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

[Liviu Dudau]

On Tue, Jul 08, 2014 at 02:01:04AM +0100, Bjorn Helgaas wrote:
> 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.
> >
> > Signed-off-by: Liviu Dudau <Liviu.Dudau@xxxxxxx>
> > Tested-by: Tanmay Inamdar <tinamdar@xxxxxxx>
> > ---
> >  drivers/of/of_pci.c       | 135 ++++++++++++++++++++++++++++++++++++++++++++++
> >  drivers/pci/host-bridge.c |  18 +++++++
> >  include/linux/of_pci.h    |  10 ++++
> >  include/linux/pci.h       |   8 +++
> >  4 files changed, 171 insertions(+)
> >
> > diff --git a/drivers/of/of_pci.c b/drivers/of/of_pci.c
> > index 8481996..55d8320 100644
> > --- a/drivers/of/of_pci.c
> > +++ b/drivers/of/of_pci.c
> > @@ -89,6 +89,141 @@ int of_pci_parse_bus_range(struct device_node *node, struct resource *res)
> >  }
> >  EXPORT_SYMBOL_GPL(of_pci_parse_bus_range);
> >
> > +/**
> > + * pci_host_bridge_of_get_ranges - Parse PCI host bridge resources from DT
> > + * @dev: device node of the host bridge having the range property
> > + * @resources: list where the range of resources will be added after DT parsing
> > + * @io_base: pointer to a variable that will contain the physical address for
> > + * the start of the I/O range.
> > + *
> > + * It is the callers job to free the @resources list if an error is returned.
> > + *
> > + * 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.
> > + *
> > + * Each architecture is then offered the chance of applying their own
> > + * filtering of pci_host_bridge_windows based on their own restrictions by
> > + * calling pcibios_fixup_bridge_ranges(). The filtered list of windows
> > + * can then be used when creating a pci_host_bridge structure.
> > + */
> > +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 you're not trying to match other printk formats, you could try to match
> the %pR format used elsewhere, e.g., "%#010llx-%#010llx" with
> range.cpu_addr, range.cpu_addr + range.size - 1.

Yes, not a big fan of the ugly output it generates, but the output matches closely the ranges
definition in the device tree file so it is easy to validate that you are parsing the right
entry. I am happy to change it to shorten the cpu range message.

> 
> > +
> > +             /*
> > +              * 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);
> > +     }
> > +
> > +     /* Apply architecture specific fixups for the ranges */
> > +     return pcibios_fixup_bridge_ranges(resources);
> > +}
> > +
> > +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;
> 
> If you put the dev_info() down here, you can print &bus_range with %pR.

Sure, will do.

> 
> > +     }
> > +     busno = bus_range->start;
> > +     pci_add_resource(&res, bus_range);
> > +
> > +     /* now parse the rest of host bridge bus ranges */
> > +     err = pci_host_bridge_of_get_ranges(parent->of_node, &res, &io_base);
> > +     if (err)
> > +             goto err_create;
> > +
> > +     /* then create the root bus */
> > +     root_bus = pci_create_root_bus_in_domain(parent, domain, busno,
> > +                                             ops, host_data, &res);
> > +     if (IS_ERR(root_bus)) {
> > +             err = PTR_ERR(root_bus);
> > +             goto err_create;
> > +     }
> > +
> > +     bridge = to_pci_host_bridge(root_bus->bridge);
> > +     bridge->io_base = io_base;
> > +
> > +     return bridge;
> > +
> > +err_create:
> > +     pci_free_resource_list(&res);
> > +     return ERR_PTR(err);
> > +}
> > +EXPORT_SYMBOL_GPL(of_create_pci_host_bridge);
> > +
> >  #ifdef CONFIG_PCI_MSI
> >
> >  static LIST_HEAD(of_pci_msi_chip_list);
> > diff --git a/drivers/pci/host-bridge.c b/drivers/pci/host-bridge.c
> > index 36c669e..cfee5d1 100644
> > --- a/drivers/pci/host-bridge.c
> > +++ b/drivers/pci/host-bridge.c
> > @@ -5,6 +5,9 @@
> >  #include <linux/kernel.h>
> >  #include <linux/pci.h>
> >  #include <linux/module.h>
> > +#include <linux/of_address.h>
> > +#include <linux/of_pci.h>
> > +#include <linux/slab.h>
> >
> >  #include "pci.h"
> >
> > @@ -83,3 +86,18 @@ void pcibios_bus_to_resource(struct pci_bus *bus, struct resource *res,
> >       res->end = region->end + offset;
> >  }
> >  EXPORT_SYMBOL(pcibios_bus_to_resource);
> > +
> > +/**
> > + * Simple version of the platform specific code for filtering the list
> > + * of resources obtained from the ranges declaration in DT.
> > + *
> > + * Platforms can override this function in order to impose stronger
> > + * constraints onto the list of resources that a host bridge can use.
> > + * The filtered list will then be used to create a root bus and associate
> > + * it with the host bridge.
> > + *
> > + */
> > +int __weak pcibios_fixup_bridge_ranges(struct list_head *resources)
> > +{
> > +     return 0;
> > +}
> 
> I'd wait to add this until there's a platform that needs to implement it.
> Splitting it out will make this patch that much smaller and easier to
> understand.

I need this as this is the default implementation (i.e. do nothing). Otherwise the
link phase will give errors. 

> 
> > diff --git a/include/linux/of_pci.h b/include/linux/of_pci.h
> > index dde3a4a..71e36d0 100644
> > --- a/include/linux/of_pci.h
> > +++ b/include/linux/of_pci.h
> > @@ -15,6 +15,9 @@ struct device_node *of_pci_find_child_device(struct device_node *parent,
> >  int of_pci_get_devfn(struct device_node *np);
> >  int of_irq_parse_and_map_pci(const struct pci_dev *dev, u8 slot, u8 pin);
> >  int of_pci_parse_bus_range(struct device_node *node, struct resource *res);
> > +struct pci_host_bridge *of_create_pci_host_bridge(struct device *parent,
> > +                                     struct pci_ops *ops, void *host_data);
> > +
> >  #else
> >  static inline int of_irq_parse_pci(const struct pci_dev *pdev, struct of_phandle_args *out_irq)
> >  {
> > @@ -43,6 +46,13 @@ of_pci_parse_bus_range(struct device_node *node, struct resource *res)
> >  {
> >       return -EINVAL;
> >  }
> > +
> > +static inline struct pci_host_bridge *
> > +of_create_pci_host_bridge(struct device *parent, struct pci_ops *ops,
> > +                     void *host_data)
> > +{
> > +     return NULL;
> > +}
> >  #endif
> >
> >  #if defined(CONFIG_OF) && defined(CONFIG_PCI_MSI)
> > diff --git a/include/linux/pci.h b/include/linux/pci.h
> > index 7e7b939..556dc5f 100644
> > --- a/include/linux/pci.h
> > +++ b/include/linux/pci.h
> > @@ -402,6 +402,7 @@ struct pci_host_bridge {
> >       struct device dev;
> >       struct pci_bus *bus;            /* root bus */
> >       int domain_nr;
> > +     resource_size_t io_base;        /* physical address for the start of I/O area */
> 
> I don't see where this is used yet.

It's used in pci_host_bridge_of_get_ranges() (earlier in this patch).

> 
> As far as I know, there's nothing that prevents a host bridge from having
> several I/O port apertures (or several memory-mapped I/O port spaces).

The pci_register_io_range() will give different offsets for each apperture.
I just need to make sure I don't overwrite io_base when parsing multiple IO
ranges.

Thanks for reviewing this,
Liviu

> 
> >       struct list_head windows;       /* pci_host_bridge_windows */
> >       void (*release_fn)(struct pci_host_bridge *);
> >       void *release_data;
> > @@ -1809,8 +1810,15 @@ static inline void pci_set_of_node(struct pci_dev *dev) { }
> >  static inline void pci_release_of_node(struct pci_dev *dev) { }
> >  static inline void pci_set_bus_of_node(struct pci_bus *bus) { }
> >  static inline void pci_release_bus_of_node(struct pci_bus *bus) { }
> > +
> >  #endif  /* CONFIG_OF */
> >
> > +/* Used by architecture code to apply any quirks to the list of
> > + * pci_host_bridge resource ranges before they are being used
> > + * by of_create_pci_host_bridge()
> > + */
> > +extern int pcibios_fixup_bridge_ranges(struct list_head *resources);
> > +
> >  #ifdef CONFIG_EEH
> >  static inline struct eeh_dev *pci_dev_to_eeh_dev(struct pci_dev *pdev)
> >  {
> > --
> > 2.0.0
> >
> 

-- 
====================
| I would like to |
| fix the world,  |
| but they're not |
| giving me the   |
 \ source code!  /
  ---------------
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