linux-kernel - [PATCHv2 0/2] extcon: driver for Intel USB MUX

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Message-Id: <1449134991-39095-1-git-send-email-heikki.krogerus@linux.intel.com>
Date:	Thu,  3 Dec 2015 11:29:49 +0200
From:	Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To:	Chanwoo Choi <cw00.choi@...sung.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	MyungJoo Ham <myungjoo.ham@...sung.com>,
	David Cohen <david.a.cohen@...ux.intel.com>,
	Lu Baolu <baolu.lu@...ux.intel.com>,
	Mathias Nyman <mathias.nyman@...ux.intel.com>,
	Felipe Balbi <balbi@...com>, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCHv2 0/2] extcon: driver for Intel USB MUX

Changes since v1:
- Using xhci_find_next_ext_cap() as suggested by Baolu
- Protection agains unbalanced uregistering as suggested by David Cohen

Hi,

This is a driver for an internal mux which is available on most modern
Intel platforms that shares an USB port between USB Device Controller
and xHCI. Normally BIOS or ACPI take care of it, but on some platforms
that is not possible, and the OS has to control it.

When the mux needs to be handled by OS, there is always an external
component that detects connection changes in the port behind the mux,
for example PMIC. The driver for that component needs to notify this
driver. The mux itself has no means to detect connection changes on
the port. User selectable kconfig option is deliberately left out. The
driver for the mux needs to be always selected by the drivers for the
component that can notify the mux driver about connection changes.

The only platforms the need the OS to be in control of the mux so far
are Cherrytrail based, and on Cherrytrail SOC the mux control
registers are mapped to xHCI MMIO. The second patch will register an
instance of the mux from pci_quirks.c if the mux is detected and if
the driver has been loaded.

The mux control registers are defined in Cherrytrail datasheets [1]
page 2230-2234.

I think these should go via extcon tree, but it's up to you guys of
course.

[1] http://www.intel.es/content/www/es/es/processors/atom/atom-z8000-datasheet-vol-2.html

Heikki Krogerus (2):
  extcon: add driver for Intel USB mux
  usb: pci-quirks: register USB mux found on Cherrytrail SOC

 drivers/extcon/Kconfig               |   5 ++
 drivers/extcon/Makefile              |   1 +
 drivers/extcon/extcon-intel-usb.c    | 118 +++++++++++++++++++++++++++++++++++
 drivers/usb/host/pci-quirks.c        |  26 +++++++-
 include/linux/extcon/intel_usb_mux.h |  31 +++++++++
 5 files changed, 180 insertions(+), 1 deletion(-)
 create mode 100644 drivers/extcon/extcon-intel-usb.c
 create mode 100644 include/linux/extcon/intel_usb_mux.h

-- 
2.6.2

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