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tools: usb: ffs-test: Fix build on big endian systems 

The tools/usb/ffs-test.c file defines cpu_to_le16/32 by using the C
library htole16/32 function calls. However, cpu_to_le16/32 are used when
initializing structures, i.e in a context where a function call is not
allowed.

It works fine on little endian systems because htole16/32 are defined by
the C library as no-ops. But on big-endian systems, they are actually
doing something, which might involve calling a function, causing build
failures, such as:

   ffs-test.c:48:25: error: initializer element is not constant
    #define cpu_to_le32(x)  htole32(x)
                            ^~~~~~~
   ffs-test.c:128:12: note: in expansion of macro ‘cpu_to_le32’
      .magic = cpu_to_le32(FUNCTIONFS_DESCRIPTORS_MAGIC_V2),
               ^~~~~~~~~~~

To solve this, we code cpu_to_le16/32 in a way that allows them to be
used when initializing structures. This fix was imported from
meta-openembedded/android-tools/fix-big-endian-build.patch written by
Thomas Petazzoni <thomas.petazzoni@free-electrons.com>.

CC: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Senna Tschudin <peter.senna@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Peter Senna Tschudin 2018-07-10 16:01:45 +02:00 committed by Greg Kroah-Hartman
parent db9fc500e8
commit 8975a68d8c
1 changed files with 16 additions and 3 deletions
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19
tools/usb/ffs-test.c
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@ -44,12 +44,25 @@
/******************** Little Endian Handling ********************************/
#define cpu_to_le16(x) htole16(x)
#define cpu_to_le32(x) htole32(x)
/*
* 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
#define le32_to_cpu(x) le32toh(x)
#define le16_to_cpu(x) le16toh(x)
/******************** Messages and Errors ***********************************/
static const char argv0[] = "ffs-test";