drivers/watchdog/rc32434_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  IDT Interprise 79RC32434 watchdog driver
   4  *
   5  *  Copyright (C) 2006, Ondrej Zajicek <santiago@crfreenet.org>
   6  *  Copyright (C) 2008, Florian Fainelli <florian@openwrt.org>
   7  *
   8  *  based on
   9  *  SoftDog 0.05:       A Software Watchdog Device
  10  *
  11  *  (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
  12  *                                      All Rights Reserved.
  13  */
  14
  15 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  16
  17 #include <linux/module.h>               /* For module specific items */
  18 #include <linux/moduleparam.h>          /* For new moduleparam's */
  19 #include <linux/types.h>                /* For standard types (like size_t) */
  20 #include <linux/errno.h>                /* For the -ENODEV/... values */
  21 #include <linux/kernel.h>               /* For printk/panic/... */
  22 #include <linux/fs.h>                   /* For file operations */
  23 #include <linux/miscdevice.h>           /* For struct miscdevice */
  24 #include <linux/watchdog.h>             /* For the watchdog specific items */
  25 #include <linux/init.h>                 /* For __init/__exit/... */
  26 #include <linux/platform_device.h>      /* For platform_driver framework */
  27 #include <linux/spinlock.h>             /* For spin_lock/spin_unlock/... */
  28 #include <linux/uaccess.h>              /* For copy_to_user/put_user/... */
  29 #include <linux/io.h>                   /* For devm_ioremap */
  30
  31 #include <asm/mach-rc32434/integ.h>     /* For the Watchdog registers */
  32
  33 #define VERSION "1.0"
  34
  35 static struct {
  36         unsigned long inuse;
  37         spinlock_t io_lock;
  38 } rc32434_wdt_device;
  39
  40 static struct integ __iomem *wdt_reg;
  41
  42 static int expect_close;
  43
  44 /* Board internal clock speed in Hz,
  45  * the watchdog timer ticks at. */
  46 extern unsigned int idt_cpu_freq;
  47
  48 /* translate wtcompare value to seconds and vice versa */
  49 #define WTCOMP2SEC(x)   (x / idt_cpu_freq)
  50 #define SEC2WTCOMP(x)   (x * idt_cpu_freq)
  51
  52 /* Use a default timeout of 20s. This should be
  53  * safe for CPU clock speeds up to 400MHz, as
  54  * ((2 ^ 32) - 1) / (400MHz / 2) = 21s.  */
  55 #define WATCHDOG_TIMEOUT 20
  56
  57 static int timeout = WATCHDOG_TIMEOUT;
  58 module_param(timeout, int, 0);
  59 MODULE_PARM_DESC(timeout, "Watchdog timeout value, in seconds (default="
  60                 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
  61
  62 static bool nowayout = WATCHDOG_NOWAYOUT;
  63 module_param(nowayout, bool, 0);
  64 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  65         __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  66
  67 /* apply or and nand masks to data read from addr and write back */
  68 #define SET_BITS(addr, or, nand) \
  69         writel((readl(&addr) | or) & ~nand, &addr)
  70
  71 static int rc32434_wdt_set(int new_timeout)
  72 {
  73         int max_to = WTCOMP2SEC((u32)-1);
  74
  75         if (new_timeout < 0 || new_timeout > max_to) {
  76                 pr_err("timeout value must be between 0 and %d\n", max_to);
  77                 return -EINVAL;
  78         }
  79         timeout = new_timeout;
  80         spin_lock(&rc32434_wdt_device.io_lock);
  81         writel(SEC2WTCOMP(timeout), &wdt_reg->wtcompare);
  82         spin_unlock(&rc32434_wdt_device.io_lock);
  83
  84         return 0;
  85 }
  86
  87 static void rc32434_wdt_start(void)
  88 {
  89         u32 or, nand;
  90
  91         spin_lock(&rc32434_wdt_device.io_lock);
  92
  93         /* zero the counter before enabling */
  94         writel(0, &wdt_reg->wtcount);
  95
  96         /* don't generate a non-maskable interrupt,
  97          * do a warm reset instead */
  98         nand = 1 << RC32434_ERR_WNE;
  99         or = 1 << RC32434_ERR_WRE;
 100
 101         /* reset the ERRCS timeout bit in case it's set */
 102         nand |= 1 << RC32434_ERR_WTO;
 103
 104         SET_BITS(wdt_reg->errcs, or, nand);
 105
 106         /* set the timeout (either default or based on module param) */
 107         rc32434_wdt_set(timeout);
 108
 109         /* reset WTC timeout bit and enable WDT */
 110         nand = 1 << RC32434_WTC_TO;
 111         or = 1 << RC32434_WTC_EN;
 112
 113         SET_BITS(wdt_reg->wtc, or, nand);
 114
 115         spin_unlock(&rc32434_wdt_device.io_lock);
 116         pr_info("Started watchdog timer\n");
 117 }
 118
 119 static void rc32434_wdt_stop(void)
 120 {
 121         spin_lock(&rc32434_wdt_device.io_lock);
 122
 123         /* Disable WDT */
 124         SET_BITS(wdt_reg->wtc, 0, 1 << RC32434_WTC_EN);
 125
 126         spin_unlock(&rc32434_wdt_device.io_lock);
 127         pr_info("Stopped watchdog timer\n");
 128 }
 129
 130 static void rc32434_wdt_ping(void)
 131 {
 132         spin_lock(&rc32434_wdt_device.io_lock);
 133         writel(0, &wdt_reg->wtcount);
 134         spin_unlock(&rc32434_wdt_device.io_lock);
 135 }
 136
 137 static int rc32434_wdt_open(struct inode *inode, struct file *file)
 138 {
 139         if (test_and_set_bit(0, &rc32434_wdt_device.inuse))
 140                 return -EBUSY;
 141
 142         if (nowayout)
 143                 __module_get(THIS_MODULE);
 144
 145         rc32434_wdt_start();
 146         rc32434_wdt_ping();
 147
 148         return stream_open(inode, file);
 149 }
 150
 151 static int rc32434_wdt_release(struct inode *inode, struct file *file)
 152 {
 153         if (expect_close == 42) {
 154                 rc32434_wdt_stop();
 155                 module_put(THIS_MODULE);
 156         } else {
 157                 pr_crit("device closed unexpectedly. WDT will not stop!\n");
 158                 rc32434_wdt_ping();
 159         }
 160         clear_bit(0, &rc32434_wdt_device.inuse);
 161         return 0;
 162 }
 163
 164 static ssize_t rc32434_wdt_write(struct file *file, const char *data,
 165                                 size_t len, loff_t *ppos)
 166 {
 167         if (len) {
 168                 if (!nowayout) {
 169                         size_t i;
 170
 171                         /* In case it was set long ago */
 172                         expect_close = 0;
 173
 174                         for (i = 0; i != len; i++) {
 175                                 char c;
 176                                 if (get_user(c, data + i))
 177                                         return -EFAULT;
 178                                 if (c == 'V')
 179                                         expect_close = 42;
 180                         }
 181                 }
 182                 rc32434_wdt_ping();
 183                 return len;
 184         }
 185         return 0;
 186 }
 187
 188 static long rc32434_wdt_ioctl(struct file *file, unsigned int cmd,
 189                                 unsigned long arg)
 190 {
 191         void __user *argp = (void __user *)arg;
 192         int new_timeout;
 193         unsigned int value;
 194         static const struct watchdog_info ident = {
 195                 .options =              WDIOF_SETTIMEOUT |
 196                                         WDIOF_KEEPALIVEPING |
 197                                         WDIOF_MAGICCLOSE,
 198                 .identity =             "RC32434_WDT Watchdog",
 199         };
 200         switch (cmd) {
 201         case WDIOC_GETSUPPORT:
 202                 if (copy_to_user(argp, &ident, sizeof(ident)))
 203                         return -EFAULT;
 204                 break;
 205         case WDIOC_GETSTATUS:
 206         case WDIOC_GETBOOTSTATUS:
 207                 value = 0;
 208                 if (copy_to_user(argp, &value, sizeof(int)))
 209                         return -EFAULT;
 210                 break;
 211         case WDIOC_SETOPTIONS:
 212                 if (copy_from_user(&value, argp, sizeof(int)))
 213                         return -EFAULT;
 214                 switch (value) {
 215                 case WDIOS_ENABLECARD:
 216                         rc32434_wdt_start();
 217                         break;
 218                 case WDIOS_DISABLECARD:
 219                         rc32434_wdt_stop();
 220                         break;
 221                 default:
 222                         return -EINVAL;
 223                 }
 224                 break;
 225         case WDIOC_KEEPALIVE:
 226                 rc32434_wdt_ping();
 227                 break;
 228         case WDIOC_SETTIMEOUT:
 229                 if (copy_from_user(&new_timeout, argp, sizeof(int)))
 230                         return -EFAULT;
 231                 if (rc32434_wdt_set(new_timeout))
 232                         return -EINVAL;
 233                 fallthrough;
 234         case WDIOC_GETTIMEOUT:
 235                 return copy_to_user(argp, &timeout, sizeof(int)) ? -EFAULT : 0;
 236         default:
 237                 return -ENOTTY;
 238         }
 239
 240         return 0;
 241 }
 242
 243 static const struct file_operations rc32434_wdt_fops = {
 244         .owner          = THIS_MODULE,
 245         .llseek         = no_llseek,
 246         .write          = rc32434_wdt_write,
 247         .unlocked_ioctl = rc32434_wdt_ioctl,
 248         .compat_ioctl   = compat_ptr_ioctl,
 249         .open           = rc32434_wdt_open,
 250         .release        = rc32434_wdt_release,
 251 };
 252
 253 static struct miscdevice rc32434_wdt_miscdev = {
 254         .minor  = WATCHDOG_MINOR,
 255         .name   = "watchdog",
 256         .fops   = &rc32434_wdt_fops,
 257 };
 258
 259 static int rc32434_wdt_probe(struct platform_device *pdev)
 260 {
 261         int ret;
 262         struct resource *r;
 263
 264         r = platform_get_resource_byname(pdev, IORESOURCE_MEM, "rb532_wdt_res");
 265         if (!r) {
 266                 pr_err("failed to retrieve resources\n");
 267                 return -ENODEV;
 268         }
 269
 270         wdt_reg = devm_ioremap(&pdev->dev, r->start, resource_size(r));
 271         if (!wdt_reg) {
 272                 pr_err("failed to remap I/O resources\n");
 273                 return -ENXIO;
 274         }
 275
 276         spin_lock_init(&rc32434_wdt_device.io_lock);
 277
 278         /* Make sure the watchdog is not running */
 279         rc32434_wdt_stop();
 280
 281         /* Check that the heartbeat value is within it's range;
 282          * if not reset to the default */
 283         if (rc32434_wdt_set(timeout)) {
 284                 rc32434_wdt_set(WATCHDOG_TIMEOUT);
 285                 pr_info("timeout value must be between 0 and %d\n",
 286                         WTCOMP2SEC((u32)-1));
 287         }
 288
 289         ret = misc_register(&rc32434_wdt_miscdev);
 290         if (ret < 0) {
 291                 pr_err("failed to register watchdog device\n");
 292                 return ret;
 293         }
 294
 295         pr_info("Watchdog Timer version " VERSION ", timer margin: %d sec\n",
 296                 timeout);
 297
 298         return 0;
 299 }
 300
 301 static int rc32434_wdt_remove(struct platform_device *pdev)
 302 {
 303         misc_deregister(&rc32434_wdt_miscdev);
 304         return 0;
 305 }
 306
 307 static void rc32434_wdt_shutdown(struct platform_device *pdev)
 308 {
 309         rc32434_wdt_stop();
 310 }
 311
 312 static struct platform_driver rc32434_wdt_driver = {
 313         .probe          = rc32434_wdt_probe,
 314         .remove         = rc32434_wdt_remove,
 315         .shutdown       = rc32434_wdt_shutdown,
 316         .driver         = {
 317                         .name = "rc32434_wdt",
 318         }
 319 };
 320
 321 module_platform_driver(rc32434_wdt_driver);
 322
 323 MODULE_AUTHOR("Ondrej Zajicek <santiago@crfreenet.org>,"
 324                 "Florian Fainelli <florian@openwrt.org>");
 325 MODULE_DESCRIPTION("Driver for the IDT RC32434 SoC watchdog");
 326 MODULE_LICENSE("GPL");