cxl/core: Fix cxl_dport debugfs EINJ entries

Protocol error injection is only valid for CXL 2.0+ root ports and CXL
1.1 memory-mapped downstream ports as per the ACPI v6.5 spec (Table
8-31). The core code currently creates an 'einj_inject' file in CXL debugfs
for all CXL 1.1 downstream ports and all PCI CXL 2.0+ downstream ports.
This results in debugfs EINJ files that won't work due to platform/spec
restrictions.

Fix by limiting 'einj_inject' file creation to only CXL 1.1 dports and
CXL 2.0+ root ports. Update the comment above the check to more accurately
represent the requirements expected by the EINJ module and ACPI spec.

Fixes: 8039804 ("cxl/core: Add CXL EINJ debugfs files")
Signed-off-by: Ben Cheatham <Benjamin.Cheatham@amd.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Link: https://patch.msgid.link/6e9fb657-8264-4028-92e2-5428e2695bf1@amd.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>

Author: benhartcheatham

drivers/cxl/core/port.c

@@ -822,16 +822,18 @@ DEFINE_DEBUGFS_ATTRIBUTE(cxl_einj_inject_fops, NULL, cxl_einj_inject,
 
 static void cxl_debugfs_create_dport_dir(struct cxl_dport *dport)
 {
+	struct cxl_port *parent = parent_port_of(dport->port);
 	struct dentry *dir;
 
 	if (!einj_cxl_is_initialized())
 		return;
 
 	/*
-	 * dport_dev needs to be a PCIe port for CXL 2.0+ ports because
-	 * EINJ expects a dport SBDF to be specified for 2.0 error injection.
+	 * Protocol error injection is only available for CXL 2.0+ root ports
+	 * and CXL 1.1 downstream ports
 	 */
-	if (!dport->rch && !dev_is_pci(dport->dport_dev))
+	if (!dport->rch &&
+	    !(dev_is_pci(dport->dport_dev) && parent && is_cxl_root(parent)))
 		return;
 
 	dir = cxl_debugfs_create_dir(dev_name(dport->dport_dev));