[v6,2/2] usb/gadget: Add driver for Aspeed SoC virtual hub

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

On Fri, 2018-03-23 at 09:54 +0200, Felipe Balbi wrote:
> Hi,
> 
> Benjamin Herrenschmidt <benh@kernel.crashing.org> writes:
> 
> > The Aspeed BMC SoCs support a "virtual hub" function. It provides some
> > HW support for a top-level USB2 hub behind which sit 5 gadget "ports".
> > 
> > This driver adds support for the full functionality, emulating the
> > hub standard requests and exposing 5 UDC gadget drivers corresponding
> > to the ports.
> > 
> > The hub itself has HW provided dedicated EP0 and EP1 (the latter for
> > hub interrupts). It also has dedicated EP0s for each function. For
> > other endpoints, there's a pool of 15 "generic" endpoints that are
> > shared among the ports.
> > 
> > The driver relies on my previous patch adding a "dispose" EP op to
> > handle EP allocation between ports. EPs are allocated from the shared
> > pool in the UDC "match_ep" callback and assigned to the UDC instance
> > (added to the gadget ep_list).
> > 
> > When the composite driver gets unbound, the new hook will allow the UDC
> > to clean things up and return those EPs to the shared pool.
> > 
> > Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> > ---
> 
> doesn't compile:
> 
> In file included from ./include/linux/bitmap.h:9:0,
>                  from ./include/linux/cpumask.h:12,
>                  from ./arch/x86/include/asm/cpumask.h:5,
>                  from ./arch/x86/include/asm/msr.h:11,
>                  from ./arch/x86/include/asm/processor.h:21,
>                  from ./arch/x86/include/asm/cpufeature.h:5,
>                  from ./arch/x86/include/asm/thread_info.h:53,
>                  from ./include/linux/thread_info.h:38,
>                  from ./arch/x86/include/asm/preempt.h:7,
>                  from ./include/linux/preempt.h:81,
>                  from ./include/linux/spinlock.h:51,
>                  from ./include/linux/seqlock.h:36,
>                  from ./include/linux/time.h:6,
>                  from ./include/linux/stat.h:19,
>                  from ./include/linux/module.h:10,
>                  from drivers/usb/gadget/udc/aspeed-vhub/hub.c:16:
> In function ‘memcpy’,
>     inlined from ‘ast_vhub_rep_desc’ at drivers/usb/gadget/udc/aspeed-vhub/hub.c:276:2:
> ./include/linux/string.h:341:4: error: call to ‘__read_overflow2’ declared with attribute error: detected read beyond size of object passed as 2nd parameter
>     __read_overflow2();

That's really odd... some new gcc thing ? I don't understand where the
overflow would occur... Do you see anything ? Unless my brain is acting
up, there is no overflow and gcc is bogus:

I just hand counted the size of the 3 possible structures "desc" can
point to and compared to the constants used for the size, and it all
fits.

Unfortunately, I can't seem to reproduce with the version of cross
compiler I'm using here, so I'm not sure what construct to use to
make gcc stop erroneously barfing...

Cheers,
Ben.

>     ^~~~~~~~~~~~~~~~~~
> make[4]: *** [scripts/Makefile.build:316: drivers/usb/gadget/udc/aspeed-vhub/hub.o] Error 1
> make[4]: *** Waiting for unfinished jobs....
> make[3]: *** [scripts/Makefile.build:575: drivers/usb/gadget/udc/aspeed-vhub] Error 2
> make[3]: *** Waiting for unfinished jobs....
> make[2]: *** [scripts/Makefile.build:575: drivers/usb/gadget/udc] Error 2
> make[1]: *** [scripts/Makefile.build:575: drivers/usb/gadget] Error 2
> make: *** [Makefile:1722: drivers/usb/] Error 2
> 
>
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