Accessing B19 GPIO in Jetson Tx2-reg

Autonomous Machines Jetson & Embedded Systems Jetson TX2
1

Hi,

We are using Jetson Tx2 in our project. We need to check the status of the GPIO11_AP_WAKE_BT (B19) GPIO pin. By referring to Google and previous forum references, we understood that we need to find the GPIO number and then we can export the same and use the pin.

We referred the Jetson TX2 pin mux template and found GPIO3_PI.05 as the GPIO pin mux. We have calculated the GPIO number as 320 + ((8*8)+5) = 389.

We have exported the same in sys/class/gpio/ but we are unable to read the GPIO status.

Please help me for reading B19 GPIO status.

2

hello janarthanamb,

We have exported the same in sys/class/gpio/ but we are unable to read the GPIO status.
may I have more details,
did you saw any error message pop-up while you access the sysnode?
thanks

3

Hello Jerry,

By referring to previous forum discussions, we are able to access the GPIO from sysfs.

We have one more query. We want to use GPIO_EXP0_INT ( A23) as Interrupt pin (input mode).

Could you please tell me in which dts file I need to add the entry for using as interrupt pin?

Thanks,
Jana

4

hello janarthanamb,

please refer to Tegra Linux Driver Package TX1 Adaptation Guide, check the [GPIO] session about how to make interrupt request.
thanks

5

Hello Jerry,

We are using Jetson TX2. Is the same document applicable for TX2 also?

Thanks,
Jana

6

hello janarthanamb,

yes, there’s example for how to make an interrupt request in dts file.
suggest you disassembler the t186.dtb file into txt file for checking,
for example,

dtc -I dtb -O dts -o outputs.txt tegra186.dtb
7

Hello Jerry,

We are able to find below example in that guide you referred,

[i]bcmdhd_wlan {
compatible
= “android,bcmdhd_wlan”;
interrupt

parent = <&gpio>;
interrupts = <TEGRA_GPIO(H, 2) 0x14>;
wlan

pwr

gpio = <&gpio TEGRA_GPIO(H, 0) 0>;
status = “okay”;
};
[/i]

Do we need to add entry in this dtb file tegra186-quill-p3310-1000-c03-00-base.dtb ? Because we are not aware which file we need to modify ?

Do you have reference link or forum discussion regarding this?

If i wan to use GPIO_EXP0_INT ( A23) as interrupt then what are the configurations i need to do with respect to above code?

Please advise,

Thanks,
Jana

8

Hello Jerry,

We have searched previous discussion and found the below link,

https://devtalk.nvidia.com/default/topic/991510/jetson-tx1/enabling-gpio-interrupts-in-kernel-driver-/?offset=11#5316159

Those guy tried to use gpio(B23 - TOUCH_RST) as interrupt in TX1 module.

But in my case it is GPIO_EXP0_INT (A23 ) in TX2. Can i use like that ? or is this different.

Thanks,
Jana