Extcon: support multiple states at a device.
One switch device (e.g., MUIC(MAX8997, MAX77686, ...), and some 30-pin
devices) may have multiple cables attached. For example, one
30-pin port may inhabit a USB cable, an HDMI cable, and a mic.
Thus, one switch device requires multiple state bits each representing
a type of cable.
For such purpose, we use the 32bit state variable; thus, up to 32
different type of cables may be defined for a switch device. The list of
possible cables is defined by the array of cable names in the switch_dev
struct given to the class.
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
--
Changes from V7
- Bugfixed in _call_per_cable() (incorrect nb) (Chanwoo Choi)
- Compiler error in header for !CONFIG_EXTCON (Chanwoo Choi)
Changes from V5
- Sysfs style reformed: subdirectory per cable.
- Updated standard cable names
- Removed unnecessary printf
- Bugfixes after testing
Changes from V4
- Bugfixes after more testing at Exynos4412 boards with userspace
processses.
Changes from V3
- Bugfixes after more testing at Exynos4412 boards.
Changes from V2
- State can be stored by user
- Documentation updated
Changes from RFC
- Switch is renamed to extcon
- Added kerneldoc comments
- Added APIs to support "standard" cable names
- Added helper APIs to support notifier block registration with cable
name.
- Regrouped function list in the header file.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/Documentation/ABI/testing/sysfs-class-extcon b/Documentation/ABI/testing/sysfs-class-extcon
index 59a4b1c..19b18e9 100644
--- a/Documentation/ABI/testing/sysfs-class-extcon
+++ b/Documentation/ABI/testing/sysfs-class-extcon
@@ -1,5 +1,5 @@
What: /sys/class/extcon/.../
-Date: December 2011
+Date: February 2012
Contact: MyungJoo Ham <myungjoo.ham@samsung.com>
Description:
Provide a place in sysfs for the extcon objects.
@@ -7,8 +7,16 @@
The name of extcon object denoted as ... is the name given
with extcon_dev_register.
+ One extcon device denotes a single external connector
+ port. An external connector may have multiple cables
+ attached simultaneously. Many of docks, cradles, and
+ accessory cables have such capability. For example,
+ the 30-pin port of Nuri board (/arch/arm/mach-exynos)
+ may have both HDMI and Charger attached, or analog audio,
+ video, and USB cables attached simulteneously.
+
What: /sys/class/extcon/.../name
-Date: December 2011
+Date: February 2012
Contact: MyungJoo Ham <myungjoo.ham@samsung.com>
Description:
The /sys/class/extcon/.../name shows the name of the extcon
@@ -17,10 +25,51 @@
this sysfs node.
What: /sys/class/extcon/.../state
-Date: December 2011
+Date: February 2012
Contact: MyungJoo Ham <myungjoo.ham@samsung.com>
Description:
- The /sys/class/extcon/.../state shows the cable attach/detach
- information of the corresponding extcon object. If the extcon
- objecct has an optional callback "show_state" defined, the
- callback will provide the name with this sysfs node.
+ The /sys/class/extcon/.../state shows and stores the cable
+ attach/detach information of the corresponding extcon object.
+ If the extcon object has an optional callback "show_state"
+ defined, the showing function is overriden with the optional
+ callback.
+
+ If the default callback for showing function is used, the
+ format is like this:
+ # cat state
+ USB_OTG=1
+ HDMI=0
+ TA=1
+ EAR_JACK=0
+ #
+ In this example, the extcon device have USB_OTG and TA
+ cables attached and HDMI and EAR_JACK cables detached.
+
+ In order to update the state of an extcon device, enter a hex
+ state number starting with 0x.
+ echo 0xHEX > state
+
+ This updates the whole state of the extcon dev.
+ Inputs of all the methods are required to meet the
+ mutually_exclusive contidions if they exist.
+
+ It is recommended to use this "global" state interface if
+ you need to enter the value atomically. The later state
+ interface associated with each cable cannot update
+ multiple cable states of an extcon device simultaneously.
+
+What: /sys/class/extcon/.../cable.x/name
+Date: February 2012
+Contact: MyungJoo Ham <myungjoo.ham@samsung.com>
+Description:
+ The /sys/class/extcon/.../cable.x/name shows the name of cable
+ "x" (integer between 0 and 31) of an extcon device.
+
+What: /sys/class/extcon/.../cable.x/state
+Date: February 2012
+Contact: MyungJoo Ham <myungjoo.ham@samsung.com>
+Description:
+ The /sys/class/extcon/.../cable.x/name shows and stores the
+ state of cable "x" (integer between 0 and 31) of an extcon
+ device. The state value is either 0 (detached) or 1
+ (attached).