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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 <rrichter@amd.com>
[djbw: rebase on brige mocking]
Reviewed-by: Robert Richter <rrichter@amd.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/166993043978.1882361.16238060349889579369.stgit@dwillia2-xfh.jf.intel.com
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This commit is contained in:
Robert Richter 2022-12-01 13:33:59 -08:00 committed by Dan Williams
parent 8b3b1c0dc5
commit 1dedb6f3cf
1 changed files with 20 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

38
drivers/cxl/acpi.c
View File

@ -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);