This is v4 of my attempt to add support for a generic pci_host_bridge controller created from a description passed in the device tree.
Changes from v3: - Dynamically allocate bus_range resource in of_create_pci_host_bridge() - Fix the domain number used when creating child busses. - Changed domain number allocator to use atomic operations. - Use ERR_PTR() to propagate the error out of pci_create_root_bus_in_domain() and of_create_pci_host_bridge().
Changes from v2: - Use range->cpu_addr when calling pci_address_to_pio() - Introduce pci_register_io_range() helper function in order to register io ranges ahead of their conversion to PIO values. This is needed as no information is being stored yet regarding the range mapping, making pci_address_to_pio() fail. Default weak implementation does nothing, to cover the default weak implementation of pci_address_to_pio() that expects direct mapping of physical addresses into PIO values (x86 view).
Changes from v1: - Add patch to fix conversion of IO ranges into IO resources. - Added a domain_nr member to pci_host_bridge structure, and a new function to create a root bus in a given domain number. In order to facilitate that I propose changing the order of initialisation between pci_host_bridge and it's related bus in pci_create_root_bus() as sort of a rever of 7b5436635800. This is done in patch 1/4 and 2/4. - Added a simple allocator of domain numbers in drivers/pci/host-bridge.c. The code will first try to get a domain id from of_alias_get_id(..., "pci-domain") and if that fails assign the next unallocated domain id. - Changed the name of the function that creates the generic host bridge from pci_host_bridge_of_init to of_create_pci_host_bridge and exported as GPL symbol.
v1 thread here: https://lkml.org/lkml/2014/2/3/380
The following is an edit of the original blurb:
Following the discussion started here [1], I now have a proposal for tackling generic support for host bridges described via device tree. It is an initial stab at it, to try to get feedback and suggestions, but it is functional enough that I have PCI Express for arm64 working on an FPGA using the patch that I am also publishing that adds support for PCI for that platform.
Looking at the existing architectures that fit the requirements (use of device tree and PCI) yields the powerpc and microblaze as generic enough to make them candidates for conversion. I have a tentative patch for microblaze that I can only compile test it, unfortunately using qemu-microblaze leads to an early crash in the kernel.
As Bjorn has mentioned in the previous discussion, the idea is to add to struct pci_host_bridge enough data to be able to reduce the size or remove the architecture specific pci_controller structure. arm64 support actually manages to get rid of all the architecture static data and has no pci_controller structure defined. For host bridge drivers that means a change of API unless architectures decide to provide a compatibility layer (comments here please).
In order to initialise a host bridge with the new API, the following example code is sufficient for a _probe() function:
static int myhostbridge_probe(struct platform_device *pdev) { int err; struct device_node *dev; struct pci_host_bridge *bridge; struct myhostbridge_port *pp; resource_size_t lastbus;
dev = pdev->dev.of_node;
if (!of_device_is_available(dev)) { pr_warn("%s: disabled\n", dev->full_name); return -ENODEV; }
pp = kzalloc(sizeof(struct myhostbridge_port), GFP_KERNEL); if (!pp) return -ENOMEM;
bridge = of_create_pci_host_bridge(&pdev->dev, &myhostbridge_ops, pp); if (IS_ERR(bridge)) { err = PTR_ERR(bridge); goto bridge_create_fail; }
err = myhostbridge_setup(bridge->bus); if (err) goto bridge_setup_fail;
/* We always enable PCI domains and we keep domain 0 backward * compatible in /proc for video cards */ pci_add_flags(PCI_ENABLE_PROC_DOMAINS); pci_add_flags(PCI_REASSIGN_ALL_BUS | PCI_REASSIGN_ALL_RSRC);
lastbus = pci_scan_child_bus(bridge->bus); pci_bus_update_busn_res_end(bridge->bus, lastbus);
pci_assign_unassigned_bus_resources(bridge->bus);
pci_bus_add_devices(bridge->bus);
return 0;
bridge_setup_fail: put_device(&bridge->dev); device_unregister(&bridge->dev); bridge_create_fail: kfree(pp); return err; }
[1] http://thread.gmane.org/gmane.linux.kernel.pci/25946
Best regards, Liviu
Liviu Dudau (6): pci: Introduce pci_register_io_range() helper function. pci: OF: Fix the conversion of IO ranges into IO resources. pci: Create pci_host_bridge before its associated bus in pci_create_root_bus. pci: Introduce a domain number for pci_host_bridge. pci: Use parent domain number when allocating child busses. pci: Add support for creating a generic host_bridge from device tree
drivers/of/address.c | 39 +++++++++++++ drivers/pci/host-bridge.c | 139 +++++++++++++++++++++++++++++++++++++++++++++ drivers/pci/probe.c | 72 +++++++++++++++-------- include/linux/of_address.h | 14 +---- include/linux/pci.h | 17 ++++++ 5 files changed, 246 insertions(+), 35 deletions(-)