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 #include <linux/slab.h>
  30 #include <linux/err.h>
  31
  32 #define MODULE_NAME "DAVINCI-WDT: "
  33
  34 #define DEFAULT_HEARTBEAT 60
  35 #define MAX_HEARTBEAT     600   /* really the max margin is 264/27MHz*/
  36
  37 /* Timer register set definition */
  38 #define PID12   (0x0)
  39 #define EMUMGT  (0x4)
  40 #define TIM12   (0x10)
  41 #define TIM34   (0x14)
  42 #define PRD12   (0x18)
  43 #define PRD34   (0x1C)
  44 #define TCR     (0x20)
  45 #define TGCR    (0x24)
  46 #define WDTCR   (0x28)
  47
  48 /* TCR bit definitions */
  49 #define ENAMODE12_DISABLED      (0 << 6)
  50 #define ENAMODE12_ONESHOT       (1 << 6)
  51 #define ENAMODE12_PERIODIC      (2 << 6)
  52
  53 /* TGCR bit definitions */
  54 #define TIM12RS_UNRESET         (1 << 0)
  55 #define TIM34RS_UNRESET         (1 << 1)
  56 #define TIMMODE_64BIT_WDOG      (2 << 2)
  57
  58 /* WDTCR bit definitions */
  59 #define WDEN                    (1 << 14)
  60 #define WDFLAG                  (1 << 15)
  61 #define WDKEY_SEQ0              (0xa5c6 << 16)
  62 #define WDKEY_SEQ1              (0xda7e << 16)
  63
  64 static int heartbeat = DEFAULT_HEARTBEAT;
  65
  66 static DEFINE_SPINLOCK(io_lock);
  67 static unsigned long wdt_status;
  68 #define WDT_IN_USE        0
  69 #define WDT_OK_TO_CLOSE   1
  70 #define WDT_REGION_INITED 2
  71 #define WDT_DEVICE_INITED 3
  72
  73 static void __iomem     *wdt_base;
  74 struct clk              *wdt_clk;
  75
  76 static void wdt_service(void)
  77 {
  78         spin_lock(&io_lock);
  79
  80         /* put watchdog in service state */
  81         iowrite32(WDKEY_SEQ0, wdt_base + WDTCR);
  82         /* put watchdog in active state */
  83         iowrite32(WDKEY_SEQ1, wdt_base + WDTCR);
  84
  85         spin_unlock(&io_lock);
  86 }
  87
  88 static void wdt_enable(void)
  89 {
  90         u32 tgcr;
  91         u32 timer_margin;
  92         unsigned long wdt_freq;
  93
  94         wdt_freq = clk_get_rate(wdt_clk);
  95
  96         spin_lock(&io_lock);
  97
  98         /* disable, internal clock source */
  99         iowrite32(0, wdt_base + TCR);
 100         /* reset timer, set mode to 64-bit watchdog, and unreset */
 101         iowrite32(0, wdt_base + TGCR);
 102         tgcr = TIMMODE_64BIT_WDOG | TIM12RS_UNRESET | TIM34RS_UNRESET;
 103         iowrite32(tgcr, wdt_base + TGCR);
 104         /* clear counter regs */
 105         iowrite32(0, wdt_base + TIM12);
 106         iowrite32(0, wdt_base + TIM34);
 107         /* set timeout period */
 108         timer_margin = (((u64)heartbeat * wdt_freq) & 0xffffffff);
 109         iowrite32(timer_margin, wdt_base + PRD12);
 110         timer_margin = (((u64)heartbeat * wdt_freq) >> 32);
 111         iowrite32(timer_margin, wdt_base + PRD34);
 112         /* enable run continuously */
 113         iowrite32(ENAMODE12_PERIODIC, wdt_base + TCR);
 114         /* Once the WDT is in pre-active state write to
 115          * TIM12, TIM34, PRD12, PRD34, TCR, TGCR, WDTCR are
 116          * write protected (except for the WDKEY field)
 117          */
 118         /* put watchdog in pre-active state */
 119         iowrite32(WDKEY_SEQ0 | WDEN, wdt_base + WDTCR);
 120         /* put watchdog in active state */
 121         iowrite32(WDKEY_SEQ1 | WDEN, wdt_base + WDTCR);
 122
 123         spin_unlock(&io_lock);
 124 }
 125
 126 static int davinci_wdt_open(struct inode *inode, struct file *file)
 127 {
 128         if (test_and_set_bit(WDT_IN_USE, &wdt_status))
 129                 return -EBUSY;
 130
 131         wdt_enable();
 132
 133         return nonseekable_open(inode, file);
 134 }
 135
 136 static ssize_t
 137 davinci_wdt_write(struct file *file, const char *data, size_t len,
 138                   loff_t *ppos)
 139 {
 140         if (len)
 141                 wdt_service();
 142
 143         return len;
 144 }
 145
 146 static const struct watchdog_info ident = {
 147         .options = WDIOF_KEEPALIVEPING,
 148         .identity = "DaVinci Watchdog",
 149 };
 150
 151 static long davinci_wdt_ioctl(struct file *file,
 152                                         unsigned int cmd, unsigned long arg)
 153 {
 154         int ret = -ENOTTY;
 155
 156         switch (cmd) {
 157         case WDIOC_GETSUPPORT:
 158                 ret = copy_to_user((struct watchdog_info *)arg, &ident,
 159                                    sizeof(ident)) ? -EFAULT : 0;
 160                 break;
 161
 162         case WDIOC_GETSTATUS:
 163         case WDIOC_GETBOOTSTATUS:
 164                 ret = put_user(0, (int *)arg);
 165                 break;
 166
 167         case WDIOC_KEEPALIVE:
 168                 wdt_service();
 169                 ret = 0;
 170                 break;
 171
 172         case WDIOC_GETTIMEOUT:
 173                 ret = put_user(heartbeat, (int *)arg);
 174                 break;
 175         }
 176         return ret;
 177 }
 178
 179 static int davinci_wdt_release(struct inode *inode, struct file *file)
 180 {
 181         wdt_service();
 182         clear_bit(WDT_IN_USE, &wdt_status);
 183
 184         return 0;
 185 }
 186
 187 static const struct file_operations davinci_wdt_fops = {
 188         .owner = THIS_MODULE,
 189         .llseek = no_llseek,
 190         .write = davinci_wdt_write,
 191         .unlocked_ioctl = davinci_wdt_ioctl,
 192         .open = davinci_wdt_open,
 193         .release = davinci_wdt_release,
 194 };
 195
 196 static struct miscdevice davinci_wdt_miscdev = {
 197         .minor = WATCHDOG_MINOR,
 198         .name = "watchdog",
 199         .fops = &davinci_wdt_fops,
 200 };
 201
 202 static int davinci_wdt_probe(struct platform_device *pdev)
 203 {
 204         int ret = 0;
 205         struct device *dev = &pdev->dev;
 206         struct resource  *wdt_mem;
 207
 208         wdt_clk = devm_clk_get(dev, NULL);
 209         if (WARN_ON(IS_ERR(wdt_clk)))
 210                 return PTR_ERR(wdt_clk);
 211
 212         clk_prepare_enable(wdt_clk);
 213
 214         if (heartbeat < 1 || heartbeat > MAX_HEARTBEAT)
 215                 heartbeat = DEFAULT_HEARTBEAT;
 216
 217         dev_info(dev, "heartbeat %d sec\n", heartbeat);
 218
 219         wdt_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 220         wdt_base = devm_ioremap_resource(dev, wdt_mem);
 221         if (IS_ERR(wdt_base))
 222                 return PTR_ERR(wdt_base);
 223
 224         ret = misc_register(&davinci_wdt_miscdev);
 225         if (ret < 0) {
 226                 dev_err(dev, "cannot register misc device\n");
 227         } else {
 228                 set_bit(WDT_DEVICE_INITED, &wdt_status);
 229         }
 230
 231         return ret;
 232 }
 233
 234 static int davinci_wdt_remove(struct platform_device *pdev)
 235 {
 236         misc_deregister(&davinci_wdt_miscdev);
 237         clk_disable_unprepare(wdt_clk);
 238
 239         return 0;
 240 }
 241
 242 static const struct of_device_id davinci_wdt_of_match[] = {
 243         { .compatible = "ti,davinci-wdt", },
 244         {},
 245 };
 246 MODULE_DEVICE_TABLE(of, davinci_wdt_of_match);
 247
 248 static struct platform_driver platform_wdt_driver = {
 249         .driver = {
 250                 .name = "watchdog",
 251                 .owner  = THIS_MODULE,
 252                 .of_match_table = davinci_wdt_of_match,
 253         },
 254         .probe = davinci_wdt_probe,
 255         .remove = davinci_wdt_remove,
 256 };
 257
 258 module_platform_driver(platform_wdt_driver);
 259
 260 MODULE_AUTHOR("Texas Instruments");
 261 MODULE_DESCRIPTION("DaVinci Watchdog Driver");
 262
 263 module_param(heartbeat, int, 0);
 264 MODULE_PARM_DESC(heartbeat,
 265                  "Watchdog heartbeat period in seconds from 1 to "
 266                  __MODULE_STRING(MAX_HEARTBEAT) ", default "
 267                  __MODULE_STRING(DEFAULT_HEARTBEAT));
 268
 269 MODULE_LICENSE("GPL");
 270 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 271 MODULE_ALIAS("platform:watchdog");