Define DriverInfo and registration helpers

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])
+		}
+	}
+}