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 clk       *wdt_clock;
  65         struct platform_device *pdev;
  66         void __iomem     *wdt_base;
  67         char             expect_close;
  68         struct timer_list timer;
  69         spinlock_t       wdt_lock;
  70         unsigned long next_heartbeat;
  71 };
  72
  73 static unsigned long nuc900wdt_busy;
  74 static struct nuc900_wdt *nuc900_wdt;
  75
  76 static inline void nuc900_wdt_keepalive(void)
  77 {
  78         unsigned int val;
  79
  80         spin_lock(&nuc900_wdt->wdt_lock);
  81
  82         val = __raw_readl(nuc900_wdt->wdt_base + REG_WTCR);
  83         val |= (WTR | WTIF);
  84         __raw_writel(val, nuc900_wdt->wdt_base + REG_WTCR);
  85
  86         spin_unlock(&nuc900_wdt->wdt_lock);
  87 }
  88
  89 static inline void nuc900_wdt_start(void)
  90 {
  91         unsigned int val;
  92
  93         spin_lock(&nuc900_wdt->wdt_lock);
  94
  95         val = __raw_readl(nuc900_wdt->wdt_base + REG_WTCR);
  96         val |= (WTRE | WTE | WTR | WTCLK | WTIF);
  97         val &= ~WTIS;
  98         val |= (WDT_HW_TIMEOUT << 0x04);
  99         __raw_writel(val, nuc900_wdt->wdt_base + REG_WTCR);
 100
 101         spin_unlock(&nuc900_wdt->wdt_lock);
 102
 103         nuc900_wdt->next_heartbeat = jiffies + heartbeat * HZ;
 104         mod_timer(&nuc900_wdt->timer, jiffies + WDT_TIMEOUT);
 105 }
 106
 107 static inline void nuc900_wdt_stop(void)
 108 {
 109         unsigned int val;
 110
 111         del_timer(&nuc900_wdt->timer);
 112
 113         spin_lock(&nuc900_wdt->wdt_lock);
 114
 115         val = __raw_readl(nuc900_wdt->wdt_base + REG_WTCR);
 116         val &= ~WTE;
 117         __raw_writel(val, nuc900_wdt->wdt_base + REG_WTCR);
 118
 119         spin_unlock(&nuc900_wdt->wdt_lock);
 120 }
 121
 122 static inline void nuc900_wdt_ping(void)
 123 {
 124         nuc900_wdt->next_heartbeat = jiffies + heartbeat * HZ;
 125 }
 126
 127 static int nuc900_wdt_open(struct inode *inode, struct file *file)
 128 {
 129
 130         if (test_and_set_bit(0, &nuc900wdt_busy))
 131                 return -EBUSY;
 132
 133         nuc900_wdt_start();
 134
 135         return nonseekable_open(inode, file);
 136 }
 137
 138 static int nuc900_wdt_close(struct inode *inode, struct file *file)
 139 {
 140         if (nuc900_wdt->expect_close == 42)
 141                 nuc900_wdt_stop();
 142         else {
 143                 dev_crit(&nuc900_wdt->pdev->dev,
 144                         "Unexpected close, not stopping watchdog!\n");
 145                 nuc900_wdt_ping();
 146         }
 147
 148         nuc900_wdt->expect_close = 0;
 149         clear_bit(0, &nuc900wdt_busy);
 150         return 0;
 151 }
 152
 153 static const struct watchdog_info nuc900_wdt_info = {
 154         .identity       = "nuc900 watchdog",
 155         .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
 156                                                 WDIOF_MAGICCLOSE,
 157 };
 158
 159 static long nuc900_wdt_ioctl(struct file *file,
 160                                         unsigned int cmd, unsigned long arg)
 161 {
 162         void __user *argp = (void __user *)arg;
 163         int __user *p = argp;
 164         int new_value;
 165
 166         switch (cmd) {
 167         case WDIOC_GETSUPPORT:
 168                 return copy_to_user(argp, &nuc900_wdt_info,
 169                                 sizeof(nuc900_wdt_info)) ? -EFAULT : 0;
 170         case WDIOC_GETSTATUS:
 171         case WDIOC_GETBOOTSTATUS:
 172                 return put_user(0, p);
 173
 174         case WDIOC_KEEPALIVE:
 175                 nuc900_wdt_ping();
 176                 return 0;
 177
 178         case WDIOC_SETTIMEOUT:
 179                 if (get_user(new_value, p))
 180                         return -EFAULT;
 181
 182                 heartbeat = new_value;
 183                 nuc900_wdt_ping();
 184
 185                 return put_user(new_value, p);
 186         case WDIOC_GETTIMEOUT:
 187                 return put_user(heartbeat, p);
 188         default:
 189                 return -ENOTTY;
 190         }
 191 }
 192
 193 static ssize_t nuc900_wdt_write(struct file *file, const char __user *data,
 194                                                 size_t len, loff_t *ppos)
 195 {
 196         if (!len)
 197                 return 0;
 198
 199         /* Scan for magic character */
 200         if (!nowayout) {
 201                 size_t i;
 202
 203                 nuc900_wdt->expect_close = 0;
 204
 205                 for (i = 0; i < len; i++) {
 206                         char c;
 207                         if (get_user(c, data + i))
 208                                 return -EFAULT;
 209                         if (c == 'V') {
 210                                 nuc900_wdt->expect_close = 42;
 211                                 break;
 212                         }
 213                 }
 214         }
 215
 216         nuc900_wdt_ping();
 217         return len;
 218 }
 219
 220 static void nuc900_wdt_timer_ping(unsigned long data)
 221 {
 222         if (time_before(jiffies, nuc900_wdt->next_heartbeat)) {
 223                 nuc900_wdt_keepalive();
 224                 mod_timer(&nuc900_wdt->timer, jiffies + WDT_TIMEOUT);
 225         } else
 226                 dev_warn(&nuc900_wdt->pdev->dev, "Will reset the machine !\n");
 227 }
 228
 229 static const struct file_operations nuc900wdt_fops = {
 230         .owner          = THIS_MODULE,
 231         .llseek         = no_llseek,
 232         .unlocked_ioctl = nuc900_wdt_ioctl,
 233         .open           = nuc900_wdt_open,
 234         .release        = nuc900_wdt_close,
 235         .write          = nuc900_wdt_write,
 236 };
 237
 238 static struct miscdevice nuc900wdt_miscdev = {
 239         .minor          = WATCHDOG_MINOR,
 240         .name           = "watchdog",
 241         .fops           = &nuc900wdt_fops,
 242 };
 243
 244 static int nuc900wdt_probe(struct platform_device *pdev)
 245 {
 246         struct resource *res;
 247         int ret = 0;
 248
 249         nuc900_wdt = devm_kzalloc(&pdev->dev, sizeof(*nuc900_wdt),
 250                                 GFP_KERNEL);
 251         if (!nuc900_wdt)
 252                 return -ENOMEM;
 253
 254         nuc900_wdt->pdev = pdev;
 255
 256         spin_lock_init(&nuc900_wdt->wdt_lock);
 257
 258         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 259         nuc900_wdt->wdt_base = devm_ioremap_resource(&pdev->dev, res);
 260         if (IS_ERR(nuc900_wdt->wdt_base))
 261                 return PTR_ERR(nuc900_wdt->wdt_base);
 262
 263         nuc900_wdt->wdt_clock = devm_clk_get(&pdev->dev, NULL);
 264         if (IS_ERR(nuc900_wdt->wdt_clock)) {
 265                 dev_err(&pdev->dev, "failed to find watchdog clock source\n");
 266                 return PTR_ERR(nuc900_wdt->wdt_clock);
 267         }
 268
 269         clk_enable(nuc900_wdt->wdt_clock);
 270
 271         setup_timer(&nuc900_wdt->timer, nuc900_wdt_timer_ping, 0);
 272
 273         ret = misc_register(&nuc900wdt_miscdev);
 274         if (ret) {
 275                 dev_err(&pdev->dev, "err register miscdev on minor=%d (%d)\n",
 276                         WATCHDOG_MINOR, ret);
 277                 goto err_clk;
 278         }
 279
 280         return 0;
 281
 282 err_clk:
 283         clk_disable(nuc900_wdt->wdt_clock);
 284         return ret;
 285 }
 286
 287 static int nuc900wdt_remove(struct platform_device *pdev)
 288 {
 289         misc_deregister(&nuc900wdt_miscdev);
 290
 291         clk_disable(nuc900_wdt->wdt_clock);
 292
 293         return 0;
 294 }
 295
 296 static struct platform_driver nuc900wdt_driver = {
 297         .probe          = nuc900wdt_probe,
 298         .remove         = nuc900wdt_remove,
 299         .driver         = {
 300                 .name   = "nuc900-wdt",
 301                 .owner  = THIS_MODULE,
 302         },
 303 };
 304
 305 module_platform_driver(nuc900wdt_driver);
 306
 307 MODULE_AUTHOR("Wan ZongShun <mcuos.com@gmail.com>");
 308 MODULE_DESCRIPTION("Watchdog driver for NUC900");
 309 MODULE_LICENSE("GPL");
 310 MODULE_ALIAS("platform:nuc900-wdt");