drivers/watchdog/ks8695_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Watchdog driver for Kendin/Micrel KS8695.
   4  *
   5  * (C) 2007 Andrew Victor
   6  */
   7
   8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   9
  10 #include <linux/bitops.h>
  11 #include <linux/errno.h>
  12 #include <linux/fs.h>
  13 #include <linux/init.h>
  14 #include <linux/kernel.h>
  15 #include <linux/miscdevice.h>
  16 #include <linux/module.h>
  17 #include <linux/moduleparam.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/types.h>
  20 #include <linux/watchdog.h>
  21 #include <linux/io.h>
  22 #include <linux/uaccess.h>
  23 #include <mach/hardware.h>
  24
  25 #define KS8695_TMR_OFFSET       (0xF0000 + 0xE400)
  26 #define KS8695_TMR_VA           (KS8695_IO_VA + KS8695_TMR_OFFSET)
  27
  28 /*
  29  * Timer registers
  30  */
  31 #define KS8695_TMCON            (0x00)          /* Timer Control Register */
  32 #define KS8695_T0TC             (0x08)          /* Timer 0 Timeout Count Register */
  33 #define TMCON_T0EN              (1 << 0)        /* Timer 0 Enable */
  34
  35 /* Timer0 Timeout Counter Register */
  36 #define T0TC_WATCHDOG           (0xff)          /* Enable watchdog mode */
  37
  38 #define WDT_DEFAULT_TIME        5       /* seconds */
  39 #define WDT_MAX_TIME            171     /* seconds */
  40
  41 static int wdt_time = WDT_DEFAULT_TIME;
  42 static bool nowayout = WATCHDOG_NOWAYOUT;
  43
  44 module_param(wdt_time, int, 0);
  45 MODULE_PARM_DESC(wdt_time, "Watchdog time in seconds. (default="
  46                                         __MODULE_STRING(WDT_DEFAULT_TIME) ")");
  47
  48 #ifdef CONFIG_WATCHDOG_NOWAYOUT
  49 module_param(nowayout, bool, 0);
  50 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  51                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  52 #endif
  53
  54
  55 static unsigned long ks8695wdt_busy;
  56 static DEFINE_SPINLOCK(ks8695_lock);
  57
  58 /* ......................................................................... */
  59
  60 /*
  61  * Disable the watchdog.
  62  */
  63 static inline void ks8695_wdt_stop(void)
  64 {
  65         unsigned long tmcon;
  66
  67         spin_lock(&ks8695_lock);
  68         /* disable timer0 */
  69         tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
  70         __raw_writel(tmcon & ~TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
  71         spin_unlock(&ks8695_lock);
  72 }
  73
  74 /*
  75  * Enable and reset the watchdog.
  76  */
  77 static inline void ks8695_wdt_start(void)
  78 {
  79         unsigned long tmcon;
  80         unsigned long tval = wdt_time * KS8695_CLOCK_RATE;
  81
  82         spin_lock(&ks8695_lock);
  83         /* disable timer0 */
  84         tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
  85         __raw_writel(tmcon & ~TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
  86
  87         /* program timer0 */
  88         __raw_writel(tval | T0TC_WATCHDOG, KS8695_TMR_VA + KS8695_T0TC);
  89
  90         /* re-enable timer0 */
  91         tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
  92         __raw_writel(tmcon | TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
  93         spin_unlock(&ks8695_lock);
  94 }
  95
  96 /*
  97  * Reload the watchdog timer.  (ie, pat the watchdog)
  98  */
  99 static inline void ks8695_wdt_reload(void)
 100 {
 101         unsigned long tmcon;
 102
 103         spin_lock(&ks8695_lock);
 104         /* disable, then re-enable timer0 */
 105         tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
 106         __raw_writel(tmcon & ~TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
 107         __raw_writel(tmcon | TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
 108         spin_unlock(&ks8695_lock);
 109 }
 110
 111 /*
 112  * Change the watchdog time interval.
 113  */
 114 static int ks8695_wdt_settimeout(int new_time)
 115 {
 116         /*
 117          * All counting occurs at KS8695_CLOCK_RATE / 128 = 0.256 Hz
 118          *
 119          * Since WDV is a 16-bit counter, the maximum period is
 120          * 65536 / 0.256 = 256 seconds.
 121          */
 122         if ((new_time <= 0) || (new_time > WDT_MAX_TIME))
 123                 return -EINVAL;
 124
 125         /* Set new watchdog time. It will be used when
 126            ks8695_wdt_start() is called. */
 127         wdt_time = new_time;
 128         return 0;
 129 }
 130
 131 /* ......................................................................... */
 132
 133 /*
 134  * Watchdog device is opened, and watchdog starts running.
 135  */
 136 static int ks8695_wdt_open(struct inode *inode, struct file *file)
 137 {
 138         if (test_and_set_bit(0, &ks8695wdt_busy))
 139                 return -EBUSY;
 140
 141         ks8695_wdt_start();
 142         return stream_open(inode, file);
 143 }
 144
 145 /*
 146  * Close the watchdog device.
 147  * If CONFIG_WATCHDOG_NOWAYOUT is NOT defined then the watchdog is also
 148  *  disabled.
 149  */
 150 static int ks8695_wdt_close(struct inode *inode, struct file *file)
 151 {
 152         /* Disable the watchdog when file is closed */
 153         if (!nowayout)
 154                 ks8695_wdt_stop();
 155         clear_bit(0, &ks8695wdt_busy);
 156         return 0;
 157 }
 158
 159 static const struct watchdog_info ks8695_wdt_info = {
 160         .identity       = "ks8695 watchdog",
 161         .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 162 };
 163
 164 /*
 165  * Handle commands from user-space.
 166  */
 167 static long ks8695_wdt_ioctl(struct file *file, unsigned int cmd,
 168                                                         unsigned long arg)
 169 {
 170         void __user *argp = (void __user *)arg;
 171         int __user *p = argp;
 172         int new_value;
 173
 174         switch (cmd) {
 175         case WDIOC_GETSUPPORT:
 176                 return copy_to_user(argp, &ks8695_wdt_info,
 177                                         sizeof(ks8695_wdt_info)) ? -EFAULT : 0;
 178         case WDIOC_GETSTATUS:
 179         case WDIOC_GETBOOTSTATUS:
 180                 return put_user(0, p);
 181         case WDIOC_SETOPTIONS:
 182                 if (get_user(new_value, p))
 183                         return -EFAULT;
 184                 if (new_value & WDIOS_DISABLECARD)
 185                         ks8695_wdt_stop();
 186                 if (new_value & WDIOS_ENABLECARD)
 187                         ks8695_wdt_start();
 188                 return 0;
 189         case WDIOC_KEEPALIVE:
 190                 ks8695_wdt_reload();    /* pat the watchdog */
 191                 return 0;
 192         case WDIOC_SETTIMEOUT:
 193                 if (get_user(new_value, p))
 194                         return -EFAULT;
 195                 if (ks8695_wdt_settimeout(new_value))
 196                         return -EINVAL;
 197                 /* Enable new time value */
 198                 ks8695_wdt_start();
 199                 /* Return current value */
 200                 return put_user(wdt_time, p);
 201         case WDIOC_GETTIMEOUT:
 202                 return put_user(wdt_time, p);
 203         default:
 204                 return -ENOTTY;
 205         }
 206 }
 207
 208 /*
 209  * Pat the watchdog whenever device is written to.
 210  */
 211 static ssize_t ks8695_wdt_write(struct file *file, const char *data,
 212                                                 size_t len, loff_t *ppos)
 213 {
 214         ks8695_wdt_reload();            /* pat the watchdog */
 215         return len;
 216 }
 217
 218 /* ......................................................................... */
 219
 220 static const struct file_operations ks8695wdt_fops = {
 221         .owner          = THIS_MODULE,
 222         .llseek         = no_llseek,
 223         .unlocked_ioctl = ks8695_wdt_ioctl,
 224         .open           = ks8695_wdt_open,
 225         .release        = ks8695_wdt_close,
 226         .write          = ks8695_wdt_write,
 227 };
 228
 229 static struct miscdevice ks8695wdt_miscdev = {
 230         .minor          = WATCHDOG_MINOR,
 231         .name           = "watchdog",
 232         .fops           = &ks8695wdt_fops,
 233 };
 234
 235 static int ks8695wdt_probe(struct platform_device *pdev)
 236 {
 237         int res;
 238
 239         if (ks8695wdt_miscdev.parent)
 240                 return -EBUSY;
 241         ks8695wdt_miscdev.parent = &pdev->dev;
 242
 243         res = misc_register(&ks8695wdt_miscdev);
 244         if (res)
 245                 return res;
 246
 247         pr_info("KS8695 Watchdog Timer enabled (%d seconds%s)\n",
 248                 wdt_time, nowayout ? ", nowayout" : "");
 249         return 0;
 250 }
 251
 252 static int ks8695wdt_remove(struct platform_device *pdev)
 253 {
 254         misc_deregister(&ks8695wdt_miscdev);
 255         ks8695wdt_miscdev.parent = NULL;
 256
 257         return 0;
 258 }
 259
 260 static void ks8695wdt_shutdown(struct platform_device *pdev)
 261 {
 262         ks8695_wdt_stop();
 263 }
 264
 265 #ifdef CONFIG_PM
 266
 267 static int ks8695wdt_suspend(struct platform_device *pdev, pm_message_t message)
 268 {
 269         ks8695_wdt_stop();
 270         return 0;
 271 }
 272
 273 static int ks8695wdt_resume(struct platform_device *pdev)
 274 {
 275         if (ks8695wdt_busy)
 276                 ks8695_wdt_start();
 277         return 0;
 278 }
 279
 280 #else
 281 #define ks8695wdt_suspend NULL
 282 #define ks8695wdt_resume        NULL
 283 #endif
 284
 285 static struct platform_driver ks8695wdt_driver = {
 286         .probe          = ks8695wdt_probe,
 287         .remove         = ks8695wdt_remove,
 288         .shutdown       = ks8695wdt_shutdown,
 289         .suspend        = ks8695wdt_suspend,
 290         .resume         = ks8695wdt_resume,
 291         .driver         = {
 292                 .name   = "ks8695_wdt",
 293         },
 294 };
 295
 296 static int __init ks8695_wdt_init(void)
 297 {
 298         /* Check that the heartbeat value is within range;
 299            if not reset to the default */
 300         if (ks8695_wdt_settimeout(wdt_time)) {
 301                 ks8695_wdt_settimeout(WDT_DEFAULT_TIME);
 302                 pr_info("ks8695_wdt: wdt_time value must be 1 <= wdt_time <= %i"
 303                                         ", using %d\n", wdt_time, WDT_MAX_TIME);
 304         }
 305         return platform_driver_register(&ks8695wdt_driver);
 306 }
 307
 308 static void __exit ks8695_wdt_exit(void)
 309 {
 310         platform_driver_unregister(&ks8695wdt_driver);
 311 }
 312
 313 module_init(ks8695_wdt_init);
 314 module_exit(ks8695_wdt_exit);
 315
 316 MODULE_AUTHOR("Andrew Victor");
 317 MODULE_DESCRIPTION("Watchdog driver for KS8695");
 318 MODULE_LICENSE("GPL");
 319 MODULE_ALIAS("platform:ks8695_wdt");