Allow device hints to wire the unit numbers of devices.

- An "at" hint now reserves a device name.
- A new BUS_HINT_DEVICE_UNIT method is added to the bus interface.  When
  determining the unit number of a device, this method is invoked to
  let the bus driver specify the unit of a device given a specific
  devclass.  This is the only way a device can be given a name reserved
  via an "at" hint.
- Implement BUS_HINT_DEVICE_UNIT() for the acpi(4) and isa(4) bus drivers.
  Both of these busses implement this by comparing the resources for a
  given hint device with the resources enumerated by ACPI/PnPBIOS and
  wire a unit if the hint resources are a subset of the "real" resources.
- Use bus_hinted_children() for adding hinted devices on isa(4) busses
  now instead of doing it by hand.
- Remove the unit kludging from sio(4) as it is no longer necessary.

Prodding from:	peter, imp
OK'd by:	marcel
MFC after:	1 month

1 files changed, 3 insertions, 0 deletions

diff --git a/sys/isa/isavar.h b/sys/isa/isavar.h
index 59d3bc9..3b1a2e6 100644
--- a/sys/isa/isavar.h
+++ b/sys/isa/isavar.h
@@ -181,6 +181,9 @@ int	isa_dmatc(int chan);
 		    (int)(chan), (uintmax_t)(size)); \
 	} while (0) 
 
+void	isa_hinted_child(device_t parent, const char *name, int unit);
+void	isa_hint_device_unit(device_t bus, device_t child, const char *name,
+	    int *unitp);
 int	isab_attach(device_t dev);
 
 #ifdef PC98