2 files changed, 158 insertions, 0 deletions
diff --git a/backend/drm/drm-properties.c b/backend/drm/drm-properties.c
new file mode 100644
index 00000000..3e089c31
--- /dev/null
+++ b/backend/drm/drm-properties.c
@@ -0,0 +1,99 @@
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <xf86drm.h>
+#include <xf86drmMode.h>
+#include <wlr/util/log.h>
+#include "drm-properties.h"
+
+/*
+ * Creates a mapping between property names and an array index where to store
+ * the ids.  The prop_info arrays must be sorted by name, as bsearch is used to
+ * search them.
+ */
+struct prop_info {
+	const char *name;
+	size_t index;
+};
+
+static const struct prop_info connector_info[] = {
+#define INDEX(name) (offsetof(union wlr_drm_connector_props, name) / sizeof(uint32_t))
+	{ "CRTC_ID", INDEX(crtc_id) },
+	{ "DPMS",    INDEX(dpms) },
+	{ "EDID",    INDEX(edid) },
+#undef INDEX
+};
+
+static const struct prop_info crtc_info[] = {
+#define INDEX(name) (offsetof(union wlr_drm_crtc_props, name) / sizeof(uint32_t))
+	{ "rotation",  INDEX(rotation) },
+	{ "scaling mode", INDEX(scaling_mode) },
+#undef INDEX
+};
+
+static const struct prop_info plane_info[] = {
+#define INDEX(name) (offsetof(union wlr_drm_plane_props, name) / sizeof(uint32_t))
+	{ "CRTC_H",  INDEX(crtc_h) },
+	{ "CRTC_ID", INDEX(crtc_id) },
+	{ "CRTC_W",  INDEX(crtc_w) },
+	{ "CRTC_X",  INDEX(crtc_x) },
+	{ "CRTC_Y",  INDEX(crtc_y) },
+	{ "FB_ID",   INDEX(fb_id) },
+	{ "SRC_H",   INDEX(src_h) },
+	{ "SRC_W",   INDEX(src_w) },
+	{ "SRC_X",   INDEX(src_x) },
+	{ "SRC_Y",   INDEX(src_y) },
+	{ "type",    INDEX(type) },
+#undef INDEX
+};
+
+static int cmp_prop_info(const void *arg1, const void *arg2) {
+	const struct prop_info *a = arg1;
+	const struct prop_info *b = arg2;
+
+	return strcmp(a->name, b->name);
+}
+
+static bool scan_properties(int fd, uint32_t id, uint32_t type, uint32_t *result,
+		const struct prop_info *info, size_t info_len) {
+	drmModeObjectProperties *props = drmModeObjectGetProperties(fd, id, type);
+	if (!props) {
+		wlr_log_errno(L_ERROR, "Failed to get DRM object properties");
+		return false;
+	}
+
+	for (uint32_t i = 0; i < props->count_props; ++i) {
+		drmModePropertyRes *prop = drmModeGetProperty(fd, props->props[i]);
+		if (!prop) {
+			wlr_log_errno(L_ERROR, "Failed to get DRM object property");
+			continue;
+		}
+
+		const struct prop_info *p =
+			bsearch(prop->name, info, info_len, sizeof(info[0]), cmp_prop_info);
+		if (p) {
+			result[p->index] = prop->prop_id;
+		}
+
+		drmModeFreeProperty(prop);
+	}
+
+	drmModeFreeObjectProperties(props);
+	return true;
+}
+
+bool wlr_drm_get_connector_props(int fd, uint32_t id, union wlr_drm_connector_props *out) {
+	return scan_properties(fd, id, DRM_MODE_OBJECT_CONNECTOR, out->props,
+		connector_info, sizeof(connector_info) / sizeof(connector_info[0]));
+}
+
+bool wlr_drm_get_crtc_props(int fd, uint32_t id, union wlr_drm_crtc_props *out) {
+	return scan_properties(fd, id, DRM_MODE_OBJECT_CRTC, out->props,
+		crtc_info, sizeof(crtc_info) / sizeof(crtc_info[0]));
+}
+
+bool wlr_drm_get_plane_props(int fd, uint32_t id, union wlr_drm_plane_props *out) {
+	return scan_properties(fd, id, DRM_MODE_OBJECT_PLANE, out->props,
+		plane_info, sizeof(plane_info) / sizeof(plane_info[0]));
+}
diff --git a/backend/drm/drm-properties.h b/backend/drm/drm-properties.h
new file mode 100644
index 00000000..99791958
--- /dev/null
+++ b/backend/drm/drm-properties.h
@@ -0,0 +1,59 @@
+#ifndef DRM_PROPERTIES_H
+#define DRM_PROPERTIES_H
+
+#include <stdbool.h>
+#include <stdint.h>
+
+/*
+ * These types contain the property ids for several DRM objects.
+ * See https://01.org/linuxgraphics/gfx-docs/drm/drm-kms-properties.html
+ * for more details.
+ */
+
+union wlr_drm_connector_props {
+	struct {
+		uint32_t edid;
+		uint32_t dpms;
+
+		// atomic-modesetting only
+
+		uint32_t crtc_id;
+	};
+	uint32_t props[3];
+};
+
+union wlr_drm_crtc_props {
+	struct {
+		// Neither of these are guranteed to exist
+		uint32_t rotation;
+		uint32_t scaling_mode;
+	};
+	uint32_t props[2];
+};
+
+union wlr_drm_plane_props {
+	struct {
+		uint32_t type;
+		uint32_t rotation; // Not guranteed to exist
+
+		// atomic-modesetting only
+
+		uint32_t src_x;
+		uint32_t src_y;
+		uint32_t src_w;
+		uint32_t src_h;
+		uint32_t crtc_x;
+		uint32_t crtc_y;
+		uint32_t crtc_w;
+		uint32_t crtc_h;
+		uint32_t fb_id;
+		uint32_t crtc_id;
+	};
+	uint32_t props[12];
+};
+
+bool wlr_drm_get_connector_props(int fd, uint32_t id, union wlr_drm_connector_props *out);
+bool wlr_drm_get_crtc_props(int fd, uint32_t id, union wlr_drm_crtc_props *out);
+bool wlr_drm_get_plane_props(int fd, uint32_t id, union wlr_drm_plane_props *out);
+
+#endif