drivers/watchdog/cpwd.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /* cpwd.c - driver implementation for hardware watchdog
0003  * timers found on Sun Microsystems CP1400 and CP1500 boards.
0004  *
0005  * This device supports both the generic Linux watchdog
0006  * interface and Solaris-compatible ioctls as best it is
0007  * able.
0008  *
0009  * NOTE:    CP1400 systems appear to have a defective intr_mask
0010  *          register on the PLD, preventing the disabling of
0011  *          timer interrupts.  We use a timer to periodically
0012  *          reset 'stopped' watchdogs on affected platforms.
0013  *
0014  * Copyright (c) 2000 Eric Brower (ebrower@usa.net)
0015  * Copyright (C) 2008 David S. Miller <davem@davemloft.net>
0016  */
0017
0018 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
0019
0020 #include <linux/kernel.h>
0021 #include <linux/module.h>
0022 #include <linux/fs.h>
0023 #include <linux/errno.h>
0024 #include <linux/major.h>
0025 #include <linux/miscdevice.h>
0026 #include <linux/interrupt.h>
0027 #include <linux/ioport.h>
0028 #include <linux/timer.h>
0029 #include <linux/compat.h>
0030 #include <linux/slab.h>
0031 #include <linux/mutex.h>
0032 #include <linux/io.h>
0033 #include <linux/of.h>
0034 #include <linux/of_device.h>
0035 #include <linux/uaccess.h>
0036
0037 #include <asm/irq.h>
0038 #include <asm/watchdog.h>
0039
0040 #define DRIVER_NAME "cpwd"
0041
0042 #define WD_OBPNAME  "watchdog"
0043 #define WD_BADMODEL "SUNW,501-5336"
0044 #define WD_BTIMEOUT (jiffies + (HZ * 1000))
0045 #define WD_BLIMIT   0xFFFF
0046
0047 #define WD0_MINOR   212
0048 #define WD1_MINOR   213
0049 #define WD2_MINOR   214
0050
0051 /* Internal driver definitions.  */
0052 #define WD0_ID          0
0053 #define WD1_ID          1
0054 #define WD2_ID          2
0055 #define WD_NUMDEVS      3
0056
0057 #define WD_INTR_OFF     0
0058 #define WD_INTR_ON      1
0059
0060 #define WD_STAT_INIT    0x01    /* Watchdog timer is initialized    */
0061 #define WD_STAT_BSTOP   0x02    /* Watchdog timer is brokenstopped  */
0062 #define WD_STAT_SVCD    0x04    /* Watchdog interrupt occurred      */
0063
0064 /* Register value definitions
0065  */
0066 #define WD0_INTR_MASK   0x01    /* Watchdog device interrupt masks  */
0067 #define WD1_INTR_MASK   0x02
0068 #define WD2_INTR_MASK   0x04
0069
0070 #define WD_S_RUNNING    0x01    /* Watchdog device status running   */
0071 #define WD_S_EXPIRED    0x02    /* Watchdog device status expired   */
0072
0073 struct cpwd {
0074     void __iomem    *regs;
0075     spinlock_t  lock;
0076
0077     unsigned int    irq;
0078
0079     unsigned long   timeout;
0080     bool        enabled;
0081     bool        reboot;
0082     bool        broken;
0083     bool        initialized;
0084
0085     struct {
0086         struct miscdevice   misc;
0087         void __iomem        *regs;
0088         u8          intr_mask;
0089         u8          runstatus;
0090         u16         timeout;
0091     } devs[WD_NUMDEVS];
0092 };
0093
0094 static DEFINE_MUTEX(cpwd_mutex);
0095 static struct cpwd *cpwd_device;
0096
0097 /* Sun uses Altera PLD EPF8820ATC144-4
0098  * providing three hardware watchdogs:
0099  *
0100  * 1) RIC - sends an interrupt when triggered
0101  * 2) XIR - asserts XIR_B_RESET when triggered, resets CPU
0102  * 3) POR - asserts POR_B_RESET when triggered, resets CPU, backplane, board
0103  *
0104  *** Timer register block definition (struct wd_timer_regblk)
0105  *
0106  * dcntr and limit registers (halfword access):
0107  * -------------------
0108  * | 15 | ...| 1 | 0 |
0109  * -------------------
0110  * |-  counter val  -|
0111  * -------------------
0112  * dcntr -  Current 16-bit downcounter value.
0113  *          When downcounter reaches '0' watchdog expires.
0114  *          Reading this register resets downcounter with
0115  *          'limit' value.
0116  * limit -  16-bit countdown value in 1/10th second increments.
0117  *          Writing this register begins countdown with input value.
0118  *          Reading from this register does not affect counter.
0119  * NOTES:   After watchdog reset, dcntr and limit contain '1'
0120  *
0121  * status register (byte access):
0122  * ---------------------------
0123  * | 7 | ... | 2 |  1  |  0  |
0124  * --------------+------------
0125  * |-   UNUSED  -| EXP | RUN |
0126  * ---------------------------
0127  * status-  Bit 0 - Watchdog is running
0128  *          Bit 1 - Watchdog has expired
0129  *
0130  *** PLD register block definition (struct wd_pld_regblk)
0131  *
0132  * intr_mask register (byte access):
0133  * ---------------------------------
0134  * | 7 | ... | 3 |  2  |  1  |  0  |
0135  * +-------------+------------------
0136  * |-   UNUSED  -| WD3 | WD2 | WD1 |
0137  * ---------------------------------
0138  * WD3 -  1 == Interrupt disabled for watchdog 3
0139  * WD2 -  1 == Interrupt disabled for watchdog 2
0140  * WD1 -  1 == Interrupt disabled for watchdog 1
0141  *
0142  * pld_status register (byte access):
0143  * UNKNOWN, MAGICAL MYSTERY REGISTER
0144  *
0145  */
0146 #define WD_TIMER_REGSZ  16
0147 #define WD0_OFF     0
0148 #define WD1_OFF     (WD_TIMER_REGSZ * 1)
0149 #define WD2_OFF     (WD_TIMER_REGSZ * 2)
0150 #define PLD_OFF     (WD_TIMER_REGSZ * 3)
0151
0152 #define WD_DCNTR    0x00
0153 #define WD_LIMIT    0x04
0154 #define WD_STATUS   0x08
0155
0156 #define PLD_IMASK   (PLD_OFF + 0x00)
0157 #define PLD_STATUS  (PLD_OFF + 0x04)
0158
0159 static struct timer_list cpwd_timer;
0160
0161 static int wd0_timeout;
0162 static int wd1_timeout;
0163 static int wd2_timeout;
0164
0165 module_param(wd0_timeout, int, 0);
0166 MODULE_PARM_DESC(wd0_timeout, "Default watchdog0 timeout in 1/10secs");
0167 module_param(wd1_timeout, int, 0);
0168 MODULE_PARM_DESC(wd1_timeout, "Default watchdog1 timeout in 1/10secs");
0169 module_param(wd2_timeout, int, 0);
0170 MODULE_PARM_DESC(wd2_timeout, "Default watchdog2 timeout in 1/10secs");
0171
0172 MODULE_AUTHOR("Eric Brower <ebrower@usa.net>");
0173 MODULE_DESCRIPTION("Hardware watchdog driver for Sun Microsystems CP1400/1500");
0174 MODULE_LICENSE("GPL");
0175
0176 static void cpwd_writew(u16 val, void __iomem *addr)
0177 {
0178     writew(cpu_to_le16(val), addr);
0179 }
0180 static u16 cpwd_readw(void __iomem *addr)
0181 {
0182     u16 val = readw(addr);
0183
0184     return le16_to_cpu(val);
0185 }
0186
0187 static void cpwd_writeb(u8 val, void __iomem *addr)
0188 {
0189     writeb(val, addr);
0190 }
0191
0192 static u8 cpwd_readb(void __iomem *addr)
0193 {
0194     return readb(addr);
0195 }
0196
0197 /* Enable or disable watchdog interrupts
0198  * Because of the CP1400 defect this should only be
0199  * called during initialzation or by wd_[start|stop]timer()
0200  *
0201  * index    - sub-device index, or -1 for 'all'
0202  * enable   - non-zero to enable interrupts, zero to disable
0203  */
0204 static void cpwd_toggleintr(struct cpwd *p, int index, int enable)
0205 {
0206     unsigned char curregs = cpwd_readb(p->regs + PLD_IMASK);
0207     unsigned char setregs =
0208         (index == -1) ?
0209         (WD0_INTR_MASK | WD1_INTR_MASK | WD2_INTR_MASK) :
0210         (p->devs[index].intr_mask);
0211
0212     if (enable == WD_INTR_ON)
0213         curregs &= ~setregs;
0214     else
0215         curregs |= setregs;
0216
0217     cpwd_writeb(curregs, p->regs + PLD_IMASK);
0218 }
0219
0220 /* Restarts timer with maximum limit value and
0221  * does not unset 'brokenstop' value.
0222  */
0223 static void cpwd_resetbrokentimer(struct cpwd *p, int index)
0224 {
0225     cpwd_toggleintr(p, index, WD_INTR_ON);
0226     cpwd_writew(WD_BLIMIT, p->devs[index].regs + WD_LIMIT);
0227 }
0228
0229 /* Timer method called to reset stopped watchdogs--
0230  * because of the PLD bug on CP1400, we cannot mask
0231  * interrupts within the PLD so me must continually
0232  * reset the timers ad infinitum.
0233  */
0234 static void cpwd_brokentimer(struct timer_list *unused)
0235 {
0236     struct cpwd *p = cpwd_device;
0237     int id, tripped = 0;
0238
0239     /* kill a running timer instance, in case we
0240      * were called directly instead of by kernel timer
0241      */
0242     if (timer_pending(&cpwd_timer))
0243         del_timer(&cpwd_timer);
0244
0245     for (id = 0; id < WD_NUMDEVS; id++) {
0246         if (p->devs[id].runstatus & WD_STAT_BSTOP) {
0247             ++tripped;
0248             cpwd_resetbrokentimer(p, id);
0249         }
0250     }
0251
0252     if (tripped) {
0253         /* there is at least one timer brokenstopped-- reschedule */
0254         cpwd_timer.expires = WD_BTIMEOUT;
0255         add_timer(&cpwd_timer);
0256     }
0257 }
0258
0259 /* Reset countdown timer with 'limit' value and continue countdown.
0260  * This will not start a stopped timer.
0261  */
0262 static void cpwd_pingtimer(struct cpwd *p, int index)
0263 {
0264     if (cpwd_readb(p->devs[index].regs + WD_STATUS) & WD_S_RUNNING)
0265         cpwd_readw(p->devs[index].regs + WD_DCNTR);
0266 }
0267
0268 /* Stop a running watchdog timer-- the timer actually keeps
0269  * running, but the interrupt is masked so that no action is
0270  * taken upon expiration.
0271  */
0272 static void cpwd_stoptimer(struct cpwd *p, int index)
0273 {
0274     if (cpwd_readb(p->devs[index].regs + WD_STATUS) & WD_S_RUNNING) {
0275         cpwd_toggleintr(p, index, WD_INTR_OFF);
0276
0277         if (p->broken) {
0278             p->devs[index].runstatus |= WD_STAT_BSTOP;
0279             cpwd_brokentimer(NULL);
0280         }
0281     }
0282 }
0283
0284 /* Start a watchdog timer with the specified limit value
0285  * If the watchdog is running, it will be restarted with
0286  * the provided limit value.
0287  *
0288  * This function will enable interrupts on the specified
0289  * watchdog.
0290  */
0291 static void cpwd_starttimer(struct cpwd *p, int index)
0292 {
0293     if (p->broken)
0294         p->devs[index].runstatus &= ~WD_STAT_BSTOP;
0295
0296     p->devs[index].runstatus &= ~WD_STAT_SVCD;
0297
0298     cpwd_writew(p->devs[index].timeout, p->devs[index].regs + WD_LIMIT);
0299     cpwd_toggleintr(p, index, WD_INTR_ON);
0300 }
0301
0302 static int cpwd_getstatus(struct cpwd *p, int index)
0303 {
0304     unsigned char stat = cpwd_readb(p->devs[index].regs + WD_STATUS);
0305     unsigned char intr = cpwd_readb(p->devs[index].regs + PLD_IMASK);
0306     unsigned char ret  = WD_STOPPED;
0307
0308     /* determine STOPPED */
0309     if (!stat)
0310         return ret;
0311
0312     /* determine EXPIRED vs FREERUN vs RUNNING */
0313     else if (WD_S_EXPIRED & stat) {
0314         ret = WD_EXPIRED;
0315     } else if (WD_S_RUNNING & stat) {
0316         if (intr & p->devs[index].intr_mask) {
0317             ret = WD_FREERUN;
0318         } else {
0319             /* Fudge WD_EXPIRED status for defective CP1400--
0320              * IF timer is running
0321              *  AND brokenstop is set
0322              *  AND an interrupt has been serviced
0323              * we are WD_EXPIRED.
0324              *
0325              * IF timer is running
0326              *  AND brokenstop is set
0327              *  AND no interrupt has been serviced
0328              * we are WD_FREERUN.
0329              */
0330             if (p->broken &&
0331                 (p->devs[index].runstatus & WD_STAT_BSTOP)) {
0332                 if (p->devs[index].runstatus & WD_STAT_SVCD) {
0333                     ret = WD_EXPIRED;
0334                 } else {
0335                     /* we could as well pretend
0336                      * we are expired */
0337                     ret = WD_FREERUN;
0338                 }
0339             } else {
0340                 ret = WD_RUNNING;
0341             }
0342         }
0343     }
0344
0345     /* determine SERVICED */
0346     if (p->devs[index].runstatus & WD_STAT_SVCD)
0347         ret |= WD_SERVICED;
0348
0349     return ret;
0350 }
0351
0352 static irqreturn_t cpwd_interrupt(int irq, void *dev_id)
0353 {
0354     struct cpwd *p = dev_id;
0355
0356     /* Only WD0 will interrupt-- others are NMI and we won't
0357      * see them here....
0358      */
0359     spin_lock_irq(&p->lock);
0360
0361     cpwd_stoptimer(p, WD0_ID);
0362     p->devs[WD0_ID].runstatus |=  WD_STAT_SVCD;
0363
0364     spin_unlock_irq(&p->lock);
0365
0366     return IRQ_HANDLED;
0367 }
0368
0369 static int cpwd_open(struct inode *inode, struct file *f)
0370 {
0371     struct cpwd *p = cpwd_device;
0372
0373     mutex_lock(&cpwd_mutex);
0374     switch (iminor(inode)) {
0375     case WD0_MINOR:
0376     case WD1_MINOR:
0377     case WD2_MINOR:
0378         break;
0379
0380     default:
0381         mutex_unlock(&cpwd_mutex);
0382         return -ENODEV;
0383     }
0384
0385     /* Register IRQ on first open of device */
0386     if (!p->initialized) {
0387         if (request_irq(p->irq, &cpwd_interrupt,
0388                 IRQF_SHARED, DRIVER_NAME, p)) {
0389             pr_err("Cannot register IRQ %d\n", p->irq);
0390             mutex_unlock(&cpwd_mutex);
0391             return -EBUSY;
0392         }
0393         p->initialized = true;
0394     }
0395
0396     mutex_unlock(&cpwd_mutex);
0397
0398     return stream_open(inode, f);
0399 }
0400
0401 static int cpwd_release(struct inode *inode, struct file *file)
0402 {
0403     return 0;
0404 }
0405
0406 static long cpwd_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
0407 {
0408     static const struct watchdog_info info = {
0409         .options        = WDIOF_SETTIMEOUT,
0410         .firmware_version   = 1,
0411         .identity       = DRIVER_NAME,
0412     };
0413     void __user *argp = (void __user *)arg;
0414     struct inode *inode = file_inode(file);
0415     int index = iminor(inode) - WD0_MINOR;
0416     struct cpwd *p = cpwd_device;
0417     int setopt = 0;
0418
0419     switch (cmd) {
0420     /* Generic Linux IOCTLs */
0421     case WDIOC_GETSUPPORT:
0422         if (copy_to_user(argp, &info, sizeof(struct watchdog_info)))
0423             return -EFAULT;
0424         break;
0425
0426     case WDIOC_GETSTATUS:
0427     case WDIOC_GETBOOTSTATUS:
0428         if (put_user(0, (int __user *)argp))
0429             return -EFAULT;
0430         break;
0431
0432     case WDIOC_KEEPALIVE:
0433         cpwd_pingtimer(p, index);
0434         break;
0435
0436     case WDIOC_SETOPTIONS:
0437         if (copy_from_user(&setopt, argp, sizeof(unsigned int)))
0438             return -EFAULT;
0439
0440         if (setopt & WDIOS_DISABLECARD) {
0441             if (p->enabled)
0442                 return -EINVAL;
0443             cpwd_stoptimer(p, index);
0444         } else if (setopt & WDIOS_ENABLECARD) {
0445             cpwd_starttimer(p, index);
0446         } else {
0447             return -EINVAL;
0448         }
0449         break;
0450
0451     /* Solaris-compatible IOCTLs */
0452     case WIOCGSTAT:
0453         setopt = cpwd_getstatus(p, index);
0454         if (copy_to_user(argp, &setopt, sizeof(unsigned int)))
0455             return -EFAULT;
0456         break;
0457
0458     case WIOCSTART:
0459         cpwd_starttimer(p, index);
0460         break;
0461
0462     case WIOCSTOP:
0463         if (p->enabled)
0464             return -EINVAL;
0465
0466         cpwd_stoptimer(p, index);
0467         break;
0468
0469     default:
0470         return -EINVAL;
0471     }
0472
0473     return 0;
0474 }
0475
0476 static long cpwd_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
0477 {
0478     return cpwd_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
0479 }
0480
0481 static ssize_t cpwd_write(struct file *file, const char __user *buf,
0482               size_t count, loff_t *ppos)
0483 {
0484     struct inode *inode = file_inode(file);
0485     struct cpwd *p = cpwd_device;
0486     int index = iminor(inode);
0487
0488     if (count) {
0489         cpwd_pingtimer(p, index);
0490         return 1;
0491     }
0492
0493     return 0;
0494 }
0495
0496 static ssize_t cpwd_read(struct file *file, char __user *buffer,
0497              size_t count, loff_t *ppos)
0498 {
0499     return -EINVAL;
0500 }
0501
0502 static const struct file_operations cpwd_fops = {
0503     .owner =        THIS_MODULE,
0504     .unlocked_ioctl =   cpwd_ioctl,
0505     .compat_ioctl =     cpwd_compat_ioctl,
0506     .open =         cpwd_open,
0507     .write =        cpwd_write,
0508     .read =         cpwd_read,
0509     .release =      cpwd_release,
0510     .llseek =       no_llseek,
0511 };
0512
0513 static int cpwd_probe(struct platform_device *op)
0514 {
0515     struct device_node *options;
0516     const char *str_prop;
0517     const void *prop_val;
0518     int i, err = -EINVAL;
0519     struct cpwd *p;
0520
0521     if (cpwd_device)
0522         return -EINVAL;
0523
0524     p = devm_kzalloc(&op->dev, sizeof(*p), GFP_KERNEL);
0525     if (!p)
0526         return -ENOMEM;
0527
0528     p->irq = op->archdata.irqs[0];
0529
0530     spin_lock_init(&p->lock);
0531
0532     p->regs = of_ioremap(&op->resource[0], 0,
0533                  4 * WD_TIMER_REGSZ, DRIVER_NAME);
0534     if (!p->regs) {
0535         pr_err("Unable to map registers\n");
0536         return -ENOMEM;
0537     }
0538
0539     options = of_find_node_by_path("/options");
0540     if (!options) {
0541         err = -ENODEV;
0542         pr_err("Unable to find /options node\n");
0543         goto out_iounmap;
0544     }
0545
0546     prop_val = of_get_property(options, "watchdog-enable?", NULL);
0547     p->enabled = (prop_val ? true : false);
0548
0549     prop_val = of_get_property(options, "watchdog-reboot?", NULL);
0550     p->reboot = (prop_val ? true : false);
0551
0552     str_prop = of_get_property(options, "watchdog-timeout", NULL);
0553     if (str_prop)
0554         p->timeout = simple_strtoul(str_prop, NULL, 10);
0555
0556     of_node_put(options);
0557
0558     /* CP1400s seem to have broken PLD implementations-- the
0559      * interrupt_mask register cannot be written, so no timer
0560      * interrupts can be masked within the PLD.
0561      */
0562     str_prop = of_get_property(op->dev.of_node, "model", NULL);
0563     p->broken = (str_prop && !strcmp(str_prop, WD_BADMODEL));
0564
0565     if (!p->enabled)
0566         cpwd_toggleintr(p, -1, WD_INTR_OFF);
0567
0568     for (i = 0; i < WD_NUMDEVS; i++) {
0569         static const char *cpwd_names[] = { "RIC", "XIR", "POR" };
0570         static int *parms[] = { &wd0_timeout,
0571                     &wd1_timeout,
0572                     &wd2_timeout };
0573         struct miscdevice *mp = &p->devs[i].misc;
0574
0575         mp->minor = WD0_MINOR + i;
0576         mp->name = cpwd_names[i];
0577         mp->fops = &cpwd_fops;
0578
0579         p->devs[i].regs = p->regs + (i * WD_TIMER_REGSZ);
0580         p->devs[i].intr_mask = (WD0_INTR_MASK << i);
0581         p->devs[i].runstatus &= ~WD_STAT_BSTOP;
0582         p->devs[i].runstatus |= WD_STAT_INIT;
0583         p->devs[i].timeout = p->timeout;
0584         if (*parms[i])
0585             p->devs[i].timeout = *parms[i];
0586
0587         err = misc_register(&p->devs[i].misc);
0588         if (err) {
0589             pr_err("Could not register misc device for dev %d\n",
0590                    i);
0591             goto out_unregister;
0592         }
0593     }
0594
0595     if (p->broken) {
0596         timer_setup(&cpwd_timer, cpwd_brokentimer, 0);
0597         cpwd_timer.expires  = WD_BTIMEOUT;
0598
0599         pr_info("PLD defect workaround enabled for model %s\n",
0600             WD_BADMODEL);
0601     }
0602
0603     platform_set_drvdata(op, p);
0604     cpwd_device = p;
0605     return 0;
0606
0607 out_unregister:
0608     for (i--; i >= 0; i--)
0609         misc_deregister(&p->devs[i].misc);
0610
0611 out_iounmap:
0612     of_iounmap(&op->resource[0], p->regs, 4 * WD_TIMER_REGSZ);
0613
0614     return err;
0615 }
0616
0617 static int cpwd_remove(struct platform_device *op)
0618 {
0619     struct cpwd *p = platform_get_drvdata(op);
0620     int i;
0621
0622     for (i = 0; i < WD_NUMDEVS; i++) {
0623         misc_deregister(&p->devs[i].misc);
0624
0625         if (!p->enabled) {
0626             cpwd_stoptimer(p, i);
0627             if (p->devs[i].runstatus & WD_STAT_BSTOP)
0628                 cpwd_resetbrokentimer(p, i);
0629         }
0630     }
0631
0632     if (p->broken)
0633         del_timer_sync(&cpwd_timer);
0634
0635     if (p->initialized)
0636         free_irq(p->irq, p);
0637
0638     of_iounmap(&op->resource[0], p->regs, 4 * WD_TIMER_REGSZ);
0639
0640     cpwd_device = NULL;
0641
0642     return 0;
0643 }
0644
0645 static const struct of_device_id cpwd_match[] = {
0646     {
0647         .name = "watchdog",
0648     },
0649     {},
0650 };
0651 MODULE_DEVICE_TABLE(of, cpwd_match);
0652
0653 static struct platform_driver cpwd_driver = {
0654     .driver = {
0655         .name = DRIVER_NAME,
0656         .of_match_table = cpwd_match,
0657     },
0658     .probe      = cpwd_probe,
0659     .remove     = cpwd_remove,
0660 };
0661
0662 module_platform_driver(cpwd_driver);