i.MX Processors中的主题 Re: Using SRTM interface to virtually access GPIOs

Using SRTM interface to virtually access GPIOs

adam_loch — Mon, 18 Nov 2019 15:06:29 GMT

We would like to be able to access GPIOs owned by the M4 on the A35 (Linux) using the SRTM service/APIs. We have a demo application for SRTM which does "virtual" I2C access, and we just want to double-check if similar functionality is possible with GPIOs. If this possible, we'd also like to understand what the capabilities are with respect to this functionality (i.e. will it do interrupts, what is the latency, is there any documentation, etc).

Re: Using SRTM interface to virtually access GPIOs

AldoG — Tue, 26 Nov 2019 00:12:51 GMT

Hello,

1.-On i.MX8MM, both M4 core and A53 core can access the same module, e.g. i2c, gpio.

User needs to setup access permissions in XRDC setting.

Also, user needs to make sure that both cores should avoid access confliction, that is, both cores should not access the same module at the same time.

2.-If GPIOs are assigned to M4 only in your case, I think A53 can send msg to M4 for GPIO operations with RPMSG communication channel.

User can refer to ttyRPMSG, rpmsg ping-pong or rpmsg character device mechanism for this (User can find str echo and ping-pong examples in M4 SDK).

In all these ways, interrupt can be supported.

For interrupt latency, method 1 is definitely faster than method 2.

Hope this helps,

Best regards,

Aldo.

Re: Using SRTM interface to virtually access GPIOs

adam_loch — Mon, 02 Dec 2019 16:16:40 GMT

Thank you - this is helpful information.

Adam

Re: Using SRTM interface to virtually access GPIOs

adam_loch — Mon, 02 Dec 2019 20:51:37 GMT

nxf46838‌ can you confirm this also applies to the i.MX8SXL and i.MX8DXL?

Thanks again,

Adam

Re: Using SRTM interface to virtually access GPIOs

AldoG — Wed, 04 Dec 2019 17:28:11 GMT

Hello,

Yes, this should also be suitable for i.MX 8SXL & i.MX 8DXL.

Thank you,

Best regards,

Aldo.