| Message ID | 20240430083730.134918-1-herve.codina@bootlin.com |
|---|---|
| Headers | show |
| Series | Add support for the LAN966x PCI device using a DT overlay | expand |
On Tue, Apr 30, 2024 at 10:37:09AM +0200, Herve Codina wrote: > Hi, > > This series adds support for the LAN966x chip when used as a PCI > device. > 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. What host systems have you tested with? Are they all native DT, or have you tested on an ACPI system? I'm just wondering how well DT overlay works if i were to plug a LAN966x device into something like an x86 ComExpress board? Andrew
Hi Andrew, On Tue, 30 Apr 2024 15:40:16 +0200 Andrew Lunn <andrew@lunn.ch> wrote: > On Tue, Apr 30, 2024 at 10:37:09AM +0200, Herve Codina wrote: > > Hi, > > > > This series adds support for the LAN966x chip when used as a PCI > > device. > > > 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. > > What host systems have you tested with? Are they all native DT, or > have you tested on an ACPI system? I'm just wondering how well DT > overlay works if i were to plug a LAN966x device into something like > an x86 ComExpress board? I tested on a native DT system (marvell board). Also I tested on a x86 system (basically a simple PC). Not all components are available upstream to have it working on a x86 (ACPI) system. The missing component is not related to the LAN966x PCI driver itself but in the way DT node are created up to the PCI device. A DT node at PCI device is needed to have a DT node parent (target) for the overlay. The DT node chain is also important because BARs address translations are done using the 'ranges' property available in each node in the chain. On a full DT system, the DT looks like (simplified in naming and without the node properties): / soc { ... pci_root_bridge { <-- Present in base dts pci_to_pci_bridge { <-- Created at runtime based on PCI enumeration pci_device { <-- Created at runtime based on PCI enumeration } } pci_device { <-- Created at runtime based on PCI enumeration }; }; }; On x86: - A DT root empty node is created. This is already upstream from a first proposal [1] and then second one [2]. - PCI-to-PCI bridge and device DT nodes are created at runtime. This is the same on DT base systems and this feature is available upstream too (last proposal at [3]). The DT node missing in the chain is the node for the PCI root bridge. On ACPI, no "base" dts describes this node. The PCI root bridge is described by ACPI. I have some draft code that create this DT node when a PCI host bridge is register if a DT node is not already present and so fill the hole in the DT node chain. With that the DT in an ACPI system looks like this: / pci_root_bridge { <-- Created at runtime when a PCI host bridge is registered pci_to_pci_bridge { <-- Created at runtime based on PCI enumeration pci_device { <-- Created at runtime based on PCI enumeration } } pci_device { <-- Created at runtime based on PCI enumeration }; }; With this node added, the driver works the same way in both DT and ACPI systems without any modification. I plan to send the code creating the PCI host bridge node when this current series is landed in order to add support for DT overlay over PCI on x86 systems. Also an other series (under review [4]) is needed to avoid struct device duplication related to the DT nodes creation. [1] https://lore.kernel.org/lkml/20230317053415.2254616-1-frowand.list@gmail.com/#r [2] https://lore.kernel.org/lkml/20240217010557.2381548-1-sboyd@kernel.org/ [3] https://lore.kernel.org/lkml/1692120000-46900-1-git-send-email-lizhi.hou@amd.com/ [4] https://lore.kernel.org/lkml/20240423145703.604489-1-herve.codina@bootlin.com/ Best regards, Hervé
> Also I tested on a x86 system (basically a simple PC). > Not all components are available upstream to have it working on a x86 (ACPI) > system. The missing component is not related to the LAN966x PCI driver itself > but in the way DT node are created up to the PCI device. Good to hear it nearly "just works". There does not seem to be any interest in describing complex network devices like this using ACPI, which is many years behind what we have in DT in terms of building blocks for networking devices. Like many PCIe devices, the LAN966x is pretty much self contained, so fits DT overlays nicely. There is also a slowly growing trend to have PCIe network devices which Linux controls, rather than offloading to firmware. The wangxun drivers are another example. So it is great to see the remaining pieces being put in place to support this. Thanks Andrew
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 re-use 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 of preparation changes are needed: - Patches 1 to 5 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. - Patches 6 and 7 improve the MDIO controller driver to properly handle its reset signal. - Patch 8 fixes an issue in the LAN996x switch driver. - Patches 9 to 13 introduce the internal interrupt controller used in the LAN996x. It is one of the few peripherals in the LAN996x that are only relevant when the LAN996x is used as a PCI device, which is why this interrupt controller did not have a driver so far. - Patches 14 and 15 make some small additions to the OF core and PCI/OF core to consider the PCI device as an interrupt controller. This topic was previously mentioned in [1] to avoid the need of phandle interrupt parents which are not available at some points. - Patches 16 and 17 introduce the LAN996x PCI driver itself, together with its DT bindings. We believe all items from the above list can be merged separately, with no build dependencies. We expect: - Patches 1 to 5 to be taken by reset maintainers - Patches 6, 7 and 8 to be taken by network driver maintainers - Patches 9 to 13 to be taken by irqchip maintainers - Patch 14/15 to be taken by DT/PCI maintainers - Patch 16/17 by the MFD maintainers Additionally, we also believe all preparation items in this patch series can be taken even before there's a final agreement on the last part of the series (the MFD driver itself). [1] https://lore.kernel.org/all/CAL_Jsq+je7+9ATR=B6jXHjEJHjn24vQFs4Tvi9=vhDeK9n42Aw@mail.gmail.com/ Best regards, Hervé Clément Léger (5): mfd: syscon: Add reference counting and device managed support reset: mchp: sparx5: Remove dependencies and allow building as a module reset: mchp: sparx5: Release syscon when not use anymore reset: core: add get_device()/put_device on rcdev reset: mchp: sparx5: set the dev member of the reset controller Herve Codina (12): dt-bindings: net: mscc-miim: Add resets property net: mdio: mscc-miim: Handle the switch reset net: lan966x: remove debugfs directory in probe() error path dt-bindings: interrupt-controller: Add support for Microchip LAN966x OIC irqdomain: Add missing parameter descriptions in docs irqdomain: Introduce irq_domain_alloc() and irq_domain_publish() irqchip: Add support for LAN966x OIC MAINTAINERS: Add the Microchip LAN966x OIC driver entry of: dynamic: Introduce of_changeset_add_prop_bool() pci: of_property: Add the interrupt-controller property in PCI device nodes mfd: Add support for LAN966x PCI device MAINTAINERS: Add the Microchip LAN966x PCI driver entry .../microchip,lan966x-oic.yaml | 55 ++++ .../devicetree/bindings/net/mscc,miim.yaml | 8 + MAINTAINERS | 12 + drivers/irqchip/Kconfig | 12 + drivers/irqchip/Makefile | 1 + drivers/irqchip/irq-lan966x-oic.c | 301 ++++++++++++++++++ drivers/mfd/Kconfig | 24 ++ drivers/mfd/Makefile | 4 + drivers/mfd/lan966x_pci.c | 229 +++++++++++++ drivers/mfd/lan966x_pci.dtso | 167 ++++++++++ drivers/mfd/syscon.c | 145 ++++++++- .../ethernet/microchip/lan966x/lan966x_main.c | 6 +- drivers/net/mdio/mdio-mscc-miim.c | 8 + drivers/of/dynamic.c | 25 ++ drivers/pci/of_property.c | 24 ++ drivers/pci/quirks.c | 1 + drivers/reset/Kconfig | 3 +- drivers/reset/core.c | 2 + drivers/reset/reset-microchip-sparx5.c | 11 +- include/linux/irqdomain.h | 16 + include/linux/mfd/syscon.h | 18 ++ include/linux/of.h | 3 + kernel/irq/irqdomain.c | 118 +++++-- 23 files changed, 1149 insertions(+), 44 deletions(-) create mode 100644 Documentation/devicetree/bindings/interrupt-controller/microchip,lan966x-oic.yaml create mode 100644 drivers/irqchip/irq-lan966x-oic.c create mode 100644 drivers/mfd/lan966x_pci.c create mode 100644 drivers/mfd/lan966x_pci.dtso