drivers/watchdog/sbc_fitpc2_wdt.c

   1 /*
   2  * Watchdog driver for SBC-FITPC2 board
   3  *
   4  * Author: Denis Turischev <denis@compulab.co.il>
   5  *
   6  * Adapted from the IXP2000 watchdog driver by Deepak Saxena.
   7  *
   8  * This file is licensed under  the terms of the GNU General Public
   9  * License version 2. This program is licensed "as is" without any
  10  * warranty of any kind, whether express or implied.
  11  */
  12
  13 #define pr_fmt(fmt) KBUILD_MODNAME " WATCHDOG: " fmt
  14
  15 #include <linux/module.h>
  16 #include <linux/types.h>
  17 #include <linux/miscdevice.h>
  18 #include <linux/watchdog.h>
  19 #include <linux/ioport.h>
  20 #include <linux/delay.h>
  21 #include <linux/fs.h>
  22 #include <linux/init.h>
  23 #include <linux/moduleparam.h>
  24 #include <linux/dmi.h>
  25 #include <linux/io.h>
  26 #include <linux/uaccess.h>
  27
  28
  29 static bool nowayout = WATCHDOG_NOWAYOUT;
  30 static unsigned int margin = 60;        /* (secs) Default is 1 minute */
  31 static unsigned long wdt_status;
  32 static DEFINE_MUTEX(wdt_lock);
  33
  34 #define WDT_IN_USE              0
  35 #define WDT_OK_TO_CLOSE         1
  36
  37 #define COMMAND_PORT            0x4c
  38 #define DATA_PORT               0x48
  39
  40 #define IFACE_ON_COMMAND        1
  41 #define REBOOT_COMMAND          2
  42
  43 #define WATCHDOG_NAME           "SBC-FITPC2 Watchdog"
  44
  45 static void wdt_send_data(unsigned char command, unsigned char data)
  46 {
  47         outb(data, DATA_PORT);
  48         msleep(200);
  49         outb(command, COMMAND_PORT);
  50         msleep(100);
  51 }
  52
  53 static void wdt_enable(void)
  54 {
  55         mutex_lock(&wdt_lock);
  56         wdt_send_data(IFACE_ON_COMMAND, 1);
  57         wdt_send_data(REBOOT_COMMAND, margin);
  58         mutex_unlock(&wdt_lock);
  59 }
  60
  61 static void wdt_disable(void)
  62 {
  63         mutex_lock(&wdt_lock);
  64         wdt_send_data(IFACE_ON_COMMAND, 0);
  65         wdt_send_data(REBOOT_COMMAND, 0);
  66         mutex_unlock(&wdt_lock);
  67 }
  68
  69 static int fitpc2_wdt_open(struct inode *inode, struct file *file)
  70 {
  71         if (test_and_set_bit(WDT_IN_USE, &wdt_status))
  72                 return -EBUSY;
  73
  74         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  75
  76         wdt_enable();
  77
  78         return stream_open(inode, file);
  79 }
  80
  81 static ssize_t fitpc2_wdt_write(struct file *file, const char __user *data,
  82                                                 size_t len, loff_t *ppos)
  83 {
  84         size_t i;
  85
  86         if (!len)
  87                 return 0;
  88
  89         if (nowayout) {
  90                 len = 0;
  91                 goto out;
  92         }
  93
  94         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  95
  96         for (i = 0; i != len; i++) {
  97                 char c;
  98
  99                 if (get_user(c, data + i))
 100                         return -EFAULT;
 101
 102                 if (c == 'V')
 103                         set_bit(WDT_OK_TO_CLOSE, &wdt_status);
 104         }
 105
 106 out:
 107         wdt_enable();
 108
 109         return len;
 110 }
 111
 112
 113 static const struct watchdog_info ident = {
 114         .options        = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT |
 115                                 WDIOF_KEEPALIVEPING,
 116         .identity       = WATCHDOG_NAME,
 117 };
 118
 119
 120 static long fitpc2_wdt_ioctl(struct file *file, unsigned int cmd,
 121                                                         unsigned long arg)
 122 {
 123         int ret = -ENOTTY;
 124         int time;
 125
 126         switch (cmd) {
 127         case WDIOC_GETSUPPORT:
 128                 ret = copy_to_user((struct watchdog_info __user *)arg, &ident,
 129                                    sizeof(ident)) ? -EFAULT : 0;
 130                 break;
 131
 132         case WDIOC_GETSTATUS:
 133                 ret = put_user(0, (int __user *)arg);
 134                 break;
 135
 136         case WDIOC_GETBOOTSTATUS:
 137                 ret = put_user(0, (int __user *)arg);
 138                 break;
 139
 140         case WDIOC_KEEPALIVE:
 141                 wdt_enable();
 142                 ret = 0;
 143                 break;
 144
 145         case WDIOC_SETTIMEOUT:
 146                 ret = get_user(time, (int __user *)arg);
 147                 if (ret)
 148                         break;
 149
 150                 if (time < 31 || time > 255) {
 151                         ret = -EINVAL;
 152                         break;
 153                 }
 154
 155                 margin = time;
 156                 wdt_enable();
 157                 fallthrough;
 158
 159         case WDIOC_GETTIMEOUT:
 160                 ret = put_user(margin, (int __user *)arg);
 161                 break;
 162         }
 163
 164         return ret;
 165 }
 166
 167 static int fitpc2_wdt_release(struct inode *inode, struct file *file)
 168 {
 169         if (test_bit(WDT_OK_TO_CLOSE, &wdt_status)) {
 170                 wdt_disable();
 171                 pr_info("Device disabled\n");
 172         } else {
 173                 pr_warn("Device closed unexpectedly - timer will not stop\n");
 174                 wdt_enable();
 175         }
 176
 177         clear_bit(WDT_IN_USE, &wdt_status);
 178         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 179
 180         return 0;
 181 }
 182
 183
 184 static const struct file_operations fitpc2_wdt_fops = {
 185         .owner          = THIS_MODULE,
 186         .llseek         = no_llseek,
 187         .write          = fitpc2_wdt_write,
 188         .unlocked_ioctl = fitpc2_wdt_ioctl,
 189         .compat_ioctl   = compat_ptr_ioctl,
 190         .open           = fitpc2_wdt_open,
 191         .release        = fitpc2_wdt_release,
 192 };
 193
 194 static struct miscdevice fitpc2_wdt_miscdev = {
 195         .minor          = WATCHDOG_MINOR,
 196         .name           = "watchdog",
 197         .fops           = &fitpc2_wdt_fops,
 198 };
 199
 200 static int __init fitpc2_wdt_init(void)
 201 {
 202         int err;
 203         const char *brd_name;
 204
 205         brd_name = dmi_get_system_info(DMI_BOARD_NAME);
 206
 207         if (!brd_name || !strstr(brd_name, "SBC-FITPC2"))
 208                 return -ENODEV;
 209
 210         pr_info("%s found\n", brd_name);
 211
 212         if (!request_region(COMMAND_PORT, 1, WATCHDOG_NAME)) {
 213                 pr_err("I/O address 0x%04x already in use\n", COMMAND_PORT);
 214                 return -EIO;
 215         }
 216
 217         if (!request_region(DATA_PORT, 1, WATCHDOG_NAME)) {
 218                 pr_err("I/O address 0x%04x already in use\n", DATA_PORT);
 219                 err = -EIO;
 220                 goto err_data_port;
 221         }
 222
 223         if (margin < 31 || margin > 255) {
 224                 pr_err("margin must be in range 31 - 255 seconds, you tried to set %d\n",
 225                        margin);
 226                 err = -EINVAL;
 227                 goto err_margin;
 228         }
 229
 230         err = misc_register(&fitpc2_wdt_miscdev);
 231         if (err) {
 232                 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
 233                        WATCHDOG_MINOR, err);
 234                 goto err_margin;
 235         }
 236
 237         return 0;
 238
 239 err_margin:
 240         release_region(DATA_PORT, 1);
 241 err_data_port:
 242         release_region(COMMAND_PORT, 1);
 243
 244         return err;
 245 }
 246
 247 static void __exit fitpc2_wdt_exit(void)
 248 {
 249         misc_deregister(&fitpc2_wdt_miscdev);
 250         release_region(DATA_PORT, 1);
 251         release_region(COMMAND_PORT, 1);
 252 }
 253
 254 module_init(fitpc2_wdt_init);
 255 module_exit(fitpc2_wdt_exit);
 256
 257 MODULE_AUTHOR("Denis Turischev <denis@compulab.co.il>");
 258 MODULE_DESCRIPTION("SBC-FITPC2 Watchdog");
 259
 260 module_param(margin, int, 0);
 261 MODULE_PARM_DESC(margin, "Watchdog margin in seconds (default 60s)");
 262
 263 module_param(nowayout, bool, 0);
 264 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
 265
 266 MODULE_LICENSE("GPL");