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 <linux/device.h>
  28 #include <linux/clk.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 DEFINE_SPINLOCK(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 struct clk              *wdt_clk;
  74
  75 static void wdt_service(void)
  76 {
  77         spin_lock(&io_lock);
  78
  79         /* put watchdog in service state */
  80         iowrite32(WDKEY_SEQ0, wdt_base + WDTCR);
  81         /* put watchdog in active state */
  82         iowrite32(WDKEY_SEQ1, wdt_base + WDTCR);
  83
  84         spin_unlock(&io_lock);
  85 }
  86
  87 static void wdt_enable(void)
  88 {
  89         u32 tgcr;
  90         u32 timer_margin;
  91         unsigned long wdt_freq;
  92
  93         wdt_freq = clk_get_rate(wdt_clk);
  94
  95         spin_lock(&io_lock);
  96
  97         /* disable, internal clock source */
  98         iowrite32(0, wdt_base + TCR);
  99         /* reset timer, set mode to 64-bit watchdog, and unreset */
 100         iowrite32(0, wdt_base + TGCR);
 101         tgcr = TIMMODE_64BIT_WDOG | TIM12RS_UNRESET | TIM34RS_UNRESET;
 102         iowrite32(tgcr, wdt_base + TGCR);
 103         /* clear counter regs */
 104         iowrite32(0, wdt_base + TIM12);
 105         iowrite32(0, wdt_base + TIM34);
 106         /* set timeout period */
 107         timer_margin = (((u64)heartbeat * wdt_freq) & 0xffffffff);
 108         iowrite32(timer_margin, wdt_base + PRD12);
 109         timer_margin = (((u64)heartbeat * wdt_freq) >> 32);
 110         iowrite32(timer_margin, wdt_base + PRD34);
 111         /* enable run continuously */
 112         iowrite32(ENAMODE12_PERIODIC, wdt_base + TCR);
 113         /* Once the WDT is in pre-active state write to
 114          * TIM12, TIM34, PRD12, PRD34, TCR, TGCR, WDTCR are
 115          * write protected (except for the WDKEY field)
 116          */
 117         /* put watchdog in pre-active state */
 118         iowrite32(WDKEY_SEQ0 | WDEN, wdt_base + WDTCR);
 119         /* put watchdog in active state */
 120         iowrite32(WDKEY_SEQ1 | WDEN, wdt_base + WDTCR);
 121
 122         spin_unlock(&io_lock);
 123 }
 124
 125 static int davinci_wdt_open(struct inode *inode, struct file *file)
 126 {
 127         if (test_and_set_bit(WDT_IN_USE, &wdt_status))
 128                 return -EBUSY;
 129
 130         wdt_enable();
 131
 132         return nonseekable_open(inode, file);
 133 }
 134
 135 static ssize_t
 136 davinci_wdt_write(struct file *file, const char *data, size_t len,
 137                   loff_t *ppos)
 138 {
 139         if (len)
 140                 wdt_service();
 141
 142         return len;
 143 }
 144
 145 static struct watchdog_info ident = {
 146         .options = WDIOF_KEEPALIVEPING,
 147         .identity = "DaVinci Watchdog",
 148 };
 149
 150 static long davinci_wdt_ioctl(struct file *file,
 151                                         unsigned int cmd, unsigned long arg)
 152 {
 153         int ret = -ENOTTY;
 154
 155         switch (cmd) {
 156         case WDIOC_GETSUPPORT:
 157                 ret = copy_to_user((struct watchdog_info *)arg, &ident,
 158                                    sizeof(ident)) ? -EFAULT : 0;
 159                 break;
 160
 161         case WDIOC_GETSTATUS:
 162         case WDIOC_GETBOOTSTATUS:
 163                 ret = put_user(0, (int *)arg);
 164                 break;
 165
 166         case WDIOC_KEEPALIVE:
 167                 wdt_service();
 168                 ret = 0;
 169                 break;
 170
 171         case WDIOC_GETTIMEOUT:
 172                 ret = put_user(heartbeat, (int *)arg);
 173                 break;
 174         }
 175         return ret;
 176 }
 177
 178 static int davinci_wdt_release(struct inode *inode, struct file *file)
 179 {
 180         wdt_service();
 181         clear_bit(WDT_IN_USE, &wdt_status);
 182
 183         return 0;
 184 }
 185
 186 static const struct file_operations davinci_wdt_fops = {
 187         .owner = THIS_MODULE,
 188         .llseek = no_llseek,
 189         .write = davinci_wdt_write,
 190         .unlocked_ioctl = davinci_wdt_ioctl,
 191         .open = davinci_wdt_open,
 192         .release = davinci_wdt_release,
 193 };
 194
 195 static struct miscdevice davinci_wdt_miscdev = {
 196         .minor = WATCHDOG_MINOR,
 197         .name = "watchdog",
 198         .fops = &davinci_wdt_fops,
 199 };
 200
 201 static int __devinit davinci_wdt_probe(struct platform_device *pdev)
 202 {
 203         int ret = 0, size;
 204         struct resource *res;
 205         struct device *dev = &pdev->dev;
 206
 207         wdt_clk = clk_get(dev, NULL);
 208         if (WARN_ON(IS_ERR(wdt_clk)))
 209                 return PTR_ERR(wdt_clk);
 210
 211         clk_enable(wdt_clk);
 212
 213         if (heartbeat < 1 || heartbeat > MAX_HEARTBEAT)
 214                 heartbeat = DEFAULT_HEARTBEAT;
 215
 216         dev_info(dev, "heartbeat %d sec\n", heartbeat);
 217
 218         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 219         if (res == NULL) {
 220                 dev_err(dev, "failed to get memory region resource\n");
 221                 return -ENOENT;
 222         }
 223
 224         size = resource_size(res);
 225         wdt_mem = request_mem_region(res->start, size, pdev->name);
 226
 227         if (wdt_mem == NULL) {
 228                 dev_err(dev, "failed to get memory region\n");
 229                 return -ENOENT;
 230         }
 231
 232         wdt_base = ioremap(res->start, size);
 233         if (!wdt_base) {
 234                 dev_err(dev, "failed to map memory region\n");
 235                 return -ENOMEM;
 236         }
 237
 238         ret = misc_register(&davinci_wdt_miscdev);
 239         if (ret < 0) {
 240                 dev_err(dev, "cannot register misc device\n");
 241                 release_resource(wdt_mem);
 242                 kfree(wdt_mem);
 243         } else {
 244                 set_bit(WDT_DEVICE_INITED, &wdt_status);
 245         }
 246
 247         iounmap(wdt_base);
 248         return ret;
 249 }
 250
 251 static int __devexit davinci_wdt_remove(struct platform_device *pdev)
 252 {
 253         misc_deregister(&davinci_wdt_miscdev);
 254         if (wdt_mem) {
 255                 release_resource(wdt_mem);
 256                 kfree(wdt_mem);
 257                 wdt_mem = NULL;
 258         }
 259
 260         clk_disable(wdt_clk);
 261         clk_put(wdt_clk);
 262
 263         return 0;
 264 }
 265
 266 static struct platform_driver platform_wdt_driver = {
 267         .driver = {
 268                 .name = "watchdog",
 269                 .owner  = THIS_MODULE,
 270         },
 271         .probe = davinci_wdt_probe,
 272         .remove = __devexit_p(davinci_wdt_remove),
 273 };
 274
 275 static int __init davinci_wdt_init(void)
 276 {
 277         return platform_driver_register(&platform_wdt_driver);
 278 }
 279
 280 static void __exit davinci_wdt_exit(void)
 281 {
 282         platform_driver_unregister(&platform_wdt_driver);
 283 }
 284
 285 module_init(davinci_wdt_init);
 286 module_exit(davinci_wdt_exit);
 287
 288 MODULE_AUTHOR("Texas Instruments");
 289 MODULE_DESCRIPTION("DaVinci Watchdog Driver");
 290
 291 module_param(heartbeat, int, 0);
 292 MODULE_PARM_DESC(heartbeat,
 293                  "Watchdog heartbeat period in seconds from 1 to "
 294                  __MODULE_STRING(MAX_HEARTBEAT) ", default "
 295                  __MODULE_STRING(DEFAULT_HEARTBEAT));
 296
 297 MODULE_LICENSE("GPL");
 298 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 299 MODULE_ALIAS("platform:watchdog");