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/delay.h>
  22 #include <linux/errno.h>
  23 #include <linux/fs.h>
  24 #include <linux/init.h>
  25 #include <linux/kernel.h>
  26 #include <linux/miscdevice.h>
  27 #include <linux/module.h>
  28 #include <linux/moduleparam.h>
  29 #include <linux/platform_device.h>
  30 #include <linux/types.h>
  31 #include <linux/watchdog.h>
  32 #include <linux/clk.h>
  33 #include <linux/err.h>
  34
  35 #include <asm/mach-ath79/ath79.h>
  36 #include <asm/mach-ath79/ar71xx_regs.h>
  37
  38 #define DRIVER_NAME     "ath79-wdt"
  39
  40 #define WDT_TIMEOUT     15      /* seconds */
  41
  42 #define WDOG_CTRL_LAST_RESET    BIT(31)
  43 #define WDOG_CTRL_ACTION_MASK   3
  44 #define WDOG_CTRL_ACTION_NONE   0       /* no action */
  45 #define WDOG_CTRL_ACTION_GPI    1       /* general purpose interrupt */
  46 #define WDOG_CTRL_ACTION_NMI    2       /* NMI */
  47 #define WDOG_CTRL_ACTION_FCR    3       /* full chip reset */
  48
  49 static int nowayout = WATCHDOG_NOWAYOUT;
  50 module_param(nowayout, int, 0);
  51 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
  52                            "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  53
  54 static int timeout = WDT_TIMEOUT;
  55 module_param(timeout, int, 0);
  56 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds "
  57                           "(default=" __MODULE_STRING(WDT_TIMEOUT) "s)");
  58
  59 static unsigned long wdt_flags;
  60
  61 #define WDT_FLAGS_BUSY          0
  62 #define WDT_FLAGS_EXPECT_CLOSE  1
  63
  64 static struct clk *wdt_clk;
  65 static unsigned long wdt_freq;
  66 static int boot_status;
  67 static int max_timeout;
  68
  69 static inline void ath79_wdt_keepalive(void)
  70 {
  71         ath79_reset_wr(AR71XX_RESET_REG_WDOG, wdt_freq * timeout);
  72 }
  73
  74 static inline void ath79_wdt_enable(void)
  75 {
  76         ath79_wdt_keepalive();
  77
  78         /*
  79          * Updating the TIMER register requires a few microseconds
  80          * on the AR934x SoCs at least. Use a small delay to ensure
  81          * that the TIMER register is updated within the hardware
  82          * before enabling the watchdog.
  83          */
  84         udelay(2);
  85
  86         ath79_reset_wr(AR71XX_RESET_REG_WDOG_CTRL, WDOG_CTRL_ACTION_FCR);
  87 }
  88
  89 static inline void ath79_wdt_disable(void)
  90 {
  91         ath79_reset_wr(AR71XX_RESET_REG_WDOG_CTRL, WDOG_CTRL_ACTION_NONE);
  92 }
  93
  94 static int ath79_wdt_set_timeout(int val)
  95 {
  96         if (val < 1 || val > max_timeout)
  97                 return -EINVAL;
  98
  99         timeout = val;
 100         ath79_wdt_keepalive();
 101
 102         return 0;
 103 }
 104
 105 static int ath79_wdt_open(struct inode *inode, struct file *file)
 106 {
 107         if (test_and_set_bit(WDT_FLAGS_BUSY, &wdt_flags))
 108                 return -EBUSY;
 109
 110         clear_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags);
 111         ath79_wdt_enable();
 112
 113         return nonseekable_open(inode, file);
 114 }
 115
 116 static int ath79_wdt_release(struct inode *inode, struct file *file)
 117 {
 118         if (test_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags))
 119                 ath79_wdt_disable();
 120         else {
 121                 pr_crit(DRIVER_NAME ": device closed unexpectedly, "
 122                         "watchdog timer will not stop!\n");
 123                 ath79_wdt_keepalive();
 124         }
 125
 126         clear_bit(WDT_FLAGS_BUSY, &wdt_flags);
 127         clear_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags);
 128
 129         return 0;
 130 }
 131
 132 static ssize_t ath79_wdt_write(struct file *file, const char *data,
 133                                 size_t len, loff_t *ppos)
 134 {
 135         if (len) {
 136                 if (!nowayout) {
 137                         size_t i;
 138
 139                         clear_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags);
 140
 141                         for (i = 0; i != len; i++) {
 142                                 char c;
 143
 144                                 if (get_user(c, data + i))
 145                                         return -EFAULT;
 146
 147                                 if (c == 'V')
 148                                         set_bit(WDT_FLAGS_EXPECT_CLOSE,
 149                                                 &wdt_flags);
 150                         }
 151                 }
 152
 153                 ath79_wdt_keepalive();
 154         }
 155
 156         return len;
 157 }
 158
 159 static const struct watchdog_info ath79_wdt_info = {
 160         .options                = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
 161                                   WDIOF_MAGICCLOSE | WDIOF_CARDRESET,
 162         .firmware_version       = 0,
 163         .identity               = "ATH79 watchdog",
 164 };
 165
 166 static long ath79_wdt_ioctl(struct file *file, unsigned int cmd,
 167                             unsigned long arg)
 168 {
 169         void __user *argp = (void __user *)arg;
 170         int __user *p = argp;
 171         int err;
 172         int t;
 173
 174         switch (cmd) {
 175         case WDIOC_GETSUPPORT:
 176                 err = copy_to_user(argp, &ath79_wdt_info,
 177                                    sizeof(ath79_wdt_info)) ? -EFAULT : 0;
 178                 break;
 179
 180         case WDIOC_GETSTATUS:
 181                 err = put_user(0, p);
 182                 break;
 183
 184         case WDIOC_GETBOOTSTATUS:
 185                 err = put_user(boot_status, p);
 186                 break;
 187
 188         case WDIOC_KEEPALIVE:
 189                 ath79_wdt_keepalive();
 190                 err = 0;
 191                 break;
 192
 193         case WDIOC_SETTIMEOUT:
 194                 err = get_user(t, p);
 195                 if (err)
 196                         break;
 197
 198                 err = ath79_wdt_set_timeout(t);
 199                 if (err)
 200                         break;
 201
 202                 /* fallthrough */
 203         case WDIOC_GETTIMEOUT:
 204                 err = put_user(timeout, p);
 205                 break;
 206
 207         default:
 208                 err = -ENOTTY;
 209                 break;
 210         }
 211
 212         return err;
 213 }
 214
 215 static const struct file_operations ath79_wdt_fops = {
 216         .owner          = THIS_MODULE,
 217         .llseek         = no_llseek,
 218         .write          = ath79_wdt_write,
 219         .unlocked_ioctl = ath79_wdt_ioctl,
 220         .open           = ath79_wdt_open,
 221         .release        = ath79_wdt_release,
 222 };
 223
 224 static struct miscdevice ath79_wdt_miscdev = {
 225         .minor = WATCHDOG_MINOR,
 226         .name = "watchdog",
 227         .fops = &ath79_wdt_fops,
 228 };
 229
 230 static int __devinit ath79_wdt_probe(struct platform_device *pdev)
 231 {
 232         u32 ctrl;
 233         int err;
 234
 235         wdt_clk = clk_get(&pdev->dev, "wdt");
 236         if (IS_ERR(wdt_clk))
 237                 return PTR_ERR(wdt_clk);
 238
 239         err = clk_enable(wdt_clk);
 240         if (err)
 241                 goto err_clk_put;
 242
 243         wdt_freq = clk_get_rate(wdt_clk);
 244         if (!wdt_freq) {
 245                 err = -EINVAL;
 246                 goto err_clk_disable;
 247         }
 248
 249         max_timeout = (0xfffffffful / wdt_freq);
 250         if (timeout < 1 || timeout > max_timeout) {
 251                 timeout = max_timeout;
 252                 dev_info(&pdev->dev,
 253                         "timeout value must be 0 < timeout < %d, using %d\n",
 254                         max_timeout, timeout);
 255         }
 256
 257         ctrl = ath79_reset_rr(AR71XX_RESET_REG_WDOG_CTRL);
 258         boot_status = (ctrl & WDOG_CTRL_LAST_RESET) ? WDIOF_CARDRESET : 0;
 259
 260         err = misc_register(&ath79_wdt_miscdev);
 261         if (err) {
 262                 dev_err(&pdev->dev,
 263                         "unable to register misc device, err=%d\n", err);
 264                 goto err_clk_disable;
 265         }
 266
 267         return 0;
 268
 269 err_clk_disable:
 270         clk_disable(wdt_clk);
 271 err_clk_put:
 272         clk_put(wdt_clk);
 273         return err;
 274 }
 275
 276 static int __devexit ath79_wdt_remove(struct platform_device *pdev)
 277 {
 278         misc_deregister(&ath79_wdt_miscdev);
 279         clk_disable(wdt_clk);
 280         clk_put(wdt_clk);
 281         return 0;
 282 }
 283
 284 static void ath97_wdt_shutdown(struct platform_device *pdev)
 285 {
 286         ath79_wdt_disable();
 287 }
 288
 289 static struct platform_driver ath79_wdt_driver = {
 290         .remove         = __devexit_p(ath79_wdt_remove),
 291         .shutdown       = ath97_wdt_shutdown,
 292         .driver         = {
 293                 .name   = DRIVER_NAME,
 294                 .owner  = THIS_MODULE,
 295         },
 296 };
 297
 298 static int __init ath79_wdt_init(void)
 299 {
 300         return platform_driver_probe(&ath79_wdt_driver, ath79_wdt_probe);
 301 }
 302 module_init(ath79_wdt_init);
 303
 304 static void __exit ath79_wdt_exit(void)
 305 {
 306         platform_driver_unregister(&ath79_wdt_driver);
 307 }
 308 module_exit(ath79_wdt_exit);
 309
 310 MODULE_DESCRIPTION("Atheros AR71XX/AR724X/AR913X hardware watchdog driver");
 311 MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org");
 312 MODULE_AUTHOR("Imre Kaloz <kaloz@openwrt.org");
 313 MODULE_LICENSE("GPL v2");
 314 MODULE_ALIAS("platform:" DRIVER_NAME);
 315 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);