drivers/watchdog/of_xilinx_wdt.c

   1 /*
   2  * Watchdog Device Driver for Xilinx axi/xps_timebase_wdt
   3  *
   4  * (C) Copyright 2011 (Alejandro Cabrera <aldaya@gmail.com>)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  13
  14 #include <linux/module.h>
  15 #include <linux/types.h>
  16 #include <linux/kernel.h>
  17 #include <linux/fs.h>
  18 #include <linux/miscdevice.h>
  19 #include <linux/init.h>
  20 #include <linux/ioport.h>
  21 #include <linux/watchdog.h>
  22 #include <linux/io.h>
  23 #include <linux/uaccess.h>
  24 #include <linux/of.h>
  25 #include <linux/of_device.h>
  26 #include <linux/of_address.h>
  27
  28 /* Register offsets for the Wdt device */
  29 #define XWT_TWCSR0_OFFSET   0x0 /* Control/Status Register0 */
  30 #define XWT_TWCSR1_OFFSET   0x4 /* Control/Status Register1 */
  31 #define XWT_TBR_OFFSET      0x8 /* Timebase Register Offset */
  32
  33 /* Control/Status Register Masks  */
  34 #define XWT_CSR0_WRS_MASK   0x00000008 /* Reset status */
  35 #define XWT_CSR0_WDS_MASK   0x00000004 /* Timer state  */
  36 #define XWT_CSR0_EWDT1_MASK 0x00000002 /* Enable bit 1 */
  37
  38 /* Control/Status Register 0/1 bits  */
  39 #define XWT_CSRX_EWDT2_MASK 0x00000001 /* Enable bit 2 */
  40
  41 /* SelfTest constants */
  42 #define XWT_MAX_SELFTEST_LOOP_COUNT 0x00010000
  43 #define XWT_TIMER_FAILED            0xFFFFFFFF
  44
  45 #define WATCHDOG_NAME     "Xilinx Watchdog"
  46 #define PFX WATCHDOG_NAME ": "
  47
  48 struct xwdt_device {
  49         struct resource  res;
  50         void __iomem *base;
  51         u32 nowayout;
  52         u32 wdt_interval;
  53         u32 boot_status;
  54 };
  55
  56 static struct xwdt_device xdev;
  57
  58 static  u32 timeout;
  59 static  u32 control_status_reg;
  60 static  u8  expect_close;
  61 static  u8  no_timeout;
  62 static unsigned long driver_open;
  63
  64 static  DEFINE_SPINLOCK(spinlock);
  65
  66 static void xwdt_start(void)
  67 {
  68         spin_lock(&spinlock);
  69
  70         /* Clean previous status and enable the watchdog timer */
  71         control_status_reg = ioread32(xdev.base + XWT_TWCSR0_OFFSET);
  72         control_status_reg |= (XWT_CSR0_WRS_MASK | XWT_CSR0_WDS_MASK);
  73
  74         iowrite32((control_status_reg | XWT_CSR0_EWDT1_MASK),
  75                                 xdev.base + XWT_TWCSR0_OFFSET);
  76
  77         iowrite32(XWT_CSRX_EWDT2_MASK, xdev.base + XWT_TWCSR1_OFFSET);
  78
  79         spin_unlock(&spinlock);
  80 }
  81
  82 static void xwdt_stop(void)
  83 {
  84         spin_lock(&spinlock);
  85
  86         control_status_reg = ioread32(xdev.base + XWT_TWCSR0_OFFSET);
  87
  88         iowrite32((control_status_reg & ~XWT_CSR0_EWDT1_MASK),
  89                                 xdev.base + XWT_TWCSR0_OFFSET);
  90
  91         iowrite32(0, xdev.base + XWT_TWCSR1_OFFSET);
  92
  93         spin_unlock(&spinlock);
  94         pr_info("Stopped!\n");
  95 }
  96
  97 static void xwdt_keepalive(void)
  98 {
  99         spin_lock(&spinlock);
 100
 101         control_status_reg = ioread32(xdev.base + XWT_TWCSR0_OFFSET);
 102         control_status_reg |= (XWT_CSR0_WRS_MASK | XWT_CSR0_WDS_MASK);
 103         iowrite32(control_status_reg, xdev.base + XWT_TWCSR0_OFFSET);
 104
 105         spin_unlock(&spinlock);
 106 }
 107
 108 static void xwdt_get_status(int *status)
 109 {
 110         int new_status;
 111
 112         spin_lock(&spinlock);
 113
 114         control_status_reg = ioread32(xdev.base + XWT_TWCSR0_OFFSET);
 115         new_status = ((control_status_reg &
 116                         (XWT_CSR0_WRS_MASK | XWT_CSR0_WDS_MASK)) != 0);
 117         spin_unlock(&spinlock);
 118
 119         *status = 0;
 120         if (new_status & 1)
 121                 *status |= WDIOF_CARDRESET;
 122 }
 123
 124 static u32 xwdt_selftest(void)
 125 {
 126         int i;
 127         u32 timer_value1;
 128         u32 timer_value2;
 129
 130         spin_lock(&spinlock);
 131
 132         timer_value1 = ioread32(xdev.base + XWT_TBR_OFFSET);
 133         timer_value2 = ioread32(xdev.base + XWT_TBR_OFFSET);
 134
 135         for (i = 0;
 136                 ((i <= XWT_MAX_SELFTEST_LOOP_COUNT) &&
 137                         (timer_value2 == timer_value1)); i++) {
 138                 timer_value2 = ioread32(xdev.base + XWT_TBR_OFFSET);
 139         }
 140
 141         spin_unlock(&spinlock);
 142
 143         if (timer_value2 != timer_value1)
 144                 return ~XWT_TIMER_FAILED;
 145         else
 146                 return XWT_TIMER_FAILED;
 147 }
 148
 149 static int xwdt_open(struct inode *inode, struct file *file)
 150 {
 151         /* Only one process can handle the wdt at a time */
 152         if (test_and_set_bit(0, &driver_open))
 153                 return -EBUSY;
 154
 155         /* Make sure that the module are always loaded...*/
 156         if (xdev.nowayout)
 157                 __module_get(THIS_MODULE);
 158
 159         xwdt_start();
 160         pr_info("Started...\n");
 161
 162         return nonseekable_open(inode, file);
 163 }
 164
 165 static int xwdt_release(struct inode *inode, struct file *file)
 166 {
 167         if (expect_close == 42) {
 168                 xwdt_stop();
 169         } else {
 170                 pr_crit("Unexpected close, not stopping watchdog!\n");
 171                 xwdt_keepalive();
 172         }
 173
 174         clear_bit(0, &driver_open);
 175         expect_close = 0;
 176         return 0;
 177 }
 178
 179 /*
 180  *      xwdt_write:
 181  *      @file: file handle to the watchdog
 182  *      @buf: buffer to write (unused as data does not matter here
 183  *      @count: count of bytes
 184  *      @ppos: pointer to the position to write. No seeks allowed
 185  *
 186  *      A write to a watchdog device is defined as a keepalive signal. Any
 187  *      write of data will do, as we don't define content meaning.
 188  */
 189 static ssize_t xwdt_write(struct file *file, const char __user *buf,
 190                                                 size_t len, loff_t *ppos)
 191 {
 192         if (len) {
 193                 if (!xdev.nowayout) {
 194                         size_t i;
 195
 196                         /* In case it was set long ago */
 197                         expect_close = 0;
 198
 199                         for (i = 0; i != len; i++) {
 200                                 char c;
 201
 202                                 if (get_user(c, buf + i))
 203                                         return -EFAULT;
 204                                 if (c == 'V')
 205                                         expect_close = 42;
 206                         }
 207                 }
 208                 xwdt_keepalive();
 209         }
 210         return len;
 211 }
 212
 213 static const struct watchdog_info ident = {
 214         .options =  WDIOF_MAGICCLOSE |
 215                     WDIOF_KEEPALIVEPING,
 216         .firmware_version =     1,
 217         .identity =     WATCHDOG_NAME,
 218 };
 219
 220 /*
 221  *      xwdt_ioctl:
 222  *      @file: file handle to the device
 223  *      @cmd: watchdog command
 224  *      @arg: argument pointer
 225  *
 226  *      The watchdog API defines a common set of functions for all watchdogs
 227  *      according to their available features.
 228  */
 229 static long xwdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 230 {
 231         int status;
 232
 233         union {
 234                 struct watchdog_info __user *ident;
 235                 int __user *i;
 236         } uarg;
 237
 238         uarg.i = (int __user *)arg;
 239
 240         switch (cmd) {
 241         case WDIOC_GETSUPPORT:
 242                 return copy_to_user(uarg.ident, &ident,
 243                                         sizeof(ident)) ? -EFAULT : 0;
 244
 245         case WDIOC_GETBOOTSTATUS:
 246                 return put_user(xdev.boot_status, uarg.i);
 247
 248         case WDIOC_GETSTATUS:
 249                 xwdt_get_status(&status);
 250                 return put_user(status, uarg.i);
 251
 252         case WDIOC_KEEPALIVE:
 253                 xwdt_keepalive();
 254                 return 0;
 255
 256         case WDIOC_GETTIMEOUT:
 257                 if (no_timeout)
 258                         return -ENOTTY;
 259                 else
 260                         return put_user(timeout, uarg.i);
 261
 262         default:
 263                 return -ENOTTY;
 264         }
 265 }
 266
 267 static const struct file_operations xwdt_fops = {
 268         .owner      = THIS_MODULE,
 269         .llseek     = no_llseek,
 270         .write      = xwdt_write,
 271         .open       = xwdt_open,
 272         .release    = xwdt_release,
 273         .unlocked_ioctl = xwdt_ioctl,
 274 };
 275
 276 static struct miscdevice xwdt_miscdev = {
 277         .minor      = WATCHDOG_MINOR,
 278         .name       = "watchdog",
 279         .fops       = &xwdt_fops,
 280 };
 281
 282 static int xwdt_probe(struct platform_device *pdev)
 283 {
 284         int rc;
 285         u32 *tmptr;
 286         u32 *pfreq;
 287
 288         no_timeout = 0;
 289
 290         pfreq = (u32 *)of_get_property(pdev->dev.of_node,
 291                                         "clock-frequency", NULL);
 292
 293         if (pfreq == NULL) {
 294                 pr_warn("The watchdog clock frequency cannot be obtained!\n");
 295                 no_timeout = 1;
 296         }
 297
 298         rc = of_address_to_resource(pdev->dev.of_node, 0, &xdev.res);
 299         if (rc) {
 300                 pr_warn("invalid address!\n");
 301                 return rc;
 302         }
 303
 304         tmptr = (u32 *)of_get_property(pdev->dev.of_node,
 305                                         "xlnx,wdt-interval", NULL);
 306         if (tmptr == NULL) {
 307                 pr_warn("Parameter \"xlnx,wdt-interval\" not found in device tree!\n");
 308                 no_timeout = 1;
 309         } else {
 310                 xdev.wdt_interval = *tmptr;
 311         }
 312
 313         tmptr = (u32 *)of_get_property(pdev->dev.of_node,
 314                                         "xlnx,wdt-enable-once", NULL);
 315         if (tmptr == NULL) {
 316                 pr_warn("Parameter \"xlnx,wdt-enable-once\" not found in device tree!\n");
 317                 xdev.nowayout = WATCHDOG_NOWAYOUT;
 318         }
 319
 320 /*
 321  *  Twice of the 2^wdt_interval / freq  because the first wdt overflow is
 322  *  ignored (interrupt), reset is only generated at second wdt overflow
 323  */
 324         if (!no_timeout)
 325                 timeout = 2 * ((1<<xdev.wdt_interval) / *pfreq);
 326
 327         if (!request_mem_region(xdev.res.start,
 328                         xdev.res.end - xdev.res.start + 1, WATCHDOG_NAME)) {
 329                 rc = -ENXIO;
 330                 pr_err("memory request failure!\n");
 331                 goto err_out;
 332         }
 333
 334         xdev.base = ioremap(xdev.res.start, xdev.res.end - xdev.res.start + 1);
 335         if (xdev.base == NULL) {
 336                 rc = -ENOMEM;
 337                 pr_err("ioremap failure!\n");
 338                 goto release_mem;
 339         }
 340
 341         rc = xwdt_selftest();
 342         if (rc == XWT_TIMER_FAILED) {
 343                 pr_err("SelfTest routine error!\n");
 344                 goto unmap_io;
 345         }
 346
 347         xwdt_get_status(&xdev.boot_status);
 348
 349         rc = misc_register(&xwdt_miscdev);
 350         if (rc) {
 351                 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
 352                        xwdt_miscdev.minor, rc);
 353                 goto unmap_io;
 354         }
 355
 356         if (no_timeout)
 357                 pr_info("driver loaded (timeout=? sec, nowayout=%d)\n",
 358                         xdev.nowayout);
 359         else
 360                 pr_info("driver loaded (timeout=%d sec, nowayout=%d)\n",
 361                         timeout, xdev.nowayout);
 362
 363         expect_close = 0;
 364         clear_bit(0, &driver_open);
 365
 366         return 0;
 367
 368 unmap_io:
 369         iounmap(xdev.base);
 370 release_mem:
 371         release_mem_region(xdev.res.start, resource_size(&xdev.res));
 372 err_out:
 373         return rc;
 374 }
 375
 376 static int xwdt_remove(struct platform_device *dev)
 377 {
 378         misc_deregister(&xwdt_miscdev);
 379         iounmap(xdev.base);
 380         release_mem_region(xdev.res.start, resource_size(&xdev.res));
 381
 382         return 0;
 383 }
 384
 385 /* Match table for of_platform binding */
 386 static struct of_device_id xwdt_of_match[] = {
 387         { .compatible = "xlnx,xps-timebase-wdt-1.00.a", },
 388         { .compatible = "xlnx,xps-timebase-wdt-1.01.a", },
 389         {},
 390 };
 391 MODULE_DEVICE_TABLE(of, xwdt_of_match);
 392
 393 static struct platform_driver xwdt_driver = {
 394         .probe       = xwdt_probe,
 395         .remove      = xwdt_remove,
 396         .driver = {
 397                 .owner = THIS_MODULE,
 398                 .name  = WATCHDOG_NAME,
 399                 .of_match_table = xwdt_of_match,
 400         },
 401 };
 402
 403 module_platform_driver(xwdt_driver);
 404
 405 MODULE_AUTHOR("Alejandro Cabrera <aldaya@gmail.com>");
 406 MODULE_DESCRIPTION("Xilinx Watchdog driver");
 407 MODULE_LICENSE("GPL v2");