[igt-dev] [PATCH i-g-t 1/7] lib/debugfs: GT directory helpers

[Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>]

From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

Add two debugfs helpers to be used for opening per-gt debugfs directories.

Note: This likely needs updating once the final debugfs layout is set.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
---
 lib/igt_debugfs.c | 60 +++++++++++++++++++++++++++++++++++++++++++++++
 lib/igt_debugfs.h |  4 ++++
 2 files changed, 64 insertions(+)

diff --git a/lib/igt_debugfs.c b/lib/igt_debugfs.c
index 05889bbe..afde2da6 100644
--- a/lib/igt_debugfs.c
+++ b/lib/igt_debugfs.c
@@ -217,6 +217,37 @@ int igt_debugfs_dir(int device)
 	return open(path, O_RDONLY);
 }
 
+/**
+ * igt_debugfs_gt_dir:
+ * @device: fd of the device
+ * @gt: GT instance number
+ *
+ * This opens the debugfs directory corresponding to device for use
+ * with igt_sysfs_get() and related functions.
+ *
+ * Returns:
+ * The directory fd, or -1 on failure.
+ */
+int igt_debugfs_gt_dir(int device, unsigned int gt)
+{
+	int debugfs_gt_dir_fd;
+	char path[PATH_MAX];
+	char gtpath[16];
+	int ret;
+
+	if (!igt_debugfs_path(device, path, sizeof(path)))
+		return -1;
+
+	ret = snprintf(gtpath, sizeof(gtpath), "/gt%u", gt);
+	igt_assert(ret < sizeof(gtpath));
+	strncat(path, gtpath, sizeof(path) - 1);
+
+	debugfs_gt_dir_fd = open(path, O_RDONLY);
+	igt_debug_on_f(debugfs_gt_dir_fd < 0, "path: %s\n", path);
+
+	return debugfs_gt_dir_fd;
+}
+
 /**
  * igt_debugfs_connector_dir:
  * @device: fd of the device
@@ -313,6 +344,35 @@ bool igt_debugfs_exists(int device, const char *filename, int mode)
 	return false;
 }
 
+/**
+ * igt_debugfs_gt_open:
+ * @device: open i915 drm fd
+ * @gt: gt instance number
+ * @filename: name of the debugfs node to open
+ * @mode: mode bits as used by open()
+ *
+ * This opens a debugfs file as a Unix file descriptor. The filename should be
+ * relative to the drm device's root, i.e. without "drm/$minor".
+ *
+ * Returns:
+ * The Unix file descriptor for the debugfs file or -1 if that didn't work out.
+ */
+int
+igt_debugfs_gt_open(int device, unsigned int gt, const char *filename, int mode)
+{
+	int dir, ret;
+
+	dir = igt_debugfs_gt_dir(device, gt);
+	if (dir < 0)
+		return dir;
+
+	ret = openat(dir, filename, mode);
+
+	close(dir);
+
+	return ret;
+}
+
 /**
  * igt_debugfs_simple_read:
  * @dir: fd of the debugfs directory
diff --git a/lib/igt_debugfs.h b/lib/igt_debugfs.h
index 4824344a..3e6194ad 100644
--- a/lib/igt_debugfs.h
+++ b/lib/igt_debugfs.h
@@ -45,6 +45,10 @@ void __igt_debugfs_write(int fd, const char *filename, const char *buf, int size
 int igt_debugfs_simple_read(int dir, const char *filename, char *buf, int size);
 bool igt_debugfs_search(int fd, const char *filename, const char *substring);
 
+int igt_debugfs_gt_dir(int device, unsigned int gt);
+int igt_debugfs_gt_open(int device, unsigned int gt, const char *filename,
+			int mode);
+
 /**
  * igt_debugfs_read:
  * @filename: name of the debugfs file
-- 
2.36.1