SK-AM62B: Using MCU_I2C0 / WKUP_I2C0 on AM625 evaluation board from the A53

Hello Jeremiah,

1) Please share your boot logs showing the I2C bus getting probed

2) Please share your devicetree modifications

3) What version of Linux SDK are you using?

4) What boot flow are you using? SBL? SPL?

For more information about boot flows, refer to the AM62x academy's multicore module:

https://dev.ti.com/tirex/explore/node?node=A__AZdBTlT8UK2hNwHKXaPieQ__AM62-ACADEMY__uiYMDcq__LATEST

Regards,

Nick

1) The I2C driver probes without error and a /dev/i2c device is created, however the devices on the I2C bus fail to probe (a TMP42X sensor and a AT24x EEPROM both fail to probe).

2) R5 device tree was modified to replace DDR config for the AM625 non SIP with DDR config for the AM625SIP from the SDK, we are including the buildroot k3-am625.dtsi and setting the mcu_i2c0 status to be equal to "okay". We have also tried this on the evaluation board with it's GPIO expander using the wkup_uart0, it observes the exact same behavior as the evaluation board.

3) We are using buildroot 2025 with the latest versions of Linux and Uboot, no modifications or patches aside from those included in the buildroot defconfig for the am62x evaluation board have been made.

4) We are using the Uboot SPL, the only change we have made was to enable DEBUG_UART in the R5 and the A53 SPLs.

DTS for our custom hardware is attached, we are only using this DTS for the Linux image, uboot and everything else still use the same DTS as what's configured in buildroot, However I am currently WFH and not in the lab so I cannot share boot logs, however Monday I will boot the board and upload logs:

#include "k3-am625.dtsi"

#include <dt-bindings/gpio/gpio.h>

/ {
	aliases {
		serial2 = &main_uart0;
		mmc0 = &sdhci0;
		mmc1 = &sdhci1;
		ethernet0 = &cpsw_port1;
	};

	chosen {
		stdout-path = "serial2:115200n8";
	};

	memory@80000000 {
		/* 512MB RAM */
		reg = <0x00000000 0x80000000 0x00000000 0x20000000>;
		device_type = "memory";
		bootph-pre-ram;
	};

	reserved-memory {
		#address-cells = <2>;
		#size-cells = <2>;
		ranges;

		ramoops@9ca00000 {
			compatible = "ramoops";
			reg = <0x00 0x9ca00000 0x00 0x00100000>;
			record-size = <0x8000>;
			console-size = <0x8000>;
			ftrace-size = <0x00>;
			pmsg-size = <0x8000>;
		};

		/* global cma region */
		linux,cma {
			compatible = "shared-dma-pool";
			reusable;
			size = <0x00 0x8000000>;
			linux,cma-default;
		};

		secure_tfa_ddr: tfa@9e780000 {
			reg = <0x00 0x9e780000 0x00 0x80000>;
			alignment = <0x1000>;
			no-map;
		};

		secure_ddr: optee@9e800000 {
			reg = <0x00 0x9e800000 0x00 0x01800000>; /* for OP-TEE */
			alignment = <0x1000>;
			no-map;
		};

		wkup_r5fss0_core0_dma_memory_region: r5f-dma-memory@9db00000 {
			compatible = "shared-dma-pool";
			reg = <0x00 0x9db00000 0x00 0xc00000>;
			no-map;
		};
	};

	tlv320_mclk: clk-0 {
		#clock-cells = <0>;
		compatible = "fixed-clock";
		clock-frequency = <12288000>;
	};
};

&main_uart0 {
	bootph-all;
	status = "okay";
};

&mcu_i2c0 {
	status = "okay";

	temp_u123 {   /* TI TMP42X sensor */
		status = "okay";
		compatible = "ti,tmp422";
		reg = <0x4C>;

		/* channels removed for proprietary data */
	};

	eeprom_u123 { /* AT 24 EEPROM */
		status = "okay";
		compatible = "atmel,24c02";
		reg = <0x50>;
	};
};

/* sdhci0 and sdhci1 removed for proprietary data */

/* cpsw3g removed for proprietary data */

/* The below nodes are magically make things work, leave them alone */

&mailbox0_cluster0 {
	mbox_m4_0: mbox-m4-0 {
		ti,mbox-rx = <0 0 0>;
		ti,mbox-tx = <1 0 0>;
	};
};

/* The following device tree items are reserved for TI FW usage */

&mcu_gpio0 {
	status = "reserved";
};

&mcu_gpio_intr {
	status = "reserved";
};

&wkup_uart0 {
	/* WKUP UART0 is used by DM firmware */
	bootph-pre-ram;
	status = "reserved";
};
&main_uart1 {
	/* Main UART1 is used by TIFS firmware */
	bootph-pre-ram;
	status = "reserved";
};