First implementation

vendor/periph.io/x/periph/conn/pin/pin.go

@@ -0,0 +1,139 @@
+// Copyright 2016 The Periph Authors. All rights reserved.
+// Use of this source code is governed under the Apache License, Version 2.0
+// that can be found in the LICENSE file.
+
+// Package pin declare well known pins.
+//
+// pin is about physical pins, not about their logical function.
+//
+// While not a protocol strictly speaking, these are "well known constants".
+package pin
+
+import (
+	"errors"
+
+	"periph.io/x/periph/conn"
+)
+
+// These are well known pins.
+var (
+	INVALID  *BasicPin // Either floating or invalid pin
+	GROUND   *BasicPin // Ground
+	V1_8     *BasicPin // 1.8V (filtered)
+	V2_8     *BasicPin // 2.8V (filtered)
+	V3_3     *BasicPin // 3.3V (filtered)
+	V5       *BasicPin // 5V (filtered)
+	DC_IN    *BasicPin // DC IN; this is normally the 5V input
+	BAT_PLUS *BasicPin // LiPo Battery + connector
+)
+
+// Pin is the minimal common interface shared between gpio.PinIO and
+// analog.PinIO.
+type Pin interface {
+	conn.Resource
+	// Name returns the name of the pin.
+	Name() string
+	// Number returns the logical pin number or a negative number if the pin is
+	// not a GPIO, e.g. GROUND, V3_3, etc.
+	Number() int
+	// Function returns a user readable string representation of what the pin is
+	// configured to do. Common case is In and Out but it can be bus specific pin
+	// name.
+	//
+	// Deprecated: Use PinFunc.Func. Will be removed in v4.
+	Function() string
+}
+
+// PinFunc is a supplementary interface that enables specifically querying for
+// the pin function.
+//
+// TODO(maruel): It will be merged into interface Pin for v4.
+type PinFunc interface {
+	// Func returns the pin's current function.
+	//
+	// The returned value may be specialized or generalized, depending on the
+	// actual port. For example it will likely be generalized for ports served
+	// over USB (like a FT232H with D0 set as SPI_MOSI) but specialized for
+	// ports on the base board (like a RPi3 with GPIO10 set as SPI0_MOSI).
+	Func() Func
+	// SupportedFuncs returns the possible functions this pin support.
+	//
+	// Do not mutate the returned slice.
+	SupportedFuncs() []Func
+	// SetFunc sets the pin function.
+	//
+	// Example use is to reallocate a RPi3's GPIO14 active function between
+	// UART0_TX and UART1_TX.
+	SetFunc(f Func) error
+}
+
+//
+
+// BasicPin implements Pin as a static pin.
+//
+// It doesn't have a usable functionality.
+type BasicPin struct {
+	N string
+}
+
+// String implements conn.Resource.
+func (b *BasicPin) String() string {
+	return b.N
+}
+
+// Halt implements conn.Resource.
+func (b *BasicPin) Halt() error {
+	return nil
+}
+
+// Name implements Pin.
+func (b *BasicPin) Name() string {
+	return b.N
+}
+
+// Number implements Pin.
+//
+// Returns -1 as pin number.
+func (b *BasicPin) Number() int {
+	return -1
+}
+
+// Function implements Pin.
+//
+// Returns "" as pin function.
+func (b *BasicPin) Function() string {
+	return ""
+}
+
+// Func implements PinFunc.
+//
+// Returns FuncNone as pin function.
+func (b *BasicPin) Func() Func {
+	return FuncNone
+}
+
+// SupportedFuncs implements PinFunc.
+//
+// Returns nil.
+func (b *BasicPin) SupportedFuncs() []Func {
+	return nil
+}
+
+// SetFunc implements PinFunc.
+func (b *BasicPin) SetFunc(f Func) error {
+	return errors.New("pin: can't change static pin function")
+}
+
+func init() {
+	INVALID = &BasicPin{N: "INVALID"}
+	GROUND = &BasicPin{N: "GROUND"}
+	V1_8 = &BasicPin{N: "1.8V"}
+	V2_8 = &BasicPin{N: "2.8V"}
+	V3_3 = &BasicPin{N: "3.3V"}
+	V5 = &BasicPin{N: "5V"}
+	DC_IN = &BasicPin{N: "DC_IN"}
+	BAT_PLUS = &BasicPin{N: "BAT+"}
+}
+
+var _ Pin = INVALID
+var _ PinFunc = INVALID