QTI 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 and multimedia cores on
chipsets like SDM845 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", "sw-reset", "hw-ctrl-addr".
 - qcom,no-status-check-on-disable: Do not poll the status bit when GDSC
			is disabled.
 - qcom,skip-disable:	Boolean flag indicating that the GDSC must not be
			physically disabled upon a software disable request.
			Instead, the GDSC will be disabled by the always-on
			processor (AOP) upon entering system sleep.  The AOP
			will also perform a special reset sequence for the GDSC
			upon resuming from system sleep.
 - 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.
 - qcom,gds-timeout:	Maximum time (in usecs) that might be taken by a GDSC
			to enable.
 - qcom,reset-aon-logic: If present, the GPU DEMET cells need to be reset while
			 enabling the GX GDSC.
 - vdd_parent-supply:	phandle to the regulator that this GDSC gates. If
			present, need to vote for a minimum operational voltage
			(LOW_SVS) on the GDSC parent regulator prior to
			configuring it. The vote is removed once the GDSC FSM
			has latched on to the new state.
 - resets: reset specifier pair consisting of phandle for the reset controller
			and reset lines used by this controller. These can be
			supplied only if we support qcom,skip-logic-collapse.
 - reset-names: reset signal name strings sorted in the same order as the resets
			property. These can be supplied only if we support
			qcom,skip-logic-collapse.
 - qcom,msm-bus,name:	Name to use for the bus client.  See [1] for details.
 - qcom,msm-bus,num-cases: Must be 2 if qcom,msm-bus,name is specified.  The
			first case corresponds to no bus request and the second
			case corresponds to a minimum bus request.  See [1] for
			details.
 - qcom,msm-bus,num-paths: Should be 1 if qcom,msm-bus,name is specified.  See
			[1] for details.
 - qcom,msm-bus,vectors-KBps: Required if qcom,msm-bus,name is specified.  See
			[1] for an explanation of the data format.
 - mboxes:		Mailbox tuple containing QMP mailbox phandle and channel
			identifier.  If this is specified, then a QMP message
			should be sent to enable the GDSC instead of setting
			SW_COLLAPSE=0.

[1]: Documentation/devicetree/bindings/arm/msm/msm_bus.txt

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";
	};