usb: add USB mass storage class support

Author: mikesmitty

GNUmakefile

@@ -792,6 +792,10 @@ endif
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=feather-nrf52840    examples/usb-midi
 	@$(MD5SUM) test.hex
+	$(TINYGO) build -size short -o test.hex -target=pico    			examples/usb-storage
+	@$(MD5SUM) test.hex
+	$(TINYGO) build -size short -o test.hex -target=pico2    			examples/usb-storage
+	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=nrf52840-s140v6-uf2-generic	examples/machinetest
 	@$(MD5SUM) test.hex
 ifneq ($(STM32), 0)

src/examples/usb-storage/main.go

@@ -0,0 +1,15 @@
+package main
+
+import (
+	"machine"
+	"machine/usb/msc"
+	"time"
+)
+
+func main() {
+	msc.Port(machine.Flash)
+
+	for {
+		time.Sleep(2 * time.Second)
+	}
+}

src/machine/usb/descriptor/endpoint.go

@@ -4,6 +4,17 @@ import (
 	"internal/binary"
 )
 
+/* Endpoint Descriptor
+USB 2.0 Specification: 9.6.6 Endpoint
+*/
+
+const (
+	TransferTypeControl uint8 = iota
+	TransferTypeIsochronous
+	TransferTypeBulk
+	TransferTypeInterrupt
+)
+
 var endpointEP1IN = [endpointTypeLen]byte{
 	endpointTypeLen,
 	TypeEndpoint,
@@ -74,6 +85,36 @@ var EndpointEP5OUT = EndpointType{
 	data: endpointEP5OUT[:],
 }
 
+// Mass Storage Class bulk in endpoint
+var endpointMSCIN = [endpointTypeLen]byte{
+	endpointTypeLen,
+	TypeEndpoint,
+	0x86,             // EndpointAddress
+	TransferTypeBulk, // Attributes
+	0x40,             // MaxPacketSizeL (64 bytes)
+	0x00,             // MaxPacketSizeH
+	0x00,             // Interval
+}
+
+var EndpointMSCIN = EndpointType{
+	data: endpointMSCIN[:],
+}
+
+// Mass Storage Class bulk out endpoint
+var endpointMSCOUT = [endpointTypeLen]byte{
+	endpointTypeLen,
+	TypeEndpoint,
+	0x07,             // EndpointAddress
+	TransferTypeBulk, // Attributes
+	0x40,             // MaxPacketSizeL (64 bytes)
+	0x00,             // MaxPacketSizeH
+	0x00,             // Interval
+}
+
+var EndpointMSCOUT = EndpointType{
+	data: endpointMSCOUT[:],
+}
+
 const (
 	endpointTypeLen = 7
 )
@@ -109,3 +150,7 @@ func (d EndpointType) MaxPacketSize(v uint16) {
 func (d EndpointType) Interval(v uint8) {
 	d.data[6] = byte(v)
 }
+
+func (d EndpointType) GetMaxPacketSize() uint16 {
+	return binary.LittleEndian.Uint16(d.data[4:6])
+}

src/machine/usb/descriptor/msc.go

@@ -0,0 +1,75 @@
+package descriptor
+
+const (
+	interfaceClassMSC = 0x08
+	mscSubclassSCSI   = 0x06
+	mscProtocolBOT    = 0x50
+)
+
+var interfaceAssociationMSC = [interfaceAssociationTypeLen]byte{
+	interfaceAssociationTypeLen,
+	TypeInterfaceAssociation,
+	0x02,              // FirstInterface
+	0x01,              // InterfaceCount
+	interfaceClassMSC, // FunctionClass
+	mscSubclassSCSI,   // FunctionSubClass
+	mscProtocolBOT,    // FunctionProtocol
+	0x00,              // Function
+}
+
+var InterfaceAssociationMSC = InterfaceAssociationType{
+	data: interfaceAssociationMSC[:],
+}
+
+var interfaceMSC = [interfaceTypeLen]byte{
+	interfaceTypeLen,  // Length
+	TypeInterface,     // DescriptorType
+	0x02,              // InterfaceNumber
+	0x00,              // AlternateSetting
+	0x02,              // NumEndpoints
+	interfaceClassMSC, // InterfaceClass (Mass Storage)
+	mscSubclassSCSI,   // InterfaceSubClass (SCSI Transparent)
+	mscProtocolBOT,    // InterfaceProtocol (Bulk-Only Transport)
+	0x00,              // Interface
+}
+
+var InterfaceMSC = InterfaceType{
+	data: interfaceMSC[:],
+}
+
+var configurationMSC = [configurationTypeLen]byte{
+	configurationTypeLen,
+	TypeConfiguration,
+	0x6a, 0x00, // wTotalLength
+	0x03, // number of interfaces (bNumInterfaces)
+	0x01, // configuration value (bConfigurationValue)
+	0x00, // index to string description (iConfiguration)
+	0xa0, // attributes (bmAttributes)
+	0x32, // maxpower (100 mA) (bMaxPower)
+}
+
+var ConfigurationMSC = ConfigurationType{
+	data: configurationMSC[:],
+}
+
+// Mass Storage Class
+var MSC = Descriptor{
+	Device: DeviceCDC.Bytes(),
+	Configuration: Append([][]byte{
+		ConfigurationMSC.Bytes(),
+		InterfaceAssociationCDC.Bytes(),
+		InterfaceCDCControl.Bytes(),
+		ClassSpecificCDCHeader.Bytes(),
+		ClassSpecificCDCACM.Bytes(),
+		ClassSpecificCDCUnion.Bytes(),
+		ClassSpecificCDCCallManagement.Bytes(),
+		EndpointEP1IN.Bytes(),
+		InterfaceCDCData.Bytes(),
+		EndpointEP2OUT.Bytes(),
+		EndpointEP3IN.Bytes(),
+		InterfaceAssociationMSC.Bytes(),
+		InterfaceMSC.Bytes(),
+		EndpointMSCIN.Bytes(),
+		EndpointMSCOUT.Bytes(),
+	}),
+}

src/machine/usb/msc/cbw.go

@@ -0,0 +1,62 @@
+package msc
+
+import (
+	"encoding/binary"
+	"machine/usb/msc/csw"
+	"machine/usb/msc/scsi"
+)
+
+const (
+	cbwMsgLen = 31         // Command Block Wrapper (CBW) message length
+	Signature = 0x43425355 // "USBC" in little endian
+)
+
+type CBW struct {
+	HasCmd bool
+	Data   []byte
+}
+
+func (c *CBW) Tag() uint32 {
+	return binary.LittleEndian.Uint32(c.Data[4:8])
+}
+
+func (c *CBW) length() int {
+	return len(c.Data)
+}
+
+func (c *CBW) validLength() bool {
+	return len(c.Data) == cbwMsgLen
+}
+
+func (c *CBW) validSignature() bool {
+	return binary.LittleEndian.Uint32(c.Data[:4]) == Signature
+}
+
+func (c *CBW) SCSICmd() scsi.Cmd {
+	return scsi.Cmd{Data: c.Data[15:]}
+}
+
+func (c *CBW) transferLength() uint32 {
+	return binary.LittleEndian.Uint32(c.Data[8:12])
+}
+
+// isIn returns true if the command direction is from the device to the host.
+func (c *CBW) isIn() bool {
+	return c.Data[12]>>7 != 0
+}
+
+// isOut returns true if the command direction is from the host to the device.
+func (c *CBW) isOut() bool {
+	return !c.isIn()
+}
+
+func (c *CBW) CSW(status csw.Status, residue uint32, b []byte) {
+	// Signature: "USBS" 53425355h (little endian)
+	binary.LittleEndian.PutUint32(b[:4], csw.Signature)
+	// Tag: (same as CBW)
+	copy(b[4:8], c.Data[4:8])
+	// Data Residue: (untransferred bytes)
+	binary.LittleEndian.PutUint32(b[8:12], residue)
+	// Status:
+	b[12] = byte(status)
+}

src/machine/usb/msc/csw/csw.go

@@ -0,0 +1,14 @@
+package csw
+
+type Status uint8
+
+const (
+	StatusPassed Status = iota
+	StatusFailed
+	StatusPhaseError
+)
+
+const (
+	MsgLen    = 13
+	Signature = 0x53425355 // "USBS" in little endian
+)