On Thursday 10 April 2014 07:50:52 Bjorn Helgaas wrote: > On Thu, Apr 10, 2014 at 2:00 AM, Arnd Bergmann <arnd@xxxxxxxx> wrote: > > On Wednesday 09 April 2014 21:48:14 Bjorn Helgaas wrote: > >> On Wed, Apr 9, 2014 at 7:27 PM, Liviu Dudau <liviu@xxxxxxxxxxx> 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. Arnd -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html