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0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  *  SMsC 37B787 Watchdog Timer driver for Linux 2.6.x.x
0004  *
0005  *  Based on acquirewdt.c by Alan Cox <alan@lxorguk.ukuu.org.uk>
0006  *  and some other existing drivers
0007  *
0008  *  The authors do NOT admit liability nor provide warranty for
0009  *  any of this software. This material is provided "AS-IS" in
0010  *  the hope that it may be useful for others.
0011  *
0012  *  (C) Copyright 2003-2006  Sven Anders <anders@anduras.de>
0013  *
0014  *  History:
0015  *  2003 - Created version 1.0 for Linux 2.4.x.
0016  *  2006 - Ported to Linux 2.6, added nowayout and MAGICCLOSE
0017  *         features. Released version 1.1
0018  *
0019  *  Theory of operation:
0020  *
0021  *  A Watchdog Timer (WDT) is a hardware circuit that can
0022  *  reset the computer system in case of a software fault.
0023  *  You probably knew that already.
0024  *
0025  *  Usually a userspace daemon will notify the kernel WDT driver
0026  *  via the /dev/watchdog special device file that userspace is
0027  *  still alive, at regular intervals.  When such a notification
0028  *  occurs, the driver will usually tell the hardware watchdog
0029  *  that everything is in order, and that the watchdog should wait
0030  *  for yet another little while to reset the system.
0031  *  If userspace fails (RAM error, kernel bug, whatever), the
0032  *  notifications cease to occur, and the hardware watchdog will
0033  *  reset the system (causing a reboot) after the timeout occurs.
0034  *
0035  * Create device with:
0036  *  mknod /dev/watchdog c 10 130
0037  *
0038  * For an example userspace keep-alive daemon, see:
0039  *   Documentation/watchdog/wdt.rst
0040  */
0041 
0042 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
0043 
0044 #include <linux/module.h>
0045 #include <linux/moduleparam.h>
0046 #include <linux/types.h>
0047 #include <linux/miscdevice.h>
0048 #include <linux/watchdog.h>
0049 #include <linux/delay.h>
0050 #include <linux/fs.h>
0051 #include <linux/ioport.h>
0052 #include <linux/notifier.h>
0053 #include <linux/reboot.h>
0054 #include <linux/init.h>
0055 #include <linux/spinlock.h>
0056 #include <linux/io.h>
0057 #include <linux/uaccess.h>
0058 
0059 
0060 /* enable support for minutes as units? */
0061 /* (does not always work correctly, so disabled by default!) */
0062 #define SMSC_SUPPORT_MINUTES
0063 #undef SMSC_SUPPORT_MINUTES
0064 
0065 #define MAX_TIMEOUT     255
0066 
0067 #define UNIT_SECOND     0
0068 #define UNIT_MINUTE     1
0069 
0070 #define VERSION     "1.1"
0071 
0072 #define IOPORT      0x3F0
0073 #define IOPORT_SIZE     2
0074 #define IODEV_NO    8
0075 
0076 static int unit = UNIT_SECOND;  /* timer's unit */
0077 static int timeout = 60;    /* timeout value: default is 60 "units" */
0078 static unsigned long timer_enabled;   /* is the timer enabled? */
0079 
0080 static char expect_close;       /* is the close expected? */
0081 
0082 static DEFINE_SPINLOCK(io_lock);/* to guard the watchdog from io races */
0083 
0084 static bool nowayout = WATCHDOG_NOWAYOUT;
0085 
0086 /* -- Low level function ----------------------------------------*/
0087 
0088 /* unlock the IO chip */
0089 
0090 static inline void open_io_config(void)
0091 {
0092     outb(0x55, IOPORT);
0093     mdelay(1);
0094     outb(0x55, IOPORT);
0095 }
0096 
0097 /* lock the IO chip */
0098 static inline void close_io_config(void)
0099 {
0100     outb(0xAA, IOPORT);
0101 }
0102 
0103 /* select the IO device */
0104 static inline void select_io_device(unsigned char devno)
0105 {
0106     outb(0x07, IOPORT);
0107     outb(devno, IOPORT+1);
0108 }
0109 
0110 /* write to the control register */
0111 static inline void write_io_cr(unsigned char reg, unsigned char data)
0112 {
0113     outb(reg, IOPORT);
0114     outb(data, IOPORT+1);
0115 }
0116 
0117 /* read from the control register */
0118 static inline char read_io_cr(unsigned char reg)
0119 {
0120     outb(reg, IOPORT);
0121     return inb(IOPORT+1);
0122 }
0123 
0124 /* -- Medium level functions ------------------------------------*/
0125 
0126 static inline void gpio_bit12(unsigned char reg)
0127 {
0128     /* -- General Purpose I/O Bit 1.2 --
0129      * Bit 0,   In/Out: 0 = Output, 1 = Input
0130      * Bit 1,   Polarity: 0 = No Invert, 1 = Invert
0131      * Bit 2,   Group Enable Intr.: 0 = Disable, 1 = Enable
0132      * Bit 3/4, Function select: 00 = GPI/O, 01 = WDT, 10 = P17,
0133      *                           11 = Either Edge Triggered Intr. 2
0134      * Bit 5/6  (Reserved)
0135      * Bit 7,   Output Type: 0 = Push Pull Bit, 1 = Open Drain
0136      */
0137     write_io_cr(0xE2, reg);
0138 }
0139 
0140 static inline void gpio_bit13(unsigned char reg)
0141 {
0142     /* -- General Purpose I/O Bit 1.3 --
0143      * Bit 0,  In/Out: 0 = Output, 1 = Input
0144      * Bit 1,  Polarity: 0 = No Invert, 1 = Invert
0145      * Bit 2,  Group Enable Intr.: 0 = Disable, 1 = Enable
0146      * Bit 3,  Function select: 0 = GPI/O, 1 = LED
0147      * Bit 4-6 (Reserved)
0148      * Bit 7,  Output Type: 0 = Push Pull Bit, 1 = Open Drain
0149      */
0150     write_io_cr(0xE3, reg);
0151 }
0152 
0153 static inline void wdt_timer_units(unsigned char new_units)
0154 {
0155     /* -- Watchdog timer units --
0156      * Bit 0-6 (Reserved)
0157      * Bit 7,  WDT Time-out Value Units Select
0158      *         (0 = Minutes, 1 = Seconds)
0159      */
0160     write_io_cr(0xF1, new_units);
0161 }
0162 
0163 static inline void wdt_timeout_value(unsigned char new_timeout)
0164 {
0165     /* -- Watchdog Timer Time-out Value --
0166      * Bit 0-7 Binary coded units (0=Disabled, 1..255)
0167      */
0168     write_io_cr(0xF2, new_timeout);
0169 }
0170 
0171 static inline void wdt_timer_conf(unsigned char conf)
0172 {
0173     /* -- Watchdog timer configuration --
0174      * Bit 0   Joystick enable: 0* = No Reset, 1 = Reset WDT upon
0175      *                          Gameport I/O
0176      * Bit 1   Keyboard enable: 0* = No Reset, 1 = Reset WDT upon KBD Intr.
0177      * Bit 2   Mouse enable: 0* = No Reset, 1 = Reset WDT upon Mouse Intr
0178      * Bit 3   Reset the timer
0179      *         (Wrong in SMsC documentation? Given as: PowerLED Timout
0180      *                          Enabled)
0181      * Bit 4-7 WDT Interrupt Mapping: (0000* = Disabled,
0182      *            0001=IRQ1, 0010=(Invalid), 0011=IRQ3 to 1111=IRQ15)
0183      */
0184     write_io_cr(0xF3, conf);
0185 }
0186 
0187 static inline void wdt_timer_ctrl(unsigned char reg)
0188 {
0189     /* -- Watchdog timer control --
0190      * Bit 0   Status Bit: 0 = Timer counting, 1 = Timeout occurred
0191      * Bit 1   Power LED Toggle: 0 = Disable Toggle, 1 = Toggle at 1 Hz
0192      * Bit 2   Force Timeout: 1 = Forces WD timeout event (self-cleaning)
0193      * Bit 3   P20 Force Timeout enabled:
0194      *          0 = P20 activity does not generate the WD timeout event
0195      *          1 = P20 Allows rising edge of P20, from the keyboard
0196      *              controller, to force the WD timeout event.
0197      * Bit 4   (Reserved)
0198      * -- Soft power management --
0199      * Bit 5   Stop Counter: 1 = Stop software power down counter
0200      *            set via register 0xB8, (self-cleaning)
0201      *            (Upon read: 0 = Counter running, 1 = Counter stopped)
0202      * Bit 6   Restart Counter: 1 = Restart software power down counter
0203      *            set via register 0xB8, (self-cleaning)
0204      * Bit 7   SPOFF: 1 = Force software power down (self-cleaning)
0205      */
0206     write_io_cr(0xF4, reg);
0207 }
0208 
0209 /* -- Higher level functions ------------------------------------*/
0210 
0211 /* initialize watchdog */
0212 
0213 static void wb_smsc_wdt_initialize(void)
0214 {
0215     unsigned char old;
0216 
0217     spin_lock(&io_lock);
0218     open_io_config();
0219     select_io_device(IODEV_NO);
0220 
0221     /* enable the watchdog */
0222     gpio_bit13(0x08);  /* Select pin 80 = LED not GPIO */
0223     gpio_bit12(0x0A);  /* Set pin 79 = WDT not
0224                   GPIO/Output/Polarity=Invert */
0225     /* disable the timeout */
0226     wdt_timeout_value(0);
0227 
0228     /* reset control register */
0229     wdt_timer_ctrl(0x00);
0230 
0231     /* reset configuration register */
0232     wdt_timer_conf(0x00);
0233 
0234     /* read old (timer units) register */
0235     old = read_io_cr(0xF1) & 0x7F;
0236     if (unit == UNIT_SECOND)
0237         old |= 0x80;    /* set to seconds */
0238 
0239     /* set the watchdog timer units */
0240     wdt_timer_units(old);
0241 
0242     close_io_config();
0243     spin_unlock(&io_lock);
0244 }
0245 
0246 /* shutdown the watchdog */
0247 
0248 static void wb_smsc_wdt_shutdown(void)
0249 {
0250     spin_lock(&io_lock);
0251     open_io_config();
0252     select_io_device(IODEV_NO);
0253 
0254     /* disable the watchdog */
0255     gpio_bit13(0x09);
0256     gpio_bit12(0x09);
0257 
0258     /* reset watchdog config register */
0259     wdt_timer_conf(0x00);
0260 
0261     /* reset watchdog control register */
0262     wdt_timer_ctrl(0x00);
0263 
0264     /* disable timeout */
0265     wdt_timeout_value(0x00);
0266 
0267     close_io_config();
0268     spin_unlock(&io_lock);
0269 }
0270 
0271 /* set timeout => enable watchdog */
0272 
0273 static void wb_smsc_wdt_set_timeout(unsigned char new_timeout)
0274 {
0275     spin_lock(&io_lock);
0276     open_io_config();
0277     select_io_device(IODEV_NO);
0278 
0279     /* set Power LED to blink, if we enable the timeout */
0280     wdt_timer_ctrl((new_timeout == 0) ? 0x00 : 0x02);
0281 
0282     /* set timeout value */
0283     wdt_timeout_value(new_timeout);
0284 
0285     close_io_config();
0286     spin_unlock(&io_lock);
0287 }
0288 
0289 /* get timeout */
0290 
0291 static unsigned char wb_smsc_wdt_get_timeout(void)
0292 {
0293     unsigned char set_timeout;
0294 
0295     spin_lock(&io_lock);
0296     open_io_config();
0297     select_io_device(IODEV_NO);
0298     set_timeout = read_io_cr(0xF2);
0299     close_io_config();
0300     spin_unlock(&io_lock);
0301 
0302     return set_timeout;
0303 }
0304 
0305 /* disable watchdog */
0306 
0307 static void wb_smsc_wdt_disable(void)
0308 {
0309     /* set the timeout to 0 to disable the watchdog */
0310     wb_smsc_wdt_set_timeout(0);
0311 }
0312 
0313 /* enable watchdog by setting the current timeout */
0314 
0315 static void wb_smsc_wdt_enable(void)
0316 {
0317     /* set the current timeout... */
0318     wb_smsc_wdt_set_timeout(timeout);
0319 }
0320 
0321 /* reset the timer */
0322 
0323 static void wb_smsc_wdt_reset_timer(void)
0324 {
0325     spin_lock(&io_lock);
0326     open_io_config();
0327     select_io_device(IODEV_NO);
0328 
0329     /* reset the timer */
0330     wdt_timeout_value(timeout);
0331     wdt_timer_conf(0x08);
0332 
0333     close_io_config();
0334     spin_unlock(&io_lock);
0335 }
0336 
0337 /* return, if the watchdog is enabled (timeout is set...) */
0338 
0339 static int wb_smsc_wdt_status(void)
0340 {
0341     return (wb_smsc_wdt_get_timeout() == 0) ? 0 : WDIOF_KEEPALIVEPING;
0342 }
0343 
0344 
0345 /* -- File operations -------------------------------------------*/
0346 
0347 /* open => enable watchdog and set initial timeout */
0348 
0349 static int wb_smsc_wdt_open(struct inode *inode, struct file *file)
0350 {
0351     /* /dev/watchdog can only be opened once */
0352 
0353     if (test_and_set_bit(0, &timer_enabled))
0354         return -EBUSY;
0355 
0356     if (nowayout)
0357         __module_get(THIS_MODULE);
0358 
0359     /* Reload and activate timer */
0360     wb_smsc_wdt_enable();
0361 
0362     pr_info("Watchdog enabled. Timeout set to %d %s\n",
0363         timeout, (unit == UNIT_SECOND) ? "second(s)" : "minute(s)");
0364 
0365     return stream_open(inode, file);
0366 }
0367 
0368 /* close => shut off the timer */
0369 
0370 static int wb_smsc_wdt_release(struct inode *inode, struct file *file)
0371 {
0372     /* Shut off the timer. */
0373 
0374     if (expect_close == 42) {
0375         wb_smsc_wdt_disable();
0376         pr_info("Watchdog disabled, sleeping again...\n");
0377     } else {
0378         pr_crit("Unexpected close, not stopping watchdog!\n");
0379         wb_smsc_wdt_reset_timer();
0380     }
0381 
0382     clear_bit(0, &timer_enabled);
0383     expect_close = 0;
0384     return 0;
0385 }
0386 
0387 /* write => update the timer to keep the machine alive */
0388 
0389 static ssize_t wb_smsc_wdt_write(struct file *file, const char __user *data,
0390                  size_t len, loff_t *ppos)
0391 {
0392     /* See if we got the magic character 'V' and reload the timer */
0393     if (len) {
0394         if (!nowayout) {
0395             size_t i;
0396 
0397             /* reset expect flag */
0398             expect_close = 0;
0399 
0400             /* scan to see whether or not we got the
0401                magic character */
0402             for (i = 0; i != len; i++) {
0403                 char c;
0404                 if (get_user(c, data + i))
0405                     return -EFAULT;
0406                 if (c == 'V')
0407                     expect_close = 42;
0408             }
0409         }
0410 
0411         /* someone wrote to us, we should reload the timer */
0412         wb_smsc_wdt_reset_timer();
0413     }
0414     return len;
0415 }
0416 
0417 /* ioctl => control interface */
0418 
0419 static long wb_smsc_wdt_ioctl(struct file *file,
0420                     unsigned int cmd, unsigned long arg)
0421 {
0422     int new_timeout;
0423 
0424     union {
0425         struct watchdog_info __user *ident;
0426         int __user *i;
0427     } uarg;
0428 
0429     static const struct watchdog_info ident = {
0430         .options =      WDIOF_KEEPALIVEPING |
0431                     WDIOF_SETTIMEOUT |
0432                     WDIOF_MAGICCLOSE,
0433         .firmware_version = 0,
0434         .identity =     "SMsC 37B787 Watchdog",
0435     };
0436 
0437     uarg.i = (int __user *)arg;
0438 
0439     switch (cmd) {
0440     case WDIOC_GETSUPPORT:
0441         return copy_to_user(uarg.ident, &ident, sizeof(ident))
0442                                 ? -EFAULT : 0;
0443     case WDIOC_GETSTATUS:
0444         return put_user(wb_smsc_wdt_status(), uarg.i);
0445     case WDIOC_GETBOOTSTATUS:
0446         return put_user(0, uarg.i);
0447     case WDIOC_SETOPTIONS:
0448     {
0449         int options, retval = -EINVAL;
0450 
0451         if (get_user(options, uarg.i))
0452             return -EFAULT;
0453 
0454         if (options & WDIOS_DISABLECARD) {
0455             wb_smsc_wdt_disable();
0456             retval = 0;
0457         }
0458         if (options & WDIOS_ENABLECARD) {
0459             wb_smsc_wdt_enable();
0460             retval = 0;
0461         }
0462         return retval;
0463     }
0464     case WDIOC_KEEPALIVE:
0465         wb_smsc_wdt_reset_timer();
0466         return 0;
0467     case WDIOC_SETTIMEOUT:
0468         if (get_user(new_timeout, uarg.i))
0469             return -EFAULT;
0470         /* the API states this is given in secs */
0471         if (unit == UNIT_MINUTE)
0472             new_timeout /= 60;
0473         if (new_timeout < 0 || new_timeout > MAX_TIMEOUT)
0474             return -EINVAL;
0475         timeout = new_timeout;
0476         wb_smsc_wdt_set_timeout(timeout);
0477         fallthrough;    /* and return the new timeout */
0478     case WDIOC_GETTIMEOUT:
0479         new_timeout = timeout;
0480         if (unit == UNIT_MINUTE)
0481             new_timeout *= 60;
0482         return put_user(new_timeout, uarg.i);
0483     default:
0484         return -ENOTTY;
0485     }
0486 }
0487 
0488 /* -- Notifier funtions -----------------------------------------*/
0489 
0490 static int wb_smsc_wdt_notify_sys(struct notifier_block *this,
0491                     unsigned long code, void *unused)
0492 {
0493     if (code == SYS_DOWN || code == SYS_HALT) {
0494         /* set timeout to 0, to avoid possible race-condition */
0495         timeout = 0;
0496         wb_smsc_wdt_disable();
0497     }
0498     return NOTIFY_DONE;
0499 }
0500 
0501 /* -- Module's structures ---------------------------------------*/
0502 
0503 static const struct file_operations wb_smsc_wdt_fops = {
0504     .owner    = THIS_MODULE,
0505     .llseek     = no_llseek,
0506     .write      = wb_smsc_wdt_write,
0507     .unlocked_ioctl = wb_smsc_wdt_ioctl,
0508     .compat_ioctl   = compat_ptr_ioctl,
0509     .open       = wb_smsc_wdt_open,
0510     .release    = wb_smsc_wdt_release,
0511 };
0512 
0513 static struct notifier_block wb_smsc_wdt_notifier = {
0514     .notifier_call  = wb_smsc_wdt_notify_sys,
0515 };
0516 
0517 static struct miscdevice wb_smsc_wdt_miscdev = {
0518     .minor      = WATCHDOG_MINOR,
0519     .name       = "watchdog",
0520     .fops       = &wb_smsc_wdt_fops,
0521 };
0522 
0523 /* -- Module init functions -------------------------------------*/
0524 
0525 /* module's "constructor" */
0526 
0527 static int __init wb_smsc_wdt_init(void)
0528 {
0529     int ret;
0530 
0531     pr_info("SMsC 37B787 watchdog component driver "
0532         VERSION " initialising...\n");
0533 
0534     if (!request_region(IOPORT, IOPORT_SIZE, "SMsC 37B787 watchdog")) {
0535         pr_err("Unable to register IO port %#x\n", IOPORT);
0536         ret = -EBUSY;
0537         goto out_pnp;
0538     }
0539 
0540     /* set new maximum, if it's too big */
0541     if (timeout > MAX_TIMEOUT)
0542         timeout = MAX_TIMEOUT;
0543 
0544     /* init the watchdog timer */
0545     wb_smsc_wdt_initialize();
0546 
0547     ret = register_reboot_notifier(&wb_smsc_wdt_notifier);
0548     if (ret) {
0549         pr_err("Unable to register reboot notifier err = %d\n", ret);
0550         goto out_io;
0551     }
0552 
0553     ret = misc_register(&wb_smsc_wdt_miscdev);
0554     if (ret) {
0555         pr_err("Unable to register miscdev on minor %d\n",
0556                WATCHDOG_MINOR);
0557         goto out_rbt;
0558     }
0559 
0560     /* output info */
0561     pr_info("Timeout set to %d %s\n",
0562         timeout, (unit == UNIT_SECOND) ? "second(s)" : "minute(s)");
0563     pr_info("Watchdog initialized and sleeping (nowayout=%d)...\n",
0564         nowayout);
0565 out_clean:
0566     return ret;
0567 
0568 out_rbt:
0569     unregister_reboot_notifier(&wb_smsc_wdt_notifier);
0570 
0571 out_io:
0572     release_region(IOPORT, IOPORT_SIZE);
0573 
0574 out_pnp:
0575     goto out_clean;
0576 }
0577 
0578 /* module's "destructor" */
0579 
0580 static void __exit wb_smsc_wdt_exit(void)
0581 {
0582     /* Stop the timer before we leave */
0583     if (!nowayout) {
0584         wb_smsc_wdt_shutdown();
0585         pr_info("Watchdog disabled\n");
0586     }
0587 
0588     misc_deregister(&wb_smsc_wdt_miscdev);
0589     unregister_reboot_notifier(&wb_smsc_wdt_notifier);
0590     release_region(IOPORT, IOPORT_SIZE);
0591 
0592     pr_info("SMsC 37B787 watchdog component driver removed\n");
0593 }
0594 
0595 module_init(wb_smsc_wdt_init);
0596 module_exit(wb_smsc_wdt_exit);
0597 
0598 MODULE_AUTHOR("Sven Anders <anders@anduras.de>");
0599 MODULE_DESCRIPTION("Driver for SMsC 37B787 watchdog component (Version "
0600                                 VERSION ")");
0601 MODULE_LICENSE("GPL");
0602 
0603 #ifdef SMSC_SUPPORT_MINUTES
0604 module_param(unit, int, 0);
0605 MODULE_PARM_DESC(unit,
0606         "set unit to use, 0=seconds or 1=minutes, default is 0");
0607 #endif
0608 
0609 module_param(timeout, int, 0);
0610 MODULE_PARM_DESC(timeout, "range is 1-255 units, default is 60");
0611 
0612 module_param(nowayout, bool, 0);
0613 MODULE_PARM_DESC(nowayout,
0614         "Watchdog cannot be stopped once started (default="
0615                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
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