diff options
author | Robert Baldyga <r.baldyga@samsung.com> | 2015-04-01 09:23:25 +0200 |
---|---|---|
committer | Srinivas Kandagatla <srinivas.kandagatla@linaro.org> | 2015-04-07 12:19:56 +0100 |
commit | cebb8eb2f8ec9c644fabf3cee69a3637b766c003 (patch) | |
tree | 3cb5042e88e7c17999e452772218f17080503062 | |
parent | 0944d8ee6c2f7fb7b512b109280ad9d00cd80d98 (diff) |
Documentation: extcon: usb-gpio: update usb-gpio binding description
Add information about VBUS pin detection support, 'debounce' property
and some other details.
Signed-off-by: Robert Baldyga <r.baldyga@samsung.com>
-rw-r--r-- | Documentation/devicetree/bindings/extcon/extcon-usb-gpio.txt | 41 |
1 files changed, 33 insertions, 8 deletions
diff --git a/Documentation/devicetree/bindings/extcon/extcon-usb-gpio.txt b/Documentation/devicetree/bindings/extcon/extcon-usb-gpio.txt index 85fe6b067060..b368d45703a4 100644 --- a/Documentation/devicetree/bindings/extcon/extcon-usb-gpio.txt +++ b/Documentation/devicetree/bindings/extcon/extcon-usb-gpio.txt @@ -1,18 +1,43 @@ USB GPIO Extcon device -This is a virtual device used to generate USB cable states from the USB ID pin -connected to a GPIO pin. +This is a virtual device used to generate USB cable states from the USB +ID and VBUS signals connected to GPIO pins. + +The extcon cable states USB and USB_HOST are actually VBUS and !ID +pin states and do not indicate what mode the USB needs to operate in. +That decision is done by the USB stack. + +Some devices have only one of these GPIO pins, so we support cases when +only one of them is present. Hence properties 'id-gpio' and 'vbus-gpio' +are described as optional, but at least one of them has to be present +in extcon-usb-gpio node. + +In general we have three cases: +1. If VBUS and ID gpios are present we pass them as is + USB-HOST = !ID, USB = VBUS +2. If only VBUS gpio is present we assume that ID pin is always High. + USB-HOST = false, USB = VBUS. +3. If only ID pin is available we infer the VBUS pin states based on ID. + USB-HOST = !ID, USB = ID Required properties: - compatible: Should be "linux,extcon-usb-gpio" + +Optional properties - id-gpio: gpio for USB ID pin. See gpio binding. +- vbus-gpio: gpio for USB VBUS pin. See gpio binding. +- debounce: gpio debounce time in milliseconds (u32). + + +Example: Examples of extcon-usb-gpio node in dra7-evm.dts as listed below: + extcon_usb1 { + compatible = "linux,extcon-usb-gpio"; + id-gpio = <&gpio6 1 GPIO_ACTIVE_HIGH>; + vbus-gpio = <&gpio6 2 GPIO_ACTIVE_HIGH>; + debounce = <25>; + } -Example: - extcon_usb1 { - compatible = "linux,extcon-usb-gpio"; - id-gpio = <&gpio6 1 GPIO_ACTIVE_HIGH>; - } + &omap_dwc3_1 { - &omap_dwc3_1 { extcon = <&extcon_usb1>; }; |