mfd: Add MAX8907 core driver

The MAX8907 is an I2C-based power-management IC containing voltage
regulators, a reset controller, a real-time clock, and a touch-screen
controller.

The original driver was written by:
* Gyungoh Yoo <jack.yoo@maxim-ic.com>

Various fixes and enhancements by:
* Jin Park <jinyoungp@nvidia.com>
* Tom Cherry <tcherry@nvidia.com>
* Prashant Gaikwad <pgaikwad@nvidia.com>
* Dan Willemsen <dwillemsen@nvidia.com>
* Laxman Dewangan <ldewangan@nvidia.com>

During upstreaming, I (swarren):
* Converted to regmap.
* Converted to regmap-irq.
* Allowed probing from device tree.
* Renamed from max8907c->max8907, since the driver covers at least the
  C and B revisions.
* General cleanup.

Signed-off-by: Gyungoh Yoo <jack.yoo@maxim-ic.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Mark Brown <broonie@opensource.wolfsonmicro.com> #v3
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

Documentation/devicetree/bindings/regulator/max8907.txt

@@ -0,0 +1,71 @@
+MAX8907 regulator
+
+Required properties:
+- compatible: "maxim,max8907"
+- reg: I2C slave address
+- interrupts: The interrupt output of the controller
+- mbatt-supply: The input supply for MBATT, BBAT, SDBY, VRTC.
+- in-v1-supply: The input supply for SD1.
+- in-v2-supply: The input supply for SD2.
+- in-v3-supply: The input supply for SD3.
+- in1-supply: The input supply for LDO1.
+...
+- in20-supply: The input supply for LDO20.
+- regulators: A node that houses a sub-node for each regulator within the
+  device. Each sub-node is identified using the regulator-compatible
+  property, with valid values listed below. The content of each sub-node
+  is defined by the standard binding for regulators; see regulator.txt.
+
+Valid regulator-compatible values are:
+
+  sd1, sd2, sd3, ldo1, ldo2, ldo3, ldo4, ldo5, ldo6, ldo7, ldo8, ldo9, ldo10,
+  ldo11, ldo12, ldo13, ldo14, ldo15, ldo16, ldo17, ldo18, ldo19, ldo20, out5v,
+  out33v, bbat, sdby, vrtc.
+
+Example:
+
+		max8907@3c {
+			compatible = "maxim,max8907";
+			reg = <0x3c>;
+			interrupts = <0 86 0x4>;
+
+			mbatt-supply = <&some_reg>;
+			in-v1-supply = <&mbatt_reg>;
+			...
+			in1-supply = <&mbatt_reg>;
+			...
+
+			regulators {
+				#address-cells = <1>;
+				#size-cells = <0>;
+
+				mbatt_reg: regulator@0 {
+					reg = <0>;
+					regulator-compatible = "mbatt";
+					regulator-name = "vbat_pmu";
+					regulator-min-microvolt = <5000000>;
+					regulator-max-microvolt = <5000000>;
+					regulator-always-on;
+				};
+
+				regulator@1 {
+					reg = <1>;
+					regulator-compatible = "sd1";
+					regulator-name = "nvvdd_sv1,vdd_cpu_pmu";
+					regulator-min-microvolt = <1000000>;
+					regulator-max-microvolt = <1000000>;
+					regulator-always-on;
+				};
+
+				regulator@2 {
+					reg = <2>;
+					regulator-compatible = "sd2";
+					regulator-name = "nvvdd_sv2,vdd_core";
+					regulator-min-microvolt = <1200000>;
+					regulator-max-microvolt = <1200000>;
+					regulator-always-on;
+				};
+...
+			};
+		};
+	};

drivers/mfd/Kconfig

@@ -476,6 +476,18 @@ config MFD_MAX77693
 	  additional drivers must be enabled in order to use the functionality
 	  of the device.
 
+config MFD_MAX8907
+	tristate "Maxim Semiconductor MAX8907 PMIC Support"
+	select MFD_CORE
+	depends on I2C=y && GENERIC_HARDIRQS
+	select REGMAP_I2C
+	select REGMAP_IRQ
+	help
+	  Say yes here to support for Maxim Semiconductor MAX8907. This is
+	  a Power Management IC. This driver provides common support for
+	  accessing the device; additional drivers must be enabled in order
+	  to use the functionality of the device.
+
 config MFD_MAX8925
 	bool "Maxim Semiconductor MAX8925 PMIC Support"
 	depends on I2C=y && GENERIC_HARDIRQS

drivers/mfd/Makefile

@@ -92,6 +92,7 @@ obj-$(CONFIG_MFD_DA9052_I2C)	+= da9052-i2c.o
 
 obj-$(CONFIG_MFD_MAX77686)	+= max77686.o max77686-irq.o
 obj-$(CONFIG_MFD_MAX77693)	+= max77693.o max77693-irq.o
+obj-$(CONFIG_MFD_MAX8907)	+= max8907.o
 max8925-objs			:= max8925-core.o max8925-i2c.o
 obj-$(CONFIG_MFD_MAX8925)	+= max8925.o
 obj-$(CONFIG_MFD_MAX8997)	+= max8997.o max8997-irq.o