linux/drivers/watchdog/stmp3xxx_wdt.c
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   1/*
   2 * Watchdog driver for Freescale STMP37XX/STMP378X
   3 *
   4 * Author: Vitaly Wool <vital@embeddedalley.com>
   5 *
   6 * Copyright 2008 Freescale Semiconductor, Inc. All Rights Reserved.
   7 * Copyright 2008 Embedded Alley Solutions, Inc All Rights Reserved.
   8 */
   9#include <linux/init.h>
  10#include <linux/kernel.h>
  11#include <linux/fs.h>
  12#include <linux/miscdevice.h>
  13#include <linux/watchdog.h>
  14#include <linux/platform_device.h>
  15#include <linux/spinlock.h>
  16#include <linux/uaccess.h>
  17
  18#include <mach/platform.h>
  19#include <mach/regs-rtc.h>
  20
  21#define DEFAULT_HEARTBEAT       19
  22#define MAX_HEARTBEAT           (0x10000000 >> 6)
  23
  24/* missing bitmask in headers */
  25#define BV_RTC_PERSISTENT1_GENERAL__RTC_FORCE_UPDATER     0x80000000
  26
  27#define WDT_IN_USE              0
  28#define WDT_OK_TO_CLOSE         1
  29
  30#define WDOG_COUNTER_RATE       1000 /* 1 kHz clock */
  31
  32static DEFINE_SPINLOCK(stmp3xxx_wdt_io_lock);
  33static unsigned long wdt_status;
  34static const int nowayout = WATCHDOG_NOWAYOUT;
  35static int heartbeat = DEFAULT_HEARTBEAT;
  36static unsigned long boot_status;
  37
  38static void wdt_enable(u32 value)
  39{
  40        spin_lock(&stmp3xxx_wdt_io_lock);
  41        __raw_writel(value, REGS_RTC_BASE + HW_RTC_WATCHDOG);
  42        stmp3xxx_setl(BM_RTC_CTRL_WATCHDOGEN, REGS_RTC_BASE + HW_RTC_CTRL);
  43        stmp3xxx_setl(BV_RTC_PERSISTENT1_GENERAL__RTC_FORCE_UPDATER,
  44                        REGS_RTC_BASE + HW_RTC_PERSISTENT1);
  45        spin_unlock(&stmp3xxx_wdt_io_lock);
  46}
  47
  48static void wdt_disable(void)
  49{
  50        spin_lock(&stmp3xxx_wdt_io_lock);
  51        stmp3xxx_clearl(BV_RTC_PERSISTENT1_GENERAL__RTC_FORCE_UPDATER,
  52                        REGS_RTC_BASE + HW_RTC_PERSISTENT1);
  53        stmp3xxx_clearl(BM_RTC_CTRL_WATCHDOGEN, REGS_RTC_BASE + HW_RTC_CTRL);
  54        spin_unlock(&stmp3xxx_wdt_io_lock);
  55}
  56
  57static void wdt_ping(void)
  58{
  59        wdt_enable(heartbeat * WDOG_COUNTER_RATE);
  60}
  61
  62static int stmp3xxx_wdt_open(struct inode *inode, struct file *file)
  63{
  64        if (test_and_set_bit(WDT_IN_USE, &wdt_status))
  65                return -EBUSY;
  66
  67        clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  68        wdt_ping();
  69
  70        return nonseekable_open(inode, file);
  71}
  72
  73static ssize_t stmp3xxx_wdt_write(struct file *file, const char __user *data,
  74        size_t len, loff_t *ppos)
  75{
  76        if (len) {
  77                if (!nowayout) {
  78                        size_t i;
  79
  80                        clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  81
  82                        for (i = 0; i != len; i++) {
  83                                char c;
  84
  85                                if (get_user(c, data + i))
  86                                        return -EFAULT;
  87                                if (c == 'V')
  88                                        set_bit(WDT_OK_TO_CLOSE, &wdt_status);
  89                        }
  90                }
  91                wdt_ping();
  92        }
  93
  94        return len;
  95}
  96
  97static const struct watchdog_info ident = {
  98        .options        = WDIOF_CARDRESET |
  99                          WDIOF_MAGICCLOSE |
 100                          WDIOF_SETTIMEOUT |
 101                          WDIOF_KEEPALIVEPING,
 102        .identity       = "STMP3XXX Watchdog",
 103};
 104
 105static long stmp3xxx_wdt_ioctl(struct file *file, unsigned int cmd,
 106        unsigned long arg)
 107{
 108        void __user *argp = (void __user *)arg;
 109        int __user *p = argp;
 110        int new_heartbeat, opts;
 111        int ret = -ENOTTY;
 112
 113        switch (cmd) {
 114        case WDIOC_GETSUPPORT:
 115                ret = copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
 116                break;
 117
 118        case WDIOC_GETSTATUS:
 119                ret = put_user(0, p);
 120                break;
 121
 122        case WDIOC_GETBOOTSTATUS:
 123                ret = put_user(boot_status, p);
 124                break;
 125
 126        case WDIOC_SETOPTIONS:
 127                if (get_user(opts, p)) {
 128                        ret = -EFAULT;
 129                        break;
 130                }
 131                if (opts & WDIOS_DISABLECARD)
 132                        wdt_disable();
 133                else if (opts & WDIOS_ENABLECARD)
 134                        wdt_ping();
 135                else {
 136                        pr_debug("%s: unknown option 0x%x\n", __func__, opts);
 137                        ret = -EINVAL;
 138                        break;
 139                }
 140                ret = 0;
 141                break;
 142
 143        case WDIOC_KEEPALIVE:
 144                wdt_ping();
 145                ret = 0;
 146                break;
 147
 148        case WDIOC_SETTIMEOUT:
 149                if (get_user(new_heartbeat, p)) {
 150                        ret = -EFAULT;
 151                        break;
 152                }
 153                if (new_heartbeat <= 0 || new_heartbeat > MAX_HEARTBEAT) {
 154                        ret = -EINVAL;
 155                        break;
 156                }
 157
 158                heartbeat = new_heartbeat;
 159                wdt_ping();
 160                /* Fall through */
 161
 162        case WDIOC_GETTIMEOUT:
 163                ret = put_user(heartbeat, p);
 164                break;
 165        }
 166        return ret;
 167}
 168
 169static int stmp3xxx_wdt_release(struct inode *inode, struct file *file)
 170{
 171        int ret = 0;
 172
 173        if (!nowayout) {
 174                if (!test_bit(WDT_OK_TO_CLOSE, &wdt_status)) {
 175                        wdt_ping();
 176                        pr_debug("%s: Device closed unexpectdly\n", __func__);
 177                        ret = -EINVAL;
 178                } else {
 179                        wdt_disable();
 180                        clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 181                }
 182        }
 183        clear_bit(WDT_IN_USE, &wdt_status);
 184
 185        return ret;
 186}
 187
 188static const struct file_operations stmp3xxx_wdt_fops = {
 189        .owner = THIS_MODULE,
 190        .llseek = no_llseek,
 191        .write = stmp3xxx_wdt_write,
 192        .unlocked_ioctl = stmp3xxx_wdt_ioctl,
 193        .open = stmp3xxx_wdt_open,
 194        .release = stmp3xxx_wdt_release,
 195};
 196
 197static struct miscdevice stmp3xxx_wdt_miscdev = {
 198        .minor = WATCHDOG_MINOR,
 199        .name = "watchdog",
 200        .fops = &stmp3xxx_wdt_fops,
 201};
 202
 203static int __devinit stmp3xxx_wdt_probe(struct platform_device *pdev)
 204{
 205        int ret = 0;
 206
 207        if (heartbeat < 1 || heartbeat > MAX_HEARTBEAT)
 208                heartbeat = DEFAULT_HEARTBEAT;
 209
 210        boot_status = __raw_readl(REGS_RTC_BASE + HW_RTC_PERSISTENT1) &
 211                        BV_RTC_PERSISTENT1_GENERAL__RTC_FORCE_UPDATER;
 212        boot_status = !!boot_status;
 213        stmp3xxx_clearl(BV_RTC_PERSISTENT1_GENERAL__RTC_FORCE_UPDATER,
 214                        REGS_RTC_BASE + HW_RTC_PERSISTENT1);
 215        wdt_disable();          /* disable for now */
 216
 217        ret = misc_register(&stmp3xxx_wdt_miscdev);
 218        if (ret < 0) {
 219                dev_err(&pdev->dev, "cannot register misc device\n");
 220                return ret;
 221        }
 222
 223        printk(KERN_INFO "stmp3xxx watchdog: initialized, heartbeat %d sec\n",
 224                heartbeat);
 225
 226        return ret;
 227}
 228
 229static int __devexit stmp3xxx_wdt_remove(struct platform_device *pdev)
 230{
 231        misc_deregister(&stmp3xxx_wdt_miscdev);
 232        return 0;
 233}
 234
 235#ifdef CONFIG_PM
 236static int wdt_suspended;
 237static u32 wdt_saved_time;
 238
 239static int stmp3xxx_wdt_suspend(struct platform_device *pdev,
 240                                pm_message_t state)
 241{
 242        if (__raw_readl(REGS_RTC_BASE + HW_RTC_CTRL) &
 243                BM_RTC_CTRL_WATCHDOGEN) {
 244                wdt_suspended = 1;
 245                wdt_saved_time = __raw_readl(REGS_RTC_BASE + HW_RTC_WATCHDOG);
 246                wdt_disable();
 247        }
 248        return 0;
 249}
 250
 251static int stmp3xxx_wdt_resume(struct platform_device *pdev)
 252{
 253        if (wdt_suspended) {
 254                wdt_enable(wdt_saved_time);
 255                wdt_suspended = 0;
 256        }
 257        return 0;
 258}
 259#else
 260#define stmp3xxx_wdt_suspend    NULL
 261#define stmp3xxx_wdt_resume     NULL
 262#endif
 263
 264static struct platform_driver platform_wdt_driver = {
 265        .driver = {
 266                .name = "stmp3xxx_wdt",
 267        },
 268        .probe = stmp3xxx_wdt_probe,
 269        .remove = __devexit_p(stmp3xxx_wdt_remove),
 270        .suspend = stmp3xxx_wdt_suspend,
 271        .resume = stmp3xxx_wdt_resume,
 272};
 273
 274static int __init stmp3xxx_wdt_init(void)
 275{
 276        return platform_driver_register(&platform_wdt_driver);
 277}
 278
 279static void __exit stmp3xxx_wdt_exit(void)
 280{
 281        return platform_driver_unregister(&platform_wdt_driver);
 282}
 283
 284module_init(stmp3xxx_wdt_init);
 285module_exit(stmp3xxx_wdt_exit);
 286
 287MODULE_DESCRIPTION("STMP3XXX Watchdog Driver");
 288MODULE_LICENSE("GPL");
 289
 290module_param(heartbeat, int, 0);
 291MODULE_PARM_DESC(heartbeat,
 292                 "Watchdog heartbeat period in seconds from 1 to "
 293                 __MODULE_STRING(MAX_HEARTBEAT) ", default "
 294                 __MODULE_STRING(DEFAULT_HEARTBEAT));
 295
 296MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 297