drivers/char/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
  26 #include <asm/hardware.h>
  27 #include <asm/uaccess.h>
  28 #include <asm/io.h>
  29
  30 #define MODULE_NAME "DAVINCI-WDT: "
  31
  32 #define DEFAULT_HEARTBEAT 60
  33 #define MAX_HEARTBEAT     600   /* really the max margin is 264/27MHz*/
  34
  35 /* Timer register set definition */
  36 #define PID12   (0x0)
  37 #define EMUMGT  (0x4)
  38 #define TIM12   (0x10)
  39 #define TIM34   (0x14)
  40 #define PRD12   (0x18)
  41 #define PRD34   (0x1C)
  42 #define TCR     (0x20)
  43 #define TGCR    (0x24)
  44 #define WDTCR   (0x28)
  45
  46 /* TCR bit definitions */
  47 #define ENAMODE12_DISABLED      (0 << 6)
  48 #define ENAMODE12_ONESHOT       (1 << 6)
  49 #define ENAMODE12_PERIODIC      (2 << 6)
  50
  51 /* TGCR bit definitions */
  52 #define TIM12RS_UNRESET         (1 << 0)
  53 #define TIM34RS_UNRESET         (1 << 1)
  54 #define TIMMODE_64BIT_WDOG      (2 << 2)
  55
  56 /* WDTCR bit definitions */
  57 #define WDEN                    (1 << 14)
  58 #define WDFLAG                  (1 << 15)
  59 #define WDKEY_SEQ0              (0xa5c6 << 16)
  60 #define WDKEY_SEQ1              (0xda7e << 16)
  61
  62 static int heartbeat = DEFAULT_HEARTBEAT;
  63
  64 static spinlock_t io_lock;
  65 static unsigned long wdt_status;
  66 #define WDT_IN_USE        0
  67 #define WDT_OK_TO_CLOSE   1
  68 #define WDT_REGION_INITED 2
  69 #define WDT_DEVICE_INITED 3
  70
  71 static struct resource  *wdt_mem;
  72 static void __iomem     *wdt_base;
  73
  74 static void wdt_service(void)
  75 {
  76         spin_lock(&io_lock);
  77
  78         /* put watchdog in service state */
  79         davinci_writel(WDKEY_SEQ0, wdt_base + WDTCR);
  80         /* put watchdog in active state */
  81         davinci_writel(WDKEY_SEQ1, wdt_base + WDTCR);
  82
  83         spin_unlock(&io_lock);
  84 }
  85
  86 static void wdt_enable(void)
  87 {
  88         u32 tgcr;
  89         u32 timer_margin;
  90
  91         spin_lock(&io_lock);
  92
  93         /* disable, internal clock source */
  94         davinci_writel(0, wdt_base + TCR);
  95         /* reset timer, set mode to 64-bit watchdog, and unreset */
  96         davinci_writel(0, wdt_base + TGCR);
  97         tgcr = TIMMODE_64BIT_WDOG | TIM12RS_UNRESET | TIM34RS_UNRESET;
  98         davinci_writel(tgcr, wdt_base + TGCR);
  99         /* clear counter regs */
 100         davinci_writel(0, wdt_base + TIM12);
 101         davinci_writel(0, wdt_base + TIM34);
 102         /* set timeout period */
 103         timer_margin = (((u64)heartbeat * CLOCK_TICK_RATE) & 0xffffffff);
 104         davinci_writel(timer_margin, wdt_base + PRD12);
 105         timer_margin = (((u64)heartbeat * CLOCK_TICK_RATE) >> 32);
 106         davinci_writel(timer_margin, wdt_base + PRD34);
 107         /* enable run continuously */
 108         davinci_writel(ENAMODE12_PERIODIC, wdt_base + TCR);
 109         /* Once the WDT is in pre-active state write to
 110          * TIM12, TIM34, PRD12, PRD34, TCR, TGCR, WDTCR are
 111          * write protected (except for the WDKEY field)
 112          */
 113         /* put watchdog in pre-active state */
 114         davinci_writel(WDKEY_SEQ0 | WDEN, wdt_base + WDTCR);
 115         /* put watchdog in active state */
 116         davinci_writel(WDKEY_SEQ1 | WDEN, wdt_base + WDTCR);
 117
 118         spin_unlock(&io_lock);
 119 }
 120
 121 static int davinci_wdt_open(struct inode *inode, struct file *file)
 122 {
 123         if (test_and_set_bit(WDT_IN_USE, &wdt_status))
 124                 return -EBUSY;
 125
 126         wdt_enable();
 127
 128         return nonseekable_open(inode, file);
 129 }
 130
 131 static ssize_t
 132 davinci_wdt_write(struct file *file, const char *data, size_t len,
 133                   loff_t *ppos)
 134 {
 135         if (len)
 136                 wdt_service();
 137
 138         return len;
 139 }
 140
 141 static struct watchdog_info ident = {
 142         .options = WDIOF_KEEPALIVEPING,
 143         .identity = "DaVinci Watchdog",
 144 };
 145
 146 static int
 147 davinci_wdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 148                   unsigned long arg)
 149 {
 150         int ret = -ENOTTY;
 151
 152         switch (cmd) {
 153         case WDIOC_GETSUPPORT:
 154                 ret = copy_to_user((struct watchdog_info *)arg, &ident,
 155                                    sizeof(ident)) ? -EFAULT : 0;
 156                 break;
 157
 158         case WDIOC_GETSTATUS:
 159         case WDIOC_GETBOOTSTATUS:
 160                 ret = put_user(0, (int *)arg);
 161                 break;
 162
 163         case WDIOC_GETTIMEOUT:
 164                 ret = put_user(heartbeat, (int *)arg);
 165                 break;
 166
 167         case WDIOC_KEEPALIVE:
 168                 wdt_service();
 169                 ret = 0;
 170                 break;
 171         }
 172         return ret;
 173 }
 174
 175 static int davinci_wdt_release(struct inode *inode, struct file *file)
 176 {
 177         wdt_service();
 178         clear_bit(WDT_IN_USE, &wdt_status);
 179
 180         return 0;
 181 }
 182
 183 static const struct file_operations davinci_wdt_fops = {
 184         .owner = THIS_MODULE,
 185         .llseek = no_llseek,
 186         .write = davinci_wdt_write,
 187         .ioctl = davinci_wdt_ioctl,
 188         .open = davinci_wdt_open,
 189         .release = davinci_wdt_release,
 190 };
 191
 192 static struct miscdevice davinci_wdt_miscdev = {
 193         .minor = WATCHDOG_MINOR,
 194         .name = "watchdog",
 195         .fops = &davinci_wdt_fops,
 196 };
 197
 198 static int davinci_wdt_probe(struct platform_device *pdev)
 199 {
 200         int ret = 0, size;
 201         struct resource *res;
 202
 203         spin_lock_init(&io_lock);
 204
 205         if (heartbeat < 1 || heartbeat > MAX_HEARTBEAT)
 206                 heartbeat = DEFAULT_HEARTBEAT;
 207
 208         printk(KERN_INFO MODULE_NAME
 209                 "DaVinci Watchdog Timer: heartbeat %d sec\n", heartbeat);
 210
 211         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 212         if (res == NULL) {
 213                 printk(KERN_INFO MODULE_NAME
 214                         "failed to get memory region resource\n");
 215                 return -ENOENT;
 216         }
 217
 218         size = res->end - res->start + 1;
 219         wdt_mem = request_mem_region(res->start, size, pdev->name);
 220
 221         if (wdt_mem == NULL) {
 222                 printk(KERN_INFO MODULE_NAME "failed to get memory region\n");
 223                 return -ENOENT;
 224         }
 225         wdt_base = (void __iomem *)(res->start);
 226
 227         ret = misc_register(&davinci_wdt_miscdev);
 228         if (ret < 0) {
 229                 printk(KERN_ERR MODULE_NAME "cannot register misc device\n");
 230                 release_resource(wdt_mem);
 231                 kfree(wdt_mem);
 232         } else {
 233                 set_bit(WDT_DEVICE_INITED, &wdt_status);
 234         }
 235
 236         return ret;
 237 }
 238
 239 static int davinci_wdt_remove(struct platform_device *pdev)
 240 {
 241         misc_deregister(&davinci_wdt_miscdev);
 242         if (wdt_mem) {
 243                 release_resource(wdt_mem);
 244                 kfree(wdt_mem);
 245                 wdt_mem = NULL;
 246         }
 247         return 0;
 248 }
 249
 250 static struct platform_driver platform_wdt_driver = {
 251         .driver = {
 252                 .name = "watchdog",
 253         },
 254         .probe = davinci_wdt_probe,
 255         .remove = davinci_wdt_remove,
 256 };
 257
 258 static int __init davinci_wdt_init(void)
 259 {
 260         return platform_driver_register(&platform_wdt_driver);
 261 }
 262
 263 static void __exit davinci_wdt_exit(void)
 264 {
 265         return platform_driver_unregister(&platform_wdt_driver);
 266 }
 267
 268 module_init(davinci_wdt_init);
 269 module_exit(davinci_wdt_exit);
 270
 271 MODULE_AUTHOR("Texas Instruments");
 272 MODULE_DESCRIPTION("DaVinci Watchdog Driver");
 273
 274 module_param(heartbeat, int, 0);
 275 MODULE_PARM_DESC(heartbeat,
 276                  "Watchdog heartbeat period in seconds from 1 to "
 277                  __MODULE_STRING(MAX_HEARTBEAT) ", default "
 278                  __MODULE_STRING(DEFAULT_HEARTBEAT));
 279
 280 MODULE_LICENSE("GPL");
 281 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);