On Thu, Jun 09, 2016 at 10:41:02PM +0200, Alexander Gordeev wrote:
> On Wed, Jun 08, 2016 at 01:59:59PM +0200, Andrew Jones wrote:
> > > > So you need 5 functions
> > > >
> > > > uint32_t get_mask(int bar)
> > > > {
> > > > ...
> > > > }
> > > >
> > > > uint32_t read_dance(int bar)
> > > > {
> > > > read-write1s-dance
> > > > return readl
> > > > }
> > > >
> > > > uint32_t get_size32(int bar)
> > > > {
> > > > uint32_t size = read_dance(bar) & get_mask(bar);
> > > > return ~size + 1;
> > > > }
> > > >
> > > > uint64_t get_size64(int bar)
> > > > {
> > > > uint64_t size = read_dance(bar) & get_mask(bar);
> > > > uint64_t size_hi = read_dance(bar + 1);
> > > >
> > > > size |= size_hi << 32;
> > > > return ~size + 1;
> > > > }
> > > >
> > > > uint64_t get_size(int bar)
> > > > {
> > > > return bar_size(bar) == BAR64 ? get_size64(bar) : get_size32(bar);
> > > > }
> > >
> > > If the above is a pseudo code or you want me to rework using these
> > > functions?
> >
> > Yes and no. You can do what you like, but pci_bar_size32 should
> > return a size (like my get_size32), not a 2's complement of size,
> > otherwise the name is wrong.
>
> Right. So my pci_bar_size32 is your read_dance. Want to use that name
> or i.e. pci_bar_size_complement?
read-dance was more of joke name, but I am starting to like it :-)
pci_bar_size_complement isn't right, as it returns an unmasked value,
not the real complement.
pci_bar_size_helper()? pci_bar_size_read_dance()?
Whatever you like :-)
>
> > > If not, below is how it could look like.
> > >
> > > Also, looking at your get_size() I noticed a bug in my version :-)
> > > when read_dance() is followed by readl() returns zero - that means no
> > > (more) BAR(s).
> > >
> > > phys_addr_t pci_bar_size(pcidevaddr_t dev, int bar_num)
> > > {
> > > uint32_t size;
> > > uint32_t bar;
> > >
> > > size = pci_bar_size32(dev, bar_num);
> > > if (!size)
> > > return 0;
> >
> > Should callers ever call pci_bar_size on a bar_num that will result
> > in zero, "no more BARs"? If not, then you can assert here. Otherwise
> > will all callers know what zero means, and check for it?
>
> Yes, it is an indication a BAR is implemented in HW. But I misled you :/
> I remember some code stopped on a zero-sized BAR, but I do not recall
> what code it was. There is nothing in specs about stopping and both
> Seabios and Linux just continue probing. So I will update the breaks to
> continues.
>
> > Thanks,
> > drew
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