drivers/watchdog/ar7_wdt.c

   1 /*
   2  * drivers/watchdog/ar7_wdt.c
   3  *
   4  * Copyright (C) 2007 Nicolas Thill <nico@openwrt.org>
   5  * Copyright (c) 2005 Enrik Berkhan <Enrik.Berkhan@akk.org>
   6  *
   7  * Some code taken from:
   8  * National Semiconductor SCx200 Watchdog support
   9  * Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com>
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License as published by
  13  * the Free Software Foundation; either version 2 of the License, or
  14  * (at your option) any later version.
  15  *
  16  * This program is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19  * GNU General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU General Public License
  22  * along with this program; if not, write to the Free Software
  23  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  24  */
  25
  26 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  27
  28 #include <linux/module.h>
  29 #include <linux/moduleparam.h>
  30 #include <linux/errno.h>
  31 #include <linux/init.h>
  32 #include <linux/miscdevice.h>
  33 #include <linux/platform_device.h>
  34 #include <linux/watchdog.h>
  35 #include <linux/fs.h>
  36 #include <linux/ioport.h>
  37 #include <linux/io.h>
  38 #include <linux/uaccess.h>
  39 #include <linux/clk.h>
  40
  41 #include <asm/addrspace.h>
  42 #include <asm/mach-ar7/ar7.h>
  43
  44 #define LONGNAME "TI AR7 Watchdog Timer"
  45
  46 MODULE_AUTHOR("Nicolas Thill <nico@openwrt.org>");
  47 MODULE_DESCRIPTION(LONGNAME);
  48 MODULE_LICENSE("GPL");
  49
  50 static int margin = 60;
  51 module_param(margin, int, 0);
  52 MODULE_PARM_DESC(margin, "Watchdog margin in seconds");
  53
  54 static bool nowayout = WATCHDOG_NOWAYOUT;
  55 module_param(nowayout, bool, 0);
  56 MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
  57
  58 #define READ_REG(x) readl((void __iomem *)&(x))
  59 #define WRITE_REG(x, v) writel((v), (void __iomem *)&(x))
  60
  61 struct ar7_wdt {
  62         u32 kick_lock;
  63         u32 kick;
  64         u32 change_lock;
  65         u32 change;
  66         u32 disable_lock;
  67         u32 disable;
  68         u32 prescale_lock;
  69         u32 prescale;
  70 };
  71
  72 static unsigned long wdt_is_open;
  73 static unsigned expect_close;
  74 static DEFINE_SPINLOCK(wdt_lock);
  75
  76 /* XXX currently fixed, allows max margin ~68.72 secs */
  77 #define prescale_value 0xffff
  78
  79 /* Resource of the WDT registers */
  80 static struct resource *ar7_regs_wdt;
  81 /* Pointer to the remapped WDT IO space */
  82 static struct ar7_wdt *ar7_wdt;
  83
  84 static struct clk *vbus_clk;
  85
  86 static void ar7_wdt_kick(u32 value)
  87 {
  88         WRITE_REG(ar7_wdt->kick_lock, 0x5555);
  89         if ((READ_REG(ar7_wdt->kick_lock) & 3) == 1) {
  90                 WRITE_REG(ar7_wdt->kick_lock, 0xaaaa);
  91                 if ((READ_REG(ar7_wdt->kick_lock) & 3) == 3) {
  92                         WRITE_REG(ar7_wdt->kick, value);
  93                         return;
  94                 }
  95         }
  96         pr_err("failed to unlock WDT kick reg\n");
  97 }
  98
  99 static void ar7_wdt_prescale(u32 value)
 100 {
 101         WRITE_REG(ar7_wdt->prescale_lock, 0x5a5a);
 102         if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 1) {
 103                 WRITE_REG(ar7_wdt->prescale_lock, 0xa5a5);
 104                 if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 3) {
 105                         WRITE_REG(ar7_wdt->prescale, value);
 106                         return;
 107                 }
 108         }
 109         pr_err("failed to unlock WDT prescale reg\n");
 110 }
 111
 112 static void ar7_wdt_change(u32 value)
 113 {
 114         WRITE_REG(ar7_wdt->change_lock, 0x6666);
 115         if ((READ_REG(ar7_wdt->change_lock) & 3) == 1) {
 116                 WRITE_REG(ar7_wdt->change_lock, 0xbbbb);
 117                 if ((READ_REG(ar7_wdt->change_lock) & 3) == 3) {
 118                         WRITE_REG(ar7_wdt->change, value);
 119                         return;
 120                 }
 121         }
 122         pr_err("failed to unlock WDT change reg\n");
 123 }
 124
 125 static void ar7_wdt_disable(u32 value)
 126 {
 127         WRITE_REG(ar7_wdt->disable_lock, 0x7777);
 128         if ((READ_REG(ar7_wdt->disable_lock) & 3) == 1) {
 129                 WRITE_REG(ar7_wdt->disable_lock, 0xcccc);
 130                 if ((READ_REG(ar7_wdt->disable_lock) & 3) == 2) {
 131                         WRITE_REG(ar7_wdt->disable_lock, 0xdddd);
 132                         if ((READ_REG(ar7_wdt->disable_lock) & 3) == 3) {
 133                                 WRITE_REG(ar7_wdt->disable, value);
 134                                 return;
 135                         }
 136                 }
 137         }
 138         pr_err("failed to unlock WDT disable reg\n");
 139 }
 140
 141 static void ar7_wdt_update_margin(int new_margin)
 142 {
 143         u32 change;
 144         u32 vbus_rate;
 145
 146         vbus_rate = clk_get_rate(vbus_clk);
 147         change = new_margin * (vbus_rate / prescale_value);
 148         if (change < 1)
 149                 change = 1;
 150         if (change > 0xffff)
 151                 change = 0xffff;
 152         ar7_wdt_change(change);
 153         margin = change * prescale_value / vbus_rate;
 154         pr_info("timer margin %d seconds (prescale %d, change %d, freq %d)\n",
 155                 margin, prescale_value, change, vbus_rate);
 156 }
 157
 158 static void ar7_wdt_enable_wdt(void)
 159 {
 160         pr_debug("enabling watchdog timer\n");
 161         ar7_wdt_disable(1);
 162         ar7_wdt_kick(1);
 163 }
 164
 165 static void ar7_wdt_disable_wdt(void)
 166 {
 167         pr_debug("disabling watchdog timer\n");
 168         ar7_wdt_disable(0);
 169 }
 170
 171 static int ar7_wdt_open(struct inode *inode, struct file *file)
 172 {
 173         /* only allow one at a time */
 174         if (test_and_set_bit(0, &wdt_is_open))
 175                 return -EBUSY;
 176         ar7_wdt_enable_wdt();
 177         expect_close = 0;
 178
 179         return nonseekable_open(inode, file);
 180 }
 181
 182 static int ar7_wdt_release(struct inode *inode, struct file *file)
 183 {
 184         if (!expect_close)
 185                 pr_warn("watchdog device closed unexpectedly, will not disable the watchdog timer\n");
 186         else if (!nowayout)
 187                 ar7_wdt_disable_wdt();
 188         clear_bit(0, &wdt_is_open);
 189         return 0;
 190 }
 191
 192 static ssize_t ar7_wdt_write(struct file *file, const char *data,
 193                              size_t len, loff_t *ppos)
 194 {
 195         /* check for a magic close character */
 196         if (len) {
 197                 size_t i;
 198
 199                 spin_lock(&wdt_lock);
 200                 ar7_wdt_kick(1);
 201                 spin_unlock(&wdt_lock);
 202
 203                 expect_close = 0;
 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                                 expect_close = 1;
 210                 }
 211
 212         }
 213         return len;
 214 }
 215
 216 static long ar7_wdt_ioctl(struct file *file,
 217                                         unsigned int cmd, unsigned long arg)
 218 {
 219         static const struct watchdog_info ident = {
 220                 .identity = LONGNAME,
 221                 .firmware_version = 1,
 222                 .options = (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
 223                                                 WDIOF_MAGICCLOSE),
 224         };
 225         int new_margin;
 226
 227         switch (cmd) {
 228         case WDIOC_GETSUPPORT:
 229                 if (copy_to_user((struct watchdog_info *)arg, &ident,
 230                                 sizeof(ident)))
 231                         return -EFAULT;
 232                 return 0;
 233         case WDIOC_GETSTATUS:
 234         case WDIOC_GETBOOTSTATUS:
 235                 if (put_user(0, (int *)arg))
 236                         return -EFAULT;
 237                 return 0;
 238         case WDIOC_KEEPALIVE:
 239                 ar7_wdt_kick(1);
 240                 return 0;
 241         case WDIOC_SETTIMEOUT:
 242                 if (get_user(new_margin, (int *)arg))
 243                         return -EFAULT;
 244                 if (new_margin < 1)
 245                         return -EINVAL;
 246
 247                 spin_lock(&wdt_lock);
 248                 ar7_wdt_update_margin(new_margin);
 249                 ar7_wdt_kick(1);
 250                 spin_unlock(&wdt_lock);
 251
 252         case WDIOC_GETTIMEOUT:
 253                 if (put_user(margin, (int *)arg))
 254                         return -EFAULT;
 255                 return 0;
 256         default:
 257                 return -ENOTTY;
 258         }
 259 }
 260
 261 static const struct file_operations ar7_wdt_fops = {
 262         .owner          = THIS_MODULE,
 263         .write          = ar7_wdt_write,
 264         .unlocked_ioctl = ar7_wdt_ioctl,
 265         .open           = ar7_wdt_open,
 266         .release        = ar7_wdt_release,
 267         .llseek         = no_llseek,
 268 };
 269
 270 static struct miscdevice ar7_wdt_miscdev = {
 271         .minor          = WATCHDOG_MINOR,
 272         .name           = "watchdog",
 273         .fops           = &ar7_wdt_fops,
 274 };
 275
 276 static int ar7_wdt_probe(struct platform_device *pdev)
 277 {
 278         int rc;
 279
 280         ar7_regs_wdt =
 281                 platform_get_resource_byname(pdev, IORESOURCE_MEM, "regs");
 282         ar7_wdt = devm_ioremap_resource(&pdev->dev, ar7_regs_wdt);
 283         if (IS_ERR(ar7_wdt))
 284                 return PTR_ERR(ar7_wdt);
 285
 286         vbus_clk = clk_get(NULL, "vbus");
 287         if (IS_ERR(vbus_clk)) {
 288                 pr_err("could not get vbus clock\n");
 289                 return PTR_ERR(vbus_clk);
 290         }
 291
 292         ar7_wdt_disable_wdt();
 293         ar7_wdt_prescale(prescale_value);
 294         ar7_wdt_update_margin(margin);
 295
 296         rc = misc_register(&ar7_wdt_miscdev);
 297         if (rc) {
 298                 pr_err("unable to register misc device\n");
 299                 goto out;
 300         }
 301         return 0;
 302
 303 out:
 304         clk_put(vbus_clk);
 305         vbus_clk = NULL;
 306         return rc;
 307 }
 308
 309 static int ar7_wdt_remove(struct platform_device *pdev)
 310 {
 311         misc_deregister(&ar7_wdt_miscdev);
 312         clk_put(vbus_clk);
 313         vbus_clk = NULL;
 314         return 0;
 315 }
 316
 317 static void ar7_wdt_shutdown(struct platform_device *pdev)
 318 {
 319         if (!nowayout)
 320                 ar7_wdt_disable_wdt();
 321 }
 322
 323 static struct platform_driver ar7_wdt_driver = {
 324         .probe = ar7_wdt_probe,
 325         .remove = ar7_wdt_remove,
 326         .shutdown = ar7_wdt_shutdown,
 327         .driver = {
 328                 .owner = THIS_MODULE,
 329                 .name = "ar7_wdt",
 330         },
 331 };
 332
 333 module_platform_driver(ar7_wdt_driver);