详解linux看门狗驱动编写

drivers/watchdog 

config HAVE_S3C2410_WATCHDOG 
  bool 
  help 
   This will include watchdog timer support for Samsung SoCs. If 
   you want to include watchdog support for any machine, kindly 
   select this in the respective mach-XXXX/Kconfig file. 
 
config S3C2410_WATCHDOG 
  tristate "S3C2410 Watchdog" 
  depends on HAVE_S3C2410_WATCHDOG || COMPILE_TEST 
  select WATCHDOG_CORE 
  select MFD_SYSCON if ARCH_EXYNOS 
  help 
   Watchdog timer block in the Samsung SoCs. This will reboot 
   the system when the timer expires with the watchdog enabled. 
 
   The driver is limited by the speed of the system's PCLK 
   signal, so with reasonably fast systems (PCLK around 50-66MHz) 
   then watchdog intervals of over approximately 20seconds are 
   unavailable. 
 
   The driver can be built as a module by choosing M, and will 
   be called s3c2410_wdt 

obj-$(CONFIG_S3C2410_WATCHDOG) += s3c2410_wdt.o 

static SIMPLE_DEV_PM_OPS(s3c2410wdt_pm_ops, s3c2410wdt_suspend, 
      s3c2410wdt_resume); 
 
static struct platform_driver s3c2410wdt_driver = { 
  .probe   = s3c2410wdt_probe, 
  .remove   = s3c2410wdt_remove, 
  .shutdown  = s3c2410wdt_shutdown, 
  .id_table  = s3c2410_wdt_ids, 
  .driver   = { 
    .name  = "s3c2410-wdt", 
    .pm = &s3c2410wdt_pm_ops, 
    .of_match_table = of_match_ptr(s3c2410_wdt_match), 
  }, 
}; 
 
module_platform_driver(s3c2410wdt_driver); 

ret = watchdog_register_device(&wdt->wdt_device); 
if (ret) { 
  dev_err(dev, "cannot register watchdog (%d)\n", ret); 
  goto err_cpufreq; 
} 

static const struct watchdog_info s3c2410_wdt_ident = { 
  .optiOns=   OPTIONS, 
  .firmware_version = 0, 
  .identity     = "S3C2410 Watchdog", 
}; 
 
static const struct watchdog_ops s3c2410wdt_ops = { 
  .owner = THIS_MODULE, 
  .start = s3c2410wdt_start, 
  .stop = s3c2410wdt_stop, 
  .ping = s3c2410wdt_keepalive, 
  .set_timeout = s3c2410wdt_set_heartbeat, 
  .restart = s3c2410wdt_restart, 
}; 
 
static const struct watchdog_device s3c2410_wdd = { 
  .info = &s3c2410_wdt_ident, 
  .ops = &s3c2410wdt_ops, 
  .timeout = S3C2410_WATCHDOG_DEFAULT_TIME, 
}; 

ret = devm_request_irq(dev, wdt_irq->start, s3c2410wdt_irq, 0, 
      pdev->name, pdev); 
if (ret != 0) { 
  dev_err(dev, "failed to install irq (%d)\n", ret); 
  goto err_cpufreq; 
} 

static int s3c2410wdt_restart(struct watchdog_device *wdd, unsigned long action, 
         void *data) 
{ 
  struct s3c2410_wdt *wdt = watchdog_get_drvdata(wdd); 
  void __iomem *wdt_base = wdt->reg_base; 
 
  /* disable watchdog, to be safe */ 
  writel(0, wdt_base + S3C2410_WTCON); 
 
  /* put initial values into count and data */ 
  writel(0x80, wdt_base + S3C2410_WTCNT); 
  writel(0x80, wdt_base + S3C2410_WTDAT); 
 
  /* set the watchdog to go and reset... */ 
  writel(S3C2410_WTCON_ENABLE | S3C2410_WTCON_DIV16 | 
    S3C2410_WTCON_RSTEN | S3C2410_WTCON_PRESCALE(0x20), 
    wdt_base + S3C2410_WTCON); 
 
  /* wait for reset to assert... */ 
  mdelay(500); 
 
  return 0; 
}