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