254 lines
6.5 KiB
C
254 lines
6.5 KiB
C
/*
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* Watchdog driver for Atmel AT91SAM9x processors.
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*
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* Copyright (C) 2008 Renaud CERRATO r.cerrato@til-technologies.fr
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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/*
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* The Watchdog Timer Mode Register can be only written to once. If the
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* timeout need to be set from Linux, be sure that the bootstrap or the
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* bootloader doesn't write to this register.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/errno.h>
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#include <linux/init.h>
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#include <linux/io.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/platform_device.h>
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#include <linux/types.h>
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#include <linux/watchdog.h>
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#include <linux/jiffies.h>
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#include <linux/timer.h>
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#include <linux/bitops.h>
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#include <linux/uaccess.h>
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#include <linux/of.h>
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#include "at91sam9_wdt.h"
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#define DRV_NAME "AT91SAM9 Watchdog"
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#define wdt_read(field) \
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__raw_readl(at91wdt_private.base + field)
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#define wdt_write(field, val) \
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__raw_writel((val), at91wdt_private.base + field)
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/* AT91SAM9 watchdog runs a 12bit counter @ 256Hz,
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* use this to convert a watchdog
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* value from/to milliseconds.
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*/
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#define ms_to_ticks(t) (((t << 8) / 1000) - 1)
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#define ticks_to_ms(t) (((t + 1) * 1000) >> 8)
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/* Hardware timeout in seconds */
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#define WDT_HW_TIMEOUT 2
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/* Timer heartbeat (500ms) */
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#define WDT_TIMEOUT (HZ/2)
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/* User land timeout */
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#define WDT_HEARTBEAT 15
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static int heartbeat;
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module_param(heartbeat, int, 0);
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MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. "
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"(default = " __MODULE_STRING(WDT_HEARTBEAT) ")");
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static bool nowayout = WATCHDOG_NOWAYOUT;
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module_param(nowayout, bool, 0);
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MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
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"(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
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static struct watchdog_device at91_wdt_dev;
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static void at91_ping(unsigned long data);
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static struct {
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void __iomem *base;
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unsigned long next_heartbeat; /* the next_heartbeat for the timer */
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struct timer_list timer; /* The timer that pings the watchdog */
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} at91wdt_private;
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/* ......................................................................... */
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/*
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* Reload the watchdog timer. (ie, pat the watchdog)
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*/
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static inline void at91_wdt_reset(void)
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{
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wdt_write(AT91_WDT_CR, AT91_WDT_KEY | AT91_WDT_WDRSTT);
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}
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/*
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* Timer tick
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*/
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static void at91_ping(unsigned long data)
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{
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if (time_before(jiffies, at91wdt_private.next_heartbeat) ||
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(!watchdog_active(&at91_wdt_dev))) {
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at91_wdt_reset();
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mod_timer(&at91wdt_private.timer, jiffies + WDT_TIMEOUT);
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} else
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pr_crit("I will reset your machine !\n");
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}
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static int at91_wdt_ping(struct watchdog_device *wdd)
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{
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/* calculate when the next userspace timeout will be */
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at91wdt_private.next_heartbeat = jiffies + wdd->timeout * HZ;
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return 0;
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}
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static int at91_wdt_start(struct watchdog_device *wdd)
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{
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/* calculate the next userspace timeout and modify the timer */
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at91_wdt_ping(wdd);
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mod_timer(&at91wdt_private.timer, jiffies + WDT_TIMEOUT);
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return 0;
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}
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static int at91_wdt_stop(struct watchdog_device *wdd)
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{
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/* The watchdog timer hardware can not be stopped... */
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return 0;
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}
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static int at91_wdt_set_timeout(struct watchdog_device *wdd, unsigned int new_timeout)
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{
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wdd->timeout = new_timeout;
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return 0;
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}
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/*
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* Set the watchdog time interval in 1/256Hz (write-once)
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* Counter is 12 bit.
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*/
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static int at91_wdt_settimeout(unsigned int timeout)
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{
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unsigned int reg;
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unsigned int mr;
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/* Check if disabled */
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mr = wdt_read(AT91_WDT_MR);
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if (mr & AT91_WDT_WDDIS) {
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pr_err("sorry, watchdog is disabled\n");
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return -EIO;
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}
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/*
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* All counting occurs at SLOW_CLOCK / 128 = 256 Hz
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*
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* Since WDV is a 12-bit counter, the maximum period is
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* 4096 / 256 = 16 seconds.
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*/
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reg = AT91_WDT_WDRSTEN /* causes watchdog reset */
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/* | AT91_WDT_WDRPROC causes processor reset only */
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| AT91_WDT_WDDBGHLT /* disabled in debug mode */
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| AT91_WDT_WDD /* restart at any time */
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| (timeout & AT91_WDT_WDV); /* timer value */
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wdt_write(AT91_WDT_MR, reg);
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return 0;
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}
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/* ......................................................................... */
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static const struct watchdog_info at91_wdt_info = {
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.identity = DRV_NAME,
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.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
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WDIOF_MAGICCLOSE,
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};
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static const struct watchdog_ops at91_wdt_ops = {
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.owner = THIS_MODULE,
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.start = at91_wdt_start,
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.stop = at91_wdt_stop,
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.ping = at91_wdt_ping,
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.set_timeout = at91_wdt_set_timeout,
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};
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static struct watchdog_device at91_wdt_dev = {
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.info = &at91_wdt_info,
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.ops = &at91_wdt_ops,
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.timeout = WDT_HEARTBEAT,
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.min_timeout = 1,
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.max_timeout = 0xFFFF,
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};
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static int __init at91wdt_probe(struct platform_device *pdev)
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{
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struct resource *r;
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int res;
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r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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if (!r)
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return -ENODEV;
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at91wdt_private.base = ioremap(r->start, resource_size(r));
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if (!at91wdt_private.base) {
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dev_err(&pdev->dev, "failed to map registers, aborting.\n");
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return -ENOMEM;
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}
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at91_wdt_dev.parent = &pdev->dev;
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watchdog_init_timeout(&at91_wdt_dev, heartbeat, &pdev->dev);
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watchdog_set_nowayout(&at91_wdt_dev, nowayout);
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/* Set watchdog */
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res = at91_wdt_settimeout(ms_to_ticks(WDT_HW_TIMEOUT * 1000));
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if (res)
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return res;
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res = watchdog_register_device(&at91_wdt_dev);
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if (res)
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return res;
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at91wdt_private.next_heartbeat = jiffies + at91_wdt_dev.timeout * HZ;
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setup_timer(&at91wdt_private.timer, at91_ping, 0);
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mod_timer(&at91wdt_private.timer, jiffies + WDT_TIMEOUT);
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pr_info("enabled (heartbeat=%d sec, nowayout=%d)\n",
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at91_wdt_dev.timeout, nowayout);
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return 0;
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}
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static int __exit at91wdt_remove(struct platform_device *pdev)
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{
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watchdog_unregister_device(&at91_wdt_dev);
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pr_warn("I quit now, hardware will probably reboot!\n");
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del_timer(&at91wdt_private.timer);
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return 0;
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}
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#if defined(CONFIG_OF)
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static const struct of_device_id at91_wdt_dt_ids[] = {
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{ .compatible = "atmel,at91sam9260-wdt" },
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{ /* sentinel */ }
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};
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MODULE_DEVICE_TABLE(of, at91_wdt_dt_ids);
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#endif
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static struct platform_driver at91wdt_driver = {
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.remove = __exit_p(at91wdt_remove),
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.driver = {
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.name = "at91_wdt",
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.owner = THIS_MODULE,
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.of_match_table = of_match_ptr(at91_wdt_dt_ids),
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},
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};
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module_platform_driver_probe(at91wdt_driver, at91wdt_probe);
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MODULE_AUTHOR("Renaud CERRATO <r.cerrato@til-technologies.fr>");
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MODULE_DESCRIPTION("Watchdog driver for Atmel AT91SAM9x processors");
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MODULE_LICENSE("GPL");
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