[ndctl PATCH v2 07/18] cxl/list: Add parent_dport attribute to port listings

[Dan Williams]

---
 cxl/json.c         |    8 ++++++++
 cxl/lib/libcxl.c   |   38 ++++++++++++++++++++++++++++++++++++++
 cxl/lib/libcxl.sym |    1 +
 cxl/lib/private.h  |    2 ++
 cxl/libcxl.h       |    1 +
 5 files changed, 50 insertions(+)

diff --git a/cxl/json.c b/cxl/json.c
index 5cff532acb13..2f3639ede2f8 100644
--- a/cxl/json.c
+++ b/cxl/json.c
@@ -783,6 +783,14 @@ static struct json_object *__util_cxl_port_to_json(struct 
cxl_port *port,
        if (jobj)
                json_object_object_add(jport, "host", jobj);
 
+       if (cxl_port_get_parent_dport(port)) {
+               struct cxl_dport *dport = cxl_port_get_parent_dport(port);
+
+               jobj = json_object_new_string(cxl_dport_get_devname(dport));
+               if (jobj)
+                       json_object_object_add(jport, "parent_dport", jobj);
+       }
+
        jobj = json_object_new_int(cxl_port_get_depth(port));
        if (jobj)
                json_object_object_add(jport, "depth", jobj);
diff --git a/cxl/lib/libcxl.c b/cxl/lib/libcxl.c
index a69e31bc8a6e..9475d0e51f8c 100644
--- a/cxl/lib/libcxl.c
+++ b/cxl/lib/libcxl.c
@@ -162,6 +162,7 @@ static void __free_port(struct cxl_port *port, struct 
list_head *head)
        free(port->dev_buf);
        free(port->dev_path);
        free(port->uport);
+       free(port->parent_dport_path);
 }
 
 static void free_port(struct cxl_port *port, struct list_head *head)
@@ -1488,6 +1489,20 @@ static int cxl_port_init(struct cxl_port *port, struct 
cxl_port *parent_port,
        if (!port->uport)
                goto err;
 
+       /*
+        * CXL root devices have no parents and level 1 ports are both
+        * CXL root targets and hosts of the next level, so:
+        *     parent_dport == uport
+        * ...at depth == 1
+        */
+       if (port->depth > 1) {
+               rc = snprintf(port->dev_buf, port->buf_len, "%s/parent_dport",
+                             cxlport_base);
+               if (rc >= port->buf_len)
+                       goto err;
+               port->parent_dport_path = realpath(port->dev_buf, NULL);
+       }
+
        sprintf(path, "%s/modalias", cxlport_base);
        if (sysfs_read_attr(ctx, path, buf) == 0)
                port->module = util_modalias_to_module(ctx, buf);
@@ -2465,6 +2480,29 @@ CXL_EXPORT const char *cxl_port_get_host(struct cxl_port 
*port)
        return devpath_to_devname(port->uport);
 }
 
+CXL_EXPORT struct cxl_dport *cxl_port_get_parent_dport(struct cxl_port *port)
+{
+       struct cxl_port *parent;
+       struct cxl_dport *dport;
+       const char *name;
+
+       if (port->parent_dport)
+               return port->parent_dport;
+
+       if (!port->parent_dport_path)
+               return NULL;
+
+       parent = cxl_port_get_parent(port);
+       name = devpath_to_devname(port->parent_dport_path);
+       cxl_dport_foreach(parent, dport)
+               if (strcmp(cxl_dport_get_devname(dport), name) == 0) {
+                       port->parent_dport = dport;
+                       return dport;
+               }
+
+       return NULL;
+}
+
 CXL_EXPORT bool cxl_port_hosts_memdev(struct cxl_port *port,
                                      struct cxl_memdev *memdev)
 {
diff --git a/cxl/lib/libcxl.sym b/cxl/lib/libcxl.sym
index 490ed1fda5d3..cc5c1d543484 100644
--- a/cxl/lib/libcxl.sym
+++ b/cxl/lib/libcxl.sym
@@ -222,4 +222,5 @@ LIBCXL_4 {
 global:
        cxl_target_get_firmware_node;
        cxl_dport_get_firmware_node;
+       cxl_port_get_parent_dport;
 } LIBCXL_3;
diff --git a/cxl/lib/private.h b/cxl/lib/private.h
index e378339ec353..da2fce33cb07 100644
--- a/cxl/lib/private.h
+++ b/cxl/lib/private.h
@@ -62,6 +62,8 @@ struct cxl_port {
        size_t buf_len;
        char *dev_path;
        char *uport;
+       char *parent_dport_path;
+       struct cxl_dport *parent_dport;
        int ports_init;
        int endpoints_init;
        int decoders_init;
diff --git a/cxl/libcxl.h b/cxl/libcxl.h
index 1e0076908901..8d75330886f8 100644
--- a/cxl/libcxl.h
+++ b/cxl/libcxl.h
@@ -96,6 +96,7 @@ bool cxl_port_is_endpoint(struct cxl_port *port);
 struct cxl_endpoint *cxl_port_to_endpoint(struct cxl_port *port);
 struct cxl_bus *cxl_port_get_bus(struct cxl_port *port);
 const char *cxl_port_get_host(struct cxl_port *port);
+struct cxl_dport *cxl_port_get_parent_dport(struct cxl_port *port);
 bool cxl_port_hosts_memdev(struct cxl_port *port, struct cxl_memdev *memdev);
 int cxl_port_get_nr_dports(struct cxl_port *port);
 int cxl_port_disable_invalidate(struct cxl_port *port);