drivers/watchdog/alim1535_wdt.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  *  Watchdog for the 7101 PMU version found in the ALi M1535 chipsets
0004  */
0005
0006 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
0007
0008 #include <linux/module.h>
0009 #include <linux/moduleparam.h>
0010 #include <linux/types.h>
0011 #include <linux/miscdevice.h>
0012 #include <linux/watchdog.h>
0013 #include <linux/ioport.h>
0014 #include <linux/notifier.h>
0015 #include <linux/reboot.h>
0016 #include <linux/init.h>
0017 #include <linux/fs.h>
0018 #include <linux/pci.h>
0019 #include <linux/uaccess.h>
0020 #include <linux/io.h>
0021
0022 #define WATCHDOG_NAME "ALi_M1535"
0023 #define WATCHDOG_TIMEOUT 60 /* 60 sec default timeout */
0024
0025 /* internal variables */
0026 static unsigned long ali_is_open;
0027 static char ali_expect_release;
0028 static struct pci_dev *ali_pci;
0029 static u32 ali_timeout_bits;        /* stores the computed timeout */
0030 static DEFINE_SPINLOCK(ali_lock);   /* Guards the hardware */
0031
0032 /* module parameters */
0033 static int timeout = WATCHDOG_TIMEOUT;
0034 module_param(timeout, int, 0);
0035 MODULE_PARM_DESC(timeout,
0036         "Watchdog timeout in seconds. (0 < timeout < 18000, default="
0037                 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
0038
0039 static bool nowayout = WATCHDOG_NOWAYOUT;
0040 module_param(nowayout, bool, 0);
0041 MODULE_PARM_DESC(nowayout,
0042         "Watchdog cannot be stopped once started (default="
0043                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
0044
0045 /*
0046  *  ali_start   -   start watchdog countdown
0047  *
0048  *  Starts the timer running providing the timer has a counter
0049  *  configuration set.
0050  */
0051
0052 static void ali_start(void)
0053 {
0054     u32 val;
0055
0056     spin_lock(&ali_lock);
0057
0058     pci_read_config_dword(ali_pci, 0xCC, &val);
0059     val &= ~0x3F;   /* Mask count */
0060     val |= (1 << 25) | ali_timeout_bits;
0061     pci_write_config_dword(ali_pci, 0xCC, val);
0062
0063     spin_unlock(&ali_lock);
0064 }
0065
0066 /*
0067  *  ali_stop    -   stop the timer countdown
0068  *
0069  *  Stop the ALi watchdog countdown
0070  */
0071
0072 static void ali_stop(void)
0073 {
0074     u32 val;
0075
0076     spin_lock(&ali_lock);
0077
0078     pci_read_config_dword(ali_pci, 0xCC, &val);
0079     val &= ~0x3F;       /* Mask count to zero (disabled) */
0080     val &= ~(1 << 25);  /* and for safety mask the reset enable */
0081     pci_write_config_dword(ali_pci, 0xCC, val);
0082
0083     spin_unlock(&ali_lock);
0084 }
0085
0086 /*
0087  *  ali_keepalive   -   send a keepalive to the watchdog
0088  *
0089  *  Send a keepalive to the timer (actually we restart the timer).
0090  */
0091
0092 static void ali_keepalive(void)
0093 {
0094     ali_start();
0095 }
0096
0097 /*
0098  *  ali_settimer    -   compute the timer reload value
0099  *  @t: time in seconds
0100  *
0101  *  Computes the timeout values needed
0102  */
0103
0104 static int ali_settimer(int t)
0105 {
0106     if (t < 0)
0107         return -EINVAL;
0108     else if (t < 60)
0109         ali_timeout_bits = t|(1 << 6);
0110     else if (t < 3600)
0111         ali_timeout_bits = (t / 60)|(1 << 7);
0112     else if (t < 18000)
0113         ali_timeout_bits = (t / 300)|(1 << 6)|(1 << 7);
0114     else
0115         return -EINVAL;
0116
0117     timeout = t;
0118     return 0;
0119 }
0120
0121 /*
0122  *  /dev/watchdog handling
0123  */
0124
0125 /*
0126  *  ali_write   -   writes to ALi watchdog
0127  *  @file: file from VFS
0128  *  @data: user address of data
0129  *  @len: length of data
0130  *  @ppos: pointer to the file offset
0131  *
0132  *  Handle a write to the ALi watchdog. Writing to the file pings
0133  *  the watchdog and resets it. Writing the magic 'V' sequence allows
0134  *  the next close to turn off the watchdog.
0135  */
0136
0137 static ssize_t ali_write(struct file *file, const char __user *data,
0138                         size_t len, loff_t *ppos)
0139 {
0140     /* See if we got the magic character 'V' and reload the timer */
0141     if (len) {
0142         if (!nowayout) {
0143             size_t i;
0144
0145             /* note: just in case someone wrote the
0146                magic character five months ago... */
0147             ali_expect_release = 0;
0148
0149             /* scan to see whether or not we got
0150                the magic character */
0151             for (i = 0; i != len; i++) {
0152                 char c;
0153                 if (get_user(c, data + i))
0154                     return -EFAULT;
0155                 if (c == 'V')
0156                     ali_expect_release = 42;
0157             }
0158         }
0159
0160         /* someone wrote to us, we should reload the timer */
0161         ali_start();
0162     }
0163     return len;
0164 }
0165
0166 /*
0167  *  ali_ioctl   -   handle watchdog ioctls
0168  *  @file: VFS file pointer
0169  *  @cmd: ioctl number
0170  *  @arg: arguments to the ioctl
0171  *
0172  *  Handle the watchdog ioctls supported by the ALi driver. Really
0173  *  we want an extension to enable irq ack monitoring and the like
0174  */
0175
0176 static long ali_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
0177 {
0178     void __user *argp = (void __user *)arg;
0179     int __user *p = argp;
0180     static const struct watchdog_info ident = {
0181         .options =      WDIOF_KEEPALIVEPING |
0182                     WDIOF_SETTIMEOUT |
0183                     WDIOF_MAGICCLOSE,
0184         .firmware_version = 0,
0185         .identity =     "ALi M1535 WatchDog Timer",
0186     };
0187
0188     switch (cmd) {
0189     case WDIOC_GETSUPPORT:
0190         return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
0191
0192     case WDIOC_GETSTATUS:
0193     case WDIOC_GETBOOTSTATUS:
0194         return put_user(0, p);
0195     case WDIOC_SETOPTIONS:
0196     {
0197         int new_options, retval = -EINVAL;
0198
0199         if (get_user(new_options, p))
0200             return -EFAULT;
0201         if (new_options & WDIOS_DISABLECARD) {
0202             ali_stop();
0203             retval = 0;
0204         }
0205         if (new_options & WDIOS_ENABLECARD) {
0206             ali_start();
0207             retval = 0;
0208         }
0209         return retval;
0210     }
0211     case WDIOC_KEEPALIVE:
0212         ali_keepalive();
0213         return 0;
0214     case WDIOC_SETTIMEOUT:
0215     {
0216         int new_timeout;
0217         if (get_user(new_timeout, p))
0218             return -EFAULT;
0219         if (ali_settimer(new_timeout))
0220             return -EINVAL;
0221         ali_keepalive();
0222     }
0223         fallthrough;
0224     case WDIOC_GETTIMEOUT:
0225         return put_user(timeout, p);
0226     default:
0227         return -ENOTTY;
0228     }
0229 }
0230
0231 /*
0232  *  ali_open    -   handle open of ali watchdog
0233  *  @inode: inode from VFS
0234  *  @file: file from VFS
0235  *
0236  *  Open the ALi watchdog device. Ensure only one person opens it
0237  *  at a time. Also start the watchdog running.
0238  */
0239
0240 static int ali_open(struct inode *inode, struct file *file)
0241 {
0242     /* /dev/watchdog can only be opened once */
0243     if (test_and_set_bit(0, &ali_is_open))
0244         return -EBUSY;
0245
0246     /* Activate */
0247     ali_start();
0248     return stream_open(inode, file);
0249 }
0250
0251 /*
0252  *  ali_release -   close an ALi watchdog
0253  *  @inode: inode from VFS
0254  *  @file: file from VFS
0255  *
0256  *  Close the ALi watchdog device. Actual shutdown of the timer
0257  *  only occurs if the magic sequence has been set.
0258  */
0259
0260 static int ali_release(struct inode *inode, struct file *file)
0261 {
0262     /*
0263      *      Shut off the timer.
0264      */
0265     if (ali_expect_release == 42)
0266         ali_stop();
0267     else {
0268         pr_crit("Unexpected close, not stopping watchdog!\n");
0269         ali_keepalive();
0270     }
0271     clear_bit(0, &ali_is_open);
0272     ali_expect_release = 0;
0273     return 0;
0274 }
0275
0276 /*
0277  *  ali_notify_sys  -   System down notifier
0278  *
0279  *  Notifier for system down
0280  */
0281
0282
0283 static int ali_notify_sys(struct notifier_block *this,
0284                     unsigned long code, void *unused)
0285 {
0286     if (code == SYS_DOWN || code == SYS_HALT)
0287         ali_stop();     /* Turn the WDT off */
0288     return NOTIFY_DONE;
0289 }
0290
0291 /*
0292  *  Data for PCI driver interface
0293  *
0294  *  This data only exists for exporting the supported
0295  *  PCI ids via MODULE_DEVICE_TABLE.  We do not actually
0296  *  register a pci_driver, because someone else might one day
0297  *  want to register another driver on the same PCI id.
0298  */
0299
0300 static const struct pci_device_id ali_pci_tbl[] __used = {
0301     { PCI_VENDOR_ID_AL, 0x1533, PCI_ANY_ID, PCI_ANY_ID,},
0302     { PCI_VENDOR_ID_AL, 0x1535, PCI_ANY_ID, PCI_ANY_ID,},
0303     { 0, },
0304 };
0305 MODULE_DEVICE_TABLE(pci, ali_pci_tbl);
0306
0307 /*
0308  *  ali_find_watchdog   -   find a 1535 and 7101
0309  *
0310  *  Scans the PCI hardware for a 1535 series bridge and matching 7101
0311  *  watchdog device. This may be overtight but it is better to be safe
0312  */
0313
0314 static int __init ali_find_watchdog(void)
0315 {
0316     struct pci_dev *pdev;
0317     u32 wdog;
0318
0319     /* Check for a 1533/1535 series bridge */
0320     pdev = pci_get_device(PCI_VENDOR_ID_AL, 0x1535, NULL);
0321     if (pdev == NULL)
0322         pdev = pci_get_device(PCI_VENDOR_ID_AL, 0x1533, NULL);
0323     if (pdev == NULL)
0324         return -ENODEV;
0325     pci_dev_put(pdev);
0326
0327     /* Check for the a 7101 PMU */
0328     pdev = pci_get_device(PCI_VENDOR_ID_AL, 0x7101, NULL);
0329     if (pdev == NULL)
0330         return -ENODEV;
0331
0332     if (pci_enable_device(pdev)) {
0333         pci_dev_put(pdev);
0334         return -EIO;
0335     }
0336
0337     ali_pci = pdev;
0338
0339     /*
0340      *  Initialize the timer bits
0341      */
0342     pci_read_config_dword(pdev, 0xCC, &wdog);
0343
0344     /* Timer bits */
0345     wdog &= ~0x3F;
0346     /* Issued events */
0347     wdog &= ~((1 << 27)|(1 << 26)|(1 << 25)|(1 << 24));
0348     /* No monitor bits */
0349     wdog &= ~((1 << 16)|(1 << 13)|(1 << 12)|(1 << 11)|(1 << 10)|(1 << 9));
0350
0351     pci_write_config_dword(pdev, 0xCC, wdog);
0352
0353     return 0;
0354 }
0355
0356 /*
0357  *  Kernel Interfaces
0358  */
0359
0360 static const struct file_operations ali_fops = {
0361     .owner      =   THIS_MODULE,
0362     .llseek     =   no_llseek,
0363     .write      =   ali_write,
0364     .unlocked_ioctl =   ali_ioctl,
0365     .compat_ioctl   =   compat_ptr_ioctl,
0366     .open       =   ali_open,
0367     .release    =   ali_release,
0368 };
0369
0370 static struct miscdevice ali_miscdev = {
0371     .minor =    WATCHDOG_MINOR,
0372     .name =     "watchdog",
0373     .fops =     &ali_fops,
0374 };
0375
0376 static struct notifier_block ali_notifier = {
0377     .notifier_call =    ali_notify_sys,
0378 };
0379
0380 /*
0381  *  watchdog_init   -   module initialiser
0382  *
0383  *  Scan for a suitable watchdog and if so initialize it. Return an error
0384  *  if we cannot, the error causes the module to unload
0385  */
0386
0387 static int __init watchdog_init(void)
0388 {
0389     int ret;
0390
0391     /* Check whether or not the hardware watchdog is there */
0392     if (ali_find_watchdog() != 0)
0393         return -ENODEV;
0394
0395     /* Check that the timeout value is within it's range;
0396        if not reset to the default */
0397     if (timeout < 1 || timeout >= 18000) {
0398         timeout = WATCHDOG_TIMEOUT;
0399         pr_info("timeout value must be 0 < timeout < 18000, using %d\n",
0400             timeout);
0401     }
0402
0403     /* Calculate the watchdog's timeout */
0404     ali_settimer(timeout);
0405
0406     ret = register_reboot_notifier(&ali_notifier);
0407     if (ret != 0) {
0408         pr_err("cannot register reboot notifier (err=%d)\n", ret);
0409         goto out;
0410     }
0411
0412     ret = misc_register(&ali_miscdev);
0413     if (ret != 0) {
0414         pr_err("cannot register miscdev on minor=%d (err=%d)\n",
0415                WATCHDOG_MINOR, ret);
0416         goto unreg_reboot;
0417     }
0418
0419     pr_info("initialized. timeout=%d sec (nowayout=%d)\n",
0420         timeout, nowayout);
0421
0422 out:
0423     return ret;
0424 unreg_reboot:
0425     unregister_reboot_notifier(&ali_notifier);
0426     goto out;
0427 }
0428
0429 /*
0430  *  watchdog_exit   -   module de-initialiser
0431  *
0432  *  Called while unloading a successfully installed watchdog module.
0433  */
0434
0435 static void __exit watchdog_exit(void)
0436 {
0437     /* Stop the timer before we leave */
0438     ali_stop();
0439
0440     /* Deregister */
0441     misc_deregister(&ali_miscdev);
0442     unregister_reboot_notifier(&ali_notifier);
0443     pci_dev_put(ali_pci);
0444 }
0445
0446 module_init(watchdog_init);
0447 module_exit(watchdog_exit);
0448
0449 MODULE_AUTHOR("Alan Cox");
0450 MODULE_DESCRIPTION("ALi M1535 PMU Watchdog Timer driver");
0451 MODULE_LICENSE("GPL");