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Add a simple ARM SP805 watchdog driver 

Based on SP805 Programmer's model (ARM DDI 0270B). This driver
provides three public APIs:

    void sp805_start(uintptr_t base, unsigned long ticks);
    void sp805_stop(uintptr_t base);
    void sp805_refresh(uintptr_t base, unsigned long ticks);

Upon start, the watchdog starts counting down from the number of
ticks specified. When the count reaches 0 an interrupt is triggered.
The watchdog restarts counting down from the number of ticks
specified. If the count reaches 0 again, the system is reset. A
mechanism to handle the interrupt has not been implemented. Instead,
the API to refresh the watchdog should be used instead to prevent a
system reset.

Change-Id: I799d53f8d1213b10b341a4a67fde6486e89a3dab
This commit is contained in:
Juan Castillo 2014-07-08 17:20:41 +01:00
parent 9784dbda11
commit 3804197383
2 changed files with 132 additions and 0 deletions
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74
drivers/arm/sp805/sp805.c Normal file
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/*
* Copyright (c) 2015, ARM Limited and Contributors. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* Neither the name of ARM nor the names of its contributors may be used
* to endorse or promote products derived from this software without specific
* prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <mmio.h>
#include <sp805.h>
#include <stdint.h>
/* Inline register access functions */
static inline void sp805_write_wdog_load(uintptr_t base, unsigned long value)
{
mmio_write_32(base + SP805_WDOG_LOAD_OFF, value);
}
static inline void sp805_write_wdog_ctrl(uintptr_t base, unsigned long value)
{
mmio_write_32(base + SP805_WDOG_CTR_OFF, value);
}
static inline void sp805_write_wdog_lock(uintptr_t base, unsigned long value)
{
mmio_write_32(base + SP805_WDOG_LOCK_OFF, value);
}
/* Public API implementation */
void sp805_start(uintptr_t base, unsigned long ticks)
{
sp805_write_wdog_load(base, ticks);
sp805_write_wdog_ctrl(base, SP805_CTR_RESEN | SP805_CTR_INTEN);
/* Lock registers access */
sp805_write_wdog_lock(base, 0);
}
void sp805_stop(uintptr_t base)
{
sp805_write_wdog_lock(base, WDOG_UNLOCK_KEY);
sp805_write_wdog_ctrl(base, 0);
}
void sp805_refresh(uintptr_t base, unsigned long ticks)
{
sp805_write_wdog_lock(base, WDOG_UNLOCK_KEY);
sp805_write_wdog_load(base, ticks);
sp805_write_wdog_lock(base, 0);
}

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include/drivers/arm/sp805.h Normal file
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/*
* Copyright (c) 2015, ARM Limited and Contributors. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* Neither the name of ARM nor the names of its contributors may be used
* to endorse or promote products derived from this software without specific
* prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef __SP805_H__
#define __SP805_H__
/* SP805 register offset */
#define SP805_WDOG_LOAD_OFF 0x000
#define SP805_WDOG_CTR_OFF 0x008
#define SP805_WDOG_LOCK_OFF 0xc00
/* Magic word to unlock the wd registers */
#define WDOG_UNLOCK_KEY 0x1ACCE551
/* Register field definitions */
#define SP805_CTR_RESEN (1 << 1)
#define SP805_CTR_INTEN (1 << 0)
#ifndef __ASSEMBLY__
#include <stdint.h>
/* Public high level API */
void sp805_start(uintptr_t base, unsigned long ticks);
void sp805_stop(uintptr_t base);
void sp805_refresh(uintptr_t base, unsigned long ticks);
#endif /* __ASSEMBLY__ */
#endif /* __SP805_H__ */