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| -rwxr-xr-x | Documentation/devicetree/bindings/net/can/fsl-flexcan.txt | 61 |
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diff --git a/Documentation/devicetree/bindings/net/can/fsl-flexcan.txt b/Documentation/devicetree/bindings/net/can/fsl-flexcan.txt new file mode 100755 index 0000000..1a729f0 --- /dev/null +++ b/Documentation/devicetree/bindings/net/can/fsl-flexcan.txt @@ -0,0 +1,61 @@ +CAN Device Tree Bindings +------------------------ +2011 Freescale Semiconductor, Inc. + +fsl,flexcan-v1.0 nodes +----------------------- +In addition to the required compatible-, reg- and interrupt-properties, you can +also specify which clock source shall be used for the controller. + +CPI Clock- Can Protocol Interface Clock + This CLK_SRC bit of CTRL(control register) selects the clock source to + the CAN Protocol Interface(CPI) to be either the peripheral clock + (driven by the PLL) or the crystal oscillator clock. The selected clock + is the one fed to the prescaler to generate the Serial Clock (Sclock). + The PRESDIV field of CTRL(control register) controls a prescaler that + generates the Serial Clock (Sclock), whose period defines the + time quantum used to compose the CAN waveform. + +Can Engine Clock Source + There are two sources for CAN clock + - Platform Clock It represents the bus clock + - Oscillator Clock + + Peripheral Clock (PLL) + -------------- + | + --------- ------------- + | |CPI Clock | Prescaler | Sclock + | |---------------->| (1.. 256) |------------> + --------- ------------- + | | + -------------- ---------------------CLK_SRC + Oscillator Clock + +- fsl,flexcan-clock-source : CAN Engine Clock Source.This property selects + the peripheral clock. PLL clock is fed to the + prescaler to generate the Serial Clock (Sclock). + Valid values are "oscillator" and "platform" + "oscillator": CAN engine clock source is oscillator clock. + "platform" The CAN engine clock source is the bus clock + (platform clock). + +- fsl,flexcan-clock-divider : for the reference and system clock, an additional + clock divider can be specified. +- clock-frequency: frequency required to calculate the bitrate for FlexCAN. + +Note: + - v1.0 of flexcan-v1.0 represent the IP block version for P1010 SOC. + - P1010 does not have oscillator as the Clock Source.So the default + Clock Source is platform clock. +Examples: + + can0@1c000 { + compatible = "fsl,flexcan-v1.0"; + reg = <0x1c000 0x1000>; + interrupts = <48 0x2>; + interrupt-parent = <&mpic>; + fsl,flexcan-clock-source = "platform"; + fsl,flexcan-clock-divider = <2>; + clock-frequency = <fixed by u-boot>; + }; |