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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,retain-regs: Presence denotes a hardware requirement to enable the
usage of retention registers which maintain their state
after the GDSC is disabled and re-enabled.
- 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,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.
- qcom,skip-disable-before-sw-enable : Presence denotes a hardware requirement
to leave the GDSC on that has been
enabled by an entity external to HLOS.
- qcom,no-config-gdscr: Presence denotes HW only supports a single register
per GDSC.
[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";
};
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