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/*
* Watchdog driver for Atmel AT91SAM9x processors.
*
* 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 Linux, be sure that the bootstrap or the
* bootloader doesn't write to this register.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/platform_device.h>
#include <linux/types.h>
#include <linux/watchdog.h>
#include <linux/jiffies.h>
#include <linux/timer.h>
#include <linux/bitops.h>
#include <linux/uaccess.h>
#include <linux/of.h>
#include "at91sam9_wdt.h"
#define DRV_NAME "AT91SAM9 Watchdog"
#define wdt_read(field) \
__raw_readl(at91wdt_private.base + field)
#define wdt_write(field, val) \
__raw_writel((val), at91wdt_private.base + field)
/* 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
/* Timer heartbeat (500ms) */
#define WDT_TIMEOUT (HZ/2)
/* User land timeout */
#define WDT_HEARTBEAT 15
static int heartbeat = WDT_HEARTBEAT;
module_param(heartbeat, int, 0);
MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. "
"(default = " __MODULE_STRING(WDT_HEARTBEAT) ")");
static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
"(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
static struct watchdog_device at91_wdt_dev;
static void at91_ping(unsigned long data);
static struct {
void __iomem *base;
unsigned long next_heartbeat; /* the next_heartbeat for the timer */
struct timer_list timer; /* The timer that pings the watchdog */
} at91wdt_private;
/* ......................................................................... */
/*
* Reload the watchdog timer. (ie, pat the watchdog)
*/
static inline void at91_wdt_reset(void)
{
wdt_write(AT91_WDT_CR, AT91_WDT_KEY | AT91_WDT_WDRSTT);
}
/*
* Timer tick
*/
static void at91_ping(unsigned long data)
{
if (time_before(jiffies, at91wdt_private.next_heartbeat) ||
(!watchdog_active(&at91_wdt_dev))) {
at91_wdt_reset();
mod_timer(&at91wdt_private.timer, jiffies + WDT_TIMEOUT);
} else
pr_crit("I will reset your machine !\n");
}
static int at91_wdt_ping(struct watchdog_device *wdd)
{
/* calculate when the next userspace timeout will be */
at91wdt_private.next_heartbeat = jiffies + wdd->timeout * HZ;
return 0;
}
static int at91_wdt_start(struct watchdog_device *wdd)
{
/* calculate the next userspace timeout and modify the timer */
at91_wdt_ping(wdd);
mod_timer(&at91wdt_private.timer, jiffies + WDT_TIMEOUT);
return 0;
}
static int at91_wdt_stop(struct watchdog_device *wdd)
{
/* The watchdog timer hardware can not be stopped... */
return 0;
}
static int at91_wdt_set_timeout(struct watchdog_device *wdd, unsigned int new_timeout)
{
wdd->timeout = new_timeout;
return 0;
}
/*
* 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;
unsigned int mr;
/* Check if disabled */
mr = wdt_read(AT91_WDT_MR);
if (mr & AT91_WDT_WDDIS) {
pr_err("sorry, watchdog is disabled\n");
return -EIO;
}
/*
* 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_WDRSTEN /* causes watchdog reset */
/* | AT91_WDT_WDRPROC causes processor reset only */
| AT91_WDT_WDDBGHLT /* disabled in debug mode */
| AT91_WDT_WDD /* restart at any time */
| (timeout & AT91_WDT_WDV); /* timer value */
wdt_write(AT91_WDT_MR, reg);
return 0;
}
/* ......................................................................... */
static const struct watchdog_info at91_wdt_info = {
.identity = DRV_NAME,
.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
WDIOF_MAGICCLOSE,
};
static const struct watchdog_ops at91_wdt_ops = {
.owner = THIS_MODULE,
.start = at91_wdt_start,
.stop = at91_wdt_stop,
.ping = at91_wdt_ping,
.set_timeout = at91_wdt_set_timeout,
};
static struct watchdog_device at91_wdt_dev = {
.info = &at91_wdt_info,
.ops = &at91_wdt_ops,
.min_timeout = 1,
.max_timeout = 0xFFFF,
};
static int __init at91wdt_probe(struct platform_device *pdev)
{
struct resource *r;
int res;
r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!r)
return -ENODEV;
at91wdt_private.base = ioremap(r->start, resource_size(r));
if (!at91wdt_private.base) {
dev_err(&pdev->dev, "failed to map registers, aborting.\n");
return -ENOMEM;
}
at91_wdt_dev.timeout = heartbeat;
at91_wdt_dev.parent = &pdev->dev;
watchdog_set_nowayout(&at91_wdt_dev, nowayout);
/* Set watchdog */
res = at91_wdt_settimeout(ms_to_ticks(WDT_HW_TIMEOUT * 1000));
if (res)
return res;
res = watchdog_register_device(&at91_wdt_dev);
if (res)
return res;
at91wdt_private.next_heartbeat = jiffies + at91_wdt_dev.timeout * HZ;
setup_timer(&at91wdt_private.timer, at91_ping, 0);
mod_timer(&at91wdt_private.timer, jiffies + WDT_TIMEOUT);
pr_info("enabled (heartbeat=%d sec, nowayout=%d)\n",
heartbeat, nowayout);
return 0;
}
static int __exit at91wdt_remove(struct platform_device *pdev)
{
watchdog_unregister_device(&at91_wdt_dev);
pr_warn("I quit now, hardware will probably reboot!\n");
del_timer(&at91wdt_private.timer);
return 0;
}
#if defined(CONFIG_OF)
static const struct of_device_id at91_wdt_dt_ids[] = {
{ .compatible = "atmel,at91sam9260-wdt" },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, at91_wdt_dt_ids);
#endif
static struct platform_driver at91wdt_driver = {
.remove = __exit_p(at91wdt_remove),
.driver = {
.name = "at91_wdt",
.owner = THIS_MODULE,
.of_match_table = of_match_ptr(at91_wdt_dt_ids),
},
};
module_platform_driver_probe(at91wdt_driver, at91wdt_probe);
MODULE_AUTHOR("Renaud CERRATO <r.cerrato@til-technologies.fr>");
MODULE_DESCRIPTION("Watchdog driver for Atmel AT91SAM9x processors");
MODULE_LICENSE("GPL");
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