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/io.h>
  27 #include <linux/kernel.h>
  28 #include <linux/miscdevice.h>
  29 #include <linux/module.h>
  30 #include <linux/moduleparam.h>
  31 #include <linux/platform_device.h>
  32 #include <linux/types.h>
  33 #include <linux/watchdog.h>
  34 #include <linux/clk.h>
  35 #include <linux/err.h>
  36 #include <linux/of.h>
  37 #include <linux/of_platform.h>
  38
  39 #define DRIVER_NAME     "ath79-wdt"
  40
  41 #define WDT_TIMEOUT     15      /* seconds */
  42
  43 #define WDOG_REG_CTRL           0x00
  44 #define WDOG_REG_TIMER          0x04
  45
  46 #define WDOG_CTRL_LAST_RESET    BIT(31)
  47 #define WDOG_CTRL_ACTION_MASK   3
  48 #define WDOG_CTRL_ACTION_NONE   0       /* no action */
  49 #define WDOG_CTRL_ACTION_GPI    1       /* general purpose interrupt */
  50 #define WDOG_CTRL_ACTION_NMI    2       /* NMI */
  51 #define WDOG_CTRL_ACTION_FCR    3       /* full chip reset */
  52
  53 static bool nowayout = WATCHDOG_NOWAYOUT;
  54 module_param(nowayout, bool, 0);
  55 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
  56                            "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  57
  58 static int timeout = WDT_TIMEOUT;
  59 module_param(timeout, int, 0);
  60 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds "
  61                           "(default=" __MODULE_STRING(WDT_TIMEOUT) "s)");
  62
  63 static unsigned long wdt_flags;
  64
  65 #define WDT_FLAGS_BUSY          0
  66 #define WDT_FLAGS_EXPECT_CLOSE  1
  67
  68 static struct clk *wdt_clk;
  69 static unsigned long wdt_freq;
  70 static int boot_status;
  71 static int max_timeout;
  72 static void __iomem *wdt_base;
  73
  74 static inline void ath79_wdt_wr(unsigned reg, u32 val)
  75 {
  76         iowrite32(val, wdt_base + reg);
  77 }
  78
  79 static inline u32 ath79_wdt_rr(unsigned reg)
  80 {
  81         return ioread32(wdt_base + reg);
  82 }
  83
  84 static inline void ath79_wdt_keepalive(void)
  85 {
  86         ath79_wdt_wr(WDOG_REG_TIMER, wdt_freq * timeout);
  87         /* flush write */
  88         ath79_wdt_rr(WDOG_REG_TIMER);
  89 }
  90
  91 static inline void ath79_wdt_enable(void)
  92 {
  93         ath79_wdt_keepalive();
  94         ath79_wdt_wr(WDOG_REG_CTRL, WDOG_CTRL_ACTION_FCR);
  95         /* flush write */
  96         ath79_wdt_rr(WDOG_REG_CTRL);
  97 }
  98
  99 static inline void ath79_wdt_disable(void)
 100 {
 101         ath79_wdt_wr(WDOG_REG_CTRL, WDOG_CTRL_ACTION_NONE);
 102         /* flush write */
 103         ath79_wdt_rr(WDOG_REG_CTRL);
 104 }
 105
 106 static int ath79_wdt_set_timeout(int val)
 107 {
 108         if (val < 1 || val > max_timeout)
 109                 return -EINVAL;
 110
 111         timeout = val;
 112         ath79_wdt_keepalive();
 113
 114         return 0;
 115 }
 116
 117 static int ath79_wdt_open(struct inode *inode, struct file *file)
 118 {
 119         if (test_and_set_bit(WDT_FLAGS_BUSY, &wdt_flags))
 120                 return -EBUSY;
 121
 122         clear_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags);
 123         ath79_wdt_enable();
 124
 125         return nonseekable_open(inode, file);
 126 }
 127
 128 static int ath79_wdt_release(struct inode *inode, struct file *file)
 129 {
 130         if (test_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags))
 131                 ath79_wdt_disable();
 132         else {
 133                 pr_crit("device closed unexpectedly, watchdog timer will not stop!\n");
 134                 ath79_wdt_keepalive();
 135         }
 136
 137         clear_bit(WDT_FLAGS_BUSY, &wdt_flags);
 138         clear_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags);
 139
 140         return 0;
 141 }
 142
 143 static ssize_t ath79_wdt_write(struct file *file, const char *data,
 144                                 size_t len, loff_t *ppos)
 145 {
 146         if (len) {
 147                 if (!nowayout) {
 148                         size_t i;
 149
 150                         clear_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags);
 151
 152                         for (i = 0; i != len; i++) {
 153                                 char c;
 154
 155                                 if (get_user(c, data + i))
 156                                         return -EFAULT;
 157
 158                                 if (c == 'V')
 159                                         set_bit(WDT_FLAGS_EXPECT_CLOSE,
 160                                                 &wdt_flags);
 161                         }
 162                 }
 163
 164                 ath79_wdt_keepalive();
 165         }
 166
 167         return len;
 168 }
 169
 170 static const struct watchdog_info ath79_wdt_info = {
 171         .options                = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
 172                                   WDIOF_MAGICCLOSE | WDIOF_CARDRESET,
 173         .firmware_version       = 0,
 174         .identity               = "ATH79 watchdog",
 175 };
 176
 177 static long ath79_wdt_ioctl(struct file *file, unsigned int cmd,
 178                             unsigned long arg)
 179 {
 180         void __user *argp = (void __user *)arg;
 181         int __user *p = argp;
 182         int err;
 183         int t;
 184
 185         switch (cmd) {
 186         case WDIOC_GETSUPPORT:
 187                 err = copy_to_user(argp, &ath79_wdt_info,
 188                                    sizeof(ath79_wdt_info)) ? -EFAULT : 0;
 189                 break;
 190
 191         case WDIOC_GETSTATUS:
 192                 err = put_user(0, p);
 193                 break;
 194
 195         case WDIOC_GETBOOTSTATUS:
 196                 err = put_user(boot_status, p);
 197                 break;
 198
 199         case WDIOC_KEEPALIVE:
 200                 ath79_wdt_keepalive();
 201                 err = 0;
 202                 break;
 203
 204         case WDIOC_SETTIMEOUT:
 205                 err = get_user(t, p);
 206                 if (err)
 207                         break;
 208
 209                 err = ath79_wdt_set_timeout(t);
 210                 if (err)
 211                         break;
 212
 213                 /* fallthrough */
 214         case WDIOC_GETTIMEOUT:
 215                 err = put_user(timeout, p);
 216                 break;
 217
 218         default:
 219                 err = -ENOTTY;
 220                 break;
 221         }
 222
 223         return err;
 224 }
 225
 226 static const struct file_operations ath79_wdt_fops = {
 227         .owner          = THIS_MODULE,
 228         .llseek         = no_llseek,
 229         .write          = ath79_wdt_write,
 230         .unlocked_ioctl = ath79_wdt_ioctl,
 231         .open           = ath79_wdt_open,
 232         .release        = ath79_wdt_release,
 233 };
 234
 235 static struct miscdevice ath79_wdt_miscdev = {
 236         .minor = WATCHDOG_MINOR,
 237         .name = "watchdog",
 238         .fops = &ath79_wdt_fops,
 239 };
 240
 241 static int ath79_wdt_probe(struct platform_device *pdev)
 242 {
 243         struct resource *res;
 244         u32 ctrl;
 245         int err;
 246
 247         if (wdt_base)
 248                 return -EBUSY;
 249
 250         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 251         wdt_base = devm_ioremap_resource(&pdev->dev, res);
 252         if (IS_ERR(wdt_base))
 253                 return PTR_ERR(wdt_base);
 254
 255         wdt_clk = devm_clk_get(&pdev->dev, "wdt");
 256         if (IS_ERR(wdt_clk))
 257                 return PTR_ERR(wdt_clk);
 258
 259         err = clk_enable(wdt_clk);
 260         if (err)
 261                 return err;
 262
 263         wdt_freq = clk_get_rate(wdt_clk);
 264         if (!wdt_freq) {
 265                 err = -EINVAL;
 266                 goto err_clk_disable;
 267         }
 268
 269         max_timeout = (0xfffffffful / wdt_freq);
 270         if (timeout < 1 || timeout > max_timeout) {
 271                 timeout = max_timeout;
 272                 dev_info(&pdev->dev,
 273                         "timeout value must be 0 < timeout < %d, using %d\n",
 274                         max_timeout, timeout);
 275         }
 276
 277         ctrl = ath79_wdt_rr(WDOG_REG_CTRL);
 278         boot_status = (ctrl & WDOG_CTRL_LAST_RESET) ? WDIOF_CARDRESET : 0;
 279
 280         err = misc_register(&ath79_wdt_miscdev);
 281         if (err) {
 282                 dev_err(&pdev->dev,
 283                         "unable to register misc device, err=%d\n", err);
 284                 goto err_clk_disable;
 285         }
 286
 287         return 0;
 288
 289 err_clk_disable:
 290         clk_disable(wdt_clk);
 291         return err;
 292 }
 293
 294 static int ath79_wdt_remove(struct platform_device *pdev)
 295 {
 296         misc_deregister(&ath79_wdt_miscdev);
 297         clk_disable(wdt_clk);
 298         return 0;
 299 }
 300
 301 static void ath97_wdt_shutdown(struct platform_device *pdev)
 302 {
 303         ath79_wdt_disable();
 304 }
 305
 306 #ifdef CONFIG_OF
 307 static const struct of_device_id ath79_wdt_match[] = {
 308         { .compatible = "qca,ar7130-wdt" },
 309         {},
 310 };
 311 MODULE_DEVICE_TABLE(of, ath79_wdt_match);
 312 #endif
 313
 314 static struct platform_driver ath79_wdt_driver = {
 315         .probe          = ath79_wdt_probe,
 316         .remove         = ath79_wdt_remove,
 317         .shutdown       = ath97_wdt_shutdown,
 318         .driver         = {
 319                 .name   = DRIVER_NAME,
 320                 .owner  = THIS_MODULE,
 321                 .of_match_table = of_match_ptr(ath79_wdt_match),
 322         },
 323 };
 324
 325 module_platform_driver(ath79_wdt_driver);
 326
 327 MODULE_DESCRIPTION("Atheros AR71XX/AR724X/AR913X hardware watchdog driver");
 328 MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org");
 329 MODULE_AUTHOR("Imre Kaloz <kaloz@openwrt.org");
 330 MODULE_LICENSE("GPL v2");
 331 MODULE_ALIAS("platform:" DRIVER_NAME);