net: phy: broadcom: add 1000Base-X support for BCM54616S

The BCM54616S PHY cannot work properly in RGMII->1000Base-X mode, mainly
because genphy functions are designed for copper links, and 1000Base-X
(clause 37) auto negotiation needs to be handled differently.

This patch enables 1000Base-X support for BCM54616S by customizing 3
driver callbacks, and it's verified to be working on Facebook CMM BMC
platform (RGMII->1000Base-KX):

  - probe: probe callback detects PHY's operation mode based on
    INTERF_SEL[1:0] pins and 1000X/100FX selection bit in SerDES 100-FX
    Control register.

  - config_aneg: calls genphy_c37_config_aneg when the PHY is running in
    1000Base-X mode; otherwise, genphy_config_aneg will be called.

  - read_status: calls genphy_c37_read_status when the PHY is running in
    1000Base-X mode; otherwise, genphy_read_status will be called.

Note: BCM54616S PHY can also be configured in RGMII->100Base-FX mode, and
100Base-FX support is not available as of now.

Signed-off-by: Tao Ren <taoren@fb.com>
Acked-by: Vladimir Oltean <olteanv@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/broadcom.c

@@ -359,9 +359,9 @@ static int bcm5482_config_init(struct phy_device *phydev)
 		/*
 		 * Select 1000BASE-X register set (primary SerDes)
 		 */
-		reg = bcm_phy_read_shadow(phydev, BCM5482_SHD_MODE);
-		bcm_phy_write_shadow(phydev, BCM5482_SHD_MODE,
-				     reg | BCM5482_SHD_MODE_1000BX);
+		reg = bcm_phy_read_shadow(phydev, BCM54XX_SHD_MODE);
+		bcm_phy_write_shadow(phydev, BCM54XX_SHD_MODE,
+				     reg | BCM54XX_SHD_MODE_1000BX);
 
 		/*
 		 * LED1=ACTIVITYLED, LED3=LINKSPD[2]
@@ -427,12 +427,47 @@ static int bcm5481_config_aneg(struct phy_device *phydev)
 	return ret;
 }
 
+static int bcm54616s_probe(struct phy_device *phydev)
+{
+	int val, intf_sel;
+
+	val = bcm_phy_read_shadow(phydev, BCM54XX_SHD_MODE);
+	if (val < 0)
+		return val;
+
+	/* The PHY is strapped in RGMII-fiber mode when INTERF_SEL[1:0]
+	 * is 01b, and the link between PHY and its link partner can be
+	 * either 1000Base-X or 100Base-FX.
+	 * RGMII-1000Base-X is properly supported, but RGMII-100Base-FX
+	 * support is still missing as of now.
+	 */
+	intf_sel = (val & BCM54XX_SHD_INTF_SEL_MASK) >> 1;
+	if (intf_sel == 1) {
+		val = bcm_phy_read_shadow(phydev, BCM54616S_SHD_100FX_CTRL);
+		if (val < 0)
+			return val;
+
+		/* Bit 0 of the SerDes 100-FX Control register, when set
+		 * to 1, sets the MII/RGMII -> 100BASE-FX configuration.
+		 * When this bit is set to 0, it sets the GMII/RGMII ->
+		 * 1000BASE-X configuration.
+		 */
+		if (!(val & BCM54616S_100FX_MODE))
+			phydev->dev_flags |= PHY_BCM_FLAGS_MODE_1000BX;
+	}
+
+	return 0;
+}
+
 static int bcm54616s_config_aneg(struct phy_device *phydev)
 {
 	int ret;
 
 	/* Aneg firsly. */
-	ret = genphy_config_aneg(phydev);
+	if (phydev->dev_flags & PHY_BCM_FLAGS_MODE_1000BX)
+		ret = genphy_c37_config_aneg(phydev);
+	else
+		ret = genphy_config_aneg(phydev);
 
 	/* Then we can set up the delay. */
 	bcm54xx_config_clock_delay(phydev);
@@ -440,6 +475,18 @@ static int bcm54616s_config_aneg(struct phy_device *phydev)
 	return ret;
 }
 
+static int bcm54616s_read_status(struct phy_device *phydev)
+{
+	int err;
+
+	if (phydev->dev_flags & PHY_BCM_FLAGS_MODE_1000BX)
+		err = genphy_c37_read_status(phydev);
+	else
+		err = genphy_read_status(phydev);
+
+	return err;
+}
+
 static int brcm_phy_setbits(struct phy_device *phydev, int reg, int set)
 {
 	int val;
@@ -631,6 +678,8 @@ static struct phy_driver broadcom_drivers[] = {
 	.config_aneg	= bcm54616s_config_aneg,
 	.ack_interrupt	= bcm_phy_ack_intr,
 	.config_intr	= bcm_phy_config_intr,
+	.read_status	= bcm54616s_read_status,
+	.probe		= bcm54616s_probe,
 }, {
 	.phy_id		= PHY_ID_BCM5464,
 	.phy_id_mask	= 0xfffffff0,

include/linux/brcmphy.h

@@ -200,9 +200,15 @@
 #define BCM5482_SHD_SSD		0x14	/* 10100: Secondary SerDes control */
 #define BCM5482_SHD_SSD_LEDM	0x0008	/* SSD LED Mode enable */
 #define BCM5482_SHD_SSD_EN	0x0001	/* SSD enable */
-#define BCM5482_SHD_MODE	0x1f	/* 11111: Mode Control Register */
-#define BCM5482_SHD_MODE_1000BX	0x0001	/* Enable 1000BASE-X registers */
 
+/* 10011: SerDes 100-FX Control Register */
+#define BCM54616S_SHD_100FX_CTRL	0x13
+#define	BCM54616S_100FX_MODE		BIT(0)	/* 100-FX SerDes Enable */
+
+/* 11111: Mode Control Register */
+#define BCM54XX_SHD_MODE		0x1f
+#define BCM54XX_SHD_INTF_SEL_MASK	GENMASK(2, 1)	/* INTERF_SEL[1:0] */
+#define BCM54XX_SHD_MODE_1000BX		BIT(0)	/* Enable 1000-X registers */
 
 /*
  * EXPANSION SHADOW ACCESS REGISTERS.  (PHY REG 0x15, 0x16, and 0x17)