drivers/watchdog/pika_wdt.c

   1 /*
   2  * PIKA FPGA based Watchdog Timer
   3  *
   4  * Copyright (c) 2008 PIKA Technologies
   5  *   Sean MacLennan <smaclennan@pikatech.com>
   6  */
   7
   8 #include <linux/init.h>
   9 #include <linux/errno.h>
  10 #include <linux/module.h>
  11 #include <linux/moduleparam.h>
  12 #include <linux/types.h>
  13 #include <linux/kernel.h>
  14 #include <linux/fs.h>
  15 #include <linux/miscdevice.h>
  16 #include <linux/watchdog.h>
  17 #include <linux/reboot.h>
  18 #include <linux/jiffies.h>
  19 #include <linux/timer.h>
  20 #include <linux/bitops.h>
  21 #include <linux/uaccess.h>
  22 #include <linux/io.h>
  23 #include <linux/of_platform.h>
  24
  25 #define DRV_NAME "PIKA-WDT"
  26 #define PFX DRV_NAME ": "
  27
  28 /* Hardware timeout in seconds */
  29 #define WDT_HW_TIMEOUT 2
  30
  31 /* Timer heartbeat (500ms) */
  32 #define WDT_TIMEOUT     (HZ/2)
  33
  34 /* User land timeout */
  35 #define WDT_HEARTBEAT 15
  36 static int heartbeat = WDT_HEARTBEAT;
  37 module_param(heartbeat, int, 0);
  38 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. "
  39         "(default = " __MODULE_STRING(WDT_HEARTBEAT) ")");
  40
  41 static int nowayout = WATCHDOG_NOWAYOUT;
  42 module_param(nowayout, int, 0);
  43 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
  44         "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  45
  46 static struct {
  47         void __iomem *fpga;
  48         unsigned long next_heartbeat;   /* the next_heartbeat for the timer */
  49         unsigned long open;
  50         char expect_close;
  51         int bootstatus;
  52         struct timer_list timer;        /* The timer that pings the watchdog */
  53 } pikawdt_private;
  54
  55 static const struct watchdog_info ident = {
  56         .identity       = DRV_NAME,
  57         .options        = WDIOF_CARDRESET |
  58                           WDIOF_SETTIMEOUT |
  59                           WDIOF_KEEPALIVEPING |
  60                           WDIOF_MAGICCLOSE,
  61 };
  62
  63 /*
  64  * Reload the watchdog timer.  (ie, pat the watchdog)
  65  */
  66 static inline void pikawdt_reset(void)
  67 {
  68         /* -- FPGA: Reset Control Register (32bit R/W) (Offset: 0x14) --
  69          * Bit 7,    WTCHDG_EN: When set to 1, the watchdog timer is enabled.
  70          *           Once enabled, it cannot be disabled. The watchdog can be
  71          *           kicked by performing any write access to the reset
  72          *           control register (this register).
  73          * Bit 8-11, WTCHDG_TIMEOUT_SEC: Sets the watchdog timeout value in
  74          *           seconds. Valid ranges are 1 to 15 seconds. The value can
  75          *           be modified dynamically.
  76          */
  77         unsigned reset = in_be32(pikawdt_private.fpga + 0x14);
  78         /* enable with max timeout - 15 seconds */
  79         reset |= (1 << 7) + (WDT_HW_TIMEOUT << 8);
  80         out_be32(pikawdt_private.fpga + 0x14, reset);
  81 }
  82
  83 /*
  84  * Timer tick
  85  */
  86 static void pikawdt_ping(unsigned long data)
  87 {
  88         if (time_before(jiffies, pikawdt_private.next_heartbeat) ||
  89                         (!nowayout && !pikawdt_private.open)) {
  90                 pikawdt_reset();
  91                 mod_timer(&pikawdt_private.timer, jiffies + WDT_TIMEOUT);
  92         } else
  93                 printk(KERN_CRIT PFX "I will reset your machine !\n");
  94 }
  95
  96
  97 static void pikawdt_keepalive(void)
  98 {
  99         pikawdt_private.next_heartbeat = jiffies + heartbeat * HZ;
 100 }
 101
 102 static void pikawdt_start(void)
 103 {
 104         pikawdt_keepalive();
 105         mod_timer(&pikawdt_private.timer, jiffies + WDT_TIMEOUT);
 106 }
 107
 108 /*
 109  * Watchdog device is opened, and watchdog starts running.
 110  */
 111 static int pikawdt_open(struct inode *inode, struct file *file)
 112 {
 113         /* /dev/watchdog can only be opened once */
 114         if (test_and_set_bit(0, &pikawdt_private.open))
 115                 return -EBUSY;
 116
 117         pikawdt_start();
 118
 119         return nonseekable_open(inode, file);
 120 }
 121
 122 /*
 123  * Close the watchdog device.
 124  */
 125 static int pikawdt_release(struct inode *inode, struct file *file)
 126 {
 127         /* stop internal ping */
 128         if (!pikawdt_private.expect_close)
 129                 del_timer(&pikawdt_private.timer);
 130
 131         clear_bit(0, &pikawdt_private.open);
 132         pikawdt_private.expect_close = 0;
 133         return 0;
 134 }
 135
 136 /*
 137  * Pat the watchdog whenever device is written to.
 138  */
 139 static ssize_t pikawdt_write(struct file *file, const char __user *data,
 140                              size_t len, loff_t *ppos)
 141 {
 142         if (!len)
 143                 return 0;
 144
 145         /* Scan for magic character */
 146         if (!nowayout) {
 147                 size_t i;
 148
 149                 pikawdt_private.expect_close = 0;
 150
 151                 for (i = 0; i < len; i++) {
 152                         char c;
 153                         if (get_user(c, data + i))
 154                                 return -EFAULT;
 155                         if (c == 'V') {
 156                                 pikawdt_private.expect_close = 42;
 157                                 break;
 158                         }
 159                 }
 160         }
 161
 162         pikawdt_keepalive();
 163
 164         return len;
 165 }
 166
 167 /*
 168  * Handle commands from user-space.
 169  */
 170 static long pikawdt_ioctl(struct file *file,
 171                 unsigned int cmd, unsigned long arg)
 172 {
 173         void __user *argp = (void __user *)arg;
 174         int __user *p = argp;
 175         int new_value;
 176
 177         switch (cmd) {
 178         case WDIOC_GETSUPPORT:
 179                 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
 180
 181         case WDIOC_GETSTATUS:
 182                 return put_user(0, p);
 183
 184         case WDIOC_GETBOOTSTATUS:
 185                 return put_user(pikawdt_private.bootstatus, p);
 186
 187         case WDIOC_KEEPALIVE:
 188                 pikawdt_keepalive();
 189                 return 0;
 190
 191         case WDIOC_SETTIMEOUT:
 192                 if (get_user(new_value, p))
 193                         return -EFAULT;
 194
 195                 heartbeat = new_value;
 196                 pikawdt_keepalive();
 197
 198                 return put_user(new_value, p);  /* return current value */
 199
 200         case WDIOC_GETTIMEOUT:
 201                 return put_user(heartbeat, p);
 202         }
 203         return -ENOTTY;
 204 }
 205
 206
 207 static const struct file_operations pikawdt_fops = {
 208         .owner          = THIS_MODULE,
 209         .llseek         = no_llseek,
 210         .open           = pikawdt_open,
 211         .release        = pikawdt_release,
 212         .write          = pikawdt_write,
 213         .unlocked_ioctl = pikawdt_ioctl,
 214 };
 215
 216 static struct miscdevice pikawdt_miscdev = {
 217         .minor  = WATCHDOG_MINOR,
 218         .name   = "watchdog",
 219         .fops   = &pikawdt_fops,
 220 };
 221
 222 static int __init pikawdt_init(void)
 223 {
 224         struct device_node *np;
 225         void __iomem *fpga;
 226         static u32 post1;
 227         int ret;
 228
 229         np = of_find_compatible_node(NULL, NULL, "pika,fpga");
 230         if (np == NULL) {
 231                 printk(KERN_ERR PFX "Unable to find fpga.\n");
 232                 return -ENOENT;
 233         }
 234
 235         pikawdt_private.fpga = of_iomap(np, 0);
 236         of_node_put(np);
 237         if (pikawdt_private.fpga == NULL) {
 238                 printk(KERN_ERR PFX "Unable to map fpga.\n");
 239                 return -ENOMEM;
 240         }
 241
 242         ident.firmware_version = in_be32(pikawdt_private.fpga + 0x1c) & 0xffff;
 243
 244         /* POST information is in the sd area. */
 245         np = of_find_compatible_node(NULL, NULL, "pika,fpga-sd");
 246         if (np == NULL) {
 247                 printk(KERN_ERR PFX "Unable to find fpga-sd.\n");
 248                 ret = -ENOENT;
 249                 goto out;
 250         }
 251
 252         fpga = of_iomap(np, 0);
 253         of_node_put(np);
 254         if (fpga == NULL) {
 255                 printk(KERN_ERR PFX "Unable to map fpga-sd.\n");
 256                 ret = -ENOMEM;
 257                 goto out;
 258         }
 259
 260         /* -- FPGA: POST Test Results Register 1 (32bit R/W) (Offset: 0x4040) --
 261          * Bit 31,   WDOG: Set to 1 when the last reset was caused by a watchdog
 262          *           timeout.
 263          */
 264         post1 = in_be32(fpga + 0x40);
 265         if (post1 & 0x80000000)
 266                 pikawdt_private.bootstatus = WDIOF_CARDRESET;
 267
 268         iounmap(fpga);
 269
 270         setup_timer(&pikawdt_private.timer, pikawdt_ping, 0);
 271
 272         ret = misc_register(&pikawdt_miscdev);
 273         if (ret) {
 274                 printk(KERN_ERR PFX "Unable to register miscdev.\n");
 275                 goto out;
 276         }
 277
 278         printk(KERN_INFO PFX "initialized. heartbeat=%d sec (nowayout=%d)\n",
 279                                                         heartbeat, nowayout);
 280         return 0;
 281
 282 out:
 283         iounmap(pikawdt_private.fpga);
 284         return ret;
 285 }
 286
 287 static void __exit pikawdt_exit(void)
 288 {
 289         misc_deregister(&pikawdt_miscdev);
 290
 291         iounmap(pikawdt_private.fpga);
 292 }
 293
 294 module_init(pikawdt_init);
 295 module_exit(pikawdt_exit);
 296
 297 MODULE_AUTHOR("Sean MacLennan <smaclennan@pikatech.com>");
 298 MODULE_DESCRIPTION("PIKA FPGA based Watchdog Timer");
 299 MODULE_LICENSE("GPL");
 300 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 301