Watchdog: omap_wdt: add fine grain runtime-pm

The omap_wdt should only be in full active state when the
registers are being accessed. Otherwise the device can be
on lower power mode.

This patch is based on a patch created by Kalle Jokiniemi:
https://patchwork.kernel.org/patch/618231/
which is itself based on a patch created by Atal
Shargorodsky: http://lkml.org/lkml/2009/3/10/266.

Signed-off-by: Paul Walmsley <[e-mail]>
Signed-off-by: Kalle Jokiniemi <[e-mail]>
Tested-by: Kalle Jokiniemi <[e-mail]>
Cc: Wim Van Sebroeck <[e-mail]>
Acked-by: Wim Van Sebroeck <[e-mail]>
Acked-by: Kevin Hilman <[e-mail]>

drivers/watchdog/omap_wdt.c

···
 	u32 pre_margin = GET_WLDR_VAL(timer_margin);
 	void __iomem *base = wdev->base;
 
+	pm_runtime_get_sync(wdev->dev);
+
 	/* just count up at 32 KHz */
 	while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x04)
 		cpu_relax();
···
 	__raw_writel(pre_margin, base + OMAP_WATCHDOG_LDR);
 	while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x04)
 		cpu_relax();
+
+	pm_runtime_put_sync(wdev->dev);
 }
 
 /*
···
 	omap_wdt_ping(wdev); /* trigger loading of new timeout value */
 	omap_wdt_enable(wdev);
 
+	pm_runtime_put_sync(wdev->dev);
+
 	return nonseekable_open(inode, file);
 }
 
···
 	 *      Shut off the timer unless NOWAYOUT is defined.
 	 */
 #ifndef CONFIG_WATCHDOG_NOWAYOUT
+	pm_runtime_get_sync(wdev->dev);
 
 	omap_wdt_disable(wdev);
 
···
 
 	/* Refresh LOAD_TIME. */
 	if (len) {
+		pm_runtime_get_sync(wdev->dev);
 		spin_lock(&wdt_lock);
 		omap_wdt_ping(wdev);
 		spin_unlock(&wdt_lock);
+		pm_runtime_put_sync(wdev->dev);
 	}
 	return len;
 }
···
 			return put_user(omap_prcm_get_reset_sources(),
 					(int __user *)arg);
 	case WDIOC_KEEPALIVE:
+		pm_runtime_get_sync(wdev->dev);
 		spin_lock(&wdt_lock);
 		omap_wdt_ping(wdev);
 		spin_unlock(&wdt_lock);
+		pm_runtime_put_sync(wdev->dev);
 		return 0;
 	case WDIOC_SETTIMEOUT:
 		if (get_user(new_margin, (int __user *)arg))
 			return -EFAULT;
 		omap_wdt_adjust_timeout(new_margin);
 
+		pm_runtime_get_sync(wdev->dev);
 		spin_lock(&wdt_lock);
 		omap_wdt_disable(wdev);
 		omap_wdt_set_timeout(wdev);
···
 
 		omap_wdt_ping(wdev);
 		spin_unlock(&wdt_lock);
+		pm_runtime_put_sync(wdev->dev);
 		/* Fall */
 	case WDIOC_GETTIMEOUT:
 		return put_user(timer_margin, (int __user *)arg);
···
 {
 	struct omap_wdt_dev *wdev = platform_get_drvdata(pdev);
 
-	if (wdev->omap_wdt_users)
+	if (wdev->omap_wdt_users) {
+		pm_runtime_get_sync(wdev->dev);
 		omap_wdt_disable(wdev);
+		pm_runtime_put_sync(wdev->dev);
+	}
 }
 
 static int __devexit omap_wdt_remove(struct platform_device *pdev)
···
 {
 	struct omap_wdt_dev *wdev = platform_get_drvdata(pdev);
 
-	if (wdev->omap_wdt_users)
+	if (wdev->omap_wdt_users) {
+		pm_runtime_get_sync(wdev->dev);
 		omap_wdt_disable(wdev);
+		pm_runtime_put_sync(wdev->dev);
+	}
 
 	return 0;
 }
···
 	struct omap_wdt_dev *wdev = platform_get_drvdata(pdev);
 
 	if (wdev->omap_wdt_users) {
+		pm_runtime_get_sync(wdev->dev);
 		omap_wdt_enable(wdev);
 		omap_wdt_ping(wdev);
+		pm_runtime_put_sync(wdev->dev);
 	}
 
 	return 0;