[PATCH] tools: usb: ffs-aio-example: Fix build error with aarch64-*-gnu-gcc toolchain(s)

[Bhupesh Sharma]

The tools/usb/aio_simple.c file when cross-compiled with
aarch64-*-gnu-gcc toolchain(s) leads to the following errors:

  aio_simple.c:30:10: fatal error: endian.h: No such file or directory
  30 | #include <endian.h>
      |          ^~~~~~~~~~

  aio_simple.c:88:14: note: (near initialization for
                      'descriptors.fs_count')
  aio_simple.c:110:14: error: initializer element is not constant
  110 |  .hs_count = htole32(3),
      |              ^~~~~~~
  aio_simple.c:110:14: note: (near initialization for
                      'descriptors.hs_count')
  aio_simple.c:124:22: error: initializer element is not constant
  124 |    .wMaxPacketSize = htole16(512),
      |                      ^~~~~~~
  aio_simple.c:124:22: note: (near initialization for
                       'descriptors.hs_descs.bulk_sink.wMaxPacketSize')

Fix these compilation issues by:
 - Switching to _DEFAULT_SOURCE:
    _BSD_SOURCE is deprecated and gives a build warning. Let's use
    _DEFAULT_SOURCE instead.
 - Currently this file uses library htole16/32 function calls.
   Replace these with equivalent 'cpu_to_le16/32' calls.

Cc: Felipe Balbi <balbi@xxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Bhupesh Sharma <bhupesh.sharma@xxxxxxxxxx>
---
 .../simple/device_app/aio_simple.c            | 44 +++++++++++++------
 1 file changed, 31 insertions(+), 13 deletions(-)

diff --git a/tools/usb/ffs-aio-example/simple/device_app/aio_simple.c b/tools/usb/ffs-aio-example/simple/device_app/aio_simple.c
index 1f44a29818bf..96616eb4600b 100644
--- a/tools/usb/ffs-aio-example/simple/device_app/aio_simple.c
+++ b/tools/usb/ffs-aio-example/simple/device_app/aio_simple.c
@@ -25,7 +25,9 @@
  * For more information, please refer to <http://unlicense.org/>
  */
 
-#define _BSD_SOURCE /* for endian.h */
+/* $(CROSS_COMPILE)cc -g -o aio_simple aio_simple.c -laio */
+
+#define _DEFAULT_SOURCE /* for endian.h */
 
 #include <endian.h>
 #include <errno.h>
@@ -49,6 +51,22 @@
 
 #define BUF_LEN		8192
 
+/*
+ * cpu_to_le16/32 are used when initializing structures, a context where a
+ * function call is not allowed. To solve this, we code cpu_to_le16/32 in a way
+ * that allows them to be used when initializing structures.
+ */
+
+#if BYTE_ORDER == __LITTLE_ENDIAN
+#define cpu_to_le16(x)  (x)
+#define cpu_to_le32(x)  (x)
+#else
+#define cpu_to_le16(x)  ((((x) >> 8) & 0xffu) | (((x) & 0xffu) << 8))
+#define cpu_to_le32(x)  \
+	((((x) & 0xff000000u) >> 24) | (((x) & 0x00ff0000u) >>  8) | \
+	(((x) & 0x0000ff00u) <<  8) | (((x) & 0x000000ffu) << 24))
+#endif
+
 /******************** Descriptors and Strings *******************************/
 
 static const struct {
@@ -62,12 +80,12 @@ static const struct {
 	} __attribute__ ((__packed__)) fs_descs, hs_descs;
 } __attribute__ ((__packed__)) descriptors = {
 	.header = {
-		.magic = htole32(FUNCTIONFS_DESCRIPTORS_MAGIC_V2),
-		.flags = htole32(FUNCTIONFS_HAS_FS_DESC |
+		.magic = cpu_to_le32(FUNCTIONFS_DESCRIPTORS_MAGIC_V2),
+		.flags = cpu_to_le32(FUNCTIONFS_HAS_FS_DESC |
 				     FUNCTIONFS_HAS_HS_DESC),
-		.length = htole32(sizeof(descriptors)),
+		.length = cpu_to_le32(sizeof(descriptors)),
 	},
-	.fs_count = htole32(3),
+	.fs_count = cpu_to_le32(3),
 	.fs_descs = {
 		.intf = {
 			.bLength = sizeof(descriptors.fs_descs.intf),
@@ -89,7 +107,7 @@ static const struct {
 			.bmAttributes = USB_ENDPOINT_XFER_BULK,
 		},
 	},
-	.hs_count = htole32(3),
+	.hs_count = cpu_to_le32(3),
 	.hs_descs = {
 		.intf = {
 			.bLength = sizeof(descriptors.hs_descs.intf),
@@ -103,14 +121,14 @@ static const struct {
 			.bDescriptorType = USB_DT_ENDPOINT,
 			.bEndpointAddress = 1 | USB_DIR_IN,
 			.bmAttributes = USB_ENDPOINT_XFER_BULK,
-			.wMaxPacketSize = htole16(512),
+			.wMaxPacketSize = cpu_to_le16(512),
 		},
 		.bulk_source = {
 			.bLength = sizeof(descriptors.hs_descs.bulk_source),
 			.bDescriptorType = USB_DT_ENDPOINT,
 			.bEndpointAddress = 2 | USB_DIR_OUT,
 			.bmAttributes = USB_ENDPOINT_XFER_BULK,
-			.wMaxPacketSize = htole16(512),
+			.wMaxPacketSize = cpu_to_le16(512),
 		},
 	},
 };
@@ -125,13 +143,13 @@ static const struct {
 	} __attribute__ ((__packed__)) lang0;
 } __attribute__ ((__packed__)) strings = {
 	.header = {
-		.magic = htole32(FUNCTIONFS_STRINGS_MAGIC),
-		.length = htole32(sizeof(strings)),
-		.str_count = htole32(1),
-		.lang_count = htole32(1),
+		.magic = cpu_to_le32(FUNCTIONFS_STRINGS_MAGIC),
+		.length = cpu_to_le32(sizeof(strings)),
+		.str_count = cpu_to_le32(1),
+		.lang_count = cpu_to_le32(1),
 	},
 	.lang0 = {
-		htole16(0x0409), /* en-us */
+		cpu_to_le16(0x0409), /* en-us */
 		STR_INTERFACE,
 	},
 };
-- 
2.37.3