mfd: sec-core: Prepare regulators for suspend state to reduce power-consumption

This patch use regulator_suspend_prepare() function to prepare the proper state
of regulators for suspend state to remove un-necessary leakage power-consumption.
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/Kconfig

@@ -587,6 +587,7 @@ config MFD_SEC_CORE
 	select MFD_CORE
 	select REGMAP_I2C
 	select REGMAP_IRQ
+	select REGULATOR
 	help
 	 Support for the Samsung Electronics MFD series.
 	 This driver provides common support for accessing the device,

drivers/mfd/sec-core.c

@@ -31,6 +31,7 @@
 #include <linux/mfd/samsung/s2mpu02.h>
 #include <linux/mfd/samsung/s5m8763.h>
 #include <linux/mfd/samsung/s5m8767.h>
+#include <linux/regulator/machine.h>
 #include <linux/regmap.h>
 
 static const struct mfd_cell s5m8751_devs[] = {
@@ -430,6 +431,15 @@ static int sec_pmic_suspend(struct device *dev)
 	 */
 	disable_irq(sec_pmic->irq);
 
+	switch (sec_pmic->device_type) {
+	case S2MPS14X:
+	case S2MPU02:
+		regulator_suspend_prepare(PM_SUSPEND_MEM);
+		break;
+	default:
+		break;
+	}
+
 	return 0;
 }