This patch adds support for real-time DSP logging (timestamped events
and bespoke binary data) for firmware debug. The current solution
relies on DMA transfers to system memory that is then accessed by
userspace tools such as sof-logger. For Intel platforms, two types of
DMAs are currently used (GP-DMA for Baytrail/CherryTrail and HDaudio
DMA for SKL+)

Due to historical reasons, the driver code follows the DSP firmware
conventions and refers to 'traces', but it is currently unrelated to
the Linux trace subsystem. Future solutions will include support for
more advanced hardware (e.g. MIPI Sys-T), additional formats and the
ability to enable/disable specific traces dynamically.
Signed-off-by: Pan Xiuli <xiuli.pan@linux.intel.com>
Signed-off-by: Liam Girdwood <liam.r.girdwood@linux.intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Mark Brown <broonie@kernel.org>