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

Arnd Bergmann
2010-09-24T17:40:25Z

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.

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

Arnd