Fix the HPET table probe routine to run from device_identify() instead

of directly from acpi0.  Before it would attach prior to the sysresource
devices, causing the later allocation of its memory range to fail and
print a warning like "acpi0: reservation of fed00000, 1000 (3) failed".
Use an explicit define for our probe order base value of 10.

Help from:	jhb
Tested by:	Abdullah Ibn Hamad Al-Marri <almarrie / gmail.com>
MFC after:	3 days
Approved by:	re

sys/dev/acpica/acpi.c

@@ -509,7 +509,6 @@ acpi_attach(device_t dev)
      * a problem but should be addressed eventually.
      */
     acpi_ec_ecdt_probe(dev);
-    acpi_hpet_table_probe(dev);
 
     /* Bring device objects and regions online. */
     if (ACPI_FAILURE(status = AcpiInitializeObjects(flags))) {
@@ -1594,11 +1593,12 @@ acpi_probe_child(ACPI_HANDLE handle, UINT32 level, void *context, void **status)
 	    /* 
 	     * Create a placeholder device for this node.  Sort the placeholder
 	     * so that the probe/attach passes will run breadth-first.  Orders
-	     * less than 10 are reserved for special objects (i.e., system
+	     * less than ACPI_DEV_BASE_ORDER are reserved for special objects
-	     * resources).  Larger values are used for all other devices.
+	     * (i.e., system resources).  Larger values are used for all other
+	     * devices.
 	     */
 	    ACPI_DEBUG_PRINT((ACPI_DB_OBJECTS, "scanning '%s'\n", handle_str));
-	    order = (level + 1) * 10;
+	    order = (level + 1) * ACPI_DEV_BASE_ORDER;
 	    acpi_probe_order(handle, &order);
 	    child = BUS_ADD_CHILD(bus, order, NULL, -1);
 	    if (child == NULL)

sys/dev/acpica/acpi_hpet.c

@@ -83,14 +83,18 @@ hpet_get_timecount(struct timecounter *tc)
 }
 
 /* Discover the HPET via the ACPI table of the same name. */
-void 
+static void 
-acpi_hpet_table_probe(device_t parent)
+acpi_hpet_identify(driver_t *driver, device_t parent)
 {
 	ACPI_TABLE_HPET *hpet;
 	ACPI_TABLE_HEADER *hdr;
 	ACPI_STATUS	status;
 	device_t	child;
 
+	/* Only one HPET device can be added. */
+	if (devclass_get_device(acpi_hpet_devclass, 0))
+		return;
+
 	/* Currently, ID and minimum clock tick info is unused. */
 
 	status = AcpiGetTable(ACPI_SIG_HPET, 1, (ACPI_TABLE_HEADER **)&hdr);
@@ -105,7 +109,7 @@ acpi_hpet_table_probe(device_t parent)
 	if (hpet->Sequence != 0)
 		printf("ACPI HPET table warning: Sequence is non-zero (%d)\n",
 		    hpet->Sequence);
-	child = BUS_ADD_CHILD(parent, 0, "acpi_hpet", 0);
+	child = BUS_ADD_CHILD(parent, ACPI_DEV_BASE_ORDER, "acpi_hpet", 0);
 	if (child == NULL) {
 		printf("%s: can't add child\n", __func__);
 		return;
@@ -115,8 +119,6 @@ acpi_hpet_table_probe(device_t parent)
 	acpi_set_magic(child, (uintptr_t)&acpi_hpet_devclass);
 	bus_set_resource(child, SYS_RES_MEMORY, 0, hpet->Address.Address,
 	    HPET_MEM_WIDTH);
-	if (device_probe_and_attach(child) != 0)
-		device_delete_child(parent, child);
 }
 
 static int
@@ -254,6 +256,7 @@ acpi_hpet_test(struct acpi_hpet_softc *sc)
 
 static device_method_t acpi_hpet_methods[] = {
 	/* Device interface */
+	DEVMETHOD(device_identify, acpi_hpet_identify),
 	DEVMETHOD(device_probe, acpi_hpet_probe),
 	DEVMETHOD(device_attach, acpi_hpet_attach),
 	DEVMETHOD(device_detach, acpi_hpet_detach),

sys/dev/acpica/acpivar.h

@@ -432,8 +432,6 @@ int		acpi_battery_get_battinfo(device_t dev,
 
 /* Embedded controller. */
 void		acpi_ec_ecdt_probe(device_t);
-/* HPET table probe*/
-void		acpi_hpet_table_probe(device_t);
 
 /* AC adapter interface. */
 int		acpi_acad_get_acline(int *);
@@ -449,6 +447,14 @@ int		acpi_PkgGas(device_t dev, ACPI_OBJECT *res, int idx, int *type,
 		    int *rid, struct resource **dst, u_int flags);
 ACPI_HANDLE	acpi_GetReference(ACPI_HANDLE scope, ACPI_OBJECT *obj);
 
+/*
+ * Base level for BUS_ADD_CHILD.  Special devices are added at orders less
+ * than this, and normal devices at or above this level.  This keeps the
+ * probe order sorted so that things like sysresource are available before
+ * their children need them.
+ */
+#define	ACPI_DEV_BASE_ORDER	10
+
 /* Default number of task queue threads to start. */
 #ifndef ACPI_MAX_THREADS
 #define ACPI_MAX_THREADS	3