1 files changed, 161 insertions, 0 deletions
diff --git a/sw/usbcom/usb/usb.go b/sw/usbcom/usb/usb.go
new file mode 100644
index 0000000..1fecf4a
--- /dev/null
+++ b/sw/usbcom/usb/usb.go
@@ -0,0 +1,161 @@
+package usb
+
+import (
+	"fmt"
+
+	"github.com/google/gousb"
+)
+
+const (
+	vendorId  gousb.ID = 0x04d8
+	productId gousb.ID = 0x000a
+
+	inEndpointAddr  = 0x82
+	outEndpointAddr = 0x02
+)
+
+type Device struct {
+	ctx       *gousb.Context
+	dev       *gousb.Device
+	closeIntf func()
+	in        *gousb.ReadStream  // IN endpoint (device->host)
+	out       *gousb.WriteStream // OUT endpoint (host->device)
+}
+
+func Connect() (*Device, error) {
+	ctx := gousb.NewContext()
+
+	dev, err := ctx.OpenDeviceWithVIDPID(vendorId, productId)
+	if err != nil {
+		ctx.Close()
+		return nil, err
+	}
+
+	intf, closeIntf, err := interfaceByClass(dev, gousb.ClassData)
+	if err != nil {
+		dev.Close()
+		ctx.Close()
+		return nil, err
+	}
+
+	inEp, err := intf.InEndpoint(inEndpointAddr)
+	if err != nil {
+		closeIntf()
+		dev.Close()
+		ctx.Close()
+		return nil, err
+	}
+
+	inEpDesc, ok := intf.Setting.Endpoints[inEndpointAddr]
+	if !ok {
+		closeIntf()
+		dev.Close()
+		ctx.Close()
+		return nil, fmt.Errorf("no such endpoint: %x", inEndpointAddr)
+	}
+
+	in, err := inEp.NewStream(inEpDesc.MaxPacketSize, 1)
+	if err != nil {
+		closeIntf()
+		dev.Close()
+		ctx.Close()
+		return nil, err
+	}
+
+	outEp, err := intf.OutEndpoint(outEndpointAddr)
+	if err != nil {
+		closeIntf()
+		dev.Close()
+		ctx.Close()
+		return nil, err
+	}
+
+	outEpDesc, ok := intf.Setting.Endpoints[outEndpointAddr]
+	if !ok {
+		closeIntf()
+		dev.Close()
+		ctx.Close()
+		return nil, fmt.Errorf("no such endpoint: %x", outEndpointAddr)
+	}
+
+	out, err := outEp.NewStream(outEpDesc.MaxPacketSize, 1)
+	if err != nil {
+		closeIntf()
+		dev.Close()
+		ctx.Close()
+		return nil, err
+	}
+
+	return &Device{
+		ctx,
+		dev,
+		closeIntf,
+		in, out,
+	}, nil
+}
+
+func interfaceByClass(dev *gousb.Device, class gousb.Class) (intf *gousb.Interface, close func(), err error) {
+	cfgNum, err := dev.ActiveConfigNum()
+	if err != nil {
+		return nil, nil, fmt.Errorf("failed to get active config number of device %s: %v", dev, err)
+	}
+	cfg, err := dev.Config(cfgNum)
+	if err != nil {
+		return nil, nil, fmt.Errorf("failed to claim config %d of device %s: %v", cfgNum, dev, err)
+	}
+
+	intfNum, altNum, ok := func() (int, int, bool) {
+		for i, intf := range cfg.Desc.Interfaces {
+			for a, alt := range intf.AltSettings {
+				if alt.Class == class {
+					return i, a, true
+				}
+			}
+		}
+		return -1, -1, false
+	}()
+	if !ok {
+		cfg.Close()
+		return nil, nil, fmt.Errorf("failed to get %s interface of device %s: %v", class, dev, err)
+	}
+
+	intf, err = cfg.Interface(intfNum, altNum)
+	if err != nil {
+		cfg.Close()
+		return nil, nil, fmt.Errorf("failed to select interface (%d,%d) of config %d of device %s: %v", intfNum, altNum, cfgNum, dev, err)
+	}
+
+	return intf, func() {
+		intf.Close()
+		cfg.Close()
+	}, nil
+}
+
+func (dev *Device) Close() error {
+	outErr := dev.out.Close()
+	inErr := dev.in.Close()
+	dev.closeIntf()
+	devErr := dev.dev.Close()
+	ctxErr := dev.ctx.Close()
+
+	return nonNil(outErr, inErr, devErr, ctxErr)
+}
+
+func nonNil(errs ...error) error {
+	for _, err := range errs {
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// Read from the IN endpoint (device->host)
+func (dev *Device) Read(p []byte) (n int, err error) {
+	return dev.in.Read(p)
+}
+
+// Write to the OUT endpoint (host->device)
+func (dev *Device) Write(p []byte) (n int, err error) {
+	return dev.out.Write(p)
+}