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/***************************************************************************
* Copyright (C) 2017 Tomas Vanek *
* vanekt@fbl.cz *
* *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 2 of the License, or *
* (at your option) any later version. *
* *
* This program is distributed in the hope that it will be useful, *
* but WITHOUT ANY WARRANTY; without even the implied warranty of *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
* GNU General Public License for more details. *
* *
* You should have received a copy of the GNU General Public License *
* along with this program; if not, write to the *
* Free Software Foundation, Inc. *
***************************************************************************/
/*
Disable watchdog, 32-bit version for newer Kinetis
Parameters:
r0 ... WDOG32 base (in)
Used instruction set should work on both Cortex-M4 and M0+
*/
.text
.syntax unified
.cpu cortex-m0
.thumb
/* WDOG registers offsets */
WDOG_CS = 0
WDOG_CNT = 4
WDOG_TOVAL = 8
WDOG_KEY = 0xd928c520
.thumb_func
start:
/* test WDOG_CS bit CMD32EN */
ldr r2, [r0, WDOG_CS]
ldr r3, =0x2000
tst r2, r3
ldr r3, =WDOG_KEY
beq cmd16
/* WDOG_CNT = key */
str r3, [r0, WDOG_CNT]
b unlocked
cmd16:
/* WDOG_CNT = key, halfword by halfword */
strh r3, [r0, WDOG_CNT]
lsrs r3, r3, #16
strh r3, [r0, WDOG_CNT]
/* WDOG_CS: clear EN bit 7, set UPDATE bit 5 */
unlocked:
movs r4, #0x80
bics r2, r4
movs r4, #0x20
orrs r2, r4
str r2, [r0, WDOG_CS]
/* All active WDOG registers have to be updated, set dummy timeout */
/* WDOG_TOVAL = 0x400 */
ldr r3, =0x400
str r3, [r0, WDOG_TOVAL]
/* OpenOCD checks exit point address. Jump to the very end. */
b done
.pool
/* Avoid padding at .text segment end. Otherwise exit point check fails. */
.skip ( . - start + 2) & 2, 0
done:
bkpt #0
.end
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