PCI: pcie: Ensure hotplug ports have a minimum number of resources

In general a BIOS may goof or we may hotplug in a hotplug controller.
In either case the kernel needs to reserve resources for plugging
in more devices in the future instead of creating a minimal resource
assignment.

We already do this for cardbus bridges I am just adding a variant
for pcie bridges.

v2: Make testing for pcie hotplug bridges based on a flag.

    So far we only set the flag for pcie but a header_quirk
    could easily be added for the non-standard pci hotplug
    bridges.

Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

1 files changed, 18 insertions, 0 deletions

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index ab52840f4753..882383b61d30 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -697,6 +697,23 @@ static void set_pcie_port_type(struct pci_dev *pdev)
         pdev->pcie_type = (reg16 & PCI_EXP_FLAGS_TYPE) >> 4;
 }
 
+static void set_pcie_hotplug_bridge(struct pci_dev *pdev)
+{
+        int pos;
+        u16 reg16;
+        u32 reg32;
+
+        pos = pci_find_capability(pdev, PCI_CAP_ID_EXP);
+        if (!pos)
+                return;
+        pci_read_config_word(pdev, pos + PCI_EXP_FLAGS, &reg16);
+        if (!(reg16 & PCI_EXP_FLAGS_SLOT))
+                return;
+        pci_read_config_dword(pdev, pos + PCI_EXP_SLTCAP, &reg32);
+        if (reg32 & PCI_EXP_SLTCAP_HPC)
+                pdev->is_hotplug_bridge = 1;
+}
+
 #define LEGACY_IO_RESOURCE      (IORESOURCE_IO | IORESOURCE_PCI_FIXED)
 
 /**
@@ -804,6 +821,7 @@ int pci_setup_device(struct pci_dev *dev)
                 pci_read_irq(dev);
                 dev->transparent = ((dev->class & 0xff) == 1);
                 pci_read_bases(dev, 2, PCI_ROM_ADDRESS1);
+                set_pcie_hotplug_bridge(dev);
                 break;
 
         case PCI_HEADER_TYPE_CARDBUS:               /* CardBus bridge header */