[PATCH] Enabling OF selftest to run without machine's devicetree

[Gaurav Minocha]

If there is no devicetree present, this patch adds the selftest
data as a live devicetree. It also removes the same after the
testcase execution is complete.

Tested with and without machine's devicetree.

Signed-off-by: Gaurav Minocha <gaurav.minocha...@gmail.com>
---
 drivers/of/fdt.c      |    3 +++
 drivers/of/selftest.c |   34 ++++++++++++++++++++++++++++++----
 2 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index b777d8f..18088c0 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -366,6 +366,9 @@ void of_fdt_unflatten_tree(unsigned long *blob,
                        struct device_node **mynodes)
 {
        __unflatten_device_tree(blob, mynodes, &kernel_tree_alloc);
+
+       /* Get pointer to "/chosen" and "/aliases" nodes for use everywhere */
+       of_alias_scan(&kernel_tree_alloc);
 }
 EXPORT_SYMBOL_GPL(of_fdt_unflatten_tree);
 
diff --git a/drivers/of/selftest.c b/drivers/of/selftest.c
index 3a1c5b5..34c9899 100644
--- a/drivers/of/selftest.c
+++ b/drivers/of/selftest.c
@@ -16,6 +16,7 @@
 #include <linux/mutex.h>
 #include <linux/slab.h>
 #include <linux/device.h>
+#include <linux/proc_fs.h>
 
 static struct selftest_results {
        int passed;
@@ -25,6 +26,7 @@ static struct selftest_results {
 #define NO_OF_NODES 2
 static struct device_node *nodes[NO_OF_NODES];
 static int last_node_index;
+static bool selftest_live_tree;
 
 #define selftest(result, fmt, ...) { \
        if (!(result)) { \
@@ -595,7 +597,7 @@ static int attach_node_and_children(struct device_node *np)
 static int __init selftest_data_add(void)
 {
        void *selftest_data;
-       struct device_node *selftest_data_node;
+       struct device_node *selftest_data_node, *np;
        extern uint8_t __dtb_testcases_begin[];
        extern uint8_t __dtb_testcases_end[];
        const int size = __dtb_testcases_end - __dtb_testcases_begin;
@@ -614,10 +616,31 @@ static int __init selftest_data_add(void)
                        "not running tests\n", __func__);
                return -ENOMEM;
        }
-       of_fdt_unflatten_tree(selftest_data, &selftest_data_node);
 
-       /* attach the sub-tree to live tree */
-       return attach_node_and_children(selftest_data_node);
+       if (!of_allnodes) {
+               /* enabling flag for removing nodes */
+               selftest_live_tree = true;
+
+               of_fdt_unflatten_tree(selftest_data, &of_allnodes);
+               if (!of_allnodes) {
+                       pr_warn("%s: No tree to attach; not running tests\n",
+                               __func__);
+                       return -ENODATA;
+               }
+
+               for_each_of_allnodes(np)
+                       of_node_add(np);
+
+               /* Symlink in /proc as required by userspace ABI */
+               proc_symlink("device-tree", NULL, 
"/sys/firmware/devicetree/base");
+
+               return 0;
+       } else {
+               of_fdt_unflatten_tree(selftest_data, &selftest_data_node);
+
+               /* attach the sub-tree to live tree */
+               return attach_node_and_children(selftest_data_node);
+       }
 }
 
 /**
@@ -646,6 +669,9 @@ static void selftest_data_remove(void)
        struct device_node *np;
        struct property *prop;
 
+       if (selftest_live_tree)
+               return detach_node_and_children(of_allnodes);
+
        while (last_node_index >= 0) {
                if (nodes[last_node_index]) {
                        np = 
of_find_node_by_path(nodes[last_node_index]->full_name);
-- 
1.7.9.5

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