devbios problems - OpenBIOS

20 Dec 2002


      Hello,
last week a had time to run devbios on my sis735 based motherboard but there 
are some questions/problems:
In sis_activate it seems that address 0x51 of the virtual kernel address 
space is accessed.
// sis_activate():
  ..
  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 */
static void sis_activate(void)
{
    char b;
    hostbridge = pci_find_class(PCI_CLASS_BRIDGE_HOST<<8,NULL);
    if (!hostbridge)
    	return;
pci_dummy[0]=pci_read(hostbridge, 0x76);
-->	pci_dummy[1]=readb(0x51);
    pci_dummy[2]=pci_read(CURRENT, 0x40);
    pci_dummy[3]=pci_read(CURRENT, 0x45);
/* disable shadow */
    pci_write(hostbridge, 0x76, 0x00);
    /* disable cache */
-->	writeb(pci_dummy[1] & 0x7f, 0x51);
/* Enable 0xFFF8000~0xFFFF0000 decoding on SiS 540/630 */
    pci_write(CURRENT, 0x40, pci_dummy[2]|0x0b);
    /* Flash write enable on SiS 540/630 */
    pci_write(CURRENT, 0x45, pci_dummy[3]|0x40);
/* The same thing on SiS 950 SuperIO side */
    outb(0x87, 0x2e);
    outb(0x01, 0x2e);
    outb(0x55, 0x2e);
    outb(0x55, 0x2e);
    if (inb(0x2f) != 0x87) {
    	/* printf("Can not access SiS 950\n"); */
    	return;
    }
outb(0x24, 0x2e);
    b = inb(0x2f) | 0xfc;
    outb(0x24, 0x2e);
    outb(b, 0x2f);
    outb(0x02, 0x2e);
    outb(0x02, 0x2f);
}
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.
Then there is another problem. (Since the ?? cache disable code ?? (see above)
was commented out I switched off all cache options in BIOS setup: BIOS ROM 
cachable, L1 + L2 Cache of processor.)
When loading the devbios module the flashrom is detected correct and I can 
read it with dd if=/dev/bios | hex|less.
I also can write to the flash with dd if=/dev/zero of=/dev/bios bs=128 
count=1. After this write access the flashrom
can be read with dd to verify that the data is written properly.
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).
I tried this with the EON29F002NT-flashrom which belongs to the board, but 
did not write on that, and the ATMEL.
Since both flashroms are not detected this cannot be a flashrom problem.
I modified bios_write-function to use flash_ready_toggle() instead of 
flash_ready_poll()
and printk timeout variable (the number of toggles+1)
to see if the flash accepted my write commands.
After rebooting an loading the bios.o module I did a
dd if=/dev/zero of=/dev/bios bs=1024 count=1
for the first 128k sector flash_ready_toggle reported timeout=ca. 4000
for all other sectors flash_ready_toggle reported timeout=1 (0 toggles).
This means that the first sector write succeeds, but all following fail.
I don't understand this becaus in the programming loop of bios_write no 
strange things are done:
while (size>0) {
        // atmel-specific code commented out - reasons described above:
        //if ((flashchips[fn].flags & f_manuf_compl) != f_atmel_compl) {
        flash_program();
        //} else {
        //  flash_program_atmel();
        //}
        for (i=0;i<flashchips[fn].pagesize;i++) {
          flash_writeb(offset+writeoffs+i,clipboard[writeoffs+i]);
        }
        if ((flashchips[fn].flags & f_manuf_compl) == f_atmel_compl) {
          udelay(750);
        } else {
    	    if (flashchips[fn].pagesize==1)
    		    udelay(30);
     	    else
          		    udelay(300);
        }
if (flash_ready_poll(offset+writeoffs+flashchips[fn].pagesize-1,
    			 clipboard[writeoffs+flashchips[fn].pagesize-1])) {
          printk (KERN_ERR "BIOS: Error occured, please repeat write 
operation.\n");
        }
        flash_command(0xf0);
writeoffs += flashchips[fn].pagesize;
        size	  -= flashchips[fn].pagesize;
}
I hope that someone can help me to fix the problems.
Regards,
   Peter Kögel
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