Comments on: Interrupt definitions in DTS (device tree) files for Xilinx Zynq-7000 / ARM

By: cook

cook — Tue, 14 Sep 2021 21:10:49 +0000

This is great. Thanks for the writeup!

By: Alex Matveev

Alex Matveev — Fri, 24 Feb 2017 11:57:09 +0000

Thanks for the article.

One correction though: you got SPI flag values wrong. SPI corresponds to zero value, see:
- handling in gic_irq_domain_translate() (in either drivers/irqchip/irq-gic.c or drivers/irqchip/irq-gicv3.c),
- definitions in include/dt-bindings/interrupt-controller/arm-gic.h,
- description in Documentation/devicetree/bindings/interrupt-controller/arm,gic.txt.

By: Kyle

Kyle — Thu, 24 Jul 2014 21:07:31 +0000

Thanks again.

By: eli

eli — Thu, 24 Jul 2014 19:45:05 +0000

Hi,

The DTS file is compiled into a DTB by the dtc compiler, and it interprets both hex numbers and decimal properly. It’s therefore quite far-fetched to blame the hex vs. decimal representation of constants.

Eli

By: Kyle

Kyle — Thu, 24 Jul 2014 19:41:43 +0000

format issues.

interrupt-parent = &ps7_axi-interconect_0
interrupts = 0 5 4, 0 6 4
reg = 0xf8891000 0x1000, 0xf8893000 0x1000

By: Kyle

Kyle — Thu, 24 Jul 2014 19:39:02 +0000

I’ve been working on booting a custom configuration using a Zedboard and I’m currently digging into the dtb. I noticed an inconsistency between your example and the file from the linux-xlnx-master repository in the directory arch\arm\boot\dts\zynq-zed.dts. You list your interrupt configuration values in hex whereas the downloaded dts does not appear to be in hex. Would you expect that this will cause an issue? I was thinking that it might not matter at runtime but I’ve learned that it’s not wise to assume that the provided materials are error free.

from the zynq-zed.dts file:

pmu {
compatible = “arm,cortex-a9-pmu”;
interrupt-parent = ;
interrupts = , ;
reg = , ;
reg-names = “cpu0″, “cpu1″;
} ;

Thanks for blogging.

By: Sven

Sven — Wed, 22 May 2013 07:24:15 +0000

I have now narrowed down the problem. Here it says how to configure the device tree with PPI: http://www.mjmwired.net/kernel/Documentation/devicetree/bindings/arm/gic.txt

So my interrupts entry in the DTS file looks like this for the signal Core1_nFIQ, rising edge:
12 = 28 – 16, the range for PPI interrupts is 0..15

Unfortunately the kernel is not willing to insert the module. irq_settings_is_per_cpu_devid fails in request_threaded_irq. The problem might be, that an IRQ with number as low as 19 don’t exist. When I list all IRQs in /proc they only start at number 16.

By: Sven

Sven — Wed, 22 May 2013 06:15:19 +0000

Hi Eli,

thanks for your response. Unfortunately I am not able to find the information I am looking for on the page you have provided.

Sven

By: eli

eli — Tue, 21 May 2013 15:27:45 +0000

Maybe this helps:

http://xillybus.com/tutorials/device-tree-zynq-4

By: Sven

Sven — Tue, 21 May 2013 14:50:22 +0000

Hi everyone. Is it actually possible to handle PPI interrupts with Linux in a SMP configuration? I am thinking about the Core0_nIRQ or Core1_nIRQ signals. If so, what is different in the implementation and how do I calculate the interrupt number? Thanks.

Sven