that their child busses can be attached after the PCI bus
autoconfiguration for their parent bus is done.
This works because:
(1) there can be at most one ISA/EISA bridge per PCI bus, and
(2) any ISA/EISA bridges must be attached to primary PCI
busses (i.e. bus zero).
That boils down to: there can only be one of these outstanding
at a time, it is cleared when configuring PCI bus 0 before any
subdevices have been found, and it is run after all subdevices
of PCI bus 0 have been found.
This (or something like it) is needed because there are some (legacy)
PCI devices which can show up as ISA/EISA devices as well (the prime
example of which are VGA controllers). If you attach ISA from a
PCI-ISA/EISA bridge, and the bridge is seen before the video board is,
the board can show up as an ISA device, and that can (bogusly)
complicate the PCI device's attach code, or make the PCI device not be
properly attached at all.
This could be done with machine-dependent code, but as more ports
add support for PCI (and PCI-ISA/EISA bridges) more will need it.
The i386 port could (perhaps should) be converted to use it as well.
- No more distinction between i/o-mapped and memory-mapped
devices. It's all "bus space" now, and space tags
differentiate the space with finer grain than the
bus chipset tag.
- Add memory barrier methods.
- Implement space alloc/free methods.
- Implement region read/write methods (like memcpy to/from
bus space).
This interface provides a better abstraction for dealing with
machine-independent chipset drivers.
(soon to be documented on mailing lists; eventually in section 9 manual
pages), most importantly:
(1) support interrupt pin swizzling on non-i386 systems with
PCI-PCI bridges (per PPB spec; done, but meaningless, on i386).
(2) provide pci_{io,mem}_find(), to determine what I/O or memory
space is described by a given PCI configuration space
mapping register.
(3) provide pci_intr_map(), pci_intr_string(), and
pci_intr_{,dis}establish() to manipulate and print info about
PCI interrupts.
(4) make pci functions take as an argument a machine-dependent
cookie, to allow more flexibility in implementation.
pcibus and pci.
(2) remove the #ifdef i386 from pci.c, and provide a machine-dependent
hook (pci_md_attach_hook()) to do any machine-dependent attachment
gunk, e.g. on the i386 printing out the configuration mode (if bus 0)
(3) don't pass max device number for a given bus in, use
PCI_MAX_DEVICE_NUMBER, which can be defined on a per-machine basis.
(defaults to 32. on i386, it's 32 if pci conf mode == 1, 16 if 2.)
attaching, and to the devices when attaching them. #include <machine/bus.h>
to make this backward compatible with old #include requirements.
Also, clean up idempotency so that isa/eisa/pci "var.h" headers are
consistent (make them all idempotent).
(1) remove the 'UNSUPP' keyword from the device list,
because it can't be reasonably used (becuase different
devices may be supported on different machines, for
good reason).
(2) enhance pci_devinfo so that class/subclass information
is optional (so pci_devinfo can be used by drivers that
match classes of devices, and want to look up the
devices' names easily).
(3) more known vendors and devices.
(pci_attach_subdev()). remove pciattach() function and the pcicd cfdriver
struct, the former because thre are a lot of attachment actions which really
are machine-dependent (perhaps even "most"), and the latter because now that
both pcimatch() and pciattach() are machine-dependent it's bad style to
declare them here and it gains nothing.
