regulator: pm8018-regulator: Add regulator driver for PM8018

Create a regulator driver to control all regulators on the Qualcomm
PM8018 PMIC chip.  This chip contains several different types of
regulators with a wide range of abilities and voltage ranges.

Five different regulator types are available on the PM8018.

PLDO     - PMOS low drop out linear regulator
NLDO     - NMOS low drop out linear regulator
NLDO1200 - 1.2A NMOS LDO (different control structure than other LDOs)
SMPS     - switched-mode power supply
VS       - voltage switch

The driver interfaces with the PMIC using Qualcomm's SSBI bus.
Calls to this bus are abstracted through the pm8xxx_readb/writeb API.

Signed-off-by: David Collins <collinsd@codeaurora.org>
diff --git a/drivers/regulator/Kconfig b/drivers/regulator/Kconfig
index 3ebf2aa..8eb443f 100644
--- a/drivers/regulator/Kconfig
+++ b/drivers/regulator/Kconfig
@@ -345,5 +345,14 @@
 	  chip. It is only supposed to be used when Linux on application
 	  processor is the master in control of XO buffers.
 
+config REGULATOR_PM8018
+	tristate "Qualcomm PM8018 PMIC Power regulators"
+	depends on MFD_PM8018_CORE
+	default y if MFD_PM8018_CORE
+	help
+	  This driver supports voltage regulators in the Qualcomm PM8018 PMIC
+	  chip.  The PM8018 provides several different varieties of LDO and
+	  switching regulators.  It also provides a voltage switch.
+
 endif