How to get into U-boot shell?

[parthghughri]

As per Testing section:

> Boot your board and once the U-Boot bootloader starts, interrupt to enter commands:
> 
> tpm2 init
> tpm2 startup TPM2_SU_CLEAR
> tpm2 get_capability 0x6 0x106 0x200 2
> 
> For an Infineon TPM you should get 0x534c4239 and 0x36373000 which is hex for SLB9670. Congrats!

I am using Raspberry pi 4 model B with Infineon TPM 9670.

How we can interrupt and get U-boot shell. In my case it is directly booting to the Linux kernel. It will be really helpful if you can help me with that. Thank you in advance.

[parthghughri]

Update: I tried to interrupt the boot process by repeatedly pressing 'Esc' but got a black screen. I tried to edit u-boot's boot.scr file and removed all contents so that it won't boot the kernel. But the same result, got a black screen.

Suggestions are appreciated. Thank you

[joholl]

You're supposed to be prompted with a "press any key to enter U-Boot shell" or something similar. If you do not press a key within something like 2s, it continues booting into linux.

Hm, hard to say, really. Maybe it does not even boot into U-Boot, first. Do you have kernel=u-boot.bin in your /boot/config.txt?

When you boot into linux, your serial console (via UART, not HDMI) works, right? That is, do you see the linux boot log on the screen?

[parthghughri]

Thank you for the response. Actually, the issue was with the UART cable I am having. I used another one and I got the U-boot shell. But now the issue I am facing is exactly same as #7, solution mentioned there seems not working for me. I read the TPM device tree, so is there any issue with the gpio-reset pin brcm pin (line 4 and line 18 below)? Looks like pin 24 is getting overlapped. (I am very new to this things so the question might seem silly, feel free to correct me :))

Thank you.

1. slb9670: slb9670@0 {
2.              compatible = "infineon,slb9670", "tis,tpm2-spi", "tcg,tpm_tis-spi";
3.              reg = <0>;
4.              gpio-reset = <&gpio 24 1>;
5.              #address-cells = <1>;
6.              #size-cells = <0>;
7.              status = "okay";
8. 
9.              /* for kernel driver */
10.                 spi-max-frequency = <1000000>;
11.             };
12.         };
13.     };
14. 
15.     fragment@1 {
16.         target = <&spi0_gpio7>;
17.         __overlay__ {
18.             brcm,pins = <7 8 9 10 11 24>;
19.             brcm,function = <0>;
20.         };
21.     };

[joholl]

I don't think that is the problem. By the way: if you do not use/connect the reset pin, it should work fine, as well. Unfortunately, I do not have any time to look into that any further.

Please let us know if/how you fixed your issue.

[joholl]

Gone stale.