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
  49 static void txx9wdt_ping(void)
  50 {
  51         __raw_writel(TXx9_TMWTMR_TWIE | TXx9_TMWTMR_TWC, &txx9wdt_reg->wtmr);
  52 }
  53
  54 static void txx9wdt_start(void)
  55 {
  56         __raw_writel(WD_TIMER_CLK * timeout, &txx9wdt_reg->cpra);
  57         __raw_writel(WD_TIMER_CCD, &txx9wdt_reg->ccdr);
  58         __raw_writel(0, &txx9wdt_reg->tisr);    /* clear pending interrupt */
  59         __raw_writel(TXx9_TMTCR_TCE | TXx9_TMTCR_CCDE | TXx9_TMTCR_TMODE_WDOG,
  60                      &txx9wdt_reg->tcr);
  61         __raw_writel(TXx9_TMWTMR_TWIE | TXx9_TMWTMR_TWC, &txx9wdt_reg->wtmr);
  62 }
  63
  64 static void txx9wdt_stop(void)
  65 {
  66         __raw_writel(TXx9_TMWTMR_WDIS, &txx9wdt_reg->wtmr);
  67         __raw_writel(__raw_readl(&txx9wdt_reg->tcr) & ~TXx9_TMTCR_TCE,
  68                      &txx9wdt_reg->tcr);
  69 }
  70
  71 static int txx9wdt_open(struct inode *inode, struct file *file)
  72 {
  73         if (test_and_set_bit(0, &txx9wdt_alive))
  74                 return -EBUSY;
  75
  76         if (__raw_readl(&txx9wdt_reg->tcr) & TXx9_TMTCR_TCE) {
  77                 clear_bit(0, &txx9wdt_alive);
  78                 return -EBUSY;
  79         }
  80
  81         if (nowayout)
  82                 __module_get(THIS_MODULE);
  83
  84         txx9wdt_start();
  85         return nonseekable_open(inode, file);
  86 }
  87
  88 static int txx9wdt_release(struct inode *inode, struct file *file)
  89 {
  90         if (expect_close)
  91                 txx9wdt_stop();
  92         else {
  93                 printk(KERN_CRIT "txx9wdt: "
  94                        "Unexpected close, not stopping watchdog!\n");
  95                 txx9wdt_ping();
  96         }
  97         clear_bit(0, &txx9wdt_alive);
  98         expect_close = 0;
  99         return 0;
 100 }
 101
 102 static ssize_t txx9wdt_write(struct file *file, const char __user *data,
 103                              size_t len, loff_t *ppos)
 104 {
 105         if (len) {
 106                 if (!nowayout) {
 107                         size_t i;
 108
 109                         expect_close = 0;
 110                         for (i = 0; i != len; i++) {
 111                                 char c;
 112                                 if (get_user(c, data + i))
 113                                         return -EFAULT;
 114                                 if (c == 'V')
 115                                         expect_close = 1;
 116                         }
 117                 }
 118                 txx9wdt_ping();
 119         }
 120         return len;
 121 }
 122
 123 static int txx9wdt_ioctl(struct inode *inode, struct file *file,
 124         unsigned int cmd, unsigned long arg)
 125 {
 126         void __user *argp = (void __user *)arg;
 127         int __user *p = argp;
 128         int new_timeout;
 129         static struct watchdog_info ident = {
 130                 .options =              WDIOF_SETTIMEOUT |
 131                                         WDIOF_KEEPALIVEPING |
 132                                         WDIOF_MAGICCLOSE,
 133                 .firmware_version =     0,
 134                 .identity =             "Hardware Watchdog for TXx9",
 135         };
 136
 137         switch (cmd) {
 138         default:
 139                 return -ENOTTY;
 140         case WDIOC_GETSUPPORT:
 141                 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
 142         case WDIOC_GETSTATUS:
 143         case WDIOC_GETBOOTSTATUS:
 144                 return put_user(0, p);
 145         case WDIOC_KEEPALIVE:
 146                 txx9wdt_ping();
 147                 return 0;
 148         case WDIOC_SETTIMEOUT:
 149                 if (get_user(new_timeout, p))
 150                         return -EFAULT;
 151                 if (new_timeout < 1 || new_timeout > WD_MAX_TIMEOUT)
 152                         return -EINVAL;
 153                 timeout = new_timeout;
 154                 txx9wdt_stop();
 155                 txx9wdt_start();
 156                 /* Fall */
 157         case WDIOC_GETTIMEOUT:
 158                 return put_user(timeout, p);
 159         }
 160 }
 161
 162 static int txx9wdt_notify_sys(struct notifier_block *this, unsigned long code,
 163         void *unused)
 164 {
 165         if (code == SYS_DOWN || code == SYS_HALT)
 166                 txx9wdt_stop();
 167         return NOTIFY_DONE;
 168 }
 169
 170 static const struct file_operations txx9wdt_fops = {
 171         .owner =        THIS_MODULE,
 172         .llseek =       no_llseek,
 173         .write =        txx9wdt_write,
 174         .ioctl =        txx9wdt_ioctl,
 175         .open =         txx9wdt_open,
 176         .release =      txx9wdt_release,
 177 };
 178
 179 static struct miscdevice txx9wdt_miscdev = {
 180         .minor =        WATCHDOG_MINOR,
 181         .name =         "watchdog",
 182         .fops =         &txx9wdt_fops,
 183 };
 184
 185 static struct notifier_block txx9wdt_notifier = {
 186         .notifier_call = txx9wdt_notify_sys
 187 };
 188
 189 static int __init txx9wdt_probe(struct platform_device *dev)
 190 {
 191         struct resource *res;
 192         int ret;
 193
 194         txx9_imclk = clk_get(NULL, "imbus_clk");
 195         if (IS_ERR(txx9_imclk)) {
 196                 ret = PTR_ERR(txx9_imclk);
 197                 txx9_imclk = NULL;
 198                 goto exit;
 199         }
 200         ret = clk_enable(txx9_imclk);
 201         if (ret) {
 202                 clk_put(txx9_imclk);
 203                 txx9_imclk = NULL;
 204                 goto exit;
 205         }
 206
 207         res = platform_get_resource(dev, IORESOURCE_MEM, 0);
 208         if (!res)
 209                 goto exit_busy;
 210         if (!devm_request_mem_region(&dev->dev,
 211                                      res->start, res->end - res->start + 1,
 212                                      "txx9wdt"))
 213                 goto exit_busy;
 214         txx9wdt_reg = devm_ioremap(&dev->dev,
 215                                    res->start, res->end - res->start + 1);
 216         if (!txx9wdt_reg)
 217                 goto exit_busy;
 218
 219         ret = register_reboot_notifier(&txx9wdt_notifier);
 220         if (ret)
 221                 goto exit;
 222
 223         ret = misc_register(&txx9wdt_miscdev);
 224         if (ret) {
 225                 unregister_reboot_notifier(&txx9wdt_notifier);
 226                 goto exit;
 227         }
 228
 229         printk(KERN_INFO "Hardware Watchdog Timer for TXx9: "
 230                "timeout=%d sec (max %ld) (nowayout= %d)\n",
 231                timeout, WD_MAX_TIMEOUT, nowayout);
 232
 233         return 0;
 234 exit_busy:
 235         ret = -EBUSY;
 236 exit:
 237         if (txx9_imclk) {
 238                 clk_disable(txx9_imclk);
 239                 clk_put(txx9_imclk);
 240         }
 241         return ret;
 242 }
 243
 244 static int __exit txx9wdt_remove(struct platform_device *dev)
 245 {
 246         misc_deregister(&txx9wdt_miscdev);
 247         unregister_reboot_notifier(&txx9wdt_notifier);
 248         clk_disable(txx9_imclk);
 249         clk_put(txx9_imclk);
 250         return 0;
 251 }
 252
 253 static struct platform_driver txx9wdt_driver = {
 254         .remove = __exit_p(txx9wdt_remove),
 255         .driver = {
 256                 .name = "txx9wdt",
 257                 .owner = THIS_MODULE,
 258         },
 259 };
 260
 261 static int __init watchdog_init(void)
 262 {
 263         return platform_driver_probe(&txx9wdt_driver, txx9wdt_probe);
 264 }
 265
 266 static void __exit watchdog_exit(void)
 267 {
 268         platform_driver_unregister(&txx9wdt_driver);
 269 }
 270
 271 module_init(watchdog_init);
 272 module_exit(watchdog_exit);
 273
 274 MODULE_DESCRIPTION("TXx9 Watchdog Driver");
 275 MODULE_LICENSE("GPL");
 276 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);