drivers/watchdog/mv64x60_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * mv64x60_wdt.c - MV64X60 (Marvell Discovery) watchdog userspace interface
   4  *
   5  * Author: James Chapman <jchapman@katalix.com>
   6  *
   7  * Platform-specific setup code should configure the dog to generate
   8  * interrupt or reset as required.  This code only enables/disables
   9  * and services the watchdog.
  10  *
  11  * Derived from mpc8xx_wdt.c, with the following copyright.
  12  *
  13  * 2002 (c) Florian Schirmer <jolt@tuxbox.org>
  14  */
  15
  16 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  17
  18 #include <linux/fs.h>
  19 #include <linux/init.h>
  20 #include <linux/kernel.h>
  21 #include <linux/miscdevice.h>
  22 #include <linux/module.h>
  23 #include <linux/watchdog.h>
  24 #include <linux/platform_device.h>
  25 #include <linux/mv643xx.h>
  26 #include <linux/uaccess.h>
  27 #include <linux/io.h>
  28
  29 #define MV64x60_WDT_WDC_OFFSET  0
  30
  31 /*
  32  * The watchdog configuration register contains a pair of 2-bit fields,
  33  *   1.  a reload field, bits 27-26, which triggers a reload of
  34  *       the countdown register, and
  35  *   2.  an enable field, bits 25-24, which toggles between
  36  *       enabling and disabling the watchdog timer.
  37  * Bit 31 is a read-only field which indicates whether the
  38  * watchdog timer is currently enabled.
  39  *
  40  * The low 24 bits contain the timer reload value.
  41  */
  42 #define MV64x60_WDC_ENABLE_SHIFT        24
  43 #define MV64x60_WDC_SERVICE_SHIFT       26
  44 #define MV64x60_WDC_ENABLED_SHIFT       31
  45
  46 #define MV64x60_WDC_ENABLED_TRUE        1
  47 #define MV64x60_WDC_ENABLED_FALSE       0
  48
  49 /* Flags bits */
  50 #define MV64x60_WDOG_FLAG_OPENED        0
  51
  52 static unsigned long wdt_flags;
  53 static int wdt_status;
  54 static void __iomem *mv64x60_wdt_regs;
  55 static int mv64x60_wdt_timeout;
  56 static int mv64x60_wdt_count;
  57 static unsigned int bus_clk;
  58 static char expect_close;
  59 static DEFINE_SPINLOCK(mv64x60_wdt_spinlock);
  60
  61 static bool nowayout = WATCHDOG_NOWAYOUT;
  62 module_param(nowayout, bool, 0);
  63 MODULE_PARM_DESC(nowayout,
  64                 "Watchdog cannot be stopped once started (default="
  65                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  66
  67 static int mv64x60_wdt_toggle_wdc(int enabled_predicate, int field_shift)
  68 {
  69         u32 data;
  70         u32 enabled;
  71         int ret = 0;
  72
  73         spin_lock(&mv64x60_wdt_spinlock);
  74         data = readl(mv64x60_wdt_regs + MV64x60_WDT_WDC_OFFSET);
  75         enabled = (data >> MV64x60_WDC_ENABLED_SHIFT) & 1;
  76
  77         /* only toggle the requested field if enabled state matches predicate */
  78         if ((enabled ^ enabled_predicate) == 0) {
  79                 /* We write a 1, then a 2 -- to the appropriate field */
  80                 data = (1 << field_shift) | mv64x60_wdt_count;
  81                 writel(data, mv64x60_wdt_regs + MV64x60_WDT_WDC_OFFSET);
  82
  83                 data = (2 << field_shift) | mv64x60_wdt_count;
  84                 writel(data, mv64x60_wdt_regs + MV64x60_WDT_WDC_OFFSET);
  85                 ret = 1;
  86         }
  87         spin_unlock(&mv64x60_wdt_spinlock);
  88
  89         return ret;
  90 }
  91
  92 static void mv64x60_wdt_service(void)
  93 {
  94         mv64x60_wdt_toggle_wdc(MV64x60_WDC_ENABLED_TRUE,
  95                                MV64x60_WDC_SERVICE_SHIFT);
  96 }
  97
  98 static void mv64x60_wdt_handler_enable(void)
  99 {
 100         if (mv64x60_wdt_toggle_wdc(MV64x60_WDC_ENABLED_FALSE,
 101                                    MV64x60_WDC_ENABLE_SHIFT)) {
 102                 mv64x60_wdt_service();
 103                 pr_notice("watchdog activated\n");
 104         }
 105 }
 106
 107 static void mv64x60_wdt_handler_disable(void)
 108 {
 109         if (mv64x60_wdt_toggle_wdc(MV64x60_WDC_ENABLED_TRUE,
 110                                    MV64x60_WDC_ENABLE_SHIFT))
 111                 pr_notice("watchdog deactivated\n");
 112 }
 113
 114 static void mv64x60_wdt_set_timeout(unsigned int timeout)
 115 {
 116         /* maximum bus cycle count is 0xFFFFFFFF */
 117         if (timeout > 0xFFFFFFFF / bus_clk)
 118                 timeout = 0xFFFFFFFF / bus_clk;
 119
 120         mv64x60_wdt_count = timeout * bus_clk >> 8;
 121         mv64x60_wdt_timeout = timeout;
 122 }
 123
 124 static int mv64x60_wdt_open(struct inode *inode, struct file *file)
 125 {
 126         if (test_and_set_bit(MV64x60_WDOG_FLAG_OPENED, &wdt_flags))
 127                 return -EBUSY;
 128
 129         if (nowayout)
 130                 __module_get(THIS_MODULE);
 131
 132         mv64x60_wdt_handler_enable();
 133
 134         return stream_open(inode, file);
 135 }
 136
 137 static int mv64x60_wdt_release(struct inode *inode, struct file *file)
 138 {
 139         if (expect_close == 42)
 140                 mv64x60_wdt_handler_disable();
 141         else {
 142                 pr_crit("unexpected close, not stopping timer!\n");
 143                 mv64x60_wdt_service();
 144         }
 145         expect_close = 0;
 146
 147         clear_bit(MV64x60_WDOG_FLAG_OPENED, &wdt_flags);
 148
 149         return 0;
 150 }
 151
 152 static ssize_t mv64x60_wdt_write(struct file *file, const char __user *data,
 153                                  size_t len, loff_t *ppos)
 154 {
 155         if (len) {
 156                 if (!nowayout) {
 157                         size_t i;
 158
 159                         expect_close = 0;
 160
 161                         for (i = 0; i != len; i++) {
 162                                 char c;
 163                                 if (get_user(c, data + i))
 164                                         return -EFAULT;
 165                                 if (c == 'V')
 166                                         expect_close = 42;
 167                         }
 168                 }
 169                 mv64x60_wdt_service();
 170         }
 171
 172         return len;
 173 }
 174
 175 static long mv64x60_wdt_ioctl(struct file *file,
 176                                         unsigned int cmd, unsigned long arg)
 177 {
 178         int timeout;
 179         int options;
 180         void __user *argp = (void __user *)arg;
 181         static const struct watchdog_info info = {
 182                 .options =      WDIOF_SETTIMEOUT        |
 183                                 WDIOF_MAGICCLOSE        |
 184                                 WDIOF_KEEPALIVEPING,
 185                 .firmware_version = 0,
 186                 .identity = "MV64x60 watchdog",
 187         };
 188
 189         switch (cmd) {
 190         case WDIOC_GETSUPPORT:
 191                 if (copy_to_user(argp, &info, sizeof(info)))
 192                         return -EFAULT;
 193                 break;
 194
 195         case WDIOC_GETSTATUS:
 196         case WDIOC_GETBOOTSTATUS:
 197                 if (put_user(wdt_status, (int __user *)argp))
 198                         return -EFAULT;
 199                 wdt_status &= ~WDIOF_KEEPALIVEPING;
 200                 break;
 201
 202         case WDIOC_GETTEMP:
 203                 return -EOPNOTSUPP;
 204
 205         case WDIOC_SETOPTIONS:
 206                 if (get_user(options, (int __user *)argp))
 207                         return -EFAULT;
 208
 209                 if (options & WDIOS_DISABLECARD)
 210                         mv64x60_wdt_handler_disable();
 211
 212                 if (options & WDIOS_ENABLECARD)
 213                         mv64x60_wdt_handler_enable();
 214                 break;
 215
 216         case WDIOC_KEEPALIVE:
 217                 mv64x60_wdt_service();
 218                 wdt_status |= WDIOF_KEEPALIVEPING;
 219                 break;
 220
 221         case WDIOC_SETTIMEOUT:
 222                 if (get_user(timeout, (int __user *)argp))
 223                         return -EFAULT;
 224                 mv64x60_wdt_set_timeout(timeout);
 225                 fallthrough;
 226
 227         case WDIOC_GETTIMEOUT:
 228                 if (put_user(mv64x60_wdt_timeout, (int __user *)argp))
 229                         return -EFAULT;
 230                 break;
 231
 232         default:
 233                 return -ENOTTY;
 234         }
 235
 236         return 0;
 237 }
 238
 239 static const struct file_operations mv64x60_wdt_fops = {
 240         .owner = THIS_MODULE,
 241         .llseek = no_llseek,
 242         .write = mv64x60_wdt_write,
 243         .unlocked_ioctl = mv64x60_wdt_ioctl,
 244         .compat_ioctl = compat_ptr_ioctl,
 245         .open = mv64x60_wdt_open,
 246         .release = mv64x60_wdt_release,
 247 };
 248
 249 static struct miscdevice mv64x60_wdt_miscdev = {
 250         .minor = WATCHDOG_MINOR,
 251         .name = "watchdog",
 252         .fops = &mv64x60_wdt_fops,
 253 };
 254
 255 static int mv64x60_wdt_probe(struct platform_device *dev)
 256 {
 257         struct mv64x60_wdt_pdata *pdata = dev_get_platdata(&dev->dev);
 258         struct resource *r;
 259         int timeout = 10;
 260
 261         bus_clk = 133;                  /* in MHz */
 262         if (pdata) {
 263                 timeout = pdata->timeout;
 264                 bus_clk = pdata->bus_clk;
 265         }
 266
 267         /* Since bus_clk is truncated MHz, actual frequency could be
 268          * up to 1MHz higher.  Round up, since it's better to time out
 269          * too late than too soon.
 270          */
 271         bus_clk++;
 272         bus_clk *= 1000000;             /* convert to Hz */
 273
 274         r = platform_get_resource(dev, IORESOURCE_MEM, 0);
 275         if (!r)
 276                 return -ENODEV;
 277
 278         mv64x60_wdt_regs = devm_ioremap(&dev->dev, r->start, resource_size(r));
 279         if (mv64x60_wdt_regs == NULL)
 280                 return -ENOMEM;
 281
 282         mv64x60_wdt_set_timeout(timeout);
 283
 284         mv64x60_wdt_handler_disable();  /* in case timer was already running */
 285
 286         return misc_register(&mv64x60_wdt_miscdev);
 287 }
 288
 289 static int mv64x60_wdt_remove(struct platform_device *dev)
 290 {
 291         misc_deregister(&mv64x60_wdt_miscdev);
 292
 293         mv64x60_wdt_handler_disable();
 294
 295         return 0;
 296 }
 297
 298 static struct platform_driver mv64x60_wdt_driver = {
 299         .probe = mv64x60_wdt_probe,
 300         .remove = mv64x60_wdt_remove,
 301         .driver = {
 302                 .name = MV64x60_WDT_NAME,
 303         },
 304 };
 305
 306 static int __init mv64x60_wdt_init(void)
 307 {
 308         pr_info("MV64x60 watchdog driver\n");
 309
 310         return platform_driver_register(&mv64x60_wdt_driver);
 311 }
 312
 313 static void __exit mv64x60_wdt_exit(void)
 314 {
 315         platform_driver_unregister(&mv64x60_wdt_driver);
 316 }
 317
 318 module_init(mv64x60_wdt_init);
 319 module_exit(mv64x60_wdt_exit);
 320
 321 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
 322 MODULE_DESCRIPTION("MV64x60 watchdog driver");
 323 MODULE_LICENSE("GPL");
 324 MODULE_ALIAS("platform:" MV64x60_WDT_NAME);