The BAM Data Multiplexer provides access to the network data channels
of modems integrated into many older Qualcomm SoCs, including MSM8916.

Add the nodes for the BAM DMA engine and BAM-DMUX to enable using WWAN
on smartphones/tablets based on MSM8916. This should work out of the box
with open-source WWAN userspace such as ModemManager.

The nodes are disabled by default to avoid loading unnecessary drivers
on devices that cannot use BAM-DMUX (e.g. DragonBoard 410c). However,
strictly speaking the nodes could be enabled by default since both the
bam_dma and bam_dmux driver will simply do nothing if the modem does
not announce any BAM-DMUX channels.
Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220228225400.146555-3-stephan@gerhold.net