begin adding phy package

phy/mdio.go

@@ -0,0 +1,14 @@
+package phy
+
+// MDIOBus is a HAL for MDIO bus access supporting both Clause 22 and Clause 45 devices.
+// Implementations should use devaddr to select the framing:
+//   - devaddr=0: Clause 22 framing (devaddr ignored in transaction)
+//   - devaddr>=1: Clause 45 framing (PMA/PMD=1, WIS=2, PCS=3, PHY XS=4, DTE XS=5, AN=7)
+//
+// Register address range: Clause 22 uses 0-31, Clause 45 uses 0-65535.
+type MDIOBus interface {
+	// Read reads a 16-bit register from the PHY.
+	Read(phyAddr, devaddr uint8, regAddr uint16) (value uint16, err error)
+	// Write writes a 16-bit value to a PHY register.
+	Write(phyAddr, devaddr uint8, regAddr, value uint16) error
+}

phy/phy.go

@@ -0,0 +1,93 @@
+// Package phy provides Ethernet PHY management via MDIO.
+// It supports IEEE 802.3 Clause 22 and Clause 45 register access
+// for configuring and monitoring physical layer transceivers.
+package phy
+
+import (
+	"errors"
+	"time"
+)
+
+// FindPHYs finds all regular non-clause45 PHYs on the MDIO bus and writes them to dst.
+func FindPHYs(mdio MDIOBus, dst []uint8) (n int, err error) {
+	const maxAddr = 31
+	const regBasicStatus = 0x01
+	if len(dst) < 32 {
+		return -1, errors.New("require buffer length 32 for FindPHYs")
+	}
+	n = 0
+	for addr := uint8(0); addr <= maxAddr; addr++ {
+		// Future proofing for supported clause 45.
+		// Check PMA/PMD device (DEVAD 1), register 0 (control)
+		const devAddr = 1
+		var val uint16
+		val, err = mdio.Read(addr, devAddr, BMCRAddr)
+		if err != nil {
+			continue
+		}
+		// Basic status has some bits that must be zero and one, so if this check fails then we know its a bad address.
+		if val != 0xffff && val != 0x0000 {
+			dst[n] = addr
+			n++
+		}
+		time.Sleep(150 * time.Microsecond)
+	}
+	return n, err
+}
+
+type Device struct {
+	mdio    MDIOBus
+	phyaddr uint8
+	// Is 1 for Clause 45 devices and 0 for clause 22 devices.
+	clause45 uint8
+}
+
+func (d *Device) BasicControl() (BMCR, error) {
+	ctl, err := d.rread(BMCRAddr)
+	return BMCR(ctl), err
+}
+
+func (d *Device) BasicStatus(phyaddr uint8) (BMSR, error) {
+	stat, err := d.rread(BMSRAddr)
+	return BMSR(stat), err
+}
+
+func (d *Device) ID1() (uint16, error) {
+	return d.rread(regPhyId1)
+}
+
+func (d *Device) ID2() (uint16, error) {
+	return d.rread(regPhyId2)
+}
+
+func (d *Device) Reset(phyaddr uint8) error {
+	err := d.rwrite(BMCRAddr, uint16(BMCRReset))
+	if err != nil {
+		return err
+	}
+	// Wait for reset to complete (bit self-clears).
+	// IEEE 802.3 allows up to 500ms.
+	const maxPolls = 50
+	const resetTimeout = 500 * time.Millisecond // As per standard.
+	for i := 0; i < maxPolls; i++ {
+		time.Sleep(resetTimeout / maxPolls)
+		ctl, err := d.BasicControl()
+		if err != nil {
+			continue
+		}
+		if ctl&BMCRReset == 0 {
+			return nil
+		}
+	}
+	return errors.New("PHY reset timeout")
+}
+
+// rwrite mdio register write.
+func (d *Device) rwrite(addr uint16, value uint16) error {
+	return d.mdio.Write(d.phyaddr, d.clause45, addr, value)
+}
+
+// rread mdio register read.
+func (d *Device) rread(addr uint16) (value uint16, _ error) {
+	return d.mdio.Read(d.phyaddr, d.clause45, addr)
+}

phy/reg.go

@@ -0,0 +1,63 @@
+package phy
+
+// Registers 0..15 as defined by 802.3.
+const (
+	// First two registers are BMCR and BMSR. See below.
+
+	regPhyId1 = 0x02
+	regPhyId2 = 0x03
+
+	regAutoNegotiationAdvertisement      = 0x04
+	regAutoNegotiationLinkPartnerAbility = 0x05
+	regAutoNegotiationExpansion          = 0x05
+	regModeControlStatus                 = 0x11
+	regSpecialModes                      = 0x12
+	regSymbolErorCounter                 = 0x1a
+	regSpecialControlStatusIndications   = 0x1b
+	regIRQSourceFlag                     = 0x1d
+	regIRQMask                           = 0x1e
+	regPhySpecialScontrolStatus          = 0x1f
+)
+
+// BMCR represents the Basic Mode Control Register at address 0x00.
+// Reference: IEEE 802.3 Clause 22.2.4.1
+type BMCR uint16
+
+const (
+	BMCRAddr = 0x00
+
+	BMCRSpeed1000  BMCR = 0x0040 // MSB of Speed (1000Mbps)
+	BMCRCollision  BMCR = 0x0080 // Collision test
+	BMCRFullDuplex BMCR = 0x0100 // Full duplex mode
+	BMCRANRestart  BMCR = 0x0200 // Restart auto-negotiation
+	BMCRIsolate    BMCR = 0x0400 // Isolate PHY from MII
+	BMCRPowerDown  BMCR = 0x0800 // Power down PHY
+	BMCRANEnable   BMCR = 0x1000 // Enable auto-negotiation
+	BMCRSpeed100   BMCR = 0x2000 // Select 100Mbps
+	BMCRLoopback   BMCR = 0x4000 // Enable TXD loopback
+	BMCRReset      BMCR = 0x8000 // Software reset (self-clearing)
+)
+
+// BMSR represents the Basic Mode Status Register at address 0x01.
+// Reference: IEEE 802.3 Clause 22.2.4.2
+type BMSR uint16
+
+const (
+	BMSRAddr = 0x01
+
+	BMSRExtCap      BMSR = 0x0001 // Extended register capability
+	BMSRJabber      BMSR = 0x0002 // Jabber detected
+	BMSRLinkStatus  BMSR = 0x0004 // Link status (1=up)
+	BMSRANCap       BMSR = 0x0008 // Auto-negotiation capable
+	BMSRRemoteFault BMSR = 0x0010 // Remote fault detected
+	BMSRANComplete  BMSR = 0x0020 // Auto-negotiation complete
+	BMSRNoPreamble  BMSR = 0x0040 // Preamble suppression capable
+	BMSRExtStatus   BMSR = 0x0100 // Extended status in register 15
+	BMSR100Half2    BMSR = 0x0200 // 100BASE-T2 half-duplex capable
+	BMSR100Full2    BMSR = 0x0400 // 100BASE-T2 full-duplex capable
+	BMSR10Half      BMSR = 0x0800 // 10Mbps half-duplex capable
+	BMSR10Full      BMSR = 0x1000 // 10Mbps full-duplex capable
+	BMSR100Half     BMSR = 0x2000 // 100Mbps half-duplex capable
+	BMSR100Full     BMSR = 0x4000 // 100Mbps full-duplex capable
+	BMSR100Base4    BMSR = 0x8000 // 100BASE-T4 capable
+)