drivers/watchdog/ath79_wdt.c

   1 /*
   2  * Atheros AR71XX/AR724X/AR913X built-in hardware watchdog timer.
   3  *
   4  * Copyright (C) 2008-2011 Gabor Juhos <juhosg@openwrt.org>
   5  * Copyright (C) 2008 Imre Kaloz <kaloz@openwrt.org>
   6  *
   7  * This driver was based on: drivers/watchdog/ixp4xx_wdt.c
   8  *      Author: Deepak Saxena <dsaxena@plexity.net>
   9  *      Copyright 2004 (c) MontaVista, Software, Inc.
  10  *
  11  * which again was based on sa1100 driver,
  12  *      Copyright (C) 2000 Oleg Drokin <green@crimea.edu>
  13  *
  14  * This program is free software; you can redistribute it and/or modify it
  15  * under the terms of the GNU General Public License version 2 as published
  16  * by the Free Software Foundation.
  17  *
  18  */
  19
  20 #include <linux/bitops.h>
  21 #include <linux/errno.h>
  22 #include <linux/fs.h>
  23 #include <linux/init.h>
  24 #include <linux/kernel.h>
  25 #include <linux/miscdevice.h>
  26 #include <linux/module.h>
  27 #include <linux/moduleparam.h>
  28 #include <linux/platform_device.h>
  29 #include <linux/types.h>
  30 #include <linux/watchdog.h>
  31 #include <linux/clk.h>
  32 #include <linux/err.h>
  33
  34 #include <asm/mach-ath79/ath79.h>
  35 #include <asm/mach-ath79/ar71xx_regs.h>
  36
  37 #define DRIVER_NAME     "ath79-wdt"
  38
  39 #define WDT_TIMEOUT     15      /* seconds */
  40
  41 #define WDOG_CTRL_LAST_RESET    BIT(31)
  42 #define WDOG_CTRL_ACTION_MASK   3
  43 #define WDOG_CTRL_ACTION_NONE   0       /* no action */
  44 #define WDOG_CTRL_ACTION_GPI    1       /* general purpose interrupt */
  45 #define WDOG_CTRL_ACTION_NMI    2       /* NMI */
  46 #define WDOG_CTRL_ACTION_FCR    3       /* full chip reset */
  47
  48 static int nowayout = WATCHDOG_NOWAYOUT;
  49 module_param(nowayout, int, 0);
  50 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
  51                            "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  52
  53 static int timeout = WDT_TIMEOUT;
  54 module_param(timeout, int, 0);
  55 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds "
  56                           "(default=" __MODULE_STRING(WDT_TIMEOUT) "s)");
  57
  58 static unsigned long wdt_flags;
  59
  60 #define WDT_FLAGS_BUSY          0
  61 #define WDT_FLAGS_EXPECT_CLOSE  1
  62
  63 static struct clk *wdt_clk;
  64 static unsigned long wdt_freq;
  65 static int boot_status;
  66 static int max_timeout;
  67
  68 static inline void ath79_wdt_keepalive(void)
  69 {
  70         ath79_reset_wr(AR71XX_RESET_REG_WDOG, wdt_freq * timeout);
  71 }
  72
  73 static inline void ath79_wdt_enable(void)
  74 {
  75         ath79_wdt_keepalive();
  76         ath79_reset_wr(AR71XX_RESET_REG_WDOG_CTRL, WDOG_CTRL_ACTION_FCR);
  77 }
  78
  79 static inline void ath79_wdt_disable(void)
  80 {
  81         ath79_reset_wr(AR71XX_RESET_REG_WDOG_CTRL, WDOG_CTRL_ACTION_NONE);
  82 }
  83
  84 static int ath79_wdt_set_timeout(int val)
  85 {
  86         if (val < 1 || val > max_timeout)
  87                 return -EINVAL;
  88
  89         timeout = val;
  90         ath79_wdt_keepalive();
  91
  92         return 0;
  93 }
  94
  95 static int ath79_wdt_open(struct inode *inode, struct file *file)
  96 {
  97         if (test_and_set_bit(WDT_FLAGS_BUSY, &wdt_flags))
  98                 return -EBUSY;
  99
 100         clear_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags);
 101         ath79_wdt_enable();
 102
 103         return nonseekable_open(inode, file);
 104 }
 105
 106 static int ath79_wdt_release(struct inode *inode, struct file *file)
 107 {
 108         if (test_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags))
 109                 ath79_wdt_disable();
 110         else {
 111                 pr_crit(DRIVER_NAME ": device closed unexpectedly, "
 112                         "watchdog timer will not stop!\n");
 113                 ath79_wdt_keepalive();
 114         }
 115
 116         clear_bit(WDT_FLAGS_BUSY, &wdt_flags);
 117         clear_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags);
 118
 119         return 0;
 120 }
 121
 122 static ssize_t ath79_wdt_write(struct file *file, const char *data,
 123                                 size_t len, loff_t *ppos)
 124 {
 125         if (len) {
 126                 if (!nowayout) {
 127                         size_t i;
 128
 129                         clear_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags);
 130
 131                         for (i = 0; i != len; i++) {
 132                                 char c;
 133
 134                                 if (get_user(c, data + i))
 135                                         return -EFAULT;
 136
 137                                 if (c == 'V')
 138                                         set_bit(WDT_FLAGS_EXPECT_CLOSE,
 139                                                 &wdt_flags);
 140                         }
 141                 }
 142
 143                 ath79_wdt_keepalive();
 144         }
 145
 146         return len;
 147 }
 148
 149 static const struct watchdog_info ath79_wdt_info = {
 150         .options                = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
 151                                   WDIOF_MAGICCLOSE | WDIOF_CARDRESET,
 152         .firmware_version       = 0,
 153         .identity               = "ATH79 watchdog",
 154 };
 155
 156 static long ath79_wdt_ioctl(struct file *file, unsigned int cmd,
 157                             unsigned long arg)
 158 {
 159         void __user *argp = (void __user *)arg;
 160         int __user *p = argp;
 161         int err;
 162         int t;
 163
 164         switch (cmd) {
 165         case WDIOC_GETSUPPORT:
 166                 err = copy_to_user(argp, &ath79_wdt_info,
 167                                    sizeof(ath79_wdt_info)) ? -EFAULT : 0;
 168                 break;
 169
 170         case WDIOC_GETSTATUS:
 171                 err = put_user(0, p);
 172                 break;
 173
 174         case WDIOC_GETBOOTSTATUS:
 175                 err = put_user(boot_status, p);
 176                 break;
 177
 178         case WDIOC_KEEPALIVE:
 179                 ath79_wdt_keepalive();
 180                 err = 0;
 181                 break;
 182
 183         case WDIOC_SETTIMEOUT:
 184                 err = get_user(t, p);
 185                 if (err)
 186                         break;
 187
 188                 err = ath79_wdt_set_timeout(t);
 189                 if (err)
 190                         break;
 191
 192                 /* fallthrough */
 193         case WDIOC_GETTIMEOUT:
 194                 err = put_user(timeout, p);
 195                 break;
 196
 197         default:
 198                 err = -ENOTTY;
 199                 break;
 200         }
 201
 202         return err;
 203 }
 204
 205 static const struct file_operations ath79_wdt_fops = {
 206         .owner          = THIS_MODULE,
 207         .llseek         = no_llseek,
 208         .write          = ath79_wdt_write,
 209         .unlocked_ioctl = ath79_wdt_ioctl,
 210         .open           = ath79_wdt_open,
 211         .release        = ath79_wdt_release,
 212 };
 213
 214 static struct miscdevice ath79_wdt_miscdev = {
 215         .minor = WATCHDOG_MINOR,
 216         .name = "watchdog",
 217         .fops = &ath79_wdt_fops,
 218 };
 219
 220 static int __devinit ath79_wdt_probe(struct platform_device *pdev)
 221 {
 222         u32 ctrl;
 223         int err;
 224
 225         wdt_clk = clk_get(&pdev->dev, "wdt");
 226         if (IS_ERR(wdt_clk))
 227                 return PTR_ERR(wdt_clk);
 228
 229         err = clk_enable(wdt_clk);
 230         if (err)
 231                 goto err_clk_put;
 232
 233         wdt_freq = clk_get_rate(wdt_clk);
 234         if (!wdt_freq) {
 235                 err = -EINVAL;
 236                 goto err_clk_disable;
 237         }
 238
 239         max_timeout = (0xfffffffful / wdt_freq);
 240         if (timeout < 1 || timeout > max_timeout) {
 241                 timeout = max_timeout;
 242                 dev_info(&pdev->dev,
 243                         "timeout value must be 0 < timeout < %d, using %d\n",
 244                         max_timeout, timeout);
 245         }
 246
 247         ctrl = ath79_reset_rr(AR71XX_RESET_REG_WDOG_CTRL);
 248         boot_status = (ctrl & WDOG_CTRL_LAST_RESET) ? WDIOF_CARDRESET : 0;
 249
 250         err = misc_register(&ath79_wdt_miscdev);
 251         if (err) {
 252                 dev_err(&pdev->dev,
 253                         "unable to register misc device, err=%d\n", err);
 254                 goto err_clk_disable;
 255         }
 256
 257         return 0;
 258
 259 err_clk_disable:
 260         clk_disable(wdt_clk);
 261 err_clk_put:
 262         clk_put(wdt_clk);
 263         return err;
 264 }
 265
 266 static int __devexit ath79_wdt_remove(struct platform_device *pdev)
 267 {
 268         misc_deregister(&ath79_wdt_miscdev);
 269         clk_disable(wdt_clk);
 270         clk_put(wdt_clk);
 271         return 0;
 272 }
 273
 274 static void ath97_wdt_shutdown(struct platform_device *pdev)
 275 {
 276         ath79_wdt_disable();
 277 }
 278
 279 static struct platform_driver ath79_wdt_driver = {
 280         .remove         = __devexit_p(ath79_wdt_remove),
 281         .shutdown       = ath97_wdt_shutdown,
 282         .driver         = {
 283                 .name   = DRIVER_NAME,
 284                 .owner  = THIS_MODULE,
 285         },
 286 };
 287
 288 static int __init ath79_wdt_init(void)
 289 {
 290         return platform_driver_probe(&ath79_wdt_driver, ath79_wdt_probe);
 291 }
 292 module_init(ath79_wdt_init);
 293
 294 static void __exit ath79_wdt_exit(void)
 295 {
 296         platform_driver_unregister(&ath79_wdt_driver);
 297 }
 298 module_exit(ath79_wdt_exit);
 299
 300 MODULE_DESCRIPTION("Atheros AR71XX/AR724X/AR913X hardware watchdog driver");
 301 MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org");
 302 MODULE_AUTHOR("Imre Kaloz <kaloz@openwrt.org");
 303 MODULE_LICENSE("GPL v2");
 304 MODULE_ALIAS("platform:" DRIVER_NAME);
 305 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);