SPI chip on RPi3, need to configure CS and IRQ

R

rt9f3

Hello,

I'm running 14.2 on an RPi3 (BCM2837), I'd like to interface with a custom board via SPI wired to SPI0 (/dev/spigen0.0).
The board uses GPIO8 for CS and can generate an IRQ on GPIO17. The IRQ could be used to trigger data transfer.

How do I get spigen to use GPIO8 for CS?

I'd like to service this board from userland with a high priority RT handler thread waiting on IRQ. How can I do this in FreeBSD?

Thanks,
 
You cant really force a certain pin to be SPI it has to be one of the pins that is muxed for SPI-CS

github.com

firmware/boot/overlays at master · raspberrypi/firmware

This repository contains pre-compiled binaries of the current Raspberry Pi kernel and modules, userspace libraries, and bootloader/GPU firmware. - raspberrypi/firmware
github.com github.com

FreeBSD complies these for you so all you need to do is copy them from /usr/local/share/rpi-firmware/ to /boot/dtb/overlays and declare them in config.txt
Note that everything from this repository is compiled yet not all dtb will work on FreeBSD. You need to have a corresponding driver for some of these overlays.
 
Thank you. I see, the selection of CS0 vs CS1 for SPI0 is encoded with the device name (/dev/spigen0.0 for CE0). This is perfect, CS0 is GPIO8.

The remaining question is how do I configure GPIO17 to generate an interrupt (level triggered) and how do I configure a pthread to wait on it? If a kmod is required, what's the best (lightest overhead) mechanism to wake/notify a waiting pthread? I've seen gpioctl but it doesn't support interrupts.
 
Here is a post I was looking for when I posted the above references. obsigna is really on point here:

O

Post in thread 'GPIO API general (Orange Pi ... H3)'

aragats said:
gpioctl() doesn't list INTR* caps/flags, obviously it won't accept such configuration.
Interrupts are processed by kernel, it's not clear how to use them in user space.
Within a commercial project I'm involved in I wrote a Linux kernel module, which sends a signal to a userland program when an interrupt occurs. I'm not sure whether such approach is acceptable in general though.
Click to expand...
Here comes a tiny C program which utilizes the user space interrupts facility for receiving events from a rotary encoder and some buttons which are attached to GPIO pins of the BBB. Interrupt processing...
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A

Thread 'How to apply for GPIO interrupt in kernel'

Hi everybody,
Recently I transplanted an i2c device to FreeBSD on Raspberry 3b+, and needed to use a GPIO interrupt function. When using the gpio_alloc_intr_resource () function, it always returned NULL. I don’t know what went wrong.
And attach DTS configuration :
Code: 
touchscreen@5d {
     compatible = "goodix,gt9886";
     reg = <0x5d>;
     interrupt-parent = <&gpio>;
     interrupts = <6 IRQ_TYPE_EDGE_FALLING>;
     goodix,irq-gpio = <&gpio 6 GPIO_ACTIVE_HIGH>;
};
 
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