +614,10 @@ static int macb_pcs_config(struct phylink_pcs *pcs,
 		new = old | BMCR_ANENABLE;
 	else
 		new = old & ~BMCR_ANENABLE;
-	if (old != new)
+	if (old != new) {
 		gem_writel(bp, PCSCNTRL, new);
+		return 1;
+	}
 
 	return 0;
 }
@@ -750,7 +757,9 @@ static void macb_mac_config(struct phylink_config *config, unsigned int mode,
 		ctrl &= ~(GEM_BIT(SGMIIEN) | GEM_BIT(PCSSEL));
 		ncr &= ~GEM_BIT(ENABLE_HS_MAC);
 
-		if (state->interface == PHY_INTERFACE_MODE_SGMII) {
+		if (state->interface == PHY_INTERFACE_MODE_1000BASEX) {
+			ctrl |= GEM_BIT(PCSSEL);
+		} else if (state->interface == PHY_INTERFACE_MODE_SGMII) {
 			ctrl |= GEM_BIT(SGMIIEN) | GEM_BIT(PCSSEL);
 		} else if (state->interface == PHY_INTERFACE_MODE_10GBASER) {
 			ctrl |= GEM_BIT(PCSSEL);
@@ -957,7 +966,8 @@ static struct phylink_pcs *macb_mac_select_pcs(struct phylink_config *config,
 
 	if (interface == PHY_INTERFACE_MODE_10GBASER)
 		return &bp->phylink_usx_pcs;
-	else if (interface == PHY_INTERFACE_MODE_SGMII)
+	else if (interface == PHY_INTERFACE_MODE_1000BASEX ||
+	         interface == PHY_INTERFACE_MODE_SGMII)
 		return &bp->phylink_sgmii_pcs;
 	else
 		return NULL;
@@ -1032,7 +1042,8 @@ static int macb_mii_probe(struct net_device *dev)
 	bp->phylink_config.type = PHYLINK_NETDEV;
 	bp->phylink_config.mac_managed_pm = true;
 
-	if (bp->phy_interface == PHY_INTERFACE_MODE_SGMII) {
+	if (bp->phy_interface == PHY_INTERFACE_MODE_1000BASEX ||
+	    bp->phy_interface == PHY_INTERFACE_MODE_SGMII) {
 		bp->phylink_config.poll_fixed_state = true;
 		bp->phylink_config.get_fixed_state = macb_get_pcs_fixed_state;
 		/* The PCSAUTONEG bit in PCSCNTRL is on out of reset. Setting
@@ -1061,9 +1072,12 @@ static int macb_mii_probe(struct net_device *dev)
 			  bp->phylink_config.supported_interfaces);
 		phy_interface_set_rgmii(bp->phylink_config.supported_interfaces);
 
-		if (bp->caps & MACB_CAPS_PCS)
+		if (bp->caps & MACB_CAPS_PCS) {
+			__set_bit(PHY_INTERFACE_MODE_1000BASEX,
+				  bp->phylink_config.supported_interfaces);
 			__set_bit(PHY_INTERFACE_MODE_SGMII,
 				  bp->phylink_config.supported_interfaces);
+		}
 
 		if (bp->caps & MACB_CAPS_HIGH_SPEED) {
 			__set_bit(PHY_INTERFACE_MODE_10GBASER,
@@ -4932,7 +4946,9 @@ static int macb_init_dflt(struct platform_device *pdev)
 	/* Set MII management clock divider */
 	val = macb_mdc_clk_div(bp);
 	val |= macb_dbw(bp);
-	if (bp->phy_interface == PHY_INTERFACE_MODE_SGMII)
+	if (bp->phy_interface == PHY_INTERFACE_MODE_1000BASEX)
+		val |= GEM_BIT(PCSSEL);
+	else if (bp->phy_interface == PHY_INTERFACE_MODE_SGMII)
 		val |= GEM_BIT(SGMIIEN) | GEM_BIT(PCSSEL);
 	macb_writel(bp, NCFGR, val);
 
-- 
2.34.1