[PATCH v8 0/3] PCI: imx6: Add external reference clock mode support

[Richard Zhu]

i.MX95 PCIes have two reference clock inputs: one from internal PLL, the
other from off chip crystal oscillator. The "extref" clock refers to a
reference clock from an external crystal oscillator.

Add external reference clock input mode support for i.MX95 PCIes.

Main change in v8:
- Rebase to v6.18-rc1.
- No need to initialize bool parameter to the deault value "false" refer
  to Mani' comments in v7

Main change in v7:
- Refine the subjects and commit message refer to Bjorn's comments.
https://lore.kernel.org/imx/20250918032555.3987157-1-hongxing.zhu@nxp.com/

Main change in v6:
- Refer to Krzysztof's comments, let i.MX95 PCIes has the "ref" clock
  since it is wired actually, and add one more optional "extref" clock
  for i.MX95 PCIes.
https://lore.kernel.org/imx/20250917045238.1048484-1-hongxing.zhu@nxp.com/

Main change in v5:
- Update the commit message of first patch refer to Bjorn's comments.
- Correct the typo error and update the description of property in the
  first patch.
https://lore.kernel.org/imx/20250915035348.3252353-1-hongxing.zhu@nxp.com/

Main change in v4:
- Add one more reference clock "extref" to be onhalf the reference clock
  that comes from external crystal oscillator.
https://lore.kernel.org/imx/20250626073804.3113757-1-hongxing.zhu@nxp.com/

Main change in v3:
- Update the logic check external reference clock mode is enabled or
  not in the driver codes.
https://lore.kernel.org/imx/20250620031350.674442-1-hongxing.zhu@nxp.com/

Main change in v2:
- Fix yamllint warning.
- Refine the driver codes.
https://lore.kernel.org/imx/20250619091004.338419-1-hongxing.zhu@nxp.com/

[PATCH v8 1/3] dt-bindings: PCI: dwc: Add external reference clock
[PATCH v8 2/3] dt-bindings: PCI: pci-imx6: Add external reference
[PATCH v8 3/3] PCI: imx6: Add external reference clock input mode

Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.yaml      |  3 +++
Documentation/devicetree/bindings/pci/snps,dw-pcie-common.yaml |  6 ++++++
drivers/pci/controller/dwc/pci-imx6.c                          | 19 ++++++++++++-------
3 files changed, 21 insertions(+), 7 deletions(-)