From: "Markus Klotzbücher" <mk@creamnet•de>
To: "Steven Kaiser" <skaiser.uci@gmail•com>
Cc: linuxppc-embedded@ozlabs•org
Subject: Re: MPC5200b kernel module memory mapping
Date: Thu, 21 Sep 2006 20:10:17 +0200 [thread overview]
Message-ID: <87slilxf92.fsf@creamnet.de> (raw)
In-Reply-To: <000001c6dd12$417d7a50$6e4ec880@volt> (Steven Kaiser's message of "Wed, 20 Sep 2006 17:09:49 -0700")
Hi Steven,
"Steven Kaiser" <skaiser.uci@gmail•com> writes:
> In a kernel module, I am trying to iomemory map or ioport map a range of
> addresses so later I can talk directly to custom external hardware. I have
> tried to follow the advice of Rubini chapter 8. I think I am setting it up
> correctly, but at the precise moment I try to write anything within my
> range, the kernel crashes badly. My board is a Lite5200b, using a 2.4.25
> kernel.
...
> // enable LocalBus Chip Select CS2 to hit on our address range
> *(volatile u32 *)MPC5xxx_MM_IPBI &= ~0x00040000;
> *(volatile u16 *)(MPC5xxx_MM_CS2_START + 2) = MALab_MM_START >> 16;
> *(volatile u16 *)(MPC5xxx_MM_CS2_STOP + 2) = MALab_MM_END >> 16;
> *(volatile u32 *)MPC5xxx_MM_IPBI |= 0x00040000;
>
> // map our physical address into kernal virtual address space
> // do I need this call?
> ioaddr = ioremap(MALab_MM_START,MALab_MM_SIZE);
Yes, you do need this call if you want to access physical addresses.
> return 0;
> }
>
> Later (in a ioctrl routine), I will try and write something to the first
> location in my address range. I tried these three ways:
>
> *(volatile u16 *)MALab_MM_START = 0x5555;
> outw(0x5555,MALab_MM_START);
> outw(0x5555,ioaddr);
>
> Any and all of the these calls crash the kernel so horrendously I have to
> reboot. Sometimes I have to delete and mknod a new /dev entry.
>
> I have tried the io memory map technique instead of the above io port map
> technique, using request_mem_region(), with the same crashing results upon
> any writew() call or direct variants. I tried things without the ioremap()
> call-- I get a segmentation fault in these cases.
>
> The request_region() or request_mem_region() seems to work ok. I can cat
> /proc/iomem or /proc/ioports and see my range in there. I am pretty
This doesn't really tell you anything, it's mere housekeeping.
> sure I am setting up the LocalBus chip select registers ok.
I would guess this is not the case. What kind of device is this?
Regards
Markus
next prev parent reply other threads:[~2006-09-21 18:15 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-09-21 0:09 MPC5200b kernel module memory mapping Steven Kaiser
2006-09-21 8:47 ` sudheer
2006-09-21 18:10 ` Markus Klotzbücher [this message]
2006-09-23 20:46 ` Steven Kaiser
2006-09-23 20:55 ` Steven Kaiser
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