[Xenomai-help] Mem mapped i/o in RTDM driver

[Xenomai-help] Mem mapped i/o in RTDM driver

[jeff angielski]

A basic RTDM question:

In a normal Linux device driver you typically use request_mem_region()
and ioremap_nocache() to setup access to some memory mapped i/o.  Then
you just iowrite()/ioread() to/from that address.

Do I still do this for the XXXXX_nrt operations in my RTDM driver?

How about for the XXXX_rt operations?  

I do see that gpioirqbench uses the Linux memory management indirectly
since it relies on the OF mpc52xx_find_and_map("mpc5200-gpio") but
because the driver supports both Linux and RTDM, the requirements are
not clear.

Thanks.


-- 
Jeff Angielski
The PTR Group
www.theptrgroup.com

Re: [Xenomai-help] Mem mapped i/o in RTDM driver

[Philippe Gerum]

On Thu, 2009-04-23 at 14:55 -0400, jeff angielski wrote:
> A basic RTDM question:
> 
> In a normal Linux device driver you typically use request_mem_region()
> and ioremap_nocache() to setup access to some memory mapped i/o.  Then
> you just iowrite()/ioread() to/from that address.
> 
> Do I still do this for the XXXXX_nrt operations in my RTDM driver?

Yes.

> 
> How about for the XXXX_rt operations?  
> 

ioread/iowrite will be usable the same way, but you will have to
ioremap() in a non RT context first.

> I do see that gpioirqbench uses the Linux memory management indirectly
> since it relies on the OF mpc52xx_find_and_map("mpc5200-gpio") but
> because the driver supports both Linux and RTDM, the requirements are
> not clear.

Care is taken to always refer to MPC52xx_GPIO from a plain Linux
context.

> 
> Thanks.
> 
> 
-- 
Philippe.

Re: [Xenomai-help] Mem mapped i/o in RTDM driver

[Philippe Gerum]

On Thu, 2009-04-23 at 14:55 -0400, jeff angielski wrote:
> A basic RTDM question:
> 
> In a normal Linux device driver you typically use request_mem_region()
> and ioremap_nocache() to setup access to some memory mapped i/o.  Then
> you just iowrite()/ioread() to/from that address.

Btw, maybe readb/w/l() and writeb/w/l() are more appropriate since
ioread/write is a legacy interface?

> 
> Do I still do this for the XXXXX_nrt operations in my RTDM driver?
> 
> How about for the XXXX_rt operations?  
> 
> I do see that gpioirqbench uses the Linux memory management indirectly
> since it relies on the OF mpc52xx_find_and_map("mpc5200-gpio") but
> because the driver supports both Linux and RTDM, the requirements are
> not clear.
> 
> Thanks.
> 
> 
-- 
Philippe.

Re: [Xenomai-help] Mem mapped i/o in RTDM driver

[Philippe Gerum]

On Thu, 2009-04-30 at 15:48 +0200, Philippe Gerum wrote:
> On Thu, 2009-04-23 at 14:55 -0400, jeff angielski wrote:
> > A basic RTDM question:
> > 
> > In a normal Linux device driver you typically use request_mem_region()
> > and ioremap_nocache() to setup access to some memory mapped i/o.  Then
> > you just iowrite()/ioread() to/from that address.
> 
> Btw, maybe readb/w/l() and writeb/w/l() are more appropriate since
> ioread/write is a legacy interface?

i.e. in MMIO mode.

> 
> > 
> > Do I still do this for the XXXXX_nrt operations in my RTDM driver?
> > 
> > How about for the XXXX_rt operations?  
> > 
> > I do see that gpioirqbench uses the Linux memory management indirectly
> > since it relies on the OF mpc52xx_find_and_map("mpc5200-gpio") but
> > because the driver supports both Linux and RTDM, the requirements are
> > not clear.
> > 
> > Thanks.
> > 
> > 
-- 
Philippe.