i.MX7D variant of the IP can use either Crystal Oscillator input
or internal clock input as a Reference Clock input for PCIe PHY.
Add support for an optional property 'pcie-phy-refclk-internal'.
If present then an internal clock input is used as PCIe PHY
reference clock source. By default an external oscillator input
is still used.

Verified on Compulab SBC-iMX7 Single Board Computer.

Signed-off-by: Ilya Ledvich <redacted>
---
 Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt | 5 +++++
 drivers/pci/dwc/pci-imx6.c                               | 8 +++++++-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt b/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt
index 7b1e48b..581bc09 100644
--- a/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt
+++ b/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt

@@ -50,6 +50,11 @@ Additional required properties for imx7d-pcie:
               - "pciephy"
               - "apps"

+Additional optional properties for imx7d-pcie:
+- pcie-phy-refclk-internal: If present then an internal PLL input is used as
+  PCIe PHY reference clock source. By default an external oscillator input
+  is used.