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/*
* [origin: Linux kernel drivers/watchdog/at91sam9_wdt.c]
*
* Watchdog driver for Atmel AT91SAM9x processors.
*
* Copyright (C) 2008 Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
* Copyright (C) 2008 Renaud CERRATO r.cerrato@til-technologies.fr
*
* 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.
*/
/*
* The Watchdog Timer Mode Register can be only written to once. If the
* timeout need to be set from U-Boot, be sure that the bootstrap doesn't
* write to this register. Inform Linux to it too
*/
#include <common.h>
#include <watchdog.h>
#include <asm/arch/hardware.h>
#include <asm/arch/io.h>
#include <asm/arch/at91_wdt.h>
/*
* AT91SAM9 watchdog runs a 12bit counter @ 256Hz,
* use this to convert a watchdog
* value from/to milliseconds.
*/
#define ms_to_ticks(t) (((t << 8) / 1000) - 1)
#define ticks_to_ms(t) (((t + 1) * 1000) >> 8)
/* Hardware timeout in seconds */
#define WDT_HW_TIMEOUT 2
/*
* Set the watchdog time interval in 1/256Hz (write-once)
* Counter is 12 bit.
*/
static int at91_wdt_settimeout(unsigned int timeout)
{
unsigned int reg;
at91_wdt_t *wd = (at91_wdt_t *) ATMEL_BASE_WDT;
/* Check if disabled */
if (readl(&wd->mr) & AT91_WDT_MR_WDDIS) {
printf("sorry, watchdog is disabled\n");
return -1;
}
/*
* All counting occurs at SLOW_CLOCK / 128 = 256 Hz
*
* Since WDV is a 12-bit counter, the maximum period is
* 4096 / 256 = 16 seconds.
*/
reg = AT91_WDT_MR_WDRSTEN /* causes watchdog reset */
| AT91_WDT_MR_WDDBGHLT /* disabled in debug mode */
| AT91_WDT_MR_WDD(0xfff) /* restart at any time */
| AT91_WDT_MR_WDV(timeout); /* timer value */
writel(reg, &wd->mr);
return 0;
}
void hw_watchdog_reset(void)
{
at91_wdt_t *wd = (at91_wdt_t *) ATMEL_BASE_WDT;
writel(AT91_WDT_CR_WDRSTT | AT91_WDT_CR_KEY, &wd->cr);
}
void hw_watchdog_init(void)
{
/* 16 seconds timer, resets enabled */
at91_wdt_settimeout(ms_to_ticks(WDT_HW_TIMEOUT * 1000));
}
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