Subject: Re: [PATCH net-next v3] net: Add Qcom WWAN control driver

From: Greg KH <[email-masked]>
Date: Tue, 9 Mar 2021 10:35:56 +0100

On Tue, Mar 09, 2021 at 09:42:16AM +0100, Loic Poulain wrote:
> The MHI WWWAN control driver allows MHI Qcom based modems to expose
> different modem control protocols/ports to userspace, so that userspace
> modem tools or daemon (e.g. ModemManager) can control WWAN config
> and state (APN config, SMS, provider selection...). A Qcom based
> modem can expose one or several of the following protocols:
> - AT: Well known AT commands interactive protocol (microcom, minicom...)
> - MBIM: Mobile Broadband Interface Model (libmbim, mbimcli)
> - QMI: Qcom MSM/Modem Interface (libqmi, qmicli)
> - QCDM: Qcom Modem diagnostic interface (libqcdm)
> - FIREHOSE: XML-based protocol for Modem firmware management
>         (qmi-firmware-update)
> 
> The different interfaces are exposed as character devices, in the same
> way as for USB modem variants (known as modem 'ports').
> 
> Note that this patch is mostly a rework of the earlier MHI UCI
> tentative that was a generic interface for accessing MHI bus from
> userspace. As suggested, this new version is WWAN specific and is
> dedicated to only expose channels used for controlling a modem, and
> for which related opensource user support exist. Other MHI channels
> not fitting the requirements will request either to be plugged to
> the right Linux subsystem (when available) or to be discussed as a
> new MHI driver (e.g AI accelerator, WiFi debug channels, etc...).
> 
> This change introduces a new drivers/net/wwan directory, aiming to
> be the common place for WWAN drivers.
> 
> Co-developed-by: Hemant Kumar <[email-masked]>
> Signed-off-by: Hemant Kumar <[email-masked]>
> Signed-off-by: Loic Poulain <[email-masked]>
> ---
>  v2: update copyright (2021)
>  v3: Move driver to dedicated drivers/net/wwan directory
> 
>  drivers/net/Kconfig              |   2 +
>  drivers/net/Makefile             |   1 +
>  drivers/net/wwan/Kconfig         |  26 ++
>  drivers/net/wwan/Makefile        |   6 +
>  drivers/net/wwan/mhi_wwan_ctrl.c | 559 +++++++++++++++++++++++++++++++++++++++
>  5 files changed, 594 insertions(+)
>  create mode 100644 drivers/net/wwan/Kconfig
>  create mode 100644 drivers/net/wwan/Makefile
>  create mode 100644 drivers/net/wwan/mhi_wwan_ctrl.c
> 
> diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
> index 1ebb4b9..28b18f2 100644
> --- a/drivers/net/Kconfig
> +++ b/drivers/net/Kconfig
> @@ -501,6 +501,8 @@ source "drivers/net/wan/Kconfig"
>  
>  source "drivers/net/ieee802154/Kconfig"
>  
> +source "drivers/net/wwan/Kconfig"
> +
>  config XEN_NETDEV_FRONTEND
>  	tristate "Xen network device frontend driver"
>  	depends on XEN
> diff --git a/drivers/net/Makefile b/drivers/net/Makefile
> index f4990ff..5da6424 100644
> --- a/drivers/net/Makefile
> +++ b/drivers/net/Makefile
> @@ -68,6 +68,7 @@ obj-$(CONFIG_SUNGEM_PHY) += sungem_phy.o
>  obj-$(CONFIG_WAN) += wan/
>  obj-$(CONFIG_WLAN) += wireless/
>  obj-$(CONFIG_IEEE802154) += ieee802154/
> +obj-$(CONFIG_WWAN) += wwan/
>  
>  obj-$(CONFIG_VMXNET3) += vmxnet3/
>  obj-$(CONFIG_XEN_NETDEV_FRONTEND) += xen-netfront.o
> diff --git a/drivers/net/wwan/Kconfig b/drivers/net/wwan/Kconfig
> new file mode 100644
> index 0000000..643aa10
> --- /dev/null
> +++ b/drivers/net/wwan/Kconfig
> @@ -0,0 +1,26 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +#
> +# Wireless WAN device configuration
> +#
> +
> +menuconfig WWAN
> +       bool "Wireless WAN"
> +       help
> +         This section contains Wireless WAN driver configurations.
> +
> +if WWAN
> +
> +config MHI_WWAN_CTRL
> +	tristate "MHI WWAN control driver for QCOM based PCIe modems"
> +	depends on MHI_BUS
> +	help
> +	  MHI WWAN CTRL allow QCOM based PCIe modems to expose different modem
> +	  control protocols/ports to userspace, including AT, MBIM, QMI, DIAG
> +	  and FIREHOSE. These protocols can be accessed directly from userspace
> +	  (e.g. AT commands) or via libraries/tools (e.g. libmbim, libqmi,
> +	  libqcdm...).
> +
> +	  To compile this driver as a module, choose M here: the module will be
> +	  called mhi_wwan_ctrl.
> +
> +endif # WWAN
> diff --git a/drivers/net/wwan/Makefile b/drivers/net/wwan/Makefile
> new file mode 100644
> index 0000000..994a80b
> --- /dev/null
> +++ b/drivers/net/wwan/Makefile
> @@ -0,0 +1,6 @@
> +# SPDX-License-Identifier: GPL-2.0
> +#
> +# Makefile for the Linux WWAN device drivers.
> +#
> +
> +obj-$(CONFIG_MHI_WWAN_CTRL) += mhi_wwan_ctrl.o
> diff --git a/drivers/net/wwan/mhi_wwan_ctrl.c b/drivers/net/wwan/mhi_wwan_ctrl.c
> new file mode 100644
> index 0000000..3904cd0
> --- /dev/null
> +++ b/drivers/net/wwan/mhi_wwan_ctrl.c
> @@ -0,0 +1,559 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/* Copyright (c) 2018-2021, The Linux Foundation. All rights reserved.*/
> +
> +#include <linux/kernel.h>
> +#include <linux/mhi.h>
> +#include <linux/mod_devicetable.h>
> +#include <linux/module.h>
> +#include <linux/poll.h>
> +
> +#define MHI_WWAN_CTRL_DRIVER_NAME "mhi_wwan_ctrl"

So a driver name is the same as the class that is being created?

That feels wrong, shouldn't the "class" be wwan?

> +#define MHI_WWAN_CTRL_MAX_MINORS 128

Why so many?

thanks,

greg k-h