hci: refactor to separate HCI transport implementation from interface to not always assume UART.

Signed-off-by: deadprogram <ron@hybridgroup.com>

adapter_hci.go

@@ -3,17 +3,16 @@
 package bluetooth
 
 import (
-	"machine"
 	"runtime"
 
 	"time"
 )
 
-// hciAdapter represents the implementation for the UART connection to the HCI controller.
+// hciAdapter represents the implementation for the connection to the HCI controller.
 type hciAdapter struct {
-	uart *machine.UART
-	hci  *hci
-	att  *att
+	hciport hciTransport
+	hci     *hci
+	att     *att
 
 	isDefault bool
 	scanning  bool
@@ -49,8 +48,8 @@ func (a *hciAdapter) Address() (MACAddress, error) {
 	return MACAddress{MAC: makeAddress(a.hci.address)}, nil
 }
 
-func newBLEStack(uart *machine.UART) (*hci, *att) {
-	h := newHCI(uart)
+func newBLEStack(port hciTransport) (*hci, *att) {
+	h := newHCI(port)
 	a := newATT(h)
 	h.att = a
 

adapter_hci_uart.go

@@ -8,10 +8,12 @@ import (
 
 const maxConnections = 1
 
-// Adapter represents the UART connection to the HCI controller.
+// Adapter represents a "plain" UART connection to the HCI controller.
 type Adapter struct {
 	hciAdapter
 
+	uart *machine.UART
+
 	// used for software flow control
 	cts, rts machine.Pin
 }
@@ -20,11 +22,13 @@ type Adapter struct {
 //
 // Make sure to call Enable() before using it to initialize the adapter.
 var DefaultAdapter = &Adapter{
-	isDefault: true,
-	connectHandler: func(device Device, connected bool) {
-		return
+	hciAdapter: hciAdapter{
+		isDefault: true,
+		connectHandler: func(device Device, connected bool) {
+			return
+		},
+		connectedDevices: make([]Device, 0, maxConnections),
 	},
-	connectedDevices: make([]Device, 0, maxConnections),
 }
 
 // SetUART sets the UART to use for the HCI connection.
@@ -49,16 +53,66 @@ func (a *Adapter) SetSoftwareFlowControl(cts, rts machine.Pin) error {
 // Enable configures the BLE stack. It must be called before any
 // Bluetooth-related calls (unless otherwise indicated).
 func (a *Adapter) Enable() error {
-	a.hci, a.att = newBLEStack(a.uart)
-
+	transport := &hciUART{uart: a.uart}
 	if a.cts != 0 && a.rts != 0 {
-		a.hci.softRTS = a.rts
-		a.hci.softRTS.Configure(machine.PinConfig{Mode: machine.PinOutput})
-		a.hci.softRTS.High()
+		transport.rts = a.rts
+		a.rts.Configure(machine.PinConfig{Mode: machine.PinOutput})
+		a.rts.High()
 
-		a.hci.softCTS = a.cts
+		transport.cts = a.cts
 		a.cts.Configure(machine.PinConfig{Mode: machine.PinInput})
 	}
 
+	a.hci, a.att = newBLEStack(transport)
 	a.enable()
+
+	return nil
+}
+
+type hciUART struct {
+	uart *machine.UART
+
+	// used for software flow control
+	cts, rts machine.Pin
+}
+
+func (h *hciUART) startRead() {
+	if h.rts != machine.NoPin {
+		h.rts.Low()
+	}
+}
+
+func (h *hciUART) endRead() {
+	if h.rts != machine.NoPin {
+		h.rts.High()
+	}
+}
+
+func (h *hciUART) Buffered() int {
+	return h.uart.Buffered()
+}
+
+func (h *hciUART) ReadByte() (byte, error) {
+	return h.uart.ReadByte()
+}
+
+const writeAttempts = 200
+
+func (h *hciUART) Write(buf []byte) (int, error) {
+	if h.cts != machine.NoPin {
+		retries := writeAttempts
+		for h.cts.Get() {
+			retries--
+			if retries == 0 {
+				return 0, ErrHCITimeout
+			}
+		}
+	}
+
+	n, err := h.uart.Write(buf)
+	if err != nil {
+		return 0, err
+	}
+
+	return n, nil
 }

adapter_ninafw.go

@@ -9,7 +9,7 @@ import (
 
 const maxConnections = 1
 
-// Adapter represents the HCI connection to the NINA fw.
+// Adapter represents the HCI connection to the NINA fw using the hardware UART.
 type Adapter struct {
 	hciAdapter
 }
@@ -54,16 +54,15 @@ func (a *Adapter) Enable() error {
 
 	uart.Configure(cfg)
 
-	a.hci, a.att = newBLEStack(uart)
+	transport := &hciUART{uart: uart}
 	if machine.NINA_SOFT_FLOWCONTROL {
-		a.hci.softRTS = machine.NINA_RTS
-		a.hci.softRTS.Configure(machine.PinConfig{Mode: machine.PinOutput})
-		a.hci.softRTS.High()
+		machine.NINA_RTS.Configure(machine.PinConfig{Mode: machine.PinOutput})
+		machine.NINA_RTS.High()
 
-		a.hci.softCTS = machine.NINA_CTS
 		machine.NINA_CTS.Configure(machine.PinConfig{Mode: machine.PinInput})
 	}
 
+	a.hci, a.att = newBLEStack(transport)
 	return a.enable()
 }
 
@@ -84,3 +83,48 @@ func resetNINAInverted() {
 	machine.NINA_RESETN.High()
 	time.Sleep(1000 * time.Millisecond)
 }
+
+type hciUART struct {
+	uart *machine.UART
+}
+
+func (h *hciUART) startRead() {
+	if machine.NINA_SOFT_FLOWCONTROL {
+		machine.NINA_RTS.Low()
+	}
+}
+
+func (h *hciUART) endRead() {
+	if machine.NINA_SOFT_FLOWCONTROL {
+		machine.NINA_RTS.High()
+	}
+}
+
+func (h *hciUART) Buffered() int {
+	return h.uart.Buffered()
+}
+
+func (h *hciUART) ReadByte() (byte, error) {
+	return h.uart.ReadByte()
+}
+
+const writeAttempts = 200
+
+func (h *hciUART) Write(buf []byte) (int, error) {
+	if machine.NINA_SOFT_FLOWCONTROL {
+		retries := writeAttempts
+		for machine.NINA_CTS.Get() {
+			retries--
+			if retries == 0 {
+				return 0, ErrHCITimeout
+			}
+		}
+	}
+
+	n, err := h.uart.Write(buf)
+	if err != nil {
+		return 0, err
+	}
+
+	return n, nil
+}

hci.go

@@ -1,4 +1,4 @@
-//go:build ninafw
+//go:build ninafw || hci
 
 package bluetooth
 
@@ -6,7 +6,6 @@ import (
 	"encoding/binary"
 	"encoding/hex"
 	"errors"
-	"machine"
 	"time"
 )
 
@@ -122,10 +121,16 @@ type leConnectData struct {
 	timeout        uint16
 }
 
+type hciTransport interface {
+	startRead()
+	endRead()
+	Buffered() int
+	ReadByte() (byte, error)
+	Write(buf []byte) (int, error)
+}
+
 type hci struct {
-	uart              *machine.UART
-	softCTS           machine.Pin
-	softRTS           machine.Pin
+	transport         hciTransport
 	att               *att
 	l2cap             *l2cap
 	buf               []byte
@@ -140,24 +145,19 @@ type hci struct {
 	pendingPkt        uint16
 }
 
-func newHCI(uart *machine.UART) *hci {
+func newHCI(t hciTransport) *hci {
 	return &hci{
-		uart:    uart,
-		softCTS: machine.NoPin,
-		softRTS: machine.NoPin,
-		buf:     make([]byte, 256),
+		transport: t,
+		buf:       make([]byte, 256),
 	}
 }
 
 func (h *hci) start() error {
-	if h.softRTS != machine.NoPin {
-		h.softRTS.Low()
+	h.transport.startRead()
+	defer h.transport.endRead()
 
-		defer h.softRTS.High()
-	}
-
-	for h.uart.Buffered() > 0 {
-		h.uart.ReadByte()
+	for h.transport.Buffered() > 0 {
+		h.transport.ReadByte()
 	}
 
 	return nil
@@ -172,15 +172,12 @@ func (h *hci) reset() error {
 }
 
 func (h *hci) poll() error {
-	if h.softRTS != machine.NoPin {
-		h.softRTS.Low()
-
-		defer h.softRTS.High()
-	}
+	h.transport.startRead()
+	defer h.transport.endRead()
 
 	i := 0
-	for h.uart.Buffered() > 0 {
-		data, _ := h.uart.ReadByte()
+	for h.transport.Buffered() > 0 {
+		data, _ := h.transport.ReadByte()
 		h.buf[i] = data
 
 		done, err := h.processPacket(i)
@@ -487,25 +484,8 @@ func (h *hci) sendAclPkt(handle uint16, cid uint8, data []byte) error {
 	return nil
 }
 
-const writeAttempts = 200
-
 func (h *hci) write(buf []byte) (int, error) {
-	if h.softCTS != machine.NoPin {
-		retries := writeAttempts
-		for h.softCTS.Get() {
-			retries--
-			if retries == 0 {
-				return 0, ErrHCITimeout
-			}
-		}
-	}
-
-	n, err := h.uart.Write(buf)
-	if err != nil {
-		return 0, err
-	}
-
-	return n, nil
+	return h.transport.Write(buf)
 }
 
 type aclDataHeader struct {

l2cap_hci.go

@@ -1,4 +1,4 @@
-//go:build ninafw
+//go:build ninafw || hci
 
 package bluetooth