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SubjectRe: devicefs requests

> 1) As new drivers pick up the model, check that all xxx_bus_type objects
> get EXPORT_SYMBOLd and included in a include/xxxx header somewhere - My BIOS
> EDD code walks the list of bus types looking for attached devices to compare
> against (pci, ide, scsi, usb, ...).
> ide_bus_type is in include/linux/ide.h but isn't EXPORT_SYMBOL;
> usb_bus_type is in include/linux/usb.h but isn't EXPORT_SYMBOL;

Yes, sorry about that. I think I've added most of them, and forgot to
export them..

> Alternately, keep the list of registered bus types accessible via a
> list_for_each type macro. I like the exported symbols myself, it lets me
> do:

There is a master bus list: bus_drivers_list in drivers/base/bus.c. It
could easily be exportable, and may be a good idea for you firmware

> static const struct edd_known_bus_types_s edd_known_bus_types[] = {
> {bus:&scsi_driverfs_bus_type, edd_type: "SCSI", match:
> edd_match_scsidev},
> // {bus:&ide_bus_type, edd_type: "ATA", match: NULL},
> // {bus:&usb_bus_type, edd_type: "USB", match: NULL},
> {bus:NULL, edd_type: NULL, match: NULL},
> };
> so I can supply my own match functions which match one type of device (e.g.
> EDD's idea of a SCSI device) to that of the standard device. I could
> accomplish the same using well-known names for bus_type I suppose, and doing
> a list_for_each until I find it. Just a different thing getting exported, a
> well-known name and a lookup method rather than the symbol itself.

Don't rely on the name, as it could change. It could, but at least the
compiler will warn you..

> 2) bus_for_each_dev() is really restrictive right now due to all the locking
> mechanisms in place. In my code I'd like to, given a struct device *, walk
> a list of devices on a given bus and compare each device with the given
> device, returning a match, or not. As it stands, bus_for_each_dev returns
> either success (the callback worked for each device on the list), or failure
> (the callback failed for some device on the list), but I don't see a
> mechanism to return which device failed without excessive abuse of the
> void*. For now I've made a private copy of bus_for_each_dev which I've
> mucked with the return the properly matching device, and wonder if this
> couldn't be made more generic somehow.

Yes, those helpers are restrictive, and not very useful to you in that
case. It's easy to make more complex versions, but I fear the resulting


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