Execute Reset via CheckStop approach

Wolfgang Denk wd at denx.de
Thu Jul 25 01:46:20 EST 2002

In message <NEBBINFJMPEFJBMDGBGMAEOGFAAA.govindan at india.tejasnetworks.com> you wrote:
> Here is something we found working:
>       addr = 0x10000000;  // This should be a non-accessible memory
> location.

The big disadvantage of this approach is that it works on one  board,
and fails on another - or even on the same board after you added some
more RAM, etc.

We solved this problem in our version (see the  CVS)  by  explicitely
invalidating the mapping in the memory controller:

        /* Get base address mapped by BR0/OR0
        bad_addr = ((immap_t *)IMAP_ADDR)->im_memctl.memc_br0 & 0xFFFF8000;

        /* Enable CheckStop Reset
        ((immap_t *)IMAP_ADDR)->im_clkrst.car_rmr |= 0x00000001;

        /* Invalidate BR0 mapping
        ((immap_t *)IMAP_ADDR)->im_memctl.memc_br0 = 0;

        /* Set MSR and cause reset
        __asm__("mfmsr %0" : "=r" (msr) );
        msr &= ~0x1000;
        __asm__("mtmsr %0" : "=r" (msr) );
        dummy = * (unsigned char *) bad_addr;
        printk("Restart failed\n");

Wolfgang Denk

Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd at denx.de
Microsoft Compatibility:
     your old Windows 3.11 application crash exactly as the new ones.

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