FreeBSD/Linux Kernel Cross Reference
sys/contrib/device-tree/Bindings/clock/nvidia,tegra124-car.txt

     NVIDIA Tegra124 and Tegra132 Clock And Reset Controller
     
     This binding uses the common clock binding:
     Documentation/devicetree/bindings/clock/clock-bindings.txt
     
     The CAR (Clock And Reset) Controller on Tegra is the HW module responsible
     for muxing and gating Tegra's clocks, and setting their rates.
     
     Required properties :
    - compatible : Should be "nvidia,tegra124-car" or "nvidia,tegra132-car"
    - reg : Should contain CAR registers location and length
    - clocks : Should contain phandle and clock specifiers for two clocks:
      the 32 KHz "32k_in", and the board-specific oscillator "osc".
    - #clock-cells : Should be 1.
      In clock consumers, this cell represents the clock ID exposed by the
      CAR. The assignments may be found in the header files
      <dt-bindings/clock/tegra124-car-common.h> (which covers IDs common
      to Tegra124 and Tegra132) and <dt-bindings/clock/tegra124-car.h>
      (for Tegra124-specific clocks).
    - #reset-cells : Should be 1.
      In clock consumers, this cell represents the bit number in the CAR's
      array of CLK_RST_CONTROLLER_RST_DEVICES_* registers.
    - nvidia,external-memory-controller : phandle of the EMC driver.
    
    The node should contain a "emc-timings" subnode for each supported RAM type (see
    field RAM_CODE in register PMC_STRAPPING_OPT_A).
    
    Required properties for "emc-timings" nodes :
    - nvidia,ram-code : Should contain the value of RAM_CODE this timing set
      is used for.
    
    Each "emc-timings" node should contain a "timing" subnode for every supported
    EMC clock rate.
    
    Required properties for "timing" nodes :
    - clock-frequency : Should contain the memory clock rate to which this timing
    relates.
    - nvidia,parent-clock-frequency : Should contain the rate at which the current
    parent of the EMC clock should be running at this timing.
    - 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:
      - emc-parent : the clock that should be the parent of the EMC clock at this
    timing.
    
    Example SoC include file:
    
    / {
            tegra_car: clock@60006000 {
                    compatible = "nvidia,tegra124-car";
                    reg = <0x60006000 0x1000>;
                    #clock-cells = <1>;
                    #reset-cells = <1>;
                    nvidia,external-memory-controller = <&emc>;
            };
    
            usb@c5004000 {
                    clocks = <&tegra_car TEGRA124_CLK_USB2>;
            };
    };
    
    Example board file:
    
    / {
            clocks {
                    compatible = "simple-bus";
                    #address-cells = <1>;
                    #size-cells = <0>;
    
                    osc: clock@0 {
                            compatible = "fixed-clock";
                            reg = <0>;
                            #clock-cells = <0>;
                            clock-frequency = <112400000>;
                    };
    
                    clk_32k: clock@1 {
                            compatible = "fixed-clock";
                            reg = <1>;
                            #clock-cells = <0>;
                            clock-frequency = <32768>;
                    };
            };
    
            &tegra_car {
                    clocks = <&clk_32k> <&osc>;
            };
    
            clock@60006000 {
                    emc-timings-3 {
                            nvidia,ram-code = <3>;
    
                            timing-12750000 {
                                    clock-frequency = <12750000>;
                                    nvidia,parent-clock-frequency = <408000000>;
                                    clocks = <&tegra_car TEGRA124_CLK_PLL_P>;
                                    clock-names = "emc-parent";
                            };
                            timing-20400000 {
                                   clock-frequency = <20400000>;
                                   nvidia,parent-clock-frequency = <408000000>;
                                   clocks = <&tegra_car TEGRA124_CLK_PLL_P>;
                                   clock-names = "emc-parent";
                           };
                   };
           };
   };

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