drivers/watchdog/txx9wdt.c

   1 /*
   2  * txx9wdt: A Hardware Watchdog Driver for TXx9 SoCs
   3  *
   4  * Copyright (C) 2007 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10 #include <linux/module.h>
  11 #include <linux/moduleparam.h>
  12 #include <linux/types.h>
  13 #include <linux/miscdevice.h>
  14 #include <linux/watchdog.h>
  15 #include <linux/fs.h>
  16 #include <linux/reboot.h>
  17 #include <linux/init.h>
  18 #include <linux/uaccess.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/clk.h>
  21 #include <linux/err.h>
  22 #include <linux/io.h>
  23 #include <asm/txx9tmr.h>
  24
  25 #define TIMER_MARGIN    60              /* Default is 60 seconds */
  26
  27 static int timeout = TIMER_MARGIN;      /* in seconds */
  28 module_param(timeout, int, 0);
  29 MODULE_PARM_DESC(timeout,
  30         "Watchdog timeout in seconds. "
  31         "(0<timeout<((2^" __MODULE_STRING(TXX9_TIMER_BITS) ")/(IMCLK/256)), "
  32         "default=" __MODULE_STRING(TIMER_MARGIN) ")");
  33
  34 static int nowayout = WATCHDOG_NOWAYOUT;
  35 module_param(nowayout, int, 0);
  36 MODULE_PARM_DESC(nowayout,
  37         "Watchdog cannot be stopped once started "
  38         "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  39
  40 #define WD_TIMER_CCD    7       /* 1/256 */
  41 #define WD_TIMER_CLK    (clk_get_rate(txx9_imclk) / (2 << WD_TIMER_CCD))
  42 #define WD_MAX_TIMEOUT  ((0xffffffff >> (32 - TXX9_TIMER_BITS)) / WD_TIMER_CLK)
  43
  44 static unsigned long txx9wdt_alive;
  45 static int expect_close;
  46 static struct txx9_tmr_reg __iomem *txx9wdt_reg;
  47 static struct clk *txx9_imclk;
  48 static DEFINE_SPINLOCK(txx9_lock);
  49
  50 static void txx9wdt_ping(void)
  51 {
  52         spin_lock(&txx9_lock);
  53         __raw_writel(TXx9_TMWTMR_TWIE | TXx9_TMWTMR_TWC, &txx9wdt_reg->wtmr);
  54         spin_unlock(&txx9_lock);
  55 }
  56
  57 static void txx9wdt_start(void)
  58 {
  59         spin_lock(&txx9_lock);
  60         __raw_writel(WD_TIMER_CLK * timeout, &txx9wdt_reg->cpra);
  61         __raw_writel(WD_TIMER_CCD, &txx9wdt_reg->ccdr);
  62         __raw_writel(0, &txx9wdt_reg->tisr);    /* clear pending interrupt */
  63         __raw_writel(TXx9_TMTCR_TCE | TXx9_TMTCR_CCDE | TXx9_TMTCR_TMODE_WDOG,
  64                      &txx9wdt_reg->tcr);
  65         __raw_writel(TXx9_TMWTMR_TWIE | TXx9_TMWTMR_TWC, &txx9wdt_reg->wtmr);
  66         spin_unlock(&txx9_lock);
  67 }
  68
  69 static void txx9wdt_stop(void)
  70 {
  71         spin_lock(&txx9_lock);
  72         __raw_writel(TXx9_TMWTMR_WDIS, &txx9wdt_reg->wtmr);
  73         __raw_writel(__raw_readl(&txx9wdt_reg->tcr) & ~TXx9_TMTCR_TCE,
  74                      &txx9wdt_reg->tcr);
  75         spin_unlock(&txx9_lock);
  76 }
  77
  78 static int txx9wdt_open(struct inode *inode, struct file *file)
  79 {
  80         if (test_and_set_bit(0, &txx9wdt_alive))
  81                 return -EBUSY;
  82
  83         if (__raw_readl(&txx9wdt_reg->tcr) & TXx9_TMTCR_TCE) {
  84                 clear_bit(0, &txx9wdt_alive);
  85                 return -EBUSY;
  86         }
  87
  88         if (nowayout)
  89                 __module_get(THIS_MODULE);
  90
  91         txx9wdt_start();
  92         return nonseekable_open(inode, file);
  93 }
  94
  95 static int txx9wdt_release(struct inode *inode, struct file *file)
  96 {
  97         if (expect_close)
  98                 txx9wdt_stop();
  99         else {
 100                 printk(KERN_CRIT "txx9wdt: "
 101                        "Unexpected close, not stopping watchdog!\n");
 102                 txx9wdt_ping();
 103         }
 104         clear_bit(0, &txx9wdt_alive);
 105         expect_close = 0;
 106         return 0;
 107 }
 108
 109 static ssize_t txx9wdt_write(struct file *file, const char __user *data,
 110                              size_t len, loff_t *ppos)
 111 {
 112         if (len) {
 113                 if (!nowayout) {
 114                         size_t i;
 115
 116                         expect_close = 0;
 117                         for (i = 0; i != len; i++) {
 118                                 char c;
 119                                 if (get_user(c, data + i))
 120                                         return -EFAULT;
 121                                 if (c == 'V')
 122                                         expect_close = 1;
 123                         }
 124                 }
 125                 txx9wdt_ping();
 126         }
 127         return len;
 128 }
 129
 130 static long txx9wdt_ioctl(struct file *file, unsigned int cmd,
 131                                                         unsigned long arg)
 132 {
 133         void __user *argp = (void __user *)arg;
 134         int __user *p = argp;
 135         int new_timeout;
 136         static const struct watchdog_info ident = {
 137                 .options =              WDIOF_SETTIMEOUT |
 138                                         WDIOF_KEEPALIVEPING |
 139                                         WDIOF_MAGICCLOSE,
 140                 .firmware_version =     0,
 141                 .identity =             "Hardware Watchdog for TXx9",
 142         };
 143
 144         switch (cmd) {
 145         case WDIOC_GETSUPPORT:
 146                 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
 147         case WDIOC_GETSTATUS:
 148         case WDIOC_GETBOOTSTATUS:
 149                 return put_user(0, p);
 150         case WDIOC_KEEPALIVE:
 151                 txx9wdt_ping();
 152                 return 0;
 153         case WDIOC_SETTIMEOUT:
 154                 if (get_user(new_timeout, p))
 155                         return -EFAULT;
 156                 if (new_timeout < 1 || new_timeout > WD_MAX_TIMEOUT)
 157                         return -EINVAL;
 158                 timeout = new_timeout;
 159                 txx9wdt_stop();
 160                 txx9wdt_start();
 161                 /* Fall */
 162         case WDIOC_GETTIMEOUT:
 163                 return put_user(timeout, p);
 164         default:
 165                 return -ENOTTY;
 166         }
 167 }
 168
 169 static int txx9wdt_notify_sys(struct notifier_block *this, unsigned long code,
 170         void *unused)
 171 {
 172         if (code == SYS_DOWN || code == SYS_HALT)
 173                 txx9wdt_stop();
 174         return NOTIFY_DONE;
 175 }
 176
 177 static const struct file_operations txx9wdt_fops = {
 178         .owner          =       THIS_MODULE,
 179         .llseek         =       no_llseek,
 180         .write          =       txx9wdt_write,
 181         .unlocked_ioctl =       txx9wdt_ioctl,
 182         .open           =       txx9wdt_open,
 183         .release        =       txx9wdt_release,
 184 };
 185
 186 static struct miscdevice txx9wdt_miscdev = {
 187         .minor  =       WATCHDOG_MINOR,
 188         .name   =       "watchdog",
 189         .fops   =       &txx9wdt_fops,
 190 };
 191
 192 static struct notifier_block txx9wdt_notifier = {
 193         .notifier_call = txx9wdt_notify_sys,
 194 };
 195
 196 static int __init txx9wdt_probe(struct platform_device *dev)
 197 {
 198         struct resource *res;
 199         int ret;
 200
 201         txx9_imclk = clk_get(NULL, "imbus_clk");
 202         if (IS_ERR(txx9_imclk)) {
 203                 ret = PTR_ERR(txx9_imclk);
 204                 txx9_imclk = NULL;
 205                 goto exit;
 206         }
 207         ret = clk_enable(txx9_imclk);
 208         if (ret) {
 209                 clk_put(txx9_imclk);
 210                 txx9_imclk = NULL;
 211                 goto exit;
 212         }
 213
 214         res = platform_get_resource(dev, IORESOURCE_MEM, 0);
 215         if (!res)
 216                 goto exit_busy;
 217         if (!devm_request_mem_region(&dev->dev,
 218                                      res->start, res->end - res->start + 1,
 219                                      "txx9wdt"))
 220                 goto exit_busy;
 221         txx9wdt_reg = devm_ioremap(&dev->dev,
 222                                    res->start, res->end - res->start + 1);
 223         if (!txx9wdt_reg)
 224                 goto exit_busy;
 225
 226         ret = register_reboot_notifier(&txx9wdt_notifier);
 227         if (ret)
 228                 goto exit;
 229
 230         ret = misc_register(&txx9wdt_miscdev);
 231         if (ret) {
 232                 unregister_reboot_notifier(&txx9wdt_notifier);
 233                 goto exit;
 234         }
 235
 236         printk(KERN_INFO "Hardware Watchdog Timer for TXx9: "
 237                "timeout=%d sec (max %ld) (nowayout= %d)\n",
 238                timeout, WD_MAX_TIMEOUT, nowayout);
 239
 240         return 0;
 241 exit_busy:
 242         ret = -EBUSY;
 243 exit:
 244         if (txx9_imclk) {
 245                 clk_disable(txx9_imclk);
 246                 clk_put(txx9_imclk);
 247         }
 248         return ret;
 249 }
 250
 251 static int __exit txx9wdt_remove(struct platform_device *dev)
 252 {
 253         misc_deregister(&txx9wdt_miscdev);
 254         unregister_reboot_notifier(&txx9wdt_notifier);
 255         clk_disable(txx9_imclk);
 256         clk_put(txx9_imclk);
 257         return 0;
 258 }
 259
 260 static struct platform_driver txx9wdt_driver = {
 261         .remove = __exit_p(txx9wdt_remove),
 262         .driver = {
 263                 .name = "txx9wdt",
 264                 .owner = THIS_MODULE,
 265         },
 266 };
 267
 268 static int __init watchdog_init(void)
 269 {
 270         return platform_driver_probe(&txx9wdt_driver, txx9wdt_probe);
 271 }
 272
 273 static void __exit watchdog_exit(void)
 274 {
 275         platform_driver_unregister(&txx9wdt_driver);
 276 }
 277
 278 module_init(watchdog_init);
 279 module_exit(watchdog_exit);
 280
 281 MODULE_DESCRIPTION("TXx9 Watchdog Driver");
 282 MODULE_LICENSE("GPL");
 283 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 284 MODULE_ALIAS("platform:txx9wdt");