diff options
Diffstat (limited to 'u-boot/drivers/watchdog/at91sam9_wdt.c')
| -rw-r--r-- | u-boot/drivers/watchdog/at91sam9_wdt.c | 80 |
1 files changed, 80 insertions, 0 deletions
diff --git a/u-boot/drivers/watchdog/at91sam9_wdt.c b/u-boot/drivers/watchdog/at91sam9_wdt.c new file mode 100644 index 0000000..25afae7 --- /dev/null +++ b/u-boot/drivers/watchdog/at91sam9_wdt.c @@ -0,0 +1,80 @@ +/* + * [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 *) AT91_WDT_BASE; + + /* 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 *) AT91_WDT_BASE; + 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)); +} |