[inky] Add Inky Impression 5.7" and 4" support (#55)

It is a 7 colour ePaper/eInk HAT that comes with 5.7" (600 x 448 pixel) or 4" (640 x 400 pixel).

Refactors the existing 3 color Inky and adds additional fields to
auto-detect via EEPROM.

Tested with 5.7" version.

.github/workflows/test.yml

@@ -128,6 +128,7 @@ jobs:
         go install github.com/securego/gosec/v2/cmd/gosec@latest
         go install golang.org/x/tools/go/analysis/passes/shadow/cmd/shadow@latest
         go install honnef.co/go/tools/cmd/staticcheck@latest
+        go install golang.org/x/tools/cmd/stringer@latest
     - name: 'go install necessary tools (ubuntu)'
       if: always() && matrix.os == 'ubuntu-latest'
       run: |

inky/example_test.go

@@ -12,6 +12,7 @@ import (
 	"os"
 
 	"periph.io/x/conn/v3/gpio/gpioreg"
+	"periph.io/x/conn/v3/i2c/i2creg"
 	"periph.io/x/conn/v3/spi/spireg"
 	"periph.io/x/devices/v3/inky"
 	"periph.io/x/host/v3"
@@ -58,3 +59,52 @@ func Example() {
 		log.Fatal(err)
 	}
 }
+
+func ExampleNewImpression() {
+	path := flag.String("image", "", "Path to image file (600x448) to display")
+	flag.Parse()
+
+	f, err := os.Open(*path)
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer f.Close()
+
+	m, _, err := image.Decode(f)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	if _, err = host.Init(); err != nil {
+		log.Fatal(err)
+	}
+
+	b, err := spireg.Open("SPI0.0")
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	dc := gpioreg.ByName("22")
+	reset := gpioreg.ByName("27")
+	busy := gpioreg.ByName("17")
+
+	eeprom, err := i2creg.Open("")
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer eeprom.Close()
+
+	o, err := inky.DetectOpts(eeprom)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	dev, err := inky.NewImpression(b, dc, reset, busy, o)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	if err := dev.Draw(m.Bounds(), m, image.Point{}); err != nil {
+		log.Fatal(err)
+	}
+}