[PATCH net-next 2/2] net: macb: add support for reporting SGMII inband link status

[Charles Perry <charles.perry@microchip.com>]

This makes it possible to use in-band autonegotiation with
SGMII.

If using a device tree, this can be done by adding the managed =
"in-band-status" property to the gem node.

Signed-off-by: Charles Perry <charles.perry@microchip.com>
---

Notes:
    Logs with inband aneg:
    
    root@p64h:~# ifconfig eth1 up 10.180.59.33
    macb 40004184000.ethernet eth1: PHY 4000c21e000.mdio-mdio:02 doesn't supply possible interfaces
    macb 40004184000.ethernet eth1: PHY [4000c21e000.mdio-mdio:02] driver [Microsemi GE VSC8574 SyncE] (irq=POLL)
    macb 40004184000.ethernet eth1: phy: sgmii setting supported 00000000,00000000,00000000,000042ff advertising 00000000,00000000,00000000,000042ff
    macb 40004184000.ethernet eth1: configuring for inband/sgmii link mode
    macb 40004184000.ethernet eth1: major config, requested inband/sgmii
    macb 40004184000.ethernet eth1: interface sgmii inband modes: pcs=00 phy=03
    pcs_ib_caps=0x0 phy_ib_caps=0x3
    macb 40004184000.ethernet eth1: major config, active inband/inband,an-enabled/sgmii
    macb 40004184000.ethernet eth1: phylink_mac_config: mode=inband/sgmii/none adv=00000000,00000000,00000000,000042ff pause=00
    PCSANADV=0x1 PCSCNTRL=0x1040
    PCSSTS=0x109 PCSANLPBASE=0x1801
    PCSSTS=0x12d PCSANLPBASE=0x1801
    macb 40004184000.ethernet eth1: phy link down sgmii/Unknown/Unknown/none/off/nolpi
    PCSSTS=0x12d PCSANLPBASE=0x1801
    PCSSTS=0x12d PCSANLPBASE=0x1801
    macb 40004184000.ethernet eth1: phy link up sgmii/1Gbps/Full/none/tx/nolpi
    PCSSTS=0x129 PCSANLPBASE=0x9801
    PCSSTS=0x12d PCSANLPBASE=0x9801
    macb 40004184000.ethernet eth1: Link is Up - 1Gbps/Full - flow control tx
    
    Logs without inband aneg:
    
    macb 40004184000.ethernet eth1: PHY 4000c21e000.mdio-mdio:02 doesn't supply possible interfaces
    macb 40004184000.ethernet eth1: PHY [4000c21e000.mdio-mdio:02] driver [Microsemi GE VSC8574 SyncE] (irq=POLL)
    macb 40004184000.ethernet eth1: phy: sgmii setting supported 00000000,00000000,00000000,000042ff advertising 00000000,00000000,00000000,000042ff
    macb 40004184000.ethernet eth1: configuring for phy/sgmii link mode
    macb 40004184000.ethernet eth1: major config, requested phy/sgmii
    macb 40004184000.ethernet eth1: interface sgmii inband modes: pcs=00 phy=03
    macb 40004184000.ethernet eth1: major config, active phy/outband/sgmii
    macb 40004184000.ethernet eth1: phylink_mac_config: mode=phy/sgmii/none adv=00000000,00000000,00000000,00000000 pause=00
    PCSANADV=0x1 PCSCNTRL=0x40
    macb 40004184000.ethernet eth1: phy link down sgmii/Unknown/Unknown/none/off/nolpi
    macb 40004184000.ethernet eth1: phy link up sgmii/1Gbps/Full/none/tx/nolpi
    macb 40004184000.ethernet eth1: Link is Up - 1Gbps/Full - flow control tx

 drivers/net/ethernet/cadence/macb_main.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index 5002087cda09..a7a2d7fcb18c 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -560,7 +560,12 @@ static int macb_usx_pcs_config(struct phylink_pcs *pcs,
 static void macb_pcs_get_state(struct phylink_pcs *pcs, unsigned int neg_mode,
 			       struct phylink_link_state *state)
 {
-	state->link = 0;
+	struct macb *bp = container_of(pcs, struct macb, phylink_sgmii_pcs);
+	u16 bmsr, lpa;
+
+	bmsr = gem_readl(bp, PCSSTS);
+	lpa = gem_readl(bp, PCSANLPBASE);
+	phylink_mii_c22_pcs_decode_state(state, neg_mode, bmsr, lpa);
 }
 
 static void macb_pcs_an_restart(struct phylink_pcs *pcs)
-- 
2.47.3