at91sam9_alt_reset.S 1.1 KB

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  1. /*
  2. * reset AT91SAM9G20 as per errata
  3. *
  4. * (C) BitBox Ltd 2010
  5. *
  6. * unless the SDRAM is cleanly shutdown before we hit the
  7. * reset register it can be left driving the data bus and
  8. * killing the chance of a subsequent boot from NAND
  9. *
  10. * This program is free software; you can redistribute it and/or modify
  11. * it under the terms of the GNU General Public License as published by
  12. * the Free Software Foundation; either version 2 of the License, or
  13. * (at your option) any later version.
  14. */
  15. #include <linux/linkage.h>
  16. #include <mach/hardware.h>
  17. #include <mach/at91_ramc.h>
  18. #include <mach/at91_rstc.h>
  19. .arm
  20. .globl at91sam9_alt_restart
  21. at91sam9_alt_restart: ldr r0, =at91_ramc_base @ preload constants
  22. ldr r0, [r0]
  23. ldr r4, =at91_rstc_base
  24. ldr r1, [r4]
  25. mov r2, #1
  26. mov r3, #AT91_SDRAMC_LPCB_POWER_DOWN
  27. ldr r4, =AT91_RSTC_KEY | AT91_RSTC_PERRST | AT91_RSTC_PROCRST
  28. .balign 32 @ align to cache line
  29. str r2, [r0, #AT91_SDRAMC_TR] @ disable SDRAM access
  30. str r3, [r0, #AT91_SDRAMC_LPR] @ power down SDRAM
  31. str r4, [r1, #AT91_RSTC_CR] @ reset processor
  32. b .