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