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
  11 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  12
  13 #include <linux/module.h>
  14 #include <linux/moduleparam.h>
  15 #include <linux/types.h>
  16 #include <linux/miscdevice.h>
  17 #include <linux/watchdog.h>
  18 #include <linux/fs.h>
  19 #include <linux/init.h>
  20 #include <linux/uaccess.h>
  21 #include <linux/platform_device.h>
  22 #include <linux/clk.h>
  23 #include <linux/err.h>
  24 #include <linux/io.h>
  25 #include <asm/txx9tmr.h>
  26
  27 #define TIMER_MARGIN    60              /* Default is 60 seconds */
  28
  29 static int timeout = TIMER_MARGIN;      /* in seconds */
  30 module_param(timeout, int, 0);
  31 MODULE_PARM_DESC(timeout,
  32         "Watchdog timeout in seconds. "
  33         "(0<timeout<((2^" __MODULE_STRING(TXX9_TIMER_BITS) ")/(IMCLK/256)), "
  34         "default=" __MODULE_STRING(TIMER_MARGIN) ")");
  35
  36 static int nowayout = WATCHDOG_NOWAYOUT;
  37 module_param(nowayout, int, 0);
  38 MODULE_PARM_DESC(nowayout,
  39         "Watchdog cannot be stopped once started "
  40         "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  41
  42 #define WD_TIMER_CCD    7       /* 1/256 */
  43 #define WD_TIMER_CLK    (clk_get_rate(txx9_imclk) / (2 << WD_TIMER_CCD))
  44 #define WD_MAX_TIMEOUT  ((0xffffffff >> (32 - TXX9_TIMER_BITS)) / WD_TIMER_CLK)
  45
  46 static unsigned long txx9wdt_alive;
  47 static int expect_close;
  48 static struct txx9_tmr_reg __iomem *txx9wdt_reg;
  49 static struct clk *txx9_imclk;
  50 static DEFINE_SPINLOCK(txx9_lock);
  51
  52 static void txx9wdt_ping(void)
  53 {
  54         spin_lock(&txx9_lock);
  55         __raw_writel(TXx9_TMWTMR_TWIE | TXx9_TMWTMR_TWC, &txx9wdt_reg->wtmr);
  56         spin_unlock(&txx9_lock);
  57 }
  58
  59 static void txx9wdt_start(void)
  60 {
  61         spin_lock(&txx9_lock);
  62         __raw_writel(WD_TIMER_CLK * timeout, &txx9wdt_reg->cpra);
  63         __raw_writel(WD_TIMER_CCD, &txx9wdt_reg->ccdr);
  64         __raw_writel(0, &txx9wdt_reg->tisr);    /* clear pending interrupt */
  65         __raw_writel(TXx9_TMTCR_TCE | TXx9_TMTCR_CCDE | TXx9_TMTCR_TMODE_WDOG,
  66                      &txx9wdt_reg->tcr);
  67         __raw_writel(TXx9_TMWTMR_TWIE | TXx9_TMWTMR_TWC, &txx9wdt_reg->wtmr);
  68         spin_unlock(&txx9_lock);
  69 }
  70
  71 static void txx9wdt_stop(void)
  72 {
  73         spin_lock(&txx9_lock);
  74         __raw_writel(TXx9_TMWTMR_WDIS, &txx9wdt_reg->wtmr);
  75         __raw_writel(__raw_readl(&txx9wdt_reg->tcr) & ~TXx9_TMTCR_TCE,
  76                      &txx9wdt_reg->tcr);
  77         spin_unlock(&txx9_lock);
  78 }
  79
  80 static int txx9wdt_open(struct inode *inode, struct file *file)
  81 {
  82         if (test_and_set_bit(0, &txx9wdt_alive))
  83                 return -EBUSY;
  84
  85         if (__raw_readl(&txx9wdt_reg->tcr) & TXx9_TMTCR_TCE) {
  86                 clear_bit(0, &txx9wdt_alive);
  87                 return -EBUSY;
  88         }
  89
  90         if (nowayout)
  91                 __module_get(THIS_MODULE);
  92
  93         txx9wdt_start();
  94         return nonseekable_open(inode, file);
  95 }
  96
  97 static int txx9wdt_release(struct inode *inode, struct file *file)
  98 {
  99         if (expect_close)
 100                 txx9wdt_stop();
 101         else {
 102                 pr_crit("Unexpected close, not stopping watchdog!\n");
 103                 txx9wdt_ping();
 104         }
 105         clear_bit(0, &txx9wdt_alive);
 106         expect_close = 0;
 107         return 0;
 108 }
 109
 110 static ssize_t txx9wdt_write(struct file *file, const char __user *data,
 111                              size_t len, loff_t *ppos)
 112 {
 113         if (len) {
 114                 if (!nowayout) {
 115                         size_t i;
 116
 117                         expect_close = 0;
 118                         for (i = 0; i != len; i++) {
 119                                 char c;
 120                                 if (get_user(c, data + i))
 121                                         return -EFAULT;
 122                                 if (c == 'V')
 123                                         expect_close = 1;
 124                         }
 125                 }
 126                 txx9wdt_ping();
 127         }
 128         return len;
 129 }
 130
 131 static long txx9wdt_ioctl(struct file *file, unsigned int cmd,
 132                                                         unsigned long arg)
 133 {
 134         void __user *argp = (void __user *)arg;
 135         int __user *p = argp;
 136         int new_timeout;
 137         static const struct watchdog_info ident = {
 138                 .options =              WDIOF_SETTIMEOUT |
 139                                         WDIOF_KEEPALIVEPING |
 140                                         WDIOF_MAGICCLOSE,
 141                 .firmware_version =     0,
 142                 .identity =             "Hardware Watchdog for TXx9",
 143         };
 144
 145         switch (cmd) {
 146         case WDIOC_GETSUPPORT:
 147                 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
 148         case WDIOC_GETSTATUS:
 149         case WDIOC_GETBOOTSTATUS:
 150                 return put_user(0, p);
 151         case WDIOC_KEEPALIVE:
 152                 txx9wdt_ping();
 153                 return 0;
 154         case WDIOC_SETTIMEOUT:
 155                 if (get_user(new_timeout, p))
 156                         return -EFAULT;
 157                 if (new_timeout < 1 || new_timeout > WD_MAX_TIMEOUT)
 158                         return -EINVAL;
 159                 timeout = new_timeout;
 160                 txx9wdt_stop();
 161                 txx9wdt_start();
 162                 /* Fall */
 163         case WDIOC_GETTIMEOUT:
 164                 return put_user(timeout, p);
 165         default:
 166                 return -ENOTTY;
 167         }
 168 }
 169
 170 static const struct file_operations txx9wdt_fops = {
 171         .owner          =       THIS_MODULE,
 172         .llseek         =       no_llseek,
 173         .write          =       txx9wdt_write,
 174         .unlocked_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 int __init txx9wdt_probe(struct platform_device *dev)
 186 {
 187         struct resource *res;
 188         int ret;
 189
 190         txx9_imclk = clk_get(NULL, "imbus_clk");
 191         if (IS_ERR(txx9_imclk)) {
 192                 ret = PTR_ERR(txx9_imclk);
 193                 txx9_imclk = NULL;
 194                 goto exit;
 195         }
 196         ret = clk_enable(txx9_imclk);
 197         if (ret) {
 198                 clk_put(txx9_imclk);
 199                 txx9_imclk = NULL;
 200                 goto exit;
 201         }
 202
 203         res = platform_get_resource(dev, IORESOURCE_MEM, 0);
 204         if (!res)
 205                 goto exit_busy;
 206         if (!devm_request_mem_region(&dev->dev, res->start, resource_size(res),
 207                                      "txx9wdt"))
 208                 goto exit_busy;
 209         txx9wdt_reg = devm_ioremap(&dev->dev, res->start, resource_size(res));
 210         if (!txx9wdt_reg)
 211                 goto exit_busy;
 212
 213         ret = misc_register(&txx9wdt_miscdev);
 214         if (ret) {
 215                 goto exit;
 216         }
 217
 218         pr_info("Hardware Watchdog Timer: timeout=%d sec (max %ld) (nowayout= %d)\n",
 219                 timeout, WD_MAX_TIMEOUT, nowayout);
 220
 221         return 0;
 222 exit_busy:
 223         ret = -EBUSY;
 224 exit:
 225         if (txx9_imclk) {
 226                 clk_disable(txx9_imclk);
 227                 clk_put(txx9_imclk);
 228         }
 229         return ret;
 230 }
 231
 232 static int __exit txx9wdt_remove(struct platform_device *dev)
 233 {
 234         misc_deregister(&txx9wdt_miscdev);
 235         clk_disable(txx9_imclk);
 236         clk_put(txx9_imclk);
 237         return 0;
 238 }
 239
 240 static void txx9wdt_shutdown(struct platform_device *dev)
 241 {
 242         txx9wdt_stop();
 243 }
 244
 245 static struct platform_driver txx9wdt_driver = {
 246         .remove = __exit_p(txx9wdt_remove),
 247         .shutdown = txx9wdt_shutdown,
 248         .driver = {
 249                 .name = "txx9wdt",
 250                 .owner = THIS_MODULE,
 251         },
 252 };
 253
 254 static int __init watchdog_init(void)
 255 {
 256         return platform_driver_probe(&txx9wdt_driver, txx9wdt_probe);
 257 }
 258
 259 static void __exit watchdog_exit(void)
 260 {
 261         platform_driver_unregister(&txx9wdt_driver);
 262 }
 263
 264 module_init(watchdog_init);
 265 module_exit(watchdog_exit);
 266
 267 MODULE_DESCRIPTION("TXx9 Watchdog Driver");
 268 MODULE_LICENSE("GPL");
 269 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 270 MODULE_ALIAS("platform:txx9wdt");