Messages in this thread Patch in this message | | | From | Robert Richter <> | Subject | [PATCH v3 1/9] cxl/acpi: Register CXL host ports by bridge device | Date | Wed, 9 Nov 2022 11:40:51 +0100 |
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A port of a CXL host bridge links to the bridge's acpi device (&adev->dev) with its corresponding uport/dport device (uport_dev and dport_dev respectively). The device is not a direct parent device in the PCI topology as pdev->dev.parent points to a PCI bridge's (struct pci_host_bridge) device. The following CXL memory device hierarchy would be valid for an endpoint once an RCD EP would be enabled (note this will be done in a later patch):
VH mode:
cxlmd->dev.parent->parent ^^^\^^^^^^\ ^^^^^^\ \ \ pci_dev (Type 1, Downstream Port) \ pci_dev (Type 0, PCI Express Endpoint) cxl mem device
RCD mode:
cxlmd->dev.parent->parent ^^^\^^^^^^\ ^^^^^^\ \ \ pci_host_bridge \ pci_dev (Type 0, RCiEP) cxl mem device
In VH mode a downstream port is created by port enumeration and thus always exists.
Now, in RCD mode the host bridge also already exists but it references to an ACPI device. A port lookup by the PCI device's parent device will fail as a direct link to the registered port is missing. The ACPI device of the bridge must be determined first.
To prevent this, change port registration of a CXL host to use the bridge device instead. Do this also for the VH case as port topology will better reflect the PCI topology then.
If a mock device is registered by a test driver, the bridge pointer can be NULL. Keep using the matching ACPI device (&adev->dev) as a fallback in this case.
Signed-off-by: Robert Richter <rrichter@amd.com> --- drivers/cxl/acpi.c | 48 ++++++++++++++++++++++++++++++---------------- 1 file changed, 31 insertions(+), 17 deletions(-)
diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c index fb9f72813067..06150c953f58 100644 --- a/drivers/cxl/acpi.c +++ b/drivers/cxl/acpi.c @@ -185,6 +185,17 @@ __mock struct acpi_device *to_cxl_host_bridge(struct device *host, return NULL; } +static inline struct acpi_pci_root *to_cxl_pci_root(struct device *host, + struct device *match) +{ + struct acpi_device *adev = to_cxl_host_bridge(host, match); + + if (!adev) + return NULL; + + return acpi_pci_find_root(adev->handle); +} + /* * A host bridge is a dport to a CFMWS decode and it is a uport to the * dport (PCIe Root Ports) in the host bridge. @@ -193,35 +204,35 @@ static int add_host_bridge_uport(struct device *match, void *arg) { struct cxl_port *root_port = arg; struct device *host = root_port->dev.parent; - struct acpi_device *bridge = to_cxl_host_bridge(host, match); - struct acpi_pci_root *pci_root; + struct acpi_pci_root *pci_root = to_cxl_pci_root(host, match); struct cxl_dport *dport; struct cxl_port *port; + struct device *bridge; int rc; - if (!bridge) + if (!pci_root) return 0; - dport = cxl_find_dport_by_dev(root_port, match); + /* + * If it is a mock dev, the bridge can be NULL, use matching + * device (&adev->dev) as a fallback then then. + */ + bridge = pci_root->bus->bridge ?: match; + dport = cxl_find_dport_by_dev(root_port, bridge); if (!dport) { dev_dbg(host, "host bridge expected and not found\n"); return 0; } - /* - * Note that this lookup already succeeded in - * to_cxl_host_bridge(), so no need to check for failure here - */ - pci_root = acpi_pci_find_root(bridge->handle); - rc = devm_cxl_register_pci_bus(host, match, pci_root->bus); + rc = devm_cxl_register_pci_bus(host, bridge, pci_root->bus); if (rc) return rc; - port = devm_cxl_add_port(host, match, dport->component_reg_phys, dport); + port = devm_cxl_add_port(host, bridge, dport->component_reg_phys, dport); if (IS_ERR(port)) return PTR_ERR(port); - dev_info(pci_root->bus->bridge, "host supports CXL\n"); + dev_info(bridge, "host supports CXL\n"); return 0; } @@ -258,13 +269,16 @@ static int add_host_bridge_dport(struct device *match, void *arg) struct cxl_chbs_context ctx; struct cxl_port *root_port = arg; struct device *host = root_port->dev.parent; - struct acpi_device *bridge = to_cxl_host_bridge(host, match); + struct acpi_pci_root *pci_root = to_cxl_pci_root(host, match); + struct device *bridge; + acpi_handle handle; - if (!bridge) + if (!pci_root) return 0; - status = acpi_evaluate_integer(bridge->handle, METHOD_NAME__UID, NULL, - &uid); + bridge = pci_root->bus->bridge ?: match; + handle = pci_root->device->handle; + status = acpi_evaluate_integer(handle, METHOD_NAME__UID, NULL, &uid); if (status != AE_OK) { dev_err(match, "unable to retrieve _UID\n"); return -ENODEV; @@ -285,7 +299,7 @@ static int add_host_bridge_dport(struct device *match, void *arg) dev_dbg(match, "CHBCR found: 0x%08llx\n", (u64)ctx.chbcr); - dport = devm_cxl_add_dport(root_port, match, uid, ctx.chbcr); + dport = devm_cxl_add_dport(root_port, bridge, uid, ctx.chbcr); if (IS_ERR(dport)) return PTR_ERR(dport); -- 2.30.2
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