drivers/watchdog/stmp3xxx_wdt.c

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