Re: Call for Test and Review: bwn(4) - another Broadcom Wireless driver

On Sat, 13 Mar 2010 16:55:58 -0800
Weongyo Jeong <weongyo.jeong_at_gmail.com> wrote:

> On Sat, Mar 13, 2010 at 11:12:05PM +0200, Alex RAY wrote:
> > On Fri, 12 Mar 2010 15:13:34 -0800
> > Weongyo Jeong <weongyo.jeong_at_gmail.com> wrote:
> > 
> > > 
> > > I thought that your opinion was right and if mem is
> > > 0xf4000000-0xf4003fff (16 Kb) I thought the device has 4 cores.  However
> > > it looks this was wrong according to the below document:
> > > 
> > > 	http://voodoowarez.com/bcm5365p.pdf
> > > 
> > > Please see Section 3: PCI Core, PCI Bus (Page 34) that it indicates that
> > > 16Kb, maybe 8 Kb in the old devices is core register region.
> > > 
> > >   "Accesses to the lower half of the core register region are translated
> > >    into system backplane accesses using the PCIBAR0Window register"
> > >   "Accesses to offsets 0x1000 to 0x17FF of this region initiate a direct
> > >    access to the external SPROM"
> > > 
> > > If we just access memory using offset + core and bus_space_read_x
> > > interfaces it would actually not access core register region.
> > > 
> > > So without solving this problem it looks it could not remove coreswitch
> > > routines.
> > > 
> > > regards,
> > > Weongyo Jeong
> > > 
> > 
> > Hi,
> > 
> > this document about SoC BCM5365P, not about PCI device with PCI to SSB
> > bridge.
> 
> Yes it's about SoC BCM5365P but I think the basic concept of Silicon
> Backplane would be same at a PCI device with PCI to SSB bridge.
> 
> > I know in SoC`s like BSM5365 (I test it in BCM5354 and BCM5836) core
> > switching is not required.
> > 
> > BCM5354 - http://lists.freebsd.org/pipermail/freebsd-mips/2009-June/000421.html
> > BCM5836 - http://lists.freebsd.org/pipermail/freebsd-mips/2010-February/000635.html
> 
> The above URLs you mentioned indicates that
> 
> siba0: <Sonics SiliconBackplane rev 0x0> at mem 0x18000000-0x18006fff on nexus0
> siba_cc0: <ChipCommon core> at mem 0x18000000-0x18000fff irq 0 on siba0
> bfe0: <Broadcom 44xx Ethernet Chip> at mem 0x18001000-0x18001fff irq 1 on siba0
> siba_mips0: <MIPS 3302 processor> at mem 0x18002000-0x18002fff on siba0
> ohci0: <SiBa integrated USB controller> at mem 0x18003000-0x18003fff irq 4 on siba0
> 
> siba0 used memory region at starting 0x18000000 that I think this is a
> reason why it doesn't require core switching and each cores have their
> own memory region at starting 0x1800xxxx.
> 
> But in a case of PCI device with PCI to SSB bridge, it normally used
> 0xf4000000, 0xfe200000 or other address which reserved by parent PCI
> bridge.
> 
> > With PCI device, when device report memory window
> > 0xf4000000-0xf4003fff, why we can`t use full window?
> 
> Because I'm not a Silicon Backplane expert I could not answer this
> question.  But I'd like to make sure that memory window at 0xf4000000
> (size 16 Kbytes) comes from PCI BAR0 when pci(4) attached device.
> Moreover I believe size of memory window also comes from PCI BAR0 size
> testing of pci(4).
> 
> Of course I think we can try to remap full memory window after
> calculating numbers of core but it looks meaning would be little bit
> different.
> 
> > May be You can test your code without core switching?
> 
> I tried to remove core switching code in siba_bwn bridge but after
> moment I got stuck to go forward.  For example,
> 
> I have 1 device which attached with bwn(4) and it has 4 cores:
> 
>   0x18000000-0x18000fff		ChipCommon
>   0x18001000-0x18001fff		EMAC
>   0x18002000-0x18002fff		PCI
>   0x18003000-0x18003fff		PCMCIA
> 
> When it attached at siba_bwn it shows its memory region at 0xfe2fe000 -
> 0xfe2fffff (8 Kbytes).  Initial PCI BAR0 value was 0x18002000.

Yes, You're right. I found another way.
We can use SBtoPCITranslation2 (Offset 0x108) register, in that way we can access to SSB without coreswitching.
(Page 42)

Initial access for copy SPROM and preconfigure make via BAR0, then setup SBtoPCITranslation2 and access to SSB direct. 

> 
> If your opinion is right the memory region for full window should be
> 0xfe2fe000 - 0xfe301fff (16 Kb for 4 core, each core consumes 0x1000
> size)
> 
> Even if I tried to remap memory region from 0xfe2fe000 to 0xfe301fff and
> setting PCI BAR0 to 0x18000000, another problem is occurred for reading
> SPROM data.  To access external SPROM it could be possible to access
> bus_space_read_2(bt, bh, 0x1000 ~ 0x17ff) at ChipCommon core.  But
> accessing register in a core could not over 0xfff because maximum size
> of a core limited within 0x1000.
> 
> That means internally in Silicon Backplane it has a special meaning if
> it try to access over 0x1000 or 0x2000 which mentioned a quote at
> Section 3: PCI Core, PCI Bus (Page 34).
> 
> I guess you're thinking that we could access EMAC core using
> bus_space_read_2(bt, bh, 0x1000 ~ 0x1fff) after setting full memory
> window.  But it looks it's not possible.
> 
> regards,
> Weongyo Jeong


-- 
Alex RAY <ray_at_ddteam.net>