105 lines
3.1 KiB
ArmAsm
105 lines
3.1 KiB
ArmAsm
/* wdog.s - watchdog initialization for fsl_frdm_k64f BSP */
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/*
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* Copyright (c) 2014 Wind River Systems, Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1) Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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*
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* 2) Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* 3) Neither the name of Wind River Systems nor the names of its contributors
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* may be used to endorse or promote products derived from this software without
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* specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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DESCRIPTION
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This module initializes the watchdog for the fsl_frdm_k64f BSP.
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*/
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#define _ASMLANGUAGE
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#include <board.h>
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#include <toolchain.h>
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#include <sections.h>
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_ASM_FILE_PROLOGUE
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GTEXT(_WdogInit)
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/* watchdog register offsets */
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#define WDOG_SCTRL_HI_OFFSET 0x0
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#define WDOG_UNLOCK_OFFSET 0xE
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/* watchdog command words */
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#define WDOG_UNLOCK_1_CMD 0xC520
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#define WDOG_UNLOCK_2_CMD 0xD928
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/*******************************************************************************
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*
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* _WdogInit - Watchdog timer disable routine
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*
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* This routine will disable the watchdog timer.
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*
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* RETURNS: N/A
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*/
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SECTION_FUNC(TEXT,_WdogInit)
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/*
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* NOTE: DO NOT SINGLE STEP THROUGH THIS FUNCTION!!!
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* There are timing requirements for the execution of the unlock process.
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* Single stepping through the code will cause the CPU to reset.
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*/
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/*
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* First unlock the watchdog so that we can write to registers.
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*
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* This sequence must execute within 20 clock cycles, so disable
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* interrupts to keep the code atomic and ensure the timing.
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*/
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cpsid i
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ldr r0, =PERIPH_ADDR_BASE_WDOG
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movw r1, #WDOG_UNLOCK_1_CMD
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strh r1, [r0, #WDOG_UNLOCK_OFFSET]
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movw r1, #WDOG_UNLOCK_2_CMD
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strh r1, [r0, #WDOG_UNLOCK_OFFSET]
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/*
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* Disable the watchdog.
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*
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* Writes to control/configuration registers must execute within
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* 256 clock cycles after unlocking.
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*/
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ldrh r1, [r0, #WDOG_SCTRL_HI_OFFSET]
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mov r2, #1
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bics r1, r2
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strh r1, [r0, #WDOG_SCTRL_HI_OFFSET]
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cpsie i
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bx lr
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