LXR linux/drivers/watchdog/mpc5200

   1#include <linux/init.h>
   2#include <linux/module.h>
   3#include <linux/miscdevice.h>
   4#include <linux/watchdog.h>
   5#include <linux/io.h>
   6#include <linux/spinlock.h>
   7#include <asm/of_platform.h>
   8#include <asm/uaccess.h>
   9#include <asm/mpc52xx.h>
  10
  11
  12#define GPT_MODE_WDT            (1<<15)
  13#define GPT_MODE_CE             (1<<12)
  14#define GPT_MODE_MS_TIMER       (0x4)
  15
  16
  17struct mpc5200_wdt {
  18        unsigned count; /* timer ticks before watchdog kicks in */
  19        long ipb_freq;
  20        struct miscdevice miscdev;
  21        struct resource mem;
  22        struct mpc52xx_gpt __iomem *regs;
  23        spinlock_t io_lock;
  24};
  25
  26/* is_active stores wether or not the /dev/watchdog device is opened */
  27static unsigned long is_active;
  28
  29/* misc devices don't provide a way, to get back to 'dev' or 'miscdev' from
  30 * file operations, which sucks. But there can be max 1 watchdog anyway, so...
  31 */
  32static struct mpc5200_wdt *wdt_global;
  33
  34
  35/* helper to calculate timeout in timer counts */
  36static void mpc5200_wdt_set_timeout(struct mpc5200_wdt *wdt, int timeout)
  37{
  38        /* use biggest prescaler of 64k */
  39        wdt->count = (wdt->ipb_freq + 0xffff) / 0x10000 * timeout;
  40
  41        if (wdt->count > 0xffff)
  42                wdt->count = 0xffff;
  43}
  44/* return timeout in seconds (calculated from timer count) */
  45static int mpc5200_wdt_get_timeout(struct mpc5200_wdt *wdt)
  46{
  47        return wdt->count * 0x10000 / wdt->ipb_freq;
  48}
  49
  50
  51/* watchdog operations */
  52static int mpc5200_wdt_start(struct mpc5200_wdt *wdt)
  53{
  54        spin_lock(&wdt->io_lock);
  55        /* disable */
  56        out_be32(&wdt->regs->mode, 0);
  57        /* set timeout, with maximum prescaler */
  58        out_be32(&wdt->regs->count, 0x0 | wdt->count);
  59        /* enable watchdog */
  60        out_be32(&wdt->regs->mode, GPT_MODE_CE | GPT_MODE_WDT | GPT_MODE_MS_TIMER);
  61        spin_unlock(&wdt->io_lock);
  62
  63        return 0;
  64}
  65static int mpc5200_wdt_ping(struct mpc5200_wdt *wdt)
  66{
  67        spin_lock(&wdt->io_lock);
  68        /* writing A5 to OCPW resets the watchdog */
  69        out_be32(&wdt->regs->mode, 0xA5000000 | (0xffffff & in_be32(&wdt->regs->mode)));
  70        spin_unlock(&wdt->io_lock);
  71        return 0;
  72}
  73static int mpc5200_wdt_stop(struct mpc5200_wdt *wdt)
  74{
  75        spin_lock(&wdt->io_lock);
  76        /* disable */
  77        out_be32(&wdt->regs->mode, 0);
  78        spin_unlock(&wdt->io_lock);
  79        return 0;
  80}
  81
  82
  83/* file operations */
  84static ssize_t mpc5200_wdt_write(struct file *file, const char __user *data,
  85                size_t len, loff_t *ppos)
  86{
  87        struct mpc5200_wdt *wdt = file->private_data;
  88        mpc5200_wdt_ping(wdt);
  89        return 0;
  90}
  91static struct watchdog_info mpc5200_wdt_info = {
  92        .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
  93        .identity       = "mpc5200 watchdog on GPT0",
  94};
  95static int mpc5200_wdt_ioctl(struct inode *inode, struct file *file,
  96                unsigned int cmd, unsigned long arg)
  97{
  98        struct mpc5200_wdt *wdt = file->private_data;
  99        int __user *data = (int __user *)arg;
 100        int timeout;
 101        int ret = 0;
 102
 103        switch (cmd) {
 104        case WDIOC_GETSUPPORT:
 105                ret = copy_to_user(data, &mpc5200_wdt_info,
 106                        sizeof(mpc5200_wdt_info));
 107                if (ret)
 108                        ret = -EFAULT;
 109                break;
 110
 111        case WDIOC_GETSTATUS:
 112        case WDIOC_GETBOOTSTATUS:
 113                ret = put_user(0, data);
 114                break;
 115
 116        case WDIOC_KEEPALIVE:
 117                mpc5200_wdt_ping(wdt);
 118                break;
 119
 120        case WDIOC_SETTIMEOUT:
 121                ret = get_user(timeout, data);
 122                if (ret)
 123                        break;
 124                mpc5200_wdt_set_timeout(wdt, timeout);
 125                mpc5200_wdt_start(wdt);
 126                /* fall through and return the timeout */
 127
 128        case WDIOC_GETTIMEOUT:
 129                timeout = mpc5200_wdt_get_timeout(wdt);
 130                ret = put_user(timeout, data);
 131                break;
 132
 133        default:
 134                ret = -ENOTTY;
 135        }
 136        return ret;
 137}
 138static int mpc5200_wdt_open(struct inode *inode, struct file *file)
 139{
 140        /* /dev/watchdog can only be opened once */
 141        if (test_and_set_bit(0, &is_active))
 142                return -EBUSY;
 143
 144        /* Set and activate the watchdog */
 145        mpc5200_wdt_set_timeout(wdt_global, 30);
 146        mpc5200_wdt_start(wdt_global);
 147        file->private_data = wdt_global;
 148        return nonseekable_open(inode, file);
 149}
 150static int mpc5200_wdt_release(struct inode *inode, struct file *file)
 151{
 152#if WATCHDOG_NOWAYOUT == 0
 153        struct mpc5200_wdt *wdt = file->private_data;
 154        mpc5200_wdt_stop(wdt);
 155        wdt->count = 0;         /* == disabled */
 156#endif
 157        clear_bit(0, &is_active);
 158        return 0;
 159}
 160
 161static struct file_operations mpc5200_wdt_fops = {
 162        .owner  = THIS_MODULE,
 163        .write  = mpc5200_wdt_write,
 164        .ioctl  = mpc5200_wdt_ioctl,
 165        .open   = mpc5200_wdt_open,
 166        .release = mpc5200_wdt_release,
 167};
 168
 169/* module operations */
 170static int mpc5200_wdt_probe(struct of_device *op, const struct of_device_id *match)
 171{
 172        struct mpc5200_wdt *wdt;
 173        int err;
 174        const void *has_wdt;
 175        int size;
 176
 177        has_wdt = of_get_property(op->node, "has-wdt", NULL);
 178        if (!has_wdt)
 179                has_wdt = of_get_property(op->node, "fsl,has-wdt", NULL);
 180        if (!has_wdt)
 181                return -ENODEV;
 182
 183        wdt = kzalloc(sizeof(*wdt), GFP_KERNEL);
 184        if (!wdt)
 185                return -ENOMEM;
 186
 187        wdt->ipb_freq = mpc52xx_find_ipb_freq(op->node);
 188
 189        err = of_address_to_resource(op->node, 0, &wdt->mem);
 190        if (err)
 191                goto out_free;
 192        size = wdt->mem.end - wdt->mem.start + 1;
 193        if (!request_mem_region(wdt->mem.start, size, "mpc5200_wdt")) {
 194                err = -ENODEV;
 195                goto out_free;
 196        }
 197        wdt->regs = ioremap(wdt->mem.start, size);
 198        if (!wdt->regs) {
 199                err = -ENODEV;
 200                goto out_release;
 201        }
 202
 203        dev_set_drvdata(&op->dev, wdt);
 204        spin_lock_init(&wdt->io_lock);
 205
 206        wdt->miscdev = (struct miscdevice) {
 207                .minor  = WATCHDOG_MINOR,
 208                .name   = "watchdog",
 209                .fops   = &mpc5200_wdt_fops,
 210                .parent = &op->dev,
 211        };
 212        wdt_global = wdt;
 213        err = misc_register(&wdt->miscdev);
 214        if (!err)
 215                return 0;
 216
 217        iounmap(wdt->regs);
 218 out_release:
 219        release_mem_region(wdt->mem.start, size);
 220 out_free:
 221        kfree(wdt);
 222        return err;
 223}
 224
 225static int mpc5200_wdt_remove(struct of_device *op)
 226{
 227        struct mpc5200_wdt *wdt = dev_get_drvdata(&op->dev);
 228
 229        mpc5200_wdt_stop(wdt);
 230        misc_deregister(&wdt->miscdev);
 231        iounmap(wdt->regs);
 232        release_mem_region(wdt->mem.start, wdt->mem.end - wdt->mem.start + 1);
 233        kfree(wdt);
 234
 235        return 0;
 236}
 237static int mpc5200_wdt_suspend(struct of_device *op, pm_message_t state)
 238{
 239        struct mpc5200_wdt *wdt = dev_get_drvdata(&op->dev);
 240        mpc5200_wdt_stop(wdt);
 241        return 0;
 242}
 243static int mpc5200_wdt_resume(struct of_device *op)
 244{
 245        struct mpc5200_wdt *wdt = dev_get_drvdata(&op->dev);
 246        if (wdt->count)
 247                mpc5200_wdt_start(wdt);
 248        return 0;
 249}
 250static int mpc5200_wdt_shutdown(struct of_device *op)
 251{
 252        struct mpc5200_wdt *wdt = dev_get_drvdata(&op->dev);
 253        mpc5200_wdt_stop(wdt);
 254        return 0;
 255}
 256
 257static struct of_device_id mpc5200_wdt_match[] = {
 258        { .compatible = "mpc5200-gpt", },
 259        { .compatible = "fsl,mpc5200-gpt", },
 260        {},
 261};
 262static struct of_platform_driver mpc5200_wdt_driver = {
 263        .owner          = THIS_MODULE,
 264        .name           = "mpc5200-gpt-wdt",
 265        .match_table    = mpc5200_wdt_match,
 266        .probe          = mpc5200_wdt_probe,
 267        .remove         = mpc5200_wdt_remove,
 268        .suspend        = mpc5200_wdt_suspend,
 269        .resume         = mpc5200_wdt_resume,
 270        .shutdown       = mpc5200_wdt_shutdown,
 271};
 272
 273
 274static int __init mpc5200_wdt_init(void)
 275{
 276        return of_register_platform_driver(&mpc5200_wdt_driver);
 277}
 278
 279static void __exit mpc5200_wdt_exit(void)
 280{
 281        of_unregister_platform_driver(&mpc5200_wdt_driver);
 282}
 283
 284module_init(mpc5200_wdt_init);
 285module_exit(mpc5200_wdt_exit);
 286
 287MODULE_AUTHOR("Domen Puncer <domen.puncer@telargo.com>");
 288MODULE_LICENSE("Dual BSD/GPL");
 289MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 290