tools: ffs-test: convert to new descriptor format fixing compilation error

Commit [ac8dde11: “usb: gadget: f_fs: Add flags to descriptors block”]
which introduced a new descriptor format for FunctionFS removed the
usb_functionfs_descs_head structure, which is still used by ffs-test.
tool.

Convert ffs-test by converting it to use the new header format.  For
testing kernels prior to 3.14 (when the new format was introduced) and
parsing of the legacy headers in the new kernels, provide a compilation
flag to make the tool use the old format.

Finally, include information as to when the legacy FunctionFS headers
format has been deprecated (which is also when the new one has been
introduced).
Reported-by: Lad, Prabhakar <prabhakar.csengg@gmail.com>
Signed-off-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

include/uapi/linux/usb/functionfs.h

@@ -53,7 +53,7 @@ struct usb_endpoint_descriptor_no_audio {
  * structure.  Any flags that are not recognised cause the whole block to be
  * rejected with -ENOSYS.
  *
- * Legacy descriptors format:
+ * Legacy descriptors format (deprecated as of 3.14):
  *
  * | off | name      | type         | description                          |
  * |-----+-----------+--------------+--------------------------------------|

tools/usb/Makefile

@@ -6,7 +6,11 @@ WARNINGS = -Wall -Wextra
 CFLAGS = $(WARNINGS) -g -I../include
 LDFLAGS = $(PTHREAD_LIBS)
 
-all: testusb ffs-test
+all: testusb ffs-test ffs-test-legacy
+
+ffs-test-legacy: ffs-test.c
+	$(CC) $(CFLAGS) -o $@ $^ $(LDFLAGS) -DUSE_LEGACY_DESC_HEAD
+
 %: %.c
 	$(CC) $(CFLAGS) -o $@ $^ $(LDFLAGS)
 

tools/usb/ffs-test.c

 /*
- * ffs-test.c.c -- user mode filesystem api for usb composite function
+ * ffs-test.c -- user mode filesystem api for usb composite function
  *
  * Copyright (C) 2010 Samsung Electronics
  *                    Author: Michal Nazarewicz <mina86@mina86.com>
@@ -21,6 +21,8 @@
 
 /* $(CROSS_COMPILE)cc -Wall -Wextra -g -o ffs-test ffs-test.c -lpthread */
 
+/* Uncomment to make the tool use legacy FFS descriptor headers. */
+/* #define USE_LEGACY_DESC_HEAD */
 
 #define _BSD_SOURCE /* for endian.h */
 
@@ -106,7 +108,15 @@ static void _msg(unsigned level, const char *fmt, ...)
 /******************** Descriptors and Strings *******************************/
 
 static const struct {
-	struct usb_functionfs_descs_head header;
+	struct {
+		__le32 magic;
+		__le32 length;
+#ifndef USE_LEGACY_DESC_HEAD
+		__le32 flags;
+#endif
+		__le32 fs_count;
+		__le32 hs_count;
+	} __attribute__((packed)) header;
 	struct {
 		struct usb_interface_descriptor intf;
 		struct usb_endpoint_descriptor_no_audio sink;
@@ -114,7 +124,13 @@ static const struct {
 	} __attribute__((packed)) fs_descs, hs_descs;
 } __attribute__((packed)) descriptors = {
 	.header = {
+#ifdef USE_LEGACY_DESC_HEAD
 		.magic = cpu_to_le32(FUNCTIONFS_DESCRIPTORS_MAGIC),
+#else
+		.magic = cpu_to_le32(FUNCTIONFS_DESCRIPTORS_MAGIC_V2),
+		.flags = cpu_to_le32(FUNCTIONFS_HAS_FS_DESC |
+				     FUNCTIONFS_HAS_HS_DESC),
+#endif
 		.length = cpu_to_le32(sizeof descriptors),
 		.fs_count = 3,
 		.hs_count = 3,