drivers/char/watchdog/at32ap700x_wdt.c

   1 /*
   2  * Watchdog driver for Atmel AT32AP700X devices
   3  *
   4  * Copyright (C) 2005-2006 Atmel Corporation
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10
  11 #include <linux/init.h>
  12 #include <linux/kernel.h>
  13 #include <linux/module.h>
  14 #include <linux/moduleparam.h>
  15 #include <linux/miscdevice.h>
  16 #include <linux/fs.h>
  17 #include <linux/platform_device.h>
  18 #include <linux/watchdog.h>
  19 #include <linux/uaccess.h>
  20 #include <linux/io.h>
  21
  22 #define TIMEOUT_MIN             1
  23 #define TIMEOUT_DEFAULT         CONFIG_AT32AP700X_WDT_TIMEOUT
  24 #define TIMEOUT_MAX             2
  25
  26 /* Watchdog registers and write/read macro */
  27 #define WDT_CTRL                0x00
  28 #define WDT_CTRL_EN                0
  29 #define WDT_CTRL_PSEL              8
  30 #define WDT_CTRL_KEY              24
  31
  32 #define WDT_CLR                 0x04
  33
  34 #define WDT_BIT(name)           (1 << WDT_##name)
  35 #define WDT_BF(name,value)      ((value) << WDT_##name)
  36
  37 #define wdt_readl(dev,reg)                              \
  38         __raw_readl((dev)->regs + WDT_##reg)
  39 #define wdt_writel(dev,reg,value)                       \
  40         __raw_writel((value), (dev)->regs + WDT_##reg)
  41
  42 struct wdt_at32ap700x {
  43         void __iomem            *regs;
  44         int                     timeout;
  45         int                     users;
  46         struct miscdevice       miscdev;
  47 };
  48
  49 static struct wdt_at32ap700x *wdt;
  50
  51 /*
  52  * Disable the watchdog.
  53  */
  54 static void inline at32_wdt_stop(void)
  55 {
  56         unsigned long psel = wdt_readl(wdt, CTRL) & WDT_BF(CTRL_PSEL, 0x0f);
  57         wdt_writel(wdt, CTRL, psel | WDT_BF(CTRL_KEY, 0x55));
  58         wdt_writel(wdt, CTRL, psel | WDT_BF(CTRL_KEY, 0xaa));
  59 }
  60
  61 /*
  62  * Enable and reset the watchdog.
  63  */
  64 static void inline at32_wdt_start(void)
  65 {
  66         /* 0xf is 2^16 divider = 2 sec, 0xe is 2^15 divider = 1 sec */
  67         unsigned long psel = (wdt->timeout > 1) ? 0xf : 0xe;
  68
  69         wdt_writel(wdt, CTRL, WDT_BIT(CTRL_EN)
  70                         | WDT_BF(CTRL_PSEL, psel)
  71                         | WDT_BF(CTRL_KEY, 0x55));
  72         wdt_writel(wdt, CTRL, WDT_BIT(CTRL_EN)
  73                         | WDT_BF(CTRL_PSEL, psel)
  74                         | WDT_BF(CTRL_KEY, 0xaa));
  75 }
  76
  77 /*
  78  * Pat the watchdog timer.
  79  */
  80 static void inline at32_wdt_pat(void)
  81 {
  82         wdt_writel(wdt, CLR, 0x42);
  83 }
  84
  85 /*
  86  * Watchdog device is opened, and watchdog starts running.
  87  */
  88 static int at32_wdt_open(struct inode *inode, struct file *file)
  89 {
  90         if (test_and_set_bit(1, &wdt->users))
  91                 return -EBUSY;
  92
  93         at32_wdt_start();
  94         return nonseekable_open(inode, file);
  95 }
  96
  97 /*
  98  * Close the watchdog device. If CONFIG_WATCHDOG_NOWAYOUT is _not_ defined then
  99  * the watchdog is also disabled.
 100  */
 101 static int at32_wdt_close(struct inode *inode, struct file *file)
 102 {
 103 #ifndef CONFIG_WATCHDOG_NOWAYOUT
 104         at32_wdt_stop();
 105 #endif
 106         clear_bit(1, &wdt->users);
 107         return 0;
 108 }
 109
 110 /*
 111  * Change the watchdog time interval.
 112  */
 113 static int at32_wdt_settimeout(int time)
 114 {
 115         /*
 116          * All counting occurs at 1 / SLOW_CLOCK (32 kHz) and max prescaler is
 117          * 2 ^ 16 allowing up to 2 seconds timeout.
 118          */
 119         if ((time < TIMEOUT_MIN) || (time > TIMEOUT_MAX))
 120                 return -EINVAL;
 121
 122         /*
 123          * Set new watchdog time. It will be used when at32_wdt_start() is
 124          * called.
 125          */
 126         wdt->timeout = time;
 127         return 0;
 128 }
 129
 130 static struct watchdog_info at32_wdt_info = {
 131         .identity       = "at32ap700x watchdog",
 132         .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 133 };
 134
 135 /*
 136  * Handle commands from user-space.
 137  */
 138 static int at32_wdt_ioctl(struct inode *inode, struct file *file,
 139                 unsigned int cmd, unsigned long arg)
 140 {
 141         int ret = -ENOTTY;
 142         int time;
 143         void __user *argp = (void __user *)arg;
 144         int __user *p = argp;
 145
 146         switch (cmd) {
 147         case WDIOC_KEEPALIVE:
 148                 at32_wdt_pat();
 149                 ret = 0;
 150                 break;
 151         case WDIOC_GETSUPPORT:
 152                 ret = copy_to_user(argp, &at32_wdt_info,
 153                                 sizeof(at32_wdt_info)) ? -EFAULT : 0;
 154                 break;
 155         case WDIOC_SETTIMEOUT:
 156                 ret = get_user(time, p);
 157                 if (ret)
 158                         break;
 159                 ret = at32_wdt_settimeout(time);
 160                 if (ret)
 161                         break;
 162                 /* Enable new time value */
 163                 at32_wdt_start();
 164                 /* fall through */
 165         case WDIOC_GETTIMEOUT:
 166                 ret = put_user(wdt->timeout, p);
 167                 break;
 168         case WDIOC_GETSTATUS: /* fall through */
 169         case WDIOC_GETBOOTSTATUS:
 170                 ret = put_user(0, p);
 171                 break;
 172         case WDIOC_SETOPTIONS:
 173                 ret = get_user(time, p);
 174                 if (ret)
 175                         break;
 176                 if (time & WDIOS_DISABLECARD)
 177                         at32_wdt_stop();
 178                 if (time & WDIOS_ENABLECARD)
 179                         at32_wdt_start();
 180                 ret = 0;
 181                 break;
 182         }
 183
 184         return ret;
 185 }
 186
 187 static ssize_t at32_wdt_write(struct file *file, const char *data, size_t len,
 188                                 loff_t *ppos)
 189 {
 190         at32_wdt_pat();
 191         return len;
 192 }
 193
 194 static const struct file_operations at32_wdt_fops = {
 195         .owner          = THIS_MODULE,
 196         .llseek         = no_llseek,
 197         .ioctl          = at32_wdt_ioctl,
 198         .open           = at32_wdt_open,
 199         .release        = at32_wdt_close,
 200         .write          = at32_wdt_write,
 201 };
 202
 203 static int __init at32_wdt_probe(struct platform_device *pdev)
 204 {
 205         struct resource *regs;
 206         int ret;
 207
 208         if (wdt) {
 209                 dev_dbg(&pdev->dev, "only 1 wdt instance supported.\n");
 210                 return -EBUSY;
 211         }
 212
 213         regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 214         if (!regs) {
 215                 dev_dbg(&pdev->dev, "missing mmio resource\n");
 216                 return -ENXIO;
 217         }
 218
 219         wdt = kzalloc(sizeof(struct wdt_at32ap700x), GFP_KERNEL);
 220         if (!wdt) {
 221                 dev_dbg(&pdev->dev, "no memory for wdt structure\n");
 222                 return -ENOMEM;
 223         }
 224
 225         wdt->regs = ioremap(regs->start, regs->end - regs->start + 1);
 226         wdt->users = 0;
 227         wdt->miscdev.minor = WATCHDOG_MINOR;
 228         wdt->miscdev.name = "watchdog";
 229         wdt->miscdev.fops = &at32_wdt_fops;
 230
 231         if (at32_wdt_settimeout(TIMEOUT_DEFAULT)) {
 232                 at32_wdt_settimeout(TIMEOUT_MAX);
 233                 dev_dbg(&pdev->dev,
 234                         "default timeout invalid, set to %d sec.\n",
 235                         TIMEOUT_MAX);
 236         }
 237
 238         ret = misc_register(&wdt->miscdev);
 239         if (ret) {
 240                 dev_dbg(&pdev->dev, "failed to register wdt miscdev\n");
 241                 goto err_register;
 242         }
 243
 244         platform_set_drvdata(pdev, wdt);
 245         wdt->miscdev.parent = &pdev->dev;
 246         dev_info(&pdev->dev, "AT32AP700X WDT at 0x%p\n", wdt->regs);
 247
 248         return 0;
 249
 250 err_register:
 251         kfree(wdt);
 252         wdt = NULL;
 253         return ret;
 254 }
 255
 256 static int __exit at32_wdt_remove(struct platform_device *pdev)
 257 {
 258         if (wdt && platform_get_drvdata(pdev) == wdt) {
 259                 misc_deregister(&wdt->miscdev);
 260                 kfree(wdt);
 261                 wdt = NULL;
 262                 platform_set_drvdata(pdev, NULL);
 263         }
 264
 265         return 0;
 266 }
 267
 268 static void at32_wdt_shutdown(struct platform_device *pdev)
 269 {
 270         at32_wdt_stop();
 271 }
 272
 273 #ifdef CONFIG_PM
 274 static int at32_wdt_suspend(struct platform_device *pdev, pm_message_t message)
 275 {
 276         at32_wdt_stop();
 277         return 0;
 278 }
 279
 280 static int at32_wdt_resume(struct platform_device *pdev)
 281 {
 282         if (wdt->users)
 283                 at32_wdt_start();
 284         return 0;
 285 }
 286 #endif
 287
 288 static struct platform_driver at32_wdt_driver = {
 289         .remove         = __exit_p(at32_wdt_remove),
 290 #ifdef CONFIG_PM
 291         .suspend        = at32_wdt_suspend,
 292         .resume         = at32_wdt_resume,
 293 #endif
 294         .driver         = {
 295                 .name   = "at32_wdt",
 296                 .owner  = THIS_MODULE,
 297         },
 298         .shutdown       = at32_wdt_shutdown,
 299 };
 300
 301 static int __init at32_wdt_init(void)
 302 {
 303         return platform_driver_probe(&at32_wdt_driver, at32_wdt_probe);
 304 }
 305 module_init(at32_wdt_init);
 306
 307 static void __exit at32_wdt_exit(void)
 308 {
 309         platform_driver_unregister(&at32_wdt_driver);
 310 }
 311 module_exit(at32_wdt_exit);
 312
 313 MODULE_AUTHOR("Hans-Christian Egtvedt <hcegtvedt@atmel.com>");
 314 MODULE_DESCRIPTION("Watchdog driver for Atmel AT32AP700X");
 315 MODULE_LICENSE("GPL");
 316 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);