[OSS-Tools] [PATCH 4/5] libdt: add CONFIG_TEST_LOOPBACK

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

We have quite a bit of tricky udev and device tree parsing code that is
only tested manually. Best case we would have tests for this in QEMU,
but until we do, let's test it with loop devices:

The downside is that we can only test block devices and that we need
a tiny bit of code that's not used normally, but on the upside, we
have tests. :-)

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 configure.ac |  2 ++
 meson.build  |  1 +
 src/dt/dt.h  |  1 -
 src/libdt.c  | 50 +++++++++++++++++++++++++++++++++++++++++++++++---
 4 files changed, 50 insertions(+), 4 deletions(-)

diff --git a/configure.ac b/configure.ac
index 117a1e169ba9..5b5c74c2b582 100644
--- a/configure.ac
+++ b/configure.ac
@@ -40,6 +40,8 @@ AC_DEFINE(CONFIG_MTD, [1], [Statically define to be enabled to harmonize barebox
 
 AC_DEFINE(CONFIG_STATE, [1], [Statically define to be enabled to harmonize barebox' & dt-utils' code base.])
 
+AC_DEFINE(CONFIG_TEST_LOOPBACK, [0], [Only enabled in meson for testing.])
+
 AC_CHECK_FUNCS([__secure_getenv secure_getenv])
 
 my_CFLAGS="-Wall \
diff --git a/meson.build b/meson.build
index 1bc32274af07..be92446f137a 100644
--- a/meson.build
+++ b/meson.build
@@ -21,6 +21,7 @@ conf.set10('CONFIG_MTD', true)
 conf.set10('CONFIG_STATE', true)
 conf.set10('CONFIG_STATE_BACKWARD_COMPATIBLE', get_option('state-backward-compatibility'))
 conf.set10('CONFIG_LOCK_DEVICE_NODE', get_option('lock-device'))
+conf.set10('CONFIG_TEST_LOOPBACK', get_option('tests'))
 
 meson.add_dist_script(
   find_program('check-news.sh').path(),
diff --git a/src/dt/dt.h b/src/dt/dt.h
index a4213d49606a..153b56e09a21 100644
--- a/src/dt/dt.h
+++ b/src/dt/dt.h
@@ -220,7 +220,6 @@ extern int of_set_root_node(struct device_node *node);
 extern int of_platform_populate(struct device_node *root,
 				const struct of_device_id *matches,
 				struct device_d *parent);
-extern struct device_d *of_find_device_by_node(struct device_node *np);
 
 int of_device_is_stdout_path(struct device_d *dev);
 const char *of_get_model(void);
diff --git a/src/libdt.c b/src/libdt.c
index af28de6f17c6..7c24c9197c7f 100644
--- a/src/libdt.c
+++ b/src/libdt.c
@@ -2091,6 +2091,22 @@ struct udev_of_path {
 
 static LIST_HEAD(udev_of_devices);
 
+static const char *udev_device_get_of_path(struct udev_device *dev)
+{
+	const char *of_path;
+
+	of_path = udev_device_get_property_value(dev, "OF_FULLNAME");
+	if (of_path)
+		return of_path;
+
+	if (IS_ENABLED(CONFIG_TEST_LOOPBACK) &&
+	    !strcmp(udev_device_get_subsystem(dev), "block") &&
+	    !strncmp(udev_device_get_sysname(dev), "loop", 4))
+		return udev_device_get_sysname(dev);
+
+	return NULL;
+}
+
 static void of_scan_udev_devices(void)
 {
 	struct udev *udev;
@@ -2111,6 +2127,8 @@ static void of_scan_udev_devices(void)
 	udev_enumerate_add_match_subsystem(enumerate, "spi");
 	udev_enumerate_add_match_subsystem(enumerate, "mtd");
 	udev_enumerate_add_match_subsystem(enumerate, "amba");
+	if (IS_ENABLED(CONFIG_TEST_LOOPBACK))
+		udev_enumerate_add_match_subsystem(enumerate, "block");
 	udev_enumerate_scan_devices(enumerate);
 	devices = udev_enumerate_get_list_entry(enumerate);
 
@@ -2124,7 +2142,7 @@ static void of_scan_udev_devices(void)
 		path = udev_list_entry_get_name(dev_list_entry);
 		dev = udev_device_new_from_syspath(udev, path);
 
-		of_path = udev_device_get_property_value(dev, "OF_FULLNAME");
+		of_path = udev_device_get_of_path(dev);
 		if (!of_path)
 			continue;
 
@@ -2148,11 +2166,37 @@ struct udev_device *of_find_device_by_node_path(const char *of_full_path)
 			ret = udev_of_path->udev;
 			break;
 		}
+		if (!strcmp(udev_of_path->of_path, of_full_path)) {
+			ret = udev_of_path->udev;
+			break;
+		}
 	}
 
 	return ret;
 }
 
+static struct udev_device *of_find_device_by_node(struct device_node *np)
+{
+	struct udev_of_path *udev_of_path;
+	struct udev_device *dev;
+	const char *filename;
+
+	dev = of_find_device_by_node_path(np->full_name);
+	if (dev)
+		return dev;
+
+	if (IS_ENABLED(CONFIG_TEST_LOOPBACK) &&
+	    !of_property_read_string(np, "barebox,filename", &filename) &&
+	    !strncmp(filename, "/dev/", 5)) {
+		list_for_each_entry(udev_of_path, &udev_of_devices, list) {
+			if (!strcmp(udev_of_path->of_path, filename + 5))
+				return udev_of_path->udev;
+		}
+	}
+
+	return NULL;
+}
+
 static struct udev_device *device_find_mtd_partition(struct udev_device *dev,
 		const char *name)
 {
@@ -2546,7 +2590,7 @@ static int __of_cdev_find(struct device_node *partition_node, struct cdev *cdev)
 	 * 42e9401bd146 ("mtd: Add partition device node to mtd partition
 	 * devices").
 	 */
-	dev = of_find_device_by_node_path(partition_node->full_name);
+	dev = of_find_device_by_node(partition_node);
 	if (dev) {
 		if (udev_device_is_eeprom(dev))
 			return udev_parse_eeprom(dev, &cdev->devpath);
@@ -2619,7 +2663,7 @@ static int __of_cdev_find(struct device_node *partition_node, struct cdev *cdev)
 		}
 	}
 	else {
-		dev = of_find_device_by_node_path(node->full_name);
+		dev = of_find_device_by_node(node);
 		if (!dev) {
 			fprintf(stderr, "%s: cannot find device from node %s\n", __func__,
 					node->full_name);
-- 
2.39.2