xf86drm: add iterator API for DRM/KMS IN_FORMATS blobs

Add support for parsing IN_FORMATS property blobs. Providing libdrm
with this functionality helps to standardise how user-space reads
kernel blobs and decreases duplication on the client side.

drmModeFormatModifierBlobIterNext() allows the caller to view
formats and associated modifiers given a valid property blob.
An example is available inside the libdrm unit test, modetest.c.

Signed-off-by: Luigi Santivetti <luigi.santivetti@imgtec.com>
Reviewed-by: Simon Ser <contact@emersion.fr>

1 files changed, 9 insertions, 0 deletions

diff --git a/xf86drmMode.h b/xf86drmMode.h
index de0e2fdb..19bf91dd 100644
--- a/xf86drmMode.h
+++ b/xf86drmMode.h
@@ -42,6 +42,7 @@ extern "C" {
 
 #include <drm.h>
 #include <drm_mode.h>
+#include <stdbool.h>
 #include <stddef.h>
 #include <stdint.h>
 
@@ -231,6 +232,12 @@ typedef struct _drmModeObjectProperties {
 	uint64_t *prop_values;
 } drmModeObjectProperties, *drmModeObjectPropertiesPtr;
 
+typedef struct _drmModeFormatModifierIterator {
+	uint32_t fmt_idx, mod_idx;
+	uint32_t fmt;
+	uint64_t mod;
+} drmModeFormatModifierIterator;
+
 typedef struct _drmModePlane {
 	uint32_t count_formats;
 	uint32_t *formats;
@@ -388,6 +395,8 @@ extern drmModePropertyPtr drmModeGetProperty(int fd, uint32_t propertyId);
 extern void drmModeFreeProperty(drmModePropertyPtr ptr);
 
 extern drmModePropertyBlobPtr drmModeGetPropertyBlob(int fd, uint32_t blob_id);
+extern bool drmModeFormatModifierBlobIterNext(const drmModePropertyBlobRes *blob,
+					      drmModeFormatModifierIterator *iter);
 extern void drmModeFreePropertyBlob(drmModePropertyBlobPtr ptr);
 extern int drmModeConnectorSetProperty(int fd, uint32_t connector_id, uint32_t property_id,
 				    uint64_t value);