Re: [PATCH v15 00/15] PCI: EP: Add RC-to-EP doorbell with platform MSI controller

[Frank Li <Frank.li@nxp.com>]

On Tue, Feb 11, 2025 at 02:21:53PM -0500, Frank Li wrote:

Thomas Gleixner and Marc Zyngier:

	Do you have any comments about irq/msi part?

Frank

> ┌────────────┐   ┌───────────────────────────────────┐   ┌────────────────┐
> │            │   │                                   │   │                │
> │            │   │ PCI Endpoint                      │   │ PCI Host       │
> │            │   │                                   │   │                │
> │            │◄──┤ 1.platform_msi_domain_alloc_irqs()│   │                │
> │            │   │                                   │   │                │
> │ MSI        ├──►│ 2.write_msi_msg()                 ├──►├─BAR<n>         │
> │ Controller │   │   update doorbell register address│   │                │
> │            │   │   for BAR                         │   │                │
> │            │   │                                   │   │ 3. Write BAR<n>│
> │            │◄──┼───────────────────────────────────┼───┤                │
> │            │   │                                   │   │                │
> │            ├──►│ 4.Irq Handle                      │   │                │
> │            │   │                                   │   │                │
> │            │   │                                   │   │                │
> └────────────┘   └───────────────────────────────────┘   └────────────────┘
>
> This patches based on old https://lore.kernel.org/imx/20221124055036.1630573-1-Frank.Li@nxp.com/
>
> Original patch only target to vntb driver. But actually it is common
> method.
>
> This patches add new API to pci-epf-core, so any EP driver can use it.
>
> Previous v2 discussion here.
> https://lore.kernel.org/imx/20230911220920.1817033-1-Frank.Li@nxp.com/
>
> Changes in v15:
> - rebase to v6.14-rc1
> - fix build issue find by kernel test robot
> - Link to v14: https://lore.kernel.org/r/20250207-ep-msi-v14-0-9671b136f2b8@nxp.com
>
> Changes in v14:
> Marc Zyngier raised concerns about adding DOMAIN_BUS_DEVICE_PCI_EP_MSI. As
> a result, the approach has been reverted to the v9 method. However, there
> are several improvements:
>
> MSI now supports msi-map in addition to msi-parent.
>   - The struct device: id is used as the endpoint function (EPF) device
> identity to map to the stream ID (sideband information).
>   - The EPC device tree source (DTS) utilizes msi-map to provide such
> information.
>   - The EPF device's of_node is set to the EPC controller’s node. This
> approach is commonly used for multi-function device (MFD) platform child
> devices, allowing them to inherit properties from the MFD device’s DTS,
> such as reset-cells and gpio-cells. This method is well-suited for the
> current case, as the EPF is inherently created/binded to the EPC and
> should inherit the EPC’s DTS node properties.
>
> Additionally:
>
> Since the basic IMX95 LUT support has already been merged into the
> mainline, a DTS and driver increment patch is added to complete the
> solution. The patch is rebased onto the latest linux-next tree and
> aligned with the new pcitest framework.
>
> - Link to v13: https://lore.kernel.org/r/20241218-ep-msi-v13-0-646e2192dc24@nxp.com
>
> Changes in v13:
> - Change to use DOMAIN_BUS_PCI_DEVICE_EP_MSI
> - Change request id as  func | vfunc << 3
> - Remove IRQ_DOMAIN_MSI_IMMUTABLE
>
> Thomas Gleixner:
>
> I hope capture all your points in review comments. If missed, let me know.
>
> - Link to v12: https://lore.kernel.org/r/20241211-ep-msi-v12-0-33d4532fa520@nxp.com
>
> Changes in v12:
> - Change to use IRQ_DOMAIN_MSI_IMMUTABLE and add help function
> irq_domain_msi_is_immuatble().
> - split PCI: endpoint: pci-ep-msi: Add MSI address/data pair mutable check to 3 patches
> - Link to v11: https://lore.kernel.org/r/20241209-ep-msi-v11-0-7434fa8397bd@nxp.com
>
> Changes in v11:
> - Change to use MSI_FLAG_MSG_IMMUTABLE
> - Link to v10: https://lore.kernel.org/r/20241204-ep-msi-v10-0-87c378dbcd6d@nxp.com
>
> Changes in v10:
>
> Thomas Gleixner:
> 	There are big change in pci-ep-msi.c. I am sure if go on the
> corrent path. The key improvement is remove only 1 function devices's
> limitation.
>
> 	I use new patch for imutable check, which relative additional
> feature compared to base enablement patch.
>
> - Remove patch Add msi_remove_device_irq_domain() in platform_device_msi_free_irqs_all()
> - Add new patch irqchip/gic-v3-its: Avoid overwriting msi_prepare callback if provided by msi_domain_info
> - Remove only support 1 endpoint function limiation.
> - Create one MSI domain for each endpoint function devices.
> - Use "msi-map" in pci ep controler node, instead of of msi-parent. first
> argument is
> 	(func_no << 8 | vfunc_no)
>
> - Link to v9: https://lore.kernel.org/r/20241203-ep-msi-v9-0-a60dbc3f15dd@nxp.com
>
> Changes in v9
> - Add patch platform-msi: Add msi_remove_device_irq_domain() in platform_device_msi_free_irqs_all()
> - Remove patch PCI: endpoint: Add pci_epc_get_fn() API for customizable filtering
> - Remove API pci_epf_align_inbound_addr_lo_hi
> - Move doorbell_alloc in to doorbell_enable function.
> - Link to v8: https://lore.kernel.org/r/20241116-ep-msi-v8-0-6f1f68ffd1bb@nxp.com
>
> Changes in v8:
> - update helper function name to pci_epf_align_inbound_addr()
> - Link to v7: https://lore.kernel.org/r/20241114-ep-msi-v7-0-d4ac7aafbd2c@nxp.com
>
> Changes in v7:
> - Add helper function pci_epf_align_addr();
> - Link to v6: https://lore.kernel.org/r/20241112-ep-msi-v6-0-45f9722e3c2a@nxp.com
>
> Changes in v6:
> - change doorbell_addr to doorbell_offset
> - use round_down()
> - add Niklas's test by tag
> - rebase to pci/endpoint
> - Link to v5: https://lore.kernel.org/r/20241108-ep-msi-v5-0-a14951c0d007@nxp.com
>
> Changes in v5:
> - Move request_irq to epf test function driver for more flexiable user case
> - Add fixed size bar handler
> - Some minor improvememtn to see each patches's changelog.
> - Link to v4: https://lore.kernel.org/r/20241031-ep-msi-v4-0-717da2d99b28@nxp.com
>
> Changes in v4:
> - Remove patch genirq/msi: Add cleanup guard define for msi_lock_descs()/msi_unlock_descs()
> - Use new method to avoid compatible problem.
>   Add new command DOORBELL_ENABLE and DOORBELL_DISABLE.
>   pcitest -B send DOORBELL_ENABLE first, EP test function driver try to
> remap one of BAR_N (except test register bar) to ITS MSI MMIO space. Old
> driver don't support new command, so failure return, not side effect.
>   After test, DOORBELL_DISABLE command send out to recover original map, so
> pcitest bar test can pass as normal.
> - Other detail change see each patches's change log
> - Link to v3: https://lore.kernel.org/r/20241015-ep-msi-v3-0-cedc89a16c1a@nxp.com
>
> Change from v2 to v3
> - Fixed manivannan's comments
> - Move common part to pci-ep-msi.c and pci-ep-msi.h
> - rebase to 6.12-rc1
> - use RevID to distingiush old version
>
> mkdir /sys/kernel/config/pci_ep/functions/pci_epf_test/func1
> echo 16 > /sys/kernel/config/pci_ep/functions/pci_epf_test/func1/msi_interrupts
> echo 0x080c > /sys/kernel/config/pci_ep/functions/pci_epf_test/func1/deviceid
> echo 0x1957 > /sys/kernel/config/pci_ep/functions/pci_epf_test/func1/vendorid
> echo 1 > /sys/kernel/config/pci_ep/functions/pci_epf_test/func1/revid
> ^^^^^^ to enable platform msi support.
> ln -s /sys/kernel/config/pci_ep/functions/pci_epf_test/func1 /sys/kernel/config/pci_ep/controllers/4c380000.pcie-ep
>
> - use new device ID, which identify support doorbell to avoid broken
> compatility.
>
>     Enable doorbell support only for PCI_DEVICE_ID_IMX8_DB, while other devices
>     keep the same behavior as before.
>
>            EP side             RC with old driver      RC with new driver
>     PCI_DEVICE_ID_IMX8_DB          no probe              doorbell enabled
>     Other device ID             doorbell disabled*       doorbell disabled*
>
>     * Behavior remains unchanged.
>
> Change from v1 to v2
> - Add missed patch for endpont/pci-epf-test.c
> - Move alloc and free to epc driver from epf.
> - Provide general help function for EPC driver to alloc platform msi irq.
> - Fixed manivannan's comments.
>
> Signed-off-by: Frank Li <Frank.Li@nxp.com>
> ---
> Frank Li (15):
>       platform-msi: Add msi_remove_device_irq_domain() in platform_device_msi_free_irqs_all()
>       irqdomain: Add IRQ_DOMAIN_FLAG_MSI_IMMUTABLE and irq_domain_is_msi_immutable()
>       irqchip/gic-v3-its: Set IRQ_DOMAIN_FLAG_MSI_IMMUTABLE for ITS
>       irqchip/gic-v3-its: Add support for device tree msi-map and msi-mask
>       PCI: endpoint: Set ID and of_node for function driver
>       PCI: endpoint: Add RC-to-EP doorbell support using platform MSI controller
>       PCI: endpoint: pci-ep-msi: Add MSI address/data pair mutable check
>       PCI: endpoint: Add pci_epf_align_inbound_addr() helper for address alignment
>       PCI: endpoint: pci-epf-test: Add doorbell test support
>       misc: pci_endpoint_test: Add doorbell test case
>       selftests: pci_endpoint: Add doorbell test case
>       pci: imx6: Add helper function imx_pcie_add_lut_by_rid()
>       pci: imx6: Add LUT setting for MSI/IOMMU in Endpoint mode
>       arm64: dts: imx95: Add msi-map for pci-ep device
>       arm64: dts: imx95-19x19-evk: Add PCIe1 endpoint function overlay file
>
>  arch/arm64/boot/dts/freescale/Makefile             |   3 +
>  .../dts/freescale/imx95-19x19-evk-pcie1-ep.dtso    |  21 ++++
>  arch/arm64/boot/dts/freescale/imx95.dtsi           |   1 +
>  drivers/base/platform-msi.c                        |   1 +
>  drivers/irqchip/irq-gic-v3-its-msi-parent.c        |   8 ++
>  drivers/irqchip/irq-gic-v3-its.c                   |   2 +-
>  drivers/misc/pci_endpoint_test.c                   |  81 +++++++++++++
>  drivers/pci/controller/dwc/pci-imx6.c              |  25 ++--
>  drivers/pci/endpoint/Makefile                      |   1 +
>  drivers/pci/endpoint/functions/pci-epf-test.c      | 132 +++++++++++++++++++++
>  drivers/pci/endpoint/pci-ep-msi.c                  |  90 ++++++++++++++
>  drivers/pci/endpoint/pci-epf-core.c                |  48 ++++++++
>  include/linux/irqdomain.h                          |   7 ++
>  include/linux/pci-ep-msi.h                         |  28 +++++
>  include/linux/pci-epf.h                            |  21 ++++
>  include/uapi/linux/pcitest.h                       |   1 +
>  .../selftests/pci_endpoint/pci_endpoint_test.c     |  25 ++++
>  17 files changed, 486 insertions(+), 9 deletions(-)
> ---
> base-commit: 2014c95afecee3e76ca4a56956a936e23283f05b
> change-id: 20241010-ep-msi-8b4cab33b1be
>
> Best regards,
> ---
> Frank Li <Frank.Li@nxp.com>
>