drivers/watchdog/nuc900_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (c) 2009 Nuvoton technology corporation.
   4  *
   5  * Wan ZongShun <mcuos.com@gmail.com>
   6  */
   7
   8 #include <linux/bitops.h>
   9 #include <linux/errno.h>
  10 #include <linux/fs.h>
  11 #include <linux/io.h>
  12 #include <linux/clk.h>
  13 #include <linux/kernel.h>
  14 #include <linux/miscdevice.h>
  15 #include <linux/module.h>
  16 #include <linux/moduleparam.h>
  17 #include <linux/platform_device.h>
  18 #include <linux/slab.h>
  19 #include <linux/interrupt.h>
  20 #include <linux/types.h>
  21 #include <linux/watchdog.h>
  22 #include <linux/uaccess.h>
  23
  24 #define REG_WTCR                0x1c
  25 #define WTCLK                   (0x01 << 10)
  26 #define WTE                     (0x01 << 7)     /*wdt enable*/
  27 #define WTIS                    (0x03 << 4)
  28 #define WTIF                    (0x01 << 3)
  29 #define WTRF                    (0x01 << 2)
  30 #define WTRE                    (0x01 << 1)
  31 #define WTR                     (0x01 << 0)
  32 /*
  33  * The watchdog time interval can be calculated via following formula:
  34  * WTIS         real time interval (formula)
  35  * 0x00         ((2^ 14 ) * ((external crystal freq) / 256))seconds
  36  * 0x01         ((2^ 16 ) * ((external crystal freq) / 256))seconds
  37  * 0x02         ((2^ 18 ) * ((external crystal freq) / 256))seconds
  38  * 0x03         ((2^ 20 ) * ((external crystal freq) / 256))seconds
  39  *
  40  * The external crystal freq is 15Mhz in the nuc900 evaluation board.
  41  * So 0x00 = +-0.28 seconds, 0x01 = +-1.12 seconds, 0x02 = +-4.48 seconds,
  42  * 0x03 = +- 16.92 seconds..
  43  */
  44 #define WDT_HW_TIMEOUT          0x02
  45 #define WDT_TIMEOUT             (HZ/2)
  46 #define WDT_HEARTBEAT           15
  47
  48 static int heartbeat = WDT_HEARTBEAT;
  49 module_param(heartbeat, int, 0);
  50 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. "
  51         "(default = " __MODULE_STRING(WDT_HEARTBEAT) ")");
  52
  53 static bool nowayout = WATCHDOG_NOWAYOUT;
  54 module_param(nowayout, bool, 0);
  55 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
  56         "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  57
  58 struct nuc900_wdt {
  59         struct clk       *wdt_clock;
  60         struct platform_device *pdev;
  61         void __iomem     *wdt_base;
  62         char             expect_close;
  63         struct timer_list timer;
  64         spinlock_t       wdt_lock;
  65         unsigned long next_heartbeat;
  66 };
  67
  68 static unsigned long nuc900wdt_busy;
  69 static struct nuc900_wdt *nuc900_wdt;
  70
  71 static inline void nuc900_wdt_keepalive(void)
  72 {
  73         unsigned int val;
  74
  75         spin_lock(&nuc900_wdt->wdt_lock);
  76
  77         val = __raw_readl(nuc900_wdt->wdt_base + REG_WTCR);
  78         val |= (WTR | WTIF);
  79         __raw_writel(val, nuc900_wdt->wdt_base + REG_WTCR);
  80
  81         spin_unlock(&nuc900_wdt->wdt_lock);
  82 }
  83
  84 static inline void nuc900_wdt_start(void)
  85 {
  86         unsigned int val;
  87
  88         spin_lock(&nuc900_wdt->wdt_lock);
  89
  90         val = __raw_readl(nuc900_wdt->wdt_base + REG_WTCR);
  91         val |= (WTRE | WTE | WTR | WTCLK | WTIF);
  92         val &= ~WTIS;
  93         val |= (WDT_HW_TIMEOUT << 0x04);
  94         __raw_writel(val, nuc900_wdt->wdt_base + REG_WTCR);
  95
  96         spin_unlock(&nuc900_wdt->wdt_lock);
  97
  98         nuc900_wdt->next_heartbeat = jiffies + heartbeat * HZ;
  99         mod_timer(&nuc900_wdt->timer, jiffies + WDT_TIMEOUT);
 100 }
 101
 102 static inline void nuc900_wdt_stop(void)
 103 {
 104         unsigned int val;
 105
 106         del_timer(&nuc900_wdt->timer);
 107
 108         spin_lock(&nuc900_wdt->wdt_lock);
 109
 110         val = __raw_readl(nuc900_wdt->wdt_base + REG_WTCR);
 111         val &= ~WTE;
 112         __raw_writel(val, nuc900_wdt->wdt_base + REG_WTCR);
 113
 114         spin_unlock(&nuc900_wdt->wdt_lock);
 115 }
 116
 117 static inline void nuc900_wdt_ping(void)
 118 {
 119         nuc900_wdt->next_heartbeat = jiffies + heartbeat * HZ;
 120 }
 121
 122 static int nuc900_wdt_open(struct inode *inode, struct file *file)
 123 {
 124
 125         if (test_and_set_bit(0, &nuc900wdt_busy))
 126                 return -EBUSY;
 127
 128         nuc900_wdt_start();
 129
 130         return stream_open(inode, file);
 131 }
 132
 133 static int nuc900_wdt_close(struct inode *inode, struct file *file)
 134 {
 135         if (nuc900_wdt->expect_close == 42)
 136                 nuc900_wdt_stop();
 137         else {
 138                 dev_crit(&nuc900_wdt->pdev->dev,
 139                         "Unexpected close, not stopping watchdog!\n");
 140                 nuc900_wdt_ping();
 141         }
 142
 143         nuc900_wdt->expect_close = 0;
 144         clear_bit(0, &nuc900wdt_busy);
 145         return 0;
 146 }
 147
 148 static const struct watchdog_info nuc900_wdt_info = {
 149         .identity       = "nuc900 watchdog",
 150         .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
 151                                                 WDIOF_MAGICCLOSE,
 152 };
 153
 154 static long nuc900_wdt_ioctl(struct file *file,
 155                                         unsigned int cmd, unsigned long arg)
 156 {
 157         void __user *argp = (void __user *)arg;
 158         int __user *p = argp;
 159         int new_value;
 160
 161         switch (cmd) {
 162         case WDIOC_GETSUPPORT:
 163                 return copy_to_user(argp, &nuc900_wdt_info,
 164                                 sizeof(nuc900_wdt_info)) ? -EFAULT : 0;
 165         case WDIOC_GETSTATUS:
 166         case WDIOC_GETBOOTSTATUS:
 167                 return put_user(0, p);
 168
 169         case WDIOC_KEEPALIVE:
 170                 nuc900_wdt_ping();
 171                 return 0;
 172
 173         case WDIOC_SETTIMEOUT:
 174                 if (get_user(new_value, p))
 175                         return -EFAULT;
 176
 177                 heartbeat = new_value;
 178                 nuc900_wdt_ping();
 179
 180                 return put_user(new_value, p);
 181         case WDIOC_GETTIMEOUT:
 182                 return put_user(heartbeat, p);
 183         default:
 184                 return -ENOTTY;
 185         }
 186 }
 187
 188 static ssize_t nuc900_wdt_write(struct file *file, const char __user *data,
 189                                                 size_t len, loff_t *ppos)
 190 {
 191         if (!len)
 192                 return 0;
 193
 194         /* Scan for magic character */
 195         if (!nowayout) {
 196                 size_t i;
 197
 198                 nuc900_wdt->expect_close = 0;
 199
 200                 for (i = 0; i < len; i++) {
 201                         char c;
 202                         if (get_user(c, data + i))
 203                                 return -EFAULT;
 204                         if (c == 'V') {
 205                                 nuc900_wdt->expect_close = 42;
 206                                 break;
 207                         }
 208                 }
 209         }
 210
 211         nuc900_wdt_ping();
 212         return len;
 213 }
 214
 215 static void nuc900_wdt_timer_ping(struct timer_list *unused)
 216 {
 217         if (time_before(jiffies, nuc900_wdt->next_heartbeat)) {
 218                 nuc900_wdt_keepalive();
 219                 mod_timer(&nuc900_wdt->timer, jiffies + WDT_TIMEOUT);
 220         } else
 221                 dev_warn(&nuc900_wdt->pdev->dev, "Will reset the machine !\n");
 222 }
 223
 224 static const struct file_operations nuc900wdt_fops = {
 225         .owner          = THIS_MODULE,
 226         .llseek         = no_llseek,
 227         .unlocked_ioctl = nuc900_wdt_ioctl,
 228         .open           = nuc900_wdt_open,
 229         .release        = nuc900_wdt_close,
 230         .write          = nuc900_wdt_write,
 231 };
 232
 233 static struct miscdevice nuc900wdt_miscdev = {
 234         .minor          = WATCHDOG_MINOR,
 235         .name           = "watchdog",
 236         .fops           = &nuc900wdt_fops,
 237 };
 238
 239 static int nuc900wdt_probe(struct platform_device *pdev)
 240 {
 241         int ret = 0;
 242
 243         nuc900_wdt = devm_kzalloc(&pdev->dev, sizeof(*nuc900_wdt),
 244                                 GFP_KERNEL);
 245         if (!nuc900_wdt)
 246                 return -ENOMEM;
 247
 248         nuc900_wdt->pdev = pdev;
 249
 250         spin_lock_init(&nuc900_wdt->wdt_lock);
 251
 252         nuc900_wdt->wdt_base = devm_platform_ioremap_resource(pdev, 0);
 253         if (IS_ERR(nuc900_wdt->wdt_base))
 254                 return PTR_ERR(nuc900_wdt->wdt_base);
 255
 256         nuc900_wdt->wdt_clock = devm_clk_get(&pdev->dev, NULL);
 257         if (IS_ERR(nuc900_wdt->wdt_clock)) {
 258                 dev_err(&pdev->dev, "failed to find watchdog clock source\n");
 259                 return PTR_ERR(nuc900_wdt->wdt_clock);
 260         }
 261
 262         clk_enable(nuc900_wdt->wdt_clock);
 263
 264         timer_setup(&nuc900_wdt->timer, nuc900_wdt_timer_ping, 0);
 265
 266         ret = misc_register(&nuc900wdt_miscdev);
 267         if (ret) {
 268                 dev_err(&pdev->dev, "err register miscdev on minor=%d (%d)\n",
 269                         WATCHDOG_MINOR, ret);
 270                 goto err_clk;
 271         }
 272
 273         return 0;
 274
 275 err_clk:
 276         clk_disable(nuc900_wdt->wdt_clock);
 277         return ret;
 278 }
 279
 280 static int nuc900wdt_remove(struct platform_device *pdev)
 281 {
 282         misc_deregister(&nuc900wdt_miscdev);
 283
 284         clk_disable(nuc900_wdt->wdt_clock);
 285
 286         return 0;
 287 }
 288
 289 static struct platform_driver nuc900wdt_driver = {
 290         .probe          = nuc900wdt_probe,
 291         .remove         = nuc900wdt_remove,
 292         .driver         = {
 293                 .name   = "nuc900-wdt",
 294         },
 295 };
 296
 297 module_platform_driver(nuc900wdt_driver);
 298
 299 MODULE_AUTHOR("Wan ZongShun <mcuos.com@gmail.com>");
 300 MODULE_DESCRIPTION("Watchdog driver for NUC900");
 301 MODULE_LICENSE("GPL");
 302 MODULE_ALIAS("platform:nuc900-wdt");