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