I'm trying to connect 6 mcp2515 over spi0. I have adapted an SPI overlay to add the neccesary chip select lines. My new SPI overlay looks like this:
{
compatible = "brcm,bcm2835", "brcm,bcm2836", "brcm,bcm2708", "brcm,bcm2709";
fragment@0 {
target = <&spi0>;
frag0: __overlay__ {
#address-cells = <1>;
#size-cells = <0>;
pinctrl-0 = <&spi0_pins &spi0_cs_pins>;
status = "okay";
cs-gpios = <&gpio 8 1>, <&gpio 7 1>, <&gpio 22 1>, <&gpio 23 1>, <&gpio 24 1>, <&gpio 25 1>;
spidev@0{
compatible = "spidev";
reg = <0>; /* CE0 */
#address-cells = <1>;
#size-cells = <0>;
spi-max-frequency = <500000>;
};
spidev@1{
compatible = "spidev";
reg = <1>; /* CE1 */
#address-cells = <1>;
#size-cells = <0>;
spi-max-frequency = <500000>;
};
spidev@2{
compatible = "spidev";
reg = <2>; /* CE2 */
#address-cells = <1>;
#size-cells = <0>;
spi-max-frequency = <500000>;
};
spidev@3{
compatible = "spidev";
reg = <3>; /* CE3 */
#address-cells = <1>;
#size-cells = <0>;
spi-max-frequency = <500000>;
};
spidev@4{
compatible = "spidev";
reg = <4>; /* CE4 */
#address-cells = <1>;
#size-cells = <0>;
spi-max-frequency = <500000>;
};
spidev@5{
compatible = "spidev";
reg = <5>; /* CE5 */
#address-cells = <1>;
#size-cells = <0>;
spi-max-frequency = <500000>;
};
};
};
fragment@1 {
target = <&gpio>;
__overlay__ {
spi0_cs_pins: spi0_cs_pins {
brcm,pins = <7 8 22 23 24 25>;
brcm,function = <1>; /* out */
};
};
};
With this SPI overlay i have the 6 spi's in /sys/bus/spi/devices/
spi0.0 spi0.1 spi0.2 spi0.3 spi0.4 spi0.5
I have also made new overlays for the mcp2515 (can0 to can5) in order to bind them with the new chip select lines of spi0.
My /boot/config.txt looks like this:
dtoverlay=spi-gpio-cs-new
dtoverlay=mcp2515-can0,oscillator=8000000,interrupt=5
dtoverlay=mcp2515-can4,oscillator=8000000,interrupt=26
dtoverlay=mcp2515-can5,oscillator=8000000,interrupt=27
dmesg | grep mcp
[ 7.870207] mcp251x spi0.5 can0: MCP2515 successfully initialized.
[ 7.892886] mcp251x spi0.4 can1: MCP2515 successfully initialized.
[ 7.908725] mcp251x spi0.0 can2: MCP2515 successfully initialized.
ifconfig
can0: flags=193<UP,RUNNING,NOARP> mtu 16
unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 txqueuelen 10 (UNSPEC)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
can1: flags=193<UP,RUNNING,NOARP> mtu 16
unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 txqueuelen 10 (UNSPEC)
RX packets 36 bytes 180 (180.0 B)
RX errors 0 dropped 36 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
can2: flags=193<UP,RUNNING,NOARP> mtu 16
unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 txqueuelen 10 (UNSPEC)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
I only have 3 mcp2515 boards at my disposal for the moment. I have modified them regarding voltage supply to the CAN transceiver(5V) and can controller(3V) in order no to damage the Raspberry Pi GPIO's, the boards have been individually tested and I was able to send/receive CAN frames with them. They are connected to the Raspberry like this
Out of these 3 interfaces only can1 (spi0.4) is working! Using candump I can see can frames on the network.
My question is why can0 and can2 are muted when trying to send or receive CAN messages (candump and cansend)?
Kernel interrupt table
CPU0 CPU1 CPU2 CPU3
17: 217 0 0 0 ARMCTRL-level 1 Edge 3f00b880.mailbox
18: 47 0 0 0 ARMCTRL-level 2 Edge VCHIQ doorbell
40: 0 0 0 0 ARMCTRL-level 48 Edge bcm2708_fb DMA
42: 352 0 0 0 ARMCTRL-level 50 Edge DMA IRQ
44: 3062 0 0 0 ARMCTRL-level 52 Edge DMA IRQ
45: 0 0 0 0 ARMCTRL-level 53 Edge DMA IRQ
48: 0 0 0 0 ARMCTRL-level 56 Edge DMA IRQ
56: 14104 0 0 0 ARMCTRL-level 64 Edge dwc_otg, dwc_otg_pcd, dwc_otg_hcd:usb1
78: 0 0 0 0 ARMCTRL-level 86 Edge 3f204000.spi
80: 158 0 0 0 ARMCTRL-level 88 Edge mmc0
81: 7450 0 0 0 ARMCTRL-level 89 Edge uart-pl011
86: 4207 0 0 0 ARMCTRL-level 94 Edge mmc1
161: 0 0 0 0 bcm2836-timer 0 Edge arch_timer
162: 1813 1900 2264 1528 bcm2836-timer 1 Edge arch_timer
165: 0 0 0 0 bcm2836-pmu 9 Edge arm-pmu
166: 0 0 0 0 lan78xx-irqs 17 Edge usb-001:004:01
167: 0 0 0 0 pinctrl-bcm2835 26 Edge spi0.5
168: 6 0 0 0 pinctrl-bcm2835 27 Edge spi0.4
169: 0 0 0 0 pinctrl-bcm2835 5 Level spi0.0
FIQ: usb_fiq
IPI0: 0 0 0 0 CPU wakeup interrupts
IPI1: 0 0 0 0 Timer broadcast interrupts
IPI2: 1469 2966 3711 4460 Rescheduling interrupts
IPI3: 203 798 542 445 Function call interrupts
IPI4: 0 0 0 0 CPU stop interrupts
IPI5: 55 85 41 24 IRQ work interrupts
IPI6: 0 0 0 0 completion interrupts
Err: 0
I can see from this table that the SPI's are assigned with interrupts but only spi0.4 is actually activated. How can activate the other 2 interrupts for spi0.0 and spi0.5?
question from:
https://stackoverflow.com/questions/65680141/raspberrypi-3b-with-multiple-can-buses-mpc2515 
