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NVIDIA Tegra124 DFLL FCPU clocksource
This binding uses the common clock binding:
Documentation/devicetree/bindings/clock/clock-bindings.txt
The DFLL IP block on Tegra is a root clocksource designed for clocking
the fast CPU cluster. It consists of a free-running voltage controlled
oscillator connected to the CPU voltage rail (VDD_CPU), and a closed loop
control module that will automatically adjust the VDD_CPU voltage by
communicating with an off-chip PMIC either via an I2C bus or via PWM signals.
Required properties:
- compatible : should be "nvidia,tegra124-dfll-fcpu"
- reg : Defines the following set of registers, in the order listed:
- registers for the DFLL control logic.
- registers for the I2C output logic.
- registers for the integrated I2C master controller.
- look-up table RAM for voltage register values.
- interrupts: Should contain the DFLL block interrupt.
- clocks: Must contain an entry for each entry in clock-names.
See ../clocks/clock-bindings.txt for details.
- clock-names: Must include the following entries:
- soc: Clock source for the DFLL control logic.
- ref: The closed loop reference clock
- i2c: Clock source for the integrated I2C master.
- #clock-cells: Must be 0.
- clock-output-names: Name of the clock output.
- vdd-cpu-supply: Regulator for the CPU voltage rail that the DFLL
hardware will start controlling.
Required properties for the control loop parameters:
- nvidia,sample-rate: Sample rate of the DFLL control loop.
- nvidia,droop-ctrl: See the register CL_DVFS_DROOP_CTRL in the TRM.
- nvidia,force-mode: See the field DFLL_PARAMS_FORCE_MODE in the TRM.
- nvidia,cf: Numeric value, see the field DFLL_PARAMS_CF_PARAM in the TRM.
- nvidia,ci: Numeric value, see the field DFLL_PARAMS_CI_PARAM in the TRM.
- nvidia,cg: Numeric value, see the field DFLL_PARAMS_CG_PARAM in the TRM.
- nvidia,cg-scale: Boolean value, see the field DFLL_PARAMS_CG_SCALE in the TRM.
Required properties for I2C mode:
- nvidia,i2c-fs-rate: I2C transfer rate, if using FS mode.
Example:
dfll@0,70110000 {
compatible = "nvidia,tegra124-dfll";
reg = <0 0x70110000 0 0x100>, /* DFLL control */
<0 0x70110000 0 0x100>, /* I2C output control */
<0 0x70110100 0 0x100>, /* Integrated I2C controller */
<0 0x70110200 0 0x100>; /* Look-up table RAM */
interrupts = <GIC_SPI 62 IRQ_TYPE_LEVEL_HIGH>;
clocks = <&tegra_car TEGRA124_CLK_DFLL_SOC>,
<&tegra_car TEGRA124_CLK_DFLL_REF>,
<&tegra_car TEGRA124_CLK_I2C5>;
clock-names = "soc", "ref", "i2c";
#clock-cells = <0>;
clock-output-names = "dfllCPU_out";
vdd-cpu-supply = <&vdd_cpu>;
status = "okay";
nvidia,sample-rate = <12500>;
nvidia,droop-ctrl = <0x00000f00>;
nvidia,force-mode = <1>;
nvidia,cf = <10>;
nvidia,ci = <0>;
nvidia,cg = <2>;
nvidia,i2c-fs-rate = <400000>;
};
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