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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  21
  22 #include <linux/bitops.h>
  23 #include <linux/errno.h>
  24 #include <linux/fs.h>
  25 #include <linux/init.h>
  26 #include <linux/kernel.h>
  27 #include <linux/miscdevice.h>
  28 #include <linux/module.h>
  29 #include <linux/moduleparam.h>
  30 #include <linux/platform_device.h>
  31 #include <linux/types.h>
  32 #include <linux/watchdog.h>
  33 #include <linux/clk.h>
  34 #include <linux/err.h>
  35
  36 #include <asm/mach-ath79/ath79.h>
  37 #include <asm/mach-ath79/ar71xx_regs.h>
  38
  39 #define DRIVER_NAME     "ath79-wdt"
  40
  41 #define WDT_TIMEOUT     15      /* seconds */
  42
  43 #define WDOG_CTRL_LAST_RESET    BIT(31)
  44 #define WDOG_CTRL_ACTION_MASK   3
  45 #define WDOG_CTRL_ACTION_NONE   0       /* no action */
  46 #define WDOG_CTRL_ACTION_GPI    1       /* general purpose interrupt */
  47 #define WDOG_CTRL_ACTION_NMI    2       /* NMI */
  48 #define WDOG_CTRL_ACTION_FCR    3       /* full chip reset */
  49
  50 static bool nowayout = WATCHDOG_NOWAYOUT;
  51 module_param(nowayout, bool, 0);
  52 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
  53                            "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  54
  55 static int timeout = WDT_TIMEOUT;
  56 module_param(timeout, int, 0);
  57 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds "
  58                           "(default=" __MODULE_STRING(WDT_TIMEOUT) "s)");
  59
  60 static unsigned long wdt_flags;
  61
  62 #define WDT_FLAGS_BUSY          0
  63 #define WDT_FLAGS_EXPECT_CLOSE  1
  64
  65 static struct clk *wdt_clk;
  66 static unsigned long wdt_freq;
  67 static int boot_status;
  68 static int max_timeout;
  69
  70 static inline void ath79_wdt_keepalive(void)
  71 {
  72         ath79_reset_wr(AR71XX_RESET_REG_WDOG, wdt_freq * timeout);
  73         /* flush write */
  74         ath79_reset_rr(AR71XX_RESET_REG_WDOG);
  75 }
  76
  77 static inline void ath79_wdt_enable(void)
  78 {
  79         ath79_wdt_keepalive();
  80         ath79_reset_wr(AR71XX_RESET_REG_WDOG_CTRL, WDOG_CTRL_ACTION_FCR);
  81         /* flush write */
  82         ath79_reset_rr(AR71XX_RESET_REG_WDOG_CTRL);
  83 }
  84
  85 static inline void ath79_wdt_disable(void)
  86 {
  87         ath79_reset_wr(AR71XX_RESET_REG_WDOG_CTRL, WDOG_CTRL_ACTION_NONE);
  88         /* flush write */
  89         ath79_reset_rr(AR71XX_RESET_REG_WDOG_CTRL);
  90 }
  91
  92 static int ath79_wdt_set_timeout(int val)
  93 {
  94         if (val < 1 || val > max_timeout)
  95                 return -EINVAL;
  96
  97         timeout = val;
  98         ath79_wdt_keepalive();
  99
 100         return 0;
 101 }
 102
 103 static int ath79_wdt_open(struct inode *inode, struct file *file)
 104 {
 105         if (test_and_set_bit(WDT_FLAGS_BUSY, &wdt_flags))
 106                 return -EBUSY;
 107
 108         clear_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags);
 109         ath79_wdt_enable();
 110
 111         return nonseekable_open(inode, file);
 112 }
 113
 114 static int ath79_wdt_release(struct inode *inode, struct file *file)
 115 {
 116         if (test_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags))
 117                 ath79_wdt_disable();
 118         else {
 119                 pr_crit("device closed unexpectedly, watchdog timer will not stop!\n");
 120                 ath79_wdt_keepalive();
 121         }
 122
 123         clear_bit(WDT_FLAGS_BUSY, &wdt_flags);
 124         clear_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags);
 125
 126         return 0;
 127 }
 128
 129 static ssize_t ath79_wdt_write(struct file *file, const char *data,
 130                                 size_t len, loff_t *ppos)
 131 {
 132         if (len) {
 133                 if (!nowayout) {
 134                         size_t i;
 135
 136                         clear_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags);
 137
 138                         for (i = 0; i != len; i++) {
 139                                 char c;
 140
 141                                 if (get_user(c, data + i))
 142                                         return -EFAULT;
 143
 144                                 if (c == 'V')
 145                                         set_bit(WDT_FLAGS_EXPECT_CLOSE,
 146                                                 &wdt_flags);
 147                         }
 148                 }
 149
 150                 ath79_wdt_keepalive();
 151         }
 152
 153         return len;
 154 }
 155
 156 static const struct watchdog_info ath79_wdt_info = {
 157         .options                = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
 158                                   WDIOF_MAGICCLOSE | WDIOF_CARDRESET,
 159         .firmware_version       = 0,
 160         .identity               = "ATH79 watchdog",
 161 };
 162
 163 static long ath79_wdt_ioctl(struct file *file, unsigned int cmd,
 164                             unsigned long arg)
 165 {
 166         void __user *argp = (void __user *)arg;
 167         int __user *p = argp;
 168         int err;
 169         int t;
 170
 171         switch (cmd) {
 172         case WDIOC_GETSUPPORT:
 173                 err = copy_to_user(argp, &ath79_wdt_info,
 174                                    sizeof(ath79_wdt_info)) ? -EFAULT : 0;
 175                 break;
 176
 177         case WDIOC_GETSTATUS:
 178                 err = put_user(0, p);
 179                 break;
 180
 181         case WDIOC_GETBOOTSTATUS:
 182                 err = put_user(boot_status, p);
 183                 break;
 184
 185         case WDIOC_KEEPALIVE:
 186                 ath79_wdt_keepalive();
 187                 err = 0;
 188                 break;
 189
 190         case WDIOC_SETTIMEOUT:
 191                 err = get_user(t, p);
 192                 if (err)
 193                         break;
 194
 195                 err = ath79_wdt_set_timeout(t);
 196                 if (err)
 197                         break;
 198
 199                 /* fallthrough */
 200         case WDIOC_GETTIMEOUT:
 201                 err = put_user(timeout, p);
 202                 break;
 203
 204         default:
 205                 err = -ENOTTY;
 206                 break;
 207         }
 208
 209         return err;
 210 }
 211
 212 static const struct file_operations ath79_wdt_fops = {
 213         .owner          = THIS_MODULE,
 214         .llseek         = no_llseek,
 215         .write          = ath79_wdt_write,
 216         .unlocked_ioctl = ath79_wdt_ioctl,
 217         .open           = ath79_wdt_open,
 218         .release        = ath79_wdt_release,
 219 };
 220
 221 static struct miscdevice ath79_wdt_miscdev = {
 222         .minor = WATCHDOG_MINOR,
 223         .name = "watchdog",
 224         .fops = &ath79_wdt_fops,
 225 };
 226
 227 static int ath79_wdt_probe(struct platform_device *pdev)
 228 {
 229         u32 ctrl;
 230         int err;
 231
 232         wdt_clk = clk_get(&pdev->dev, "wdt");
 233         if (IS_ERR(wdt_clk))
 234                 return PTR_ERR(wdt_clk);
 235
 236         err = clk_enable(wdt_clk);
 237         if (err)
 238                 goto err_clk_put;
 239
 240         wdt_freq = clk_get_rate(wdt_clk);
 241         if (!wdt_freq) {
 242                 err = -EINVAL;
 243                 goto err_clk_disable;
 244         }
 245
 246         max_timeout = (0xfffffffful / wdt_freq);
 247         if (timeout < 1 || timeout > max_timeout) {
 248                 timeout = max_timeout;
 249                 dev_info(&pdev->dev,
 250                         "timeout value must be 0 < timeout < %d, using %d\n",
 251                         max_timeout, timeout);
 252         }
 253
 254         ctrl = ath79_reset_rr(AR71XX_RESET_REG_WDOG_CTRL);
 255         boot_status = (ctrl & WDOG_CTRL_LAST_RESET) ? WDIOF_CARDRESET : 0;
 256
 257         err = misc_register(&ath79_wdt_miscdev);
 258         if (err) {
 259                 dev_err(&pdev->dev,
 260                         "unable to register misc device, err=%d\n", err);
 261                 goto err_clk_disable;
 262         }
 263
 264         return 0;
 265
 266 err_clk_disable:
 267         clk_disable(wdt_clk);
 268 err_clk_put:
 269         clk_put(wdt_clk);
 270         return err;
 271 }
 272
 273 static int ath79_wdt_remove(struct platform_device *pdev)
 274 {
 275         misc_deregister(&ath79_wdt_miscdev);
 276         clk_disable(wdt_clk);
 277         clk_put(wdt_clk);
 278         return 0;
 279 }
 280
 281 static void ath97_wdt_shutdown(struct platform_device *pdev)
 282 {
 283         ath79_wdt_disable();
 284 }
 285
 286 static struct platform_driver ath79_wdt_driver = {
 287         .remove         = ath79_wdt_remove,
 288         .shutdown       = ath97_wdt_shutdown,
 289         .driver         = {
 290                 .name   = DRIVER_NAME,
 291                 .owner  = THIS_MODULE,
 292         },
 293 };
 294
 295 static int __init ath79_wdt_init(void)
 296 {
 297         return platform_driver_probe(&ath79_wdt_driver, ath79_wdt_probe);
 298 }
 299 module_init(ath79_wdt_init);
 300
 301 static void __exit ath79_wdt_exit(void)
 302 {
 303         platform_driver_unregister(&ath79_wdt_driver);
 304 }
 305 module_exit(ath79_wdt_exit);
 306
 307 MODULE_DESCRIPTION("Atheros AR71XX/AR724X/AR913X hardware watchdog driver");
 308 MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org");
 309 MODULE_AUTHOR("Imre Kaloz <kaloz@openwrt.org");
 310 MODULE_LICENSE("GPL v2");
 311 MODULE_ALIAS("platform:" DRIVER_NAME);
 312 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);