diff options
| -rw-r--r-- | src/device/pci_device.c | 63 |
1 files changed, 61 insertions, 2 deletions
diff --git a/src/device/pci_device.c b/src/device/pci_device.c index 689325d2a9..5f50a31460 100644 --- a/src/device/pci_device.c +++ b/src/device/pci_device.c @@ -778,6 +778,13 @@ struct device_operations default_pci_ops_bus = { .reset_bus = pci_bus_reset, }; +/** Default device operations for PCI devices marked 'hidden' */ +static struct device_operations default_hidden_pci_ops_dev = { + .read_resources = noop_read_resources, + .set_resources = noop_set_resources, + .scan_bus = scan_static_bus, +}; + /** * Check for compatibility to route legacy VGA cycles through a bridge. * @@ -1147,6 +1154,46 @@ unsigned int pci_match_simple_dev(struct device *dev, pci_devfn_t sdev) } /** + * PCI devices that are marked as "hidden" do not get probed. However, the same + * initialization logic is still performed as if it were. This is useful when + * devices would like to be described in the devicetree.cb file, and/or present + * static PCI resources to the allocator, but the platform firmware hides the + * device (makes the device invisible to PCI enumeration) before PCI enumeration + * takes place. + * + * The expected semantics of PCI devices marked as 'hidden': + * 1) The device is actually present under the specified BDF + * 2) The device config space can still be accessed somehow, but the Vendor ID + * indicates there is no device there (it reads as 0xffffffff). + * 3) The device may still consume PCI resources. Typically, these would have + * been hardcoded elsewhere. + * + * @param dev Pointer to the device structure. + */ +static void pci_scan_hidden_device(struct device *dev) +{ + if (dev->chip_ops && dev->chip_ops->enable_dev) + dev->chip_ops->enable_dev(dev); + + /* + * If chip_ops->enable_dev did not set dev->ops, then set to a default + * .ops, because PCI enumeration is effectively being skipped, therefore + * no PCI driver will bind to this device. However, children may want to + * be enumerated, so this provides scan_static_bus for the .scan_bus + * callback. + */ + if (dev->ops == NULL) + dev->ops = &default_hidden_pci_ops_dev; + + if (dev->ops->enable) + dev->ops->enable(dev); + + /* Display the device almost as if it were probed normally */ + printk(BIOS_DEBUG, "%s [0000/%04x] hidden%s\n", dev_path(dev), + dev->device, dev->ops ? "" : " No operations"); +} + +/** * Scan a PCI bus. * * Determine the existence of devices and bridges on a PCI bus. If there are @@ -1190,6 +1237,14 @@ void pci_scan_bus(struct bus *bus, unsigned int min_devfn, /* First thing setup the device structure. */ dev = pci_scan_get_dev(bus, devfn); + /* Devices marked 'hidden' do not get probed */ + if (dev && dev->hidden) { + pci_scan_hidden_device(dev); + + /* Skip pci_probe_dev, go to next devfn */ + continue; + } + /* See if a device is present and setup the device structure. */ dev = pci_probe_dev(dev, bus, devfn); @@ -1213,8 +1268,12 @@ void pci_scan_bus(struct bus *bus, unsigned int min_devfn, prev = &bus->children; for (dev = bus->children; dev; dev = dev->sibling) { - /* If we read valid vendor id, it is not leftover device. */ - if (dev->vendor != 0) { + /* + * The device is only considered leftover if it is not hidden + * and it has a Vendor ID of 0 (the default for a device that + * could not be probed). + */ + if (dev->vendor != 0 || dev->hidden) { prev = &dev->sibling; continue; } |