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vendor/periph.io/x/host/v3/allwinner/detect.go

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+// Copyright 2022 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 allwinner
+
+import (
+	"strings"
+	"sync"
+
+	"periph.io/x/host/v3/distro"
+)
+
+// Present detects whether the host CPU is an Allwinner CPU.
+//
+// https://en.wikipedia.org/wiki/Allwinner_Technology
+func Present() bool {
+	detection.do()
+	return detection.isAllwinner
+}
+
+// IsR8 detects whether the host CPU is an Allwinner R8 CPU.
+//
+// It looks for the string "sun5i-r8" in /proc/device-tree/compatible.
+func IsR8() bool {
+	detection.do()
+	return detection.isR8
+}
+
+// IsA20 detects whether the host CPU is an Allwinner A20 CPU.
+//
+// It first looks for the string "sun71-a20" in /proc/device-tree/compatible,
+// and if that fails it checks for "Hardware : sun7i" in /proc/cpuinfo.
+func IsA20() bool {
+	detection.do()
+	return detection.isA20
+}
+
+// IsA64 detects whether the host CPU is an Allwinner A64 CPU.
+//
+// It looks for the string "sun50iw1p1" in /proc/device-tree/compatible.
+func IsA64() bool {
+	detection.do()
+	return detection.isA64
+}
+
+// IsH3 detects whether the host CPU is an Allwinner H3/H2+ Plus CPU.
+//
+// It looks for the string "sun8i-h2-plus" or "sun8i-h3" in /proc/device-tree/compatible.
+func IsH3() bool {
+	detection.do()
+	return detection.isH3
+}
+
+// IsH5 detects whether the host CPU is an Allwinner H5 CPU.
+//
+// It looks for the string "sun50i-h5" in /proc/device-tree/compatible.
+func IsH5() bool {
+	detection.do()
+	return detection.isH5
+}
+
+//
+
+type detectionS struct {
+	mu          sync.Mutex
+	done        bool
+	isAllwinner bool
+	isR8        bool
+	isA20       bool
+	isA64       bool
+	isH3        bool
+	isH5        bool
+}
+
+var detection detectionS
+
+// do contains the CPU detection logic that determines whether we have an
+// Allwinner CPU and if so, which exact model.
+//
+// Sadly there is no science behind this, it's more of a trial and error using
+// as many boards and OS flavors as possible.
+func (d *detectionS) do() {
+	d.mu.Lock()
+	defer d.mu.Unlock()
+	if !d.done {
+		d.done = true
+		if isArm {
+			for _, c := range distro.DTCompatible() {
+				if strings.Contains(c, "sun50iw1p1") {
+					d.isA64 = true
+				}
+				if strings.Contains(c, "sun5i-r8") {
+					d.isR8 = true
+				}
+				if strings.Contains(c, "sun7i-a20") {
+					d.isA20 = true
+				}
+				// H2+ is a subtype of H3 and nearly compatible (only lacks GBit MAC and
+				// 4k HDMI Output), so it is safe to map H2+ as an H3.
+				if strings.Contains(c, "sun8i-h2-plus") || strings.Contains(c, "sun8i-h3") {
+					d.isH3 = true
+				}
+				if strings.Contains(c, "sun50i-h5") {
+					d.isH5 = true
+				}
+			}
+			d.isAllwinner = d.isA64 || d.isR8 || d.isA20 || d.isH3 || d.isH5
+
+			if !d.isAllwinner {
+				// The kernel in the image that comes pre-installed on the pcDuino3 Nano
+				// is an old 3.x kernel that doesn't expose the device-tree in procfs,
+				// so do an extra check in cpuinfo as well if we haven't detected
+				// anything yet.
+				// Distros based on 4.x kernels do expose it.
+				if hw, ok := distro.CPUInfo()["Hardware"]; ok {
+					if hw == "sun7i" {
+						d.isA20 = true
+					}
+				}
+			}
+		}
+	}
+}