power: pm8xxx-ccadc: implement quick calibration

There are certain systems that wakeup every so often to do some
housekeeping work. We don't want to run a full calibration
when the system wakeups.

For such systems runs a quick calibration with just two samples.
Use the periodic_wakeup flag to indicate such a system.

CRs-Fixed: 454221
Change-Id: Ifc86414f7fab4d0921e3289d6e52b9e077a1f625
Signed-off-by: Abhijeet Dharmapurikar <adharmap@codeaurora.org>
diff --git a/include/linux/mfd/pm8xxx/ccadc.h b/include/linux/mfd/pm8xxx/ccadc.h
index 955e286..a29486f 100644
--- a/include/linux/mfd/pm8xxx/ccadc.h
+++ b/include/linux/mfd/pm8xxx/ccadc.h
@@ -1,4 +1,4 @@
-/* Copyright (c) 2010-2012, The Linux Foundation. All rights reserved.
+/* Copyright (c) 2010-2013, The Linux Foundation. All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 and
@@ -26,11 +26,15 @@
  * @ccadc_cdata:	core data for the ccadc driver containing channel info
  * @r_sense_uohm:		sense resistor value in (micro Ohms)
  * @calib_delay_ms:	how often should the adc calculate gain and offset
+ * @periodic_wakeup:	a flag to indicate that this system wakeups periodically
+ *			for calibration/other housekeeping activities. The ccadc
+ *			does a quick calibration while resuming
  */
 struct pm8xxx_ccadc_platform_data {
 	struct pm8xxx_ccadc_core_data	ccadc_cdata;
 	int				r_sense_uohm;
 	unsigned int			calib_delay_ms;
+	bool				periodic_wakeup;
 };
 
 #define CCADC_READING_RESOLUTION_N	542535