enable mcp2515 and the can network drivers as modules and also add a parametrizable overlay #848
Description
Maybe you want to help all the people who still rely on an externally compiled 3.12.X to make CAN-bus work out of the box by including the can drivers for the mcp2515.
What would be needed is:
.config:
CONFIG_CAN=m
CONFIG_CAN_RAW=m
CONFIG_CAN_BCM=m
CONFIG_CAN_GW=m
CONFIG_CAN_VCAN=m
CONFIG_CAN_DEV=m
CONFIG_CAN_CALC_BITTIMING=y
CONFIG_CAN_MCP251X=m
/boot/overlays/mcp2515-spi0.0.dts:
/*
* Device tree overlay for mcp2515 - can0 on spi0.0
*/
/dts-v1/;
/plugin/;
/ {
compatible = "brcm,bcm2835", "brcm,bcm2836", "brcm,bcm2708", "brcm,bcm2709";
/* disable spi-dev for spi0.0 */
fragment@0 {
target = <&spi0>;
__overlay__ {
status = "okay";
spidev@0{
status = "disabled";
};
};
};
/* the interrupt pin of the can-controller */
fragment@1 {
target = <&gpio>;
__overlay__ {
can0_pins: can0_pins {
brcm,pins = <25>;
brcm,function = <0>; /* input */
};
};
};
/* the clock/oscillator of the can-controller */
fragment@2 {
target-path = "/clocks";
__overlay__ {
/* external oscillator of mcp2515 on SPI0.0 */
can0_osc: can0_osc {
compatible = "fixed-clock";
#clock-cells = <0>;
clock-frequency = <16000000>;
};
};
};
/* the spi config of the can-controller itself binding everything together */
fragment@3 {
target = <&spi0>;
__overlay__ {
/* needed to avoid dtc warning */
#address-cells = <1>;
#size-cells = <0>;
can0: mcp2515@0 {
reg = <0>;
compatible = "microchip,mcp2515";
pinctrl-names = "default";
pinctrl-0 = <&can0_pins>;
spi-max-frequency = <10000000>;
interrupt-parent = <&gpio>;
interrupts = <25 0x2>;
clocks = <&can0_osc>;
};
};
};
__overrides__ {
oscillator = <&can0_osc>,"oscillator-frequency";
spimaxfrequency = <&can0>,"spi-max-frequency:0";
interrupt = <&can0_pins>,"brcm,pins:0",<&can0>,"interrupts:0";
};
};
This is actually a good example of how the device tree works, as it implements a lot of things that may be needed for other overlays as well (GPIOs, Interrupts, Clocks, disable a default spi device, add a new spi device instead,...)
So it may also get used as a reference/template for other device-tree overlays.
See also raspberrypi/firmware#371