at91sam9_wdt.c
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// SPDX-License-Identifier: GPL-2.0+
/*
* [origin: Linux kernel drivers/watchdog/at91sam9_wdt.c]
*
* Watchdog driver for AT91SAM9x processors.
*
* Copyright (C) 2008 Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
* Copyright (C) 2008 Renaud CERRATO r.cerrato@til-technologies.fr
*/
/*
* 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 <asm/io.h>
#include <asm/arch/at91_wdt.h>
#include <common.h>
#include <dm.h>
#include <errno.h>
#include <wdt.h>
DECLARE_GLOBAL_DATA_PTR;
/*
* AT91SAM9 watchdog runs a 12bit counter @ 256Hz,
* use this to convert a watchdog
* value from seconds.
*/
#define WDT_SEC2TICKS(s) (((s) << 8) - 1)
/* Hardware timeout in seconds */
#define WDT_MAX_TIMEOUT 16
#define WDT_MIN_TIMEOUT 0
#define WDT_DEFAULT_TIMEOUT 2
struct at91_wdt_priv {
void __iomem *regs;
u32 regval;
u32 timeout;
};
/*
* Set the watchdog time interval in 1/256Hz (write-once)
* Counter is 12 bit.
*/
static int at91_wdt_start(struct udevice *dev, u64 timeout_s, ulong flags)
{
struct at91_wdt_priv *priv = dev_get_priv(dev);
u32 timeout = WDT_SEC2TICKS(timeout_s);
if (timeout_s > WDT_MAX_TIMEOUT || timeout_s < WDT_MIN_TIMEOUT)
timeout = priv->timeout;
/* Check if disabled */
if (readl(priv->regs + AT91_WDT_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.
*/
priv->regval = 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(priv->regval, priv->regs + AT91_WDT_MR);
return 0;
}
static int at91_wdt_stop(struct udevice *dev)
{
struct at91_wdt_priv *priv = dev_get_priv(dev);
/* Disable Watchdog Timer */
priv->regval |= AT91_WDT_MR_WDDIS;
writel(priv->regval, priv->regs + AT91_WDT_MR);
return 0;
}
static int at91_wdt_reset(struct udevice *dev)
{
struct at91_wdt_priv *priv = dev_get_priv(dev);
writel(AT91_WDT_CR_WDRSTT | AT91_WDT_CR_KEY, priv->regs + AT91_WDT_CR);
return 0;
}
static const struct wdt_ops at91_wdt_ops = {
.start = at91_wdt_start,
.stop = at91_wdt_stop,
.reset = at91_wdt_reset,
};
static const struct udevice_id at91_wdt_ids[] = {
{ .compatible = "atmel,at91sam9260-wdt" },
{}
};
static int at91_wdt_probe(struct udevice *dev)
{
struct at91_wdt_priv *priv = dev_get_priv(dev);
priv->regs = dev_remap_addr(dev);
if (!priv->regs)
return -EINVAL;
#ifdef CONFIG_AT91_HW_WDT_TIMEOUT
priv->timeout = dev_read_u32_default(dev, "timeout-sec",
WDT_DEFAULT_TIMEOUT);
debug("%s: timeout %d", __func__, priv->timeout);
#endif
debug("%s: Probing wdt%u\n", __func__, dev->seq);
return 0;
}
U_BOOT_DRIVER(at91_wdt) = {
.name = "at91_wdt",
.id = UCLASS_WDT,
.of_match = at91_wdt_ids,
.priv_auto_alloc_size = sizeof(struct at91_wdt_priv),
.ops = &at91_wdt_ops,
.probe = at91_wdt_probe,
};