can: esd: add support for esd GmbH PCIe/402 CAN interface

This patch picks up the work from last year. Any comments on needed or
recommended changes are appreciated.

The purpose of this patch is to introduce a new CAN driver to support
the esd GmbH 402 family of CAN interface boards. The hardware design
is based on a CAN controller implemented in a FPGA attached to a
PCIe link.

More information on these boards can be found following the links
included in the commit message.

This patch supports all boards but will operate the CAN-FD capable
boards only in Classic-CAN mode. The CAN-FD support will be added
when the initial patch has stabilized.

The patch is reuses the previous work of my former colleague:
Link: https://lore.kernel.org/linux-can/1426592308-23817-1-git-...


The patch is based on the linux-can-next main branch.

Changes in v8:
  - Rebased to 6.6-rc2 on linux-can-next branch main

Changes in v7:
  - Numerous changes. Find the quoted with inline comments about changes
    below after the changes list. Stuff that I don't understand and
    where I have questions is marked with ????.
    Unfortunately I will be AFK till 28th of November.

Changes in v6:
  - Fixed the statistic handling of RX overrun errors and increase 
    net_device_stats::rx_errors instead of net_device_stats::rx_dropped.
  - Added a patch to not increase rx statistics when generating a CAN
    rx error message frame as suggested on the linux-can list.
  - Added a patch to not not increase rx_bytes statistics for RTR frames
    as suggested on the linux-can list.

    The last two patches change the statistics handling from the previous
    style used in other drivers to the newly suggested one.

Changes in v5:
  - Added the initialization for netdev::dev_port as it is implemented
    for another CAN driver. See
    https://lore.kernel.org/linux-can/20211026180553.1953189-...

Changes in v4:
  - Fixed the build failure on ARCH=arm64 that was found by the Intel
    kernel test robot. See
    https://lore.kernel.org/linux-can/202109120608.7ZbQXkRh-l...

    Removed error monitoring code that used GCC's built-in compiler
    functions for atomic access (__sync_* functions). GCC versions
    after 9 (tested with "gcc-10 (Ubuntu 10.3.0-1ubuntu1~20.04)")
    don't implement the intrinsic atomic as in-line code but call
    "__aarch64_ldadd4_acq_rel" on arm64. This GCC support function
    is not exported by the kernel and therefore the module build
    post-processing fails.

    Removed that code because the error monitoring never showed a
    problem during the development this year.


Changes in v3:
  - Rework the bus-off restart logic in acc_set_mode() and
    handle_core_msg_errstatechange() to call netif_wake_queue() from the
    error active event.
  - Changed pci402_init_card() to allocate a variable sized array of
    struct acc_core using devm_kcalloc() instead of using a fixed size
    array in struct pci402_card.
  - Changed handle_core_msg_txabort() to release aborted TX frames in
    TX FIFO order.
  - Fixed the acc_close() function to abort all pending TX request in
    esdACC controller.
  - Fixed counting of transmit aborts in handle_core_msg_txabort().
    It is now done like in can_flush_echo_skb().
  - Fixed handle_core_msg_buserr() to create error frames including the
    CAN RX and TX error counters that were missing.
  - Fixed acc_set_bittiming() neither to touch LOM mode setting of
    esdACC controller nor to enter or leave RESET mode.
    The esdACC controller is going active on the CAN bus in acc_open()
    and is going inactive (RESET mode) again in acc_close().
  - Rely on the automatic release of memory fetched by devm_kzalloc().
    But still use devm_irq_free() explicitely to make sure that the
    interrupt handler is disconnected at that point.
    This avoids a possible crash in non-MSI mode due to the IRQ
    triggered by another device on the same PCI IRQ line.
  - Changed to use DMA map API instead of pci_*_consistent compatibility
    wrappers.
  - Fixed stale email references and updated copyright information.
  - Removed any traces of future CAN-FD support.


Changes in v2:
  - Avoid warning triggered by -Wshift-count-overflow on architectures
    with 32-bit dma_addr_t.
  - Fixed Makefile not to build the kernel module always. Doing this
    renamed esd402_pci.c to esd_402_pci-core.c as recommended by Marc.

previous versions:
v1 - https://lore.kernel.org/linux-can/20210728203647.15240-1-...
v2 - https://lore.kernel.org/linux-can/20210730173805.3926-1-S...
v3 - https://lore.kernel.org/linux-can/20210908164640.23243-1-...
v4 - https://lore.kernel.org/linux-can/20210916172152.5127-1-s...
v5 - https://lore.kernel.org/linux-can/20211109155326.2608822-...
v6 - https://lore.kernel.org/linux-can/20211201220328.3079270-...
v7 - https://lore.kernel.org/linux-can/20221106224156.3619334-...



Stefan Mätje (2):
  MAINTAINERS: add Stefan Mätje as maintainer for the esd electronics
    GmbH PCIe/402 CAN drivers
  can: esd: add support for esd GmbH PCIe/402 CAN interface family

 MAINTAINERS                            |   7 +
 drivers/net/can/Kconfig                |   1 +
 drivers/net/can/Makefile               |   1 +
 drivers/net/can/esd/Kconfig            |  12 +
 drivers/net/can/esd/Makefile           |   7 +
 drivers/net/can/esd/esd_402_pci-core.c | 510 ++++++++++++++++
 drivers/net/can/esd/esdacc.c           | 771 +++++++++++++++++++++++++
 drivers/net/can/esd/esdacc.h           | 393 +++++++++++++
 8 files changed, 1702 insertions(+)
 create mode 100644 drivers/net/can/esd/Kconfig
 create mode 100644 drivers/net/can/esd/Makefile
 create mode 100644 drivers/net/can/esd/esd_402_pci-core.c
 create mode 100644 drivers/net/can/esd/esdacc.c
 create mode 100644 drivers/net/can/esd/esdacc.h


base-commit: 93e7eca853ca0087b129433630ddd89288d2b8b4
-- 
2.25.1