bcm283x: fix invalid aliasing; causing failure on RPi1 and RPi Zero

The regression was introduced in
3d9b008, so version v3.2.0 up to v3.6.0
are affected.

Add smoketest to catch regressions. Manually tested on a RPi1 and RPiZW.

Fixes google#420

.gohci.yml

@@ -226,6 +226,10 @@ workers:
     - P1_15
     - -pin2
     - P1_16
+  - cmd:
+    - periph-smoketest
+    - bcm283x
+    - -quick
 # Laptop on Windows 10.
 - name: win10
   checks:

host/bcm283x/bcm283xsmoketest/bcm283xsmoketest.go

@@ -13,9 +13,11 @@ import (
 	"flag"
 	"fmt"
 	"reflect"
+	"regexp"
 	"time"
 
 	"periph.io/x/periph/conn/gpio"
+	"periph.io/x/periph/conn/gpio/gpioreg"
 	"periph.io/x/periph/conn/gpio/gpiostream"
 	"periph.io/x/periph/conn/physic"
 	"periph.io/x/periph/conn/pin"
@@ -35,11 +37,12 @@ func (s *SmokeTest) Name() string {
 
 // Description implements the SmokeTest interface.
 func (s *SmokeTest) Description() string {
-	return "Tests advanced bcm283x functionality"
+	return "Tests advanced bcm283x functionality with GPIO6 and GPIO13"
 }
 
 // Run implements the SmokeTest interface.
 func (s *SmokeTest) Run(f *flag.FlagSet, args []string) error {
+	quick := f.Bool("quick", false, "Skip tests requiring DMA")
 	if err := f.Parse(args); err != nil {
 		return err
 	}
@@ -52,6 +55,13 @@ func (s *SmokeTest) Run(f *flag.FlagSet, args []string) error {
 		return errors.New("this smoke test can only be run on a bcm283x based host")
 	}
 
+	if err := testAliases(); err != nil {
+		return err
+	}
+	if *quick {
+		return nil
+	}
+
 	start := time.Now()
 	pClk := &loggingPin{bcm283x.GPIO6, start}
 	pPWM := &loggingPin{bcm283x.GPIO13, start}
@@ -231,6 +241,59 @@ func (s *SmokeTest) testStreamIn(p1, p2 *loggingPin) (err error) {
 
 //
 
+// testAliases catches unexpected GPIO aliases.
+func testAliases() error {
+	expectedStr := []string{
+		`\d+`,
+		`GPIO\d+`,
+		`AUDIO_\d`,
+		`CLK\d`,
+		`GPCLK\d`,
+		`HDMI_\d`,
+		`I2C\d_SCL`,
+		`I2C\d_SDA`,
+		`I2S_DIN`,
+		`I2S_DOUT`,
+		`I2S_SCK`,
+		`I2S_WS`,
+		`P1_\d+`,
+		`P5_\d+`,
+		`PWM\d`,
+		`PWM\d_OUT`,
+		`SPI\d_CLK`,
+		`SPI\d_CS\d`,
+		`SPI\d_MISO`,
+		`SPI\d_MOSI`,
+		`UART\d_CTS`,
+		`UART\d_RTS`,
+		`UART\d_RX`,
+		`UART\d_TX`,
+	}
+	valid := make([]*regexp.Regexp, 0, len(expectedStr))
+	for i, v := range expectedStr {
+		r, err := regexp.Compile("^" + v + "$")
+		if err != nil {
+			return fmt.Errorf("Accepted #%d is invalid: %q", i, v)
+		}
+		valid = append(valid, r)
+	}
+
+	for _, p := range gpioreg.Aliases() {
+		n := p.Name()
+		ok := false
+		for _, r := range valid {
+			if r.MatchString(n) {
+				ok = true
+				break
+			}
+		}
+		if !ok {
+			return fmt.Errorf("Found unexpected alias %q", n)
+		}
+	}
+	return nil
+}
+
 func printPin(p gpio.PinIO) {
 	fmt.Printf("- %s: %s", p, p.Function())
 	if r, ok := p.(gpio.RealPin); ok {

host/bcm283x/gpio.go

@@ -1255,7 +1255,7 @@ func (d *driverGPIO) Init() (bool, error) {
 			return true, err
 		}
 		switch f := cpuPins[i].Func(); f {
-		case gpio.IN, gpio.OUT:
+		case gpio.IN, gpio.OUT, gpio.IN_LOW, gpio.IN_HIGH, gpio.OUT_LOW, gpio.OUT_HIGH, pin.FuncNone:
 		default:
 			// Registering the same alias twice fails. This can happen if two pins
 			// are configured with the same function. For example both pin #12, #18