Re: [RFC][Patch] IBM Real-Time "SMI Free" mode driver -v4

[Vernon Mauery]

On 24-Sep-2010 07:40 PM, Arnd Bergmann wrote:
> On Friday 24 September 2010 19:09:43 Vernon Mauery wrote:
> > I looked into this and tested it on some hardware, but it doesn't work.
> > After more digging and poking, it looks like the reason is that the port
> > IO address is not within the x86 standard port IO range.
> >
> > I tried something like this:
> >
> >                         addr = ioread32(&rtl_table->cmd_port_address);
> >                         plen = rtl_cmd_width/8;
> >                         if (rtl_cmd_type == RTL_ADDR_TYPE_MMIO)
> >                                 rtl_cmd_addr = ioremap(addr, plen);
> >                         else
> >                                 rtl_cmd_addr = ioport_map(addr, plen);
> >                         RTL_DEBUG("rtl_cmd_addr = %#llx\n", (u64)rtl_cmd_addr);
> >
> > It printed out that rtl_cmd_addr was 0, meaning the ioport_map failed.
> > After more digging, it turns out that on at least one of the machines
> > this code is targeted for, the port IO address (from the first line
> > above) is 0x40000.  Even if this did get mapped, the IO_COND macro would
> > target it for MMIO access instead of PIO access.  So I don't think I can
> > use this method (even though it did make my code a lot nicer to read).
> >
> > Any suggestions?
>
> That seems really strange. I thought the inb/outb instructions could not
> actually operate on addresses above 0x10000 at all, since they take a 16
> bit address operand (DX register). Passing 0x40000 into inb should have the
> same effect as zero AFAICT, which means that your existing code should not
> work either.

No, inb/outb have address as as unsigned long, which would explain why 
0x40000 works with PIO.  When doing inb/outb via the ioread/iowrite 
macros, the port value is the address (minus the offset) masked off to 
PIO_MASK, which is 16 bits on x86.

So it looks like this really not going to work and I will have to go 
back to how it was before.  Would it be tacky to write my own little 
macro?

> For non-x86 architectures, I would recommend defining HAVE_ARCH_PIO_SIZE
> and setting PIO_RESERVED to a higher value.

Unfortunately, this is targeted only for x86 platforms.

--Vernon
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