[PATCH v4 0/5] PCI: EP: Add RC-to-EP doorbell with platform MSI controller

[Frank Li]

┌────────────┐   ┌───────────────────────────────────┐   ┌────────────────┐
│            │   │                                   │   │                │
│            │   │ 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@xxxxxxx/

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@xxxxxxx/

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@xxxxxxx

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.

To: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
To: Krzysztof Wilczyński <kw@xxxxxxxxx>
To: Kishon Vijay Abraham I <kishon@xxxxxxxxxx>
To: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
To: Arnd Bergmann <arnd@xxxxxxxx>
To: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: linux-pci@xxxxxxxxxxxxxxx
Cc: imx@xxxxxxxxxxxxxxx
Cc: Niklas Cassel <cassel@xxxxxxxxxx>
Cc: cassel@xxxxxxxxxx
Cc: dlemoal@xxxxxxxxxx
Cc: maz@xxxxxxxxxx
Cc: tglx@xxxxxxxxxxxxx
Cc: jdmason@xxxxxxxx

Signed-off-by: Frank Li <Frank.Li@xxxxxxx>
---
Frank Li (5):
      PCI: endpoint: Add pci_epc_get_fn() API for customizable filtering
      PCI: endpoint: Add RC-to-EP doorbell support using platform MSI controller
      PCI: endpoint: pci-epf-test: Add doorbell test support
      misc: pci_endpoint_test: Add doorbell test case
      tools: PCI: Add 'B' option for test doorbell

 drivers/misc/pci_endpoint_test.c              |  63 +++++++++++++
 drivers/pci/endpoint/Makefile                 |   2 +-
 drivers/pci/endpoint/functions/pci-epf-test.c | 104 +++++++++++++++++++++
 drivers/pci/endpoint/pci-ep-msi.c             | 128 ++++++++++++++++++++++++++
 drivers/pci/endpoint/pci-epc-core.c           |  23 ++++-
 include/linux/pci-ep-msi.h                    |  15 +++
 include/linux/pci-epc.h                       |   2 +
 include/linux/pci-epf.h                       |  19 ++++
 include/uapi/linux/pcitest.h                  |   1 +
 tools/pci/pcitest.c                           |  16 +++-
 10 files changed, 369 insertions(+), 4 deletions(-)
---
base-commit: f231847d7f5a171be4566099f654521606b3ec37
change-id: 20241010-ep-msi-8b4cab33b1be

Best regards,
---
Frank Li <Frank.Li@xxxxxxx>