This function returns the host device tree blob from sysfs
(/sys/firmware/devicetree/base). It uses a recursive function
inspired from dtc read_fstree.
Signed-off-by: Eric Auger <eric.au...@linaro.org>
---
RFC -> v1:
- remove runtime dependency on dtc binary and introduce read_fstree
---
device_tree.c | 102 +++++++++++++++++++++++++++++++++++++++++++
include/sysemu/device_tree.h | 1 +
2 files changed, 103 insertions(+)
diff --git a/device_tree.c b/device_tree.c
index a9f5f8e..e556a99 100644
--- a/device_tree.c
+++ b/device_tree.c
@@ -17,6 +17,7 @@
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
+#include <dirent.h>
#include "qemu-common.h"
#include "qemu/error-report.h"
@@ -117,6 +118,107 @@ fail:
return NULL;
}
+/**
+ * read_fstree: this function is inspired from dtc read_fstree
+ * @fdt: preallocated fdt blob buffer, to be populated
+ * @dirname: directory to scan under /sys/firmware/devicetree/base
+ * the search is recursive and the tree is search down to the
+ * leafs (property files).
+ *
+ * the function self-asserts in case of error
+ */
+static void read_fstree(void *fdt, const char *dirname)
+{
+ DIR *d;
+ struct dirent *de;
+ struct stat st;
+ const char *root_dir = "/sys/firmware/devicetree/base";
+ char *parent_node;
+
+ if (strstr(dirname, root_dir) != dirname) {
+ error_report("%s: %s must be searched within %s",
+ __func__, dirname, root_dir);
+ exit(1);
+ }
+ parent_node = (char *)&dirname[29];
+
+ d = opendir(dirname);
+ if (!d) {
+ error_report("%s cannot open %s", __func__, dirname);
+ exit(1);
+ }
+
+ while ((de = readdir(d)) != NULL) {
+ char *tmpnam;
+
+ if (!g_strcmp0(de->d_name, ".")
+ || !g_strcmp0(de->d_name, "..")) {
+ continue;
+ }
+
+ tmpnam = g_strjoin("/", dirname, de->d_name, NULL);
+
+ if (lstat(tmpnam, &st) < 0) {
+ error_report("%s cannot lstat %s", __func__, tmpnam);
+ exit(1);
+ }
+
+ if (S_ISREG(st.st_mode)) {
+ int ret, size = st.st_size;
+ void *val = g_malloc0(size);
+ FILE *pfile;
+
+ pfile = fopen(tmpnam, "r");
+ if (!pfile) {
+ error_report("%s cannot open %s", __func__, tmpnam);
+ exit(1);
+ }
+ ret = fread(val, 1, size, pfile);
+ if (ferror(pfile) || ret < size) {
+ error_report("%s fail reading %s", __func__, tmpnam);
+ exit(1);
+ }
+ fclose(pfile);
+
+ if (strlen(parent_node) > 0) {
+ qemu_fdt_setprop(fdt, parent_node,
+ de->d_name, val, size);
+ } else {
+ qemu_fdt_setprop(fdt, "/", de->d_name, val, size);
+ }
+ g_free(val);
+ } else if (S_ISDIR(st.st_mode)) {
+ char *node_name;
+
+ node_name = g_strdup_printf("%s/%s",
+ parent_node, de->d_name);
+ qemu_fdt_add_subnode(fdt, node_name);
+ g_free(node_name);
+ read_fstree(fdt, tmpnam);
+ }
+
+ g_free(tmpnam);
+ }
+
+ closedir(d);
+}
+
+/* load_device_tree_from_sysfs: extract the dt blob from host sysfs */
+void *load_device_tree_from_sysfs(void)
+{
+ void *host_fdt;
+ int host_fdt_size;
+
+ host_fdt = create_device_tree(&host_fdt_size);
+ read_fstree(host_fdt, "/sys/firmware/devicetree/base");
+ if (fdt_check_header(host_fdt)) {
+ error_report("%s host device tree extracted into memory is invalid",
+ __func__);
+ g_free(host_fdt);
+ }
+ return host_fdt;
+}
+
static int findnode_nofail(void *fdt, const char *node_path)
{
int offset;
diff --git a/include/sysemu/device_tree.h b/include/sysemu/device_tree.h
index 359e143..307e53d 100644
--- a/include/sysemu/device_tree.h
+++ b/include/sysemu/device_tree.h
@@ -16,6 +16,7 @@
void *create_device_tree(int *sizep);
void *load_device_tree(const char *filename_path, int *sizep);
+void *load_device_tree_from_sysfs(void);
int qemu_fdt_setprop(void *fdt, const char *node_path,
const char *property, const void *val, int size);
--
1.9.1
