Hey all, I’m in the process of writing a custom device tree for my board. Here’s what I have so far. The problem is that u-boot hangs at “starting kernel”, and I believe that this dts file is at fault somehow–maybe the interrupt parent. GPIO helper is apparently outdated too. It would be really nice if someone would suggest an overview of how to write device trees specifically with the PRU. I haven’t found a super beginner friendly resource.
/* OreSat Star Tracker v1.2 device tree */
/dts-v1/;
#include "oresat-base.dtsi"
/ {
prucam {
compatible = "psas,prucam-ar013x";
ti,prus = <&pru0>, <&pru1>;
interrupt-parent = <&pruss_intc>;
interrupts = <18 2 2>, <16 0 0>, <17 1 1>;
interrupt-names = "pru1_to_arm", "arm_to_prus", "pru0_to_pru1";
};
};
&am33xx_pinmux {
st_i2c2_pins: pinmux-st-i2c2-pins {
pinctrl-single,pins = <
AM33XX_IOPAD(AM335X_PIN_UART1_CTSN, PIN_INPUT | MUX_MODE3) /* i2c2_sda */
AM33XX_IOPAD(AM335X_PIN_UART1_RTSN, PIN_INPUT | MUX_MODE3) /* i2c2_scl */
>;
};
st_gpio_pins: pinmux-st-gpio-pins {
pinctrl-single,pins = <
/* Pins for CAM_control. */
AM33XX_IOPAD(AM335X_PIN_MII1_TXD3, PIN_INPUT | MUX_MODE7) /* gpio0_16 / FLASH */
AM33XX_IOPAD(AM335X_PIN_MII1_CRS, PIN_OUTPUT | MUX_MODE7) /* gpio3_1 / BUS_OE */
AM33XX_IOPAD(AM335X_PIN_MII1_COL, PIN_OUTPUT | MUX_MODE7) /* gpio3_0 / CAM_OE */
AM33XX_IOPAD(AM335X_PIN_MII1_RX_CLK, PIN_OUTPUT | MUX_MODE7) /* gpio3_10 / CLK_EN */
AM33XX_IOPAD(AM335X_PIN_MII1_RXD0, PIN_OUTPUT | MUX_MODE7) /* gpio2_21 / INPUT_EN */
AM33XX_IOPAD(AM335X_PIN_MII1_RXD1, PIN_OUTPUT | MUX_MODE7) /* gpio2_20 / RESET */
AM33XX_IOPAD(AM335X_PIN_MII1_RXD2, PIN_OUTPUT | MUX_MODE7) /* gpio2_19 / SADDR */
AM33XX_IOPAD(AM335X_PIN_MII1_RXD3, PIN_OUTPUT | MUX_MODE7) /* gpio2_18 / STANDBY */
AM33XX_IOPAD(AM335X_PIN_MII1_RX_ER, PIN_OUTPUT | MUX_MODE7) /* gpio3_2 / TRIGGER */
AM33XX_IOPAD(AM335X_PIN_MII1_RX_DV, PIN_OUTPUT | MUX_MODE7) /* gpio3_4 / VREG_EN */
/* Pins for CAM_parallel bus. Currently only getting top 8 bits of pixel data. */
AM33XX_IOPAD(AM335X_PIN_MCASP0_ACLKX, PIN_INPUT | MUX_MODE6) /* pr1_pru0_pru_r31_0 / CAM_D4 */
AM33XX_IOPAD(AM335X_PIN_MCASP0_FSX, PIN_INPUT | MUX_MODE6) /* pr1_pru0_pru_r31_1 / CAM_D5 */
AM33XX_IOPAD(AM335X_PIN_MCASP0_AXR0, PIN_INPUT | MUX_MODE6) /*pr1_pru0_pru_r31_2 / CAM_D6 */
AM33XX_IOPAD(AM335X_PIN_MCASP0_AHCLKR, PIN_INPUT | MUX_MODE6) /* pr1_pru0_pru_r31_3 / CAM_D7 */
AM33XX_IOPAD(AM335X_PIN_MCASP0_ACLKR, PIN_INPUT | MUX_MODE6) /* pr1_pru0_pru_r31_4 / CAM_D8 */
AM33XX_IOPAD(AM335X_PIN_MCASP0_FSR, PIN_INPUT | MUX_MODE6) /* pr1_pru0_pru_r31_5 / CAM_D9 */
AM33XX_IOPAD(AM335X_PIN_MCASP0_AXR1, PIN_INPUT | MUX_MODE6) /* pr1_pru0_pru_r31_6 / CAM_D10 */
AM33XX_IOPAD(AM335X_PIN_MCASP0_AHCLKX, PIN_INPUT | MUX_MODE6) /* pr1_pru0_pru_r31_7 / CAM_D11 */
AM33XX_IOPAD(AM335X_PIN_GPMC_AD14, PIN_INPUT | MUX_MODE6) /* pr1_pru0_pru_r31_14 / CAM_VSYNC */
AM33XX_IOPAD(AM335X_PIN_GPMC_AD15, PIN_INPUT | MUX_MODE6) /* pr1_pru0_pru_r31_15 / CAM_HSYNC */
AM33XX_IOPAD(AM335X_PIN_XDMA_EVENT_INTR1, PIN_INPUT | MUX_MODE5) /* pr1_pru0_pru_r31_16 / CAM_PXL_CLK */
>;
};
};
&i2c2 {
#address-cells = <1>;
#size-cells = <0>;
status = "okay";
pinctrl-names = "default";
pinctrl-0 = <&st_i2c2_pins>;
clock-frequency = <100000>;
};
&ocp {
cape-universal {
compatible = "gpio-of-helper";
status = "okay";
pinctrl-names = "default";
pinctrl-0 = <&st_gpio_pins>;
FLASH {
gpio-name = "FLASH";
gpio = <&gpio0 16 GPIO_ACTIVE_HIGH>; /* AM335X_PIN_MII1_TXD3 */
input;
};
BUS_OE {
gpio-name = "BUS_OE";
gpio = <&gpio3 1 GPIO_ACTIVE_HIGH>; /* AM335X_PIN_MII1_CRS */
output;
};
CAM_OE {
gpio-name = "CAM_OE";
gpio = <&gpio3 0 GPIO_ACTIVE_HIGH>; /* AM335X_PIN_MII1_COL */
output;
};
CLK_EN {
gpio-name = "CLK_EN";
gpio = <&gpio3 10 GPIO_ACTIVE_HIGH>; /* AM335X_PIN_MII1_RX_CLK */
output;
};
CAM_INPUT_EN { /* name cannot be INPUT_EN */
gpio-name = "INPUT_EN";
gpio = <&gpio2 21 GPIO_ACTIVE_HIGH>; /* AM335X_PIN_MII1_RXD0 */
output;
};
RESET {
gpio-name = "RESET";
gpio = <&gpio2 20 GPIO_ACTIVE_HIGH>; /* AM335X_PIN_MII1_RXD1 */
output;
};
SADDR {
gpio-name = "SADDR";
gpio = <&gpio2 19 GPIO_ACTIVE_HIGH>; /* AM335X_PIN_MII1_RXD2 */
output;
};
STANDBY {
gpio-name = "STANDBY";
gpio = <&gpio2 18 GPIO_ACTIVE_HIGH>; /* AM335X_PIN_MII1_RXD3 */
output;
};
TRIGGER {
gpio-name = "TRIGGER";
gpio = <&gpio3 2 GPIO_ACTIVE_HIGH>; /* AM335X_PIN_MII1_RX_ER */
output;
};
VREG_EN {
gpio-name = "VREG_EN";
gpio = <&gpio3 4 GPIO_ACTIVE_HIGH>; /* AM335X_PIN_MII1_RX_DV */
output;
};
};
};
&pruss {
status = "okay";
};
&pruss_tm {
status = "okay";
};
This is my extlinux.conf, Where fdt is the dtb for the preceding device tree.
TIMEOUT 1
DEFAULT linux
LABEL linux
KERNEL /vmlinuz-${kernel_version}
INITRD /initrd.img-${kernel_version}
FDT /dtbs/${kernel_version}/${fdt}
APPEND console=ttyS0,115200 root=/dev/mmcblk0p2 rw rootwait
