[Qemu-devel] [PATCH 1/2] device_tree: introduce qemu_fdt_node_path_prop

[Bogdan Purcareata <bogdan.purcareata@nxp.com>]

This new helper routine returns a NULL terminated array of
node paths matching a property and, optionally, a name.

Signed-off-by: Bogdan Purcareata <bogdan.purcareata@nxp.com>
---
 device_tree.c                | 59 ++++++++++++++++++++++++++++++++++++++++++++
 include/sysemu/device_tree.h | 20 +++++++++++++++
 2 files changed, 79 insertions(+)

diff --git a/device_tree.c b/device_tree.c
index ccba1fd..85c81cc 100644
--- a/device_tree.c
+++ b/device_tree.c
@@ -281,6 +281,65 @@ char **qemu_fdt_node_path(void *fdt, const char *name, char *compat,
     return path_array;
 }
 
+char **qemu_fdt_node_path_prop(void *fdt, const char *name,
+       const char *pname, const void *pval, int plen, Error **errp)
+{
+    int offset, len, ret;
+    const char *iter_name;
+    unsigned int path_len = 16, n = 0;
+    GSList *path_list = NULL, *iter;
+    char **path_array;
+
+    for (offset = fdt_node_offset_by_prop_value(fdt, 0, pname, pval, plen);
+    offset >= 0;
+    offset = fdt_node_offset_by_prop_value(fdt, offset, pname, pval, plen)) {
+
+        iter_name = fdt_get_name(fdt, offset, &len);
+
+        if (!iter_name) {
+            continue;
+        }
+
+        /* if the node doesn't match the name, move on */
+        if (name && strncmp(iter_name, name, strlen(name))) {
+            continue;
+        }
+
+        char *path;
+
+        path = g_malloc(path_len);
+        while ((ret = fdt_get_path(fdt, offset, path, path_len)) ==
+                    -FDT_ERR_NOSPACE) {
+            path_len += 16;
+            path = g_realloc(path, path_len);
+        }
+
+        path_list = g_slist_prepend(path_list, path);
+        n++;
+    }
+
+    if (offset < 0 && offset != -FDT_ERR_NOTFOUND) {
+        error_setg(errp, "%s: abort parsing dt for %s/%s: %s",
+                   __func__, name, pname, fdt_strerror(offset));
+        for (iter = path_list; iter; iter = iter->next) {
+            g_free(iter->data);
+        }
+        g_slist_free(path_list);
+        return NULL;
+    }
+
+    path_array = g_new(char *, n + 1);
+    path_array[n--] = NULL;
+
+    for (iter = path_list; iter; iter = iter->next) {
+        path_array[n--] = iter->data;
+    }
+
+    g_slist_free(path_list);
+
+    return path_array;
+}
+
 int qemu_fdt_setprop(void *fdt, const char *node_path,
                      const char *property, const void *val, int size)
 {
diff --git a/include/sysemu/device_tree.h b/include/sysemu/device_tree.h
index 705650a..03c8193 100644
--- a/include/sysemu/device_tree.h
+++ b/include/sysemu/device_tree.h
@@ -43,6 +43,26 @@ void *load_device_tree_from_sysfs(void);
 char **qemu_fdt_node_path(void *fdt, const char *name, char *compat,
                           Error **errp);
 
+/**
+ * qemu_fdt_node_path_property: return the paths of nodes matching a given
+ * property and, optionally, a name string
+ * @fdt: pointer to the dt blob
+ * @name: node name (can be NULL) - if NULL, will return all nodes mathing prop
+ * @propname: property name
+ * @propvalue: property value (can be NULL)
+ * @proplen: property length (can be 0)
+ * @errp: handle to an error object
+ *
+ * returns a newly allocated NULL-terminated array of node paths.
+ * Use g_strfreev() to free it. If one or more nodes were found, the
+ * array contains the path of each node and the last element equals to
+ * NULL. If there is no error but no matching node was found, the
+ * returned array contains a single element equal to NULL. If an error
+ * was encountered when parsing the blob, the function returns NULL
+ */
+char **qemu_fdt_node_path_prop(void *fdt, const char *name,
+    const char *propname, const void *propvalue, int proplen, Error **errp);
+
 int qemu_fdt_setprop(void *fdt, const char *node_path,
                      const char *property, const void *val, int size);
 int qemu_fdt_setprop_cell(void *fdt, const char *node_path,
-- 
1.9.1