mfd: AXP20x: Add bindings documentation

Bindings documentation for the AXP20x driver. In this file also
sub-nodes are documented.

Signed-off-by: Carlo Caione <carlo@caione.org>
[wens@csie.org: clarify interrupt source for the axp PMIC]
[wens@csie.org: explain dcdc-workmode in detail and trim lines to 80 chars]
[wens@csie.org: make regulator supplies optional if using unregulated input]
[wens@csie.org: use cubieboard2 regulator nodes as example]
[wens@csie.org: x-powers,dcdc-workmode default changed to 'current hardware setting']
[wens@csie.org: reorganized regulator related properties into separate section.]
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

diff --git a/Documentation/devicetree/bindings/mfd/axp20x.txt b/Documentation/devicetree/bindings/mfd/axp20x.txt
new file mode 100644 (file)
index 0000000..98685f2
--- /dev/null
+++ b/Documentation/devicetree/bindings/mfd/axp20x.txt
@@ -0,0 +1,96 @@
+AXP202/AXP209 device tree bindings
+
+The axp20x family current members :
+axp202 (X-Powers)
+axp209 (X-Powers)
+
+Required properties:
+- compatible: "x-powers,axp202" or "x-powers,axp209"
+- reg: The I2C slave address for the AXP chip
+- interrupt-parent: The parent interrupt controller
+- interrupts: SoC NMI / GPIO interrupt connected to the PMIC's IRQ pin
+- interrupt-controller: axp20x has its own internal IRQs
+- #interrupt-cells: Should be set to 1
+
+Optional properties:
+- x-powers,dcdc-freq: defines the work frequency of DC-DC in KHz
+                     (range: 750-1875). Default: 1.5MHz
+- <input>-supply: a phandle to the regulator supply node. May be omitted if
+                 inputs are unregulated, such as using the IPSOUT output
+                 from the PMIC.
+
+- regulators: A node that houses a sub-node for each regulator. Regulators
+             not used but preferred to be managed by the OS should be
+             listed as well.
+             See Documentation/devicetree/bindings/regulator/regulator.txt
+             for more information on standard regulator bindings.
+
+Optional properties for DCDC regulators:
+- x-powers,dcdc-workmode: 1 for PWM mode, 0 for AUTO (PWM/PFM) mode
+                         Default: Current hardware setting
+                         The DCDC regulators work in a mixed PWM/PFM mode,
+                         using PFM under light loads and switching to PWM
+                         for heavier loads. Forcing PWM mode trades efficiency
+                         under light loads for lower output noise. This
+                         probably makes sense for HiFi audio related
+                         applications that aren't battery constrained.
+
+
+AXP202/AXP209 regulators, type, and corresponding input supply names:
+
+Regulator        Type            Supply Name             Notes
+---------        ----            -----------             -----
+DCDC2          : DC-DC buck    : vin2-supply
+DCDC3          : DC-DC buck    : vin3-supply
+LDO1           : LDO           : acin-supply           : always on
+LDO2           : LDO           : ldo24in-supply        : shared supply
+LDO3           : LDO           : ldo3in-supply
+LDO4           : LDO           : ldo24in-supply        : shared supply
+LDO5           : LDO           : ldo5in-supply
+
+Example:
+
+axp209: pmic@34 {
+       compatible = "x-powers,axp209";
+       reg = <0x34>;
+       interrupt-parent = <&nmi_intc>;
+       interrupts = <0 IRQ_TYPE_LEVEL_LOW>;
+       interrupt-controller;
+       #interrupt-cells = <1>;
+
+       regulators {
+               x-powers,dcdc-freq = <1500>;
+
+               vdd_cpu: dcdc2 {
+                       regulator-always-on;
+                       regulator-min-microvolt = <1000000>;
+                       regulator-max-microvolt = <1450000>;
+                       regulator-name = "vdd-cpu";
+               };
+
+               vdd_int_dll: dcdc3 {
+                       regulator-always-on;
+                       regulator-min-microvolt = <1000000>;
+                       regulator-max-microvolt = <1400000>;
+                       regulator-name = "vdd-int-dll";
+               };
+
+               vdd_rtc: ldo1 {
+                       regulator-always-on;
+                       regulator-min-microvolt = <1200000>;
+                       regulator-max-microvolt = <1400000>;
+                       regulator-name = "vdd-rtc";
+               };
+
+               avcc: ldo2 {
+                       regulator-always-on;
+                       regulator-min-microvolt = <2700000>;
+                       regulator-max-microvolt = <3300000>;
+                       regulator-name = "avcc";
+               };
+
+               ldo3 {
+                       /* unused but preferred to be managed by OS */
+               };
+       };
+};