From 1dedb6f3cf7feeb84b10c24046d8e4436173cc4d Mon Sep 17 00:00:00 2001 From: Robert Richter Date: Thu, 1 Dec 2022 13:33:59 -0800 Subject: [PATCH] cxl/ACPI: Register CXL host ports by bridge device 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. Signed-off-by: Robert Richter [djbw: rebase on brige mocking] Reviewed-by: Robert Richter Reviewed-by: Dave Jiang Link: https://lore.kernel.org/r/166993043978.1882361.16238060349889579369.stgit@dwillia2-xfh.jf.intel.com Reviewed-by: Jonathan Cameron Signed-off-by: Dan Williams --- drivers/cxl/acpi.c | 38 ++++++++++++++++++++------------------ 1 file changed, 20 insertions(+), 18 deletions(-) diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c index 2992bac4c0e4..694868a85c93 100644 --- a/drivers/cxl/acpi.c +++ b/drivers/cxl/acpi.c @@ -197,35 +197,34 @@ 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_device *hb = to_cxl_host_bridge(host, match); struct acpi_pci_root *pci_root; struct cxl_dport *dport; struct cxl_port *port; + struct device *bridge; int rc; - if (!bridge) + if (!hb) return 0; - dport = cxl_find_dport_by_dev(root_port, match); + pci_root = acpi_pci_find_root(hb->handle); + bridge = pci_root->bus->bridge; + 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; } @@ -256,20 +255,21 @@ static int cxl_get_chbcr(union acpi_subtable_headers *header, void *arg, static int add_host_bridge_dport(struct device *match, void *arg) { - acpi_status status; + acpi_status rc; + struct device *bridge; unsigned long long uid; struct cxl_dport *dport; struct cxl_chbs_context ctx; + struct acpi_pci_root *pci_root; 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_device *hb = to_cxl_host_bridge(host, match); - if (!bridge) + if (!hb) return 0; - status = acpi_evaluate_integer(bridge->handle, METHOD_NAME__UID, NULL, - &uid); - if (status != AE_OK) { + rc = acpi_evaluate_integer(hb->handle, METHOD_NAME__UID, NULL, &uid); + if (rc != AE_OK) { dev_err(match, "unable to retrieve _UID\n"); return -ENODEV; } @@ -289,7 +289,9 @@ 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); + pci_root = acpi_pci_find_root(hb->handle); + bridge = pci_root->bus->bridge; + dport = devm_cxl_add_dport(root_port, bridge, uid, ctx.chbcr); if (IS_ERR(dport)) return PTR_ERR(dport);