[OpenBIOS] devbios problems

Stefan Reinauer stepan at suse.de
Sat Dec 21 16:42:14 CET 2002

* Peter Kögel <peter.koegel at web.de> [021220 11:40]:
> In sis_activate it seems that address 0x51 of the virtual kernel address 
> space is accessed.
>   pci_dummy[1]=readb(0x51);
>   ..
>   writeb(pci_dummy[1] & 0x7f, 0x51);
>   ..
> // sis deactivate():
>   ..
>   writeb(pci_dummy[1], 0x51);
>   ..
> This leads to an segmantation fault in my case. Can someone explain me what 
> this code should do?
> The comment says: /* disable cache */

It should probably either read from the physical address or rather do an
inb/outb. I don't have the specs available and I cannot recall exactly
where this code comes from.

> The next thing I noticed is that the ATMEL29C010A doesn't like the 
> flash_program_atmel() code.
> When I use the flash_program -code everything is fine.
> void flash_program (void)
> {
> 	flash_command(0xa0);
> }
> void flash_program_atmel (void)
> {
> 	flash_command(0x80);
> 	flash_command(0x20);
> }
> The AT29C010A data sheet says that:
>   the code in flash_program() is used:
>     1. to activate data protection
>     2.  ac "program"-command when data protection is activated
>   the flash_program_atmel() code does switch of the data protection.
> I dont know why the flash_program_atmel() code doesn't work for me since it 
> agrees with the data sheet.

> The problem is that after the write access no more flash commands can be 
> executed. That means that every
> other write to the bios does fail and when I
> rmmod bios
> insmod bios.o
> then the kernel module doesn't detect the flashrom until next reboot (the 
> identification command does not work).

so we probably have to reset to data protection after every write by
calling command 0xa0?

> I tried this with the EON29F002NT-flashrom which belongs to the board, but 
> did not write on that, and the ATMEL.

have you tried CVS or 0.3.2? CVS should support some EON chips.
What does /proc/bios say?

Best regards,
The x86 isn't all that complex - it just doesn't make a lot of
sense.          -- Mike Johnson, Leader of 80x86 Design at AMD
	                          Microprocessor Report (1994)

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