Add README.md file

Start by adding short build instructions. The documentation should be
expanded later.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

1 files changed, 51 insertions, 0 deletions

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+# uvcgadget - UVC gadget C library
+
+uvcgadget is a pure C library that implements handling of UVC gadget functions.
+
+## Utilities
+
+- uvc-gadget - Sample test application
+
+## Build instructions:
+
+To compile:
+
+```
+$ mkdir build
+$ cd build
+$ cmake ..
+$ make -j4
+```
+
+## Cross compiling instructions:
+
+Directions for cross compiling depend on the build environment.
+
+For buildroot-based builds, cmake can be pointed to the toolchain file provided
+by buildroot:
+
+```
+$ mkdir build
+$ cd build
+$ cmake -DCMAKE_TOOLCHAIN_FILE=<buildrootpath>/output/host/usr/share/buildroot/toolchainfile.cmake ..
+$ make -j4
+```
+
+If your build environment doesn't provide a CMake toolchain file, the following
+template can be used as a starting point.
+
+```
+set(CMAKE_SYSTEM_NAME Linux)
+
+set(BUILD_ENV_ROOT "/path/to/your/build/enviroment/root/")
+
+# Specify the cross compiler
+set(CMAKE_C_COMPILER   ${BUILD_ENV_ROOT}/host/usr/bin/arm-buildroot-linux-gnueabihf-gcc)
+
+# Where is the target environment
+set(CMAKE_FIND_ROOT_PATH ${BUILD_ENV_ROOT}/target ${BUILD_ENV_ROOT}/host)
+
+set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
+```