drivers/watchdog/sbc7240_wdt.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  *  NANO7240 SBC Watchdog device driver
0004  *
0005  *  Based on w83877f.c by Scott Jennings,
0006  *
0007  *  (c) Copyright 2007  Gilles GIGAN <gilles.gigan@jcu.edu.au>
0008  */
0009
0010 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
0011
0012 #include <linux/fs.h>
0013 #include <linux/init.h>
0014 #include <linux/ioport.h>
0015 #include <linux/jiffies.h>
0016 #include <linux/module.h>
0017 #include <linux/moduleparam.h>
0018 #include <linux/miscdevice.h>
0019 #include <linux/notifier.h>
0020 #include <linux/reboot.h>
0021 #include <linux/types.h>
0022 #include <linux/watchdog.h>
0023 #include <linux/io.h>
0024 #include <linux/uaccess.h>
0025 #include <linux/atomic.h>
0026
0027 #define SBC7240_ENABLE_PORT     0x443
0028 #define SBC7240_DISABLE_PORT        0x043
0029 #define SBC7240_SET_TIMEOUT_PORT    SBC7240_ENABLE_PORT
0030 #define SBC7240_MAGIC_CHAR      'V'
0031
0032 #define SBC7240_TIMEOUT     30
0033 #define SBC7240_MAX_TIMEOUT     255
0034 static int timeout = SBC7240_TIMEOUT;   /* in seconds */
0035 module_param(timeout, int, 0);
0036 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (1<=timeout<="
0037          __MODULE_STRING(SBC7240_MAX_TIMEOUT) ", default="
0038          __MODULE_STRING(SBC7240_TIMEOUT) ")");
0039
0040 static bool nowayout = WATCHDOG_NOWAYOUT;
0041 module_param(nowayout, bool, 0);
0042 MODULE_PARM_DESC(nowayout, "Disable watchdog when closing device file");
0043
0044 #define SBC7240_OPEN_STATUS_BIT     0
0045 #define SBC7240_ENABLED_STATUS_BIT  1
0046 #define SBC7240_EXPECT_CLOSE_STATUS_BIT 2
0047 static unsigned long wdt_status;
0048
0049 /*
0050  * Utility routines
0051  */
0052
0053 static void wdt_disable(void)
0054 {
0055     /* disable the watchdog */
0056     if (test_and_clear_bit(SBC7240_ENABLED_STATUS_BIT, &wdt_status)) {
0057         inb_p(SBC7240_DISABLE_PORT);
0058         pr_info("Watchdog timer is now disabled\n");
0059     }
0060 }
0061
0062 static void wdt_enable(void)
0063 {
0064     /* enable the watchdog */
0065     if (!test_and_set_bit(SBC7240_ENABLED_STATUS_BIT, &wdt_status)) {
0066         inb_p(SBC7240_ENABLE_PORT);
0067         pr_info("Watchdog timer is now enabled\n");
0068     }
0069 }
0070
0071 static int wdt_set_timeout(int t)
0072 {
0073     if (t < 1 || t > SBC7240_MAX_TIMEOUT) {
0074         pr_err("timeout value must be 1<=x<=%d\n", SBC7240_MAX_TIMEOUT);
0075         return -1;
0076     }
0077     /* set the timeout */
0078     outb_p((unsigned)t, SBC7240_SET_TIMEOUT_PORT);
0079     timeout = t;
0080     pr_info("timeout set to %d seconds\n", t);
0081     return 0;
0082 }
0083
0084 /* Whack the dog */
0085 static inline void wdt_keepalive(void)
0086 {
0087     if (test_bit(SBC7240_ENABLED_STATUS_BIT, &wdt_status))
0088         inb_p(SBC7240_ENABLE_PORT);
0089 }
0090
0091 /*
0092  * /dev/watchdog handling
0093  */
0094 static ssize_t fop_write(struct file *file, const char __user *buf,
0095              size_t count, loff_t *ppos)
0096 {
0097     size_t i;
0098     char c;
0099
0100     if (count) {
0101         if (!nowayout) {
0102             clear_bit(SBC7240_EXPECT_CLOSE_STATUS_BIT,
0103                 &wdt_status);
0104
0105             /* is there a magic char ? */
0106             for (i = 0; i != count; i++) {
0107                 if (get_user(c, buf + i))
0108                     return -EFAULT;
0109                 if (c == SBC7240_MAGIC_CHAR) {
0110                     set_bit(SBC7240_EXPECT_CLOSE_STATUS_BIT,
0111                         &wdt_status);
0112                     break;
0113                 }
0114             }
0115         }
0116
0117         wdt_keepalive();
0118     }
0119
0120     return count;
0121 }
0122
0123 static int fop_open(struct inode *inode, struct file *file)
0124 {
0125     if (test_and_set_bit(SBC7240_OPEN_STATUS_BIT, &wdt_status))
0126         return -EBUSY;
0127
0128     wdt_enable();
0129
0130     return stream_open(inode, file);
0131 }
0132
0133 static int fop_close(struct inode *inode, struct file *file)
0134 {
0135     if (test_and_clear_bit(SBC7240_EXPECT_CLOSE_STATUS_BIT, &wdt_status)
0136         || !nowayout) {
0137         wdt_disable();
0138     } else {
0139         pr_crit("Unexpected close, not stopping watchdog!\n");
0140         wdt_keepalive();
0141     }
0142
0143     clear_bit(SBC7240_OPEN_STATUS_BIT, &wdt_status);
0144     return 0;
0145 }
0146
0147 static const struct watchdog_info ident = {
0148     .options = WDIOF_KEEPALIVEPING|
0149            WDIOF_SETTIMEOUT|
0150            WDIOF_MAGICCLOSE,
0151     .firmware_version = 1,
0152     .identity = "SBC7240",
0153 };
0154
0155
0156 static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
0157 {
0158     switch (cmd) {
0159     case WDIOC_GETSUPPORT:
0160         return copy_to_user((void __user *)arg, &ident, sizeof(ident))
0161                          ? -EFAULT : 0;
0162     case WDIOC_GETSTATUS:
0163     case WDIOC_GETBOOTSTATUS:
0164         return put_user(0, (int __user *)arg);
0165     case WDIOC_SETOPTIONS:
0166     {
0167         int options;
0168         int retval = -EINVAL;
0169
0170         if (get_user(options, (int __user *)arg))
0171             return -EFAULT;
0172
0173         if (options & WDIOS_DISABLECARD) {
0174             wdt_disable();
0175             retval = 0;
0176         }
0177
0178         if (options & WDIOS_ENABLECARD) {
0179             wdt_enable();
0180             retval = 0;
0181         }
0182
0183         return retval;
0184     }
0185     case WDIOC_KEEPALIVE:
0186         wdt_keepalive();
0187         return 0;
0188     case WDIOC_SETTIMEOUT:
0189     {
0190         int new_timeout;
0191
0192         if (get_user(new_timeout, (int __user *)arg))
0193             return -EFAULT;
0194
0195         if (wdt_set_timeout(new_timeout))
0196             return -EINVAL;
0197     }
0198         fallthrough;
0199     case WDIOC_GETTIMEOUT:
0200         return put_user(timeout, (int __user *)arg);
0201     default:
0202         return -ENOTTY;
0203     }
0204 }
0205
0206 static const struct file_operations wdt_fops = {
0207     .owner = THIS_MODULE,
0208     .llseek = no_llseek,
0209     .write = fop_write,
0210     .open = fop_open,
0211     .release = fop_close,
0212     .unlocked_ioctl = fop_ioctl,
0213     .compat_ioctl = compat_ptr_ioctl,
0214 };
0215
0216 static struct miscdevice wdt_miscdev = {
0217     .minor = WATCHDOG_MINOR,
0218     .name = "watchdog",
0219     .fops = &wdt_fops,
0220 };
0221
0222 /*
0223  *  Notifier for system down
0224  */
0225
0226 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
0227               void *unused)
0228 {
0229     if (code == SYS_DOWN || code == SYS_HALT)
0230         wdt_disable();
0231     return NOTIFY_DONE;
0232 }
0233
0234 static struct notifier_block wdt_notifier = {
0235     .notifier_call = wdt_notify_sys,
0236 };
0237
0238 static void __exit sbc7240_wdt_unload(void)
0239 {
0240     pr_info("Removing watchdog\n");
0241     misc_deregister(&wdt_miscdev);
0242
0243     unregister_reboot_notifier(&wdt_notifier);
0244     release_region(SBC7240_ENABLE_PORT, 1);
0245 }
0246
0247 static int __init sbc7240_wdt_init(void)
0248 {
0249     int rc = -EBUSY;
0250
0251     if (!request_region(SBC7240_ENABLE_PORT, 1, "SBC7240 WDT")) {
0252         pr_err("I/O address 0x%04x already in use\n",
0253                SBC7240_ENABLE_PORT);
0254         rc = -EIO;
0255         goto err_out;
0256     }
0257
0258     /* The IO port 0x043 used to disable the watchdog
0259      * is already claimed by the system timer, so we
0260      * can't request_region() it ...*/
0261
0262     if (timeout < 1 || timeout > SBC7240_MAX_TIMEOUT) {
0263         timeout = SBC7240_TIMEOUT;
0264         pr_info("timeout value must be 1<=x<=%d, using %d\n",
0265             SBC7240_MAX_TIMEOUT, timeout);
0266     }
0267     wdt_set_timeout(timeout);
0268     wdt_disable();
0269
0270     rc = register_reboot_notifier(&wdt_notifier);
0271     if (rc) {
0272         pr_err("cannot register reboot notifier (err=%d)\n", rc);
0273         goto err_out_region;
0274     }
0275
0276     rc = misc_register(&wdt_miscdev);
0277     if (rc) {
0278         pr_err("cannot register miscdev on minor=%d (err=%d)\n",
0279                wdt_miscdev.minor, rc);
0280         goto err_out_reboot_notifier;
0281     }
0282
0283     pr_info("Watchdog driver for SBC7240 initialised (nowayout=%d)\n",
0284         nowayout);
0285
0286     return 0;
0287
0288 err_out_reboot_notifier:
0289     unregister_reboot_notifier(&wdt_notifier);
0290 err_out_region:
0291     release_region(SBC7240_ENABLE_PORT, 1);
0292 err_out:
0293     return rc;
0294 }
0295
0296 module_init(sbc7240_wdt_init);
0297 module_exit(sbc7240_wdt_unload);
0298
0299 MODULE_AUTHOR("Gilles Gigan");
0300 MODULE_DESCRIPTION("Watchdog device driver for single board"
0301            " computers EPIC Nano 7240 from iEi");
0302 MODULE_LICENSE("GPL");