rtc, x86/mrst/vrtc: Fix boot crash in rtc_read_alarm()

Commit f44f7f96 ("RTC: Initialize kernel state from RTC") caused a
boot regression on the MRST platform.

The reason is that rtc_device_register() calls rtc_read_alarm() after
that change, which function does not have all driver data set up yet.

The rtc-mrst driver needs to call dev_set_drvdata() before rtc_device_register()
gets called.
Signed-off-by: NFeng Tang <feng.tang@intel.com>
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Acked-by: NJohn Stultz <john.stultz@linaro.org>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1302140384-27571-1-git-send-email-feng.tang@intel.comSigned-off-by: NIngo Molnar <mingo@elte.hu>

drivers/rtc/rtc-mrst.c

@@ -342,6 +342,8 @@ vrtc_mrst_do_probe(struct device *dev, struct resource *iomem, int rtc_irq)
 
 	mrst_rtc.irq = rtc_irq;
 	mrst_rtc.iomem = iomem;
+	mrst_rtc.dev = dev;
+	dev_set_drvdata(dev, &mrst_rtc);
 
 	mrst_rtc.rtc = rtc_device_register(driver_name, dev,
 				&mrst_rtc_ops, THIS_MODULE);
@@ -350,8 +352,6 @@ vrtc_mrst_do_probe(struct device *dev, struct resource *iomem, int rtc_irq)
 		goto cleanup0;
 	}
 
-	mrst_rtc.dev = dev;
-	dev_set_drvdata(dev, &mrst_rtc);
 	rename_region(iomem, dev_name(&mrst_rtc.rtc->dev));
 
 	spin_lock_irq(&rtc_lock);
@@ -376,9 +376,10 @@ vrtc_mrst_do_probe(struct device *dev, struct resource *iomem, int rtc_irq)
 	return 0;
 
 cleanup1:
-	mrst_rtc.dev = NULL;
 	rtc_device_unregister(mrst_rtc.rtc);
 cleanup0:
+	dev_set_drvdata(dev, NULL);
+	mrst_rtc.dev = NULL;
 	release_region(iomem->start, iomem->end + 1 - iomem->start);
 	dev_err(dev, "rtc-mrst: unable to initialise\n");
 	return retval;