> It's less ugly than it used to be, esp. with the bus_read_X() stuff. There's
> no separate bus_alloc_resource/bus_setup_intr for interrupts though for
> example, just bus_setup_intr() equivalent. This is pretty simple though:
>
> /* OS X */
> IOMemoryMap *myBarMap;
> void *myBar;
> u_int32_t reg;
>
> /* BAR 0 */
> myBarMap =
> provider->mapDeviceMemoryWithRegister(kIOPCIConfigBaseAddress0);
> myBar = myBarMap->getVirtualAddress();
>
> reg = OSReadLittleInt32(myBar, FOO_REG);
> reg |= BAR_FLAG;
> OSWriteLittleIntew(myBar, FOO_REG, reg);
>
> myBar->release();
>
> In FreeBSD-7 this is something like:
>
> struct resource *res;
> int rid;
> u_int32_t reg;
uint32_t is the standards compliant spelling :-)
> rid = PCIR_BAR(0);
> res = bus_alloc_resource_any(dev, SYS_RES_MEMORY, &rid, RF_ACTIVE);
The above should be shortenable to:
res = bus_alloc_resource_any(dev, SYS_RES_MEMORY, PCIR_BAR(0),
RF_ACTIVE);
because we don't need to have rid be a pointer.
> /* XXX: Not sure about endian.. stream_read maybe? */
no. bus_read is correct, because the pci bus is little endian by
definition. bus_stream_read will read/write from native endian to bus
endian.
> reg = bus_read_4(res, FOO_REG);
> reg |= BAR_FLAG;
> bus_write_4(res, FOO_REG, reg);
>
> bus_release_resource(dev, SYS_RES_MEMORY, rid, res);
We should be able to shorten that to:
bus_release_resource(dev, res);
these days.
> Which is very similar though there is some clutter (bus_release_resource()
> should take fewer args, like just dev and res, and it would be nice to say
> something like map_bar(dev, PCIR_BAR(0)) and get back a resource *).
Agreed. If you have mutliple resources, you can stack them up as well.
> Usually drivers come up with macros to hide the bus handles and tags which is
> an indication that they were quite unsightly (thankfully that's been fixed in
> 7). :)
I usually do:
#define RD4(sc, r) bus_read_4(sc->res, (r))
#define WR4(sc, r, v) bus_write_4(sc->res, (r), (v))
which makes usage even shorter. It also helps me hid cross-version
differences...
> Anyways, if you took FreeBSD-7 and cut down some of the gunk similar to OS X
> you'd have something like:
>
> struct resource *res;
> u_int32_t reg;
>
> res = pci_alloc_bar(dev, PCIR_BAR(0));
>
> /* XXX: endian question again */
> reg = bus_read_4(res, FOO_REG);
> reg |= BAR_FLAG;
> bus_write_4(res, FOO_REG, reg);
>
> bus_release_resource(dev, res);
>
> Which is at least somewhat better I think.
In the case where you don't care what kind of mapping you get, that
would work great.
It wouldn't be too hard to implement a pci_alloc_bar that does the
default allocation and mapping. Changing some of the other APIs would
be more difficult...
> > Also, in FreeBSD, the resources are already allocated by the bus
> > code. It just changes ownership to the child when the request comes
> > in...
>
> Yes, this has been a recent improvement.
Yes. We also do it in a lazy way so that if the resource is allocated
or not is transparent to the driver and the system. If it could be
decoded, we reserve it.
Warner
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