drivers/watchdog/nuc900_wdt.c

   1 /*
   2  * Copyright (c) 2009 Nuvoton technology corporation.
   3  *
   4  * Wan ZongShun <mcuos.com@gmail.com>
   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 as published by
   8  * the Free Software Foundation;version 2 of the License.
   9  *
  10  */
  11
  12 #include <linux/bitops.h>
  13 #include <linux/errno.h>
  14 #include <linux/fs.h>
  15 #include <linux/init.h>
  16 #include <linux/io.h>
  17 #include <linux/clk.h>
  18 #include <linux/kernel.h>
  19 #include <linux/miscdevice.h>
  20 #include <linux/module.h>
  21 #include <linux/moduleparam.h>
  22 #include <linux/platform_device.h>
  23 #include <linux/slab.h>
  24 #include <linux/interrupt.h>
  25 #include <linux/types.h>
  26 #include <linux/watchdog.h>
  27 #include <linux/uaccess.h>
  28
  29 #define REG_WTCR                0x1c
  30 #define WTCLK                   (0x01 << 10)
  31 #define WTE                     (0x01 << 7)     /*wdt enable*/
  32 #define WTIS                    (0x03 << 4)
  33 #define WTIF                    (0x01 << 3)
  34 #define WTRF                    (0x01 << 2)
  35 #define WTRE                    (0x01 << 1)
  36 #define WTR                     (0x01 << 0)
  37 /*
  38  * The watchdog time interval can be calculated via following formula:
  39  * WTIS         real time interval (formula)
  40  * 0x00         ((2^ 14 ) * ((external crystal freq) / 256))seconds
  41  * 0x01         ((2^ 16 ) * ((external crystal freq) / 256))seconds
  42  * 0x02         ((2^ 18 ) * ((external crystal freq) / 256))seconds
  43  * 0x03         ((2^ 20 ) * ((external crystal freq) / 256))seconds
  44  *
  45  * The external crystal freq is 15Mhz in the nuc900 evaluation board.
  46  * So 0x00 = +-0.28 seconds, 0x01 = +-1.12 seconds, 0x02 = +-4.48 seconds,
  47  * 0x03 = +- 16.92 seconds..
  48  */
  49 #define WDT_HW_TIMEOUT          0x02
  50 #define WDT_TIMEOUT             (HZ/2)
  51 #define WDT_HEARTBEAT           15
  52
  53 static int heartbeat = WDT_HEARTBEAT;
  54 module_param(heartbeat, int, 0);
  55 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. "
  56         "(default = " __MODULE_STRING(WDT_HEARTBEAT) ")");
  57
  58 static bool nowayout = WATCHDOG_NOWAYOUT;
  59 module_param(nowayout, bool, 0);
  60 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
  61         "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  62
  63 struct nuc900_wdt {
  64         struct resource  *res;
  65         struct clk       *wdt_clock;
  66         struct platform_device *pdev;
  67         void __iomem     *wdt_base;
  68         char             expect_close;
  69         struct timer_list timer;
  70         spinlock_t       wdt_lock;
  71         unsigned long next_heartbeat;
  72 };
  73
  74 static unsigned long nuc900wdt_busy;
  75 static struct nuc900_wdt *nuc900_wdt;
  76
  77 static inline void nuc900_wdt_keepalive(void)
  78 {
  79         unsigned int val;
  80
  81         spin_lock(&nuc900_wdt->wdt_lock);
  82
  83         val = __raw_readl(nuc900_wdt->wdt_base + REG_WTCR);
  84         val |= (WTR | WTIF);
  85         __raw_writel(val, nuc900_wdt->wdt_base + REG_WTCR);
  86
  87         spin_unlock(&nuc900_wdt->wdt_lock);
  88 }
  89
  90 static inline void nuc900_wdt_start(void)
  91 {
  92         unsigned int val;
  93
  94         spin_lock(&nuc900_wdt->wdt_lock);
  95
  96         val = __raw_readl(nuc900_wdt->wdt_base + REG_WTCR);
  97         val |= (WTRE | WTE | WTR | WTCLK | WTIF);
  98         val &= ~WTIS;
  99         val |= (WDT_HW_TIMEOUT << 0x04);
 100         __raw_writel(val, nuc900_wdt->wdt_base + REG_WTCR);
 101
 102         spin_unlock(&nuc900_wdt->wdt_lock);
 103
 104         nuc900_wdt->next_heartbeat = jiffies + heartbeat * HZ;
 105         mod_timer(&nuc900_wdt->timer, jiffies + WDT_TIMEOUT);
 106 }
 107
 108 static inline void nuc900_wdt_stop(void)
 109 {
 110         unsigned int val;
 111
 112         del_timer(&nuc900_wdt->timer);
 113
 114         spin_lock(&nuc900_wdt->wdt_lock);
 115
 116         val = __raw_readl(nuc900_wdt->wdt_base + REG_WTCR);
 117         val &= ~WTE;
 118         __raw_writel(val, nuc900_wdt->wdt_base + REG_WTCR);
 119
 120         spin_unlock(&nuc900_wdt->wdt_lock);
 121 }
 122
 123 static inline void nuc900_wdt_ping(void)
 124 {
 125         nuc900_wdt->next_heartbeat = jiffies + heartbeat * HZ;
 126 }
 127
 128 static int nuc900_wdt_open(struct inode *inode, struct file *file)
 129 {
 130
 131         if (test_and_set_bit(0, &nuc900wdt_busy))
 132                 return -EBUSY;
 133
 134         nuc900_wdt_start();
 135
 136         return nonseekable_open(inode, file);
 137 }
 138
 139 static int nuc900_wdt_close(struct inode *inode, struct file *file)
 140 {
 141         if (nuc900_wdt->expect_close == 42)
 142                 nuc900_wdt_stop();
 143         else {
 144                 dev_crit(&nuc900_wdt->pdev->dev,
 145                         "Unexpected close, not stopping watchdog!\n");
 146                 nuc900_wdt_ping();
 147         }
 148
 149         nuc900_wdt->expect_close = 0;
 150         clear_bit(0, &nuc900wdt_busy);
 151         return 0;
 152 }
 153
 154 static const struct watchdog_info nuc900_wdt_info = {
 155         .identity       = "nuc900 watchdog",
 156         .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
 157                                                 WDIOF_MAGICCLOSE,
 158 };
 159
 160 static long nuc900_wdt_ioctl(struct file *file,
 161                                         unsigned int cmd, unsigned long arg)
 162 {
 163         void __user *argp = (void __user *)arg;
 164         int __user *p = argp;
 165         int new_value;
 166
 167         switch (cmd) {
 168         case WDIOC_GETSUPPORT:
 169                 return copy_to_user(argp, &nuc900_wdt_info,
 170                                 sizeof(nuc900_wdt_info)) ? -EFAULT : 0;
 171         case WDIOC_GETSTATUS:
 172         case WDIOC_GETBOOTSTATUS:
 173                 return put_user(0, p);
 174
 175         case WDIOC_KEEPALIVE:
 176                 nuc900_wdt_ping();
 177                 return 0;
 178
 179         case WDIOC_SETTIMEOUT:
 180                 if (get_user(new_value, p))
 181                         return -EFAULT;
 182
 183                 heartbeat = new_value;
 184                 nuc900_wdt_ping();
 185
 186                 return put_user(new_value, p);
 187         case WDIOC_GETTIMEOUT:
 188                 return put_user(heartbeat, p);
 189         default:
 190                 return -ENOTTY;
 191         }
 192 }
 193
 194 static ssize_t nuc900_wdt_write(struct file *file, const char __user *data,
 195                                                 size_t len, loff_t *ppos)
 196 {
 197         if (!len)
 198                 return 0;
 199
 200         /* Scan for magic character */
 201         if (!nowayout) {
 202                 size_t i;
 203
 204                 nuc900_wdt->expect_close = 0;
 205
 206                 for (i = 0; i < len; i++) {
 207                         char c;
 208                         if (get_user(c, data + i))
 209                                 return -EFAULT;
 210                         if (c == 'V') {
 211                                 nuc900_wdt->expect_close = 42;
 212                                 break;
 213                         }
 214                 }
 215         }
 216
 217         nuc900_wdt_ping();
 218         return len;
 219 }
 220
 221 static void nuc900_wdt_timer_ping(unsigned long data)
 222 {
 223         if (time_before(jiffies, nuc900_wdt->next_heartbeat)) {
 224                 nuc900_wdt_keepalive();
 225                 mod_timer(&nuc900_wdt->timer, jiffies + WDT_TIMEOUT);
 226         } else
 227                 dev_warn(&nuc900_wdt->pdev->dev, "Will reset the machine !\n");
 228 }
 229
 230 static const struct file_operations nuc900wdt_fops = {
 231         .owner          = THIS_MODULE,
 232         .llseek         = no_llseek,
 233         .unlocked_ioctl = nuc900_wdt_ioctl,
 234         .open           = nuc900_wdt_open,
 235         .release        = nuc900_wdt_close,
 236         .write          = nuc900_wdt_write,
 237 };
 238
 239 static struct miscdevice nuc900wdt_miscdev = {
 240         .minor          = WATCHDOG_MINOR,
 241         .name           = "watchdog",
 242         .fops           = &nuc900wdt_fops,
 243 };
 244
 245 static int nuc900wdt_probe(struct platform_device *pdev)
 246 {
 247         int ret = 0;
 248
 249         nuc900_wdt = kzalloc(sizeof(struct nuc900_wdt), GFP_KERNEL);
 250         if (!nuc900_wdt)
 251                 return -ENOMEM;
 252
 253         nuc900_wdt->pdev = pdev;
 254
 255         spin_lock_init(&nuc900_wdt->wdt_lock);
 256
 257         nuc900_wdt->res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 258         if (nuc900_wdt->res == NULL) {
 259                 dev_err(&pdev->dev, "no memory resource specified\n");
 260                 ret = -ENOENT;
 261                 goto err_get;
 262         }
 263
 264         if (!request_mem_region(nuc900_wdt->res->start,
 265                                 resource_size(nuc900_wdt->res), pdev->name)) {
 266                 dev_err(&pdev->dev, "failed to get memory region\n");
 267                 ret = -ENOENT;
 268                 goto err_get;
 269         }
 270
 271         nuc900_wdt->wdt_base = ioremap(nuc900_wdt->res->start,
 272                                         resource_size(nuc900_wdt->res));
 273         if (nuc900_wdt->wdt_base == NULL) {
 274                 dev_err(&pdev->dev, "failed to ioremap() region\n");
 275                 ret = -EINVAL;
 276                 goto err_req;
 277         }
 278
 279         nuc900_wdt->wdt_clock = clk_get(&pdev->dev, NULL);
 280         if (IS_ERR(nuc900_wdt->wdt_clock)) {
 281                 dev_err(&pdev->dev, "failed to find watchdog clock source\n");
 282                 ret = PTR_ERR(nuc900_wdt->wdt_clock);
 283                 goto err_map;
 284         }
 285
 286         clk_enable(nuc900_wdt->wdt_clock);
 287
 288         setup_timer(&nuc900_wdt->timer, nuc900_wdt_timer_ping, 0);
 289
 290         ret = misc_register(&nuc900wdt_miscdev);
 291         if (ret) {
 292                 dev_err(&pdev->dev, "err register miscdev on minor=%d (%d)\n",
 293                         WATCHDOG_MINOR, ret);
 294                 goto err_clk;
 295         }
 296
 297         return 0;
 298
 299 err_clk:
 300         clk_disable(nuc900_wdt->wdt_clock);
 301         clk_put(nuc900_wdt->wdt_clock);
 302 err_map:
 303         iounmap(nuc900_wdt->wdt_base);
 304 err_req:
 305         release_mem_region(nuc900_wdt->res->start,
 306                                         resource_size(nuc900_wdt->res));
 307 err_get:
 308         kfree(nuc900_wdt);
 309         return ret;
 310 }
 311
 312 static int nuc900wdt_remove(struct platform_device *pdev)
 313 {
 314         misc_deregister(&nuc900wdt_miscdev);
 315
 316         clk_disable(nuc900_wdt->wdt_clock);
 317         clk_put(nuc900_wdt->wdt_clock);
 318
 319         iounmap(nuc900_wdt->wdt_base);
 320
 321         release_mem_region(nuc900_wdt->res->start,
 322                                         resource_size(nuc900_wdt->res));
 323
 324         kfree(nuc900_wdt);
 325
 326         return 0;
 327 }
 328
 329 static struct platform_driver nuc900wdt_driver = {
 330         .probe          = nuc900wdt_probe,
 331         .remove         = nuc900wdt_remove,
 332         .driver         = {
 333                 .name   = "nuc900-wdt",
 334                 .owner  = THIS_MODULE,
 335         },
 336 };
 337
 338 module_platform_driver(nuc900wdt_driver);
 339
 340 MODULE_AUTHOR("Wan ZongShun <mcuos.com@gmail.com>");
 341 MODULE_DESCRIPTION("Watchdog driver for NUC900");
 342 MODULE_LICENSE("GPL");
 343 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 344 MODULE_ALIAS("platform:nuc900-wdt");