drivers/watchdog/orion5x_wdt.c

   1 /*
   2  * drivers/watchdog/orion5x_wdt.c
   3  *
   4  * Watchdog driver for Orion5x processors
   5  *
   6  * Author: Sylver Bruneau <sylver.bruneau@googlemail.com>
   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 #include <linux/module.h>
  14 #include <linux/moduleparam.h>
  15 #include <linux/types.h>
  16 #include <linux/kernel.h>
  17 #include <linux/fs.h>
  18 #include <linux/miscdevice.h>
  19 #include <linux/watchdog.h>
  20 #include <linux/init.h>
  21 #include <linux/uaccess.h>
  22 #include <linux/io.h>
  23 #include <linux/spinlock.h>
  24
  25 /*
  26  * Watchdog timer block registers.
  27  */
  28 #define TIMER_CTRL              (TIMER_VIRT_BASE + 0x0000)
  29 #define  WDT_EN                 0x0010
  30 #define WDT_VAL                 (TIMER_VIRT_BASE + 0x0024)
  31
  32 #define ORION5X_TCLK            166666667
  33 #define WDT_MAX_DURATION        (0xffffffff / ORION5X_TCLK)
  34 #define WDT_IN_USE              0
  35 #define WDT_OK_TO_CLOSE         1
  36
  37 static int nowayout = WATCHDOG_NOWAYOUT;
  38 static int heartbeat =  WDT_MAX_DURATION;       /* (seconds) */
  39 static unsigned long wdt_status;
  40 static spinlock_t wdt_lock;
  41
  42 static void wdt_enable(void)
  43 {
  44         u32 reg;
  45
  46         spin_lock(&wdt_lock);
  47
  48         /* Set watchdog duration */
  49         writel(ORION5X_TCLK * heartbeat, WDT_VAL);
  50
  51         /* Clear watchdog timer interrupt */
  52         reg = readl(BRIDGE_CAUSE);
  53         reg &= ~WDT_INT_REQ;
  54         writel(reg, BRIDGE_CAUSE);
  55
  56         /* Enable watchdog timer */
  57         reg = readl(TIMER_CTRL);
  58         reg |= WDT_EN;
  59         writel(reg, TIMER_CTRL);
  60
  61         /* Enable reset on watchdog */
  62         reg = readl(CPU_RESET_MASK);
  63         reg |= WDT_RESET;
  64         writel(reg, CPU_RESET_MASK);
  65
  66         spin_unlock(&wdt_lock);
  67 }
  68
  69 static void wdt_disable(void)
  70 {
  71         u32 reg;
  72
  73         spin_lock(&wdt_lock);
  74
  75         /* Disable reset on watchdog */
  76         reg = readl(CPU_RESET_MASK);
  77         reg &= ~WDT_RESET;
  78         writel(reg, CPU_RESET_MASK);
  79
  80         /* Disable watchdog timer */
  81         reg = readl(TIMER_CTRL);
  82         reg &= ~WDT_EN;
  83         writel(reg, TIMER_CTRL);
  84
  85         spin_unlock(&wdt_lock);
  86 }
  87
  88 static int orion5x_wdt_get_timeleft(int *time_left)
  89 {
  90         spin_lock(&wdt_lock);
  91         *time_left = readl(WDT_VAL) / ORION5X_TCLK;
  92         spin_unlock(&wdt_lock);
  93         return 0;
  94 }
  95
  96 static int orion5x_wdt_open(struct inode *inode, struct file *file)
  97 {
  98         if (test_and_set_bit(WDT_IN_USE, &wdt_status))
  99                 return -EBUSY;
 100         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 101         wdt_enable();
 102         return nonseekable_open(inode, file);
 103 }
 104
 105 static ssize_t orion5x_wdt_write(struct file *file, const char *data,
 106                                         size_t len, loff_t *ppos)
 107 {
 108         if (len) {
 109                 if (!nowayout) {
 110                         size_t i;
 111
 112                         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 113                         for (i = 0; i != len; i++) {
 114                                 char c;
 115
 116                                 if (get_user(c, data + i))
 117                                         return -EFAULT;
 118                                 if (c == 'V')
 119                                         set_bit(WDT_OK_TO_CLOSE, &wdt_status);
 120                         }
 121                 }
 122                 wdt_enable();
 123         }
 124         return len;
 125 }
 126
 127 static struct watchdog_info ident = {
 128         .options        = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT |
 129                           WDIOF_KEEPALIVEPING,
 130         .identity       = "Orion5x Watchdog",
 131 };
 132
 133
 134 static long orion5x_wdt_ioctl(struct file *file, unsigned int cmd,
 135                                 unsigned long arg)
 136 {
 137         int ret = -ENOTTY;
 138         int time;
 139
 140         switch (cmd) {
 141         case WDIOC_GETSUPPORT:
 142                 ret = copy_to_user((struct watchdog_info *)arg, &ident,
 143                                    sizeof(ident)) ? -EFAULT : 0;
 144                 break;
 145
 146         case WDIOC_GETSTATUS:
 147         case WDIOC_GETBOOTSTATUS:
 148                 ret = put_user(0, (int *)arg);
 149                 break;
 150
 151         case WDIOC_KEEPALIVE:
 152                 wdt_enable();
 153                 ret = 0;
 154                 break;
 155
 156         case WDIOC_SETTIMEOUT:
 157                 ret = get_user(time, (int *)arg);
 158                 if (ret)
 159                         break;
 160
 161                 if (time <= 0 || time > WDT_MAX_DURATION) {
 162                         ret = -EINVAL;
 163                         break;
 164                 }
 165                 heartbeat = time;
 166                 wdt_enable();
 167                 /* Fall through */
 168
 169         case WDIOC_GETTIMEOUT:
 170                 ret = put_user(heartbeat, (int *)arg);
 171                 break;
 172
 173         case WDIOC_GETTIMELEFT:
 174                 if (orion5x_wdt_get_timeleft(&time)) {
 175                         ret = -EINVAL;
 176                         break;
 177                 }
 178                 ret = put_user(time, (int *)arg);
 179                 break;
 180         }
 181         return ret;
 182 }
 183
 184 static int orion5x_wdt_release(struct inode *inode, struct file *file)
 185 {
 186         if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
 187                 wdt_disable();
 188         else
 189                 printk(KERN_CRIT "WATCHDOG: Device closed unexpectedly - "
 190                                         "timer will not stop\n");
 191         clear_bit(WDT_IN_USE, &wdt_status);
 192         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 193
 194         return 0;
 195 }
 196
 197
 198 static const struct file_operations orion5x_wdt_fops = {
 199         .owner          = THIS_MODULE,
 200         .llseek         = no_llseek,
 201         .write          = orion5x_wdt_write,
 202         .unlocked_ioctl = orion5x_wdt_ioctl,
 203         .open           = orion5x_wdt_open,
 204         .release        = orion5x_wdt_release,
 205 };
 206
 207 static struct miscdevice orion5x_wdt_miscdev = {
 208         .minor          = WATCHDOG_MINOR,
 209         .name           = "watchdog",
 210         .fops           = &orion5x_wdt_fops,
 211 };
 212
 213 static int __init orion5x_wdt_init(void)
 214 {
 215         int ret;
 216
 217         spin_lock_init(&wdt_lock);
 218
 219         ret = misc_register(&orion5x_wdt_miscdev);
 220         if (ret == 0)
 221                 printk("Orion5x Watchdog Timer: heartbeat %d sec\n",
 222                                                                 heartbeat);
 223
 224         return ret;
 225 }
 226
 227 static void __exit orion5x_wdt_exit(void)
 228 {
 229         misc_deregister(&orion5x_wdt_miscdev);
 230 }
 231
 232 module_init(orion5x_wdt_init);
 233 module_exit(orion5x_wdt_exit);
 234
 235 MODULE_AUTHOR("Sylver Bruneau <sylver.bruneau@googlemail.com>");
 236 MODULE_DESCRIPTION("Orion5x Processor Watchdog");
 237
 238 module_param(heartbeat, int, 0);
 239 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds (default is "
 240                                         __MODULE_STRING(WDT_MAX_DURATION) ")");
 241
 242 module_param(nowayout, int, 0);
 243 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
 244
 245 MODULE_LICENSE("GPL");
 246 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);