net: wwan: iosm: Convert single instance struct member to flexible array

struct mux_adth actually ends with multiple struct mux_adth_dg members.
This is seen both in the comments about the member:

/**
* struct mux_adth - Structure of the Aggregated Datagram Table Header.
...
* @dg: datagramm table with variable length
*/

and in the preparation for populating it:

adth_dg_size = offsetof(struct mux_adth, dg) +
ul_adb->dg_count[i] * sizeof(*dg);
...
adth_dg_size -= offsetof(struct mux_adth, dg);
memcpy(&adth->dg, ul_adb->dg[i], adth_dg_size);

This was reported as a run-time false positive warning:

memcpy: detected field-spanning write (size 16) of single field "&adth->dg" at drivers/net/wwan/iosm/iosm_ipc_mux_codec.c:852 (size 8)

Adjust the struct mux_adth definition and associated sizeof() math; no binary
output differences are observed in the resulting object file.

Reported-by: Florian Klink <flokli@flokli.de>
Closes: https://lore.kernel.org/lkml/dbfa25f5-64c8-5574-4f5d-0151ba95d232@gmail.com/
Fixes: 1f52d7b62285 ("net: wwan: iosm: Enable M.2 7360 WWAN card support")
Cc: M Chetan Kumar <m.chetan.kumar@intel.com>
Cc: Bagas Sanjaya <bagasdotme@gmail.com>
Cc: Intel Corporation <linuxwwan@intel.com>
Cc: Loic Poulain <loic.poulain@linaro.org>
Cc: Sergey Ryazanov <ryazanov.s.a@gmail.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Cc: netdev@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Link: https://lore.kernel.org/r/20230620194234.never.023-kees@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

net: wwan: iosm: fix incorrect skb length

skb passed to network layer contains incorrect length.

In mux aggregation protocol, the datagram block received
from device contains block signature, packet & datagram
header. The right skb len to be calculated by subracting
datagram pad len from datagram length.

Whereas in mux lite protocol, the skb contains single
datagram so skb len is calculated by subtracting the
packet offset from datagram header.

Fixes: 1f52d7b62285 ("net: wwan: iosm: Enable M.2 7360 WWAN card support")
Signed-off-by: M Chetan Kumar <m.chetan.kumar@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: wwan: iosm: fix crash in peek throughput test

Peek throughput UL test is resulting in crash. If the UL
transfer block free list is exhaust, the peeked skb is freed.
In the next transfer freed skb is referred from UL list which
results in crash.

Don't free the skb if UL transfer blocks are unavailable. The
pending skb will be picked for transfer on UL transfer block
available.

Fixes: 1f52d7b62285 ("net: wwan: iosm: Enable M.2 7360 WWAN card support")
Signed-off-by: M Chetan Kumar <m.chetan.kumar@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: wwan: iosm: fix kernel test robot reported error

sparse warnings - iosm_ipc_mux_codec.c:1474 using plain
integer as NULL pointer.

Use skb_trim() to reset skb tail & len.

Fixes: 9413491e20e1 ("net: iosm: encode or decode datagram")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: M Chetan Kumar <m.chetan.kumar@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: wwan: iosm: Enable M.2 7360 WWAN card support

This patch enables Intel M.2 7360 WWAN card support on
IOSM Driver.

Control path implementation is a reuse whereas data path
implementation it uses a different protocol called as MUX
Aggregation. The major portion of this patch covers the MUX
Aggregation protocol implementation used for IP traffic
communication.

For M.2 7360 WWAN card, driver exposes 2 wwan AT ports for
control communication. The user space application or the
modem manager to use wwan AT port for data path establishment.

During probe, driver reads the mux protocol device capability
register to know the mux protocol version supported by device.
Base on which the right mux protocol is initialized for data
path communication.

An overview of an Aggregation Protocol
1> An IP packet is encapsulated with 16 octet padding header
to form a Datagram & the start offset of the Datagram is
indexed into Datagram Header (DH).
2> Multiple such Datagrams are composed & the start offset of
each DH is indexed into Datagram Table Header (DTH).
3> The Datagram Table (DT) is IP session specific & table_length
item in DTH holds the number of composed datagram pertaining
to that particular IP session.
4> And finally the offset of first DTH is indexed into DBH (Datagram
Block Header).

So in TX/RX flow Datagram Block (Datagram Block Header + Payload)is
exchanged between driver & device.

Signed-off-by: M Chetan Kumar <m.chetan.kumar@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: wwan: iosm: release data channel in case no active IP session

If there is no active IP session (interface up & running) then
release the data channel.

Use nr_sessions variable to track current active IP sessions.
If the count drops to 0, then send pipe close ctrl message to
release the data channel.

Signed-off-by: M Chetan Kumar <m.chetan.kumar@linux.intel.com>
Reviewed-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net: wwan: iosm: endianness type correction

Endianness type correction for nr_of_bytes. This field is exchanged
as part of host-device protocol communication.

Signed-off-by: M Chetan Kumar <m.chetan.kumar@linux.intel.com>
Reviewed-by: Loic Poulain <loic.poulain@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: wwan: iosm: correct link-id handling

Link ID to be kept intact with MBIM session ID
Ex: ID 0 should be associated to MBIM session ID 0.

Reported-by: Loic Poulain <loic.poulain@linaro.org>
Signed-off-by: M Chetan Kumar <m.chetan.kumar@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: iosm: remove an unnecessary NULL check

The address of &ipc_mux->ul_adb can't be NULL because it points to the
middle of a non-NULL struct.

Fixes: 9413491e20e1 ("net: iosm: encode or decode datagram")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: M Chetan Kumar <m.chetan.kumar@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: iosm: encode or decode datagram

1) Encode UL packet into datagram.
2) Decode DL datagram and route it to network layer.
3) Supports credit based flow control.

Signed-off-by: M Chetan Kumar <m.chetan.kumar@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>