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         /* flush write */
  72         ath79_reset_rr(AR71XX_RESET_REG_WDOG);
  73 }
  74
  75 static inline void ath79_wdt_enable(void)
  76 {
  77         ath79_wdt_keepalive();
  78         ath79_reset_wr(AR71XX_RESET_REG_WDOG_CTRL, WDOG_CTRL_ACTION_FCR);
  79         /* flush write */
  80         ath79_reset_rr(AR71XX_RESET_REG_WDOG_CTRL);
  81 }
  82
  83 static inline void ath79_wdt_disable(void)
  84 {
  85         ath79_reset_wr(AR71XX_RESET_REG_WDOG_CTRL, WDOG_CTRL_ACTION_NONE);
  86         /* flush write */
  87         ath79_reset_rr(AR71XX_RESET_REG_WDOG_CTRL);
  88 }
  89
  90 static int ath79_wdt_set_timeout(int val)
  91 {
  92         if (val < 1 || val > max_timeout)
  93                 return -EINVAL;
  94
  95         timeout = val;
  96         ath79_wdt_keepalive();
  97
  98         return 0;
  99 }
 100
 101 static int ath79_wdt_open(struct inode *inode, struct file *file)
 102 {
 103         if (test_and_set_bit(WDT_FLAGS_BUSY, &wdt_flags))
 104                 return -EBUSY;
 105
 106         clear_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags);
 107         ath79_wdt_enable();
 108
 109         return nonseekable_open(inode, file);
 110 }
 111
 112 static int ath79_wdt_release(struct inode *inode, struct file *file)
 113 {
 114         if (test_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags))
 115                 ath79_wdt_disable();
 116         else {
 117                 pr_crit(DRIVER_NAME ": device closed unexpectedly, "
 118                         "watchdog timer will not stop!\n");
 119                 ath79_wdt_keepalive();
 120         }
 121
 122         clear_bit(WDT_FLAGS_BUSY, &wdt_flags);
 123         clear_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags);
 124
 125         return 0;
 126 }
 127
 128 static ssize_t ath79_wdt_write(struct file *file, const char *data,
 129                                 size_t len, loff_t *ppos)
 130 {
 131         if (len) {
 132                 if (!nowayout) {
 133                         size_t i;
 134
 135                         clear_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags);
 136
 137                         for (i = 0; i != len; i++) {
 138                                 char c;
 139
 140                                 if (get_user(c, data + i))
 141                                         return -EFAULT;
 142
 143                                 if (c == 'V')
 144                                         set_bit(WDT_FLAGS_EXPECT_CLOSE,
 145                                                 &wdt_flags);
 146                         }
 147                 }
 148
 149                 ath79_wdt_keepalive();
 150         }
 151
 152         return len;
 153 }
 154
 155 static const struct watchdog_info ath79_wdt_info = {
 156         .options                = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
 157                                   WDIOF_MAGICCLOSE | WDIOF_CARDRESET,
 158         .firmware_version       = 0,
 159         .identity               = "ATH79 watchdog",
 160 };
 161
 162 static long ath79_wdt_ioctl(struct file *file, unsigned int cmd,
 163                             unsigned long arg)
 164 {
 165         void __user *argp = (void __user *)arg;
 166         int __user *p = argp;
 167         int err;
 168         int t;
 169
 170         switch (cmd) {
 171         case WDIOC_GETSUPPORT:
 172                 err = copy_to_user(argp, &ath79_wdt_info,
 173                                    sizeof(ath79_wdt_info)) ? -EFAULT : 0;
 174                 break;
 175
 176         case WDIOC_GETSTATUS:
 177                 err = put_user(0, p);
 178                 break;
 179
 180         case WDIOC_GETBOOTSTATUS:
 181                 err = put_user(boot_status, p);
 182                 break;
 183
 184         case WDIOC_KEEPALIVE:
 185                 ath79_wdt_keepalive();
 186                 err = 0;
 187                 break;
 188
 189         case WDIOC_SETTIMEOUT:
 190                 err = get_user(t, p);
 191                 if (err)
 192                         break;
 193
 194                 err = ath79_wdt_set_timeout(t);
 195                 if (err)
 196                         break;
 197
 198                 /* fallthrough */
 199         case WDIOC_GETTIMEOUT:
 200                 err = put_user(timeout, p);
 201                 break;
 202
 203         default:
 204                 err = -ENOTTY;
 205                 break;
 206         }
 207
 208         return err;
 209 }
 210
 211 static const struct file_operations ath79_wdt_fops = {
 212         .owner          = THIS_MODULE,
 213         .llseek         = no_llseek,
 214         .write          = ath79_wdt_write,
 215         .unlocked_ioctl = ath79_wdt_ioctl,
 216         .open           = ath79_wdt_open,
 217         .release        = ath79_wdt_release,
 218 };
 219
 220 static struct miscdevice ath79_wdt_miscdev = {
 221         .minor = WATCHDOG_MINOR,
 222         .name = "watchdog",
 223         .fops = &ath79_wdt_fops,
 224 };
 225
 226 static int __devinit ath79_wdt_probe(struct platform_device *pdev)
 227 {
 228         u32 ctrl;
 229         int err;
 230
 231         wdt_clk = clk_get(&pdev->dev, "wdt");
 232         if (IS_ERR(wdt_clk))
 233                 return PTR_ERR(wdt_clk);
 234
 235         err = clk_enable(wdt_clk);
 236         if (err)
 237                 goto err_clk_put;
 238
 239         wdt_freq = clk_get_rate(wdt_clk);
 240         if (!wdt_freq) {
 241                 err = -EINVAL;
 242                 goto err_clk_disable;
 243         }
 244
 245         max_timeout = (0xfffffffful / wdt_freq);
 246         if (timeout < 1 || timeout > max_timeout) {
 247                 timeout = max_timeout;
 248                 dev_info(&pdev->dev,
 249                         "timeout value must be 0 < timeout < %d, using %d\n",
 250                         max_timeout, timeout);
 251         }
 252
 253         ctrl = ath79_reset_rr(AR71XX_RESET_REG_WDOG_CTRL);
 254         boot_status = (ctrl & WDOG_CTRL_LAST_RESET) ? WDIOF_CARDRESET : 0;
 255
 256         err = misc_register(&ath79_wdt_miscdev);
 257         if (err) {
 258                 dev_err(&pdev->dev,
 259                         "unable to register misc device, err=%d\n", err);
 260                 goto err_clk_disable;
 261         }
 262
 263         return 0;
 264
 265 err_clk_disable:
 266         clk_disable(wdt_clk);
 267 err_clk_put:
 268         clk_put(wdt_clk);
 269         return err;
 270 }
 271
 272 static int __devexit ath79_wdt_remove(struct platform_device *pdev)
 273 {
 274         misc_deregister(&ath79_wdt_miscdev);
 275         clk_disable(wdt_clk);
 276         clk_put(wdt_clk);
 277         return 0;
 278 }
 279
 280 static void ath97_wdt_shutdown(struct platform_device *pdev)
 281 {
 282         ath79_wdt_disable();
 283 }
 284
 285 static struct platform_driver ath79_wdt_driver = {
 286         .remove         = __devexit_p(ath79_wdt_remove),
 287         .shutdown       = ath97_wdt_shutdown,
 288         .driver         = {
 289                 .name   = DRIVER_NAME,
 290                 .owner  = THIS_MODULE,
 291         },
 292 };
 293
 294 static int __init ath79_wdt_init(void)
 295 {
 296         return platform_driver_probe(&ath79_wdt_driver, ath79_wdt_probe);
 297 }
 298 module_init(ath79_wdt_init);
 299
 300 static void __exit ath79_wdt_exit(void)
 301 {
 302         platform_driver_unregister(&ath79_wdt_driver);
 303 }
 304 module_exit(ath79_wdt_exit);
 305
 306 MODULE_DESCRIPTION("Atheros AR71XX/AR724X/AR913X hardware watchdog driver");
 307 MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org");
 308 MODULE_AUTHOR("Imre Kaloz <kaloz@openwrt.org");
 309 MODULE_LICENSE("GPL v2");
 310 MODULE_ALIAS("platform:" DRIVER_NAME);
 311 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);