linux/drivers/watchdog/pika_wdt.c
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   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
  38static int heartbeat = WDT_HEARTBEAT;
  39module_param(heartbeat, int, 0);
  40MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. "
  41        "(default = " __MODULE_STRING(WDT_HEARTBEAT) ")");
  42
  43static bool nowayout = WATCHDOG_NOWAYOUT;
  44module_param(nowayout, bool, 0);
  45MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
  46        "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  47
  48static 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
  57static 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 */
  68static 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 */
  88static void pikawdt_ping(unsigned long data)
  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
  99static void pikawdt_keepalive(void)
 100{
 101        pikawdt_private.next_heartbeat = jiffies + heartbeat * HZ;
 102}
 103
 104static 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 */
 113static 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 */
 127static 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 */
 141static 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 */
 172static 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
 209static 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
 218static struct miscdevice pikawdt_miscdev = {
 219        .minor  = WATCHDOG_MINOR,
 220        .name   = "watchdog",
 221        .fops   = &pikawdt_fops,
 222};
 223
 224static 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        setup_timer(&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
 284out:
 285        iounmap(pikawdt_private.fpga);
 286        return ret;
 287}
 288
 289static void __exit pikawdt_exit(void)
 290{
 291        misc_deregister(&pikawdt_miscdev);
 292
 293        iounmap(pikawdt_private.fpga);
 294}
 295
 296module_init(pikawdt_init);
 297module_exit(pikawdt_exit);
 298
 299MODULE_AUTHOR("Sean MacLennan <smaclennan@pikatech.com>");
 300MODULE_DESCRIPTION("PIKA FPGA based Watchdog Timer");
 301MODULE_LICENSE("GPL");
 302