On Tue, May 10, 2016 at 8:49 PM, Tomasz Nowicki tn@semihalf.com wrote:
This patch is going to implement generic PCI host controller for ACPI world, similar to what pci-host-generic.c driver does for DT world.
All such drivers, which we have seen so far, were implemented within arch/ directory since they had some arch assumptions (x86 and ia64). However, they all are doing similar thing, so it makes sense to find some common code and abstract it into the generic driver.
In order to handle PCI config space regions properly, we define new MCFG interface which does sanity checks on MCFG table and keeps its root pointer. User is able to lookup MCFG regions based on that root pointer and specified domain:bus_start:bus_end touple. We are using pci_mmcfg_late_init old prototype to avoid another function name.
The implementation of pci_acpi_scan_root() looks up the MCFG entries and sets up a new mapping (regions are not mapped until host controller ask for it). Generic PCI functions are used for accessing config space. Driver selects PCI_ECAM and uses functions from drivers/pci/ecam.h to create and access ECAM mappings.
As mentioned in Kconfig help section, ACPI_PCI_HOST_GENERIC choice should be made on a per-architecture basis.
Signed-off-by: Tomasz Nowicki tn@semihalf.com Signed-off-by: Jayachandran C jchandra@broadcom.com
[....]
diff --git a/drivers/pci/ecam.h b/drivers/pci/ecam.h index 1ad2176..1cccf57 100644 --- a/drivers/pci/ecam.h +++ b/drivers/pci/ecam.h @@ -45,6 +45,11 @@ struct pci_config_window { void __iomem *win; /* 64-bit single mapping */ void __iomem **winp; /* 32-bit per bus mapping */ }; +#ifdef CONFIG_ACPI_PCI_HOST_GENERIC
struct acpi_device *companion; /* ACPI companion device */+#endif
int domain;};
Using struct pci_config_window to pass along domain and companion looks bad. I think there are two possible options to do this better:
1. add a 'struct fwnode_handle *' or 'struct device *parent_dev' instead of the companion and domain fields above. In case of ACPI either of them can be used to get the acpi_device and both domain and companion can be set from that.
2. make pci_config_window fully embeddable by moving allocation out of pci_ecam_create to its callers. Then it can be embedded into acpi_pci_generic_root_info, and container_of can be used to get acpi info from ->sysdata.
The first option should be easier to implement but the second may be better on long run. I would leave it to the Bjorn or Rafael to suggest which is preferred.
JC.