453 lines · c
1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * MachZ ZF-Logic Watchdog Timer driver for Linux4 *5 * The author does NOT admit liability nor provide warranty for6 * any of this software. This material is provided "AS-IS" in7 * the hope that it may be useful for others.8 *9 * Author: Fernando Fuganti <fuganti@conectiva.com.br>10 *11 * Based on sbc60xxwdt.c by Jakob Oestergaard12 *13 * We have two timers (wd#1, wd#2) driven by a 32 KHz clock with the14 * following periods:15 * wd#1 - 2 seconds;16 * wd#2 - 7.2 ms;17 * After the expiration of wd#1, it can generate a NMI, SCI, SMI, or18 * a system RESET and it starts wd#2 that unconditionally will RESET19 * the system when the counter reaches zero.20 *21 * 14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>22 * Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT23 */24 25#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt26 27#include <linux/module.h>28#include <linux/moduleparam.h>29#include <linux/types.h>30#include <linux/timer.h>31#include <linux/jiffies.h>32#include <linux/miscdevice.h>33#include <linux/watchdog.h>34#include <linux/fs.h>35#include <linux/ioport.h>36#include <linux/notifier.h>37#include <linux/reboot.h>38#include <linux/init.h>39#include <linux/io.h>40#include <linux/uaccess.h>41 42 43/* ports */44#define ZF_IOBASE 0x21845#define INDEX 0x21846#define DATA_B 0x21947#define DATA_W 0x21A48#define DATA_D 0x21A49 50/* indexes */ /* size */51#define ZFL_VERSION 0x02 /* 16 */52#define CONTROL 0x10 /* 16 */53#define STATUS 0x12 /* 8 */54#define COUNTER_1 0x0C /* 16 */55#define COUNTER_2 0x0E /* 8 */56#define PULSE_LEN 0x0F /* 8 */57 58/* controls */59#define ENABLE_WD1 0x000160#define ENABLE_WD2 0x000261#define RESET_WD1 0x001062#define RESET_WD2 0x002063#define GEN_SCI 0x010064#define GEN_NMI 0x020065#define GEN_SMI 0x040066#define GEN_RESET 0x080067 68 69/* utilities */70 71#define WD1 072#define WD2 173 74#define zf_writew(port, data) { outb(port, INDEX); outw(data, DATA_W); }75#define zf_writeb(port, data) { outb(port, INDEX); outb(data, DATA_B); }76#define zf_get_ZFL_version() zf_readw(ZFL_VERSION)77 78 79static unsigned short zf_readw(unsigned char port)80{81 outb(port, INDEX);82 return inw(DATA_W);83}84 85 86MODULE_AUTHOR("Fernando Fuganti <fuganti@conectiva.com.br>");87MODULE_DESCRIPTION("MachZ ZF-Logic Watchdog driver");88MODULE_LICENSE("GPL");89 90static bool nowayout = WATCHDOG_NOWAYOUT;91module_param(nowayout, bool, 0);92MODULE_PARM_DESC(nowayout,93 "Watchdog cannot be stopped once started (default="94 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");95 96#define PFX "machzwd"97 98static const struct watchdog_info zf_info = {99 .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,100 .firmware_version = 1,101 .identity = "ZF-Logic watchdog",102};103 104 105/*106 * action refers to action taken when watchdog resets107 * 0 = GEN_RESET108 * 1 = GEN_SMI109 * 2 = GEN_NMI110 * 3 = GEN_SCI111 * defaults to GEN_RESET (0)112 */113static int action;114module_param(action, int, 0);115MODULE_PARM_DESC(action, "after watchdog resets, generate: "116 "0 = RESET(*) 1 = SMI 2 = NMI 3 = SCI");117 118static void zf_ping(struct timer_list *unused);119 120static int zf_action = GEN_RESET;121static unsigned long zf_is_open;122static char zf_expect_close;123static DEFINE_SPINLOCK(zf_port_lock);124static DEFINE_TIMER(zf_timer, zf_ping);125static unsigned long next_heartbeat;126 127 128/* timeout for user land heart beat (10 seconds) */129#define ZF_USER_TIMEO (HZ*10)130 131/* timeout for hardware watchdog (~500ms) */132#define ZF_HW_TIMEO (HZ/2)133 134/* number of ticks on WD#1 (driven by a 32KHz clock, 2s) */135#define ZF_CTIMEOUT 0xffff136 137#ifndef ZF_DEBUG138#define dprintk(format, args...)139#else140#define dprintk(format, args...) \141 pr_debug(":%s:%d: " format, __func__, __LINE__ , ## args)142#endif143 144 145static inline void zf_set_status(unsigned char new)146{147 zf_writeb(STATUS, new);148}149 150 151/* CONTROL register functions */152 153static inline unsigned short zf_get_control(void)154{155 return zf_readw(CONTROL);156}157 158static inline void zf_set_control(unsigned short new)159{160 zf_writew(CONTROL, new);161}162 163 164/* WD#? counter functions */165/*166 * Just set counter value167 */168 169static inline void zf_set_timer(unsigned short new, unsigned char n)170{171 switch (n) {172 case WD1:173 zf_writew(COUNTER_1, new);174 fallthrough;175 case WD2:176 zf_writeb(COUNTER_2, new > 0xff ? 0xff : new);177 fallthrough;178 default:179 return;180 }181}182 183/*184 * stop hardware timer185 */186static void zf_timer_off(void)187{188 unsigned int ctrl_reg = 0;189 unsigned long flags;190 191 /* stop internal ping */192 del_timer_sync(&zf_timer);193 194 spin_lock_irqsave(&zf_port_lock, flags);195 /* stop watchdog timer */196 ctrl_reg = zf_get_control();197 ctrl_reg |= (ENABLE_WD1|ENABLE_WD2); /* disable wd1 and wd2 */198 ctrl_reg &= ~(ENABLE_WD1|ENABLE_WD2);199 zf_set_control(ctrl_reg);200 spin_unlock_irqrestore(&zf_port_lock, flags);201 202 pr_info("Watchdog timer is now disabled\n");203}204 205 206/*207 * start hardware timer208 */209static void zf_timer_on(void)210{211 unsigned int ctrl_reg = 0;212 unsigned long flags;213 214 spin_lock_irqsave(&zf_port_lock, flags);215 216 zf_writeb(PULSE_LEN, 0xff);217 218 zf_set_timer(ZF_CTIMEOUT, WD1);219 220 /* user land ping */221 next_heartbeat = jiffies + ZF_USER_TIMEO;222 223 /* start the timer for internal ping */224 mod_timer(&zf_timer, jiffies + ZF_HW_TIMEO);225 226 /* start watchdog timer */227 ctrl_reg = zf_get_control();228 ctrl_reg |= (ENABLE_WD1|zf_action);229 zf_set_control(ctrl_reg);230 spin_unlock_irqrestore(&zf_port_lock, flags);231 232 pr_info("Watchdog timer is now enabled\n");233}234 235 236static void zf_ping(struct timer_list *unused)237{238 unsigned int ctrl_reg = 0;239 unsigned long flags;240 241 zf_writeb(COUNTER_2, 0xff);242 243 if (time_before(jiffies, next_heartbeat)) {244 dprintk("time_before: %ld\n", next_heartbeat - jiffies);245 /*246 * reset event is activated by transition from 0 to 1 on247 * RESET_WD1 bit and we assume that it is already zero...248 */249 250 spin_lock_irqsave(&zf_port_lock, flags);251 ctrl_reg = zf_get_control();252 ctrl_reg |= RESET_WD1;253 zf_set_control(ctrl_reg);254 255 /* ...and nothing changes until here */256 ctrl_reg &= ~(RESET_WD1);257 zf_set_control(ctrl_reg);258 spin_unlock_irqrestore(&zf_port_lock, flags);259 260 mod_timer(&zf_timer, jiffies + ZF_HW_TIMEO);261 } else262 pr_crit("I will reset your machine\n");263}264 265static ssize_t zf_write(struct file *file, const char __user *buf, size_t count,266 loff_t *ppos)267{268 /* See if we got the magic character */269 if (count) {270 /*271 * no need to check for close confirmation272 * no way to disable watchdog ;)273 */274 if (!nowayout) {275 size_t ofs;276 /*277 * note: just in case someone wrote the magic character278 * five months ago...279 */280 zf_expect_close = 0;281 282 /* now scan */283 for (ofs = 0; ofs != count; ofs++) {284 char c;285 if (get_user(c, buf + ofs))286 return -EFAULT;287 if (c == 'V') {288 zf_expect_close = 42;289 dprintk("zf_expect_close = 42\n");290 }291 }292 }293 294 /*295 * Well, anyhow someone wrote to us,296 * we should return that favour297 */298 next_heartbeat = jiffies + ZF_USER_TIMEO;299 dprintk("user ping at %ld\n", jiffies);300 }301 return count;302}303 304static long zf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)305{306 void __user *argp = (void __user *)arg;307 int __user *p = argp;308 switch (cmd) {309 case WDIOC_GETSUPPORT:310 if (copy_to_user(argp, &zf_info, sizeof(zf_info)))311 return -EFAULT;312 break;313 case WDIOC_GETSTATUS:314 case WDIOC_GETBOOTSTATUS:315 return put_user(0, p);316 case WDIOC_KEEPALIVE:317 zf_ping(NULL);318 break;319 default:320 return -ENOTTY;321 }322 return 0;323}324 325static int zf_open(struct inode *inode, struct file *file)326{327 if (test_and_set_bit(0, &zf_is_open))328 return -EBUSY;329 if (nowayout)330 __module_get(THIS_MODULE);331 zf_timer_on();332 return stream_open(inode, file);333}334 335static int zf_close(struct inode *inode, struct file *file)336{337 if (zf_expect_close == 42)338 zf_timer_off();339 else {340 del_timer(&zf_timer);341 pr_err("device file closed unexpectedly. Will not stop the WDT!\n");342 }343 clear_bit(0, &zf_is_open);344 zf_expect_close = 0;345 return 0;346}347 348/*349 * Notifier for system down350 */351 352static int zf_notify_sys(struct notifier_block *this, unsigned long code,353 void *unused)354{355 if (code == SYS_DOWN || code == SYS_HALT)356 zf_timer_off();357 return NOTIFY_DONE;358}359 360static const struct file_operations zf_fops = {361 .owner = THIS_MODULE,362 .write = zf_write,363 .unlocked_ioctl = zf_ioctl,364 .compat_ioctl = compat_ptr_ioctl,365 .open = zf_open,366 .release = zf_close,367};368 369static struct miscdevice zf_miscdev = {370 .minor = WATCHDOG_MINOR,371 .name = "watchdog",372 .fops = &zf_fops,373};374 375 376/*377 * The device needs to learn about soft shutdowns in order to378 * turn the timebomb registers off.379 */380static struct notifier_block zf_notifier = {381 .notifier_call = zf_notify_sys,382};383 384static void __init zf_show_action(int act)385{386 static const char * const str[] = { "RESET", "SMI", "NMI", "SCI" };387 388 pr_info("Watchdog using action = %s\n", str[act]);389}390 391static int __init zf_init(void)392{393 int ret;394 395 pr_info("MachZ ZF-Logic Watchdog driver initializing\n");396 397 ret = zf_get_ZFL_version();398 if (!ret || ret == 0xffff) {399 pr_warn("no ZF-Logic found\n");400 return -ENODEV;401 }402 403 if (action <= 3 && action >= 0)404 zf_action = zf_action >> action;405 else406 action = 0;407 408 zf_show_action(action);409 410 if (!request_region(ZF_IOBASE, 3, "MachZ ZFL WDT")) {411 pr_err("cannot reserve I/O ports at %d\n", ZF_IOBASE);412 ret = -EBUSY;413 goto no_region;414 }415 416 ret = register_reboot_notifier(&zf_notifier);417 if (ret) {418 pr_err("can't register reboot notifier (err=%d)\n", ret);419 goto no_reboot;420 }421 422 ret = misc_register(&zf_miscdev);423 if (ret) {424 pr_err("can't misc_register on minor=%d\n", WATCHDOG_MINOR);425 goto no_misc;426 }427 428 zf_set_status(0);429 zf_set_control(0);430 431 return 0;432 433no_misc:434 unregister_reboot_notifier(&zf_notifier);435no_reboot:436 release_region(ZF_IOBASE, 3);437no_region:438 return ret;439}440 441 442static void __exit zf_exit(void)443{444 zf_timer_off();445 446 misc_deregister(&zf_miscdev);447 unregister_reboot_notifier(&zf_notifier);448 release_region(ZF_IOBASE, 3);449}450 451module_init(zf_init);452module_exit(zf_exit);453