[PATCH v8 8/9] pci: Add support for creating a generic host_bridge from device tree

Will Deacon
2014-07-02T11:22:30Z

Hi Liviu,

On Tue, Jul 01, 2014 at 07:43:33PM +0100, Liviu Dudau wrote:
> Several platforms use a rather generic version of parsing
> the device tree to find the host bridge ranges. Move the common code
> into the generic PCI code and use it to create a pci_host_bridge
> structure that can be used by arch code.
>
> Based on early attempts by Andrew Murray to unify the code.
> Used powerpc and microblaze PCI code as starting point.

I just had a quick look at this to see how it differs from the parsing in
pci-host-generic.c and there a few small differences worth discussing.

> +static int pci_host_bridge_of_get_ranges(struct device_node *dev,
> + struct list_head *resources, resource_size_t *io_base)
> +{
> + struct resource *res;
> + struct of_pci_range range;
> + struct of_pci_range_parser parser;
> + int err;
> +
> + pr_info("PCI host bridge %s ranges:\n", dev->full_name);
> +
> + /* Check for ranges property */
> + err = of_pci_range_parser_init(&parser, dev);
> + if (err)
> + return err;
> +
> + pr_debug("Parsing ranges property...\n");
> + for_each_of_pci_range(&parser, &range) {
> + /* Read next ranges element */
> + pr_debug("pci_space: 0x%08x pci_addr:0x%016llx cpu_addr:0x%016llx size:0x%016llx\n",
> + range.pci_space, range.pci_addr, range.cpu_addr, range.size);
> +
> + /*
> + * If we failed translation or got a zero-sized region
> + * then skip this range
> + */
> + if (range.cpu_addr == OF_BAD_ADDR || range.size == 0)
> + continue;
> +
> + res = kzalloc(sizeof(struct resource), GFP_KERNEL);
> + if (!res)
> + return -ENOMEM;
> +
> + err = of_pci_range_to_resource(&range, dev, res);
> + if (err)
> + return err;
> +
> + if (resource_type(res) == IORESOURCE_IO)
> + *io_base = range.cpu_addr;
> +
> + pci_add_resource_offset(resources, res,
> + res->start - range.pci_addr);

Where do you request_resource before adding it?

> + }
> +
> + /* Apply architecture specific fixups for the ranges */
> + return pcibios_fixup_bridge_ranges(resources);

I currently mandate at least one non-prefetchable resource in the
device-tree. Should I simply drop this restriction, or do I have to somehow
hook this into the pcibios callback?

> +}
> +
> +static atomic_t domain_nr = ATOMIC_INIT(-1);
> +
> +/**
> + * of_create_pci_host_bridge - Create a PCI host bridge structure using
> + * information passed in the DT.
> + * @parent: device owning this host bridge
> + * @ops: pci_ops associated with the host controller
> + * @host_data: opaque data structure used by the host controller.
> + *
> + * returns a pointer to the newly created pci_host_bridge structure, or
> + * NULL if the call failed.
> + *
> + * This function will try to obtain the host bridge domain number by
> + * using of_alias_get_id() call with "pci-domain" as a stem. If that
> + * fails, a local allocator will be used that will put each host bridge
> + * in a new domain.
> + */
> +struct pci_host_bridge *
> +of_create_pci_host_bridge(struct device *parent, struct pci_ops *ops, void *host_data)
> +{
> + int err, domain, busno;
> + struct resource *bus_range;
> + struct pci_bus *root_bus;
> + struct pci_host_bridge *bridge;
> + resource_size_t io_base;
> + LIST_HEAD(res);
> +
> + bus_range = kzalloc(sizeof(*bus_range), GFP_KERNEL);
> + if (!bus_range)
> + return ERR_PTR(-ENOMEM);
> +
> + domain = of_alias_get_id(parent->of_node, "pci-domain");
> + if (domain == -ENODEV)
> + domain = atomic_inc_return(&domain_nr);
> +
> + err = of_pci_parse_bus_range(parent->of_node, bus_range);
> + if (err) {
> + dev_info(parent, "No bus range for %s, using default [0-255]\n",
> + parent->of_node->full_name);
> + bus_range->start = 0;
> + bus_range->end = 255;
> + bus_range->flags = IORESOURCE_BUS;

What about bus_range->name?

> + }
> + busno = bus_range->start;
> + pci_add_resource(&res, bus_range);

I currently truncate the bus range to fit inside the Configuration Space
window I have (in the reg property). How can I continue to do that with this
patch?

Will