[dfs][procfs] Expose the OFW tree through procfs

在 procfs 中导出 OFW 节点和属性，支持二进制属性分段读取，并处理节点冲突及初始化失败清理。

6 files changed, 218 insertions, 3 deletions

diff --git a/components/dfs/Kconfig b/components/dfs/Kconfig
index 4d1418b808..836de72c38 100644
--- a/components/dfs/Kconfig
+++ b/components/dfs/Kconfig
@@ -253,6 +253,15 @@ if RT_USING_DFS_V1
 endif
 
 if RT_USING_DFS_V2
+    config RT_USING_DFS_PROCFS_OFW
+        bool "Expose the OFW tree through procfs"
+        depends on RT_USING_DFS_PROCFS
+        depends on RT_USING_OFW
+        default n
+        help
+            Export the active Open Firmware tree as read-only files under
+            /proc/device-tree.
+
     config RT_USING_PAGECACHE
         bool "Enable page cache"
         default y if RT_USING_SMART
diff --git a/components/dfs/dfs_v2/filesystems/procfs/README.md b/components/dfs/dfs_v2/filesystems/procfs/README.md
index 7ab0127291..bfbf14a56d 100644
--- a/components/dfs/dfs_v2/filesystems/procfs/README.md
+++ b/components/dfs/dfs_v2/filesystems/procfs/README.md
@@ -6,6 +6,7 @@
 struct proc_dentry
 {
     rt_uint32_t mode;
+    rt_size_t size;
     rt_atomic_t ref_count;
 
     struct proc_dentry *parent;
@@ -164,3 +165,12 @@ void proc_remove(struct proc_dentry *dentry);
 - proc_pid
 
  创建一个 pid 目录，`proc_pid /101`
+
+## OFW 设备树导出
+
+在 DFS v2、procfs 和 OFW 均启用时，可选择 `RT_USING_DFS_PROCFS_OFW`，将启动时
+解析的 OFW 树以只读形式导出到 `/proc/device-tree`。节点映射为目录，属性映射为
+只读文件；读取保留设备树属性的原始字节，包括 NUL 结尾字符串、cell 字节序和零长度属性。
+该视图在启动时创建，不跟踪运行时树变更，也不支持属性写入。由于属性和子节点分属不同的
+命名空间，二者可能同名；此时属性优先导出，同名的子节点子树会被跳过并输出告警。导出过程
+中若发生错误，已创建的节点会被整体回滚。
diff --git a/components/dfs/dfs_v2/filesystems/procfs/SConscript b/components/dfs/dfs_v2/filesystems/procfs/SConscript
index 4af49a1b71..cbbc2ce446 100644
--- a/components/dfs/dfs_v2/filesystems/procfs/SConscript
+++ b/components/dfs/dfs_v2/filesystems/procfs/SConscript
@@ -1,11 +1,17 @@
 # RT-Thread building script for component
 
+import os
 from building import *
 
 cwd = GetCurrentDir()
 src = Glob('*.c')
 CPPPATH = [cwd]
 
+if GetDepend(['RT_USING_DFS_PROCFS_OFW']):
+    CPPPATH.append(os.path.normpath(os.path.join(cwd, '../../../../drivers/include')))
+else:
+    SrcRemove(src, ['proc_ofw.c'])
+
 group = DefineGroup('Filesystem', src, depend = ['RT_USING_DFS', 'RT_USING_DFS_PROCFS'], CPPPATH = CPPPATH)
 
 Return('group')
diff --git a/components/dfs/dfs_v2/filesystems/procfs/proc.h b/components/dfs/dfs_v2/filesystems/procfs/proc.h
index e697860e22..7839ae9169 100644
--- a/components/dfs/dfs_v2/filesystems/procfs/proc.h
+++ b/components/dfs/dfs_v2/filesystems/procfs/proc.h
@@ -30,6 +30,7 @@ struct proc_ops
 struct proc_dentry
 {
     rt_uint32_t mode;
+    rt_size_t size;
     rt_atomic_t ref_count;
 
     struct proc_dentry *parent;
diff --git a/components/dfs/dfs_v2/filesystems/procfs/proc_ofw.c b/components/dfs/dfs_v2/filesystems/procfs/proc_ofw.c
new file mode 100644
index 0000000000..19b13baafd
--- /dev/null
+++ b/components/dfs/dfs_v2/filesystems/procfs/proc_ofw.c
@@ -0,0 +1,189 @@
+/*
+ * Copyright (c) 2006-2026, RT-Thread Development Team
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <errno.h>
+#include <rthw.h>
+#include <string.h>
+
+#define DBG_TAG "proc.ofw"
+#define DBG_LVL DBG_INFO
+#include <rtdbg.h>
+
+#include <drivers/ofw.h>
+
+#include "proc.h"
+
+static ssize_t proc_ofw_read(struct dfs_file *file, void *buf, size_t count, off_t *pos)
+{
+    struct proc_dentry *entry;
+    const struct rt_ofw_prop *prop;
+    rt_size_t remaining;
+
+    if (!file || !pos || *pos < 0)
+    {
+        return -EINVAL;
+    }
+
+    if (count == 0)
+    {
+        return 0;
+    }
+
+    if (!buf)
+    {
+        return -EINVAL;
+    }
+
+    entry = (struct proc_dentry *)file->vnode->data;
+    prop = entry ? (const struct rt_ofw_prop *)entry->data : RT_NULL;
+    if (!prop || prop->length < 0)
+    {
+        return -EINVAL;
+    }
+
+    /* compare in off_t before narrowing: *pos may not fit into rt_size_t */
+    if (*pos >= (off_t)prop->length)
+    {
+        return 0;
+    }
+
+    remaining = (rt_size_t)((off_t)prop->length - *pos);
+    if (count > remaining)
+    {
+        count = remaining;
+    }
+
+    if (count && !prop->value)
+    {
+        return -EINVAL;
+    }
+
+    rt_memcpy(buf, (const rt_uint8_t *)prop->value + *pos, count);
+    *pos += count;
+
+    return (ssize_t)count;
+}
+
+static const struct dfs_file_ops proc_ofw_file_ops = {
+    .read = proc_ofw_read,
+    .lseek = generic_dfs_lseek,
+};
+
+static rt_bool_t proc_ofw_has_entry(struct proc_dentry *parent, const char *name)
+{
+    struct proc_dentry *iter, *tmp;
+
+    dfs_vfs_for_each_subnode(iter, tmp, parent, node)
+    {
+        if (iter && !rt_strcmp(iter->name, name))
+        {
+            return RT_TRUE;
+        }
+    }
+
+    return RT_FALSE;
+}
+
+static int proc_ofw_populate_node(const struct rt_ofw_node *node, struct proc_dentry *parent)
+{
+    struct rt_ofw_prop *prop;
+    struct rt_ofw_node *child;
+    struct proc_dentry *dentry;
+    int ret = RT_EOK;
+
+    for (prop = node->props; prop; prop = prop->next)
+    {
+        if (!prop->name || prop->length < 0)
+        {
+            return -RT_ERROR;
+        }
+
+        dentry = proc_create_data(prop->name, 0, parent, &proc_ofw_file_ops, prop);
+        if (!dentry)
+        {
+            return -RT_ERROR;
+        }
+
+        dentry->size = (rt_size_t)prop->length;
+        proc_release(dentry);
+    }
+
+    child = rt_ofw_get_next_child(node, RT_NULL);
+    while (child)
+    {
+        const char *name = rt_ofw_node_full_name(child);
+
+        if (!name || !name[0] || strchr(name, '/'))
+        {
+            rt_ofw_node_put(child);
+            return -RT_ERROR;
+        }
+
+        dentry = proc_mkdir(name, parent);
+        if (!dentry)
+        {
+            if (proc_ofw_has_entry(parent, name))
+            {
+                /* a property and a child node may share the same name, the
+                 * property has been exported already, so skip this subtree */
+                LOG_W("%s: a property with the same name exists, skip the node", name);
+                child = rt_ofw_get_next_child(node, child);
+                continue;
+            }
+
+            rt_ofw_node_put(child);
+            return -RT_ENOMEM;
+        }
+
+        ret = proc_ofw_populate_node(child, dentry);
+        proc_release(dentry);
+        if (ret != RT_EOK)
+        {
+            rt_ofw_node_put(child);
+            return ret;
+        }
+
+        child = rt_ofw_get_next_child(node, child);
+    }
+
+    return ret;
+}
+
+static int proc_ofw_init(void)
+{
+    struct rt_ofw_node *root;
+    struct proc_dentry *dentry;
+    int ret;
+
+    root = rt_ofw_find_node_by_path("/");
+    if (!root)
+    {
+        LOG_W("OFW tree is unavailable");
+        return RT_EOK;
+    }
+
+    dentry = proc_mkdir("device-tree", RT_NULL);
+    if (!dentry)
+    {
+        rt_ofw_node_put(root);
+        LOG_E("failed to create /proc/device-tree");
+        return -RT_ERROR;
+    }
+
+    ret = proc_ofw_populate_node(root, dentry);
+    if (ret != RT_EOK)
+    {
+        /* remove the partially created subtree before dropping our reference */
+        LOG_E("failed to export the OFW tree through procfs");
+        proc_remove(dentry);
+    }
+
+    proc_release(dentry);
+    rt_ofw_node_put(root);
+
+    return ret;
+}
+INIT_ENV_EXPORT(proc_ofw_init);
diff --git a/components/dfs/dfs_v2/filesystems/procfs/procfs.c b/components/dfs/dfs_v2/filesystems/procfs/procfs.c
index 8cba8ed48c..329dd53f0a 100644
--- a/components/dfs/dfs_v2/filesystems/procfs/procfs.c
+++ b/components/dfs/dfs_v2/filesystems/procfs/procfs.c
@@ -145,11 +145,11 @@ static int dfs_procfs_getdents(struct dfs_file *file, struct dirent *dirp, uint3
             {
                 d = dirp + index - file->fpos;
 
-                if (S_ISDIR(entry->mode))
+                if (S_ISDIR(iter->mode))
                 {
                     d->d_type = DT_DIR;
                 }
-                else if (S_ISLNK(entry->mode))
+                else if (S_ISLNK(iter->mode))
                 {
                     d->d_type = DT_SYMLINK;
                 }
@@ -340,7 +340,7 @@ static struct dfs_vnode *dfs_procfs_lookup(struct dfs_dentry *dentry)
         if (vnode)
         {
             vnode->nlink = 1;
-            vnode->size = 0;
+            vnode->size = entry->size;
             if (S_ISDIR(entry->mode))
             {
                 vnode->mode = entry->mode;