spi: more refactoring

samples/mcp3008.go

@@ -37,8 +37,6 @@ func main() {
 		if err != nil {
 			panic(err)
 		}
-
 		fmt.Printf("analog value is: %v\n", val)
 	}
-
 }

samples/spi.go

@@ -18,9 +18,9 @@ func main() {
 	spiBus := embd.NewSPIBus(embd.SPIMode0, 0, 1000000, 8, 0)
 	defer spiBus.Close()
 
-	dataBuf := []uint8{1, 2, 3}
+	dataBuf := [3]uint8{1, 2, 3}
 
-	if err := spiBus.TransferAndRecieveData(dataBuf); err != nil {
+	if err := spiBus.TransferAndRecieveData(dataBuf[:]); err != nil {
 		panic(err)
 	}
 

samples/spimcp3008.go

@@ -36,12 +36,10 @@ func main() {
 }
 
 func getSensorValue(bus embd.SPIBus) (uint16, error) {
-	data := make([]uint8, 3)
+	data := [3]uint8{1, 128, 0}
-	data[0] = 1
+
-	data[1] = 128
-	data[2] = 0
 	var err error
-	err = bus.TransferAndRecieveData(data)
+	err = bus.TransferAndRecieveData(data[:])
 	if err != nil {
 		return uint16(0), err
 	}

spi.go

@@ -40,8 +40,10 @@ type SPIBus interface {
 // SPIDriver interface interacts with the host descriptors to allow us
 // control of SPI communication.
 type SPIDriver interface {
+	// Bus returns a SPIBus interface which allows us to use spi functionalities
 	Bus(byte, byte, int, int, int) SPIBus
 
+	// Close cleans up all the initialized SPIbus
 	Close() error
 }
 

spidriver.go

@@ -14,6 +14,8 @@ type spiDriver struct {
 	sbf spiBusFactory
 }
 
+// NewSPIDriver returns a SPIDriver interface which allows control
+// over the SPI bus.
 func NewSPIDriver(spiDevMinor byte, sbf spiBusFactory, i func() error) SPIDriver {
 	return &spiDriver{
 		spiDevMinor: spiDevMinor,
@@ -22,6 +24,7 @@ func NewSPIDriver(spiDevMinor byte, sbf spiBusFactory, i func() error) SPIDriver
 	}
 }
 
+// Bus returns a SPIBus interface which allows us to use spi functionalities
 func (s *spiDriver) Bus(mode, channel byte, speed, bpw, delay int) SPIBus {
 	s.busMapLock.Lock()
 	defer s.busMapLock.Unlock()
@@ -32,6 +35,7 @@ func (s *spiDriver) Bus(mode, channel byte, speed, bpw, delay int) SPIBus {
 	return b
 }
 
+// Close cleans up all the initialized SPIbus
 func (s *spiDriver) Close() error {
 	for _, b := range s.busMap {
 		b.Close()