[PATCH v8 3/9] pci: Introduce pci_register_io_range() helper function.

Arnd Bergmann
2014-07-01T19:36:10Z

On Tuesday 01 July 2014 19:43:28 Liviu Dudau wrote:
> +/*
> + * Record the PCI IO range (expressed as CPU physical address + size).
> + * Return a negative value if an error has occured, zero otherwise
> + */
> +int __weak pci_register_io_range(phys_addr_t addr, resource_size_t size)
> +{
> +#ifdef PCI_IOBASE
> + struct io_range *res;
> + resource_size_t allocated_size = 0;
> +
> + /* check if the range hasn't been previously recorded */
> + list_for_each_entry(res, &io_range_list, list) {
> + if (addr >= res->start && addr + size <= res->start + size)
> + return 0;
> + allocated_size += res->size;
> + }
> +
> + /* range not registed yet, check for available space */
> + if (allocated_size + size - 1 > IO_SPACE_LIMIT)
> + return -E2BIG;
> +
> + /* add the range to the list */
> + res = kzalloc(sizeof(*res), GFP_KERNEL);
> + if (!res)
> + return -ENOMEM;
> +
> + res->start = addr;
> + res->size = size;
> +
> + list_add_tail(&res->list, &io_range_list);
> +
> + return 0;
> +#else
> + return -EINVAL;
> +#endif
> +}
> +
> unsigned long __weak pci_address_to_pio(phys_addr_t address)
> {
> +#ifdef PCI_IOBASE
> + struct io_range *res;
> + resource_size_t offset = 0;
> +
> + list_for_each_entry(res, &io_range_list, list) {
> + if (address >= res->start &&
> + address < res->start + res->size) {
> + return res->start - address + offset;
> + }
> + offset += res->size;
> + }
> +
> + return (unsigned long)-1;
> +#else
> if (address > IO_SPACE_LIMIT)
> return (unsigned long)-1;
>
> return (unsigned long) address;
> +#endif
> }

This still conflicts with the other allocator you have in patch 9
for pci_remap_iospace: nothing guarantees that the mapping is the
same for both.

Also, this is a completely pointless exercise at this moment, because
nobody cares about the result of pci_address_to_pio on architectures
that don't already provide this function. If we ever get a proper
Open Firmware implementation that wants to put hardcoded PCI devices
into DT, we can add an implementation, but for now this seems overkill.

The allocator in pci_register_io_range seems reasonable, why not merge
this function with pci_remap_iospace() as I have asked you multiple
times before? Just make it return the io_offset so the caller can
put that into the PCI host resources.

Arnd