[PATCH v7 4/6] pci: Introduce a domain number for pci_host_bridge.

Liviu Dudau
2014-04-10T14:53:04Z

On Thu, Apr 10, 2014 at 03:07:44PM +0100, Arnd Bergmann wrote:
> On Thursday 10 April 2014 07:50:52 Bjorn Helgaas wrote:
> > On Thu, Apr 10, 2014 at 2:00 AM, Arnd Bergmann <arnd@arndb.de> wrote:
> > > On Wednesday 09 April 2014 21:48:14 Bjorn Helgaas wrote:
> > >> On Wed, Apr 9, 2014 at 7:27 PM, Liviu Dudau <liviu@dudau.co.uk> wrote:
> > >> > On Wed, Apr 09, 2014 at 08:02:41AM -0600, Bjorn Helgaas wrote:
> > >> >> >> struct pci_host_bridge {
> > >> >> >> int domain;
> > >> >> >> int node;
> > >> >> >> struct device *dev;
> > >> >> >> struct pci_ops *ops;
> > >> >> >> struct list_head resources;
> > >> >> >> void *sysdata;
> > >> >> >> struct pci_bus *bus; /* filled in by core, not by arch */
> > >> >> >> ... /* other existing contents managed by core */
> > >> >> >> };
> > >> >> >>
> > >> >> >> struct pci_bus *pci_scan_host_bridge(struct pci_host_bridge *bridge);
> > >> >> >
> >
> > I'm not sure I'm following you; you mean the arch-specific sysdata
> > structure would contain a pointer to struct pci_host_bridge?
> >
> > I have to admit that I'm not up on how other subsystems handle this
> > sort of abstraction. Do you have any pointers to good examples that I
> > can study?
>
> What I mean is like this:
>
> /* generic structure */
> struct pci_host_bridge {
> int domain;
> int node;
> struct device *dev;
> struct pci_ops *ops;
> struct list_head resources;
> struct pci_bus *bus; /* filled in by core, not by arch */
> ... /* other existing contents managed by core */
> };
>
> /* arm specific structure */
> struct pci_sys_data {
> char io_res_name[12];
> /* Bridge swizzling */
> u8 (*swizzle)(struct pci_dev *, u8 *);
> /* IRQ mapping */
> int (*map_irq)(const struct pci_dev *, u8, u8);
> /* Resource alignement requirements */
> void (*add_bus)(struct pci_bus *bus);
> void (*remove_bus)(struct pci_bus *bus);
> void *private_data; /* platform controller private data */
>
> /* not a pointer: */
> struct pci_host_bridge bridge;
> };
> static inline struct pci_sys_data *to_pci_sys_data(struct pci_host_bridge *bridge)
> {
> return container_of(bridge, struct pci_sys_data, bridge);
> }
>
> /* arm specific, driver specific structure */
> struct tegra_pcie {
> void __iomem *pads;
> void __iomem *afi;
>
> struct clk *pex_clk;
> struct clk *afi_clk;
> struct clk *pll_e;
> struct clk *cml_clk;
>
> struct tegra_msi msi;
>
> struct list_head ports;
> unsigned int num_ports;
>
> struct pci_sys_data sysdata;
> };
> static inline struct tegra_pcie *to_tegra_pcie(struct pci_sys_data *sysdata)
> {
> return container_of(sysdata, struct tegra_pcie, sysdata);
> }
>
> This mirrors how we treat devices: a pci_device has an embedded device,
> and so on, in other subsystems we can have multiple layers.
>
> In this example, the tegra pcie driver then allocates its own tegra_pcie
> structure, fills out the fields it needs, and registers it with the
> ARM architecture code, passing just the pci_sys_data pointer. That function
> in turn passes a pointer to the embedded pci_host_bridge down to the
> generic code. Ideally we should try to eliminate the architecture specific
> portion here, but that is a later step.

So Arnd seems to agree with me: we should try to get out of architecture specific
pci_sys_data and link the host bridge driver straight into the PCI core. The
core then can call into arch code via pcibios_*() functions.

Arnd, am I reading correctly into what you are saying?

Liviu

>
> Arnd
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>

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