gpio: analog pin support for the bbb

bbb.go

@@ -1,10 +1,19 @@
 package embd
 
+import (
+	"errors"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"strconv"
+	"strings"
+)
+
 func init() {
 	Describers[HostBBB] = func(rev int) *Descriptor {
 		return &Descriptor{
 			GPIO: func() GPIO {
-				return newGPIODriver(bbbPins)
+				return newGPIODriver(bbbPins, newDigitalPin, newBBBAnalogPin)
 			},
 			I2C: newI2CDriver,
 		}
@@ -69,12 +78,111 @@ var bbbPins = PinMap{
 	&PinDesc{ID: "P9_30", Aliases: []string{"112", "GPIO_112", "SPI1_D1"}, Caps: CapNormal | CapSPI, DigitalLogical: 112},
 	&PinDesc{ID: "P9_31", Aliases: []string{"110", "GPIO_110", "SPI1_SCLK"}, Caps: CapNormal | CapSPI, DigitalLogical: 110},
 	&PinDesc{ID: "P9_32", Aliases: []string{"VADC"}},
-	&PinDesc{ID: "P9_33", Aliases: []string{"AIN4"}, Caps: CapAnalog, AnalogLogical: 4},
+	&PinDesc{ID: "P9_33", Aliases: []string{"4", "AIN4"}, Caps: CapAnalog, AnalogLogical: 4},
 	&PinDesc{ID: "P9_34", Aliases: []string{"AGND"}},
-	&PinDesc{ID: "P9_35", Aliases: []string{"AIN6"}, Caps: CapAnalog, AnalogLogical: 6},
-	&PinDesc{ID: "P9_36", Aliases: []string{"AIN5"}, Caps: CapAnalog, AnalogLogical: 5},
-	&PinDesc{ID: "P9_37", Aliases: []string{"AIN2"}, Caps: CapAnalog, AnalogLogical: 2},
-	&PinDesc{ID: "P9_38", Aliases: []string{"AIN3"}, Caps: CapAnalog, AnalogLogical: 3},
-	&PinDesc{ID: "P9_39", Aliases: []string{"AIN0"}, Caps: CapAnalog, AnalogLogical: 0},
-	&PinDesc{ID: "P9_40", Aliases: []string{"AIN1"}, Caps: CapAnalog, AnalogLogical: 1},
+	&PinDesc{ID: "P9_35", Aliases: []string{"6", "AIN6"}, Caps: CapAnalog, AnalogLogical: 6},
+	&PinDesc{ID: "P9_36", Aliases: []string{"5", "AIN5"}, Caps: CapAnalog, AnalogLogical: 5},
+	&PinDesc{ID: "P9_37", Aliases: []string{"2", "AIN2"}, Caps: CapAnalog, AnalogLogical: 2},
+	&PinDesc{ID: "P9_38", Aliases: []string{"3", "AIN3"}, Caps: CapAnalog, AnalogLogical: 3},
+	&PinDesc{ID: "P9_39", Aliases: []string{"0", "AIN0"}, Caps: CapAnalog, AnalogLogical: 0},
+	&PinDesc{ID: "P9_40", Aliases: []string{"1", "AIN1"}, Caps: CapAnalog, AnalogLogical: 1},
+}
+
+type bbbAnalogPin struct {
+	n int
+
+	val *os.File
+
+	initialized bool
+}
+
+func newBBBAnalogPin(n int) AnalogPin {
+	return &bbbAnalogPin{n: n}
+}
+
+func (p *bbbAnalogPin) N() int {
+	return p.n
+}
+
+func (p *bbbAnalogPin) init() error {
+	if p.initialized {
+		return nil
+	}
+
+	var err error
+	if err = p.ensureEnabled(); err != nil {
+		return err
+	}
+	if p.val, err = p.valueFile(); err != nil {
+		return err
+	}
+
+	p.initialized = true
+
+	return nil
+}
+
+func (p *bbbAnalogPin) ensureEnabled() error {
+	file := "/sys/devices/bone_capemgr.8/slots"
+	bytes, err := ioutil.ReadFile(file)
+	if err != nil {
+		return err
+	}
+	str := string(bytes)
+	if strings.Contains(str, "cape-bone-iio") {
+		return nil
+	}
+	// Not initialized yet
+	slots, err := os.OpenFile(file, os.O_WRONLY, os.ModeExclusive)
+	if err != nil {
+		return err
+	}
+	defer slots.Close()
+	_, err = slots.WriteString("cape-bone-iio")
+	return err
+}
+
+func (p *bbbAnalogPin) valueFilePath() string {
+	return fmt.Sprintf("/sys/devices/ocp.2/helper.14/AIN%v", p.n)
+}
+
+func (p *bbbAnalogPin) openFile(path string) (*os.File, error) {
+	return os.OpenFile(path, os.O_RDONLY, os.ModeExclusive)
+}
+
+func (p *bbbAnalogPin) valueFile() (*os.File, error) {
+	return p.openFile(p.valueFilePath())
+}
+
+func (p *bbbAnalogPin) Read() (int, error) {
+	if err := p.init(); err != nil {
+		return 0, err
+	}
+
+	p.val.Seek(0, 0)
+	bytes, err := ioutil.ReadAll(p.val)
+	if err != nil {
+		return 0, err
+	}
+	str := string(bytes)
+	str = strings.TrimSpace(str)
+	return strconv.Atoi(str)
+}
+
+func (p *bbbAnalogPin) Write(_ int) error {
+	return errors.New("gpio: not implemented")
+}
+
+func (p *bbbAnalogPin) Close() error {
+	if !p.initialized {
+		return nil
+	}
+
+	if err := p.val.Close(); err != nil {
+		return err
+	}
+
+	p.initialized = false
+
+	return nil
 }

digitalpin.go

@@ -19,10 +19,14 @@ type digitalPin struct {
 	initialized bool
 }
 
-func newDigitalPin(n int) *digitalPin {
+func newDigitalPin(n int) DigitalPin {
 	return &digitalPin{n: n}
 }
 
+func (p *digitalPin) N() int {
+	return p.n
+}
+
 func (p *digitalPin) init() error {
 	if p.initialized {
 		return nil

gpio.go

@@ -13,6 +13,8 @@ const (
 )
 
 type DigitalPin interface {
+	N() int
+
 	Write(val int) error
 	Read() (int, error)
 
@@ -25,8 +27,18 @@ type DigitalPin interface {
 	Close() error
 }
 
+type AnalogPin interface {
+	N() int
+
+	Write(val int) error
+	Read() (int, error)
+
+	Close() error
+}
+
 type GPIO interface {
 	DigitalPin(key interface{}) (DigitalPin, error)
+	AnalogPin(key interface{}) (AnalogPin, error)
 
 	Close() error
 }
@@ -87,3 +99,25 @@ func ActiveLow(key interface{}, b bool) error {
 
 	return pin.ActiveLow(b)
 }
+
+func NewAnalogPin(key interface{}) (AnalogPin, error) {
+	return gpioInstance.AnalogPin(key)
+}
+
+func AnalogWrite(key interface{}, val int) error {
+	pin, err := NewAnalogPin(key)
+	if err != nil {
+		return err
+	}
+
+	return pin.Write(val)
+}
+
+func AnalogRead(key interface{}) (int, error) {
+	pin, err := NewAnalogPin(key)
+	if err != nil {
+		return 0, err
+	}
+
+	return pin.Read()
+}

gpiodriver.go

@@ -1,9 +1,8 @@
 package embd
 
 import (
+	"errors"
 	"fmt"
-
-	"github.com/golang/glog"
 )
 
 type pin interface {
@@ -12,38 +11,53 @@ type pin interface {
 
 type gpioDriver struct {
 	pinMap PinMap
+
+	dpf func(n int) DigitalPin
+	apf func(n int) AnalogPin
+
 	initializedPins map[string]pin
 }
 
-func newGPIODriver(pinMap PinMap) *gpioDriver {
+func newGPIODriver(pinMap PinMap, dpf func(n int) DigitalPin, apf func(n int) AnalogPin) GPIO {
 	return &gpioDriver{
 		pinMap: pinMap,
+		dpf:    dpf,
+		apf:    apf,
+
 		initializedPins: map[string]pin{},
 	}
 }
 
-func (io *gpioDriver) lookupKey(key interface{}, cap int) (*PinDesc, bool) {
-	return io.pinMap.Lookup(key, cap)
-}
-
-func (io *gpioDriver) digitalPin(key interface{}) (*digitalPin, error) {
-	pd, found := io.lookupKey(key, CapNormal)
-	if !found {
-		return nil, fmt.Errorf("gpio: could not find pin matching %q", key)
-	}
-
-	if pd.Caps != CapNormal {
-		glog.Infof("gpio: pin %q is not a dedicated digital io pin. please refer to the system reference manual for more details", key)
-	}
-
-	dp := newDigitalPin(pd.DigitalLogical)
-	io.initializedPins[pd.ID] = dp
-
-	return dp, nil
-}
-
 func (io *gpioDriver) DigitalPin(key interface{}) (DigitalPin, error) {
-	return io.digitalPin(key)
+	if io.dpf == nil {
+		return nil, errors.New("gpio: digital io not supported on this host")
+	}
+
+	pd, found := io.pinMap.Lookup(key, CapNormal)
+	if !found {
+		return nil, fmt.Errorf("gpio: could not find pin matching %v", key)
+	}
+
+	p := io.dpf(pd.DigitalLogical)
+	io.initializedPins[pd.ID] = p
+
+	return p, nil
+}
+
+func (io *gpioDriver) AnalogPin(key interface{}) (AnalogPin, error) {
+	if io.apf == nil {
+		return nil, errors.New("gpio: analog io not supported on this host")
+	}
+
+	pd, found := io.pinMap.Lookup(key, CapAnalog)
+	if !found {
+		return nil, fmt.Errorf("gpio: could not find pin matching %v", key)
+	}
+
+	p := io.apf(pd.AnalogLogical)
+	io.initializedPins[pd.ID] = p
+
+	return p, nil
 }
 
 func (io *gpioDriver) Close() error {

gpiodriver_test.go

@@ -2,6 +2,46 @@ package embd
 
 import "testing"
 
+type fakeDigitalPin struct {
+	n int
+}
+
+func (p *fakeDigitalPin) N() int {
+	return p.n
+}
+
+func (*fakeDigitalPin) SetDirection(dir Direction) error {
+	return nil
+}
+
+func (*fakeDigitalPin) Read() (int, error) {
+	return 0, nil
+}
+
+func (*fakeDigitalPin) Write(val int) error {
+	return nil
+}
+
+func (*fakeDigitalPin) ActiveLow(b bool) error {
+	return nil
+}
+
+func (*fakeDigitalPin) PullUp() error {
+	return nil
+}
+
+func (*fakeDigitalPin) PullDown() error {
+	return nil
+}
+
+func (*fakeDigitalPin) Close() error {
+	return nil
+}
+
+func newFakeDigitalPin(n int) DigitalPin {
+	return &fakeDigitalPin{n}
+}
+
 func TestGpioDriverDigitalPin(t *testing.T) {
 	var tests = []struct {
 		key interface{}
@@ -12,15 +52,86 @@ func TestGpioDriverDigitalPin(t *testing.T) {
 	var pinMap = PinMap{
 		&PinDesc{ID: "P1_1", Aliases: []string{"1"}, Caps: CapNormal, DigitalLogical: 1},
 	}
-	driver := newGPIODriver(pinMap)
+	driver := newGPIODriver(pinMap, newFakeDigitalPin, nil)
 	for _, test := range tests {
-		pin, err := driver.digitalPin(test.key)
+		pin, err := driver.DigitalPin(test.key)
 		if err != nil {
 			t.Errorf("Looking up %v: unexpected error: %v", test.key, err)
 			continue
 		}
-		if pin.n != test.n {
-			t.Errorf("Looking up %v: got %v, want %v", test.key, pin.n, test.n)
+		if pin.N() != test.n {
+			t.Errorf("Looking up %v: got %v, want %v", test.key, pin.N(), test.n)
 		}
 	}
 }
+
+type fakeAnalogPin struct {
+	n int
+}
+
+func (p *fakeAnalogPin) N() int {
+	return p.n
+}
+
+func (*fakeAnalogPin) Read() (int, error) {
+	return 0, nil
+}
+
+func (*fakeAnalogPin) Write(val int) error {
+	return nil
+}
+
+func (*fakeAnalogPin) Close() error {
+	return nil
+}
+
+func newFakeAnalogPin(n int) AnalogPin {
+	return &fakeAnalogPin{n}
+}
+
+func TestGpioDriverAnalogPin(t *testing.T) {
+	var tests = []struct {
+		key interface{}
+		n   int
+	}{
+		{1, 1},
+	}
+	var pinMap = PinMap{
+		&PinDesc{ID: "P1_1", Aliases: []string{"1"}, Caps: CapAnalog, AnalogLogical: 1},
+	}
+	driver := newGPIODriver(pinMap, nil, newFakeAnalogPin)
+	for _, test := range tests {
+		pin, err := driver.AnalogPin(test.key)
+		if err != nil {
+			t.Errorf("Looking up %v: unexpected error: %v", test.key, err)
+			continue
+		}
+		if pin.N() != test.n {
+			t.Errorf("Looking up %v: got %v, want %v", test.key, pin.N(), test.n)
+		}
+	}
+}
+
+func TestGpioDriverUnavailablePinType(t *testing.T) {
+	var pinMap = PinMap{
+		&PinDesc{ID: "P1_1", Aliases: []string{"1"}, Caps: CapNormal, DigitalLogical: 1},
+		&PinDesc{ID: "P1_2", Aliases: []string{"1"}, Caps: CapAnalog, AnalogLogical: 1},
+	}
+	driver := newGPIODriver(pinMap, nil, nil)
+	_, err := driver.DigitalPin(1)
+	if err == nil {
+		t.Fatal("Looking up digital pin 1: did not get error")
+	}
+	expected := "gpio: digital io not supported on this host"
+	if err.Error() != expected {
+		t.Fatalf("Looking up digital pin 1: got error %q, expected %q", err, expected)
+	}
+	_, err = driver.AnalogPin(1)
+	if err == nil {
+		t.Fatal("Looking up analog pin 1: did not get error")
+	}
+	expected = "gpio: analog io not supported on this host"
+	if err.Error() != expected {
+		t.Fatalf("Looking up analog pin 1: got error %q, expected %q", err, expected)
+	}
+}

rpi.go

@@ -9,7 +9,7 @@ func init() {
 
 		return &Descriptor{
 			GPIO: func() GPIO {
-				return newGPIODriver(pins)
+				return newGPIODriver(pins, newDigitalPin, nil)
 			},
 			I2C: newI2CDriver,
 		}

samples/.gitignore

@@ -1,3 +1,4 @@
+analog
 bh1750fvi
 bmp085
 bmp180

samples/analog.go

@@ -0,0 +1,42 @@
+// +build ignore
+
+package main
+
+import (
+	"fmt"
+	"os"
+	"os/signal"
+	"time"
+
+	"github.com/kidoman/embd"
+)
+
+func main() {
+	if err := embd.InitGPIO(); err != nil {
+		panic(err)
+	}
+	defer embd.CloseGPIO()
+
+	pin, err := embd.NewAnalogPin(0)
+	if err != nil {
+		panic(err)
+	}
+	defer pin.Close()
+
+	quit := make(chan os.Signal, 1)
+	signal.Notify(quit, os.Interrupt, os.Kill)
+	defer signal.Stop(quit)
+
+	for {
+		select {
+		case <-time.After(100 * time.Millisecond):
+			val, err := pin.Read()
+			if err != nil {
+				panic(err)
+			}
+			fmt.Printf("reading: %v\n", val)
+		case <-quit:
+			return
+		}
+	}
+}