new file mode 100644
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+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
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> --- Changes for v4 - Add explanation for charger type and related doc at usb.org Changes for v3: - Change kernel version for 5.6, and delete the kernel printk time Documentation/ABI/testing/usb-charger-uevent | 46 ++++++++++++++++++++ 1 file changed, 46 insertions(+) create mode 100644 Documentation/ABI/testing/usb-charger-uevent