//将一个IO地址空间映射到内核的虚拟地址空间上去，便于访问
wdt_base = ioremap(res->start, size);
if (wdt_base == NULL) {
dev_err(dev, "failed to ioremap() region\n");
ret = -EINVAL;
goto err_req;
}
DBG("probe: mapped wdt_base=%p\n", wdt_base);
/* get the memory region for the watchdog timer -- flags is IORESOURCE_IRQ */
wdt_irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
if (wdt_irq == NULL) {
dev_err(dev, "no irq resource specified\n");
ret = -ENOENT;
goto err_map;
}
//注册中断服务函数s3c2410wdt_irq()
ret = request_irq(wdt_irq->start, s3c2410wdt_irq, 0, pdev->name, pdev);
if (ret != 0) {
dev_err(dev, "failed to install irq (%d)\n", ret);
goto err_map;
}
//从平台时钟队列中获取clk
wdt_clock = clk_get(&pdev->dev, "watchdog");
if (IS_ERR(wdt_clock)) {
dev_err(dev, "failed to find watchdog clock source\n");
ret = PTR_ERR(wdt_clock);
goto err_irq;
}
//inform the system when the clock source should be running
clk_enable(wdt_clock);
/* see if we can actually set the requested timer margin, and if
* not, try the default value */
if (s3c2410wdt_set_heartbeat(tmr_margin)) {
started = s3c2410wdt_set_heartbeat(
CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);
if (started == 0)
dev_info(dev,
"tmr_margin value out of range, default %d used\n",
CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);
else
dev_info(dev, "default timer value is out of range, "
"cannot start\n");
}
ret = misc_register(&s3c2410wdt_miscdev);
if (ret) {
dev_err(dev, "cannot register miscdev on minor=%d (%d)\n",
WATCHDOG_MINOR, ret);
goto err_clk;
}
if (tmr_atboot && started == 0) {
dev_info(dev, "starting watchdog timer\n");
s3c2410wdt_start();
} else if (!tmr_atboot) {
/* if we're not enabling the watchdog, then ensure it is
* disabled if it has been left running from the bootloader
* or other source */
s3c2410wdt_stop();
}
/* print out a statement of readiness */
wtcon = readl(wdt_base + S3C2410_WTCON);
dev_info(dev, "watchdog %sactive, reset %sabled, irq %sabled\n",
(wtcon & S3C2410_WTCON_ENABLE) ? "" : "in",
(wtcon & S3C2410_WTCON_RSTEN) ? "" : "dis",
(wtcon & S3C2410_WTCON_INTEN) ? "" : "en");
return 0;
err_clk:
clk_disable(wdt_clock);
clk_put(wdt_clock);
err_irq:
free_irq(wdt_irq->start, pdev);
err_map:
iounmap(wdt_base);
err_req:
release_resource(wdt_mem);
kfree(wdt_mem);
return ret;
}
static int __devexit s3c2410wdt_remove(struct platform_device *dev)
{
release_resource(wdt_mem);
kfree(wdt_mem);
wdt_mem = NULL;
free_irq(wdt_irq->start, dev);
wdt_irq = NULL;
clk_disable(wdt_clock);
clk_put(wdt_clock);
wdt_clock = NULL;
iounmap(wdt_base);
misc_deregister(&s3c2410wdt_miscdev);
return 0;
}
static void s3c2410wdt_shutdown(struct platform_device *dev)
{
s3c2410wdt_stop();
}
#ifdef CONFIG_PM
static unsigned long wtcon_save;
static unsigned long wtdat_save;
static int s3c2410wdt_suspend(struct platform_device *dev, pm_message_t state)
{
/* Save watchdog state, and turn it off. */
wtcon_save = readl(wdt_base + S3C2410_WTCON);
wtdat_save = readl(wdt_base + S3C2410_WTDAT);
/* Note that WTCNT doesn't need to be saved. */
s3c2410wdt_stop();
return 0;
}
static int s3c2410wdt_resume(struct platform_device *dev)
{
/* Restore watchdog state. */
writel(wtdat_save, wdt_base + S3C2410_WTDAT);
writel(wtdat_save, wdt_base + S3C2410_WTCNT); /* Reset count */
writel(wtcon_save, wdt_base + S3C2410_WTCON);
printk(KERN_INFO PFX "watchdog %sabled\n",
(wtcon_save & S3C2410_WTCON_ENABLE) ? "en" : "dis");
return 0;
}
#else
#define s3c2410wdt_suspend NULL
#define s3c2410wdt_resume NULL
#endif /* CONFIG_PM */