dt-bindings: clock: tegra124-dfll: Update DFLL binding for PWM regulator

Add new properties to configure the DFLL PWM regulator support.

Cc: [e-mail]
Signed-off-by: Peter De Schrijver <[e-mail]>
Signed-off-by: Joseph Lo <[e-mail]>
Acked-by: Jon Hunter <[e-mail]>
Reviewed-by: Rob Herring <[e-mail]>
Signed-off-by: Thierry Reding <[e-mail]>

Documentation/devicetree/bindings/clock/nvidia,tegra124-dfll.txt

···
 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.
-Currently only the I2C mode is supported by these bindings.
 
 Required properties:
 - compatible : should be "nvidia,tegra124-dfll"
···
 Optional properties for the control loop parameters:
 - nvidia,cg-scale: Boolean value, see the field DFLL_PARAMS_CG_SCALE in the TRM.
 
+Optional properties for mode selection:
+- nvidia,pwm-to-pmic: Use PWM to control regulator rather then I2C.
+
 Required properties for I2C mode:
 - nvidia,i2c-fs-rate: I2C transfer rate, if using full speed mode.
 
-Example:
+Required properties for PWM mode:
+- nvidia,pwm-period-nanoseconds: period of PWM square wave in nanoseconds.
+- nvidia,pwm-tristate-microvolts: Regulator voltage in micro volts when PWM
+  control is disabled and the PWM output is tristated. Note that this voltage is
+  configured in hardware, typically via a resistor divider.
+- nvidia,pwm-min-microvolts: Regulator voltage in micro volts when PWM control
+  is enabled and PWM output is low. Hence, this is the minimum output voltage
+  that the regulator supports when PWM control is enabled.
+- nvidia,pwm-voltage-step-microvolts: Voltage increase in micro volts
+  corresponding to a 1/33th increase in duty cycle. Eg the voltage for 2/33th
+  duty cycle would be: nvidia,pwm-min-microvolts +
+  nvidia,pwm-voltage-step-microvolts * 2.
+- pinctrl-0: I/O pad configuration when PWM control is enabled.
+- pinctrl-1: I/O pad configuration when PWM control is disabled.
+- pinctrl-names: must include the following entries:
+  - dvfs_pwm_enable: I/O pad configuration when PWM control is enabled.
+  - dvfs_pwm_disable: I/O pad configuration when PWM control is disabled.
+
+Example for I2C:
 
 clock@70110000 {
         compatible = "nvidia,tegra124-dfll";
···
         nvidia,cg = <2>;
 
         nvidia,i2c-fs-rate = <400000>;
+};
+
+Example for PWM:
+
+clock@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 TEGRA210_CLK_DFLL_SOC>,
+	         <&tegra_car TEGRA210_CLK_DFLL_REF>,
+		 <&tegra_car TEGRA124_CLK_I2C5>;;
+	clock-names = "soc", "ref", "i2c";
+	resets = <&tegra_car TEGRA124_RST_DFLL_DVCO>;
+	reset-names = "dvco";
+	#clock-cells = <0>;
+	clock-output-names = "dfllCPU_out";
+
+	nvidia,sample-rate = <25000>;
+	nvidia,droop-ctrl = <0x00000f00>;
+	nvidia,force-mode = <1>;
+	nvidia,cf = <6>;
+	nvidia,ci = <0>;
+	nvidia,cg = <2>;
+
+	nvidia,pwm-min-microvolts = <708000>; /* 708mV */
+	nvidia,pwm-period-nanoseconds = <2500>; /* 2.5us */
+	nvidia,pwm-to-pmic;
+	nvidia,pwm-tristate-microvolts = <1000000>;
+	nvidia,pwm-voltage-step-microvolts = <19200>; /* 19.2mV */
+
+	pinctrl-names = "dvfs_pwm_enable", "dvfs_pwm_disable";
+	pinctrl-0 = <&dvfs_pwm_active_state>;
+	pinctrl-1 = <&dvfs_pwm_inactive_state>;
+};
+
+/* pinmux nodes added for completeness. Binding doc can be found in:
+ * Documentation/devicetree/bindings/pinctrl/nvidia,tegra210-pinmux.txt
+ */
+
+pinmux: pinmux@700008d4 {
+	dvfs_pwm_active_state: dvfs_pwm_active {
+		dvfs_pwm_pbb1 {
+			nvidia,pins = "dvfs_pwm_pbb1";
+			nvidia,tristate = <TEGRA_PIN_DISABLE>;
+		};
+	};
+	dvfs_pwm_inactive_state: dvfs_pwm_inactive {
+		dvfs_pwm_pbb1 {
+			nvidia,pins = "dvfs_pwm_pbb1";
+			nvidia,tristate = <TEGRA_PIN_ENABLE>;
+		};
+	};
 };