The BAM Data Multiplexer provides access to the network data channels of modems integrated into many older Qualcomm SoCs, e.g. Qualcomm MSM8916 or MSM8974. This series adds a driver that allows using it. For more information about BAM-DMUX, see PATCH 4/4. Shortly said, BAM-DMUX is built using a simple protocol layer on top of a DMA engine (Qualcomm BAM DMA). For BAM-DMUX, the BAM DMA engine runs in a quite strange mode that I call "remote power collapse", where the modem/remote side is responsible for powering on the BAM when needed but we are responsible to initialize it. The BAM is power-collapsed when unneeded by coordinating power control via bidirectional interrupts from the BAM-DMUX driver. The series first adds one possible solution for handling this "remote power collapse" mode in the bam_dma driver, then it adds the BAM-DMUX driver to the WWAN subsystem. Note that the BAM-DMUX driver does not actually make use of the WWAN subsystem yet, since I'm not sure how to fit it in there yet (see PATCH 4/4). Please note that all of the changes in this patch series are based on a fairly complicated driver from Qualcomm [1]. I do not have access to any documentation about "BAM-DMUX". :( The driver has been used in postmarketOS [2] on various smartphones/tablets based on Qualcomm MSM8916 and MSM8974 for a year now with no reported problems. At runtime (but not compile-time), the following two patches are needed additionally for full functionality: - https://lore.kernel.org/linux-arm-msm/20210712135703.324748-1-stephan@xxxxxxxxxxx/ - https://lore.kernel.org/linux-arm-msm/20210712135703.324748-2-stephan@xxxxxxxxxxx/ [1]: https://source.codeaurora.org/quic/la/kernel/msm-3.10/tree/drivers/soc/qcom/bam_dmux.c?h=LA.BR.1.2.9.1-02310-8x16.0 [2]: https://postmarketos.org/ Stephan Gerhold (4): dt-bindings: dmaengine: bam_dma: Add remote power collapse mode dmaengine: qcom: bam_dma: Add remote power collapse mode dt-bindings: net: Add schema for Qualcomm BAM-DMUX net: wwan: Add Qualcomm BAM-DMUX WWAN network driver .../devicetree/bindings/dma/qcom_bam_dma.txt | 2 + .../bindings/net/qcom,bam-dmux.yaml | 87 ++ MAINTAINERS | 8 + drivers/dma/qcom/bam_dma.c | 88 +- drivers/net/wwan/Kconfig | 13 + drivers/net/wwan/Makefile | 1 + drivers/net/wwan/qcom_bam_dmux.c | 907 ++++++++++++++++++ 7 files changed, 1074 insertions(+), 32 deletions(-) create mode 100644 Documentation/devicetree/bindings/net/qcom,bam-dmux.yaml create mode 100644 drivers/net/wwan/qcom_bam_dmux.c -- 2.32.0
