drivers/watchdog/pika_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * PIKA FPGA based Watchdog Timer
   4  *
   5  * Copyright (c) 2008 PIKA Technologies
   6  *   Sean MacLennan <smaclennan@pikatech.com>
   7  */
   8
   9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  10
  11 #include <linux/init.h>
  12 #include <linux/errno.h>
  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/reboot.h>
  21 #include <linux/jiffies.h>
  22 #include <linux/timer.h>
  23 #include <linux/bitops.h>
  24 #include <linux/uaccess.h>
  25 #include <linux/io.h>
  26 #include <linux/of_address.h>
  27 #include <linux/of_platform.h>
  28
  29 #define DRV_NAME "PIKA-WDT"
  30
  31 /* Hardware timeout in seconds */
  32 #define WDT_HW_TIMEOUT 2
  33
  34 /* Timer heartbeat (500ms) */
  35 #define WDT_TIMEOUT     (HZ/2)
  36
  37 /* User land timeout */
  38 #define WDT_HEARTBEAT 15
  39 static int heartbeat = WDT_HEARTBEAT;
  40 module_param(heartbeat, int, 0);
  41 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. "
  42         "(default = " __MODULE_STRING(WDT_HEARTBEAT) ")");
  43
  44 static bool nowayout = WATCHDOG_NOWAYOUT;
  45 module_param(nowayout, bool, 0);
  46 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
  47         "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  48
  49 static struct {
  50         void __iomem *fpga;
  51         unsigned long next_heartbeat;   /* the next_heartbeat for the timer */
  52         unsigned long open;
  53         char expect_close;
  54         int bootstatus;
  55         struct timer_list timer;        /* The timer that pings the watchdog */
  56 } pikawdt_private;
  57
  58 static struct watchdog_info ident __ro_after_init = {
  59         .identity       = DRV_NAME,
  60         .options        = WDIOF_CARDRESET |
  61                           WDIOF_SETTIMEOUT |
  62                           WDIOF_KEEPALIVEPING |
  63                           WDIOF_MAGICCLOSE,
  64 };
  65
  66 /*
  67  * Reload the watchdog timer.  (ie, pat the watchdog)
  68  */
  69 static inline void pikawdt_reset(void)
  70 {
  71         /* -- FPGA: Reset Control Register (32bit R/W) (Offset: 0x14) --
  72          * Bit 7,    WTCHDG_EN: When set to 1, the watchdog timer is enabled.
  73          *           Once enabled, it cannot be disabled. The watchdog can be
  74          *           kicked by performing any write access to the reset
  75          *           control register (this register).
  76          * Bit 8-11, WTCHDG_TIMEOUT_SEC: Sets the watchdog timeout value in
  77          *           seconds. Valid ranges are 1 to 15 seconds. The value can
  78          *           be modified dynamically.
  79          */
  80         unsigned reset = in_be32(pikawdt_private.fpga + 0x14);
  81         /* enable with max timeout - 15 seconds */
  82         reset |= (1 << 7) + (WDT_HW_TIMEOUT << 8);
  83         out_be32(pikawdt_private.fpga + 0x14, reset);
  84 }
  85
  86 /*
  87  * Timer tick
  88  */
  89 static void pikawdt_ping(struct timer_list *unused)
  90 {
  91         if (time_before(jiffies, pikawdt_private.next_heartbeat) ||
  92                         (!nowayout && !pikawdt_private.open)) {
  93                 pikawdt_reset();
  94                 mod_timer(&pikawdt_private.timer, jiffies + WDT_TIMEOUT);
  95         } else
  96                 pr_crit("I will reset your machine !\n");
  97 }
  98
  99
 100 static void pikawdt_keepalive(void)
 101 {
 102         pikawdt_private.next_heartbeat = jiffies + heartbeat * HZ;
 103 }
 104
 105 static void pikawdt_start(void)
 106 {
 107         pikawdt_keepalive();
 108         mod_timer(&pikawdt_private.timer, jiffies + WDT_TIMEOUT);
 109 }
 110
 111 /*
 112  * Watchdog device is opened, and watchdog starts running.
 113  */
 114 static int pikawdt_open(struct inode *inode, struct file *file)
 115 {
 116         /* /dev/watchdog can only be opened once */
 117         if (test_and_set_bit(0, &pikawdt_private.open))
 118                 return -EBUSY;
 119
 120         pikawdt_start();
 121
 122         return stream_open(inode, file);
 123 }
 124
 125 /*
 126  * Close the watchdog device.
 127  */
 128 static int pikawdt_release(struct inode *inode, struct file *file)
 129 {
 130         /* stop internal ping */
 131         if (!pikawdt_private.expect_close)
 132                 del_timer(&pikawdt_private.timer);
 133
 134         clear_bit(0, &pikawdt_private.open);
 135         pikawdt_private.expect_close = 0;
 136         return 0;
 137 }
 138
 139 /*
 140  * Pat the watchdog whenever device is written to.
 141  */
 142 static ssize_t pikawdt_write(struct file *file, const char __user *data,
 143                              size_t len, loff_t *ppos)
 144 {
 145         if (!len)
 146                 return 0;
 147
 148         /* Scan for magic character */
 149         if (!nowayout) {
 150                 size_t i;
 151
 152                 pikawdt_private.expect_close = 0;
 153
 154                 for (i = 0; i < len; i++) {
 155                         char c;
 156                         if (get_user(c, data + i))
 157                                 return -EFAULT;
 158                         if (c == 'V') {
 159                                 pikawdt_private.expect_close = 42;
 160                                 break;
 161                         }
 162                 }
 163         }
 164
 165         pikawdt_keepalive();
 166
 167         return len;
 168 }
 169
 170 /*
 171  * Handle commands from user-space.
 172  */
 173 static long pikawdt_ioctl(struct file *file,
 174                 unsigned int cmd, unsigned long arg)
 175 {
 176         void __user *argp = (void __user *)arg;
 177         int __user *p = argp;
 178         int new_value;
 179
 180         switch (cmd) {
 181         case WDIOC_GETSUPPORT:
 182                 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
 183
 184         case WDIOC_GETSTATUS:
 185                 return put_user(0, p);
 186
 187         case WDIOC_GETBOOTSTATUS:
 188                 return put_user(pikawdt_private.bootstatus, p);
 189
 190         case WDIOC_KEEPALIVE:
 191                 pikawdt_keepalive();
 192                 return 0;
 193
 194         case WDIOC_SETTIMEOUT:
 195                 if (get_user(new_value, p))
 196                         return -EFAULT;
 197
 198                 heartbeat = new_value;
 199                 pikawdt_keepalive();
 200
 201                 return put_user(new_value, p);  /* return current value */
 202
 203         case WDIOC_GETTIMEOUT:
 204                 return put_user(heartbeat, p);
 205         }
 206         return -ENOTTY;
 207 }
 208
 209
 210 static const struct file_operations pikawdt_fops = {
 211         .owner          = THIS_MODULE,
 212         .llseek         = no_llseek,
 213         .open           = pikawdt_open,
 214         .release        = pikawdt_release,
 215         .write          = pikawdt_write,
 216         .unlocked_ioctl = pikawdt_ioctl,
 217 };
 218
 219 static struct miscdevice pikawdt_miscdev = {
 220         .minor  = WATCHDOG_MINOR,
 221         .name   = "watchdog",
 222         .fops   = &pikawdt_fops,
 223 };
 224
 225 static int __init pikawdt_init(void)
 226 {
 227         struct device_node *np;
 228         void __iomem *fpga;
 229         u32 post1;
 230         int ret;
 231
 232         np = of_find_compatible_node(NULL, NULL, "pika,fpga");
 233         if (np == NULL) {
 234                 pr_err("Unable to find fpga\n");
 235                 return -ENOENT;
 236         }
 237
 238         pikawdt_private.fpga = of_iomap(np, 0);
 239         of_node_put(np);
 240         if (pikawdt_private.fpga == NULL) {
 241                 pr_err("Unable to map fpga\n");
 242                 return -ENOMEM;
 243         }
 244
 245         ident.firmware_version = in_be32(pikawdt_private.fpga + 0x1c) & 0xffff;
 246
 247         /* POST information is in the sd area. */
 248         np = of_find_compatible_node(NULL, NULL, "pika,fpga-sd");
 249         if (np == NULL) {
 250                 pr_err("Unable to find fpga-sd\n");
 251                 ret = -ENOENT;
 252                 goto out;
 253         }
 254
 255         fpga = of_iomap(np, 0);
 256         of_node_put(np);
 257         if (fpga == NULL) {
 258                 pr_err("Unable to map fpga-sd\n");
 259                 ret = -ENOMEM;
 260                 goto out;
 261         }
 262
 263         /* -- FPGA: POST Test Results Register 1 (32bit R/W) (Offset: 0x4040) --
 264          * Bit 31,   WDOG: Set to 1 when the last reset was caused by a watchdog
 265          *           timeout.
 266          */
 267         post1 = in_be32(fpga + 0x40);
 268         if (post1 & 0x80000000)
 269                 pikawdt_private.bootstatus = WDIOF_CARDRESET;
 270
 271         iounmap(fpga);
 272
 273         timer_setup(&pikawdt_private.timer, pikawdt_ping, 0);
 274
 275         ret = misc_register(&pikawdt_miscdev);
 276         if (ret) {
 277                 pr_err("Unable to register miscdev\n");
 278                 goto out;
 279         }
 280
 281         pr_info("initialized. heartbeat=%d sec (nowayout=%d)\n",
 282                 heartbeat, nowayout);
 283         return 0;
 284
 285 out:
 286         iounmap(pikawdt_private.fpga);
 287         return ret;
 288 }
 289
 290 static void __exit pikawdt_exit(void)
 291 {
 292         misc_deregister(&pikawdt_miscdev);
 293
 294         iounmap(pikawdt_private.fpga);
 295 }
 296
 297 module_init(pikawdt_init);
 298 module_exit(pikawdt_exit);
 299
 300 MODULE_AUTHOR("Sean MacLennan <smaclennan@pikatech.com>");
 301 MODULE_DESCRIPTION("PIKA FPGA based Watchdog Timer");
 302 MODULE_LICENSE("GPL");