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SubjectRe: [PATCH v10 08/10] OF: PCI: Add support for parsing PCI host bridge resources from DT
On Wed, Sep 10, 2014 at 03:22:41PM +0100, Liviu Dudau wrote:
> On Tue, Sep 09, 2014 at 02:35:46PM +0100, Lorenzo Pieralisi wrote:
> > On Mon, Sep 08, 2014 at 02:54:30PM +0100, Liviu Dudau wrote:
> > > Provide a function to parse the PCI DT ranges that can be used to
> > > create a pci_host_bridge structure together with its associated
> > > bus.
> > >
> > > Cc: Bjorn Helgaas <bhelgaas@google.com>
> > > Cc: Arnd Bergmann <arnd@arndb.de>
> > > Cc: Grant Likely <grant.likely@linaro.org>
> > > Cc: Rob Herring <robh+dt@kernel.org>
> > > Cc: Catalin Marinas <catalin.marinas@arm.com>
> > > Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
> > > ---
> > > drivers/of/of_pci.c | 102 +++++++++++++++++++++++++++++++++++++++++++++++++
> > > include/linux/of_pci.h | 11 ++++++
> > > 2 files changed, 113 insertions(+)
> > >
> > > diff --git a/drivers/of/of_pci.c b/drivers/of/of_pci.c
> > > index a107edb..36701da 100644
> > > --- a/drivers/of/of_pci.c
> > > +++ b/drivers/of/of_pci.c
> > > @@ -1,7 +1,9 @@
> > > #include <linux/kernel.h>
> > > #include <linux/export.h>
> > > #include <linux/of.h>
> > > +#include <linux/of_address.h>
> > > #include <linux/of_pci.h>
> > > +#include <linux/slab.h>
> > >
> > > static inline int __of_pci_pci_compare(struct device_node *node,
> > > unsigned int data)
> > > @@ -123,6 +125,106 @@ int of_pci_get_domain_nr(struct device_node *node, bool allocate_if_missing)
> > > }
> > > EXPORT_SYMBOL_GPL(of_pci_get_domain_nr);
> > >
> > > +/**
> > > + * of_pci_get_host_bridge_resources - Parse PCI host bridge resources from DT
> > > + * @dev: device node of the host bridge having the range property
> > > + * @busno: bus number associated with the bridge root bus
> > > + * @bus_max: maximum number of busses for this bridge
> > > + * @resources: list where the range of resources will be added after DT parsing
> > > + * @io_base: pointer to a variable that will contain on return the physical
> > > + * address for the start of the I/O range.
> > > + *
> > > + * It is the callers job to free the @resources list.
> > > + *
> > > + * This function will parse the "ranges" property of a PCI host bridge device
> > > + * node and setup the resource mapping based on its content. It is expected
> > > + * that the property conforms with the Power ePAPR document.
> >
> > You should also define what it returns and when.
>
> Thanks, will do.
>
> >
> > > + *
> > > + */
> > > +int of_pci_get_host_bridge_resources(struct device_node *dev,
> > > + unsigned char busno, unsigned char bus_max,
> > > + struct list_head *resources, resource_size_t *io_base)
> > > +{
> > > + struct resource *res;
> > > + struct resource *bus_range;
> > > + struct of_pci_range range;
> > > + struct of_pci_range_parser parser;
> > > + char range_type[4];
> > > + int err;
> > > +
> > > + bus_range = kzalloc(sizeof(*bus_range), GFP_KERNEL);
> > > + if (!bus_range)
> > > + return -ENOMEM;
> > > +
> > > + pr_info("PCI host bridge %s ranges:\n", dev->full_name);
> > > +
> > > + err = of_pci_parse_bus_range(dev, bus_range);
> > > + if (err) {
> > > + bus_range->start = busno;
> > > + bus_range->end = bus_max;
> > > + bus_range->flags = IORESOURCE_BUS;
> > > + pr_info(" No bus range found for %s, using %pR\n",
> > > + dev->full_name, &bus_range);
> > > + } else {
> > > + if (bus_range->end > bus_range->start + bus_max)
> > > + bus_range->end = bus_range->start + bus_max;
> > > + }
> > > + pci_add_resource(resources, bus_range);
> >
> > This means that eg in the PCI generic host controller I cannot "filter"
> > the bus resource, unless I remove it, "filter" it, and add it again.
>
> I'm not sure what you mean. Why do you have to remove the bus resource and
> add it again? What you get back from of_pci_get_host_bridge_resources() is
> a list of resources as they have been parsed from DT. You now have the option
> of doing any filtering that you might have done pre-v10 in the
> pcibios_fixup_bridge_ranges() but that is only on the list that was returned
> from of_pci_get_host_bridge_resources(). At this moment no root bus or
> host bridge structure has been created so no resource was added to those.
> With the filtered list you can use it to call pci_scan_root_bus() and *then*
> it gets added to the pci_host_bridge structure.

You are right sorry. As discussed, I just have to remove the resources
assignment in the respective host controller drivers (because you do
that in the API) and grab the resource pointers to "filter" them.

> > I certainly can't filter a resource that has been already added without
> > removing it first.
> >
> > Thoughts ?
>
> Hope I have explained what happens. Please let me know if you have any other
> comments.

There were other comments below ;)

Thanks,
Lorenzo

>
> Best regards,
> Liviu
>
> >
> > > +
> > > + /* Check for ranges property */
> > > + err = of_pci_range_parser_init(&parser, dev);
> > > + if (err)
> > > + goto parse_failed;
> > > +
> > > + pr_debug("Parsing ranges property...\n");
> > > + for_each_of_pci_range(&parser, &range) {
> > > + /* Read next ranges element */
> > > + if ((range.flags & IORESOURCE_TYPE_BITS) == IORESOURCE_IO)
> > > + snprintf(range_type, 4, " IO");
> > > + else if ((range.flags & IORESOURCE_TYPE_BITS) == IORESOURCE_MEM)
> > > + snprintf(range_type, 4, "MEM");
> > > + else
> > > + snprintf(range_type, 4, "err");
> > > + pr_info(" %s %#010llx..%#010llx -> %#010llx\n", range_type,
> > > + range.cpu_addr, range.cpu_addr + range.size - 1,
> > > + range.pci_addr);
> > > +
> > > + /*
> > > + * 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) {
> > > + err = -ENOMEM;
> > > + goto parse_failed;
> > > + }
> > > +
> > > + err = of_pci_range_to_resource(&range, dev, res);
> > > + if (err) {
> > > + kfree(res);
> >
> > You might want to add a label to free res to make things more uniform.
> >
> > > + goto parse_failed;
> > > + }
> > > +
> > > + if (resource_type(res) == IORESOURCE_IO) {
> > > + if (*io_base)
> >
> > You do not zero io_base in the first place so you should ask the API
> > user to do that. Is 0 a valid value BTW ? If it is you've got to resort
> > to something else to detect multiple IO resources.
> >
> > Lorenzo
>
> --
> ====================
> | I would like to |
> | fix the world, |
> | but they're not |
> | giving me the |
> \ source code! /
> ---------------
> ?\_(?)_/?



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