Re: PCIE: Program pcie device private registers

[Alex Williamson <alex.williamson@redhat.com>]

On Tue, 2014-03-04 at 10:45 -0700, Bjorn Helgaas wrote:
> On Mon, Mar 3, 2014 at 8:59 PM, Pratyush Anand <pratyush.anand@st.com> wrote:
> > On Thu, Feb 27, 2014 at 05:12:38PM +0800, shiv prakash Agarwal wrote:
> >>    Hi All,
> >>
> >>
> >>
> >>    One query:
> >>
> >>
> >>
> >>    We can program config space registers of a pcie device using setpci but
> >>    how can we program private registers of a pcie device?
> >
> > You mean application specific registers?
> > These registers will not be accessible through any generic user space program.
> >
> > If you want to access them for debug purposes then you can provide
> > support in your driver.
> 
> If the registers are in config space, you can use setpci, even if they
> are non-architected registers specific to the device.
> 
> If they are in MMIO space, you can use lspci to learn where the BARs
> are mapped, and then use something like rdwrmem
> (http://cmp.felk.cvut.cz/~pisa/linux/rdwrmem.c) to access the
> registers.
> 
> If they are in I/O port space, you can again use lspci to learn where
> they are mapped, and then use ioperm()/iopl()/inb()/outb()/etc.

The pci-sysfs resource# files are probably an easier alternative.  MMIO
regions can be mmap'd and I/O port regions support direct read/write.
Thanks,

Alex