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/init.h>
  17 #include <linux/uaccess.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/clk.h>
  20 #include <linux/err.h>
  21 #include <linux/io.h>
  22 #include <asm/txx9tmr.h>
  23
  24 #define TIMER_MARGIN    60              /* Default is 60 seconds */
  25
  26 static int timeout = TIMER_MARGIN;      /* in seconds */
  27 module_param(timeout, int, 0);
  28 MODULE_PARM_DESC(timeout,
  29         "Watchdog timeout in seconds. "
  30         "(0<timeout<((2^" __MODULE_STRING(TXX9_TIMER_BITS) ")/(IMCLK/256)), "
  31         "default=" __MODULE_STRING(TIMER_MARGIN) ")");
  32
  33 static int nowayout = WATCHDOG_NOWAYOUT;
  34 module_param(nowayout, int, 0);
  35 MODULE_PARM_DESC(nowayout,
  36         "Watchdog cannot be stopped once started "
  37         "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  38
  39 #define WD_TIMER_CCD    7       /* 1/256 */
  40 #define WD_TIMER_CLK    (clk_get_rate(txx9_imclk) / (2 << WD_TIMER_CCD))
  41 #define WD_MAX_TIMEOUT  ((0xffffffff >> (32 - TXX9_TIMER_BITS)) / WD_TIMER_CLK)
  42
  43 static unsigned long txx9wdt_alive;
  44 static int expect_close;
  45 static struct txx9_tmr_reg __iomem *txx9wdt_reg;
  46 static struct clk *txx9_imclk;
  47 static DEFINE_SPINLOCK(txx9_lock);
  48
  49 static void txx9wdt_ping(void)
  50 {
  51         spin_lock(&txx9_lock);
  52         __raw_writel(TXx9_TMWTMR_TWIE | TXx9_TMWTMR_TWC, &txx9wdt_reg->wtmr);
  53         spin_unlock(&txx9_lock);
  54 }
  55
  56 static void txx9wdt_start(void)
  57 {
  58         spin_lock(&txx9_lock);
  59         __raw_writel(WD_TIMER_CLK * timeout, &txx9wdt_reg->cpra);
  60         __raw_writel(WD_TIMER_CCD, &txx9wdt_reg->ccdr);
  61         __raw_writel(0, &txx9wdt_reg->tisr);    /* clear pending interrupt */
  62         __raw_writel(TXx9_TMTCR_TCE | TXx9_TMTCR_CCDE | TXx9_TMTCR_TMODE_WDOG,
  63                      &txx9wdt_reg->tcr);
  64         __raw_writel(TXx9_TMWTMR_TWIE | TXx9_TMWTMR_TWC, &txx9wdt_reg->wtmr);
  65         spin_unlock(&txx9_lock);
  66 }
  67
  68 static void txx9wdt_stop(void)
  69 {
  70         spin_lock(&txx9_lock);
  71         __raw_writel(TXx9_TMWTMR_WDIS, &txx9wdt_reg->wtmr);
  72         __raw_writel(__raw_readl(&txx9wdt_reg->tcr) & ~TXx9_TMTCR_TCE,
  73                      &txx9wdt_reg->tcr);
  74         spin_unlock(&txx9_lock);
  75 }
  76
  77 static int txx9wdt_open(struct inode *inode, struct file *file)
  78 {
  79         if (test_and_set_bit(0, &txx9wdt_alive))
  80                 return -EBUSY;
  81
  82         if (__raw_readl(&txx9wdt_reg->tcr) & TXx9_TMTCR_TCE) {
  83                 clear_bit(0, &txx9wdt_alive);
  84                 return -EBUSY;
  85         }
  86
  87         if (nowayout)
  88                 __module_get(THIS_MODULE);
  89
  90         txx9wdt_start();
  91         return nonseekable_open(inode, file);
  92 }
  93
  94 static int txx9wdt_release(struct inode *inode, struct file *file)
  95 {
  96         if (expect_close)
  97                 txx9wdt_stop();
  98         else {
  99                 printk(KERN_CRIT "txx9wdt: "
 100                        "Unexpected close, not stopping watchdog!\n");
 101                 txx9wdt_ping();
 102         }
 103         clear_bit(0, &txx9wdt_alive);
 104         expect_close = 0;
 105         return 0;
 106 }
 107
 108 static ssize_t txx9wdt_write(struct file *file, const char __user *data,
 109                              size_t len, loff_t *ppos)
 110 {
 111         if (len) {
 112                 if (!nowayout) {
 113                         size_t i;
 114
 115                         expect_close = 0;
 116                         for (i = 0; i != len; i++) {
 117                                 char c;
 118                                 if (get_user(c, data + i))
 119                                         return -EFAULT;
 120                                 if (c == 'V')
 121                                         expect_close = 1;
 122                         }
 123                 }
 124                 txx9wdt_ping();
 125         }
 126         return len;
 127 }
 128
 129 static long txx9wdt_ioctl(struct file *file, unsigned int cmd,
 130                                                         unsigned long arg)
 131 {
 132         void __user *argp = (void __user *)arg;
 133         int __user *p = argp;
 134         int new_timeout;
 135         static const struct watchdog_info ident = {
 136                 .options =              WDIOF_SETTIMEOUT |
 137                                         WDIOF_KEEPALIVEPING |
 138                                         WDIOF_MAGICCLOSE,
 139                 .firmware_version =     0,
 140                 .identity =             "Hardware Watchdog for TXx9",
 141         };
 142
 143         switch (cmd) {
 144         case WDIOC_GETSUPPORT:
 145                 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
 146         case WDIOC_GETSTATUS:
 147         case WDIOC_GETBOOTSTATUS:
 148                 return put_user(0, p);
 149         case WDIOC_KEEPALIVE:
 150                 txx9wdt_ping();
 151                 return 0;
 152         case WDIOC_SETTIMEOUT:
 153                 if (get_user(new_timeout, p))
 154                         return -EFAULT;
 155                 if (new_timeout < 1 || new_timeout > WD_MAX_TIMEOUT)
 156                         return -EINVAL;
 157                 timeout = new_timeout;
 158                 txx9wdt_stop();
 159                 txx9wdt_start();
 160                 /* Fall */
 161         case WDIOC_GETTIMEOUT:
 162                 return put_user(timeout, p);
 163         default:
 164                 return -ENOTTY;
 165         }
 166 }
 167
 168 static const struct file_operations txx9wdt_fops = {
 169         .owner          =       THIS_MODULE,
 170         .llseek         =       no_llseek,
 171         .write          =       txx9wdt_write,
 172         .unlocked_ioctl =       txx9wdt_ioctl,
 173         .open           =       txx9wdt_open,
 174         .release        =       txx9wdt_release,
 175 };
 176
 177 static struct miscdevice txx9wdt_miscdev = {
 178         .minor  =       WATCHDOG_MINOR,
 179         .name   =       "watchdog",
 180         .fops   =       &txx9wdt_fops,
 181 };
 182
 183 static int __init txx9wdt_probe(struct platform_device *dev)
 184 {
 185         struct resource *res;
 186         int ret;
 187
 188         txx9_imclk = clk_get(NULL, "imbus_clk");
 189         if (IS_ERR(txx9_imclk)) {
 190                 ret = PTR_ERR(txx9_imclk);
 191                 txx9_imclk = NULL;
 192                 goto exit;
 193         }
 194         ret = clk_enable(txx9_imclk);
 195         if (ret) {
 196                 clk_put(txx9_imclk);
 197                 txx9_imclk = NULL;
 198                 goto exit;
 199         }
 200
 201         res = platform_get_resource(dev, IORESOURCE_MEM, 0);
 202         if (!res)
 203                 goto exit_busy;
 204         if (!devm_request_mem_region(&dev->dev, res->start, resource_size(res),
 205                                      "txx9wdt"))
 206                 goto exit_busy;
 207         txx9wdt_reg = devm_ioremap(&dev->dev, res->start, resource_size(res));
 208         if (!txx9wdt_reg)
 209                 goto exit_busy;
 210
 211         ret = misc_register(&txx9wdt_miscdev);
 212         if (ret) {
 213                 goto exit;
 214         }
 215
 216         printk(KERN_INFO "Hardware Watchdog Timer for TXx9: "
 217                "timeout=%d sec (max %ld) (nowayout= %d)\n",
 218                timeout, WD_MAX_TIMEOUT, nowayout);
 219
 220         return 0;
 221 exit_busy:
 222         ret = -EBUSY;
 223 exit:
 224         if (txx9_imclk) {
 225                 clk_disable(txx9_imclk);
 226                 clk_put(txx9_imclk);
 227         }
 228         return ret;
 229 }
 230
 231 static int __exit txx9wdt_remove(struct platform_device *dev)
 232 {
 233         misc_deregister(&txx9wdt_miscdev);
 234         clk_disable(txx9_imclk);
 235         clk_put(txx9_imclk);
 236         return 0;
 237 }
 238
 239 static void txx9wdt_shutdown(struct platform_device *dev)
 240 {
 241         txx9wdt_stop();
 242 }
 243
 244 static struct platform_driver txx9wdt_driver = {
 245         .remove = __exit_p(txx9wdt_remove),
 246         .shutdown = txx9wdt_shutdown,
 247         .driver = {
 248                 .name = "txx9wdt",
 249                 .owner = THIS_MODULE,
 250         },
 251 };
 252
 253 static int __init watchdog_init(void)
 254 {
 255         return platform_driver_probe(&txx9wdt_driver, txx9wdt_probe);
 256 }
 257
 258 static void __exit watchdog_exit(void)
 259 {
 260         platform_driver_unregister(&txx9wdt_driver);
 261 }
 262
 263 module_init(watchdog_init);
 264 module_exit(watchdog_exit);
 265
 266 MODULE_DESCRIPTION("TXx9 Watchdog Driver");
 267 MODULE_LICENSE("GPL");
 268 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 269 MODULE_ALIAS("platform:txx9wdt");