[PATCH v7 0/6] Add support for the LAN966x PCI device using a DT overlay

[Herve Codina]

Hi,

This series adds support for the LAN966x chip when used as a PCI
device.

For reference, the LAN996x chip is a System-on-chip that integrates an
Ethernet switch and a number of other traditional hardware blocks such
as a GPIO controller, I2C controllers, SPI controllers, etc. The
LAN996x can be used in two different modes:

- With Linux running on its Linux built-in ARM cores.
  This mode is already supported by the upstream Linux kernel, with the
  LAN996x described as a standard ARM Device Tree in
  arch/arm/boot/dts/microchip/lan966x.dtsi. Thanks to this support,
  all hardware blocks in the LAN996x already have drivers in the
  upstream Linux kernel.

- As a PCI device, thanks to its built-in PCI endpoint controller.
  In this case, the LAN996x ARM cores are not used, but all peripherals
  of the LAN996x can be accessed by the PCI host using memory-mapped
  I/O through the PCI BARs.

This series aims at supporting this second use-case. As all peripherals
of the LAN996x already have drivers in the Linux kernel, our goal is to
reuse them as-is to support this second use-case.

Therefore, this patch series introduces a PCI driver that binds on the
LAN996x PCI VID/PID, and when probed, instantiates all devices that are
accessible through the PCI BAR. As the list and characteristics of such
devices are non-discoverable, this PCI driver loads a Device Tree
overlay that allows to teach the kernel about which devices are
available, and allows to probe the relevant drivers in kernel, re-using
all existing drivers with no change.

This patch series for now adds a Device Tree overlay that describes an
initial subset of the devices available over PCI in the LAN996x, and
follow-up patch series will add support for more once this initial
support has landed.

In order to add this PCI driver, a number changes are needed:
 - Patches 1 and 2 introduce the LAN996x PCI driver itself, together
   with its DT overlay and the related MAINTAINER entry.

 - Patch 3 removes the syscon API usage from the reset driver used for
   the LAN966x.

 - Patches 4 to 7 allow the reset driver used for the LAN996x to be
   built as a module. Indeed, in the case where Linux runs on the ARM
   cores, it is common to have the reset driver built-in. However, when
   the LAN996x is used as a PCI device, it makes sense that all its
   drivers can be loaded as modules.

Compare to the previous iteration:
  https://lore.kernel.org/lkml/20240930121601.172216-1-herve.codina@bootlin.com/
this v7 series mainly:
  - Remove the patch modifying the reset controller DT binding
  - Re-order patches
  - Remove the syscon API usage from the LAN966x reset controller (the
    only syscon user).

Best regards,
Hervé

Changes v6 -> v7
  - Patch 1 (patch 3 in v6)
    Re-introduce the syscon node in the overlay

  - Patch 2 (patch 4 in v6)
    No changes

  - Patch 3 (patch 2 in v6)
    Rework code to map the syscon device locally without using the
    syscon API in the LAN966x case.
    Update commit log

  - Patches 4, 5 and 6 (patches 5, 6, and 7 in v6)
    No changes

  Patch removed in v7
    - Patch 1 in v6 (reset controller DT binding modification)
      Rejected

Changes v5 -> v6
  - Patch 1
    New patch in v6 relatead to removing syscon usage.

  - Patch 2
    New patch in v6 related to removing syscon usage.

  - Patch 3 (patch 1 in v5)
    Add 'Acked-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>'
    Remove syscon node from the overlay.

  - Patch 4, 5, 6 and 7 (patches 2, 4, 5 and 8 in v5)
    No changes

  Patches removed in v6
    - Patch 3 in v5
      Rejected

    - Patch 6 in v5
      No more applicable

    - Patch 7 in v5
      Already applied

Changes v4 -> v5
  - Patch 1
    Add missing include files and keep pci_ids.h.
    Remove IRQ_RETVAL() usage.
    Use __free().
    Remove the pdev->irq check.
    Avoid local variables in devm_pci_dev_remove_intr_ctrl() and
    lan966x_pci_load_overlay().
    Use dev_err_probe().
    Sort header includes in alphabetical order in dtbs file.

  - Patch 3
    Fix a typo in commit log.
    Simplify modification done in device_node_get_syscon().
    Use devm_add_action_or_reset().

  - Patches 4, 5, 6 and 8
    Add 'Reviewed-by: Steen Hegelund <Steen.Hegelund at microchip.com>'

Changes v3 -> v4
  - Patch 1 and 2 (v3 patch 6 and 7)
    Move the driver from drivers/mfd to drivers/misc.

  - Patch 4 and 5 (v3 patch 2)
    Rework reset driver dependencies and module building support.
    Split v3 patch into two distinct patches:
      - patch 4, as suggested by Geert, add a dependency on the
        LAN966x PCI device
      - patch 5, allows to build the reset controller driver as a module

  - Other patches
    Except reordering, no changes

Changes v2 -> v3
  - Patches 1 and 5
    No changes

  - Patch 6 (v2 patch 18)
    Add a blank line in the commit log to split paragraphs
    Remove unneeded header file inclusion
    Use IRQ_RETVAL()
    Remove blank line
    Use dev_of_node()
    Use pci_{set,get}_drvdata()
    Remove unneeded pci_clear_master() call
    Move { 0, } to { }
    Remove the unneeded pci_dev member from the lan966x_pci structure
    Use PCI_VENDOR_ID_EFAR instead of the hardcoded 0x1055 PCI Vendor ID
    Add a comment related to the of_node check.

  - Patch 7 (v2 patch 19)
    No changes

  Patches removed in v3
    - Patches 6 and 7
      Extracted and sent separately
      https://lore.kernel.org/lkml/20240620120126.412323-1-herve.codina@bootlin.com/

    - Patches 9
      Already applied

    - Patches 8, 10 to 12
      Extracted, reworked and sent separately
      https://lore.kernel.org/lkml/20240614173232.1184015-1-herve.codina@bootlin.com/

    - Patches 13 to 14
      Already applied

Changes v1 -> v2
  - Patch 1
    Fix a typo in syscon.h (s/intline/inline/)

  - Patches 2..5
    No changes

  - Patch 6
    Improve the reset property description

  - Patch 7
    Fix a wrong reverse x-mass tree declaration

  - Patch 8 removed (sent alone to net)
    https://lore.kernel.org/lkml/20240513111853.58668-1-herve.codina@bootlin.com/

  - Patch 8 (v1 patch 9)
    Add 'Reviewed-by: Rob Herring (Arm) <robh at kernel.org>'

  - Patch 9 (v1 patch 10)
    Rephrase and ident parameters descriptions

  - Patch 10 (v1 patch 11)
    No changes

  - Patch 11 (v1 patch 12)
    Fix a missing ret value assignment before a goto in .probe()
    Limit lines to 80 columns
    Use indices in register offset definitions

  - Patch 13 and 14 (new patches in v2)
    Add new test cases for existing of_changeset_add_prop_*()

  - Patch 15 (v1 patch 14)
    No changes

  - Patch 16 (new patches in v2)
    Add tests for of_changeset_add_prop_bool()

  - Patch 17 (v1 patch 15)
    Update commit subject
    Rewrap a paragraph in commit log

  - Patch 18 (v1 patch 16)
    Use PCI_IRQ_INTX instead of PCI_IRQ_LEGACY

  - Patch 19 (v1 patch 17)
    No changes

Clément Léger (2):
  reset: mchp: sparx5: Allow building as a module
  reset: mchp: sparx5: set the dev member of the reset controller

Herve Codina (4):
  misc: Add support for LAN966x PCI device
  MAINTAINERS: Add the Microchip LAN966x PCI driver entry
  reset: mchp: sparx5: Map cpu-syscon locally in case of LAN966x
  reset: mchp: sparx5: Add MCHP_LAN966X_PCI dependency

 MAINTAINERS                            |   6 +
 drivers/misc/Kconfig                   |  24 +++
 drivers/misc/Makefile                  |   3 +
 drivers/misc/lan966x_pci.c             | 215 +++++++++++++++++++++++++
 drivers/misc/lan966x_pci.dtso          | 167 +++++++++++++++++++
 drivers/pci/quirks.c                   |   1 +
 drivers/reset/Kconfig                  |   4 +-
 drivers/reset/reset-microchip-sparx5.c |  38 ++++-
 8 files changed, 455 insertions(+), 3 deletions(-)
 create mode 100644 drivers/misc/lan966x_pci.c
 create mode 100644 drivers/misc/lan966x_pci.dtso

-- 
2.46.1