PROCESSOR-SDK-AM335X: Missing EQEP device and driver

Stephen Nguyen

Prodigy 60 points

Part Number: PROCESSOR-SDK-AM335X

How do I got about adding the EQEP subsystem to the device tree and load the drivers?

I'm using the Processor SDK Linux for AM335X 07_03_00.

I looked at other kernel version but it does not appear in 5.4.

I patched am33xx-l4.dtsi to include:

eqep0: counter@180 {
	compatible = "ti,am3352-eqep";
	reg = <0x180 0x80>;
	clocks = <&l4ls_gclk>;
	clock-names = "sysclkout";
	interrupts = <79>;
	status = "disabled";
};

But am unsure how to load the kernel driver as it does not exist in the menuconfig for tisdk_am335x-evm_defconfig

Thank you

over 4 years ago

+1 Nick Saulnier over 4 years ago

TI__Guru** 110030 points

Hello Stephen,

TI does not offer Linux driver support for the eQEP functionality of the AM335x PWMSS. You can find information about the parts of the PWMSS that we support in Linux in the SDK documentation: https://software-dl.ti.com/processor-sdk-linux/esd/docs/07_03_00_005/linux/Foundational_Components/Kernel/Kernel_Drivers/PWM.html

The AM335x processor hardware is capable of many different things, and our software team does not have the resources to enable every hardware feature in every operating system. Since we have not developed a driver, adding a devicetree node with a custom compatible string will not do anything because the Linux kernel does not have a driver that lists that compatible string. (e.g., you can find the usage of PWMSS and it's compatible string in Documentation/devicetree/bindings/pwm/pwm-tipwmss.txt).

Regards,

Nick

0 Stephen Nguyen over 4 years ago in reply to Nick Saulnier

Prodigy 60 points

The eQEP functionality exists in TISDK 08_00_00_00. I've managed to use that to enable eQEP and am able to use it.

Processors

Processors forum

PROCESSOR-SDK-AM335X: Missing EQEP device and driver