Changed the DT overlay to use SPI0 and wired MCP2515 breakout board to SPI0 on PocketBeagle. The mcp251x driver was able to initialize the device OK!
The mcp251x driver also initialized the MCP2515 device OK when connect to SPI0 on BeagleBone Black.
So why does SPI1 not work?
For SPI0 on PocketBeagle, I used:
debian@beaglebone:/opt/source/bb.org-overlays$ cat src/arm/PB-MCP2515.dts
/dts-v1/;
/plugin/;
#include <dt-bindings/gpio/gpio.h>
#include <dt-bindings/pinctrl/am33xx.h>
#include <dt-bindings/interrupt-controller/irq.h>
/ {
fragment@0 {
target = <&ocp>;
__overlay__ {
/*
M2 J4.20: SWC nINT <-> P2.8 <&gpio1 28 0>, needs GPIO input
M2 J3.6 : SWC_nRESET <-> P2.32 GPIO 112 / PRU0.2, <&gpio3 16 0>, needs GPIO OUTPUT
M2 J4.9 : SWC_M0 <-> P2.6
M2 J4.28: SWC_M1 <-> P2.18
*/
P1_12_pinmux { status = "disabled"; }; /* MOSI - gpio0_4 */
P1_10_pinmux { status = "disabled"; }; /* MISO - gpio0_3 */
P1_08_pinmux { status = "disabled"; }; /* CLK - gpio0_2 */
P1_06_pinmux { status = "disabled"; }; /* CS - gpio0_5 */
P2_08_pinmux { status = "disabled"; }; /* SWC nINT */
P2_32_pinmux { status = "disabled"; }; /* SWC nRESET */
};
};
fragment@1 {
target = <&spi0>;
__overlay__ {
status = "okay";
pinctrl-names = "default";
/*
M2 J4.20: SWC nINT <-> P2.8 <&gpio1 28 0>, needs GPIO input
M2 J3.6 : SWC_nRESET <-> P2.32 GPIO 112 / PRU0.2, <&gpio3 16 0>, needs GPIO OUTPUT
M2 J4.9 : SWC_M0 <-> P2.6 GPIO 57, needs GPIO OUTPUT
M2 J4.28: SWC_M1 <-> P2.18 GPIO 47, needs GPIO OUTPUT
*/
pinctrl-0 = <
/* connected to MCP2515 pin 19 _RESET
hopefully pullup will enable the chip */
&P2_32_gpio_pu_pin
/* SWC nINT */
/* &P2_08_gpio_input_pin is not mode 0x37, so wrong? */
&P2_08_default_pin /* this should be mode 0x37 */
/* SPI0 */
&P1_06_spi_cs_pin
&P1_08_spi_sclk_pin
&P1_10_spi_pin
&P1_12_spi_pin
>;
channel@0{ status = "disabled"; };
channel@1{ status = "disabled"; };
};
};
fragment@2 {
target = <&am33xx_pinmux>;
__overlay__ {
/*
this was originally for BeagleBone Black and used P8.06
from http://exploringbeaglebone.com/wp-content/uploads/resources/BBBP8Header.pdf
P8_06 3 0x80c/00c 35 GPIO1_3 gpio1[3]
pinctrl-single,pins = < 0x00c 0x37 >;
#0x37 : PIN_OUTPUT_PULLUP | INPUT_EN | MUX_MODE7
for PocketBeagle, Macchina puts nINT on P2.08 (ZCZ ball U18) gpio1_28
P2_08_default_pin: pinmux_P2_08_default_pin { pinctrl-single,pins = <
AM33XX_IOPAD(0x0878, PIN_OUTPUT_PULLUP | INPUT_EN | MUX_MODE7) >; }; gpmc_be1n.gpio1_28
where 0x0878 = PB_P2_08
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/dt-bindings/pinctrl/omap.h#n57
https://github.com/beagleboard/bb.org-overlays/blob/master/tools/pinmux-generator/PocketBeagle.dts#L465-L467
https://github.com/beagleboard/bb.org-overlays/blob/master/tools/pinmux-generator/lib/pinmux.sh#L631
so let's try giving pincntrl-single 0x087 which should be the offset from the 0x0800 base
*/
mcp2515_int: mcp2515_int {
pinctrl-single,pins = < 0x087 0x37 >;
};
};
};
fragment@3 {
target-path = "/";
__overlay__ {
mcp2515_clock: mcp2515_clock {
compatible = "fixed-clock";
#clock-cells = <0>;
clock-frequency = <8000000>;
};
};
};
fragment@4 {
target = <&spi0>;
__overlay__ {
#address-cells = <1>;
#size-cells = <0>;
can0: mcp2515@0 {
status = "okay";
reg = <0>;
compatible = "microchip,mcp2515";
pinctrl-names = "default";
pinctrl-0 = <&mcp2515_int>;
spi-max-frequency = <10000000>;
interrupt-parent = <&gpio1>;
interrupts = <28 2>;
clocks = <&mcp2515_clock>;
mcp251x,oscillator-frequency = <8000000>;
mcp251x,irq-gpios = <&gpio1 28 0>;
mcp251x,stay-awake = <1>;
mcp251x,enable-clkout = <1>;
};
};
};
__overrides__ {
oscillator = <&mcp2515_clock>,"clock-frequency:0";
spimaxfrequency = <&can0>,"spi-max-frequency:0";
interrupt = <&mcp2515_int>,"pinctrl-single,pins:0",<&can0>,"interrupts:0";
};
};
[ 36.889216] IPv6: ADDRCONF(NETDEV_UP): usb0: link is not ready
[ 37.183016] IPv6: ADDRCONF(NETDEV_CHANGE): usb0: link becomes ready
[ 42.103806] DEBUG SWCAN: mcp251x_can_probe(): spi->chip_select=0x00
[ 42.354826] DEBUG SWCAN: mcp251x_can_probe(): spi->irq=0x50
[ 42.530893] DEBUG SWCAN: mcp251x_can_probe(): spi->modalias=mcp2515
[ 42.781591] DEBUG SWCAN: mcp251x_can_probe(): spi->cs_gpio=0xfffffffe
[ 42.964563] DEBUG SWCAN: mcp251x_can_probe(): spi->controller->bus_num=0x00
[ 43.270939] DEBUG SWCAN: mcp251x_can_probe(): spi->dev->init_name=(null)
[ 43.526138] DEBUG SWCAN: mcp251x_can_probe(): spi->dev->bus->name=spi
[ 43.703474] c_can_platform 481cc000.can: c_can_platform device registered (regs=fa1cc000, irq=39)
[ 43.726982] DEBUG SWCAN: mcp251x_can_probe(): spi->dev->bus->dev_name=(null)
[ 43.779223] c_can_platform 481d0000.can: c_can_platform device registered (regs=fa1d0000, irq=40)
[ 43.992895] DEBUG SWCAN: mcp251x_can_probe(): freq = clk_get_rate(clk)
[ 44.250869] DEBUG SWCAN: mcp251x_can_probe(): freq=0x7a1200
[ 44.407104] DEBUG SWCAN: mcp251x_can_probe(): freq=8000000
[ 44.674954] DEBUG SWCAN: mcp251x_can_probe(): net=daa9b000
[ 44.792908] DEBUG SWCAN: mcp251x_can_probe(): ret = clk_prepare_enable(clk): 0x00
[ 44.963056] DEBUG SWCAN: mcp251x_can_probe(): call mcp251x_power_enable()
[ 45.075205] DEBUG SWCAN: mcp251x_can_probe(): call mcp251x_hw_probe()
[ 45.274882] DEBUG SWCAN: mcp251x_hw_probe: call mcp251x_hw_reset()
[ 45.373637] DEBUG SWCAN: mcp251x_hw_reset(): spriv->spi_tx_buf[0]=0xc0
[ 45.634937] DEBUG SWCAN: mcp251x_hw_reset(): call mcp251x_spi_trans(spi, 1)
[ 45.778902] DEBUG SWCAN: mcp251x_spi_trans(len=0x01): call spi_message_init()
[ 46.002989] DEBUG SWCAN: mcp251x_spi_trans(): call spi_message_add_tail(&t, &m)
[ 46.211014] DEBUG SWCAN: mcp251x_spi_trans(): call spi_sync(spi, &m)
[ 46.372847] DEBUG SWCAN: mcp251x_spi_trans(): return ret=0x00
[ 46.586661] DEBUG SWCAN: mcp251x_hw_reset(): call mcp251x_read_reg(spi, CANSTAT)
[ 46.739117] DEBUG SWCAN: mcp251x_read_reg(reg=0x0e): call mcp251x_spi_trans()
[ 46.921698] DEBUG SWCAN: mcp251x_spi_trans(len=0x03): call spi_message_init()
[ 47.126881] DEBUG SWCAN: mcp251x_spi_trans(): call spi_message_add_tail(&t, &m)
[ 47.243076] DEBUG SWCAN: mcp251x_spi_trans(): call spi_sync(spi, &m)
[ 47.408906] DEBUG SWCAN: mcp251x_spi_trans(): return ret=0x00
[ 47.528872] DEBUG SWCAN: mcp251x_read_reg(): return val=0x80
[ 47.706895] DEBUG SWCAN: mcp251x_hw_reset(): reg=0x80
[ 47.851419] DEBUG SWCAN: mcp251x_hw_reset(): (reg & CANCTRL_REQOP_MASK)=0x80
[ 48.007196] DEBUG SWCAN: mcp251x_hw_probe: ret=0
[ 48.114939] DEBUG SWCAN: mcp251x_hw_probe: call mcp251x_read_reg(spi, CANCTRL)
[ 48.114963] DEBUG SWCAN: mcp251x_read_reg(reg=0x0f): call mcp251x_spi_trans()
[ 48.446946] DEBUG SWCAN: mcp251x_spi_trans(len=0x03): call spi_message_init()
[ 48.590916] DEBUG SWCAN: mcp251x_spi_trans(): call spi_message_add_tail(&t, &m)
[ 48.810969] DEBUG SWCAN: mcp251x_spi_trans(): call spi_sync(spi, &m)
[ 48.938944] DEBUG SWCAN: mcp251x_spi_trans(): return ret=0x00
[ 49.039159] DEBUG SWCAN: mcp251x_read_reg(): return val=0x87
[ 49.242932] DEBUG SWCAN: mcp251x_hw_probe: ctrl=0x87
[ 49.307830] DEBUG SWCAN: mcp251x_hw_probe: ((ctrl & 0x17)=0x07
[ 49.462455] mcp251x spi0.0: CANCTRL 0x87
[ 49.462467] DEBUG SWCAN: mcp251x_spi_trans(len=0x03): call spi_message_init()
[ 49.618942] DEBUG SWCAN: mcp251x_spi_trans(): call spi_message_add_tail(&t, &m)
[ 49.814674] DEBUG SWCAN: mcp251x_spi_trans(): call spi_sync(spi, &m)
[ 49.962984] DEBUG SWCAN: mcp251x_spi_trans(): return ret=0x00
[ 50.114968] mcp251x spi0.0 can2: MCP2515 successfully initialized.
debian@beaglebone:~$
the other change made at the same time I switched SPI1 to SPI0, I changed interrupts = <3 2>; to interrupts = <28 2>; based on advise from Robert Nelson
interrupts = <28 IRQMODE>;https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/dt-bindings/interrupt-controller/irq.h#n15#define IRQ_TYPE_EDGE_FALLING 2
