Part 1: LEDs w/ PL(CLK)
GPIO(test)
There is a list of drivers for linux. As per the gpio driver, let’s test the:
- USER_LED1(0)
- USER_LED2(9)
- SW1(50)
Let’s identify the GPIOChip:
Looking at /sys/class/gpio:
root@spyros:~# cd /sys/class/gpio/
root@spyros:/sys/class/gpio# grep . */*
gpiochip1022/base:1022
gpiochip1022/label:41210000.gpio
gpiochip1022/ngpio:1
gpiochip1023/base:1023
gpiochip1023/label:41200000.gpio
gpiochip1023/ngpio:1
gpiochip904/base:904
gpiochip904/label:zynq_gpio
gpiochip904/ngpio:118
Apparently, gpiochip904 will contain the PS(GPIO). As per the driver:
904: defines the base118: defines the amount
Thus, our PS(GPIO) pins are from 904 + 0 to 904 + 118.
[From previous chapters], We need MIO(0, 9 and 50):
Export the pins: Fix the directions:
$ echo $((904 + 0)) > export
$ echo out > gpio$((904 + 0))/direction
$ echo $((904 + 9)) > export
$ echo out > gpio$((904 + 9))/direction
$ echo $((904 + 50)) > export
(The remaining 1022/1023 gpios are AXI(button in) and AXI(CLK out). They both work).
Crude notes
- rename nets and elements. Changes for dts (components).
- dtc -I fs /sys/firmware/devicetree/base
- &gpio0 (LEDs)
- /usr/src/linux/uapi/linux/input/input-event-codes.h
- reference to root
- /dev/input/by-path/platform-buttons-event (hexdump) < evtest
- build essential
- CONFIG_nano https://support.xilinx.com/s/question/0D52E00006xnpfBSAQ/add-nano-editor-to-petalinux-20202?language=en_US
- evtest button
IMAGE_INSTALL_append = “kernel-devsrc” vitis- merge downloads (w/ .done)
- first-boot checklist
- https://www.zachpfeffer.com/single-post/Execute-a-Script-at-Boot-Using-PetaLinux-Tools
- https://support.xilinx.com/s/question/0D52E00006hpaIgSAI/getting-a-kernel-module-to-load-at-start-up?language=en_US
DMA:
- https://support.xilinx.com/s/question/0D52E00006hpc0zSAA/axi-dma-tutorialexample-with-zynq-running-linux?language=en_US
- https://lauri.võsandi.com/hdl/zynq/xilinx-dma.html
- simply by reading/writing to a memory mapped range from /dev/mem
- Start the DMA channel (MM2S, S2MM or both) by writing 1 to control register
- Write start/destination addresses
- write transfer length(s)
- a sanitized way of accessing the hardware from userspace applications via /dev/blah block devices
- https://docs.xilinx.com/access/sources/framemaker/map?Doc_Version=7.1 English&url=pg021_axi_dma > register addresses
troubleshooting
- error fetching (gitlab rename) (take git) (build keep done delete .git)
Interrupt from PL(downscaled CLK)
Let’s try to handle AXI(CLK out) as an interrupt.
Referencies