twl4030_charger: allow max_current to be managed via sysfs.

'max_current' sysfs attributes are created which allow the
max to be set.
Whenever a current source changes, the default is restored.
This will be followed by a uevent, so user-space can decide to
update again.

Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: NeilBrown <neil@brown.name>
Signed-off-by: Sebastian Reichel <sre@kernel.org>
diff --git a/Documentation/ABI/testing/sysfs-class-power-twl4030 b/Documentation/ABI/testing/sysfs-class-power-twl4030
new file mode 100644
index 0000000..0331bba
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-power-twl4030
@@ -0,0 +1,15 @@
+What: /sys/class/power_supply/twl4030_ac/max_current
+      /sys/class/power_supply/twl4030_usb/max_current
+Description:
+	Read/Write limit on current which may
+	be drawn from the ac (Accessory Charger) or
+	USB port.
+
+	Value is in micro-Amps.
+
+	Value is set automatically to an appropriate
+	value when a cable is plugged or unplugged.
+
+	Value can the set by writing to the attribute.
+	The change will only persist until the next
+	plug event.  These event are reported via udev.