[PATCH v8 0/7] usb: add support for Intel dual role port mux

[Lu Baolu]

Intel SOC chips are featured with USB dual role. The host role
is provided by Intel xHCI IP, and the gadget role is provided
by IP from designware. Tablet platform designs always share a
single port for both host and gadget controllers.  There is a
mux to switch the port to the right controller according to the
cable type. OS needs to provide the callback to control the mux
when a plug-in event raises. The method to control the mux is
platform dependent. At least three types of implementation can
be found across current devices. 1) GPIO pins; 2) a unit which
can be controlled by memory mapped registers; 3) ACPI ASL code.

This patch series adds supports for Intel dual role port mux.
It includes:
(1) A helper layer on top of extcon for individual mux driver.
    It listens to the USB-HOST extcon cable and call the switch
    call-back when the cable state changes.
(2) Drivers for GPIO controlled port mux which could be found
    on Baytrail devices. A mfd driver is used to split the GPIOs
    into a USB gpio extcon device, a fixed regulator for gpio
    controlled USB VCC, and a USB mux device. Driver for USB
    gpio extcon device is already in upstream Linux. This patch
    series includes a driver for GPIO USB mux.
(3) Drivers for USB port mux controlled through memory mapped
    registers and the logic to create the mux device. This type
    of dual role port mux could be found in Cherry Trail and
    Broxton devices.

Lu Baolu (7):
  regulator: fixed: add support for ACPI interface
  usb: mux: add generic code for dual role port mux
  usb: mux: add driver for Intel gpio controlled port mux
  usb: mux: add driver for Intel drcfg controlled port mux
  mfd: intel_vuport: Add Intel virtual USB port MFD Driver
  usb: pci-quirks: add Intel USB drcfg mux device
  MAINTAINERS: add maintainer entry for Intel USB dual role mux drivers

Change log:

v7->v8:
 - In patch "regulator: fixed: add support for ACPI interface", the
   fixed regulator gpio name has been changed to "gpio".
 - In patch "MAINTAINERS: add maintainer entry for Intel USB dual role
   mux drivers", filenames have been updated.

v6->v7:
 - Two patches have been picked up by extcon maintainer. Hence,
   remove them since this version.
   - extcon: usb-gpio: add device binding for platform device
   - extcon: usb-gpio: add support for ACPI gpio interface
 - Below patch has been removed from this series because it's unnecessary.
   - regulator: fixed: add device binding for platform device
 - In patch "regulator: fixed: add support for ACPI interface",
   a static gpio name is used to get the regulator gpio.
 - In patch "mfd: intel_vuport: Add Intel virtual USB port MFD Driver",
   unnecessary "gpio-name" string property has been removed.

v5->v6:
 Work internally with Felipe to improve the whole patch series.
 Below changes have been made since last version.
 - rework the common code to make it a generic interface for mux devices;
 - split the vbus gpio handling to a fixed regulator device;
 - removed unnecessary filtering for state change;
 - removed unnecessary WARN statement;
 - removed globals in mux drivers;
 - removed unnecessary register polling and waiting in drcfg driver;

v4->v5:
 - Change the extcon interfaces with the new ones suggested by
   2a9de9c0f08d6 (extcon: Use the unique id for external connector
   instead of string)
 - remove patch "usb: pci-quirks: add Intel USB drcfg mux device"
   from this serial due to that it's not driver staff. Will be
   submitted seperately.

v3->v4:
 - Check all patches with "checkpatch.pl --strict", and fix all
   CHECKs;
 - Change sysfs node from "intel_mux" to "port_mux";
 - Refines below confusing functions:
   intel_usb_mux_register() -> intel_usb_mux_bind_cable()
   intel_usb_mux_unregister() -> intel_usb_mux_unbind_cable();
 - Remove unnecessary struct intel_mux_dev.

v2->v3:
 - uvport mfd driver got reviewed by Lee Jones, the following
   changes were made accordingly.
 - seperate uvport driver from the mux drivers in MAINTAINERS file
 - refine the description in Kconfig
 - refine the mfd_cell structure data

v1->v2:
 - move mux driver from drivers/usb/misc to drivers/usb/mux;
 - replace debugfs with sysfs for user level mux control;
 - remove unnecessary register restore if mux registeration failed;
 - Add "Acked-by: Chanwoo Choi <cw00.choi@xxxxxxxxxxx>" to extcon changes;
 - Make the file names and exported function names more specific;
 - Remove the usb_mux_get_dev() interface;
 - Move "struct intel_usb_mux" from .h to .c file;
 - Fix various kbuild robot warnings.

 Documentation/ABI/testing/sysfs-bus-platform |  17 +++
 MAINTAINERS                                  |  10 ++
 drivers/mfd/Kconfig                          |   8 +
 drivers/mfd/Makefile                         |   1 +
 drivers/mfd/intel-vuport.c                   |  89 +++++++++++
 drivers/regulator/fixed.c                    |  46 ++++++
 drivers/usb/Kconfig                          |   2 +
 drivers/usb/Makefile                         |   1 +
 drivers/usb/host/pci-quirks.c                |  45 +++++-
 drivers/usb/host/xhci-ext-caps.h             |   2 +
 drivers/usb/mux/Kconfig                      |  30 ++++
 drivers/usb/mux/Makefile                     |   6 +
 drivers/usb/mux/portmux-core.c               | 217 +++++++++++++++++++++++++++
 drivers/usb/mux/portmux-intel-drcfg.c        | 171 +++++++++++++++++++++
 drivers/usb/mux/portmux-intel-gpio.c         | 149 ++++++++++++++++++
 include/linux/usb/portmux.h                  |  78 ++++++++++
 16 files changed, 870 insertions(+), 2 deletions(-)
 create mode 100644 drivers/mfd/intel-vuport.c
 create mode 100644 drivers/usb/mux/Kconfig
 create mode 100644 drivers/usb/mux/Makefile
 create mode 100644 drivers/usb/mux/portmux-core.c
 create mode 100644 drivers/usb/mux/portmux-intel-drcfg.c
 create mode 100644 drivers/usb/mux/portmux-intel-gpio.c
 create mode 100644 include/linux/usb/portmux.h

-- 
2.1.4