AM625: Is there any good way to control gpio by name in kernel driver?

stephen zhang

Intellectual 370 points

Part Number: AM625

Tool/software:

Is there a kernel layer similar to libgpiod that operates GPIO by name?

3 months ago

0 Bin Liu 3 months ago

TI__Guru**** 168311 points

Hi Stephen,

No, kernel doesn't use GPIO by name.

In kernel devicetree, gpio pins are specified according to gpio devicetree bindings, for example:

    vdd_sd_dv: regulator-4 {
      ...
        gpios = <&main_gpio0 31 GPIO_ACTIVE_HIGH>;
    };

Then the kernel driver uses kernel gpiod framework API to initialize and use the GPIO pins.

0 stephen zhang 3 months ago in reply to Bin Liu

Intellectual 370 points

Hi Bin,

Our project includes many character device drivers using the traditional method (with module_inti and module_exit). I tried to use devm_gpiod_get to access the gpio node defined in the device tree, but it failed to get the gpio.

Later, I finded that it might be necessary to convert the driver to the platform driver model in order to use the gpiod framework.

Is this actually the case? Can a driver implemented using the traditional method directly make use of the gpiod framework?

+1 Bin Liu 3 months ago in reply to stephen zhang

TI__Guru**** 168311 points

Hi Stephen,

No, you don't have to convert your driver to platform driver to use gpiod API. You can directly use gpiod_* functions implemented in gpio/gpiolib.c, such as gpiod_get(), gpiod_get_optional(), or gpiod_get_index_optional(), etc.

Search the kernel drivers/ directory for any example.

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AM625: Is there any good way to control gpio by name in kernel driver?