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/delay.h>
  24 #include <linux/errno.h>
  25 #include <linux/fs.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 #include <linux/uaccess.h>
  39
  40 #define DRIVER_NAME     "ath79-wdt"
  41
  42 #define WDT_TIMEOUT     15      /* seconds */
  43
  44 #define WDOG_REG_CTRL           0x00
  45 #define WDOG_REG_TIMER          0x04
  46
  47 #define WDOG_CTRL_LAST_RESET    BIT(31)
  48 #define WDOG_CTRL_ACTION_MASK   3
  49 #define WDOG_CTRL_ACTION_NONE   0       /* no action */
  50 #define WDOG_CTRL_ACTION_GPI    1       /* general purpose interrupt */
  51 #define WDOG_CTRL_ACTION_NMI    2       /* NMI */
  52 #define WDOG_CTRL_ACTION_FCR    3       /* full chip reset */
  53
  54 static bool nowayout = WATCHDOG_NOWAYOUT;
  55 module_param(nowayout, bool, 0);
  56 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
  57                            "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  58
  59 static int timeout = WDT_TIMEOUT;
  60 module_param(timeout, int, 0);
  61 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds "
  62                           "(default=" __MODULE_STRING(WDT_TIMEOUT) "s)");
  63
  64 static unsigned long wdt_flags;
  65
  66 #define WDT_FLAGS_BUSY          0
  67 #define WDT_FLAGS_EXPECT_CLOSE  1
  68
  69 static struct clk *wdt_clk;
  70 static unsigned long wdt_freq;
  71 static int boot_status;
  72 static int max_timeout;
  73 static void __iomem *wdt_base;
  74
  75 static inline void ath79_wdt_wr(unsigned reg, u32 val)
  76 {
  77         iowrite32(val, wdt_base + reg);
  78 }
  79
  80 static inline u32 ath79_wdt_rr(unsigned reg)
  81 {
  82         return ioread32(wdt_base + reg);
  83 }
  84
  85 static inline void ath79_wdt_keepalive(void)
  86 {
  87         ath79_wdt_wr(WDOG_REG_TIMER, wdt_freq * timeout);
  88         /* flush write */
  89         ath79_wdt_rr(WDOG_REG_TIMER);
  90 }
  91
  92 static inline void ath79_wdt_enable(void)
  93 {
  94         ath79_wdt_keepalive();
  95
  96         /*
  97          * Updating the TIMER register requires a few microseconds
  98          * on the AR934x SoCs at least. Use a small delay to ensure
  99          * that the TIMER register is updated within the hardware
 100          * before enabling the watchdog.
 101          */
 102         udelay(2);
 103
 104         ath79_wdt_wr(WDOG_REG_CTRL, WDOG_CTRL_ACTION_FCR);
 105         /* flush write */
 106         ath79_wdt_rr(WDOG_REG_CTRL);
 107 }
 108
 109 static inline void ath79_wdt_disable(void)
 110 {
 111         ath79_wdt_wr(WDOG_REG_CTRL, WDOG_CTRL_ACTION_NONE);
 112         /* flush write */
 113         ath79_wdt_rr(WDOG_REG_CTRL);
 114 }
 115
 116 static int ath79_wdt_set_timeout(int val)
 117 {
 118         if (val < 1 || val > max_timeout)
 119                 return -EINVAL;
 120
 121         timeout = val;
 122         ath79_wdt_keepalive();
 123
 124         return 0;
 125 }
 126
 127 static int ath79_wdt_open(struct inode *inode, struct file *file)
 128 {
 129         if (test_and_set_bit(WDT_FLAGS_BUSY, &wdt_flags))
 130                 return -EBUSY;
 131
 132         clear_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags);
 133         ath79_wdt_enable();
 134
 135         return nonseekable_open(inode, file);
 136 }
 137
 138 static int ath79_wdt_release(struct inode *inode, struct file *file)
 139 {
 140         if (test_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags))
 141                 ath79_wdt_disable();
 142         else {
 143                 pr_crit("device closed unexpectedly, watchdog timer will not stop!\n");
 144                 ath79_wdt_keepalive();
 145         }
 146
 147         clear_bit(WDT_FLAGS_BUSY, &wdt_flags);
 148         clear_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags);
 149
 150         return 0;
 151 }
 152
 153 static ssize_t ath79_wdt_write(struct file *file, const char *data,
 154                                 size_t len, loff_t *ppos)
 155 {
 156         if (len) {
 157                 if (!nowayout) {
 158                         size_t i;
 159
 160                         clear_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags);
 161
 162                         for (i = 0; i != len; i++) {
 163                                 char c;
 164
 165                                 if (get_user(c, data + i))
 166                                         return -EFAULT;
 167
 168                                 if (c == 'V')
 169                                         set_bit(WDT_FLAGS_EXPECT_CLOSE,
 170                                                 &wdt_flags);
 171                         }
 172                 }
 173
 174                 ath79_wdt_keepalive();
 175         }
 176
 177         return len;
 178 }
 179
 180 static const struct watchdog_info ath79_wdt_info = {
 181         .options                = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
 182                                   WDIOF_MAGICCLOSE | WDIOF_CARDRESET,
 183         .firmware_version       = 0,
 184         .identity               = "ATH79 watchdog",
 185 };
 186
 187 static long ath79_wdt_ioctl(struct file *file, unsigned int cmd,
 188                             unsigned long arg)
 189 {
 190         void __user *argp = (void __user *)arg;
 191         int __user *p = argp;
 192         int err;
 193         int t;
 194
 195         switch (cmd) {
 196         case WDIOC_GETSUPPORT:
 197                 err = copy_to_user(argp, &ath79_wdt_info,
 198                                    sizeof(ath79_wdt_info)) ? -EFAULT : 0;
 199                 break;
 200
 201         case WDIOC_GETSTATUS:
 202                 err = put_user(0, p);
 203                 break;
 204
 205         case WDIOC_GETBOOTSTATUS:
 206                 err = put_user(boot_status, p);
 207                 break;
 208
 209         case WDIOC_KEEPALIVE:
 210                 ath79_wdt_keepalive();
 211                 err = 0;
 212                 break;
 213
 214         case WDIOC_SETTIMEOUT:
 215                 err = get_user(t, p);
 216                 if (err)
 217                         break;
 218
 219                 err = ath79_wdt_set_timeout(t);
 220                 if (err)
 221                         break;
 222
 223                 /* fallthrough */
 224         case WDIOC_GETTIMEOUT:
 225                 err = put_user(timeout, p);
 226                 break;
 227
 228         default:
 229                 err = -ENOTTY;
 230                 break;
 231         }
 232
 233         return err;
 234 }
 235
 236 static const struct file_operations ath79_wdt_fops = {
 237         .owner          = THIS_MODULE,
 238         .llseek         = no_llseek,
 239         .write          = ath79_wdt_write,
 240         .unlocked_ioctl = ath79_wdt_ioctl,
 241         .open           = ath79_wdt_open,
 242         .release        = ath79_wdt_release,
 243 };
 244
 245 static struct miscdevice ath79_wdt_miscdev = {
 246         .minor = WATCHDOG_MINOR,
 247         .name = "watchdog",
 248         .fops = &ath79_wdt_fops,
 249 };
 250
 251 static int ath79_wdt_probe(struct platform_device *pdev)
 252 {
 253         struct resource *res;
 254         u32 ctrl;
 255         int err;
 256
 257         if (wdt_base)
 258                 return -EBUSY;
 259
 260         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 261         wdt_base = devm_ioremap_resource(&pdev->dev, res);
 262         if (IS_ERR(wdt_base))
 263                 return PTR_ERR(wdt_base);
 264
 265         wdt_clk = devm_clk_get(&pdev->dev, "wdt");
 266         if (IS_ERR(wdt_clk))
 267                 return PTR_ERR(wdt_clk);
 268
 269         err = clk_prepare_enable(wdt_clk);
 270         if (err)
 271                 return err;
 272
 273         wdt_freq = clk_get_rate(wdt_clk);
 274         if (!wdt_freq) {
 275                 err = -EINVAL;
 276                 goto err_clk_disable;
 277         }
 278
 279         max_timeout = (0xfffffffful / wdt_freq);
 280         if (timeout < 1 || timeout > max_timeout) {
 281                 timeout = max_timeout;
 282                 dev_info(&pdev->dev,
 283                         "timeout value must be 0 < timeout < %d, using %d\n",
 284                         max_timeout, timeout);
 285         }
 286
 287         ctrl = ath79_wdt_rr(WDOG_REG_CTRL);
 288         boot_status = (ctrl & WDOG_CTRL_LAST_RESET) ? WDIOF_CARDRESET : 0;
 289
 290         err = misc_register(&ath79_wdt_miscdev);
 291         if (err) {
 292                 dev_err(&pdev->dev,
 293                         "unable to register misc device, err=%d\n", err);
 294                 goto err_clk_disable;
 295         }
 296
 297         return 0;
 298
 299 err_clk_disable:
 300         clk_disable_unprepare(wdt_clk);
 301         return err;
 302 }
 303
 304 static int ath79_wdt_remove(struct platform_device *pdev)
 305 {
 306         misc_deregister(&ath79_wdt_miscdev);
 307         clk_disable_unprepare(wdt_clk);
 308         return 0;
 309 }
 310
 311 static void ath97_wdt_shutdown(struct platform_device *pdev)
 312 {
 313         ath79_wdt_disable();
 314 }
 315
 316 #ifdef CONFIG_OF
 317 static const struct of_device_id ath79_wdt_match[] = {
 318         { .compatible = "qca,ar7130-wdt" },
 319         {},
 320 };
 321 MODULE_DEVICE_TABLE(of, ath79_wdt_match);
 322 #endif
 323
 324 static struct platform_driver ath79_wdt_driver = {
 325         .probe          = ath79_wdt_probe,
 326         .remove         = ath79_wdt_remove,
 327         .shutdown       = ath97_wdt_shutdown,
 328         .driver         = {
 329                 .name   = DRIVER_NAME,
 330                 .of_match_table = of_match_ptr(ath79_wdt_match),
 331         },
 332 };
 333
 334 module_platform_driver(ath79_wdt_driver);
 335
 336 MODULE_DESCRIPTION("Atheros AR71XX/AR724X/AR913X hardware watchdog driver");
 337 MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org");
 338 MODULE_AUTHOR("Imre Kaloz <kaloz@openwrt.org");
 339 MODULE_LICENSE("GPL v2");
 340 MODULE_ALIAS("platform:" DRIVER_NAME);