clk: msm: Add documentation for gdsc regulator driver

This is a snapshot of gdsc-regulator documentation as of
msm-3.18 commit:

e70ad0cd5efdd9dc91a77dcdac31d6132e1315c1 (Promotion of
kernel.lnx.3.18-151201.)

Signed-off-by: Devesh Jhunjhunwala <deveshj@codeaurora.org>

1 files changed, 57 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/regulator/gdsc-regulator.txt b/Documentation/devicetree/bindings/regulator/gdsc-regulator.txt
new file mode 100644
index 000000000000..b4ef2566727b
--- /dev/null
+++ b/Documentation/devicetree/bindings/regulator/gdsc-regulator.txt
@@ -0,0 +1,57 @@
+Qualcomm Global Distributed Switch Controller (GDSC) Regulator Driver
+
+The GDSC driver, implemented under the regulator framework, is responsible for
+safely collapsing and restoring power to peripheral cores on chipsets like
+msm8974 for power savings.
+
+Required properties:
+ - compatible:      Must be "qcom,gdsc"
+ - regulator-name:  A string used as a descriptive name for regulator outputs
+ - reg:             The address of the GDSCR register
+
+Optional properties:
+ - parent-supply:   phandle to the parent supply/regulator node
+ - clock-names:     List of string names for core clocks
+ - qcom,retain-mem:  Presence denotes a hardware requirement to leave the
+		     forced core memory retention signals in the core's clock
+		     branch control registers asserted.
+ - qcom,retain-periph: Presence denotes a hardware requirement to leave the
+		     forced periph memory retention signal in the core's clock
+		     branch control registers asserted.
+ - qcom,skip-logic-collapse: Presence denotes a requirement to leave power to
+                             the core's logic enabled.
+ - qcom,support-hw-trigger: Presence denotes a hardware feature to switch
+			    on/off this regulator based on internal HW signals
+			    to save more power.
+ - qcom,enable-root-clk: Presence denotes that the clocks in the "clocks"
+			property are required to be enabled before gdsc is
+			turned on and disabled before turning off gdsc. This
+			will be used in subsystems where reset is synchronous
+			and root clk is active without sw being aware of its
+			state. The clock-name which denotes the root clock
+			should be named as "core_root_clk".
+ - qcom,force-enable-root-clk: If set, denotes that the root clock should be
+			force enabled before turning on the GDSC and then be
+			immediately force disabled. Likewise for GDSC disable.
+			This is used in cases where the core root clock needs
+			to be force-enabled prior to turning on the core. The
+			clock-name which denotes the root clock should be
+			"core_root_clk".
+ - qcom,clk-dis-wait-val: Input value for CLK_DIS_WAIT controls state transition
+			 delay after halting clock in the collapsible core.
+ - reg-names:		Names of the bases for the above "reg" registers.
+			Ex. "base", "domain_addr".
+ - qcom,no-status-check-on-disable: Do not poll the status bit when GDSC
+			is disabled.
+ - qcom,disallow-clear: Presence denotes the periph & core memory will not be
+			cleared, unless the required subsystem does not invoke
+			the api which will allow clearing the bits.
+
+Example:
+	gdsc_oxili_gx: qcom,gdsc@fd8c4024 {
+		compatible = "qcom,gdsc";
+		regulator-name = "gdsc_oxili_gx";
+		parent-supply = <&pm8841_s4>;
+		reg = <0xfd8c4024 0x4>;
+		clock-names = "core_clk";
+	};