LXR linux/drivers/watchdog/ks8695

   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
  41static int wdt_time = WDT_DEFAULT_TIME;
  42static bool nowayout = WATCHDOG_NOWAYOUT;
  43
  44module_param(wdt_time, int, 0);
  45MODULE_PARM_DESC(wdt_time, "Watchdog time in seconds. (default="
  46                                        __MODULE_STRING(WDT_DEFAULT_TIME) ")");
  47
  48#ifdef CONFIG_WATCHDOG_NOWAYOUT
  49module_param(nowayout, bool, 0);
  50MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  51                                __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  52#endif
  53
  54
  55static unsigned long ks8695wdt_busy;
  56static DEFINE_SPINLOCK(ks8695_lock);
  57
  58/* ......................................................................... */
  59
  60/*
  61 * Disable the watchdog.
  62 */
  63static 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 */
  77static 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 */
  99static 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 */
 114static 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 */
 136static 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 */
 150static 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
 159static 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 */
 167static 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 */
 211static 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
 220static 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
 229static struct miscdevice ks8695wdt_miscdev = {
 230        .minor          = WATCHDOG_MINOR,
 231        .name           = "watchdog",
 232        .fops           = &ks8695wdt_fops,
 233};
 234
 235static 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
 252static int ks8695wdt_remove(struct platform_device *pdev)
 253{
 254        misc_deregister(&ks8695wdt_miscdev);
 255        ks8695wdt_miscdev.parent = NULL;
 256
 257        return 0;
 258}
 259
 260static void ks8695wdt_shutdown(struct platform_device *pdev)
 261{
 262        ks8695_wdt_stop();
 263}
 264
 265#ifdef CONFIG_PM
 266
 267static int ks8695wdt_suspend(struct platform_device *pdev, pm_message_t message)
 268{
 269        ks8695_wdt_stop();
 270        return 0;
 271}
 272
 273static 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
 285static 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
 296static 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
 308static void __exit ks8695_wdt_exit(void)
 309{
 310        platform_driver_unregister(&ks8695wdt_driver);
 311}
 312
 313module_init(ks8695_wdt_init);
 314module_exit(ks8695_wdt_exit);
 315
 316MODULE_AUTHOR("Andrew Victor");
 317MODULE_DESCRIPTION("Watchdog driver for KS8695");
 318MODULE_LICENSE("GPL");
 319MODULE_ALIAS("platform:ks8695_wdt");
 320