Introduce usb charger framework to deal with the usb gadget power negotation

From: Baolin Wang <[email protected]>

Currently the Linux kernel does not provide any standard integration of this feature that integrates the USB subsystem with the system power regulation provided by PMICs meaning that either vendors must add this in their kernels or USB gadget devices based on Linux (such as mobile phones) may not behave as they should. Thus provide a standard framework for doing this in kernel.

Now introduce one user with wm831x_power to support and test the usb charger, which is pending testing. Moreover there may be other potential users will use it in future.

Changes since v10:
- Introduce usb_charger_get_state() function to check charger state.
- Remove the mutex lock in usb_charger_set_cur_limit_by_type() function in case will be issued in atomic context.

Baolin Wang (4):
gadget: Introduce the usb charger framework
gadget: Support for the usb charger framework
gadget: Integrate with the usb gadget supporting for usb charger
power: wm831x_power: Support USB charger current limit management

 drivers/power/wm831x_power.c      |   69 ++++
 drivers/usb/gadget/Kconfig        |    7 +
 drivers/usb/gadget/udc/Makefile   |    1 +
 drivers/usb/gadget/udc/charger.c  |  807 +++++++++++++++++++++++++++++++++++++
 drivers/usb/gadget/udc/udc-core.c |   11 +
 include/linux/mfd/wm831x/pdata.h  |    3 +
 include/linux/usb/charger.h       |  191 +++++++++
 include/linux/usb/gadget.h        |   11 +
 include/uapi/linux/usb/charger.h  |   31 ++
 9 files changed, 1131 insertions(+)
 create mode 100644 drivers/usb/gadget/udc/charger.c
 create mode 100644 include/linux/usb/charger.h
 create mode 100644 include/uapi/linux/usb/charger.h

1.7.9.5

This patch introduces the usb charger driver based on usb gadget that makes an enhancement to a power driver. It works well in practice but that requires a system with suitable hardware.

The basic conception of the usb charger is that, when one usb charger is added or removed by reporting from the usb gadget state change or the extcon device state change, the usb charger will report to power user to set the current limitation.

The usb charger will register notifiees on the usb gadget or the extcon device to get notified the usb charger state. It also supplies the notification mechanism to userspace When the usb charger state is changed.

Power user will register a notifiee on the usb charger to get notified by status changes from the usb charger. It will report to power user to set the current limitation when detecting the usb charger is added or removed from extcon device state or usb gadget state.

This patch doesn't yet integrate with the gadget code, so some functions which rely on the 'gadget' are not completed, that will be implemented in the following patches.

---
 drivers/usb/gadget/Kconfig       |    7 +
 drivers/usb/gadget/udc/Makefile  |    1 +
 drivers/usb/gadget/udc/charger.c |  770 ++++++++++++++++++++++++++++++++++++++
 include/linux/usb/charger.h      |  191 ++++++++++
 include/uapi/linux/usb/charger.h |   31 ++
 5 files changed, 1000 insertions(+)
 create mode 100644 drivers/usb/gadget/udc/charger.c
 create mode 100644 include/linux/usb/charger.h
 create mode 100644 include/uapi/linux/usb/charger.h

index 2057add..89f4e9b 100644
@@ -134,6 +134,13 @@ config U_SERIAL_CONSOLE
 	help
 	   It supports the serial gadget can be used as a console.
 
+config USB_CHARGER
+	bool "USB charger support"
+	help
+	  The usb charger driver based on the usb gadget that makes an
+	  enhancement to a power driver which can set the current limitation
+	  when the usb charger is added or removed.
+
 source "drivers/usb/gadget/udc/Kconfig"
 
 #

index dfee534..0e9564c 100644
@@ -2,6 +2,7 @@
 # USB peripheral controller drivers
 #
 obj-$(CONFIG_USB_GADGET)	+= udc-core.o
+obj-$(CONFIG_USB_CHARGER)	+= charger.o
 obj-$(CONFIG_USB_DUMMY_HCD)	+= dummy_hcd.o
 obj-$(CONFIG_USB_NET2272)	+= net2272.o
 obj-$(CONFIG_USB_NET2280)	+= net2280.o

new file mode 100644
index 0000000..3c56ec4
@@ -0,0 +1,31 @@
+/*
+ * This file defines the USB charger type and state that are needed for
+ * USB device APIs.
+ */
+
+#ifndef _UAPI__LINUX_USB_CHARGER_H
+#define _UAPI__LINUX_USB_CHARGER_H
+
+/*
+ * USB charger type:
+ * SDP (Standard Downstream Port)
+ * DCP (Dedicated Charging Port)
+ * CDP (Charging Downstream Port)
+ * ACA (Accessory Charger Adapters)
+ */
+enum usb_charger_type {
+	UNKNOWN_TYPE,
+	SDP_TYPE,
+	DCP_TYPE,
+	CDP_TYPE,
+	ACA_TYPE,
+};
+
+/* USB charger state */
+enum usb_charger_state {
+	USB_CHARGER_DEFAULT,
+	USB_CHARGER_PRESENT,
+	USB_CHARGER_REMOVE,
+};
+
+#endif /* _UAPI__LINUX_USB_CHARGER_H */

1.7.9.5