[PATCH v7 4/5] lib/igt_sysfs: add helpers to access engine sysfs directory

[Andrzej Hajda <andrzej.hajda@intel.com>]

Helpers follow convention of xe_sysfs_gt_(path|open).

v7:
  - staticize local const array

Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
---
 lib/igt_sysfs.c | 71 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 lib/igt_sysfs.h |  3 +++
 2 files changed, 74 insertions(+)

diff --git a/lib/igt_sysfs.c b/lib/igt_sysfs.c
index 0c5817eb1580..90b923a99a26 100644
--- a/lib/igt_sysfs.c
+++ b/lib/igt_sysfs.c
@@ -40,7 +40,9 @@
 #include <dirent.h>
 #include <unistd.h>
 #include <fcntl.h>
+#include <xe_drm.h>
 
+#include "drmtest.h"
 #include "igt_core.h"
 #include "igt_sysfs.h"
 #include "igt_device.h"
@@ -263,6 +265,75 @@ int xe_sysfs_gt_open(int xe_device, int gt)
 	return open(path, O_RDONLY);
 }
 
+static const char *engine_class_to_str(__u16 class)
+{
+	static const char * const str[] = {
+		[DRM_XE_ENGINE_CLASS_RENDER] = "rcs",
+		[DRM_XE_ENGINE_CLASS_COPY] = "bcs",
+		[DRM_XE_ENGINE_CLASS_VIDEO_DECODE] = "vcs",
+		[DRM_XE_ENGINE_CLASS_VIDEO_ENHANCE] = "vecs",
+		[DRM_XE_ENGINE_CLASS_COMPUTE] = "ccs",
+	};
+
+	if (class < ARRAY_SIZE(str))
+		return str[class];
+
+	return "unk";
+}
+
+/**
+ * xe_sysfs_engine_path:
+ * @xe_device: fd of the device
+ * @gt: gt number
+ * @class: engine class
+ * @path: buffer to fill with the sysfs gt path to the device
+ * @pathlen: length of @path buffer
+ *
+ * Returns:
+ * The directory path, or NULL on failure.
+ */
+char *
+xe_sysfs_engine_path(int xe_device, int gt, int class, char *path, int pathlen)
+{
+	struct stat st;
+	int tile = IS_PONTEVECCHIO(intel_get_drm_devid(xe_device)) ? gt : 0;
+
+	if (xe_device < 0)
+		return NULL;
+
+	if (igt_debug_on(fstat(xe_device, &st)) || igt_debug_on(!S_ISCHR(st.st_mode)))
+		return NULL;
+
+	snprintf(path, pathlen, "/sys/dev/char/%d:%d/device/tile%d/gt%d/engines/%s",
+		 major(st.st_rdev), minor(st.st_rdev), tile, gt, engine_class_to_str(class));
+
+	if (!access(path, F_OK))
+		return path;
+
+	return NULL;
+}
+
+/**
+ * xe_sysfs_engine_open:
+ * @xe_device: fd of the device
+ * @gt: gt number
+ * @class: engine class
+ *
+ * This opens the sysfs gt directory corresponding to device and tile for use
+ *
+ * Returns:
+ * The directory fd, or -1 on failure.
+ */
+int xe_sysfs_engine_open(int xe_device, int gt, int class)
+{
+	char path[96];
+
+	if (!xe_sysfs_engine_path(xe_device, gt, class, path, sizeof(path)))
+		return -1;
+
+	return open(path, O_RDONLY);
+}
+
 /**
  * igt_sysfs_gt_path:
  * @device: fd of the device
diff --git a/lib/igt_sysfs.h b/lib/igt_sysfs.h
index f37d80ec130e..6c604d939013 100644
--- a/lib/igt_sysfs.h
+++ b/lib/igt_sysfs.h
@@ -166,4 +166,7 @@ int xe_sysfs_gt_open(int xe_device, int gt);
 char *xe_sysfs_tile_path(int xe_device, int tile, char *path, int pathlen);
 int xe_sysfs_tile_open(int xe_device, int tile);
 int xe_sysfs_get_num_tiles(int xe_device);
+char *xe_sysfs_engine_path(int xe_device, int gt, int class, char *path, int pathlen);
+int xe_sysfs_engine_open(int xe_device, int gt, int class);
+
 #endif /* __IGT_SYSFS_H__ */

-- 
2.34.1