PinInput+PinOutput HAL (#753, reloaded) (#795)

* first commit: add HAL and uc8151 driver demo
* unexport drivers.PinOutput/Input HAL
* fix non-tinygo pin config build
* change of heart
* docs: corrected some comments that were not changed at the same time as recent renaming

internal/legacy/pinconfig.go

@@ -0,0 +1,62 @@
+package legacy
+
+import (
+	"errors"
+
+	"tinygo.org/x/drivers/internal/pin"
+)
+
+// The pingconfig group of files serve to abstract away
+// pin configuration calls on the machine.Pin type.
+// It was observed this way of developing drivers was
+// non-portable and unusable on "big" Go projects so
+// future projects should NOT configure pins in driver code.
+// Users must configure pins before passing them as arguments
+// to drivers.
+
+// ConfigurePinOut is a legacy function used to configure pins as outputs.
+//
+// Deprecated: Do not configure pins in drivers.
+// This is a legacy feature and should only be used by drivers that
+// previously configured pins in initialization to avoid breaking users.
+func ConfigurePinOut(po pin.Output) {
+	configurePinOut(po)
+}
+
+// ConfigurePinInput is a legacy function used to configure pins as inputs.
+//
+// Deprecated: Do not configure pins in drivers.
+// This is a legacy feature and should only be used by drivers that
+// previously configured pins in initialization to avoid breaking users.
+func ConfigurePinInputPulldown(pi pin.Input) {
+	configurePinInputPulldown(pi)
+}
+
+// ConfigurePinInput is a legacy function used to configure pins as inputs.
+//
+// Deprecated: Do not configure pins in drivers.
+// This is a legacy feature and should only be used by drivers that
+// previously configured pins in initialization to avoid breaking users.
+func ConfigurePinInput(pi pin.Input) {
+	configurePinInput(pi)
+}
+
+// ConfigurePinInput is a legacy function used to configure pins as inputs.
+//
+// Deprecated: Do not configure pins in drivers.
+// This is a legacy feature and should only be used by drivers that
+// previously configured pins in initialization to avoid breaking users.
+func ConfigurePinInputPullup(pi pin.Input) {
+	configurePinInputPullup(pi)
+}
+
+// PinIsNoPin returns true if the argument is a machine.Pin type and is the machine.NoPin predeclared type.
+//
+// Deprecated: Drivers do not require pin knowledge from now on.
+func PinIsNoPin(pin any) bool {
+	return pinIsNoPin(pin)
+}
+
+var (
+	ErrConfigBeforeInstantiated = errors.New("device must be instantiated with New before calling Configure method")
+)

internal/legacy/pinconfig_go.go

@@ -0,0 +1,15 @@
+//go:build !tinygo
+
+package legacy
+
+import "tinygo.org/x/drivers/internal/pin"
+
+// This file compiles for non-tinygo builds
+// for use with "big" or "upstream" Go where
+// there is no machine package.
+
+func configurePinOut(p pin.Output)          {}
+func configurePinInput(p pin.Input)         {}
+func configurePinInputPulldown(p pin.Input) {}
+func configurePinInputPullup(p pin.Input)   {}
+func pinIsNoPin(a any) bool                 { return false }

internal/legacy/pinconfig_nopulls.go

@@ -0,0 +1,10 @@
+//go:build baremetal && fe310
+
+package legacy
+
+import "machine"
+
+const (
+	pulldown = machine.PinInput
+	pullup   = machine.PinInput
+)

internal/legacy/pinconfig_pulls.go

@@ -0,0 +1,13 @@
+//go:build baremetal && !fe310
+
+package legacy
+
+import "machine"
+
+// If you are getting a build error here you then we missed adding
+// your CPU build tag to the list of CPUs that do not have pulldown/pullups.
+// Add it above and in pinhal_nopulls! You should also add a smoketest for it :)
+const (
+	pulldown = machine.PinInputPulldown
+	pullup   = machine.PinInputPullup
+)

internal/legacy/pinconfig_tinygo.go

@@ -0,0 +1,37 @@
+//go:build baremetal
+
+package legacy
+
+import (
+	"machine"
+
+	"tinygo.org/x/drivers/internal/pin"
+)
+
+func configurePinOut(po pin.Output) {
+	configurePin(po, machine.PinOutput)
+}
+
+func configurePinInputPulldown(pi pin.Input) {
+	configurePin(pi, pulldown) // some chips do not have pull down, in which case pulldown==machine.PinInput.
+}
+
+func configurePinInput(pi pin.Input) {
+	configurePin(pi, machine.PinInput)
+}
+
+func configurePinInputPullup(pi pin.Input) {
+	configurePin(pi, pullup) // some chips do not have pull up, in which case pullup==machine.PinInput.
+}
+
+func pinIsNoPin(a any) bool {
+	p, ok := a.(machine.Pin)
+	return ok && p == machine.NoPin
+}
+
+func configurePin(p any, mode machine.PinMode) {
+	machinePin, ok := p.(machine.Pin)
+	if ok {
+		machinePin.Configure(machine.PinConfig{Mode: mode})
+	}
+}