Re: [PATCH v2 1/4] pci: OF: Fix the conversion of IO ranges into IO resources.

[Liviu Dudau]

On Thu, Feb 27, 2014 at 01:22:19PM +0000, Andrew Murray wrote:
> On 27 February 2014 13:06, Liviu Dudau <Liviu.Dudau@xxxxxxx> wrote:
> >
> > The ranges property for a host bridge controller in DT describes
> > the mapping between the PCI bus address and the CPU physical address.
> > The resources framework however expects that the IO resources start
> > at a pseudo "port" address 0 (zero) and have a maximum size of 64kb.
> 
> Is this just in the case of ARM? (I've tried to keep up with the
> conversation, but apologies if I've misunderstood).
> 
> > The conversion from pci ranges to resources failed to take that into
> > account.
> >
> > In the process move the function into drivers/of/address.c as it
> > now depends on pci_address_to_pio() code.
> >
> > Signed-off-by: Liviu Dudau <Liviu.Dudau@xxxxxxx>
> >
> > diff --git a/drivers/of/address.c b/drivers/of/address.c
> > index 1a54f1f..7cf2b16 100644
> > --- a/drivers/of/address.c
> > +++ b/drivers/of/address.c
> > @@ -719,3 +719,34 @@ void __iomem *of_iomap(struct device_node *np, int index)
> >         return ioremap(res.start, resource_size(&res));
> >  }
> >  EXPORT_SYMBOL(of_iomap);
> > +
> > +/**
> > + * of_pci_range_to_resource - Create a resource from an of_pci_range
> > + * @range:     the PCI range that describes the resource
> > + * @np:                device node where the range belongs to
> > + * @res:       pointer to a valid resource that will be updated to
> > + *              reflect the values contained in the range.
> > + * Note that if the range is an IO range, the resource will be converted
> > + * using pci_address_to_pio() which can fail if it is called to early or
> > + * if the range cannot be matched to any host bridge IO space.
> > + */
> > +void of_pci_range_to_resource(struct of_pci_range *range,
> > +       struct device_node *np, struct resource *res)
> > +{
> > +       res->flags = range->flags;
> > +       if (res->flags & IORESOURCE_IO) {
> > +               unsigned long port;
> > +               port = pci_address_to_pio(range->pci_addr);
> 
> Is this likely to break existing users of of_pci_range_to_resource?

I've tested the change with a tegra2 based device (trimslice) and I've
got a functional board.

> 
> For example arch/mips: IO_SPACE_LIMIT defaults to 0xffff and there is
> no overridden implementation for pci_address_to_pio, therefore this
> will set res->start to OF_BAD_ADDR whereas previously it would have
> been the CPU address for I/O (assuming the cpu_addr was previously >
> 64K).

And that is why I'm using pci_addr as the physical address passed to
pci_address_to_pio. My idea is that when converting ranges into resources,
for IORESOURCE_IO we should generate a resource that uses logical I/O
addresses, not physical CPU addresses. How we get that needs debating,
currently I've took the shortcut of using the pci_addr to get the port
number.

> 
> I have no idea if I/O previously worked for mips, but this patch seems
> to change that behavior. It may be a similar story for microblaze and
> powerpc.

Both microblaze and powerpc share an identical implementation and it is
expecting that the physical address passed as parameter fits between
io_base_phys and io_base_phys + pcibios_io_size(hose). So yes, the
correct way is to use cpu_addr and fix the weak implementation? But we
don't have enough information for the weak implementation to work, as
we don't know where the physical IO base start (we are just about to
find out from DT).

Thanks for reviewing these patches!

Liviu

> 
> Andrew Murray
> 
> > +               if (port == (unsigned long)-1) {
> > +                       res->start = (resource_size_t)OF_BAD_ADDR;
> > +                       res->end = (resource_size_t)OF_BAD_ADDR;
> > +                       return;
> > +               }
> > +               res->start = port;
> > +       } else {
> > +               res->start = range->cpu_addr;
> > +       }
> > +       res->end = res->start + range->size - 1;
> > +       res->parent = res->child = res->sibling = NULL;
> > +       res->name = np->full_name;
> > +}
> > diff --git a/include/linux/of_address.h b/include/linux/of_address.h
> > index 5f6ed6b..a667762 100644
> > --- a/include/linux/of_address.h
> > +++ b/include/linux/of_address.h
> > @@ -23,17 +23,8 @@ struct of_pci_range {
> >  #define for_each_of_pci_range(parser, range) \
> >         for (; of_pci_range_parser_one(parser, range);)
> >
> > -static inline void of_pci_range_to_resource(struct of_pci_range *range,
> > -                                           struct device_node *np,
> > -                                           struct resource *res)
> > -{
> > -       res->flags = range->flags;
> > -       res->start = range->cpu_addr;
> > -       res->end = range->cpu_addr + range->size - 1;
> > -       res->parent = res->child = res->sibling = NULL;
> > -       res->name = np->full_name;
> > -}
> > -
> > +extern void of_pci_range_to_resource(struct of_pci_range *range,
> > +               struct device_node *np, struct resource *res);
> >  /* Translate a DMA address from device space to CPU space */
> >  extern u64 of_translate_dma_address(struct device_node *dev,
> >                                     const __be32 *in_addr);
> > --
> > 1.9.0
> >
> > --
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> 

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