contrib/loaders/watchdog/armv7m_kinetis_wdog.s

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   2
   3 /***************************************************************************
   4  *   Copyright (C) 2015 Tomas Vanek                                        *
   5  *   vanekt@fbl.cz                                                         *
   6  ***************************************************************************/
   7
   8 /*
   9         Disable watchdog for Kinetis Kx and KVx
  10         Parameters:
  11                 r0 ... WDOG base (in)
  12
  13         Used instruction set should work on both Cortex-M4 and M0+
  14 */
  15
  16         .text
  17         .syntax unified
  18         .cpu cortex-m0
  19         .thumb
  20
  21 /* WDOG registers offsets */
  22 WDOG_STCTRLH    = 0
  23 WDOG_UNLOCK     = 0x0e
  24
  25 WDOG_KEY1       = 0xc520
  26 WDOG_KEY2       = 0xd928
  27
  28         .thumb_func
  29 start:
  30 /* WDOG_UNLOCK = 0xC520 */
  31         ldr     r2, =WDOG_KEY1
  32         strh    r2, [r0, WDOG_UNLOCK]
  33 /* WDOG_UNLOCK = 0xD928 */
  34         ldr     r2, =WDOG_KEY2
  35         strh    r2, [r0, WDOG_UNLOCK]
  36 /* WDOG_STCTRLH clear bit 0 */
  37         movs    r4, #1
  38         ldrh    r2, [r0, WDOG_STCTRLH]
  39         bics    r2, r4
  40         strh    r2, [r0, WDOG_STCTRLH]
  41 /* OpenOCD checks exit point address. Jump to the very end. */
  42         b       done
  43
  44         .pool
  45
  46 /* Avoid padding at .text segment end. Otherwise exit point check fails. */
  47         .skip   ( . - start + 2) & 2, 0
  48 done:
  49         bkpt    #0
  50
  51         .end