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Adventurer
Adventurer
693 Views
Registered: ‎01-24-2018

RPU Device Tree Entry

In the OpenAMP 2018.1 wiki there is this line in a dtsi example...

 

 test_r50: zynqmp_r5_rproc@0 {
            compatible = "xlnx,zynqmp-r5-remoteproc-1.0";
            reg = <0x0 0xff9a0100 0 0x100>, <0x0 0xff340000 0 0x100>, <0x0 0xff9a0000 0 0x100>;
 
My question is, where did these (in red) numbers come from and how do I decode them please?
 
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4 Replies
Moderator
Moderator
679 Views
Registered: ‎05-10-2017

Re: RPU Device Tree Entry

0xFF9A0100 is the rpu0 cfg register

0xFF9A0000 is the rpu_glb_cntl register

0xFF340000 is the CH7_TRIG IPI register. This is used because the default APU IPI is being used for atf and pmufw.

 

These registers are also described in the reg-names in the node description

reg = <0x0 0xff9a0100 0x0 0x100>,
 <0x0 0xff340000 0x0 0x100>,
 <0x0 0xff9a0000 0x0 0x100>;
 reg-names = "rpu_base", "ipi", "rpu_glbl_base";

Please see UG1087 for detailed register descriptions

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Adventurer
Adventurer
675 Views
Registered: ‎01-24-2018

Re: RPU Device Tree Entry

Ah... okay, I get it now.

 

reg = <>

 

I get that the second value is the register address now.  ;)

 

So what are the other three value please that are inside the <> along with the register address?

 

In this example the register address is always preceded by 0x0, and is always followed by 0x0 0x100.

 

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Moderator
Moderator
650 Views
Registered: ‎05-10-2017

Re: RPU Device Tree Entry

This is 64-bit addressing. Please see reg property in the device-tree specification doc

https://www.devicetree.org/downloads/devicetree-specification-v0.1-20160524.pdf

 

You can also see How addressing works section in this link

https://elinux.org/Device_Tree_Usage#How_Addressing_Works

 

 

0x0 0xff9a0100 - This denotes the base address

0 0x100 - This denotes the length

 

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Adventurer
Adventurer
615 Views
Registered: ‎01-24-2018

Re: RPU Device Tree Entry

Thanks jovitac, I will look these over

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