Merge pull request #47 from achilleasa/order-based-driver-probing

Order based driver detection/loading

src/gopheros/device/driver.go

@@ -22,3 +22,68 @@ type Driver interface {
 // ProbeFn is a function that scans for the presence of a particular
 // piece of hardware and returns a driver for it.
 type ProbeFn func() Driver
+
+// DetectOrder specifies when each driver's probe function will be invoked
+// by the hal package.
+type DetectOrder int8
+
+const (
+	// DetectOrderEarly specifies that the driver's probe function should
+	// be executed at the beginning of the HW detection phase. It is used
+	// by some of the console and TTY device drivers.
+	DetectOrderEarly DetectOrder = -128
+
+	// DetectOrderBeforeACPI specifies that the driver's probe function
+	// should be executed before attempting any ACPI-based HW detection but
+	// after any drivers with DetectOrderEarly.
+	DetectOrderBeforeACPI = -127
+
+	// DetectOrderACPI specifies that the driver's probe function should
+	// be executed after parsing the ACPI tables. This is the default (zero
+	// value) for all drivers.
+	DetectOrderACPI = 0
+
+	// DetectOrderLast specifies that the driver's probe function should
+	// be executed at the end of the HW detection phase.
+	DetectOrderLast = 127
+)
+
+// DriverInfo is a driver-defined struct that is passed to calls to RegisterDriver.
+type DriverInfo struct {
+	// Order specifies at which stage of the HW detection step should
+	// the probe function be invoked.
+	Order DetectOrder
+
+	// Probe is a function that checks for the presence of a particular
+	// piece of hardware and returns back a driver for it.
+	Probe ProbeFn
+}
+
+// DriverInfoList is a list of registered drivers that implements sort.Sort.
+type DriverInfoList []*DriverInfo
+
+// Len returns the length of the driver info list.
+func (l DriverInfoList) Len() int { return len(l) }
+
+// Swap exchanges 2 elements in the driver info list.
+func (l DriverInfoList) Swap(i, j int) { l[i], l[j] = l[j], l[i] }
+
+// Less compares 2 elements of the driver info list.
+func (l DriverInfoList) Less(i, j int) bool { return l[i].Order < l[j].Order }
+
+var (
+	// registeredDrivers tracks the drivers registered via a call to
+	// RegisterDriver.
+	registeredDrivers DriverInfoList
+)
+
+// RegisterDriver adds the supplied driver info to the list of registered
+// drivers.  The list can be retrieved by a call to DriverList().
+func RegisterDriver(info *DriverInfo) {
+	registeredDrivers = append(registeredDrivers, info)
+}
+
+// DriverList returns the list of registered drivers.
+func DriverList() DriverInfoList {
+	return registeredDrivers
+}

src/gopheros/device/driver_test.go

@@ -0,0 +1,36 @@
+package device
+
+import (
+	"sort"
+	"testing"
+)
+
+func TestDriverInfoListSorting(t *testing.T) {
+	defer func() {
+		registeredDrivers = nil
+	}()
+
+	origlist := []*DriverInfo{
+		&DriverInfo{Order: DetectOrderACPI},
+		&DriverInfo{Order: DetectOrderLast},
+		&DriverInfo{Order: DetectOrderBeforeACPI},
+		&DriverInfo{Order: DetectOrderEarly},
+	}
+
+	for _, drv := range origlist {
+		RegisterDriver(drv)
+	}
+
+	registeredList := DriverList()
+	if exp, got := len(origlist), len(registeredList); got != exp {
+		t.Fatalf("expected DriverList() to return %d entries; got %d", exp, got)
+	}
+
+	sort.Sort(registeredList)
+	expOrder := []int{3, 2, 0, 1}
+	for i, exp := range expOrder {
+		if registeredList[i] != origlist[exp] {
+			t.Errorf("expected sorted entry %d to be %v; got %v", i, registeredList[exp], origlist[i])
+		}
+	}
+}

src/gopheros/device/tty/probe.go

@@ -1,11 +0,0 @@
-package tty
-
-import "gopheros/device"
-
-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

@@ -265,5 +265,8 @@ func probeForVT() device.Driver {
 }
 
 func init() {
-	ProbeFuncs = append(ProbeFuncs, probeForVT)
+	device.RegisterDriver(&device.DriverInfo{
+		Order: device.DetectOrderEarly,
+		Probe: probeForVT,
+	})
 }

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

@@ -3,9 +3,18 @@ package console
 import (
 	"gopheros/device/video/console/font"
 	"gopheros/device/video/console/logo"
+	"gopheros/kernel/cpu"
+	"gopheros/kernel/hal/multiboot"
+	"gopheros/kernel/mem/vmm"
 	"image/color"
 )
 
+var (
+	mapRegionFn          = vmm.MapRegion
+	portWriteByteFn      = cpu.PortWriteByte
+	getFramebufferInfoFn = multiboot.GetFramebufferInfo
+)
+
 // ScrollDir defines a scroll direction.
 type ScrollDir uint8
 

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

@@ -1,19 +0,0 @@
-package console
-
-import (
-	"gopheros/device"
-	"gopheros/kernel/cpu"
-	"gopheros/kernel/hal/multiboot"
-	"gopheros/kernel/mem/vmm"
-)
-
-var (
-	mapRegionFn          = vmm.MapRegion
-	portWriteByteFn      = cpu.PortWriteByte
-	getFramebufferInfoFn = multiboot.GetFramebufferInfo
-
-	// 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/vesa_fb.go

@@ -603,5 +603,8 @@ func probeForVesaFbConsole() device.Driver {
 }
 
 func init() {
-	ProbeFuncs = append(ProbeFuncs, probeForVesaFbConsole)
+	device.RegisterDriver(&device.DriverInfo{
+		Order: device.DetectOrderEarly,
+		Probe: probeForVesaFbConsole,
+	})
 }

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

@@ -236,5 +236,8 @@ func probeForVgaTextConsole() device.Driver {
 }
 
 func init() {
-	ProbeFuncs = append(ProbeFuncs, probeForVgaTextConsole)
+	device.RegisterDriver(&device.DriverInfo{
+		Order: device.DetectOrderEarly,
+		Probe: probeForVgaTextConsole,
+	})
 }

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 (
@@ -30,70 +34,20 @@ 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)
 
-		if logoSetter, ok := (devices.activeConsole).(console.LogoSetter); ok {
+	probe(drivers)
-			disableLogo := false
-			for k, v := range multiboot.GetBootCmdLine() {
-				if k == "consoleLogo" && v == "off" {
-					disableLogo = true
-					break
-				}
-			}
-
-			if !disableLogo {
-				consW, consH := devices.activeConsole.Dimensions(console.Pixels)
-				logoSetter.SetLogo(logo.BestFit(consW, consH))
-			}
-		}
-
-		if fontSetter, ok := (devices.activeConsole).(console.FontSetter); ok {
-			consW, consH := devices.activeConsole.Dimensions(console.Pixels)
-
-			// Check boot cmdline for a font request
-			var selFont *font.Font
-			for k, v := range multiboot.GetBootCmdLine() {
-				if k != "consoleFont" {
-					continue
-				}
-
-				if selFont = font.FindByName(v); selFont != nil {
-					break
-				}
-			}
-
-			if selFont == nil {
-				selFont = font.BestFit(consW, consH)
-			}
-
-			fontSetter.SetFont(selFont)
-		}
-	}
-
-	ttys := probe(tty.ProbeFuncs)
-	if len(ttys) != 0 {
-		devices.activeTTY = ttys[0].(tty.Device)
-		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
+// probe executes the probe function for each driver and invokes
-// each detected device. The function returns a list of device drivers that
+// onDriverInit for each successfully initialized driver.
-// were successfully initialized.
+func probe(driverInfoList device.DriverInfoList) {
-func probe(hwProbeFns []device.ProbeFn) []device.Driver {
+	var w = kfmt.PrefixWriter{Sink: kfmt.GetOutputSink()}
-	var (
-		drivers []device.Driver
-		w       = kfmt.PrefixWriter{Sink: kfmt.GetOutputSink()}
-	)
 
-	for _, probeFn := range hwProbeFns {
+	for _, info := range driverInfoList {
-		drv := probeFn()
+		drv := info.Probe()
 		if drv == nil {
 			continue
 		}
@@ -109,8 +63,91 @@ func probe(hwProbeFns []device.ProbeFn) []device.Driver {
 		}
 
 		kfmt.Fprintf(&w, "initialized\n")
-		drivers = append(drivers, drv)
+		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
 	}
 
-	return drivers
+	devices.activeConsole = cons
+
+	if logoSetter, ok := (devices.activeConsole).(console.LogoSetter); ok {
+		disableLogo := false
+		for k, v := range multiboot.GetBootCmdLine() {
+			if k == "consoleLogo" && v == "off" {
+				disableLogo = true
+				break
+			}
+		}
+
+		if !disableLogo {
+			consW, consH := devices.activeConsole.Dimensions(console.Pixels)
+			logoSetter.SetLogo(logo.BestFit(consW, consH))
+		}
+	}
+
+	if fontSetter, ok := (devices.activeConsole).(console.FontSetter); ok {
+		consW, consH := devices.activeConsole.Dimensions(console.Pixels)
+
+		// Check boot cmdline for a font request
+		var selFont *font.Font
+		for k, v := range multiboot.GetBootCmdLine() {
+			if k != "consoleFont" {
+				continue
+			}
+
+			if selFont = font.FindByName(v); selFont != nil {
+				break
+			}
+		}
+
+		if selFont == nil {
+			selFont = font.BestFit(consW, consH)
+		}
+
+		fontSetter.SetFont(selFont)
+	}
+
+	if devices.activeTTY != nil {
+		linkTTYToConsole()
+	}
+}
+
+// linkTTYToConsole connects the active TTY device to the active console device
+// and syncs their contents.
+func linkTTYToConsole() {
+	devices.activeTTY.AttachTo(devices.activeConsole)
+	kfmt.SetOutputSink(devices.activeTTY)
+
+	// Sync terminal contents with console
+	devices.activeTTY.SetState(tty.StateActive)
+
 }