Doc: ABI: add usb charger uevent

When the USB charger is inserted or removed, the users could get
USB charger state and type through the uevent.

Signed-off-by: Peter Chen <peter.chen@nxp.com>
Link: https://lore.kernel.org/r/1579145333-1657-2-git-send-email-peter.chen@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/Documentation/ABI/testing/usb-charger-uevent b/Documentation/ABI/testing/usb-charger-uevent
new file mode 100644 (file)
index 0000000..419a92d
--- /dev/null
+++ b/Documentation/ABI/testing/usb-charger-uevent
@@ -0,0 +1,46 @@
+What:          Raise a uevent when a USB charger is inserted or removed
+Date:          2020-01-14
+KernelVersion: 5.6
+Contact:       linux-usb@vger.kernel.org
+Description:   There are two USB charger states:
+               USB_CHARGER_ABSENT
+               USB_CHARGER_PRESENT
+               There are five USB charger types:
+               USB_CHARGER_UNKNOWN_TYPE: Charger type is unknown
+               USB_CHARGER_SDP_TYPE: Standard Downstream Port
+               USB_CHARGER_CDP_TYPE: Charging Downstream Port
+               USB_CHARGER_DCP_TYPE: Dedicated Charging Port
+               USB_CHARGER_ACA_TYPE: Accessory Charging Adapter
+               https://www.usb.org/document-library/battery-charging-v12-spec-and-adopters-agreement
+
+               Here are two examples taken using udevadm monitor -p when
+               USB charger is online:
+               UDEV  change   /devices/soc0/usbphynop1 (platform)
+               ACTION=change
+               DEVPATH=/devices/soc0/usbphynop1
+               DRIVER=usb_phy_generic
+               MODALIAS=of:Nusbphynop1T(null)Cusb-nop-xceiv
+               OF_COMPATIBLE_0=usb-nop-xceiv
+               OF_COMPATIBLE_N=1
+               OF_FULLNAME=/usbphynop1
+               OF_NAME=usbphynop1
+               SEQNUM=2493
+               SUBSYSTEM=platform
+               USB_CHARGER_STATE=USB_CHARGER_PRESENT
+               USB_CHARGER_TYPE=USB_CHARGER_SDP_TYPE
+               USEC_INITIALIZED=227422826
+
+               USB charger is offline:
+               KERNEL change   /devices/soc0/usbphynop1 (platform)
+               ACTION=change
+               DEVPATH=/devices/soc0/usbphynop1
+               DRIVER=usb_phy_generic
+               MODALIAS=of:Nusbphynop1T(null)Cusb-nop-xceiv
+               OF_COMPATIBLE_0=usb-nop-xceiv
+               OF_COMPATIBLE_N=1
+               OF_FULLNAME=/usbphynop1
+               OF_NAME=usbphynop1
+               SEQNUM=2494
+               SUBSYSTEM=platform
+               USB_CHARGER_STATE=USB_CHARGER_ABSENT
+               USB_CHARGER_TYPE=USB_CHARGER_UNKNOWN_TYPE