RFC usb: xhci: Introduce xhci-snps

Synopsys DWC_usb3x IPs are used on many different platforms. Since they share the same IP, often the quirks are common across different platforms and versions. This drives the need to find a way to handle all the common (and platform specific) quirks and separate its logic from dwc3 and xhci core logic. Hopefully it can also reduce introducing new device properties while maintaining abstraction.

So, let's create a xhci-snps glue extension that can apply to xhci-plat and xhci-pci glue drivers and teach it to handle DWC_usb3x hosts. For this particular change, we'll start with xhci-plat glue driver.

NOTE: This is a quick implementation of how I'd imagine to handle this. I apologize if it may lack documentation. It doesn't have all the common quirks added. I'd like to receive some feedbacks before moving forward.

Many thanks!
Thinh

Thinh Nguyen (4):
dt-bindings: usb: usb-xhci: Add xhci-snps-quirks
usb: dwc3: host: Always set xhci-snps-quirks
usb: dwc3: core: Share global register access with xhci driver
usb: xhci: Introduce Synopsys glue extension for DWC_usb3x

 .../devicetree/bindings/usb/usb-xhci.yaml     |   4 +
 drivers/usb/dwc3/core.c                       |   4 +-
 drivers/usb/dwc3/host.c                       |   4 +-
 drivers/usb/host/Kconfig                      |   8 +
 drivers/usb/host/Makefile                     |   3 +
 drivers/usb/host/xhci-plat.c                  |  40 ++++
 drivers/usb/host/xhci-plat.h                  |   3 +
 drivers/usb/host/xhci-snps.c                  | 185 ++++++++++++++++++
 drivers/usb/host/xhci-snps.h                  |  32 +++
 9 files changed, 280 insertions(+), 3 deletions(-)
 create mode 100644 drivers/usb/host/xhci-snps.c
 create mode 100644 drivers/usb/host/xhci-snps.h

base-commit: 97fa5887cf283bb75ffff5f6b2c0e71794c02400

2.28.0