Mailing List Archive: Does xen has driver for i2c / spi / gpio pin ?

Does xen has driver for i2c / spi / gpio pin ?

Aug 5, 2020, 7:05 AM

Post #1 of 4 (283 views)

Hi All ,

With pointer from community i am able to find driver implementation
for backend / frontend.

But in Linux code base :

1) I can find backend for only pci / net / block .
Does XEN doesn't have drivers for i2c / spi / gpio etc.

2) If we need to have an xen driver only to handle gpio as an interrupt ,
what sections / driver will be required .
( In Linux an character driver with interrupt would be fine )

3) Is there any rules to decide if the device is supported or not by xen ?
In Linux we could find if there is an specific controller driver .
Assuming i I have two network controller IP from say different vendor
,
how to confirm which one will be supported by XEN ?

4) How to confirm if some custom IP core is supply by xen ?
( Say a soc has new IP core for new functionality , how can we confirm
if it will work in XEN (

Apologies if the question are too obvious , but since I am starting with
XEN
I am trying to understand ( & relate with Linux code base )

Request community members to please help on these as I was finding
difficult to
understand basic architecture here.

Thanks ,
Ashish

Re: Does xen has driver for i2c / spi / gpio pin ? [ In reply to ]

ashish.emailaddress at gmail

Aug 6, 2020, 12:21 AM

Post #2 of 4 (283 views)

Permalink

Hi Memebers ,

Any input on same or any pointers to some doc or wiki will be helpful

Thanks
Ashish

Re: Does xen has driver for i2c / spi / gpio pin ? [ In reply to ]

srn at prgmr

Aug 7, 2020, 3:18 PM

Post #3 of 4 (283 views)

Permalink

On 8/5/20 7:05 AM, AshishKumar Mishra wrote:
> Hi All ,
>
> With pointer from community i am able to find driver implementation
> for backend / frontend.
>
> But in Linux code base :
>
> 1) I can find backend for only pci / net / block .
> Does XEN doesn't have drivers for i2c / spi / gpio etc.
>
> 2) If we need to have an xen driver only to handle gpio as an interrupt ,
> what sections / driver will be required .
> ( In Linux an character driver with interrupt would be fine )
>
> 3) Is there any rules to decide if the device is supported or not by xen ?
> In Linux we could find if there is an specific controller driver .
> Assuming i I have two network controller IP from say different vendor
> ,
> how to confirm which one will be supported by XEN ?
>
> 4) How to confirm if some custom IP core is supply by xen ?
> ( Say a soc has new IP core for new functionality , how can we confirm
> if it will work in XEN (
>
>
> Apologies if the question are too obvious , but since I am starting with
> XEN
> I am trying to understand ( & relate with Linux code base )

In Xen, there's typically one or more domains that have at least some hardware drivers. Traditionally the "dom0" is the only domain with access to
hardware, though there are also driver domains https://wiki.xenproject.org/wiki/Driver_Domain. Then there are unprivileged guest domains that do not
talk directly to hardware.

The drivers you're talking about in 1) are to provide a paravirtualized interface to the unprivileged guest domains. See
https://wiki.xenproject.org/wiki/Xen_Networking for an example.

The dom0 is the default privileged domain. Otherwise, this may help explain how to pass through hardware to other domains that are not the dom0:

https://xenbits.xen.org/docs/4.14-testing/misc/arm/passthrough.txt

If you only need to control hardware without sharing it between domains, well-behaved drivers should Just Work. If instead you need shared use of a
resource that doesn't already have a paravirtualized driver, I would probably look at doing something custom via
https://xenbits.xen.org/docs/4.14-testing/man/xen-pv-channel.7.html or the under documented https://www.cs.uic.edu/~xzhang/vchan/

--Sarah

Re: Does xen has driver for i2c / spi / gpio pin ? [ In reply to ]

ashish.emailaddress at gmail

Aug 8, 2020, 9:11 AM

Post #4 of 4 (283 views)

Permalink

Hi Sarah ,

Thanks a lot for these details & links .

- Ashish

On Sat, 8 Aug, 2020, 3:48 AM Sarah Newman, <srn@prgmr.com> wrote:

> On 8/5/20 7:05 AM, AshishKumar Mishra wrote:
> > Hi All ,
> >
> > With pointer from community i am able to find driver implementation
> > for backend / frontend.
> >
> > But in Linux code base :
> >
> > 1) I can find backend for only pci / net / block .
> > Does XEN doesn't have drivers for i2c / spi / gpio etc.
> >
> > 2) If we need to have an xen driver only to handle gpio as an interrupt ,
> > what sections / driver will be required .
> > ( In Linux an character driver with interrupt would be fine )
> >
> > 3) Is there any rules to decide if the device is supported or not by
> xen ?
> > In Linux we could find if there is an specific controller driver .
> > Assuming i I have two network controller IP from say different
> vendor
> > ,
> > how to confirm which one will be supported by XEN ?
> >
> > 4) How to confirm if some custom IP core is supply by xen ?
> > ( Say a soc has new IP core for new functionality , how can we
> confirm
> > if it will work in XEN (
> >
> >
> > Apologies if the question are too obvious , but since I am starting with
> > XEN
> > I am trying to understand ( & relate with Linux code base )
>
>
> In Xen, there's typically one or more domains that have at least some
> hardware drivers. Traditionally the "dom0" is the only domain with access
> to
> hardware, though there are also driver domains
> https://wiki.xenproject.org/wiki/Driver_Domain. Then there are
> unprivileged guest domains that do not
> talk directly to hardware.
>
> The drivers you're talking about in 1) are to provide a paravirtualized
> interface to the unprivileged guest domains. See
> https://wiki.xenproject.org/wiki/Xen_Networking for an example.
>
> The dom0 is the default privileged domain. Otherwise, this may help
> explain how to pass through hardware to other domains that are not the dom0:
>
> https://xenbits.xen.org/docs/4.14-testing/misc/arm/passthrough.txt
>
> If you only need to control hardware without sharing it between domains,
> well-behaved drivers should Just Work. If instead you need shared use of a
> resource that doesn't already have a paravirtualized driver, I would
> probably look at doing something custom via
> https://xenbits.xen.org/docs/4.14-testing/man/xen-pv-channel.7.html or
> the under documented https://www.cs.uic.edu/~xzhang/vchan/
>
> --Sarah
>