From 8bb705e3e79d84e77edd4499e74483dd96a4626c Mon Sep 17 00:00:00 2001 From: Christian König Date: Tue, 24 Oct 2017 14:40:26 -0500 Subject: PCI: Add pci_resize_resource() for resizing BARs MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add a pci_resize_resource() interface to allow device drivers to resize BARs of their devices. This is useful for devices with large local storage, e.g., graphics devices. These devices often only expose 256MB BARs initially to be compatible with 32-bit systems. This function only tries to reprogram the windows of the bridge directly above the requesting device and only the BAR of the same type (usually mem, 64bit, prefetchable). This is done to avoid disturbing other drivers by changing the BARs of their devices. Drivers should use the following sequence to resize their BARs: 1. Disable memory decoding of the device using the PCI cfg dword. 2. Use pci_release_resource() to release all BARs which can move during the resize, including the one you want to resize. 3. Call pci_resize_resource() for each BAR you want to resize. 4. Call pci_assign_unassigned_bus_resources() to reassign new locations for all BARs which are not resized, but could move. 5. If everything worked as expected, enable memory decoding in the device again using the PCI cfg dword. Signed-off-by: Christian König Signed-off-by: Bjorn Helgaas --- drivers/pci/setup-bus.c | 98 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 98 insertions(+) (limited to 'drivers/pci/setup-bus.c') diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c index 73dda0d59bbc..6826a893288a 100644 --- a/drivers/pci/setup-bus.c +++ b/drivers/pci/setup-bus.c @@ -1913,6 +1913,104 @@ enable_all: } EXPORT_SYMBOL_GPL(pci_assign_unassigned_bridge_resources); +int pci_reassign_bridge_resources(struct pci_dev *bridge, unsigned long type) +{ + struct pci_dev_resource *dev_res; + struct pci_dev *next; + LIST_HEAD(saved); + LIST_HEAD(added); + LIST_HEAD(failed); + unsigned int i; + int ret; + + /* Walk to the root hub, releasing bridge BARs when possible */ + next = bridge; + do { + bridge = next; + for (i = PCI_BRIDGE_RESOURCES; i < PCI_BRIDGE_RESOURCE_END; + i++) { + struct resource *res = &bridge->resource[i]; + + if ((res->flags ^ type) & PCI_RES_TYPE_MASK) + continue; + + /* Ignore BARs which are still in use */ + if (res->child) + continue; + + ret = add_to_list(&saved, bridge, res, 0, 0); + if (ret) + goto cleanup; + + dev_info(&bridge->dev, "BAR %d: releasing %pR\n", + i, res); + + if (res->parent) + release_resource(res); + res->start = 0; + res->end = 0; + break; + } + if (i == PCI_BRIDGE_RESOURCE_END) + break; + + next = bridge->bus ? bridge->bus->self : NULL; + } while (next); + + if (list_empty(&saved)) + return -ENOENT; + + __pci_bus_size_bridges(bridge->subordinate, &added); + __pci_bridge_assign_resources(bridge, &added, &failed); + BUG_ON(!list_empty(&added)); + + if (!list_empty(&failed)) { + ret = -ENOSPC; + goto cleanup; + } + + list_for_each_entry(dev_res, &saved, list) { + /* Skip the bridge we just assigned resources for. */ + if (bridge == dev_res->dev) + continue; + + bridge = dev_res->dev; + pci_setup_bridge(bridge->subordinate); + } + + free_list(&saved); + return 0; + +cleanup: + /* restore size and flags */ + list_for_each_entry(dev_res, &failed, list) { + struct resource *res = dev_res->res; + + res->start = dev_res->start; + res->end = dev_res->end; + res->flags = dev_res->flags; + } + free_list(&failed); + + /* Revert to the old configuration */ + list_for_each_entry(dev_res, &saved, list) { + struct resource *res = dev_res->res; + + bridge = dev_res->dev; + i = res - bridge->resource; + + res->start = dev_res->start; + res->end = dev_res->end; + res->flags = dev_res->flags; + + pci_claim_resource(bridge, i); + pci_setup_bridge(bridge->subordinate); + } + free_list(&saved); + + return ret; +} + void pci_assign_unassigned_bus_resources(struct pci_bus *bus) { struct pci_dev *dev; -- cgit v1.2.3