Linux/AM3354: GPIO control in U-boot

pranav prakash55

Part Number: AM3354

Tool/software: Linux

Hello ,

I am using AM3354 ,I want to toggle a gpio pin continiously as the device is power on . Initially i want to implement the toggling in uboot and that should be retained in the kernel as it gets loaded . I am able to do this using command line but i want to implement that in code so it should get active in background as the device power on.

with regards

pranav

over 7 years ago

0 Biser Gatchev-XID over 7 years ago

TI__Guru**** 393215 points

The software team have been notified. They will respond here.

0 Cvetolin Shulev-XID over 7 years ago

TI__Guru 65405 points

Hi Pranav,

You should perform two steps to have to toggle a GPIO pin continuously as the device is power on.
1. Export and toggle the GPIO pin in the u-boot:
You should add in the u-boot/board/ti/am335x/board.c the following sequence:
#define GPIO_<YOUR_GPIO_NAME> GPIO_TO_PIN(<BANK_OF_YOUR_GPIO>, <YOUR_GPIO>)
the add in the board_init func:
REQUEST_AND_SET_GPIO(GPIO_<YOUR_GPIO_NAME>);
gpio_set_value(GPIO_<YOUR_GPIO_NAME>, 1);
and configure the GPIO_<YOUR_GPIO_NAME> in u-boot/board/ti/am335x/mux.c
2. Export and toggle the GPIO pin in the Linux kernel:
Export the GPIO in device tree as it is described at:
www.kernel.org/.../gpio.txt
and see Exporting from Kernel code section in:
www.kernel.org/.../sysfs.txt
then use gpio_set_value function.

Also see this tutorial:
derekmolloy.ie/.../

BR
Tsvetolin Shulev

0 pranav prakash55 over 7 years ago in reply to Cvetolin Shulev-XID

Intellectual 620 points

Hello sir ,

Thanks for the quick response ,but instead of setting to a particular value of 1 or 0, I want to toggle continiously so that even i stop in uboot that process should keep running .like a blinking of led .

with regards
pranav

0 Cvetolin Shulev-XID over 7 years ago in reply to pranav prakash55

TI__Guru 65405 points

Pranav,

If your target is to stop in u-boot prompt and to have ability to toggle the GPIO you should add to u-boot a new command to do that. You can find description about how to add a new u-boot command at:
github.com/.../README.commands
Then add gpio_set_value() in the function called by the added command.

BR
Tsvetolin Shulev

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Linux/AM3354: GPIO control in U-boot