improvements to phy package

phy/phy.go

@@ -56,6 +56,10 @@ func FindClause22PHYs(mdio MDIOBus, dst []uint8) (n int, err error) {
 	return n, err
 }
 
+var (
+	errInvalidPhyAddr = errors.New("invalid phy addr")
+)
+
 type Device struct {
 	mdio    MDIOBus
 	phyaddr uint8
@@ -64,13 +68,17 @@ type Device struct {
 }
 
 // ConfigureAs22 resets all state of device to be used as a Clause22 device. Does not do a software reset.
-func (phy *Device) ConfigureAs22(mdio MDIOBus, phyAddr uint8) {
-	if phyAddr > 31 || mdio == nil {
-		panic("invalid argument to phy.Device.Reset")
+func (phy *Device) ConfigureAs22(mdio MDIOBus, phyAddr uint8) error {
+	if phyAddr > 31 {
+		return errInvalidPhyAddr
+
+	} else if mdio == nil {
+		return errors.New("nil mdio bus")
 	}
 	phy.mdio = mdio
 	phy.phyaddr = phyAddr
 	phy.isClause45 = 0
+	return nil
 }
 
 // IsClause45 returns true if the device uses Clause 45 MDIO addressing (extended register access).
@@ -214,6 +222,57 @@ func (phy *Device) IsLinkUp() (bool, error) {
 	return status&BMSRLinkStatus != 0, nil
 }
 
+// WaitForLinkWithDeadline waits for link to establish until the deadline.
+// If auto-negotiation is enabled (BMCR.ANEnable=1), waits for AN to complete first.
+// Returns true if link is up, false if deadline exceeded.
+//
+// Per IEEE 802.3:
+//   - BMSR.LinkStatus is latched-low, so first read clears any previous fault
+//   - BMSR.ANComplete must be set before link parameters are valid (when AN enabled)
+//   - link_fail_inhibit_timer (50-75ms) delays link indication after AN completes
+func (phy *Device) WaitForLinkWithDeadline(deadline time.Time) (bool, error) {
+	const pollInterval = 50 * time.Millisecond
+	// Check current PHY configuration.
+	// Early exit: link impossible if PHY isolated or powered down.
+	ctl, err := phy.BasicControl()
+	if err != nil {
+		return false, err
+	} else if ctl&BMCRIsolate != 0 {
+		return false, errors.New("PHY isolated from MII")
+	} else if ctl&BMCRPowerDown != 0 {
+		return false, errors.New("PHY powered down")
+	}
+
+	// First read clears latched-low bits (LinkStatus, ANComplete).
+	// This ensures we get fresh status on subsequent reads.
+	_, _ = phy.BasicStatus()
+	anEnabled := ctl&BMCRANEnable != 0
+	for time.Now().Before(deadline) {
+		status, err := phy.BasicStatus()
+		if err != nil {
+			return false, err
+		}
+		// If AN enabled, must wait for it to complete first.
+		// No point checking link status until AN is done.
+		if anEnabled && !status.AutoNegotiationComplete() {
+			time.Sleep(pollInterval)
+			continue
+		}
+		// AN complete (or disabled). Check link status.
+		if status.LinkUp() {
+			return true, nil
+		}
+		time.Sleep(pollInterval)
+	}
+
+	// Final check after deadline.
+	status, err := phy.BasicStatus()
+	if err != nil {
+		return false, err
+	}
+	return status.LinkUp(), nil
+}
+
 // NegotiatedLink returns the auto-negotiated link mode using standard MII registers.
 // Returns LinkMode based on ANAR (our advertisement) AND ANLPAR (link partner ability).
 // Priority order per IEEE 802.3 Annex 28B.3.

phy/reg.go

@@ -11,7 +11,7 @@ const (
 
 	regAutoNegotiationAdvertisement      = 0x04
 	regAutoNegotiationLinkPartnerAbility = 0x05
-	regAutoNegotiationExpansion          = 0x05
+	regAutoNegotiationExpansion          = 0x06
 	regModeControlStatus                 = 0x11
 	regSpecialModes                      = 0x12
 	regSymbolErorCounter                 = 0x1a
@@ -115,22 +115,6 @@ const (
 	ANARPauseMask ANAR = ANARPause | ANARPauseAsym
 )
 
-func (l LinkMode) ANAR() (a ANAR) {
-	switch l {
-	case Link10HDX:
-		a = ANAR10Half
-	case Link10FDX:
-		a = ANAR10Full
-	case Link100HDX:
-		a = ANAR100Half
-	case Link100FDX:
-		a = ANAR100Full
-	case Link100T4:
-		a = ANAR100BaseT4
-	}
-	return a
-}
-
 // WithPause returns ANAR with pause bits set according to parameters.
 //
 // Flow control allows a receiver to signal the sender to pause transmission.
@@ -203,21 +187,22 @@ func (a ANAR) Without100M() ANAR {
 // LinkMode returns the highest priority LinkMode from the ANAR speed bits.
 // Priority order per IEEE 802.3 Annex 28B.3.
 // Returns LinkDown if no speed bits are set.
-func (a ANAR) LinkMode() LinkMode {
+func (a ANAR) LinkMode() (l LinkMode) {
 	switch {
 	case a&ANAR100Full != 0:
-		return Link100FDX
+		l = Link100FDX
 	case a&ANAR100BaseT4 != 0:
-		return Link100T4
+		l = Link100T4
 	case a&ANAR100Half != 0:
-		return Link100HDX
+		l = Link100HDX
 	case a&ANAR10Full != 0:
-		return Link10FDX
+		l = Link10FDX
 	case a&ANAR10Half != 0:
-		return Link10HDX
+		l = Link10HDX
 	default:
-		return LinkDown
+		l = LinkDown
 	}
+	return l
 }
 
 // LinkMode represents the negotiated/force-set Ethernet link speed and duplex mode.
@@ -249,30 +234,48 @@ const (
 	Link100GFDX // 100G-F
 )
 
+func (l LinkMode) ANAR() (a ANAR) {
+	a = NewANAR()
+	switch l {
+	case Link10HDX:
+		a |= ANAR10Half
+	case Link10FDX:
+		a |= ANAR10Full
+	case Link100HDX:
+		a |= ANAR100Half
+	case Link100FDX:
+		a |= ANAR100Full
+	case Link100T4:
+		a |= ANAR100BaseT4
+	}
+	return a
+}
+
 // SpeedMbps returns the link speed in megabits per second.
-func (lm LinkMode) SpeedMbps() int {
+func (lm LinkMode) SpeedMbps() (Mbps int) {
 	switch lm {
 	case Link10HDX, Link10FDX:
-		return 10
+		Mbps = 10
 	case Link100HDX, Link100FDX, Link100T4:
-		return 100
+		Mbps = 100
 	case Link1000HDX, Link1000FDX:
-		return 1000
+		Mbps = 1000
 	case Link2500FDX:
-		return 2500
+		Mbps = 2500
 	case Link5GFDX:
-		return 5000
+		Mbps = 5000
 	case Link10GFDX:
-		return 10_000
+		Mbps = 10_000
 	case Link25GFDX:
-		return 25_000
+		Mbps = 25_000
 	case Link40GFDX:
-		return 40_000
+		Mbps = 40_000
 	case Link100GFDX:
-		return 100_000
+		Mbps = 100_000
 	default:
-		return 0
+		Mbps = 0
 	}
+	return Mbps
 }
 
 // IsFullDuplex returns true if the link mode is full duplex.