Each driver should manually register a probe function for use by hal

This commit removes the HWProbes() function from the console and tty
packages and replaces it with a global ProbeFuncs slice which is fetched
by the hal package when the hardware autodetection code runs.

Each driver should provide an init() function that appends a probe function
to the global ProbeFuncs slice.

This approach allows us to support conditional compilation of drivers in
the future (e.g. using build tags)

src/gopheros/device/tty/probe.go

@@ -2,10 +2,10 @@ package tty
 
 import "gopheros/device"
 
-// HWProbes returns a slice of device.ProbeFn that can be used by the hal
-// package to probe for TTY device hardware.
-func HWProbes() []device.ProbeFn {
-	return []device.ProbeFn{
-		probeForVT,
-	}
-}
+var (
+	// ProbeFuncs is a slice of device probe functions
+	// that is used by the hal package to probe for TTY
+	// hardware. Each driver should use an init() block
+	// to append its probe function to this list.
+	ProbeFuncs []device.ProbeFn
+)

src/gopheros/device/tty/vt.go

@@ -260,6 +260,8 @@ func (t *VT) DriverVersion() (uint16, uint16, uint16) {
 // DriverInit initializes this driver.
 func (t *VT) DriverInit() *kernel.Error { return nil }
 
-func probeForVT() device.Driver {
-	return NewVT(DefaultTabWidth, DefaultScrollback)
+func init() {
+	ProbeFuncs = append(ProbeFuncs, func() device.Driver {
+		return NewVT(DefaultTabWidth, DefaultScrollback)
+	})
 }

src/gopheros/device/video/console/probe.go

@@ -5,12 +5,9 @@ import "gopheros/kernel/hal/multiboot"
 
 var (
 	getFramebufferInfoFn = multiboot.GetFramebufferInfo
-)
 
-// HWProbes returns a slice of device.ProbeFn that can be used by the hal
-// package to probe for console device hardware.
-func HWProbes() []device.ProbeFn {
-	return []device.ProbeFn{
-		probeForVgaTextConsole,
-	}
-}
+	// ProbeFuncs is a slice of device probe functions that is used by
+	// the hal package to probe for console device hardware. Each driver
+	// should use an init() block to append its probe function to this list.
+	ProbeFuncs []device.ProbeFn
+)

src/gopheros/device/video/console/vga_text.go

@@ -199,14 +199,15 @@ func (cons *VgaTextConsole) DriverVersion() (uint16, uint16, uint16) {
 // DriverInit initializes this driver.
 func (cons *VgaTextConsole) DriverInit() *kernel.Error { return nil }
 
-// probeForVgaTextConsole checks for the presence of a vga text console.
-func probeForVgaTextConsole() device.Driver {
-	var drv device.Driver
+func init() {
+	ProbeFuncs = append(ProbeFuncs, func() device.Driver {
+		var drv device.Driver
 
-	fbInfo := getFramebufferInfoFn()
-	if fbInfo.Type == multiboot.FramebufferTypeEGA {
-		drv = NewVgaTextConsole(fbInfo.Width, fbInfo.Height, uintptr(fbInfo.PhysAddr))
-	}
+		fbInfo := getFramebufferInfoFn()
+		if fbInfo.Type == multiboot.FramebufferTypeEGA {
+			drv = NewVgaTextConsole(fbInfo.Width, fbInfo.Height, uintptr(fbInfo.PhysAddr))
+		}
 
-	return drv
+		return drv
+	})
 }

src/gopheros/kernel/hal/hal.go

@@ -23,12 +23,12 @@ func ActiveTTY() tty.Device {
 // DetectHardware probes for hardware devices and initializes the appropriate
 // drivers.
 func DetectHardware() {
-	consoles := probe(console.HWProbes())
+	consoles := probe(console.ProbeFuncs)
 	if len(consoles) != 0 {
 		devices.activeConsole = consoles[0].(console.Device)
 	}
 
-	ttys := probe(tty.HWProbes())
+	ttys := probe(tty.ProbeFuncs)
 	if len(ttys) != 0 {
 		devices.activeTTY = ttys[0].(tty.Device)
 		devices.activeTTY.AttachTo(devices.activeConsole)