[PATCH v9 0/6] Add support for the LAN966x PCI device using a DT overlay

Herve Codina
2024-10-10T06:36:16Z

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.

The v8 series sent didn't contains the expected modification and have to
be simply ignore.
This v9 series fixes that and contains modification expected in v8

Compare to the previous iteration:
https://lore.kernel.org/lkml/20241003081647.642468-1-herve.codina@bootlin.com/
this v9 series mainly:
- Add missing spaces
- Add "Reviewed-by" tags

Best regards,
Hervé

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@pengutronix.de>'

- Patch 3
Add 'Reviewed-by: Steen Hegelund <Steen.Hegelund@microchip.com>'
Add 'Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>'

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@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@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@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

--
2.46.2