libsync: move kernel headers for sync ioctls to sync.h

This patch moves the legacy API to the internal sync.h header
and add documentation to it.

Test: Sync unit tests still passes.
Change-Id: I9b17eb23af30043b3df5fb9e857affad68ba8521

libsync/include/sync/sync.h

@@ -22,9 +22,16 @@
 #include <sys/cdefs.h>
 #include <stdint.h>
 
+#include <linux/types.h>
+
 __BEGIN_DECLS
 
-// XXX: These structs are copied from the header "linux/sync.h".
+struct sync_legacy_merge_data {
+ int32_t fd2;
+ char name[32];
+ int32_t fence;
+};
+
 struct sync_fence_info_data {
  uint32_t len;
  char name[32];
@@ -41,6 +48,48 @@ struct sync_pt_info {
  uint8_t driver_data[0];
 };
 
+#define SYNC_IOC_MAGIC		'>'
+
+/**
+ * DOC: SYNC_IOC_LEGACY_WAIT - wait for a fence to signal
+ *
+ * pass timeout in milliseconds.  Waits indefinitely timeout < 0.
+ *
+ * This is the legacy version of the Sync API before the de-stage that happened
+ * on Linux kernel 4.7.
+ */
+#define SYNC_IOC_LEGACY_WAIT	_IOW(SYNC_IOC_MAGIC, 0, __s32)
+
+/**
+ * DOC: SYNC_IOC_MERGE - merge two fences
+ *
+ * Takes a struct sync_merge_data.  Creates a new fence containing copies of
+ * the sync_pts in both the calling fd and sync_merge_data.fd2.  Returns the
+ * new fence's fd in sync_merge_data.fence
+ *
+ * This is the legacy version of the Sync API before the de-stage that happened
+ * on Linux kernel 4.7.
+ */
+#define SYNC_IOC_LEGACY_MERGE	_IOWR(SYNC_IOC_MAGIC, 1, \
+	struct sync_legacy_merge_data)
+
+/**
+ * DOC: SYNC_IOC_LEGACY_FENCE_INFO - get detailed information on a fence
+ *
+ * Takes a struct sync_fence_info_data with extra space allocated for pt_info.
+ * Caller should write the size of the buffer into len.  On return, len is
+ * updated to reflect the total size of the sync_fence_info_data including
+ * pt_info.
+ *
+ * pt_info is a buffer containing sync_pt_infos for every sync_pt in the fence.
+ * To iterate over the sync_pt_infos, use the sync_pt_info.len field.
+ *
+ * This is the legacy version of the Sync API before the de-stage that happened
+ * on Linux kernel 4.7.
+ */
+#define SYNC_IOC_LEGACY_FENCE_INFO	_IOWR(SYNC_IOC_MAGIC, 2,\
+	struct sync_fence_info_data)
+
 /* timeout in msecs */
 int sync_wait(int fd, int timeout);
 int sync_merge(const char *name, int fd1, int fd2);

libsync/sync.c

@@ -27,18 +27,6 @@
 
 #include <sync/sync.h>
 
-// The sync code is undergoing a major change. Add enough in to get
-// everything to compile wih the latest uapi headers.
-struct sync_merge_data {
-  int32_t fd2;
-  char name[32];
-  int32_t fence;
-};
-
-#define SYNC_IOC_MAGIC '>'
-#define SYNC_IOC_WAIT _IOW(SYNC_IOC_MAGIC, 0, __s32)
-#define SYNC_IOC_MERGE _IOWR(SYNC_IOC_MAGIC, 1, struct sync_merge_data)
-#define SYNC_IOC_FENCE_INFO _IOWR(SYNC_IOC_MAGIC, 2, struct sync_fence_info_data)
 
 struct sw_sync_create_fence_data {
   __u32 value;
@@ -54,18 +42,18 @@ int sync_wait(int fd, int timeout)
 {
     __s32 to = timeout;
 
-    return ioctl(fd, SYNC_IOC_WAIT, &to);
+    return ioctl(fd, SYNC_IOC_LEGACY_WAIT, &to);
 }
 
 int sync_merge(const char *name, int fd1, int fd2)
 {
-    struct sync_merge_data data;
+    struct sync_legacy_merge_data data;
     int err;
 
     data.fd2 = fd2;
     strlcpy(data.name, name, sizeof(data.name));
 
-    err = ioctl(fd1, SYNC_IOC_MERGE, &data);
+    err = ioctl(fd1, SYNC_IOC_LEGACY_MERGE, &data);
     if (err < 0)
         return err;
 
@@ -82,7 +70,7 @@ struct sync_fence_info_data *sync_fence_info(int fd)
         return NULL;
 
     info->len = 4096;
-    err = ioctl(fd, SYNC_IOC_FENCE_INFO, info);
+    err = ioctl(fd, SYNC_IOC_LEGACY_FENCE_INFO, info);
     if (err < 0) {
         free(info);
         return NULL;