From: Robert Baldyga <r.baldyga@samsung.com>
To: cw00.choi@samsung.com
Cc: myungjoo.ham@samsung.com, rogerq@ti.com,
linux-usb@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org, m.szyprowski@samsung.com,
Robert Baldyga <r.baldyga@samsung.com>
Subject: [PATCH v2 4/4] Documentation: extcon: usb-gpio: update usb-gpio binding description
Date: Wed, 01 Apr 2015 09:23:25 +0200 [thread overview]
Message-ID: <1427873005-24024-5-git-send-email-r.baldyga@samsung.com> (raw)
In-Reply-To: <1427873005-24024-1-git-send-email-r.baldyga@samsung.com>
Add information about VBUS pin detection support, 'debounce' property
and some other details.
Signed-off-by: Robert Baldyga <r.baldyga@samsung.com>
---
.../devicetree/bindings/extcon/extcon-usb-gpio.txt | 28 ++++++++++++++++++++--
1 file changed, 26 insertions(+), 2 deletions(-)
diff --git a/Documentation/devicetree/bindings/extcon/extcon-usb-gpio.txt b/Documentation/devicetree/bindings/extcon/extcon-usb-gpio.txt
index af0b903..7096f39 100644
--- a/Documentation/devicetree/bindings/extcon/extcon-usb-gpio.txt
+++ b/Documentation/devicetree/bindings/extcon/extcon-usb-gpio.txt
@@ -1,16 +1,40 @@
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>;
}
&omap_dwc3_1 {
--
1.9.1
next prev parent reply other threads:[~2015-04-01 7:24 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-01 7:23 [PATCH v2 0/4] extcon: usb-gpio: fixes and improvements Robert Baldyga
2015-04-01 7:23 ` [PATCH v2 1/4] extcon: usb-gpio: register extcon device before IRQ registration Robert Baldyga
2015-04-01 11:58 ` Roger Quadros
2015-04-01 23:41 ` Chanwoo Choi
2015-04-01 7:23 ` [PATCH v2 2/4] extcon: usb-gpio: add support for VBUS detection Robert Baldyga
2015-04-01 11:28 ` Roger Quadros
2015-04-01 11:49 ` Robert Baldyga
2015-04-02 12:27 ` Roger Quadros
2015-04-01 7:23 ` [PATCH v2 3/4] extcon: usb-gpio: make debounce value configurable in devicetree Robert Baldyga
2015-04-01 11:32 ` Roger Quadros
2015-04-01 7:23 ` Robert Baldyga [this message]
2015-04-01 11:33 ` [PATCH v2 4/4] Documentation: extcon: usb-gpio: update usb-gpio binding description Roger Quadros
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