AM625: How to set a specific GPIO to High in uboot

Také

Part Number: AM625

I would like to set a specific GPIO to High/Low as follows

GPIO0_10:High
GPIO1_12:Low

To accomplish this, we have added the following code.

// k3-am625-sk.dts
&main_pmx{
    mygpios: mygpio{
        pinctrl-single,pins = <
			AM62X_IOPAD(0x0028, PIN_INPUT, 7) /* (J22) OSPI0_D7.GPIO0_10 */
			AM62X_IOPAD(0x01a8, PIN_INPUT, 7) /* (D20) MCASP0_AFSX.GPIO1_12 */
        >;
    };
};
&main_gpio0{
    status = "okay";
    pinctrl-names = "default";
    pinctrl-0 = <&mygpios>;
};

// evm.c
int board_late_init(void){
    int gpio_num = 409;
    if(gpio_request(gpio_num, "GPIO") < 0){
        printf("GPIO failed\n");
    }else{
        gpio_direction_output(gpio_num, 1);
        gpio_set_value(gpio_num, 1);
    }
    ...
}

I expect GPIO to be set high during u-boot initialization, but it fails with a GPIO failed message at startup.

Is there an error in procedure? Also, if there is a better way to do this, please let me know.

The original source code was taken from

git.ti.com/.../ti-u-boot.git

Thank you in advance.

over 1 year ago

0 Anshu Madwesh over 1 year ago

TI__Mastermind 19055 points

Hello,

From the device tree, I don't see any issues.

Where did you get 409 from to assign to gpio_num?

Can you try using the U-Boot GPIO commands? https://docs.u-boot.org/en/latest/usage/cmd/gpio.html

Best Regards,

Anshu

0 Také over 1 year ago in reply to Anshu Madwesh

Prodigy 30 points

Hello, Thanks for your response.

The GPIO commands in uboot are not available, but I have checked that the GPIO voltage changes by echoing 1/0 to /sys/class/gpio/gpio409/value on Linux.

=> gpio status
Unknown command 'gpio' - try 'help'

root@am62xx-evm:/sys/class/gpio/gpio409# echo 0 >./value
root@am62xx-evm:/sys/class/gpio/gpio409# echo 1 >./value

I am using the same number as specified in Linux, but with uboot will it be a different number?
If so, do I need to change the uboot build settings and enable the gpio command?

0 Anshu Madwesh over 1 year ago in reply to Také

TI__Mastermind 19055 points

Hello,

You'll need to enable CONFIG_CMD_GPIO in the U-Boot Build.

The 409 should be fine. It shouldn't change unless you change the GPIO allocation.

Best Regards,

Anshu

0 Také over 1 year ago in reply to Anshu Madwesh

Prodigy 30 points

I have followed the following steps to build, I have opened the menuconfig of am62x_evm_r5_defconfig,am62x_evm_a53_defconfig and enabled CONFIG_CMD_GPIO, but I have not found any errors in include/common.h:16's include/ config.h:4:10 at include/common.h:16, but it failed with No such file or directory.

https://software-dl.ti.com/processor-sdk-linux/esd/AM62X/08_03_00_19/exports/docs/linux/Foundational_Components/U-Boot/UG-General-Info.html

GPIO assignments have not been changed and should probably be the same as in Linux.

Currently, I am setting the GPIO H/L from a homebrew script written in Linux systemd, which takes a few seconds to execute, so I am trying to initialize it faster and am trying to see if I can set it from uboot.
If this could be accomplished in any other way, it would be fine, but do you have any means of doing this?

Best regards.

0 Anshu Madwesh over 1 year ago in reply to Také

TI__Mastermind 19055 points

Hi,

Another possible way is to directly write the GPIO register from the U-Boot prompt. I've not validated this myself.

I recommend you review '14.8.2.1 GPIO Registers' in the AM62x Technical Reference Manual: https://www.ti.com/lit/ug/spruiv7b/spruiv7b.pdf

You'll need to determine which bank contains the pin you are wanting to toggle.

Best Regards,

Anshu

0 Také over 1 year ago in reply to Anshu Madwesh

Prodigy 30 points

Hello, Anshu. Thank you for the information.

Now that the gpio command is available, I have tried it and the following is what I get.
Is there a wrong number to specify?

=> gpio set 409
i2c_write: error waiting for data ACK (status=0x116)
pca953x gpio@22: Error reading output register
GPIO: '409' not found
Command 'gpio' failed: Error -121
=> gpio clear 409
i2c_write: error waiting for data ACK (status=0x116)
pca953x gpio@22: Error reading output register
GPIO: '409' not found
Command 'gpio' failed: Error -121
=>

If I can't reference it, does that mean it is not GPIO and the number I specify is wrong?
In other words, is there a mistake in the dts address, etc.?

Thank you in advance for your help

0 Také over 1 year ago in reply to Také

Prodigy 30 points

There seems to be a mistake in the command activation, as gpio status cannot be done correctly either...

0 Anshu Madwesh over 1 year ago in reply to Také

TI__Mastermind 19055 points

Hi,

From what you provided, the U-Boot GPIO commands are still not enabled. If you are still having U-Boot config compilation errors, we can loop in the U-Boot subject matter expert. Or you can try using the register writes.

Best Regards,

Anshu

0 Také over 1 year ago in reply to Anshu Madwesh

Prodigy 30 points

Thank you for your advice.
I have posted a new question below about the gpio command.

e2e.ti.com/.../am625-how-to-enable-gpio-command-in-u-boot

0 Anshu Madwesh over 1 year ago in reply to Také

TI__Mastermind 19055 points

Thank you. We will continue the discussion in the other thread.

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AM625: How to set a specific GPIO to High in uboot