cxl/mem: Enumerate port targets before adding endpoints

The port scanning algorithm in devm_cxl_enumerate_ports() walks up the
topology and adds cxl_port objects starting from the root down to the
endpoint. When those ports are initially created they know all their
dports, but they do not know the downstream cxl_port instance that
represents the next descendant in the topology. Rework create_endpoint()
into devm_cxl_add_endpoint() that enumerates the downstream cxl_port
topology into each port's 'struct cxl_ep' record for each endpoint it
that the port is an ancestor.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/20220624041950.559155-7-dan.j.williams@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
index 719563d..60c637a 100644 (file)
--- a/drivers/cxl/core/port.c
+++ b/drivers/cxl/core/port.c
@@ -1087,6 +1087,47 @@ static struct cxl_ep *cxl_ep_load(struct cxl_port *port,
        return xa_load(&port->endpoints, (unsigned long)&cxlmd->dev);
 }
 
+int devm_cxl_add_endpoint(struct cxl_memdev *cxlmd,
+                         struct cxl_dport *parent_dport)
+{
+       struct cxl_port *parent_port = parent_dport->port;
+       struct cxl_dev_state *cxlds = cxlmd->cxlds;
+       struct cxl_port *endpoint, *iter, *down;
+       int rc;
+
+       /*
+        * Now that the path to the root is established record all the
+        * intervening ports in the chain.
+        */
+       for (iter = parent_port, down = NULL; !is_cxl_root(iter);
+            down = iter, iter = to_cxl_port(iter->dev.parent)) {
+               struct cxl_ep *ep;
+
+               ep = cxl_ep_load(iter, cxlmd);
+               ep->next = down;
+       }
+
+       endpoint = devm_cxl_add_port(&parent_port->dev, &cxlmd->dev,
+                                    cxlds->component_reg_phys, parent_dport);
+       if (IS_ERR(endpoint))
+               return PTR_ERR(endpoint);
+
+       dev_dbg(&cxlmd->dev, "add: %s\n", dev_name(&endpoint->dev));
+
+       rc = cxl_endpoint_autoremove(cxlmd, endpoint);
+       if (rc)
+               return rc;
+
+       if (!endpoint->dev.driver) {
+               dev_err(&cxlmd->dev, "%s failed probe\n",
+                       dev_name(&endpoint->dev));
+               return -ENXIO;
+       }
+
+       return 0;
+}
+EXPORT_SYMBOL_NS_GPL(devm_cxl_add_endpoint, CXL);
+
 static void cxl_detach_ep(void *data)
 {
        struct cxl_memdev *cxlmd = data;

diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index ac950fb..c3c6256 100644 (file)
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -385,10 +385,13 @@ struct cxl_dport {
  * struct cxl_ep - track an endpoint's interest in a port
  * @ep: device that hosts a generic CXL endpoint (expander or accelerator)
  * @dport: which dport routes to this endpoint on @port
+ * @next: cxl switch port across the link attached to @dport NULL if
+ *       attached to an endpoint
  */
 struct cxl_ep {
        struct device *ep;
        struct cxl_dport *dport;
+       struct cxl_port *next;
 };
 
 /*
@@ -411,6 +414,8 @@ struct pci_bus *cxl_port_to_pci_bus(struct cxl_port *port);
 struct cxl_port *devm_cxl_add_port(struct device *host, struct device *uport,
                                   resource_size_t component_reg_phys,
                                   struct cxl_dport *parent_dport);
+int devm_cxl_add_endpoint(struct cxl_memdev *cxlmd,
+                         struct cxl_dport *parent_dport);
 struct cxl_port *find_cxl_root(struct device *dev);
 int devm_cxl_enumerate_ports(struct cxl_memdev *cxlmd);
 int cxl_bus_rescan(void);

diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c
index 2786d34..64ccf05 100644 (file)
--- a/drivers/cxl/mem.c
+++ b/drivers/cxl/mem.c
@@ -25,34 +25,6 @@
  * in higher level operations.
  */
 
-static int create_endpoint(struct cxl_memdev *cxlmd,
-                          struct cxl_dport *parent_dport)
-{
-       struct cxl_port *parent_port = parent_dport->port;
-       struct cxl_dev_state *cxlds = cxlmd->cxlds;
-       struct cxl_port *endpoint;
-       int rc;
-
-       endpoint = devm_cxl_add_port(&parent_port->dev, &cxlmd->dev,
-                                    cxlds->component_reg_phys, parent_dport);
-       if (IS_ERR(endpoint))
-               return PTR_ERR(endpoint);
-
-       dev_dbg(&cxlmd->dev, "add: %s\n", dev_name(&endpoint->dev));
-
-       rc = cxl_endpoint_autoremove(cxlmd, endpoint);
-       if (rc)
-               return rc;
-
-       if (!endpoint->dev.driver) {
-               dev_err(&cxlmd->dev, "%s failed probe\n",
-                       dev_name(&endpoint->dev));
-               return -ENXIO;
-       }
-
-       return 0;
-}
-
 static void enable_suspend(void *data)
 {
        cxl_mem_active_dec();
@@ -116,7 +88,7 @@ static int cxl_mem_probe(struct device *dev)
                goto unlock;
        }
 
-       rc = create_endpoint(cxlmd, dport);
+       rc = devm_cxl_add_endpoint(cxlmd, dport);
 unlock:
        device_unlock(&parent_port->dev);
        put_device(&parent_port->dev);