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Diffstat (limited to 'kernel/Documentation/ABI/testing/sysfs-class-extcon')
| -rw-r--r-- | kernel/Documentation/ABI/testing/sysfs-class-extcon | 97 |
1 files changed, 97 insertions, 0 deletions
diff --git a/kernel/Documentation/ABI/testing/sysfs-class-extcon b/kernel/Documentation/ABI/testing/sysfs-class-extcon new file mode 100644 index 000000000..57a726232 --- /dev/null +++ b/kernel/Documentation/ABI/testing/sysfs-class-extcon @@ -0,0 +1,97 @@ +What: /sys/class/extcon/.../ +Date: February 2012 +Contact: MyungJoo Ham <myungjoo.ham@samsung.com> +Description: + Provide a place in sysfs for the extcon objects. + This allows accessing extcon specific variables. + 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 simultaneously. + + If there are cables mutually exclusive with each other, + such binary relations may be expressed with extcon_dev's + mutually_exclusive array. + +What: /sys/class/extcon/.../name +Date: February 2012 +Contact: MyungJoo Ham <myungjoo.ham@samsung.com> +Description: + The /sys/class/extcon/.../name shows the name of the extcon + object. If the extcon object has an optional callback + "show_name" defined, the callback will provide the name with + this sysfs node. + +What: /sys/class/extcon/.../state +Date: February 2012 +Contact: MyungJoo Ham <myungjoo.ham@samsung.com> +Description: + 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 overridden 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 has 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 device. + Inputs of all the methods are required to meet the + mutually_exclusive conditions if they exist. + + It is recommended to use this "global" state interface if + you need to set 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/state 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). + +What: /sys/class/extcon/.../mutually_exclusive/... +Date: December 2011 +Contact: MyungJoo Ham <myungjoo.ham@samsung.com> +Description: + Shows the relations of mutually exclusiveness. For example, + if the mutually_exclusive array of extcon device is + {0x3, 0x5, 0xC, 0x0}, then the output is: + # ls mutually_exclusive/ + 0x3 + 0x5 + 0xc + # + + Note that mutually_exclusive is a sub-directory of the extcon + device and the file names under the mutually_exclusive + directory show the mutually-exclusive sets, not the contents + of the files. |