/* * 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 #include #include #include #include #include #include #include #include #include #include #include #include #include #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; 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, .timeout = WDT_HEARTBEAT, .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.parent = &pdev->dev; watchdog_init_timeout(&at91_wdt_dev, heartbeat, &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", at91_wdt_dev.timeout, 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 "); MODULE_DESCRIPTION("Watchdog driver for Atmel AT91SAM9x processors"); MODULE_LICENSE("GPL");