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 #include <asm/system.h>
  29
  30 static int nowayout = WATCHDOG_NOWAYOUT;
  31 static unsigned int margin = 60;        /* (secs) Default is 1 minute */
  32 static unsigned long wdt_status;
  33 static DEFINE_MUTEX(wdt_lock);
  34
  35 #define WDT_IN_USE              0
  36 #define WDT_OK_TO_CLOSE         1
  37
  38 #define COMMAND_PORT            0x4c
  39 #define DATA_PORT               0x48
  40
  41 #define IFACE_ON_COMMAND        1
  42 #define REBOOT_COMMAND          2
  43
  44 #define WATCHDOG_NAME           "SBC-FITPC2 Watchdog"
  45
  46 static void wdt_send_data(unsigned char command, unsigned char data)
  47 {
  48         outb(data, DATA_PORT);
  49         msleep(200);
  50         outb(command, COMMAND_PORT);
  51         msleep(100);
  52 }
  53
  54 static void wdt_enable(void)
  55 {
  56         mutex_lock(&wdt_lock);
  57         wdt_send_data(IFACE_ON_COMMAND, 1);
  58         wdt_send_data(REBOOT_COMMAND, margin);
  59         mutex_unlock(&wdt_lock);
  60 }
  61
  62 static void wdt_disable(void)
  63 {
  64         mutex_lock(&wdt_lock);
  65         wdt_send_data(IFACE_ON_COMMAND, 0);
  66         wdt_send_data(REBOOT_COMMAND, 0);
  67         mutex_unlock(&wdt_lock);
  68 }
  69
  70 static int fitpc2_wdt_open(struct inode *inode, struct file *file)
  71 {
  72         if (test_and_set_bit(WDT_IN_USE, &wdt_status))
  73                 return -EBUSY;
  74
  75         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  76
  77         wdt_enable();
  78
  79         return nonseekable_open(inode, file);
  80 }
  81
  82 static ssize_t fitpc2_wdt_write(struct file *file, const char *data,
  83                                                 size_t len, loff_t *ppos)
  84 {
  85         size_t i;
  86
  87         if (!len)
  88                 return 0;
  89
  90         if (nowayout) {
  91                 len = 0;
  92                 goto out;
  93         }
  94
  95         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  96
  97         for (i = 0; i != len; i++) {
  98                 char c;
  99
 100                 if (get_user(c, data + i))
 101                         return -EFAULT;
 102
 103                 if (c == 'V')
 104                         set_bit(WDT_OK_TO_CLOSE, &wdt_status);
 105         }
 106
 107 out:
 108         wdt_enable();
 109
 110         return len;
 111 }
 112
 113
 114 static const struct watchdog_info ident = {
 115         .options        = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT |
 116                                 WDIOF_KEEPALIVEPING,
 117         .identity       = WATCHDOG_NAME,
 118 };
 119
 120
 121 static long fitpc2_wdt_ioctl(struct file *file, unsigned int cmd,
 122                                                         unsigned long arg)
 123 {
 124         int ret = -ENOTTY;
 125         int time;
 126
 127         switch (cmd) {
 128         case WDIOC_GETSUPPORT:
 129                 ret = copy_to_user((struct watchdog_info *)arg, &ident,
 130                                    sizeof(ident)) ? -EFAULT : 0;
 131                 break;
 132
 133         case WDIOC_GETSTATUS:
 134                 ret = put_user(0, (int *)arg);
 135                 break;
 136
 137         case WDIOC_GETBOOTSTATUS:
 138                 ret = put_user(0, (int *)arg);
 139                 break;
 140
 141         case WDIOC_KEEPALIVE:
 142                 wdt_enable();
 143                 ret = 0;
 144                 break;
 145
 146         case WDIOC_SETTIMEOUT:
 147                 ret = get_user(time, (int *)arg);
 148                 if (ret)
 149                         break;
 150
 151                 if (time < 31 || time > 255) {
 152                         ret = -EINVAL;
 153                         break;
 154                 }
 155
 156                 margin = time;
 157                 wdt_enable();
 158                 /* Fall through */
 159
 160         case WDIOC_GETTIMEOUT:
 161                 ret = put_user(margin, (int *)arg);
 162                 break;
 163         }
 164
 165         return ret;
 166 }
 167
 168 static int fitpc2_wdt_release(struct inode *inode, struct file *file)
 169 {
 170         if (test_bit(WDT_OK_TO_CLOSE, &wdt_status)) {
 171                 wdt_disable();
 172                 pr_info("Device disabled\n");
 173         } else {
 174                 pr_warning("Device closed unexpectedly -"
 175                         " timer will not stop\n");
 176                 wdt_enable();
 177         }
 178
 179         clear_bit(WDT_IN_USE, &wdt_status);
 180         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 181
 182         return 0;
 183 }
 184
 185
 186 static const struct file_operations fitpc2_wdt_fops = {
 187         .owner          = THIS_MODULE,
 188         .llseek         = no_llseek,
 189         .write          = fitpc2_wdt_write,
 190         .unlocked_ioctl = fitpc2_wdt_ioctl,
 191         .open           = fitpc2_wdt_open,
 192         .release        = fitpc2_wdt_release,
 193 };
 194
 195 static struct miscdevice fitpc2_wdt_miscdev = {
 196         .minor          = WATCHDOG_MINOR,
 197         .name           = "watchdog",
 198         .fops           = &fitpc2_wdt_fops,
 199 };
 200
 201 static int __init fitpc2_wdt_init(void)
 202 {
 203         int err;
 204         const char *brd_name;
 205
 206         brd_name = dmi_get_system_info(DMI_BOARD_NAME);
 207
 208         if (!brd_name || !strstr(brd_name, "SBC-FITPC2"))
 209                 return -ENODEV;
 210
 211         pr_info("%s found\n", brd_name);
 212
 213         if (!request_region(COMMAND_PORT, 1, WATCHDOG_NAME)) {
 214                 pr_err("I/O address 0x%04x already in use\n", COMMAND_PORT);
 215                 return -EIO;
 216         }
 217
 218         if (!request_region(DATA_PORT, 1, WATCHDOG_NAME)) {
 219                 pr_err("I/O address 0x%04x already in use\n", DATA_PORT);
 220                 err = -EIO;
 221                 goto err_data_port;
 222         }
 223
 224         if (margin < 31 || margin > 255) {
 225                 pr_err("margin must be in range 31 - 255"
 226                        " seconds, you tried to set %d\n", margin);
 227                 err = -EINVAL;
 228                 goto err_margin;
 229         }
 230
 231         err = misc_register(&fitpc2_wdt_miscdev);
 232         if (err) {
 233                 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
 234                                                         WATCHDOG_MINOR, err);
 235                 goto err_margin;
 236         }
 237
 238         return 0;
 239
 240 err_margin:
 241         release_region(DATA_PORT, 1);
 242 err_data_port:
 243         release_region(COMMAND_PORT, 1);
 244
 245         return err;
 246 }
 247
 248 static void __exit fitpc2_wdt_exit(void)
 249 {
 250         misc_deregister(&fitpc2_wdt_miscdev);
 251         release_region(DATA_PORT, 1);
 252         release_region(COMMAND_PORT, 1);
 253 }
 254
 255 module_init(fitpc2_wdt_init);
 256 module_exit(fitpc2_wdt_exit);
 257
 258 MODULE_AUTHOR("Denis Turischev <denis@compulab.co.il>");
 259 MODULE_DESCRIPTION("SBC-FITPC2 Watchdog");
 260
 261 module_param(margin, int, 0);
 262 MODULE_PARM_DESC(margin, "Watchdog margin in seconds (default 60s)");
 263
 264 module_param(nowayout, int, 0);
 265 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
 266
 267 MODULE_LICENSE("GPL");
 268 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 269