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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. It is built using a simple protocol layer on top of a DMA engine (Qualcomm BAM) and bidirectional interrupts to coordinate power control. The modem announces a fixed set of channels by sending an OPEN command. The driver exports each channel as separate network interface so that a connection can be established via QMI from userspace. The network interface can work either in Ethernet or Raw-IP mode (configurable via QMI). However, Ethernet mode seems to be broken with most firmwares (network packets are actually received as Raw-IP), therefore the driver only supports Raw-IP mode. Note that the control channel (QMI/AT) is entirely separate from BAM-DMUX and is already supported by the RPMSG_WWAN_CTRL driver. The driver uses runtime PM to coordinate power control with the modem. TX/RX buffers are put in a kind of "ring queue" and submitted via the bam_dma driver of the DMAEngine subsystem. The basic architecture looks roughly like this: +------------+ +-------+ [IPv4/6] | BAM-DMUX | | | [Data...] | | | | ---------->|wwan0 | [DMUX chan: x] | | [IPv4/6] | (chan: 0) | [IPv4/6] | | [Data...] | | [Data...] | | ---------->|wwan1 |--------------->| Modem | | (chan: 1) | BAM | | [IPv4/6] | ... | (DMA Engine) | | [Data...] | | | | ---------->|wwan7 | | | | (chan: 7) | | | +------------+ +-------+ Note that some newer firmware versions support QMAP ("rmnet" driver) as additional multiplexing layer on top of BAM-DMUX, but this is not currently supported by this driver. Signed-off-by: Stephan Gerhold <stephan@gerhold.net> Signed-off-by: David S. Miller <davem@davemloft.net>
16 lines
403 B
Makefile
16 lines
403 B
Makefile
# SPDX-License-Identifier: GPL-2.0
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#
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# Makefile for the Linux WWAN device drivers.
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#
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obj-$(CONFIG_WWAN) += wwan.o
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wwan-objs += wwan_core.o
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obj-$(CONFIG_WWAN_HWSIM) += wwan_hwsim.o
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obj-$(CONFIG_MHI_WWAN_CTRL) += mhi_wwan_ctrl.o
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obj-$(CONFIG_MHI_WWAN_MBIM) += mhi_wwan_mbim.o
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obj-$(CONFIG_QCOM_BAM_DMUX) += qcom_bam_dmux.o
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obj-$(CONFIG_RPMSG_WWAN_CTRL) += rpmsg_wwan_ctrl.o
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obj-$(CONFIG_IOSM) += iosm/
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