Re: [PATCH V6 2/5] PCI: Adapt pci_register_io_range() for indirect-IO and PCI I/O translation

[John Garry]

On 31/01/2017 00:10, Bjorn Helgaas wrote:
> On Tue, Jan 24, 2017 at 03:05:22PM +0800, zhichang.yuan wrote:
> > After indirect-IO is introduced, system must can assigned indirect-IO devices
> > with logical I/O ranges which are different from those for PCI I/O devices.
> > Otherwise, I/O accessors can't identify whether the I/O port is for memory
> > mapped I/O or indirect-IO.
>
> Maybe:
>
>   We must assign logical I/O port space for indirect I/O such that the
>   I/O accessors can tell whether a logical I/O port refers to memory-
>   mapped I/O space or indirect I/O space.

It's better

> > As current helper, pci_register_io_range(), is used for PCI I/O ranges
> > registration and translation, indirect-IO devices should also apply these
> > helpers to manage the I/O ranges. It will be easy to ensure the assigned
> > logical I/O ranges unique.
> > But for indirect-IO devices, there is no cpu address. The current
> > pci_register_io_range() can not work for this case.
> >
> > This patch makes some changes on the pci_register_io_range() to support the
> > I/O range registration with device's fwnode also. After this, the indirect-IO
> > devices can register the device-local I/O range to system logical I/O and
> > easily perform the translation between device-local I/O range and sytem
> > logical I/O range.
>
> > -int __weak pci_register_io_range(phys_addr_t addr, resource_size_t size)
> > +int __weak pci_register_io_range(struct fwnode_handle *node, phys_addr_t addr,
> > +				 resource_size_t size, unsigned long *port)
>
> Why is this __weak?  It looks like it's been __weak since its
> introduction by 41f8bba7f555 ("of/pci: Add pci_register_io_range() and
> pci_pio_to_address()"), but I don't see any other implementations of
> it.
>
> Can you add a patch that does nothing but make this non-weak?

OK

> > +#else
> > +	/*
> > +	 * powerpc and microblaze have their own registration,
> > +	 * just look up the value here
>
> Can you include a pointer to the powerpc and microblaze registration
> code here?  It's conceivable that somebody could generalize this
> enough to support powerpc and microblaze as well.

It should be no problem

> > --- a/include/linux/pci.h
> > +++ b/include/linux/pci.h
> > @@ -34,6 +34,9 @@
> >
> >  #include <linux/pci_ids.h>
> >
> > +/* the macro below flags an invalid cpu address
> > + * and is used by IO special hosts              */
>
> s/cpu/CPU/

OK

> Use conventional multi-line comment style:
>
> /*
>  * IO_RANGE_IOEXT flags an invalid CPU address ...
>  */
>
> > +#define IO_RANGE_IOEXT (resource_size_t)(-1ull)
>
> And put this close to related things, e.g., pci_register_io_range(),
> instead of just dropping it in at the top of the file.

OK

> >  /*
> >   * The PCI interface treats multi-function devices as independent
> >   * devices.  The slot/function address of each device is encoded
> > @@ -1197,8 +1200,8 @@ int __must_check pci_bus_alloc_resource(struct pci_bus *bus,
> >  						  resource_size_t),
> >  			void *alignf_data);
> >
> > -
> > -int pci_register_io_range(phys_addr_t addr, resource_size_t size);
> > +int pci_register_io_range(struct fwnode_handle *node, phys_addr_t addr,
> > +			  resource_size_t size, unsigned long *port);
> >  unsigned long pci_address_to_pio(phys_addr_t addr);
> >  phys_addr_t pci_pio_to_address(unsigned long pio);
> >  int pci_remap_iospace(const struct resource *res, phys_addr_t phys_addr);
> > --
> > 1.9.1

Thanks,
John

> .