[PATCH i-g-t 2/5] lib/igt_configfs: Add helper to mount configfs

[Riana Tauro]

From: José Expósito <jose.exposito89 at gmail.com>

Add a new helper function to mount and open configfs

Co-developed-by: Jim Shargo <jshargo at chromium.org>
Signed-off-by: Jim Shargo <jshargo at chromium.org>
Co-developed-by: Marius Vlad <marius.vlad at collabora.com>
Signed-off-by: Marius Vlad <marius.vlad at collabora.com>
Co-developed-by: Riana Tauro <riana.tauro at intel.com>
Signed-off-by: Riana Tauro <riana.tauro at intel.com>
Signed-off-by: José Expósito <jose.exposito89 at gmail.com>
---
 lib/igt.h          |  1 +
 lib/igt_configfs.c | 82 ++++++++++++++++++++++++++++++++++++++++++++++
 lib/igt_configfs.h | 15 +++++++++
 lib/meson.build    |  1 +
 4 files changed, 99 insertions(+)
 create mode 100644 lib/igt_configfs.c
 create mode 100644 lib/igt_configfs.h

diff --git a/lib/igt.h b/lib/igt.h
index 58c39e098..173ca70bf 100644
--- a/lib/igt.h
+++ b/lib/igt.h
@@ -27,6 +27,7 @@
 #include "drmtest.h"
 #include "i915_3d.h"
 #include "igt_aux.h"
+#include "igt_configfs.h"
 #include "igt_core.h"
 #include "igt_debugfs.h"
 #include "igt_draw.h"
diff --git a/lib/igt_configfs.c b/lib/igt_configfs.c
new file mode 100644
index 000000000..6b202b76f
--- /dev/null
+++ b/lib/igt_configfs.c
@@ -0,0 +1,82 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2023 Google LLC.
+ * Copyright © 2023 Collabora, Ltd.
+ * Copyright © 2024 Red Hat, Inc.
+ * Copyright © 2025 Intel Corporation
+ */
+
+#include <sys/mount.h>
+#include <fcntl.h>
+#include <limits.h>
+
+#include "igt_aux.h"
+#include "igt_configfs.h"
+
+/**
+ * SECTION:igt_configfs
+ * @short_description: Support code for configfs features
+ * @title: configfs
+ * @include: igt_configfs.h
+ *
+ * This library provides helpers to access configfs features.
+ */
+
+/*
+ * General configfs helpers
+ */
+
+static const char *__igt_configfs_mount(void)
+{
+	if (igt_is_mountpoint("/sys/kernel/config"))
+		return "/sys/kernel/config";
+
+	if (igt_is_mountpoint("/config"))
+		return "/config";
+
+	if (mount("config", "/sys/kernel/config", "configfs", 0, 0))
+		return NULL;
+
+	return "/sys/kernel/config";
+}
+
+/**
+ * igt_configfs_mount:
+ *
+ * This attempts to locate where configfs is mounted on the filesystem,
+ * and if not found, will then try to mount configfs at /sys/kernel/config.
+ *
+ * Returns:
+ * The path to the configfs mount point (e.g. /sys/kernel/config)
+ */
+const char *igt_configfs_mount(void)
+{
+	static const char *path;
+
+	if (!path)
+		path = __igt_configfs_mount();
+
+	return path;
+}
+
+/**
+ * igt_configfs_open: open configfs path
+ * @name: name of the configfs directory
+ *
+ * Opens the configfs directory corresponding to the name
+ *
+ * Returns:
+ * The directory fd, or -1 on failure.
+ */
+int igt_configfs_open(const char *name)
+{
+	char path[PATH_MAX];
+	const char *configfs_path;
+
+	configfs_path = igt_configfs_mount();
+	igt_assert(configfs_path);
+
+	snprintf(path, sizeof(path), "%s/%s", configfs_path, name);
+
+	return open(path, O_RDONLY);
+}
diff --git a/lib/igt_configfs.h b/lib/igt_configfs.h
new file mode 100644
index 000000000..91f95659b
--- /dev/null
+++ b/lib/igt_configfs.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * Copyright © 2023 Google LLC.
+ * Copyright © 2023 Collabora, Ltd.
+ * Copyright © 2024 Red Hat, Inc.
+ * Copyright © 2025 Intel Corporation
+ */
+
+#ifndef __IGT_CONFIGFS_H__
+#define __IGT_CONFIGFS_H__
+
+const char *igt_configfs_mount(void);
+int igt_configfs_open(const char *name);
+
+#endif /* __IGT_CONFIGFS_H__ */
diff --git a/lib/meson.build b/lib/meson.build
index 8517cd540..59072d8ce 100644
--- a/lib/meson.build
+++ b/lib/meson.build
@@ -18,6 +18,7 @@ lib_sources = [
 	'i915/i915_crc.c',
 	'igt_collection.c',
 	'igt_color_encoding.c',
+	'igt_configfs.c',
 	'igt_facts.c',
 	'igt_crc.c',
 	'igt_debugfs.c',
-- 
2.47.1