/* * AMD Elan SC520 processor Watchdog Timer driver * * Based on acquirewdt.c by Alan Cox, * and sbc60xxwdt.c by Jakob Oestergaard * * 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 authors do NOT admit liability nor provide warranty for * any of this software. This material is provided "AS-IS" in * the hope that it may be useful for others. * * (c) Copyright 2001 Scott Jennings * 9/27 - 2001 [Initial release] * * Additional fixes Alan Cox * - Fixed formatting * - Removed debug printks * - Fixed SMP built kernel deadlock * - Switched to private locks not lock_kernel * - Used ioremap/writew/readw * - Added NOWAYOUT support * 4/12 - 2002 Changes by Rob Radez * - Change comments * - Eliminate fop_llseek * - Change CONFIG_WATCHDOG_NOWAYOUT semantics * - Add KERN_* tags to printks * - fix possible wdt_is_open race * - Report proper capabilities in watchdog_info * - Add WDIOC_{GETSTATUS, GETBOOTSTATUS, SETTIMEOUT, * GETTIMEOUT, SETOPTIONS} ioctls * 09/8 - 2003 Changes by Wim Van Sebroeck * - cleanup of trailing spaces * - added extra printk's for startup problems * - use module_param * - made timeout (the emulated heartbeat) a module_param * - made the keepalive ping an internal subroutine * 3/27 - 2004 Changes by Sean Young * - set MMCR_BASE to 0xfffef000 * - CBAR does not need to be read * - removed debugging printks * * This WDT driver is different from most other Linux WDT * drivers in that the driver will ping the watchdog by itself, * because this particular WDT has a very short timeout (1.6 * seconds) and it would be insane to count on any userspace * daemon always getting scheduled within that time frame. * * This driver uses memory mapped IO, and spinlock. */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * The AMD Elan SC520 timeout value is 492us times a power of 2 (0-7) * * 0: 492us 2: 1.01s 4: 4.03s 6: 16.22s * 1: 503ms 3: 2.01s 5: 8.05s 7: 32.21s * * We will program the SC520 watchdog for a timeout of 2.01s. * If we reset the watchdog every ~250ms we should be safe. */ #define WDT_INTERVAL (HZ/4+1) /* * We must not require too good response from the userspace daemon. * Here we require the userspace daemon to send us a heartbeat * char to /dev/watchdog every 30 seconds. */ #define WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */ /* in seconds, will be multiplied by HZ to get seconds to wait for a ping */ static int timeout = WATCHDOG_TIMEOUT; module_param(timeout, int, 0); MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (1 <= timeout <= 3600, default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")"); 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) ")"); /* * AMD Elan SC520 - Watchdog Timer Registers */ #define MMCR_BASE 0xfffef000 /* The default base address */ #define OFFS_WDTMRCTL 0xCB0 /* Watchdog Timer Control Register */ /* WDT Control Register bit definitions */ #define WDT_EXP_SEL_01 0x0001 /* [01] Time-out = 496 us (with 33 Mhz clk). */ #define WDT_EXP_SEL_02 0x0002 /* [02] Time-out = 508 ms (with 33 Mhz clk). */ #define WDT_EXP_SEL_03 0x0004 /* [03] Time-out = 1.02 s (with 33 Mhz clk). */ #define WDT_EXP_SEL_04 0x0008 /* [04] Time-out = 2.03 s (with 33 Mhz clk). */ #define WDT_EXP_SEL_05 0x0010 /* [05] Time-out = 4.07 s (with 33 Mhz clk). */ #define WDT_EXP_SEL_06 0x0020 /* [06] Time-out = 8.13 s (with 33 Mhz clk). */ #define WDT_EXP_SEL_07 0x0040 /* [07] Time-out = 16.27s (with 33 Mhz clk). */ #define WDT_EXP_SEL_08 0x0080 /* [08] Time-out = 32.54s (with 33 Mhz clk). */ #define WDT_IRQ_FLG 0x1000 /* [12] Interrupt Request Flag */ #define WDT_WRST_ENB 0x4000 /* [14] Watchdog Timer Reset Enable */ #define WDT_ENB 0x8000 /* [15] Watchdog Timer Enable */ static __u16 __iomem *wdtmrctl; static void wdt_timer_ping(unsigned long); static DEFINE_TIMER(timer, wdt_timer_ping, 0, 0); static unsigned long next_heartbeat; static unsigned long wdt_is_open; static char wdt_expect_close; static DEFINE_SPINLOCK(wdt_spinlock); /* * Whack the dog */ static void wdt_timer_ping(unsigned long data) { /* If we got a heartbeat pulse within the WDT_US_INTERVAL * we agree to ping the WDT */ if (time_before(jiffies, next_heartbeat)) { /* Ping the WDT */ spin_lock(&wdt_spinlock); writew(0xAAAA, wdtmrctl); writew(0x5555, wdtmrctl); spin_unlock(&wdt_spinlock); /* Re-set the timer interval */ mod_timer(&timer, jiffies + WDT_INTERVAL); } else pr_warn("Heartbeat lost! Will not ping the watchdog\n"); } /* * Utility routines */ static void wdt_config(int writeval) { unsigned long flags; /* buy some time (ping) */ spin_lock_irqsave(&wdt_spinlock, flags); readw(