This adds support for allocating DMA buffers on systems that support it,
i.e. Linux and Android.
On mainline Linux, starting version 5.6 (equivalent to Android 12),
there is a new kernel module framework available called [DMA-BUF
Heaps](https://github.com/torvalds/linux/blob/master/drivers/dma-buf/dma-heap.c).
The goal of this framework is to provide a standardised way for user
applications to allocate and share memory buffers between different
devices, subsystems, etc. The main feature of interest is that the
framework provides device-agnostic allocation; it abstracts away the
underlying hardware, and provides a single IOCTL,
`DMA_HEAP_IOCTL_ALLOC`. Mainline implementation provides two heaps that
act as character devices that can allocate DMA buffers; system, which
uses the buddy allocator, and cma, which uses the
[CMA](https://developer.toradex.com/software/linux-resources/linux-features/contiguous-memory-allocator-cma-linux/)
(Contiguous Memory Allocator). Both of these are [kernel configuration
options](https://github.com/torvalds/linux/blob/master/drivers/dma-buf/heaps/Kconfig)
that need to be enabled when building the Linux kernel. Generally, any
kernel module implementing this framework is made available under
/dev/dma_heaps/<heap_name>, e.g. /dev/dma_heaps/system.
The implementation currently only supports one type of DMA heaps;
`system`, the default device path for which is `/dev/dma_heap/system`.
The path can be overridden at runtime using an environment variable,
`OCL_CTS_DMA_HEAP_PATH_SYSTEM`, if needed. Extending this in the future
should be trivial (subject to platform support), by adding an entry to
the enum `dma_buf_heap_type`, and an appropriate default path and
overriding environment variable name.
The proposed implementation will conditionally compile if the conditions
are met (i.e. building for Linux or Android, using kernel headers >=
5.6.0), and will provide a compile-time warning otherwise, and return
`-1` as the DMA handle in runtime if not.
To demonstrate the functionality, a new test is added for the
`cl_khr_external_memory_dma_buf` extension. If the extension is
supported by the device, a DMA buffer will be allocated and used to
create a CL buffer, that is then used by a simple kernel.
This should provide a way forward for adding more tests that depend on
DMA buffers.
---------
Signed-off-by: Gorazd Sumkovski <gorazd.sumkovski@arm.com>
Signed-off-by: Ahmed Hesham <ahmed.hesham@arm.com>
Co-authored-by: Gorazd Sumkovski <gorazd.sumkovski@arm.com>
* Cleanup usage of static, extern and typedef
Remove static on functions defined headers, as it can result in
duplication in binaries.
Remove unnecessary extern keyword on a function declaration, as it is
the default behavior and can be puzzling when reading the code.
Remove the unused declaration of my_ilogb, which is never defined.
Remove unnecessary usage of typedef, as they are only increasing the
cognitive load of the code for no purpose.
Signed-off-by: Marco Antognini <marco.antognini@arm.com>
* Improve usage of inline and static in harness
Functions declared in header as static can trigger unused warnings when
(indirectly) included in translation units that do not use such
functions. Use inline instead, which also avoids duplicating symbols in
binaries.
Signed-off-by: Marco Antognini <marco.antognini@arm.com>
* Reformat common help text
Signed-off-by: Stuart Brady <stuart.brady@arm.com>
* Reformat test harness code
This goes part of the way to fixing issue #625.
Signed-off-by: Stuart Brady <stuart.brady@arm.com>
posix_memalign requires alignment to be a power of two and a multiple
of sizeof(void*). All powers of two greater than sizeof(void*) are
multiples of sizeof(void*) so we only need to make sure sizeof(void*)
is the minimum value passed to posix_memalign.
Fixes#644
Signed-off-by: Kevin Petit <kevin.petit@arm.com>
