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There could be cables that t recannot be attaches simulatenously. Extcon
device drivers may express such information via mutually_exclusive in
struct extcon_dev.
For example, for an extcon device with 16 cables (bits 0 to 15 are
available), if mutually_exclusive = { 0x7, 0xC0, 0x81, 0 }, then, the
following attachments are prohibitted.
{0, 1}
{0, 2}
{1, 2}
{6, 7}
{0, 7}
and every attachment set that are superset of one of the above.
For the detail, please refer to linux/include/linux/extcon.h.
The concept is suggested by NeilBrown <neilb@suse.de>
Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
--
Changes from V5:
- Updated sysfs format
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
98 lines
3.3 KiB
Plaintext
98 lines
3.3 KiB
Plaintext
What: /sys/class/extcon/.../
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Date: February 2012
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Contact: MyungJoo Ham <myungjoo.ham@samsung.com>
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Description:
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Provide a place in sysfs for the extcon objects.
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This allows accessing extcon specific variables.
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The name of extcon object denoted as ... is the name given
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with extcon_dev_register.
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One extcon device denotes a single external connector
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port. An external connector may have multiple cables
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attached simultaneously. Many of docks, cradles, and
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accessory cables have such capability. For example,
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the 30-pin port of Nuri board (/arch/arm/mach-exynos)
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may have both HDMI and Charger attached, or analog audio,
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video, and USB cables attached simulteneously.
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If there are cables mutually exclusive with each other,
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such binary relations may be expressed with extcon_dev's
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mutually_exclusive array.
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What: /sys/class/extcon/.../name
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Date: February 2012
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Contact: MyungJoo Ham <myungjoo.ham@samsung.com>
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Description:
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The /sys/class/extcon/.../name shows the name of the extcon
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object. If the extcon object has an optional callback
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"show_name" defined, the callback will provide the name with
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this sysfs node.
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What: /sys/class/extcon/.../state
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Date: February 2012
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Contact: MyungJoo Ham <myungjoo.ham@samsung.com>
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Description:
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The /sys/class/extcon/.../state shows and stores the cable
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attach/detach information of the corresponding extcon object.
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If the extcon object has an optional callback "show_state"
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defined, the showing function is overriden with the optional
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callback.
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If the default callback for showing function is used, the
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format is like this:
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# cat state
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USB_OTG=1
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HDMI=0
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TA=1
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EAR_JACK=0
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#
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In this example, the extcon device have USB_OTG and TA
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cables attached and HDMI and EAR_JACK cables detached.
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In order to update the state of an extcon device, enter a hex
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state number starting with 0x.
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echo 0xHEX > state
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This updates the whole state of the extcon dev.
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Inputs of all the methods are required to meet the
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mutually_exclusive contidions if they exist.
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It is recommended to use this "global" state interface if
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you need to enter the value atomically. The later state
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interface associated with each cable cannot update
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multiple cable states of an extcon device simultaneously.
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What: /sys/class/extcon/.../cable.x/name
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Date: February 2012
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Contact: MyungJoo Ham <myungjoo.ham@samsung.com>
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Description:
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The /sys/class/extcon/.../cable.x/name shows the name of cable
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"x" (integer between 0 and 31) of an extcon device.
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What: /sys/class/extcon/.../cable.x/state
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Date: February 2012
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Contact: MyungJoo Ham <myungjoo.ham@samsung.com>
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Description:
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The /sys/class/extcon/.../cable.x/name shows and stores the
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state of cable "x" (integer between 0 and 31) of an extcon
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device. The state value is either 0 (detached) or 1
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(attached).
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What: /sys/class/extcon/.../mutually_exclusive/...
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Date: December 2011
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Contact: MyungJoo Ham <myungjoo.ham@samsung.com>
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Description:
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Shows the relations of mutually exclusiveness. For example,
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if the mutually_exclusive array of extcon_dev is
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{0x3, 0x5, 0xC, 0x0}, the, the output is:
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# ls mutually_exclusive/
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0x3
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0x5
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0xc
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#
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Note that mutually_exclusive is a sub-directory of the extcon
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device and the file names under the mutually_exclusive
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directory show the mutually-exclusive sets, not the contents
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of the files.
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