package generic import ( "fmt" "os" "sync" "syscall" "unsafe" "github.com/golang/glog" "github.com/kidoman/embd" ) const ( spiIOCWrMode = 0x40016B01 spiIOCWrBitsPerWord = 0x40016B03 spiIOCWrMaxSpeedHz = 0x40046B04 spiIOCRdMode = 0x80016B01 spiIOCRdBitsPerWord = 0x80016B03 spiIOCRdMaxSpeedHz = 0x80046B04 spiIOCMessage0 = 1073769216 //0x40006B00 spiIOCIncrementor = 2097152 //0x200000 defaultDelayms = 0 defaultSPIBPW = 8 defaultSPISpeed = 1000000 ) type spiIOCTransfer struct { txBuf uint64 rxBuf uint64 length uint32 speedHz uint32 delayus uint16 bitsPerWord uint8 csChange uint8 pad uint32 } type spiBus struct { file *os.File spiDevMinor int channel byte mode byte speed int bpw int delayms int mu sync.Mutex spiTransferData spiIOCTransfer initialized bool initializer func() error } func spiIOCMessageN(n uint32) uint32 { return (spiIOCMessage0 + (n * spiIOCIncrementor)) } func NewSPIBus(spiDevMinor int, mode, channel byte, speed, bpw, delay int, i func() error) embd.SPIBus { return &spiBus{ spiDevMinor: spiDevMinor, mode: mode, channel: channel, speed: speed, bpw: bpw, delayms: delay, initializer: i, } } func (b *spiBus) init() error { if b.initialized { return nil } if b.initializer != nil { if err := b.initializer(); err != nil { return err } } var err error if b.file, err = os.OpenFile(fmt.Sprintf("/dev/spidev%v.%v", b.spiDevMinor, b.channel), os.O_RDWR, os.ModeExclusive); err != nil { return err } glog.V(3).Infof("spi: sucessfully opened file /dev/spidev%v.%v", b.spiDevMinor, b.channel) if err = b.setMode(); err != nil { return err } b.spiTransferData = spiIOCTransfer{} if err = b.setSpeed(); err != nil { return err } if err = b.setBPW(); err != nil { return err } b.setDelay() glog.V(2).Infof("spi: bus %v initialized", b.channel) glog.V(3).Infof("spi: bus %v initialized with spiIOCTransfer as %v", b.channel, b.spiTransferData) b.initialized = true return nil } func (b *spiBus) setMode() error { var mode = uint8(b.mode) glog.V(3).Infof("spi: setting spi mode to %v", mode) _, _, errno := syscall.Syscall(syscall.SYS_IOCTL, b.file.Fd(), spiIOCWrMode, uintptr(unsafe.Pointer(&mode))) if errno != 0 { err := syscall.Errno(errno) glog.V(3).Infof("spi: failed to set mode due to %v", err.Error()) return err } glog.V(3).Infof("spi: mode set to %v", mode) return nil } func (b *spiBus) setSpeed() error { var speed uint32 = defaultSPISpeed if b.speed > 0 { speed = uint32(b.speed) } glog.V(3).Infof("spi: setting spi speedMax to %v", speed) _, _, errno := syscall.Syscall(syscall.SYS_IOCTL, b.file.Fd(), spiIOCWrMaxSpeedHz, uintptr(unsafe.Pointer(&speed))) if errno != 0 { err := syscall.Errno(errno) glog.V(3).Infof("spi: failed to set speedMax due to %v", err.Error()) return err } glog.V(3).Infof("spi: speedMax set to %v", speed) b.spiTransferData.speedHz = speed return nil } func (b *spiBus) setBPW() error { var bpw uint8 = defaultSPIBPW if b.bpw > 0 { bpw = uint8(b.bpw) } glog.V(3).Infof("spi: setting spi bpw to %v", bpw) _, _, errno := syscall.Syscall(syscall.SYS_IOCTL, b.file.Fd(), spiIOCWrBitsPerWord, uintptr(unsafe.Pointer(&bpw))) if errno != 0 { err := syscall.Errno(errno) glog.V(3).Infof("spi: failed to set bpw due to %v", err.Error()) return err } glog.V(3).Infof("spi: bpw set to %v", bpw) b.spiTransferData.bitsPerWord = uint8(bpw) return nil } func (b *spiBus) setDelay() { var delay uint16 = defaultDelayms if b.delayms > 0 { delay = uint16(b.delayms) } glog.V(3).Infof("spi: delayms set to %v", delay) b.spiTransferData.delayus = delay } func (b *spiBus) TransferAndReceiveData(dataBuffer []uint8) error { if err := b.init(); err != nil { return err } len := len(dataBuffer) dataCarrier := b.spiTransferData dataCarrier.length = uint32(len) dataCarrier.txBuf = uint64(uintptr(unsafe.Pointer(&dataBuffer[0]))) dataCarrier.rxBuf = uint64(uintptr(unsafe.Pointer(&dataBuffer[0]))) glog.V(3).Infof("spi: sending dataBuffer %v with carrier %v", dataBuffer, dataCarrier) _, _, errno := syscall.Syscall(syscall.SYS_IOCTL, b.file.Fd(), uintptr(spiIOCMessageN(1)), uintptr(unsafe.Pointer(&dataCarrier))) if errno != 0 { err := syscall.Errno(errno) glog.V(3).Infof("spi: failed to read due to %v", err.Error()) return err } glog.V(3).Infof("spi: read into dataBuffer %v", dataBuffer) return nil } func (b *spiBus) ReceiveData(len int) ([]uint8, error) { if err := b.init(); err != nil { return nil, err } data := make([]uint8, len) if err := b.TransferAndReceiveData(data); err != nil { return nil, err } return data, nil } func (b *spiBus) TransferAndReceiveByte(data byte) (byte, error) { if err := b.init(); err != nil { return 0, err } d := [1]uint8{uint8(data)} if err := b.TransferAndReceiveData(d[:]); err != nil { return 0, err } return d[0], nil } func (b *spiBus) ReceiveByte() (byte, error) { if err := b.init(); err != nil { return 0, err } var d [1]uint8 if err := b.TransferAndReceiveData(d[:]); err != nil { return 0, err } return byte(d[0]), nil } func (b *spiBus) Write(data []byte) (n int, err error) { if err := b.init(); err != nil { return 0, err } return b.file.Write(data) } func (b *spiBus) Close() error { b.mu.Lock() defer b.mu.Unlock() if !b.initialized { return nil } return b.file.Close() }