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Message-Id: <CFCE0FAF-991B-487B-A684-09A04EFC3F46@konsulko.com>
Date: Tue, 21 Jun 2016 13:24:43 +0300
From: Pantelis Antoniou <pantelis.antoniou@...sulko.com>
To: Jan Kiszka <jan.kiszka@...mens.com>
Cc: Mark Rutland <mark.rutland@....com>,
devicetree <devicetree@...r.kernel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Jailhouse <jailhouse-dev@...glegroups.com>,
Måns Rullgård <mans@...x.de>,
Antonios Motakis <antonios.motakis@...wei.com>
Subject: Re: Using DT overlays for adding virtual hardware
Hi Jan,
> On Jun 21, 2016, at 13:13 , Jan Kiszka <jan.kiszka@...mens.com> wrote:
>
> Hi Pantelis,
>
> coming back to this topic:
>
> On 2016-06-09 08:03, Jan Kiszka wrote:
>> OK, trial and error, and some interesting insights: I've played with DT
>> fragments and the overlay configfs patch of Pantelis [1] to have a
>> convenient start. Interestingly, I wasn't able to load a fragment that
>> followed the format specification for overlays ("Failed to resolve
>> tree"). By chance, I got this one working:
>>
>> /dts-v1/;
>> / {
>> fragment {
>> target-path = "/soc@...00000";
>> __overlay__ {
>> #address-cells = <2>;
>> #size-cells = <2>;
>>
>> vpci@...000000 {
>> compatible = "pci-host-cam-generic";
>> device_type = "pci";
>> #address-cells = <3>;
>> #size-cells = <2>;
>> reg = <0 0x2000000 0 0x1000000>;
>> ranges =
>> <0x02000000 0x00 0x10000000 0x00 0x10000000 0x00 0x30000000>;
>> };
>> };
>> };
>> };
>>
>> It successfully makes a BananaPi kernel add a pci host with the
>> specified config space and MMIO window.
>>
>> [ 81.619583] PCI host bridge /soc@...00000/vpci@...000000 ranges:
>> [ 81.619610] No bus range found for /soc@...00000/vpci@...000000, using [bus 00-ff]
>> [ 81.619634] MEM 0x10000000..0x3fffffff -> 0x10000000
>> [ 81.620482] pci-host-generic 2000000.vpci: ECAM at [mem 0x02000000-0x02ffffff] for [bus 00-ff]
>> [ 81.620779] pci-host-generic 2000000.vpci: PCI host bridge to bus 0000:00
>> [ 81.620801] pci_bus 0000:00: root bus resource [bus 00-ff]
>> [ 81.620814] pci_bus 0000:00: root bus resource [mem 0x10000000-0x3fffffff]
>> [ 81.620851] PCI: bus0: Fast back to back transfers enabled
>>
>> So, no /plugin/ statement, no phandles resolution. This format even
>> builds with the in-kernel dtc. Any explanations? Does the code make
>> sense (at least it builds without warnings)?
>>
>> Now I need to back this with some code in Jailhouse.
>
> Meanwhile I got a virtual PCI device recognized by Linux when running
> over Jailhouse. However, my hack above doesn't get me to proper
> interrupt mapping yet. This is what I was trying with upstream dtc:
>
> /dts-v1/;
> / {
> compatible = "lemaker,bananapi", "allwinner,sun7i-a20";
>
> fragment@0 {
> target-path = "/soc@...00000";
> __overlay__ {
> #address-cells = <2>;
> #size-cells = <2>;
>
> vpci@...0000 {
> compatible = "pci-host-ecam-generic";
> device_type = "pci";
> bus-range = <0 0>;
> #address-cells = <3>;
> #size-cells = <2>;
> #interrupt-cells = <1>;
> interrupt-map-mask = <0 0 0 7>;
> interrupt-map = <0 0 0 1 &gic 0 0 0 123 4>,
> <0 0 0 2 &gic 0 0 0 124 4>,
> <0 0 0 3 &gic 0 0 0 125 4>,
> <0 0 0 4 &gic 0 0 0 126 4>;
> reg = <0 0x2000000 0 0x100000>;
> ranges =
> <0x02000000 0x00 0x10000000 0x00 0x10000000 0x00 0x30000000>;
> };
> };
> };
>
> gic: fragment@1 {
> target-path = "/soc@...00000/interrupt-controller@...81000";
> __overlay__ {
> };
> };
> };
>
^ This is not going to work: You need the reference to the real gic not the empty fragment
here that has a target there.
You need to compile with the correct dtc, and you also need to compile the base dts
with dtc too, using the -@ flag. You can hack around it by adding something like
__symbols__ {
gic = "/soc@...00000/interrupt-controller@...81000”;
};
But you really need the __symbols__ node of the base dts generated by the dtc proper cause
the above is a dirty hack.
> And this is what Linux detects on that PCI bus:
>
> 00:0f.0 RAM memory: Red Hat, Inc Inter-VM shared memory
> Subsystem: Red Hat, Inc Inter-VM shared memory
> Control: I/O- Mem+ BusMaster- SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
> Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
> Interrupt: pin A routed to IRQ 17
> Region 0: Memory at 10000000 (64-bit, non-prefetchable) [size=256]
> Region 4: Memory at 10000100 (64-bit, non-prefetchable) [size=32]
> Kernel modules: ivshmem_net
>
> However, registering a handler on IRQ 17 fails (-EINVAL).
>
>
> With your dtc [2] (dtc -@ -I dts -O dtb -o vpci-bpi.dtb vpci-bpi.dts)
> and this fragment, I'm still not able to load the blob:
>
> /dts-v1/;
> /plugin/;
> / {
> compatible = "lemaker,bananapi", "allwinner,sun7i-a20";
>
> fragment@0 {
> target-path = "/soc@...00000";
> __overlay__ {
> #address-cells = <2>;
> #size-cells = <2>;
>
> vpci@...0000 {
> compatible = "pci-host-ecam-generic";
> device_type = "pci";
> bus-range = <0 0>;
> #address-cells = <3>;
> #size-cells = <2>;
> #interrupt-cells = <1>;
> interrupt-map-mask = <0 0 0 7>;
> interrupt-map = <0 0 0 1 &gic 0 0 0 123 4>,
> <0 0 0 2 &gic 0 0 0 124 4>,
> <0 0 0 3 &gic 0 0 0 125 4>,
> <0 0 0 4 &gic 0 0 0 126 4>;
> reg = <0 0x2000000 0 0x100000>;
> ranges =
> <0x02000000 0x00 0x10000000 0x00 0x10000000 0x00 0x30000000>;
> };
> };
> };
> };
>
Please try this branch of dtc; it’s a wip of what I’m trying to push to upstream.
https://github.com/pantoniou/dtc/tree/dgibson-overlay-panto
> Any suggestions? Any patches I'm missing in upstream to make that work?
>
> Jan
>
Regards
— Pantelis
> [1] https://github.com/pantoniou/linux-beagle-track-mainline/commit/160e68ec89eca33e8ed0abb13d52c07c54d7fc10
> [2] https://github.com/pantoniou/dtc/tree/dgibson-overlay-panto
>
> --
> Siemens AG, Corporate Technology, CT RDA ITP SES-DE
> Corporate Competence Center Embedded Linux
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