Refactor hal code to use preferred driver detection order

src/gopheros/kernel/hal/hal.go

@@ -9,12 +9,16 @@ import (
 	"gopheros/device/video/console/logo"
 	"gopheros/kernel/hal/multiboot"
 	"gopheros/kernel/kfmt"
+	"sort"
 )
 
 // managedDevices contains the devices discovered by the HAL.
 type managedDevices struct {
 	activeConsole console.Device
 	activeTTY     tty.Device
+
+	// activeDrivers tracks all initialized device drivers.
+	activeDrivers []device.Driver
 }
 
 var (
@@ -30,9 +34,70 @@ func ActiveTTY() tty.Device {
 // DetectHardware probes for hardware devices and initializes the appropriate
 // drivers.
 func DetectHardware() {
-	consoles := probe(console.ProbeFuncs)
+	// Get driver list and sort by detection priority
-	if len(consoles) != 0 {
+	drivers := device.DriverList()
-		devices.activeConsole = consoles[0].(console.Device)
+	sort.Sort(drivers)
+
+	probe(drivers)
+}
+
+// probe executes the probe function for each driver and invokes
+// onDriverInit for each successfully initialized driver.
+func probe(driverInfoList device.DriverInfoList) {
+	var w = kfmt.PrefixWriter{Sink: kfmt.GetOutputSink()}
+
+	for _, info := range driverInfoList {
+		drv := info.Probe()
+		if drv == nil {
+			continue
+		}
+
+		strBuf.Reset()
+		major, minor, patch := drv.DriverVersion()
+		kfmt.Fprintf(&strBuf, "[hal] %s(%d.%d.%d): ", drv.DriverName(), major, minor, patch)
+		w.Prefix = strBuf.Bytes()
+
+		if err := drv.DriverInit(&w); err != nil {
+			kfmt.Fprintf(&w, "init failed: %s\n", err.Message)
+			continue
+		}
+
+		kfmt.Fprintf(&w, "initialized\n")
+		onDriverInit(info, drv)
+		devices.activeDrivers = append(devices.activeDrivers, drv)
+	}
+}
+
+// onDriverInit is invoked by probe() whenever a piece of hardware is detected
+// and successfully initialized.
+func onDriverInit(info *device.DriverInfo, drv device.Driver) {
+	switch drvImpl := drv.(type) {
+	case console.Device:
+		onConsoleInit(drvImpl)
+	case tty.Device:
+		if devices.activeTTY != nil {
+			return
+		}
+
+		devices.activeTTY = drvImpl
+		if devices.activeConsole != nil {
+			linkTTYToConsole()
+		}
+	}
+}
+
+// onConsoleInit is invoked whenever a console is initialized. If this is the
+// first found console it automatically becomes the active console. In
+// addition, if the console supports fonts and/or logos this function ensures
+// that they are loaded and attached to the console. Finally, if an active TTY
+// device is present, it will be automatically linked to the first active
+// console via a call to linkTTYToConsole.
+func onConsoleInit(cons console.Device) {
+	if devices.activeConsole != nil {
+		return
+	}
+
+	devices.activeConsole = cons
 
 	if logoSetter, ok := (devices.activeConsole).(console.LogoSetter); ok {
 		disableLogo := false
@@ -70,47 +135,19 @@ func DetectHardware() {
 
 		fontSetter.SetFont(selFont)
 	}
+
+	if devices.activeTTY != nil {
+		linkTTYToConsole()
+	}
 }
 
-	ttys := probe(tty.ProbeFuncs)
+// linkTTYToConsole connects the active TTY device to the active console device
-	if len(ttys) != 0 {
+// and syncs their contents.
-		devices.activeTTY = ttys[0].(tty.Device)
+func linkTTYToConsole() {
 	devices.activeTTY.AttachTo(devices.activeConsole)
 	kfmt.SetOutputSink(devices.activeTTY)
 
 	// Sync terminal contents with console
 	devices.activeTTY.SetState(tty.StateActive)
-	}
-}
 
-// probe executes the supplied hw probe functions and attempts to initialize
-// each detected device. The function returns a list of device drivers that
-// were successfully initialized.
-func probe(hwProbeFns []device.ProbeFn) []device.Driver {
-	var (
-		drivers []device.Driver
-		w       = kfmt.PrefixWriter{Sink: kfmt.GetOutputSink()}
-	)
-
-	for _, probeFn := range hwProbeFns {
-		drv := probeFn()
-		if drv == nil {
-			continue
-		}
-
-		strBuf.Reset()
-		major, minor, patch := drv.DriverVersion()
-		kfmt.Fprintf(&strBuf, "[hal] %s(%d.%d.%d): ", drv.DriverName(), major, minor, patch)
-		w.Prefix = strBuf.Bytes()
-
-		if err := drv.DriverInit(&w); err != nil {
-			kfmt.Fprintf(&w, "init failed: %s\n", err.Message)
-			continue
-		}
-
-		kfmt.Fprintf(&w, "initialized\n")
-		drivers = append(drivers, drv)
-	}
-
-	return drivers
 }