linux/drivers/watchdog/ar7_wdt.c
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   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
  46MODULE_AUTHOR("Nicolas Thill <nico@openwrt.org>");
  47MODULE_DESCRIPTION(LONGNAME);
  48MODULE_LICENSE("GPL");
  49MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
  50
  51static int margin = 60;
  52module_param(margin, int, 0);
  53MODULE_PARM_DESC(margin, "Watchdog margin in seconds");
  54
  55static bool nowayout = WATCHDOG_NOWAYOUT;
  56module_param(nowayout, bool, 0);
  57MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
  58
  59#define READ_REG(x) readl((void __iomem *)&(x))
  60#define WRITE_REG(x, v) writel((v), (void __iomem *)&(x))
  61
  62struct ar7_wdt {
  63        u32 kick_lock;
  64        u32 kick;
  65        u32 change_lock;
  66        u32 change;
  67        u32 disable_lock;
  68        u32 disable;
  69        u32 prescale_lock;
  70        u32 prescale;
  71};
  72
  73static unsigned long wdt_is_open;
  74static unsigned expect_close;
  75static DEFINE_SPINLOCK(wdt_lock);
  76
  77/* XXX currently fixed, allows max margin ~68.72 secs */
  78#define prescale_value 0xffff
  79
  80/* Resource of the WDT registers */
  81static struct resource *ar7_regs_wdt;
  82/* Pointer to the remapped WDT IO space */
  83static struct ar7_wdt *ar7_wdt;
  84
  85static struct clk *vbus_clk;
  86
  87static void ar7_wdt_kick(u32 value)
  88{
  89        WRITE_REG(ar7_wdt->kick_lock, 0x5555);
  90        if ((READ_REG(ar7_wdt->kick_lock) & 3) == 1) {
  91                WRITE_REG(ar7_wdt->kick_lock, 0xaaaa);
  92                if ((READ_REG(ar7_wdt->kick_lock) & 3) == 3) {
  93                        WRITE_REG(ar7_wdt->kick, value);
  94                        return;
  95                }
  96        }
  97        pr_err("failed to unlock WDT kick reg\n");
  98}
  99
 100static void ar7_wdt_prescale(u32 value)
 101{
 102        WRITE_REG(ar7_wdt->prescale_lock, 0x5a5a);
 103        if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 1) {
 104                WRITE_REG(ar7_wdt->prescale_lock, 0xa5a5);
 105                if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 3) {
 106                        WRITE_REG(ar7_wdt->prescale, value);
 107                        return;
 108                }
 109        }
 110        pr_err("failed to unlock WDT prescale reg\n");
 111}
 112
 113static void ar7_wdt_change(u32 value)
 114{
 115        WRITE_REG(ar7_wdt->change_lock, 0x6666);
 116        if ((READ_REG(ar7_wdt->change_lock) & 3) == 1) {
 117                WRITE_REG(ar7_wdt->change_lock, 0xbbbb);
 118                if ((READ_REG(ar7_wdt->change_lock) & 3) == 3) {
 119                        WRITE_REG(ar7_wdt->change, value);
 120                        return;
 121                }
 122        }
 123        pr_err("failed to unlock WDT change reg\n");
 124}
 125
 126static void ar7_wdt_disable(u32 value)
 127{
 128        WRITE_REG(ar7_wdt->disable_lock, 0x7777);
 129        if ((READ_REG(ar7_wdt->disable_lock) & 3) == 1) {
 130                WRITE_REG(ar7_wdt->disable_lock, 0xcccc);
 131                if ((READ_REG(ar7_wdt->disable_lock) & 3) == 2) {
 132                        WRITE_REG(ar7_wdt->disable_lock, 0xdddd);
 133                        if ((READ_REG(ar7_wdt->disable_lock) & 3) == 3) {
 134                                WRITE_REG(ar7_wdt->disable, value);
 135                                return;
 136                        }
 137                }
 138        }
 139        pr_err("failed to unlock WDT disable reg\n");
 140}
 141
 142static void ar7_wdt_update_margin(int new_margin)
 143{
 144        u32 change;
 145        u32 vbus_rate;
 146
 147        vbus_rate = clk_get_rate(vbus_clk);
 148        change = new_margin * (vbus_rate / prescale_value);
 149        if (change < 1)
 150                change = 1;
 151        if (change > 0xffff)
 152                change = 0xffff;
 153        ar7_wdt_change(change);
 154        margin = change * prescale_value / vbus_rate;
 155        pr_info("timer margin %d seconds (prescale %d, change %d, freq %d)\n",
 156                margin, prescale_value, change, vbus_rate);
 157}
 158
 159static void ar7_wdt_enable_wdt(void)
 160{
 161        pr_debug("enabling watchdog timer\n");
 162        ar7_wdt_disable(1);
 163        ar7_wdt_kick(1);
 164}
 165
 166static void ar7_wdt_disable_wdt(void)
 167{
 168        pr_debug("disabling watchdog timer\n");
 169        ar7_wdt_disable(0);
 170}
 171
 172static int ar7_wdt_open(struct inode *inode, struct file *file)
 173{
 174        /* only allow one at a time */
 175        if (test_and_set_bit(0, &wdt_is_open))
 176                return -EBUSY;
 177        ar7_wdt_enable_wdt();
 178        expect_close = 0;
 179
 180        return nonseekable_open(inode, file);
 181}
 182
 183static int ar7_wdt_release(struct inode *inode, struct file *file)
 184{
 185        if (!expect_close)
 186                pr_warn("watchdog device closed unexpectedly, will not disable the watchdog timer\n");
 187        else if (!nowayout)
 188                ar7_wdt_disable_wdt();
 189        clear_bit(0, &wdt_is_open);
 190        return 0;
 191}
 192
 193static ssize_t ar7_wdt_write(struct file *file, const char *data,
 194                             size_t len, loff_t *ppos)
 195{
 196        /* check for a magic close character */
 197        if (len) {
 198                size_t i;
 199
 200                spin_lock(&wdt_lock);
 201                ar7_wdt_kick(1);
 202                spin_unlock(&wdt_lock);
 203
 204                expect_close = 0;
 205                for (i = 0; i < len; ++i) {
 206                        char c;
 207                        if (get_user(c, data + i))
 208                                return -EFAULT;
 209                        if (c == 'V')
 210                                expect_close = 1;
 211                }
 212
 213        }
 214        return len;
 215}
 216
 217static long ar7_wdt_ioctl(struct file *file,
 218                                        unsigned int cmd, unsigned long arg)
 219{
 220        static const struct watchdog_info ident = {
 221                .identity = LONGNAME,
 222                .firmware_version = 1,
 223                .options = (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
 224                                                WDIOF_MAGICCLOSE),
 225        };
 226        int new_margin;
 227
 228        switch (cmd) {
 229        case WDIOC_GETSUPPORT:
 230                if (copy_to_user((struct watchdog_info *)arg, &ident,
 231                                sizeof(ident)))
 232                        return -EFAULT;
 233                return 0;
 234        case WDIOC_GETSTATUS:
 235        case WDIOC_GETBOOTSTATUS:
 236                if (put_user(0, (int *)arg))
 237                        return -EFAULT;
 238                return 0;
 239        case WDIOC_KEEPALIVE:
 240                ar7_wdt_kick(1);
 241                return 0;
 242        case WDIOC_SETTIMEOUT:
 243                if (get_user(new_margin, (int *)arg))
 244                        return -EFAULT;
 245                if (new_margin < 1)
 246                        return -EINVAL;
 247
 248                spin_lock(&wdt_lock);
 249                ar7_wdt_update_margin(new_margin);
 250                ar7_wdt_kick(1);
 251                spin_unlock(&wdt_lock);
 252
 253        case WDIOC_GETTIMEOUT:
 254                if (put_user(margin, (int *)arg))
 255                        return -EFAULT;
 256                return 0;
 257        default:
 258                return -ENOTTY;
 259        }
 260}
 261
 262static const struct file_operations ar7_wdt_fops = {
 263        .owner          = THIS_MODULE,
 264        .write          = ar7_wdt_write,
 265        .unlocked_ioctl = ar7_wdt_ioctl,
 266        .open           = ar7_wdt_open,
 267        .release        = ar7_wdt_release,
 268        .llseek         = no_llseek,
 269};
 270
 271static struct miscdevice ar7_wdt_miscdev = {
 272        .minor          = WATCHDOG_MINOR,
 273        .name           = "watchdog",
 274        .fops           = &ar7_wdt_fops,
 275};
 276
 277static int ar7_wdt_probe(struct platform_device *pdev)
 278{
 279        int rc;
 280
 281        ar7_regs_wdt =
 282                platform_get_resource_byname(pdev, IORESOURCE_MEM, "regs");
 283        if (!ar7_regs_wdt) {
 284                pr_err("could not get registers resource\n");
 285                return -ENODEV;
 286        }
 287
 288        ar7_wdt = devm_ioremap_resource(&pdev->dev, ar7_regs_wdt);
 289        if (IS_ERR(ar7_wdt))
 290                return PTR_ERR(ar7_wdt);
 291
 292        vbus_clk = clk_get(NULL, "vbus");
 293        if (IS_ERR(vbus_clk)) {
 294                pr_err("could not get vbus clock\n");
 295                return PTR_ERR(vbus_clk);
 296        }
 297
 298        ar7_wdt_disable_wdt();
 299        ar7_wdt_prescale(prescale_value);
 300        ar7_wdt_update_margin(margin);
 301
 302        rc = misc_register(&ar7_wdt_miscdev);
 303        if (rc) {
 304                pr_err("unable to register misc device\n");
 305                goto out;
 306        }
 307        return 0;
 308
 309out:
 310        clk_put(vbus_clk);
 311        vbus_clk = NULL;
 312        return rc;
 313}
 314
 315static int ar7_wdt_remove(struct platform_device *pdev)
 316{
 317        misc_deregister(&ar7_wdt_miscdev);
 318        clk_put(vbus_clk);
 319        vbus_clk = NULL;
 320        return 0;
 321}
 322
 323static void ar7_wdt_shutdown(struct platform_device *pdev)
 324{
 325        if (!nowayout)
 326                ar7_wdt_disable_wdt();
 327}
 328
 329static struct platform_driver ar7_wdt_driver = {
 330        .probe = ar7_wdt_probe,
 331        .remove = ar7_wdt_remove,
 332        .shutdown = ar7_wdt_shutdown,
 333        .driver = {
 334                .owner = THIS_MODULE,
 335                .name = "ar7_wdt",
 336        },
 337};
 338
 339module_platform_driver(ar7_wdt_driver);
 340
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