[PATCH v14 00/15] PCI: EP: Add RC-to-EP doorbell with platform MSI controller

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

┌────────────┐   ┌───────────────────────────────────┐   ┌────────────────┐
│            │   │                                   │   │                │
│            │   │ 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 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                      |   2 +-
 drivers/pci/endpoint/functions/pci-epf-test.c      | 132 +++++++++++++++++++++
 drivers/pci/endpoint/pci-ep-msi.c                  |  89 ++++++++++++++
 drivers/pci/endpoint/pci-epf-core.c                |  48 ++++++++
 include/linux/irqdomain.h                          |   7 ++
 include/linux/pci-ep-msi.h                         |  26 ++++
 include/linux/pci-epf.h                            |  21 ++++
 include/uapi/linux/pcitest.h                       |   1 +
 .../selftests/pci_endpoint/pci_endpoint_test.c     |  25 ++++
 17 files changed, 483 insertions(+), 10 deletions(-)
---
base-commit: 00f3246adeeacbda0bd0b303604e46eb59c32e6e
change-id: 20241010-ep-msi-8b4cab33b1be

Best regards,
---
Frank Li <Frank.Li@nxp.com>