ASoC: codecs: add SoundWire mockup device support

To test the host controller and bus management code, it is currently
required to have a physical SoundWire peripheral attached to the
bus. To help with pre-silicon or early hardware enablement, it would
be very useful to have a SoundWire 'mockup' device that is exposed in
platform firmware but does not drive any signal on the bus.

This is different to the existing ASoC 'dummy' codec uses for I2S/TDM,
the SoundWire spec makes it clear that a device that is not attached
to the bus is not permitted to interact with the bus, be it for
command/control or data.

This patch exposes a 'mockup' device, with a minimalist driver, with 4
partID values reserved by Intel for such test configurations. The
mockup device exposes one full-duplex DAI based on 2 ports (DP1 for
playback and DP8 for capture). The capture data port is just virtual,
such a mockup device is prevented by the SoundWire specification from
presenting any data generated by a Source port without being Attached.

All the callbacks exposed by the SoundWire Slave interface are
populated, even if they just return immediately. This is intentional
to describe what a minimal codec driver should do and implement and
help new codec vendors provide support for their devices.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Rander Wang <rander.wang@intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Link: https://lore.kernel.org/r/20210714032209.11284-2-yung-chuan.liao@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/sound/soc/codecs/Makefile b/sound/soc/codecs/Makefile
index de8b83dd2c76..d656b1405473 100644
--- a/sound/soc/codecs/Makefile
+++ b/sound/soc/codecs/Makefile
@@ -203,6 +203,7 @@ snd-soc-rt711-objs := rt711.o rt711-sdw.o
 snd-soc-rt711-sdca-objs := rt711-sdca.o rt711-sdca-sdw.o
 snd-soc-rt715-objs := rt715.o rt715-sdw.o
 snd-soc-rt715-sdca-objs := rt715-sdca.o rt715-sdca-sdw.o
+snd-soc-sdw-mockup-objs := sdw-mockup.o
 snd-soc-sgtl5000-objs := sgtl5000.o
 snd-soc-alc5623-objs := alc5623.o
 snd-soc-alc5632-objs := alc5632.o
@@ -530,6 +531,7 @@ obj-$(CONFIG_SND_SOC_RT711)     += snd-soc-rt711.o
 obj-$(CONFIG_SND_SOC_RT711_SDCA_SDW)     += snd-soc-rt711-sdca.o
 obj-$(CONFIG_SND_SOC_RT715)     += snd-soc-rt715.o
 obj-$(CONFIG_SND_SOC_RT715_SDCA_SDW)     += snd-soc-rt715-sdca.o
+obj-$(CONFIG_SND_SOC_SDW_MOCKUP)     += snd-soc-sdw-mockup.o
 obj-$(CONFIG_SND_SOC_SGTL5000)  += snd-soc-sgtl5000.o
 obj-$(CONFIG_SND_SOC_SIGMADSP)	+= snd-soc-sigmadsp.o
 obj-$(CONFIG_SND_SOC_SIGMADSP_I2C)	+= snd-soc-sigmadsp-i2c.o