drivers/watchdog/sbc_fitpc2_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Watchdog driver for SBC-FITPC2 board
   4  *
   5  * Author: Denis Turischev <denis@compulab.co.il>
   6  *
   7  * Adapted from the IXP2000 watchdog driver by Deepak Saxena.
   8  *
   9  */
  10
  11 #define pr_fmt(fmt) KBUILD_MODNAME " WATCHDOG: " fmt
  12
  13 #include <linux/module.h>
  14 #include <linux/types.h>
  15 #include <linux/miscdevice.h>
  16 #include <linux/watchdog.h>
  17 #include <linux/ioport.h>
  18 #include <linux/delay.h>
  19 #include <linux/fs.h>
  20 #include <linux/init.h>
  21 #include <linux/moduleparam.h>
  22 #include <linux/dmi.h>
  23 #include <linux/io.h>
  24 #include <linux/uaccess.h>
  25
  26
  27 static bool nowayout = WATCHDOG_NOWAYOUT;
  28 static unsigned int margin = 60;        /* (secs) Default is 1 minute */
  29 static unsigned long wdt_status;
  30 static DEFINE_MUTEX(wdt_lock);
  31
  32 #define WDT_IN_USE              0
  33 #define WDT_OK_TO_CLOSE         1
  34
  35 #define COMMAND_PORT            0x4c
  36 #define DATA_PORT               0x48
  37
  38 #define IFACE_ON_COMMAND        1
  39 #define REBOOT_COMMAND          2
  40
  41 #define WATCHDOG_NAME           "SBC-FITPC2 Watchdog"
  42
  43 static void wdt_send_data(unsigned char command, unsigned char data)
  44 {
  45         outb(data, DATA_PORT);
  46         msleep(200);
  47         outb(command, COMMAND_PORT);
  48         msleep(100);
  49 }
  50
  51 static void wdt_enable(void)
  52 {
  53         mutex_lock(&wdt_lock);
  54         wdt_send_data(IFACE_ON_COMMAND, 1);
  55         wdt_send_data(REBOOT_COMMAND, margin);
  56         mutex_unlock(&wdt_lock);
  57 }
  58
  59 static void wdt_disable(void)
  60 {
  61         mutex_lock(&wdt_lock);
  62         wdt_send_data(IFACE_ON_COMMAND, 0);
  63         wdt_send_data(REBOOT_COMMAND, 0);
  64         mutex_unlock(&wdt_lock);
  65 }
  66
  67 static int fitpc2_wdt_open(struct inode *inode, struct file *file)
  68 {
  69         if (test_and_set_bit(WDT_IN_USE, &wdt_status))
  70                 return -EBUSY;
  71
  72         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  73
  74         wdt_enable();
  75
  76         return stream_open(inode, file);
  77 }
  78
  79 static ssize_t fitpc2_wdt_write(struct file *file, const char __user *data,
  80                                                 size_t len, loff_t *ppos)
  81 {
  82         size_t i;
  83
  84         if (!len)
  85                 return 0;
  86
  87         if (nowayout) {
  88                 len = 0;
  89                 goto out;
  90         }
  91
  92         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  93
  94         for (i = 0; i != len; i++) {
  95                 char c;
  96
  97                 if (get_user(c, data + i))
  98                         return -EFAULT;
  99
 100                 if (c == 'V')
 101                         set_bit(WDT_OK_TO_CLOSE, &wdt_status);
 102         }
 103
 104 out:
 105         wdt_enable();
 106
 107         return len;
 108 }
 109
 110
 111 static const struct watchdog_info ident = {
 112         .options        = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT |
 113                                 WDIOF_KEEPALIVEPING,
 114         .identity       = WATCHDOG_NAME,
 115 };
 116
 117
 118 static long fitpc2_wdt_ioctl(struct file *file, unsigned int cmd,
 119                                                         unsigned long arg)
 120 {
 121         int ret = -ENOTTY;
 122         int time;
 123
 124         switch (cmd) {
 125         case WDIOC_GETSUPPORT:
 126                 ret = copy_to_user((struct watchdog_info __user *)arg, &ident,
 127                                    sizeof(ident)) ? -EFAULT : 0;
 128                 break;
 129
 130         case WDIOC_GETSTATUS:
 131                 ret = put_user(0, (int __user *)arg);
 132                 break;
 133
 134         case WDIOC_GETBOOTSTATUS:
 135                 ret = put_user(0, (int __user *)arg);
 136                 break;
 137
 138         case WDIOC_KEEPALIVE:
 139                 wdt_enable();
 140                 ret = 0;
 141                 break;
 142
 143         case WDIOC_SETTIMEOUT:
 144                 ret = get_user(time, (int __user *)arg);
 145                 if (ret)
 146                         break;
 147
 148                 if (time < 31 || time > 255) {
 149                         ret = -EINVAL;
 150                         break;
 151                 }
 152
 153                 margin = time;
 154                 wdt_enable();
 155                 fallthrough;
 156
 157         case WDIOC_GETTIMEOUT:
 158                 ret = put_user(margin, (int __user *)arg);
 159                 break;
 160         }
 161
 162         return ret;
 163 }
 164
 165 static int fitpc2_wdt_release(struct inode *inode, struct file *file)
 166 {
 167         if (test_bit(WDT_OK_TO_CLOSE, &wdt_status)) {
 168                 wdt_disable();
 169                 pr_info("Device disabled\n");
 170         } else {
 171                 pr_warn("Device closed unexpectedly - timer will not stop\n");
 172                 wdt_enable();
 173         }
 174
 175         clear_bit(WDT_IN_USE, &wdt_status);
 176         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 177
 178         return 0;
 179 }
 180
 181
 182 static const struct file_operations fitpc2_wdt_fops = {
 183         .owner          = THIS_MODULE,
 184         .write          = fitpc2_wdt_write,
 185         .unlocked_ioctl = fitpc2_wdt_ioctl,
 186         .compat_ioctl   = compat_ptr_ioctl,
 187         .open           = fitpc2_wdt_open,
 188         .release        = fitpc2_wdt_release,
 189 };
 190
 191 static struct miscdevice fitpc2_wdt_miscdev = {
 192         .minor          = WATCHDOG_MINOR,
 193         .name           = "watchdog",
 194         .fops           = &fitpc2_wdt_fops,
 195 };
 196
 197 static int __init fitpc2_wdt_init(void)
 198 {
 199         int err;
 200         const char *brd_name;
 201
 202         brd_name = dmi_get_system_info(DMI_BOARD_NAME);
 203
 204         if (!brd_name || !strstr(brd_name, "SBC-FITPC2"))
 205                 return -ENODEV;
 206
 207         pr_info("%s found\n", brd_name);
 208
 209         if (!request_region(COMMAND_PORT, 1, WATCHDOG_NAME)) {
 210                 pr_err("I/O address 0x%04x already in use\n", COMMAND_PORT);
 211                 return -EIO;
 212         }
 213
 214         if (!request_region(DATA_PORT, 1, WATCHDOG_NAME)) {
 215                 pr_err("I/O address 0x%04x already in use\n", DATA_PORT);
 216                 err = -EIO;
 217                 goto err_data_port;
 218         }
 219
 220         if (margin < 31 || margin > 255) {
 221                 pr_err("margin must be in range 31 - 255 seconds, you tried to set %d\n",
 222                        margin);
 223                 err = -EINVAL;
 224                 goto err_margin;
 225         }
 226
 227         err = misc_register(&fitpc2_wdt_miscdev);
 228         if (err) {
 229                 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
 230                        WATCHDOG_MINOR, err);
 231                 goto err_margin;
 232         }
 233
 234         return 0;
 235
 236 err_margin:
 237         release_region(DATA_PORT, 1);
 238 err_data_port:
 239         release_region(COMMAND_PORT, 1);
 240
 241         return err;
 242 }
 243
 244 static void __exit fitpc2_wdt_exit(void)
 245 {
 246         misc_deregister(&fitpc2_wdt_miscdev);
 247         release_region(DATA_PORT, 1);
 248         release_region(COMMAND_PORT, 1);
 249 }
 250
 251 module_init(fitpc2_wdt_init);
 252 module_exit(fitpc2_wdt_exit);
 253
 254 MODULE_AUTHOR("Denis Turischev <denis@compulab.co.il>");
 255 MODULE_DESCRIPTION("SBC-FITPC2 Watchdog");
 256
 257 module_param(margin, int, 0);
 258 MODULE_PARM_DESC(margin, "Watchdog margin in seconds (default 60s)");
 259
 260 module_param(nowayout, bool, 0);
 261 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
 262
 263 MODULE_LICENSE("GPL");