[PATCH v4 2/5] gadget: Introduce the usb charger framework

[Baolin Wang]

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.

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.

Signed-off-by: Baolin Wang 
---
 drivers/usb/gadget/Kconfig  |   7 +
 drivers/usb/gadget/Makefile |   1 +
 drivers/usb/gadget/charger.c| 529 
 include/linux/usb/usb_charger.h | 138 +++
 4 files changed, 675 insertions(+)
 create mode 100644 drivers/usb/gadget/charger.c
 create mode 100644 include/linux/usb/usb_charger.h

diff --git a/drivers/usb/gadget/Kconfig b/drivers/usb/gadget/Kconfig
index bcf83c0..3d2b959 100644
--- a/drivers/usb/gadget/Kconfig
+++ b/drivers/usb/gadget/Kconfig
@@ -127,6 +127,13 @@ config USB_GADGET_STORAGE_NUM_BUFFERS
   a module parameter as well.
   If unsure, say 2.
 
+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"
 
 #
diff --git a/drivers/usb/gadget/Makefile b/drivers/usb/gadget/Makefile
index 598a67d..1e421c1 100644
--- a/drivers/usb/gadget/Makefile
+++ b/drivers/usb/gadget/Makefile
@@ -10,3 +10,4 @@ libcomposite-y:= usbstring.o config.o 
epautoconf.o
 libcomposite-y += composite.o functions.o configfs.o u_f.o
 
 obj-$(CONFIG_USB_GADGET)   += udc/ function/ legacy/
+obj-$(CONFIG_USB_CHARGER)  += charger.o
diff --git a/drivers/usb/gadget/charger.c b/drivers/usb/gadget/charger.c
new file mode 100644
index 000..35b46c1
--- /dev/null
+++ b/drivers/usb/gadget/charger.c
@@ -0,0 +1,529 @@
+/*
+ * charger.c -- USB charger driver
+ *
+ * Copyright (C) 2015 Linaro Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+
+#define DEFAULT_CUR_PROTECT(50)
+#define DEFAULT_SDP_CUR_LIMIT  (500 - DEFAULT_CUR_PROTECT)
+#define DEFAULT_DCP_CUR_LIMIT  (1500 - DEFAULT_CUR_PROTECT)
+#define DEFAULT_CDP_CUR_LIMIT  (1500 - DEFAULT_CUR_PROTECT)
+#define DEFAULT_ACA_CUR_LIMIT  (1500 - DEFAULT_CUR_PROTECT)
+
+static DEFINE_IDA(usb_charger_ida);
+static struct bus_type usb_charger_subsys = {
+   .name   = "usb-charger",
+   .dev_name   = "usb-charger",
+};
+
+static struct usb_charger *dev_to_uchger(struct device *udev)
+{
+   return container_of(udev, struct usb_charger, dev);
+}
+
+static ssize_t cur_limit_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+   struct usb_charger *uchger = dev_to_uchger(dev);
+
+   return scnprintf(buf, PAGE_SIZE, "%d %d %d %d\n",
+uchger->cur_limit.sdp_cur_limit,
+uchger->cur_limit.dcp_cur_limit,
+uchger->cur_limit.cdp_cur_limit,
+uchger->cur_limit.aca_cur_limit);
+}
+
+static ssize_t cur_limit_store(struct device *dev,
+  struct device_attribute *attr,
+  const char *buf, size_t count)
+{
+   struct usb_charger *uchger = dev_to_uchger(dev);
+   struct usb_charger_cur_limit cur;
+   int ret;
+
+   ret = sscanf(buf, "%d %d %d %d",
+_cur_limit, _cur_limit,
+_cur_limit, _cur_limit);
+   if (ret == 0)
+   return -EINVAL;
+
+   ret = usb_charger_set_cur_limit(uchger, );
+   if (ret < 0)
+   return ret;
+
+   return count;
+}
+static DEVICE_ATTR_RW(cur_limit);
+
+static struct attribute *usb_charger_attrs[] = {
+   _attr_cur_limit.attr,
+   NULL
+};
+ATTRIBUTE_GROUPS(usb_charger);
+
+/*
+ * usb_charger_find_by_name - Get the usb charger device by name.
+ * @name - usb charger device name.
+ *
+ * return the instance of usb charger device, the device must be
+ * released with 

[PATCH v4 2/5] gadget: Introduce the usb charger framework

[Baolin Wang]

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.

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.

Signed-off-by: Baolin Wang baolin.w...@linaro.org
---
 drivers/usb/gadget/Kconfig  |7 +
 drivers/usb/gadget/Makefile |1 +
 drivers/usb/gadget/charger.c|  529 +++
 include/linux/usb/usb_charger.h |  138 ++
 4 files changed, 675 insertions(+)
 create mode 100644 drivers/usb/gadget/charger.c
 create mode 100644 include/linux/usb/usb_charger.h

diff --git a/drivers/usb/gadget/Kconfig b/drivers/usb/gadget/Kconfig
index bcf83c0..3d2b959 100644
--- a/drivers/usb/gadget/Kconfig
+++ b/drivers/usb/gadget/Kconfig
@@ -127,6 +127,13 @@ config USB_GADGET_STORAGE_NUM_BUFFERS
   a module parameter as well.
   If unsure, say 2.
 
+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
 
 #
diff --git a/drivers/usb/gadget/Makefile b/drivers/usb/gadget/Makefile
index 598a67d..1e421c1 100644
--- a/drivers/usb/gadget/Makefile
+++ b/drivers/usb/gadget/Makefile
@@ -10,3 +10,4 @@ libcomposite-y:= usbstring.o config.o 
epautoconf.o
 libcomposite-y += composite.o functions.o configfs.o u_f.o
 
 obj-$(CONFIG_USB_GADGET)   += udc/ function/ legacy/
+obj-$(CONFIG_USB_CHARGER)  += charger.o
diff --git a/drivers/usb/gadget/charger.c b/drivers/usb/gadget/charger.c
new file mode 100644
index 000..35b46c1
--- /dev/null
+++ b/drivers/usb/gadget/charger.c
@@ -0,0 +1,529 @@
+/*
+ * charger.c -- USB charger driver
+ *
+ * Copyright (C) 2015 Linaro Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include linux/device.h
+#include linux/err.h
+#include linux/extcon.h
+#include linux/export.h
+#include linux/kernel.h
+#include linux/module.h
+#include linux/of.h
+#include linux/of_device.h
+#include linux/of_address.h
+#include linux/platform_device.h
+#include linux/slab.h
+#include linux/usb.h
+#include linux/usb/ch9.h
+#include linux/usb/gadget.h
+#include linux/usb/usb_charger.h
+
+#define DEFAULT_CUR_PROTECT(50)
+#define DEFAULT_SDP_CUR_LIMIT  (500 - DEFAULT_CUR_PROTECT)
+#define DEFAULT_DCP_CUR_LIMIT  (1500 - DEFAULT_CUR_PROTECT)
+#define DEFAULT_CDP_CUR_LIMIT  (1500 - DEFAULT_CUR_PROTECT)
+#define DEFAULT_ACA_CUR_LIMIT  (1500 - DEFAULT_CUR_PROTECT)
+
+static DEFINE_IDA(usb_charger_ida);
+static struct bus_type usb_charger_subsys = {
+   .name   = usb-charger,
+   .dev_name   = usb-charger,
+};
+
+static struct usb_charger *dev_to_uchger(struct device *udev)
+{
+   return container_of(udev, struct usb_charger, dev);
+}
+
+static ssize_t cur_limit_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+   struct usb_charger *uchger = dev_to_uchger(dev);
+
+   return scnprintf(buf, PAGE_SIZE, %d %d %d %d\n,
+uchger-cur_limit.sdp_cur_limit,
+uchger-cur_limit.dcp_cur_limit,
+uchger-cur_limit.cdp_cur_limit,
+uchger-cur_limit.aca_cur_limit);
+}
+
+static ssize_t cur_limit_store(struct device *dev,
+  struct device_attribute *attr,
+  const char *buf, size_t count)
+{
+   struct usb_charger *uchger = dev_to_uchger(dev);
+   struct usb_charger_cur_limit cur;
+   int ret;
+
+   ret = sscanf(buf, %d %d %d %d,
+cur.sdp_cur_limit, cur.dcp_cur_limit,
+cur.cdp_cur_limit, cur.aca_cur_limit);
+   if (ret == 0)
+   return -EINVAL;
+
+   ret = usb_charger_set_cur_limit(uchger, cur);
+   if (ret  0)
+   return ret;
+
+   return count;
+}
+static DEVICE_ATTR_RW(cur_limit);
+
+static struct attribute *usb_charger_attrs[] = {
+   dev_attr_cur_limit.attr,
+   NULL
+};