drivers/watchdog/davinci_wdt.c

   1 /*
   2  * drivers/char/watchdog/davinci_wdt.c
   3  *
   4  * Watchdog driver for DaVinci DM644x/DM646x processors
   5  *
   6  * Copyright (C) 2006 Texas Instruments.
   7  *
   8  * 2007 (c) MontaVista Software, Inc. This file is licensed under
   9  * the terms of the GNU General Public License version 2. This program
  10  * is licensed "as is" without any warranty of any kind, whether express
  11  * or implied.
  12  */
  13
  14 #include <linux/module.h>
  15 #include <linux/moduleparam.h>
  16 #include <linux/types.h>
  17 #include <linux/kernel.h>
  18 #include <linux/fs.h>
  19 #include <linux/miscdevice.h>
  20 #include <linux/watchdog.h>
  21 #include <linux/init.h>
  22 #include <linux/bitops.h>
  23 #include <linux/platform_device.h>
  24 #include <linux/spinlock.h>
  25 #include <linux/uaccess.h>
  26 #include <linux/io.h>
  27 #include <mach/hardware.h>
  28
  29 #define MODULE_NAME "DAVINCI-WDT: "
  30
  31 #define DEFAULT_HEARTBEAT 60
  32 #define MAX_HEARTBEAT     600   /* really the max margin is 264/27MHz*/
  33
  34 /* Timer register set definition */
  35 #define PID12   (0x0)
  36 #define EMUMGT  (0x4)
  37 #define TIM12   (0x10)
  38 #define TIM34   (0x14)
  39 #define PRD12   (0x18)
  40 #define PRD34   (0x1C)
  41 #define TCR     (0x20)
  42 #define TGCR    (0x24)
  43 #define WDTCR   (0x28)
  44
  45 /* TCR bit definitions */
  46 #define ENAMODE12_DISABLED      (0 << 6)
  47 #define ENAMODE12_ONESHOT       (1 << 6)
  48 #define ENAMODE12_PERIODIC      (2 << 6)
  49
  50 /* TGCR bit definitions */
  51 #define TIM12RS_UNRESET         (1 << 0)
  52 #define TIM34RS_UNRESET         (1 << 1)
  53 #define TIMMODE_64BIT_WDOG      (2 << 2)
  54
  55 /* WDTCR bit definitions */
  56 #define WDEN                    (1 << 14)
  57 #define WDFLAG                  (1 << 15)
  58 #define WDKEY_SEQ0              (0xa5c6 << 16)
  59 #define WDKEY_SEQ1              (0xda7e << 16)
  60
  61 static int heartbeat = DEFAULT_HEARTBEAT;
  62
  63 static DEFINE_SPINLOCK(io_lock);
  64 static unsigned long wdt_status;
  65 #define WDT_IN_USE        0
  66 #define WDT_OK_TO_CLOSE   1
  67 #define WDT_REGION_INITED 2
  68 #define WDT_DEVICE_INITED 3
  69
  70 static struct resource  *wdt_mem;
  71 static void __iomem     *wdt_base;
  72
  73 static void wdt_service(void)
  74 {
  75         spin_lock(&io_lock);
  76
  77         /* put watchdog in service state */
  78         davinci_writel(WDKEY_SEQ0, wdt_base + WDTCR);
  79         /* put watchdog in active state */
  80         davinci_writel(WDKEY_SEQ1, wdt_base + WDTCR);
  81
  82         spin_unlock(&io_lock);
  83 }
  84
  85 static void wdt_enable(void)
  86 {
  87         u32 tgcr;
  88         u32 timer_margin;
  89
  90         spin_lock(&io_lock);
  91
  92         /* disable, internal clock source */
  93         davinci_writel(0, wdt_base + TCR);
  94         /* reset timer, set mode to 64-bit watchdog, and unreset */
  95         davinci_writel(0, wdt_base + TGCR);
  96         tgcr = TIMMODE_64BIT_WDOG | TIM12RS_UNRESET | TIM34RS_UNRESET;
  97         davinci_writel(tgcr, wdt_base + TGCR);
  98         /* clear counter regs */
  99         davinci_writel(0, wdt_base + TIM12);
 100         davinci_writel(0, wdt_base + TIM34);
 101         /* set timeout period */
 102         timer_margin = (((u64)heartbeat * CLOCK_TICK_RATE) & 0xffffffff);
 103         davinci_writel(timer_margin, wdt_base + PRD12);
 104         timer_margin = (((u64)heartbeat * CLOCK_TICK_RATE) >> 32);
 105         davinci_writel(timer_margin, wdt_base + PRD34);
 106         /* enable run continuously */
 107         davinci_writel(ENAMODE12_PERIODIC, wdt_base + TCR);
 108         /* Once the WDT is in pre-active state write to
 109          * TIM12, TIM34, PRD12, PRD34, TCR, TGCR, WDTCR are
 110          * write protected (except for the WDKEY field)
 111          */
 112         /* put watchdog in pre-active state */
 113         davinci_writel(WDKEY_SEQ0 | WDEN, wdt_base + WDTCR);
 114         /* put watchdog in active state */
 115         davinci_writel(WDKEY_SEQ1 | WDEN, wdt_base + WDTCR);
 116
 117         spin_unlock(&io_lock);
 118 }
 119
 120 static int davinci_wdt_open(struct inode *inode, struct file *file)
 121 {
 122         if (test_and_set_bit(WDT_IN_USE, &wdt_status))
 123                 return -EBUSY;
 124
 125         wdt_enable();
 126
 127         return nonseekable_open(inode, file);
 128 }
 129
 130 static ssize_t
 131 davinci_wdt_write(struct file *file, const char *data, size_t len,
 132                   loff_t *ppos)
 133 {
 134         if (len)
 135                 wdt_service();
 136
 137         return len;
 138 }
 139
 140 static struct watchdog_info ident = {
 141         .options = WDIOF_KEEPALIVEPING,
 142         .identity = "DaVinci Watchdog",
 143 };
 144
 145 static long davinci_wdt_ioctl(struct file *file,
 146                                         unsigned int cmd, unsigned long arg)
 147 {
 148         int ret = -ENOTTY;
 149
 150         switch (cmd) {
 151         case WDIOC_GETSUPPORT:
 152                 ret = copy_to_user((struct watchdog_info *)arg, &ident,
 153                                    sizeof(ident)) ? -EFAULT : 0;
 154                 break;
 155
 156         case WDIOC_GETSTATUS:
 157         case WDIOC_GETBOOTSTATUS:
 158                 ret = put_user(0, (int *)arg);
 159                 break;
 160
 161         case WDIOC_KEEPALIVE:
 162                 wdt_service();
 163                 ret = 0;
 164                 break;
 165
 166         case WDIOC_GETTIMEOUT:
 167                 ret = put_user(heartbeat, (int *)arg);
 168                 break;
 169         }
 170         return ret;
 171 }
 172
 173 static int davinci_wdt_release(struct inode *inode, struct file *file)
 174 {
 175         wdt_service();
 176         clear_bit(WDT_IN_USE, &wdt_status);
 177
 178         return 0;
 179 }
 180
 181 static const struct file_operations davinci_wdt_fops = {
 182         .owner = THIS_MODULE,
 183         .llseek = no_llseek,
 184         .write = davinci_wdt_write,
 185         .unlocked_ioctl = davinci_wdt_ioctl,
 186         .open = davinci_wdt_open,
 187         .release = davinci_wdt_release,
 188 };
 189
 190 static struct miscdevice davinci_wdt_miscdev = {
 191         .minor = WATCHDOG_MINOR,
 192         .name = "watchdog",
 193         .fops = &davinci_wdt_fops,
 194 };
 195
 196 static int davinci_wdt_probe(struct platform_device *pdev)
 197 {
 198         int ret = 0, size;
 199         struct resource *res;
 200
 201         if (heartbeat < 1 || heartbeat > MAX_HEARTBEAT)
 202                 heartbeat = DEFAULT_HEARTBEAT;
 203
 204         printk(KERN_INFO MODULE_NAME
 205                 "DaVinci Watchdog Timer: heartbeat %d sec\n", heartbeat);
 206
 207         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 208         if (res == NULL) {
 209                 printk(KERN_INFO MODULE_NAME
 210                         "failed to get memory region resource\n");
 211                 return -ENOENT;
 212         }
 213
 214         size = res->end - res->start + 1;
 215         wdt_mem = request_mem_region(res->start, size, pdev->name);
 216
 217         if (wdt_mem == NULL) {
 218                 printk(KERN_INFO MODULE_NAME "failed to get memory region\n");
 219                 return -ENOENT;
 220         }
 221         wdt_base = (void __iomem *)(res->start);
 222
 223         ret = misc_register(&davinci_wdt_miscdev);
 224         if (ret < 0) {
 225                 printk(KERN_ERR MODULE_NAME "cannot register misc device\n");
 226                 release_resource(wdt_mem);
 227                 kfree(wdt_mem);
 228         } else {
 229                 set_bit(WDT_DEVICE_INITED, &wdt_status);
 230         }
 231
 232         return ret;
 233 }
 234
 235 static int davinci_wdt_remove(struct platform_device *pdev)
 236 {
 237         misc_deregister(&davinci_wdt_miscdev);
 238         if (wdt_mem) {
 239                 release_resource(wdt_mem);
 240                 kfree(wdt_mem);
 241                 wdt_mem = NULL;
 242         }
 243         return 0;
 244 }
 245
 246 static struct platform_driver platform_wdt_driver = {
 247         .driver = {
 248                 .name = "watchdog",
 249                 .owner  = THIS_MODULE,
 250         },
 251         .probe = davinci_wdt_probe,
 252         .remove = davinci_wdt_remove,
 253 };
 254
 255 static int __init davinci_wdt_init(void)
 256 {
 257         return platform_driver_register(&platform_wdt_driver);
 258 }
 259
 260 static void __exit davinci_wdt_exit(void)
 261 {
 262         platform_driver_unregister(&platform_wdt_driver);
 263 }
 264
 265 module_init(davinci_wdt_init);
 266 module_exit(davinci_wdt_exit);
 267
 268 MODULE_AUTHOR("Texas Instruments");
 269 MODULE_DESCRIPTION("DaVinci Watchdog Driver");
 270
 271 module_param(heartbeat, int, 0);
 272 MODULE_PARM_DESC(heartbeat,
 273                  "Watchdog heartbeat period in seconds from 1 to "
 274                  __MODULE_STRING(MAX_HEARTBEAT) ", default "
 275                  __MODULE_STRING(DEFAULT_HEARTBEAT));
 276
 277 MODULE_LICENSE("GPL");
 278 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 279 MODULE_ALIAS("platform:watchdog");