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[xen staging] xen: workaround missing device_type property in pci/pcie nodes

commit 5a4087004d1adbbb223925f3306db0e5824a2bdc
Author:     Stefano Stabellini <sstabellini@xxxxxxxxxx>
AuthorDate: Tue Feb 9 11:53:34 2021 -0800
Commit:     Stefano Stabellini <sstabellini@xxxxxxxxxx>
CommitDate: Thu Feb 11 17:52:36 2021 -0800

    xen: workaround missing device_type property in pci/pcie nodes
    PCI buses differ from default buses in a few important ways, so it is
    important to detect them properly. Normally, PCI buses are expected to
    have the following property:
        device_type = "pci"
    In reality, it is not always the case. To handle PCI bus nodes that
    don't have the device_type property, also consider the node name: if the
    node name is "pcie" or "pci" then consider the bus as a PCI bus.
    This commit is based on the Linux kernel commit
    d1ac0002dd29 "of: address: Work around missing device_type property in
    pcie nodes".
    This fixes Xen boot on RPi4. Some RPi4 kernels have the following node
    on their device trees:
    &pcie0 {
            pci@1,0 {
                    #address-cells = <3>;
                    #size-cells = <2>;
                    reg = <0 0 0 0 0>;
                    usb@1,0 {
                            reg = <0x10000 0 0 0 0>;
                            resets = <&reset RASPBERRYPI_FIRMWARE_RESET_ID_USB>;
    The pci@1,0 node is a PCI bus. If we parse the node and its children as
    a default bus, the reg property under usb@1,0 would have to be
    interpreted as an address range mappable by the CPU, which is not the
    case and would break.
    Link: https://lore.kernel.org/xen-devel/YBmQQ3Tzu++AadKx@xxxxxxxxxxxxxxxx/
    [fix style on commit]
    Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxx>
    Tested-by: Elliott Mitchell <ehem+xen@xxxxxxx>
    Tested-by: Jukka Kaartinen <jukka.kaartinen@xxxxxxxxxx>
    Reviewed-by: Bertrand Marquis <bertrand.marquis@xxxxxxx>
    Acked-by: Julien Grall <jgrall@xxxxxxxxxx>
 xen/common/device_tree.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/xen/common/device_tree.c b/xen/common/device_tree.c
index 18825e333e..03d25a81ce 100644
--- a/xen/common/device_tree.c
+++ b/xen/common/device_tree.c
@@ -563,14 +563,28 @@ static unsigned int dt_bus_default_get_flags(const __be32 
  * PCI bus specific translator
+static bool dt_node_is_pci(const struct dt_device_node *np)
+    bool is_pci = !strcmp(np->name, "pcie") || !strcmp(np->name, "pci");
+    if ( is_pci )
+        printk(XENLOG_WARNING "%s: Missing device_type\n", np->full_name);
+    return is_pci;
 static bool_t dt_bus_pci_match(const struct dt_device_node *np)
      * "pciex" is PCI Express "vci" is for the /chaos bridge on 1st-gen PCI
      * powermacs "ht" is hypertransport
+     *
+     * If none of the device_type match, and that the node name is
+     * "pcie" or "pci", accept the device as PCI (with a warning).
     return !strcmp(np->type, "pci") || !strcmp(np->type, "pciex") ||
-        !strcmp(np->type, "vci") || !strcmp(np->type, "ht");
+        !strcmp(np->type, "vci") || !strcmp(np->type, "ht") ||
+        dt_node_is_pci(np);
 static void dt_bus_pci_count_cells(const struct dt_device_node *np,
generated by git-patchbot for /home/xen/git/xen.git#staging



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