[PATCH v10 0/6] Add support for the LAN966x PCI device using a DT overlay

From: Herve Codina
Date: Mon Oct 14 2024 - 08:47:04 EST

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/20241010063611.788527-1-herve.codina@xxxxxxxxxxx/
this v10 series mainly:
- Update Kconfig help section
- Add "Acked-by" tag

Best regards,
Hervé

Changes v9 -> v10
- Patch 1
Use 'device tree overlay' instead of just 'overlay' in Kconfig help
and re-format the section.
Add 'Acked-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> # quirks.c'

Changes v9 -> v8
v8 was incorrect (modifications not present).
v9 fixed that and contains modification that should be present in v8

Changes v7 -> v8
- Patch 1
Add missing spaces around '=' in dtso

- Patches 2, 4, 5 and 6
Add 'Reviewed-by: Philipp Zabel <p.zabel@xxxxxxxxxxxxxx>'

- Patch 3
Add 'Reviewed-by: Steen Hegelund <Steen.Hegelund@xxxxxxxxxxxxx>'
Add 'Reviewed-by: Philipp Zabel <p.zabel@xxxxxxxxxxxxxx>'

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@xxxxxxxxxxxxxxxxxxx>'
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@xxxxxxxxxxxxx>'

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@xxxxxxxxxxx/

- Patches 9
Already applied

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

- 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@xxxxxxxxxxx/

- Patch 8 (v1 patch 9)
Add 'Reviewed-by: Rob Herring (Arm) <robh@xxxxxxxxxx>'

- 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

--
2.46.2