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