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

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.

Providing a standard framework for doing this in the kernel.

Hi Baolin,

Quoted 6 lines · Baolin Wang

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.

Quoted 2 lines

Providing a standard framework for doing this in the kernel.

Why not add power supply class support into this?

Li Jun

Quoted 12 lines · Li Jun

Hi Baolin,

Quoted 8 lines · Baolin Wang

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.

Providing a standard framework for doing this in the kernel.

Quoted 2 lines

Why not add power supply class support into this?

Hi Jun,

We don't need the power supply class support into the usb charger,

just introduce the notify mechanism for power to set the current limit when notifying some events from usb charger. Maybe I misunderstand your meanings, please describe it detailedly. Thanks for your comments.

Quoted 2 lines

Li Jun

Signature · 2 lines

Baolin.wang
Best Regards

Quoted 16 lines · Baolin Wang

Quoted 14 lines · Li Jun

Hi Baolin,

Quoted 8 lines · Baolin Wang

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.

Providing a standard framework for doing this in the kernel.

Why not add power supply class support into this?

Quoted 3 lines

Hi Jun,

We don't need the power supply class support into the usb charger,

I suppose usb charger is also a power supply for the system, we can use power supply class framework for notify mechanism and get/set many attributes(maybe also the current limit), I see those usb charger drivers under ./driver/power/ are designed with power supply supported.

Li Jun

Quoted 13 lines

just introduce the notify mechanism for power to set the current limit when notifying some events from usb charger. Maybe I misunderstand your meanings, please describe it detailedly. Thanks for your comments.

Quoted 2 lines

Li Jun

--
Baolin.wang
Best Regards

Quoted 17 lines · Li Jun

Quoted 16 lines · Baolin Wang

Quoted 14 lines · Li Jun

Hi Baolin,

Quoted 8 lines · Baolin Wang

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.

Providing a standard framework for doing this in the kernel.

Why not add power supply class support into this?

Quoted 8 lines

Quoted 3 lines

Hi Jun,

We don't need the power supply class support into the usb charger,

I suppose usb charger is also a power supply for the system, we can use power supply class framework for notify mechanism and get/set many attributes(maybe also the current limit), I see those usb charger drivers under ./driver/power/ are designed with power supply supported.

I don't think so. The usb charger is rely on the usb gadget, which is not a complete power supply device and it combines the usb and the power supply. Thus we make it into usb gadget system. Thanks.

Quoted 6 lines

Li Jun

Quoted 5 lines

just introduce the notify mechanism for power to set the current limit when notifying some events from usb charger. Maybe I misunderstand your meanings, please describe it detailedly. Thanks for your comments.

Quoted 8 lines

Quoted 8 lines

Quoted 2 lines

Li Jun

--
Baolin.wang
Best Regards

Signature · 2 lines

Baolin.wang
Best Regards

Quoted 27 lines · Baolin Wang

Quoted 17 lines · Li Jun

Quoted 16 lines · Baolin Wang

Quoted 14 lines · Li Jun

Hi Baolin,

Quoted 8 lines · Baolin Wang

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.

Providing a standard framework for doing this in the kernel.

Why not add power supply class support into this?

Quoted 8 lines

Quoted 3 lines

Hi Jun,

We don't need the power supply class support into the usb charger,

I suppose usb charger is also a power supply for the system, we can use power supply class framework for notify mechanism and get/set many attributes(maybe also the current limit), I see those usb charger drivers under ./driver/power/ are designed with power supply supported.

Quoted 4 lines

I don't think so. The usb charger is rely on the usb gadget, which is not a complete power supply device and it combines the usb and the power supply. Thus we make it into usb gadget system. Thanks.

Why it cannot be a complete power supply device? I was thinking this framework can cover it, I have no doubt on putting this framework into gadget system, but still can't understand why we don't need power supply class at all for a usb charger, or you think introduce power supply into usb gadget is not a right direction from code structure point view?

Li Jun

Quoted 20 lines

Quoted 14 lines

Li Jun

Quoted 13 lines

just introduce the notify mechanism for power to set the current limit when notifying some events from usb charger. Maybe I misunderstand your meanings, please describe it detailedly. Thanks for your comments.

Quoted 2 lines

Li Jun

--
Baolin.wang
Best Regards

--
Baolin.wang
Best Regards

The usb charger framework is based on usb gadget, and each usb gadget can be one usb charger to set the current limitation.

This patch adds a notifier mechanism for usb charger to report to usb charger when the usb gadget state is changed.

Also we introduce a callback 'get_charger_type' which will implemented by user for usb gadget operations to get the usb charger type.

Signed-off-by Baolin Wang <[email protected]>

---
 drivers/usb/gadget/udc/udc-core.c |   38 +++++++++++++++++++++++++++++++++++++
 include/linux/usb/gadget.h        |   20 +++++++++++++++++++
 2 files changed, 58 insertions(+)

drivers/usb/gadget/udc/udc-core.c +33 -0

index f660afb..47b231c 100644
@@ -28,6 +28,7 @@
 #include <linux/usb/ch9.h>
 #include <linux/usb/gadget.h>
 #include <linux/usb.h>
+#include <linux/usb/usb_charger.h>
 
 /**
  * struct usb_udc - describes one usb device controller

@@ -129,6 +130,32 @@ void usb_gadget_giveback_request(struct usb_ep *ep,
 }
 EXPORT_SYMBOL_GPL(usb_gadget_giveback_request);
 
+int usb_gadget_register_notify(struct usb_gadget *gadget,
+			       struct notifier_block *nb)
+{
+	int ret;
+
+	mutex_lock(&gadget->lock);
+	ret = raw_notifier_chain_register(&gadget->nh, nb);
+	mutex_unlock(&gadget->lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(usb_gadget_register_notify);
+
+int usb_gadget_unregister_notify(struct usb_gadget *gadget,
+				 struct notifier_block *nb)
+{
+	int ret;
+
+	mutex_lock(&gadget->lock);
+	ret = raw_notifier_chain_unregister(&gadget->nh, nb);
+	mutex_unlock(&gadget->lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(usb_gadget_unregister_notify);
+
 /* ------------------------------------------------------------------------- */
 
 /**

@@ -226,6 +253,10 @@ static void usb_gadget_state_work(struct work_struct *work)
 	struct usb_gadget *gadget = work_to_gadget(work);
 	struct usb_udc *udc = gadget->udc;
 
+	mutex_lock(&gadget->lock);
+	raw_notifier_call_chain(&gadget->nh, gadget->state, gadget);
+	mutex_unlock(&gadget->lock);
+
 	if (udc)
 		sysfs_notify(&udc->dev.kobj, NULL, "state");
 }

@@ -364,6 +395,8 @@ int usb_add_gadget_udc_release(struct device *parent, struct usb_gadget *gadget,
 
 	dev_set_name(&gadget->dev, "gadget");
 	INIT_WORK(&gadget->work, usb_gadget_state_work);
+	RAW_INIT_NOTIFIER_HEAD(&gadget->nh);
+	mutex_init(&gadget->lock);
 	gadget->dev.parent = parent;
 
 #ifdef	CONFIG_HAS_DMA

drivers/usb/gadget/udc/udc-core.c +1 -0

 	return 0;
 
 err4:

@@ -481,6 +518,7 @@ void usb_del_gadget_udc(struct usb_gadget *gadget)
 	kobject_uevent(&udc->dev.kobj, KOBJ_REMOVE);
 	flush_work(&gadget->work);
 	device_unregister(&udc->dev);
+	usb_charger_exit(gadget);
 	device_unregister(&gadget->dev);
 }
 EXPORT_SYMBOL_GPL(usb_del_gadget_udc);

include/linux/usb/gadget.h +20 -0

index c14a69b..78cc862 100644
@@ -537,6 +537,7 @@ struct usb_gadget_ops {
 	struct usb_ep *(*match_ep)(struct usb_gadget *,
 			struct usb_endpoint_descriptor *,
 			struct usb_ss_ep_comp_descriptor *);
+	enum usb_charger_type	(*get_charger_type)(struct usb_gadget *);
 };
 
 /**

@@ -609,6 +610,9 @@ struct usb_gadget {
 	unsigned			out_epnum;
 	unsigned			in_epnum;
 	struct usb_otg_caps		*otg_caps;
+	struct raw_notifier_head	nh;
+	struct usb_charger		*uchger;
+	struct mutex			lock;
 
 	unsigned			sg_supported:1;
 	unsigned			is_otg:1;

@@ -1183,6 +1187,22 @@ extern void usb_gadget_unmap_request(struct usb_gadget *gadget,
 
 /*-------------------------------------------------------------------------*/
 
+/**
+ * Register a notifiee to get notified by any attach status changes from
+ * the usb gadget
+ */
+int usb_gadget_register_notify(struct usb_gadget *gadget,
+			       struct notifier_block *nb);
+
+/*-------------------------------------------------------------------------*/
+
+
+/* Unregister a notifiee from the usb gadget */
+int usb_gadget_unregister_notify(struct usb_gadget *gadget,
+				 struct notifier_block *nb);
+
+/*-------------------------------------------------------------------------*/
+
 /* utility to set gadget state properly */
 
 extern void usb_gadget_set_state(struct usb_gadget *gadget,

Signature · 1 line

1.7.9.5

Quoted 84 lines · Baolin Wang

The usb charger framework is based on usb gadget, and each usb gadget can be one usb charger to set the current limitation.

This patch adds a notifier mechanism for usb charger to report to usb charger when the usb gadget state is changed.

Also we introduce a callback 'get_charger_type' which will implemented by user for usb gadget operations to get the usb charger type.

Signed-off-by Baolin Wang <[email protected]>

---
 drivers/usb/gadget/udc/udc-core.c |   38 +++++++++++++++++++++++++++++++++++++
 include/linux/usb/gadget.h        |   20 +++++++++++++++++++
 2 files changed, 58 insertions(+)

drivers/usb/gadget/udc/udc-core.c +33 -0

index f660afb..47b231c 100644
@@ -28,6 +28,7 @@
 #include <linux/usb/ch9.h>
 #include <linux/usb/gadget.h>
 #include <linux/usb.h>
+#include <linux/usb/usb_charger.h>
 
 /**
  * struct usb_udc - describes one usb device controller

@@ -129,6 +130,32 @@ void usb_gadget_giveback_request(struct usb_ep *ep,
 }
 EXPORT_SYMBOL_GPL(usb_gadget_giveback_request);
 
+int usb_gadget_register_notify(struct usb_gadget *gadget,
+                            struct notifier_block *nb)
+{
+     int ret;
+
+     mutex_lock(&gadget->lock);
+     ret = raw_notifier_chain_register(&gadget->nh, nb);
+     mutex_unlock(&gadget->lock);
+
+     return ret;
+}
+EXPORT_SYMBOL_GPL(usb_gadget_register_notify);
+
+int usb_gadget_unregister_notify(struct usb_gadget *gadget,
+                              struct notifier_block *nb)
+{
+     int ret;
+
+     mutex_lock(&gadget->lock);
+     ret = raw_notifier_chain_unregister(&gadget->nh, nb);
+     mutex_unlock(&gadget->lock);
+
+     return ret;
+}
+EXPORT_SYMBOL_GPL(usb_gadget_unregister_notify);
+
 /* ------------------------------------------------------------------------- */
 
 /**

@@ -226,6 +253,10 @@ static void usb_gadget_state_work(struct work_struct *work)
      struct usb_gadget *gadget = work_to_gadget(work);
      struct usb_udc *udc = gadget->udc;
 
+     mutex_lock(&gadget->lock);
+     raw_notifier_call_chain(&gadget->nh, gadget->state, gadget);
+     mutex_unlock(&gadget->lock);
+
      if (udc)
              sysfs_notify(&udc->dev.kobj, NULL, "state");
 }

@@ -364,6 +395,8 @@ int usb_add_gadget_udc_release(struct device *parent, struct usb_gadget *gadget,
 
      dev_set_name(&gadget->dev, "gadget");
      INIT_WORK(&gadget->work, usb_gadget_state_work);
+     RAW_INIT_NOTIFIER_HEAD(&gadget->nh);
+     mutex_init(&gadget->lock);
      gadget->dev.parent = parent;
 
 #ifdef       CONFIG_HAS_DMA

@@ -405,6 +438,10 @@ int usb_add_gadget_udc_release(struct device *parent, struct usb_gadget *gadget,
 
      mutex_unlock(&udc_lock);
 

drivers/usb/gadget/udc/udc-core.c int usb_add_gadget_udc_release(struct device *parent, struct usb_gadget *gadget, · line 444

Quoted 4 lines

drivers/usb/gadget/udc/udc-core.c +4 -0

+     ret = usb_charger_init(gadget);
+     if (ret)
+             goto err4;
+

If the charger's initialization fails, you may need to call device_del(&udc->dev).

Peter

Quoted 57 lines

drivers/usb/gadget/udc/udc-core.c +1 -0

      return 0;
 
 err4:

@@ -481,6 +518,7 @@ void usb_del_gadget_udc(struct usb_gadget *gadget)
      kobject_uevent(&udc->dev.kobj, KOBJ_REMOVE);
      flush_work(&gadget->work);
      device_unregister(&udc->dev);
+     usb_charger_exit(gadget);
      device_unregister(&gadget->dev);
 }
 EXPORT_SYMBOL_GPL(usb_del_gadget_udc);

include/linux/usb/gadget.h +20 -1

index c14a69b..78cc862 100644
@@ -537,6 +537,7 @@ struct usb_gadget_ops {
      struct usb_ep *(*match_ep)(struct usb_gadget *,
                      struct usb_endpoint_descriptor *,
                      struct usb_ss_ep_comp_descriptor *);
+     enum usb_charger_type   (*get_charger_type)(struct usb_gadget *);
 };
 
 /**

@@ -609,6 +610,9 @@ struct usb_gadget {
      unsigned                        out_epnum;
      unsigned                        in_epnum;
      struct usb_otg_caps             *otg_caps;
+     struct raw_notifier_head        nh;
+     struct usb_charger              *uchger;
+     struct mutex                    lock;
 
      unsigned                        sg_supported:1;
      unsigned                        is_otg:1;

@@ -1183,6 +1187,22 @@ extern void usb_gadget_unmap_request(struct usb_gadget *gadget,
 
 /*-------------------------------------------------------------------------*/
 
+/**
+ * Register a notifiee to get notified by any attach status changes from
+ * the usb gadget
+ */
+int usb_gadget_register_notify(struct usb_gadget *gadget,
+                            struct notifier_block *nb);
+
+/*-------------------------------------------------------------------------*/
+
+
+/* Unregister a notifiee from the usb gadget */
+int usb_gadget_unregister_notify(struct usb_gadget *gadget,
+                              struct notifier_block *nb);
+
+/*-------------------------------------------------------------------------*/
+
 /* utility to set gadget state properly */
 
 extern void usb_gadget_set_state(struct usb_gadget *gadget,
--

Quoted 2 lines

1.7.9.5

--

Best Regards,
Peter Chen

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 <[email protected]>

---
 drivers/usb/gadget/Kconfig      |    7 +
 drivers/usb/gadget/Makefile     |    1 +
 drivers/usb/gadget/charger.c    |  561 +++++++++++++++++++++++++++++++++++++++
 include/linux/usb/usb_charger.h |  145 ++++++++++
 4 files changed, 714 insertions(+)
 create mode 100644 drivers/usb/gadget/charger.c
 create mode 100644 include/linux/usb/usb_charger.h

drivers/usb/gadget/Kconfig +7 -0

index bcf83c0..3d2b959 100644
@@ -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"
 
 #

drivers/usb/gadget/Makefile +1 -0

index 598a67d..1e421c1 100644
@@ -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

drivers/usb/gadget/charger.c new file +0 -0

new file mode 100644
index 0000000..f24f7b7

drivers/usb/gadget/charger.c new file +59 -0

+ */
+
+#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 usb_charger_cur_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 usb_charger_cur_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);

drivers/usb/gadget/charger.c new file +334 -0

+
+/*
+ * 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 usb_charger_put().
+ */
+struct usb_charger *usb_charger_find_by_name(const char *name)
+{
+	struct device *udev;
+
+	if (!name)
+		return ERR_PTR(-EINVAL);
+
+	udev = bus_find_device_by_name(&usb_charger_subsys, NULL, name);
+	if (!udev)
+		return ERR_PTR(-ENODEV);
+
+	return dev_to_uchger(udev);
+}
+
+/*
+ * usb_charger_get() - Reference a usb charger.
+ * @uchger - usb charger
+ */
+struct usb_charger *usb_charger_get(struct usb_charger *uchger)
+{
+	return (uchger && get_device(&uchger->dev)) ? uchger : NULL;
+}
+
+/*
+ * usb_charger_put() - Dereference a usb charger.
+ * @uchger - charger to release
+ */
+void usb_charger_put(struct usb_charger *uchger)
+{
+	if (uchger)
+		put_device(&uchger->dev);
+}
+
+/*
+ * usb_charger_register_notify() - Register a notifiee to get notified by
+ * any attach status changes from the usb charger detection.
+ * @uchger - the usb charger device which is monitored.
+ * @nb - a notifier block to be registered.
+ */
+int usb_charger_register_notify(struct usb_charger *uchger,
+				struct notifier_block *nb)
+{
+	int ret;
+
+	if (!uchger || !nb)
+		return -EINVAL;
+
+	mutex_lock(&uchger->lock);
+	ret = raw_notifier_chain_register(&uchger->uchger_nh, nb);
+
+	/* Generate an initial notify so users start in the right state */
+	if (!ret) {
+		usb_charger_detect_type(uchger);
+		raw_notifier_call_chain(&uchger->uchger_nh,
+					usb_charger_get_cur_limit(uchger),
+					uchger);
+	}
+	mutex_unlock(&uchger->lock);
+
+	return ret;
+}
+
+/*
+ * usb_charger_unregister_notify() - Unregister a notifiee from the usb charger.
+ * @uchger - the usb charger device which is monitored.
+ * @nb - a notifier block to be unregistered.
+ */
+int usb_charger_unregister_notify(struct usb_charger *uchger,
+				  struct notifier_block *nb)
+{
+	int ret;
+
+	if (!uchger || !nb)
+		return -EINVAL;
+
+	mutex_lock(&uchger->lock);
+	ret = raw_notifier_chain_unregister(&uchger->uchger_nh, nb);
+	mutex_unlock(&uchger->lock);
+
+	return ret;
+}
+
+/*
+ * usb_charger_detect_type() - Get the usb charger type by the callback
+ * which is implemented by gadget operations.
+ * @uchger - the usb charger device.
+ *
+ * return the usb charger type.
+ */
+enum usb_charger_type
+usb_charger_detect_type(struct usb_charger *uchger)
+{
+	if (uchger->gadget && uchger->gadget->ops
+	    && uchger->gadget->ops->get_charger_type)
+		uchger->type =
+			uchger->gadget->ops->get_charger_type(uchger->gadget);
+	else
+		uchger->type = UNKNOWN_TYPE;
+
+	return uchger->type;
+}
+
+/*
+ * usb_charger_set_cur_limit() - Set the current limitation.
+ * @uchger - the usb charger device.
+ * @cur_limit_set - the current limitation.
+ */
+int usb_charger_set_cur_limit(struct usb_charger *uchger,
+			      struct usb_charger_cur_limit *cur_limit_set)
+{
+	if (!uchger || !cur_limit_set)
+		return -EINVAL;
+
+	uchger->cur_limit.sdp_cur_limit = cur_limit_set->sdp_cur_limit;
+	uchger->cur_limit.dcp_cur_limit = cur_limit_set->dcp_cur_limit;
+	uchger->cur_limit.cdp_cur_limit = cur_limit_set->cdp_cur_limit;
+	uchger->cur_limit.aca_cur_limit = cur_limit_set->aca_cur_limit;
+	return 0;
+}
+
+/*
+ * usb_charger_get_cur_limit() - Get the current limitation by
+ * different usb charger type.
+ * @uchger - the usb charger device.
+ *
+ * return the current limitation to set.
+ */
+unsigned int
+usb_charger_get_cur_limit(struct usb_charger *uchger)
+{
+	enum usb_charger_type uchger_type = uchger->type;
+	unsigned int cur_limit;
+
+	switch (uchger_type) {
+	case SDP_TYPE:
+		cur_limit = uchger->cur_limit.sdp_cur_limit;
+		break;
+	case DCP_TYPE:
+		cur_limit = uchger->cur_limit.dcp_cur_limit;
+		break;
+	case CDP_TYPE:
+		cur_limit = uchger->cur_limit.cdp_cur_limit;
+		break;
+	case ACA_TYPE:
+		cur_limit = uchger->cur_limit.aca_cur_limit;
+		break;
+	default:
+		return 0;
+	}
+
+	return cur_limit;
+}
+
+/*
+ * usb_charger_notifier_others() - It will notify other device registered
+ * on usb charger when the usb charger state is changed.
+ * @uchger - the usb charger device.
+ * @state - the state of the usb charger.
+ */
+static void
+usb_charger_notify_others(struct usb_charger *uchger,
+			  enum usb_charger_state state)
+{
+	mutex_lock(&uchger->lock);
+	uchger->state = state;
+
+	switch (state) {
+	case USB_CHARGER_PRESENT:
+		usb_charger_detect_type(uchger);
+		raw_notifier_call_chain(&uchger->uchger_nh,
+			usb_charger_get_cur_limit(uchger),
+			uchger);
+		break;
+	case USB_CHARGER_REMOVE:
+		uchger->type = UNKNOWN_TYPE;
+		raw_notifier_call_chain(&uchger->uchger_nh, 0, uchger);
+		break;
+	default:
+		dev_warn(&uchger->dev, "Unknown USB charger state: %d\n",
+			 state);
+		break;
+	}
+	mutex_unlock(&uchger->lock);
+}
+
+/*
+ * usb_charger_plug_by_extcon() - The notifier call function which is registered
+ * on the extcon device.
+ * @nb - the notifier block that notified by extcon device.
+ * @state - the extcon device state.
+ * @data - here specify a extcon device.
+ *
+ * return the notify flag.
+ */
+static int
+usb_charger_plug_by_extcon(struct notifier_block *nb,
+			   unsigned long state, void *data)
+{
+	struct usb_charger_nb *extcon_nb =
+		container_of(nb, struct usb_charger_nb, nb);
+	struct usb_charger *uchger = extcon_nb->uchger;
+	enum usb_charger_state uchger_state;
+
+	if (!uchger)
+		return NOTIFY_BAD;
+
+	/* Report event to power to setting the current limitation
+	 * for this usb charger when one usb charger is added or removed
+	 * with detecting by extcon device.
+	 */
+	if (state)
+		uchger_state = USB_CHARGER_PRESENT;
+	else
+		uchger_state = USB_CHARGER_REMOVE;
+
+	usb_charger_notify_others(uchger, uchger_state);
+
+	return NOTIFY_OK;
+}
+
+/*
+ * usb_charger_plug_by_gadget() - Set the usb charger current limitation
+ * according to the usb gadget device state.
+ * @nb - the notifier block that notified by usb gadget device.
+ * @state - the usb gadget state.
+ * @data - here specify a usb gadget device.
+ */
+static int
+usb_charger_plug_by_gadget(struct notifier_block *nb,
+			   unsigned long state, void *data)
+{
+	struct usb_gadget *gadget = (struct usb_gadget *)data;
+	struct usb_charger *uchger = gadget->uchger;
+	enum usb_charger_state uchger_state;
+
+	if (!uchger)
+		return NOTIFY_BAD;
+
+	/* Report event to power to setting the current limitation
+	 * for this usb charger when one usb charger state is changed
+	 * with detecting by usb gadget state.
+	 */
+	if (uchger->old_gadget_state != state) {
+		uchger->old_gadget_state = state;
+
+		if (state >= USB_STATE_ATTACHED)
+			uchger_state = USB_CHARGER_PRESENT;
+		else if (state == USB_STATE_NOTATTACHED)
+			uchger_state = USB_CHARGER_REMOVE;
+		else
+			uchger_state = USB_CHARGER_DEFAULT;
+
+		usb_charger_notify_others(uchger, uchger_state);
+	}
+
+	return NOTIFY_OK;
+}
+
+static int devm_uchger_dev_match(struct device *dev, void *res, void *data)
+{
+	struct usb_charger **r = res;
+
+	if (WARN_ON(!r || !*r))
+		return 0;
+
+	return *r == data;
+}
+
+static void usb_charger_release(struct device *dev)
+{
+	struct usb_charger *uchger = dev_get_drvdata(dev);
+
+	kfree(uchger->name);
+	kfree(uchger);
+}
+
+/*
+ * usb_charger_unregister() - Unregister a usb charger device.
+ * @uchger - the usb charger to be unregistered.
+ */
+static int usb_charger_unregister(struct usb_charger *uchger)
+{
+	if (!uchger)
+		return -EINVAL;
+
+	sysfs_remove_group(&uchger->dev.kobj, &uchger_attr_group);
+	device_unregister(&uchger->dev);
+
+	return 0;
+}
+
+static void devm_uchger_dev_unreg(struct device *dev, void *res)
+{
+	usb_charger_unregister(*(struct usb_charger **)res);
+}
+
+void devm_usb_charger_unregister(struct device *dev,
+				 struct usb_charger *uchger)
+{
+	devres_release(dev, devm_uchger_dev_unreg,
+		       devm_uchger_dev_match, uchger);
+}
+
+/*
+ * usb_charger_register() - Register a new usb charger device
+ * which is created by the usb charger framework.
+ * @uchger - the new usb charger device.
+ */
+static int usb_charger_register(struct device *dev, struct usb_charger *uchger)
+{
+	int ret;
+
+	if (!uchger) {
+		dev_err(dev, "no device provided for charger\n");
+		return -EINVAL;
+	}
+
+	uchger->dev.parent = dev;
+	uchger->dev.release = usb_charger_release;
+	uchger->dev.bus = &usb_charger_subsys;
+
+	ret = ida_simple_get(&usb_charger_ida, 0, 0, GFP_KERNEL);
+	if (ret < 0) {
+		dev_err(dev, "get usb charger id failed\n");
+		return ret;
+	}

drivers/usb/gadget/charger.c new file +33 -0

+	if (ret)
+		goto fail_create_files;
+
+	return 0;
+
+fail_create_files:
+	device_unregister(&uchger->dev);
+fail_register:
+	put_device(&uchger->dev);
+	ida_simple_remove(&usb_charger_ida, uchger->id);
+	uchger->id = -1;
+	dev_err(dev, "Failed to register usb charger (%s)\n",
+		uchger->name);
+	return ret;
+}
+
+int devm_usb_charger_register(struct device *dev,
+			      struct usb_charger *uchger)
+{
+	struct usb_charger **ptr;
+	int ret;
+
+	ptr = devres_alloc(devm_uchger_dev_unreg, sizeof(*ptr), GFP_KERNEL);
+	if (!ptr)
+		return -ENOMEM;
+
+	ret = usb_charger_register(dev, uchger);
+	if (ret) {
+		devres_free(ptr);
+		return ret;
+	}
+
+	*ptr = uchger;

drivers/usb/gadget/charger.c new file +75 -0

+	if (!str)
+		return -ENOMEM;
+
+	strcpy(str, buf);
+	uchger->name = str;
+	uchger->type = UNKNOWN_TYPE;
+	uchger->state = USB_CHARGER_DEFAULT;
+	uchger->id = -1;
+	uchger->cur_limit.sdp_cur_limit = DEFAULT_SDP_CUR_LIMIT;
+	uchger->cur_limit.dcp_cur_limit = DEFAULT_DCP_CUR_LIMIT;
+	uchger->cur_limit.cdp_cur_limit = DEFAULT_CDP_CUR_LIMIT;
+	uchger->cur_limit.aca_cur_limit = DEFAULT_ACA_CUR_LIMIT;
+
+	mutex_init(&uchger->lock);
+	INIT_LIST_HEAD(&uchger->entry);
+	RAW_INIT_NOTIFIER_HEAD(&uchger->uchger_nh);
+
+	/* register a notifier on a extcon device if it is exsited */
+	edev = extcon_get_edev_by_phandle(ugadget->dev.parent, 0);
+	if (!IS_ERR_OR_NULL(edev)) {
+		uchger->extcon_dev = edev;
+		uchger->extcon_nb.nb.notifier_call = usb_charger_plug_by_extcon;
+		uchger->extcon_nb.uchger = uchger;
+		extcon_register_notifier(edev, EXTCON_USB, &uchger->extcon_nb.nb);
+	}
+
+	/* register a notifier on a usb gadget device */
+	uchger->gadget = ugadget;
+	ugadget->uchger = uchger;
+	uchger->old_gadget_state = ugadget->state;
+	uchger->gadget_nb.notifier_call = usb_charger_plug_by_gadget;
+	usb_gadget_register_notify(ugadget, &uchger->gadget_nb);
+
+	/* register a new usb charger */
+	ret = usb_charger_register(&ugadget->dev, uchger);
+	if (ret)
+		goto fail;
+
+	return 0;
+
+fail:
+	if (uchger->extcon_dev)
+		extcon_unregister_notifier(uchger->extcon_dev,
+					   EXTCON_USB, &uchger->extcon_nb.nb);
+
+	usb_gadget_unregister_notify(uchger->gadget, &uchger->gadget_nb);
+	return ret;
+}
+
+int usb_charger_exit(struct usb_gadget *ugadget)
+{
+	struct usb_charger *uchger = ugadget->uchger;
+
+	if (!uchger)
+		return -EINVAL;
+
+	if (uchger->extcon_dev)
+		extcon_unregister_notifier(uchger->extcon_dev,
+					   EXTCON_USB, &uchger->extcon_nb.nb);
+
+	usb_gadget_unregister_notify(uchger->gadget, &uchger->gadget_nb);
+	ida_simple_remove(&usb_charger_ida, uchger->id);
+
+	return usb_charger_unregister(uchger);
+}
+
+static int __init usb_charger_sysfs_init(void)
+{
+	return subsys_system_register(&usb_charger_subsys, NULL);
+}
+core_initcall(usb_charger_sysfs_init);
+
+MODULE_AUTHOR("Baolin Wang <[email protected]>");
+MODULE_DESCRIPTION("USB charger driver");
+MODULE_LICENSE("GPL");

include/linux/usb/usb_charger.h new file +34 -0

new file mode 100644
index 0000000..8cbfaae
@@ -0,0 +1,145 @@
+#ifndef __LINUX_USB_CHARGER_H__
+#define __LINUX_USB_CHARGER_H__
+
+#include <linux/device.h>
+#include <linux/notifier.h>
+#include <linux/sysfs.h>
+#include <linux/usb/ch9.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,
+};
+
+/* Current limitation by charger type */
+struct usb_charger_cur_limit {
+	unsigned int sdp_cur_limit;
+	unsigned int dcp_cur_limit;
+	unsigned int cdp_cur_limit;

Quoted 52 lines · 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 <[email protected]>

---
 drivers/usb/gadget/Kconfig      |    7 +
 drivers/usb/gadget/Makefile     |    1 +
 drivers/usb/gadget/charger.c    |  561 +++++++++++++++++++++++++++++++++++++++
 include/linux/usb/usb_charger.h |  145 ++++++++++
 4 files changed, 714 insertions(+)
 create mode 100644 drivers/usb/gadget/charger.c
 create mode 100644 include/linux/usb/usb_charger.h

drivers/usb/gadget/Kconfig +7 -0

index bcf83c0..3d2b959 100644
@@ -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"
 
 #

drivers/usb/gadget/Makefile +0 -0

index 598a67d..1e421c1 100644
@@ -10,3 +10,4 @@ libcomposite-y                      := usbstring.o config.o epautoconf.o
 libcomposite-y                       += composite.o functions.o configfs.o u_f.o
 

drivers/usb/gadget/charger.c line 2

Quoted 10 lines

drivers/usb/gadget/Makefile +1 -0

 obj-$(CONFIG_USB_GADGET)     += udc/ function/ legacy/
+obj-$(CONFIG_USB_CHARGER)    += charger.o

drivers/usb/gadget/charger.c new file +2 -0

new file mode 100644
index 0000000..f24f7b7
@@ -0,0 +1,561 @@
+/*
+ * usb charger.c -- USB charger driver

I think your company also wants a copyright line here. Not that it means anything at all, but some lawyers love cargo-cult text blobs.

drivers/usb/gadget/charger.c line 7

Quoted 6 lines

drivers/usb/gadget/charger.c new file +5 -0

+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.

I have to ask, do you really mean "any later version"?

Quoted 63 lines

drivers/usb/gadget/charger.c new file +63 -0

+ */
+
+#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 usb_charger_cur_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 usb_charger_cur_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);

drivers/usb/gadget/charger.c line 76

Quoted 6 lines

drivers/usb/gadget/charger.c new file +6 -0

+     if (ret < 0)
+             return ret;
+
+     return count;
+}
+static DEVICE_ATTR(cur_limit, 0644, usb_charger_cur_show, usb_charger_cur_store);

DEVICE_ATTR_RW()?

drivers/usb/gadget/charger.c line 85

Quoted 9 lines

drivers/usb/gadget/charger.c new file +9 -0

+
+static struct attribute *uchger_attributes[] = {
+     &dev_attr_cur_limit.attr,
+     NULL
+};
+
+static const struct attribute_group uchger_attr_group = {
+     .attrs = uchger_attributes,
+};

ATTRIBUTE_GROUPS()?

Quoted 334 lines

drivers/usb/gadget/charger.c new file +334 -0

+
+/*
+ * 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 usb_charger_put().
+ */
+struct usb_charger *usb_charger_find_by_name(const char *name)
+{
+     struct device *udev;
+
+     if (!name)
+             return ERR_PTR(-EINVAL);
+
+     udev = bus_find_device_by_name(&usb_charger_subsys, NULL, name);
+     if (!udev)
+             return ERR_PTR(-ENODEV);
+
+     return dev_to_uchger(udev);
+}
+
+/*
+ * usb_charger_get() - Reference a usb charger.
+ * @uchger - usb charger
+ */
+struct usb_charger *usb_charger_get(struct usb_charger *uchger)
+{
+     return (uchger && get_device(&uchger->dev)) ? uchger : NULL;
+}
+
+/*
+ * usb_charger_put() - Dereference a usb charger.
+ * @uchger - charger to release
+ */
+void usb_charger_put(struct usb_charger *uchger)
+{
+     if (uchger)
+             put_device(&uchger->dev);
+}
+
+/*
+ * usb_charger_register_notify() - Register a notifiee to get notified by
+ * any attach status changes from the usb charger detection.
+ * @uchger - the usb charger device which is monitored.
+ * @nb - a notifier block to be registered.
+ */
+int usb_charger_register_notify(struct usb_charger *uchger,
+                             struct notifier_block *nb)
+{
+     int ret;
+
+     if (!uchger || !nb)
+             return -EINVAL;
+
+     mutex_lock(&uchger->lock);
+     ret = raw_notifier_chain_register(&uchger->uchger_nh, nb);
+
+     /* Generate an initial notify so users start in the right state */
+     if (!ret) {
+             usb_charger_detect_type(uchger);
+             raw_notifier_call_chain(&uchger->uchger_nh,
+                                     usb_charger_get_cur_limit(uchger),
+                                     uchger);
+     }
+     mutex_unlock(&uchger->lock);
+
+     return ret;
+}
+
+/*
+ * usb_charger_unregister_notify() - Unregister a notifiee from the usb charger.
+ * @uchger - the usb charger device which is monitored.
+ * @nb - a notifier block to be unregistered.
+ */
+int usb_charger_unregister_notify(struct usb_charger *uchger,
+                               struct notifier_block *nb)
+{
+     int ret;
+
+     if (!uchger || !nb)
+             return -EINVAL;
+
+     mutex_lock(&uchger->lock);
+     ret = raw_notifier_chain_unregister(&uchger->uchger_nh, nb);
+     mutex_unlock(&uchger->lock);
+
+     return ret;
+}
+
+/*
+ * usb_charger_detect_type() - Get the usb charger type by the callback
+ * which is implemented by gadget operations.
+ * @uchger - the usb charger device.
+ *
+ * return the usb charger type.
+ */
+enum usb_charger_type
+usb_charger_detect_type(struct usb_charger *uchger)
+{
+     if (uchger->gadget && uchger->gadget->ops
+         && uchger->gadget->ops->get_charger_type)
+             uchger->type =
+                     uchger->gadget->ops->get_charger_type(uchger->gadget);
+     else
+             uchger->type = UNKNOWN_TYPE;
+
+     return uchger->type;
+}
+
+/*
+ * usb_charger_set_cur_limit() - Set the current limitation.
+ * @uchger - the usb charger device.
+ * @cur_limit_set - the current limitation.
+ */
+int usb_charger_set_cur_limit(struct usb_charger *uchger,
+                           struct usb_charger_cur_limit *cur_limit_set)
+{
+     if (!uchger || !cur_limit_set)
+             return -EINVAL;
+
+     uchger->cur_limit.sdp_cur_limit = cur_limit_set->sdp_cur_limit;
+     uchger->cur_limit.dcp_cur_limit = cur_limit_set->dcp_cur_limit;
+     uchger->cur_limit.cdp_cur_limit = cur_limit_set->cdp_cur_limit;
+     uchger->cur_limit.aca_cur_limit = cur_limit_set->aca_cur_limit;
+     return 0;
+}
+
+/*
+ * usb_charger_get_cur_limit() - Get the current limitation by
+ * different usb charger type.
+ * @uchger - the usb charger device.
+ *
+ * return the current limitation to set.
+ */
+unsigned int
+usb_charger_get_cur_limit(struct usb_charger *uchger)
+{
+     enum usb_charger_type uchger_type = uchger->type;
+     unsigned int cur_limit;
+
+     switch (uchger_type) {
+     case SDP_TYPE:
+             cur_limit = uchger->cur_limit.sdp_cur_limit;
+             break;
+     case DCP_TYPE:
+             cur_limit = uchger->cur_limit.dcp_cur_limit;
+             break;
+     case CDP_TYPE:
+             cur_limit = uchger->cur_limit.cdp_cur_limit;
+             break;
+     case ACA_TYPE:
+             cur_limit = uchger->cur_limit.aca_cur_limit;
+             break;
+     default:
+             return 0;
+     }
+
+     return cur_limit;
+}
+
+/*
+ * usb_charger_notifier_others() - It will notify other device registered
+ * on usb charger when the usb charger state is changed.
+ * @uchger - the usb charger device.
+ * @state - the state of the usb charger.
+ */
+static void
+usb_charger_notify_others(struct usb_charger *uchger,
+                       enum usb_charger_state state)
+{
+     mutex_lock(&uchger->lock);
+     uchger->state = state;
+
+     switch (state) {
+     case USB_CHARGER_PRESENT:
+             usb_charger_detect_type(uchger);
+             raw_notifier_call_chain(&uchger->uchger_nh,
+                     usb_charger_get_cur_limit(uchger),
+                     uchger);
+             break;
+     case USB_CHARGER_REMOVE:
+             uchger->type = UNKNOWN_TYPE;
+             raw_notifier_call_chain(&uchger->uchger_nh, 0, uchger);
+             break;
+     default:
+             dev_warn(&uchger->dev, "Unknown USB charger state: %d\n",
+                      state);
+             break;
+     }
+     mutex_unlock(&uchger->lock);
+}
+
+/*
+ * usb_charger_plug_by_extcon() - The notifier call function which is registered
+ * on the extcon device.
+ * @nb - the notifier block that notified by extcon device.
+ * @state - the extcon device state.
+ * @data - here specify a extcon device.
+ *
+ * return the notify flag.
+ */
+static int
+usb_charger_plug_by_extcon(struct notifier_block *nb,
+                        unsigned long state, void *data)
+{
+     struct usb_charger_nb *extcon_nb =
+             container_of(nb, struct usb_charger_nb, nb);
+     struct usb_charger *uchger = extcon_nb->uchger;
+     enum usb_charger_state uchger_state;
+
+     if (!uchger)
+             return NOTIFY_BAD;
+
+     /* Report event to power to setting the current limitation
+      * for this usb charger when one usb charger is added or removed
+      * with detecting by extcon device.
+      */
+     if (state)
+             uchger_state = USB_CHARGER_PRESENT;
+     else
+             uchger_state = USB_CHARGER_REMOVE;
+
+     usb_charger_notify_others(uchger, uchger_state);
+
+     return NOTIFY_OK;
+}
+
+/*
+ * usb_charger_plug_by_gadget() - Set the usb charger current limitation
+ * according to the usb gadget device state.
+ * @nb - the notifier block that notified by usb gadget device.
+ * @state - the usb gadget state.
+ * @data - here specify a usb gadget device.
+ */
+static int
+usb_charger_plug_by_gadget(struct notifier_block *nb,
+                        unsigned long state, void *data)
+{
+     struct usb_gadget *gadget = (struct usb_gadget *)data;
+     struct usb_charger *uchger = gadget->uchger;
+     enum usb_charger_state uchger_state;
+
+     if (!uchger)
+             return NOTIFY_BAD;
+
+     /* Report event to power to setting the current limitation
+      * for this usb charger when one usb charger state is changed
+      * with detecting by usb gadget state.
+      */
+     if (uchger->old_gadget_state != state) {
+             uchger->old_gadget_state = state;
+
+             if (state >= USB_STATE_ATTACHED)
+                     uchger_state = USB_CHARGER_PRESENT;
+             else if (state == USB_STATE_NOTATTACHED)
+                     uchger_state = USB_CHARGER_REMOVE;
+             else
+                     uchger_state = USB_CHARGER_DEFAULT;
+
+             usb_charger_notify_others(uchger, uchger_state);
+     }
+
+     return NOTIFY_OK;
+}
+
+static int devm_uchger_dev_match(struct device *dev, void *res, void *data)
+{
+     struct usb_charger **r = res;
+
+     if (WARN_ON(!r || !*r))
+             return 0;
+
+     return *r == data;
+}
+
+static void usb_charger_release(struct device *dev)
+{
+     struct usb_charger *uchger = dev_get_drvdata(dev);
+
+     kfree(uchger->name);
+     kfree(uchger);
+}
+
+/*
+ * usb_charger_unregister() - Unregister a usb charger device.
+ * @uchger - the usb charger to be unregistered.
+ */
+static int usb_charger_unregister(struct usb_charger *uchger)
+{
+     if (!uchger)
+             return -EINVAL;
+
+     sysfs_remove_group(&uchger->dev.kobj, &uchger_attr_group);
+     device_unregister(&uchger->dev);
+
+     return 0;
+}
+
+static void devm_uchger_dev_unreg(struct device *dev, void *res)
+{
+     usb_charger_unregister(*(struct usb_charger **)res);
+}
+
+void devm_usb_charger_unregister(struct device *dev,
+                              struct usb_charger *uchger)
+{
+     devres_release(dev, devm_uchger_dev_unreg,
+                    devm_uchger_dev_match, uchger);
+}
+
+/*
+ * usb_charger_register() - Register a new usb charger device
+ * which is created by the usb charger framework.
+ * @uchger - the new usb charger device.
+ */
+static int usb_charger_register(struct device *dev, struct usb_charger *uchger)
+{
+     int ret;
+
+     if (!uchger) {
+             dev_err(dev, "no device provided for charger\n");
+             return -EINVAL;
+     }
+
+     uchger->dev.parent = dev;
+     uchger->dev.release = usb_charger_release;
+     uchger->dev.bus = &usb_charger_subsys;
+
+     ret = ida_simple_get(&usb_charger_ida, 0, 0, GFP_KERNEL);
+     if (ret < 0) {
+             dev_err(dev, "get usb charger id failed\n");
+             return ret;
+     }

drivers/usb/gadget/charger.c line 429

Quoted 10 lines

drivers/usb/gadget/charger.c new file +10 -0

+
+     uchger->id = ret;
+     dev_set_name(&uchger->dev, "usb-charger.%d", uchger->id);
+     dev_set_drvdata(&uchger->dev, uchger);
+
+     ret = device_register(&uchger->dev);
+     if (ret)
+             goto fail_register;
+
+     ret = sysfs_create_group(&uchger->dev.kobj, &uchger_attr_group);

And you just raced with userspace, and lost :(

Assign the group to the device _before_ you tell userspace about it.

The big hint here that is wrong is that you have to call a sysfs_* function for a struct device. There is no device_create_group() call for a reason.

Quoted 39 lines

drivers/usb/gadget/charger.c new file +37 -0

+     if (ret)
+             goto fail_create_files;
+
+     return 0;
+
+fail_create_files:
+     device_unregister(&uchger->dev);
+fail_register:
+     put_device(&uchger->dev);
+     ida_simple_remove(&usb_charger_ida, uchger->id);
+     uchger->id = -1;
+     dev_err(dev, "Failed to register usb charger (%s)\n",
+             uchger->name);
+     return ret;
+}
+
+int devm_usb_charger_register(struct device *dev,
+                           struct usb_charger *uchger)
+{
+     struct usb_charger **ptr;
+     int ret;
+
+     ptr = devres_alloc(devm_uchger_dev_unreg, sizeof(*ptr), GFP_KERNEL);
+     if (!ptr)
+             return -ENOMEM;
+
+     ret = usb_charger_register(dev, uchger);
+     if (ret) {
+             devres_free(ptr);
+             return ret;
+     }
+
+     *ptr = uchger;
+     devres_add(dev, ptr);
+
+     return 0;
+}

drivers/usb/gadget/charger.c line 472

Quoted 6 lines

drivers/usb/gadget/charger.c new file +6 -0

+
+int usb_charger_init(struct usb_gadget *ugadget)
+{
+     struct usb_charger *uchger;
+     struct extcon_dev *edev;
+     char buf[100];

That's a lot of stack, why?

Quoted 4 lines

drivers/usb/gadget/charger.c new file +4 -0

+     char *str;
+     int ret;
+
+     if (!ugadget)

drivers/usb/gadget/charger.c line 480

Quoted 4 lines

drivers/usb/gadget/charger.c new file +4 -0

+             return -EINVAL;
+
+     uchger = devm_kzalloc(&ugadget->dev, sizeof(struct usb_charger),
+                           GFP_KERNEL);

No, you are creating a new struct device, you can't assign its resources to another struct device, that breaks all of the lifetime rules. kzalloc() only please.

drivers/usb/gadget/charger.c line 486

Quoted 6 lines

drivers/usb/gadget/charger.c new file +6 -0

+     if (!uchger)
+             return -ENOMEM;
+
+     sprintf(buf, "usb-charger.%s", ugadget->name);
+     str = devm_kzalloc(&ugadget->dev, sizeof(char) * (strlen(buf) + 1),
+                        GFP_KERNEL);

Why have a string when you already have a name for the device, in the device itself? What is this all for?

Quoted 120 lines

drivers/usb/gadget/charger.c new file +75 -0

+     if (!str)
+             return -ENOMEM;
+
+     strcpy(str, buf);
+     uchger->name = str;
+     uchger->type = UNKNOWN_TYPE;
+     uchger->state = USB_CHARGER_DEFAULT;
+     uchger->id = -1;
+     uchger->cur_limit.sdp_cur_limit = DEFAULT_SDP_CUR_LIMIT;
+     uchger->cur_limit.dcp_cur_limit = DEFAULT_DCP_CUR_LIMIT;
+     uchger->cur_limit.cdp_cur_limit = DEFAULT_CDP_CUR_LIMIT;
+     uchger->cur_limit.aca_cur_limit = DEFAULT_ACA_CUR_LIMIT;
+
+     mutex_init(&uchger->lock);
+     INIT_LIST_HEAD(&uchger->entry);
+     RAW_INIT_NOTIFIER_HEAD(&uchger->uchger_nh);
+
+     /* register a notifier on a extcon device if it is exsited */
+     edev = extcon_get_edev_by_phandle(ugadget->dev.parent, 0);
+     if (!IS_ERR_OR_NULL(edev)) {
+             uchger->extcon_dev = edev;
+             uchger->extcon_nb.nb.notifier_call = usb_charger_plug_by_extcon;
+             uchger->extcon_nb.uchger = uchger;
+             extcon_register_notifier(edev, EXTCON_USB, &uchger->extcon_nb.nb);
+     }
+
+     /* register a notifier on a usb gadget device */
+     uchger->gadget = ugadget;
+     ugadget->uchger = uchger;
+     uchger->old_gadget_state = ugadget->state;
+     uchger->gadget_nb.notifier_call = usb_charger_plug_by_gadget;
+     usb_gadget_register_notify(ugadget, &uchger->gadget_nb);
+
+     /* register a new usb charger */
+     ret = usb_charger_register(&ugadget->dev, uchger);
+     if (ret)
+             goto fail;
+
+     return 0;
+
+fail:
+     if (uchger->extcon_dev)
+             extcon_unregister_notifier(uchger->extcon_dev,
+                                        EXTCON_USB, &uchger->extcon_nb.nb);
+
+     usb_gadget_unregister_notify(uchger->gadget, &uchger->gadget_nb);
+     return ret;
+}
+
+int usb_charger_exit(struct usb_gadget *ugadget)
+{
+     struct usb_charger *uchger = ugadget->uchger;
+
+     if (!uchger)
+             return -EINVAL;
+
+     if (uchger->extcon_dev)
+             extcon_unregister_notifier(uchger->extcon_dev,
+                                        EXTCON_USB, &uchger->extcon_nb.nb);
+
+     usb_gadget_unregister_notify(uchger->gadget, &uchger->gadget_nb);
+     ida_simple_remove(&usb_charger_ida, uchger->id);
+
+     return usb_charger_unregister(uchger);
+}
+
+static int __init usb_charger_sysfs_init(void)
+{
+     return subsys_system_register(&usb_charger_subsys, NULL);
+}
+core_initcall(usb_charger_sysfs_init);
+
+MODULE_AUTHOR("Baolin Wang <[email protected]>");
+MODULE_DESCRIPTION("USB charger driver");
+MODULE_LICENSE("GPL");

include/linux/usb/usb_charger.h new file +38 -0

new file mode 100644
index 0000000..8cbfaae
@@ -0,0 +1,145 @@
+#ifndef __LINUX_USB_CHARGER_H__
+#define __LINUX_USB_CHARGER_H__
+
+#include <linux/device.h>
+#include <linux/notifier.h>
+#include <linux/sysfs.h>
+#include <linux/usb/ch9.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,
+};
+
+/* Current limitation by charger type */
+struct usb_charger_cur_limit {
+     unsigned int sdp_cur_limit;
+     unsigned int dcp_cur_limit;
+     unsigned int cdp_cur_limit;
+     unsigned int aca_cur_limit;
+};
+
+struct usb_charger_nb {

include/linux/usb/usb_charger.h line 44

Quoted 6 lines

include/linux/usb/usb_charger.h new file +6 -0

+     struct notifier_block   nb;
+     struct usb_charger      *uchger;
+};
+
+struct usb_charger {
+     /* Internal data. Please do not set. */

Heh, as if people read comments :(

include/linux/usb/usb_charger.h line 45

Quoted 1 line

include/linux/usb/usb_charger.h new file +1 -0

+     const char              *name;

This isn't needed, use the one in your struct device.

include/linux/usb/usb_charger.h line 48

Quoted 3 lines

include/linux/usb/usb_charger.h new file +3 -0

+     struct device           dev;
+     struct raw_notifier_head        uchger_nh;
+     struct list_head        entry;

Why do you need another list? The device already is on a list.

include/linux/usb/usb_charger.h line 49

Quoted 1 line

include/linux/usb/usb_charger.h new file +1 -0

+     struct mutex            lock;

What is this protecting, document it.

thanks,

greg k-h

Quoted 7 lines · Greg KH

Quoted 5 lines · Baolin Wang

+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.

Quoted 2 lines

I have to ask, do you really mean "any later version"?

I think I did not get your point, could you explain it detailedly?

Quoted 8 lines · Baolin Wang via device-mainlining

Quoted 7 lines · Greg KH

Quoted 5 lines · Baolin Wang

+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.

Quoted 4 lines

Quoted 2 lines

I have to ask, do you really mean "any later version"?

I think I did not get your point, could you explain it detailedly?

The full kernel is licensed under v2 of the GPL only, not "any later version". See the second paragraph at the top of the COPYING file in the root directory of the kernel source tree. There are differences on individual files, but having this file allow "any later version" makes it different from much of rest of the kernel.

Unless you have a specific reason to allow greater-than-V2 GPL licensing on this file, you should change the licensing clause. The following wording appears to be pretty popular:

* 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.

-- Tim

Quoted 8 lines · Greg KH

Quoted 7 lines · Baolin Wang

Quoted 5 lines

+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.

Quoted 4 lines

Quoted 2 lines

I have to ask, do you really mean "any later version"?

I think I did not get your point, could you explain it detailedly?

The full kernel is licensed under v2 of the GPL only, not "any later version". See the second paragraph at the top of the COPYING file in the root directory of the kernel source tree. There are differences on individual files, but having this file allow "any later version" makes it different from much of rest of the kernel.

Unless you have a specific reason to allow greater-than-V2 GPL licensing on this file, you should change the licensing clause. The following wording appears to be pretty popular:

* 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.

Hi!

Quoted 24 lines · Baolin Wang via device-mainlining

Quoted 8 lines · Greg KH

Quoted 7 lines · Baolin Wang

Quoted 5 lines

+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.

Quoted 4 lines

Quoted 2 lines

I have to ask, do you really mean "any later version"?

I think I did not get your point, could you explain it detailedly?

The full kernel is licensed under v2 of the GPL only, not "any later version". See the second paragraph at the top of the COPYING file in the root directory of the kernel source tree. There are differences on individual files, but having this file allow "any later version" makes it different from much of rest of the kernel.

Unless you have a specific reason to allow greater-than-V2 GPL licensing on this file, you should change the licensing clause. The following wording appears to be pretty popular:

Quoted 3 lines

* 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.

Please, keep it V2 or later, if you can. It makes sharing code with U-Boot (for example) easier.

There's long tradition of "V2 or later" code in the kernel.

Quoted 8 lines

Quoted 3 lines

* 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.

Please, keep it V2 or later, if you can. It makes sharing code with U-Boot (for example) easier.

There's long tradition of "V2 or later" code in the kernel.

And there's even longer "v2 only" tradition as well. It's up to the person / company submitting the code to pick the license for it, let them make the decision please.

Quoted 5 lines

+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.

I have to ask, do you really mean "any later version"?

Hi!

Quoted 12 lines

Quoted 8 lines

Quoted 3 lines

* 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.

Please, keep it V2 or later, if you can. It makes sharing code with U-Boot (for example) easier.

There's long tradition of "V2 or later" code in the kernel.

And there's even longer "v2 only" tradition as well. It's up to the person / company submitting the code to pick the license for it, let them make the decision please.

Quoted 6 lines · You

Quoted 5 lines

+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.

Quoted 1 line

I have to ask, do you really mean "any later version"?

Given that you are quite high-level maintainer, that does not sound exactly like "let them make the decision". It sounds like a pressure to change the license to the one you liked. WHy did you have to ask?

Quoted 8 lines · Greg KH

Quoted 4 lines · Baolin Wang

+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.

I have to ask, do you really mean "any later version"?

I think I did not get your point, could you explain it detailedly?

Quoted 7 lines · Baolin Wang

Quoted 6 lines · Greg KH

Quoted 4 lines · Baolin Wang

+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.

Quoted 3 lines

Quoted 1 line

I have to ask, do you really mean "any later version"?

I think I did not get your point, could you explain it detailedly?

Unlike a lot of userspace projects the kernel is normally just licensed under GPLv2 without the option to relicense with a later version so the "...or any later version" is a bit unusual. There is some controversy about some of the changes in GPLv3.

Integrate with the newly added USB charger interface to limit the current we draw from the USB input based on the input device configuration identified by the USB stack, allowing us to charge more quickly from high current inputs without drawing more current than specified from others.

Signed-off-by Mark Brown <[email protected]>

Signed-off-by Baolin Wang <[email protected]>

---
 drivers/power/wm831x_power.c     |   69 ++++++++++++++++++++++++++++++++++++++
 include/linux/mfd/wm831x/pdata.h |    3 ++

 2 files changed, 72 insertions(+)

drivers/power/wm831x_power.c +69 -0

index db11ae6..72c661f 100644
@@ -13,6 +13,7 @@
 #include <linux/platform_device.h>
 #include <linux/power_supply.h>
 #include <linux/slab.h>
+#include <linux/usb/usb_charger.h>
 
 #include <linux/mfd/wm831x/core.h>
 #include <linux/mfd/wm831x/auxadc.h>

@@ -31,6 +32,8 @@ struct wm831x_power {
 	char usb_name[20];
 	char battery_name[20];
 	bool have_battery;
+	struct usb_charger *usb_charger;
+	struct notifier_block usb_notify;
 };
 
 static int wm831x_power_check_online(struct wm831x *wm831x, int supply,

@@ -125,6 +128,43 @@ static enum power_supply_property wm831x_usb_props[] = {
 	POWER_SUPPLY_PROP_VOLTAGE_NOW,
 };
 
+/* In miliamps */
+static unsigned int wm831x_usb_limits[] = {
+	0,
+	2,
+	100,
+	500,
+	900,
+	1500,
+	1800,
+	550,
+};
+
+static int wm831x_usb_limit_change(struct notifier_block *nb,
+				   unsigned long limit, void *data)
+{
+	struct wm831x_power *wm831x_power = container_of(nb,
+							 struct wm831x_power,
+							 usb_notify);
+	int i, best;
+
+	/* Find the highest supported limit */
+	best = 0;
+	for (i = 0; i < ARRAY_SIZE(wm831x_usb_limits); i++) {
+		if (limit < wm831x_usb_limits[i] &&
+		    wm831x_usb_limits[best] < wm831x_usb_limits[i])
+			best = i;
+	}
+
+	dev_dbg(wm831x_power->wm831x->dev,
+		"Limiting USB current to %dmA", wm831x_usb_limits[best]);
+
+	wm831x_set_bits(wm831x_power->wm831x, WM831X_POWER_STATE,
+		        WM831X_USB_ILIM_MASK, best);
+
+	return 0;
+}
+
 /*********************************************************************
  *		Battery properties
  *********************************************************************/

@@ -606,8 +646,31 @@ static int wm831x_power_probe(struct platform_device *pdev)
 		}
 	}
 
+	if (wm831x_pdata && wm831x_pdata->usb_gadget) {
+		power->usb_charger =
+			usb_charger_find_by_name(wm831x_pdata->usb_gadget);
+		if (IS_ERR(power->usb_charger)) {
+			ret = PTR_ERR(power->usb_charger);
+			dev_err(&pdev->dev,
+				"Failed to find USB gadget: %d\n", ret);
+			goto err_bat_irq;
+		}
+
+		power->usb_notify.notifier_call = wm831x_usb_limit_change;
+
+		ret = usb_charger_register_notify(power->usb_charger,
+						  &power->usb_notify);
+		if (ret != 0) {
+			dev_err(&pdev->dev,
+				"Failed to register notifier: %d\n", ret);
+			goto err_usb_charger;
+		}
+	}
+
 	return ret;
 
+err_usb_charger:
+	usb_charger_put(power->usb_charger);
 err_bat_irq:
 	--i;
 	for (; i >= 0; i--) {

@@ -637,6 +700,12 @@ static int wm831x_power_remove(struct platform_device *pdev)
 	struct wm831x *wm831x = wm831x_power->wm831x;
 	int irq, i;
 
+	if (wm831x_power->usb_charger) {
+		usb_charger_unregister_notify(wm831x_power->usb_charger,
+					      &wm831x_power->usb_notify);
+		usb_charger_put(wm831x_power->usb_charger);
+	}
+
 	for (i = 0; i < ARRAY_SIZE(wm831x_bat_irqs); i++) {
 		irq = wm831x_irq(wm831x, 
 				 platform_get_irq_byname(pdev,

include/linux/mfd/wm831x/pdata.h +3 -0

index dcc9631..5af8399 100644
@@ -126,6 +126,9 @@ struct wm831x_pdata {
 	/** The driver should initiate a power off sequence during shutdown */
 	bool soft_shutdown;
 
+	/** dev_name of USB charger gadget to integrate with */
+	const char *usb_gadget;
+
 	int irq_base;
 	int gpio_base;
 	int gpio_defaults[WM831X_GPIO_NUM];

Integrate with the newly added USB charger interface to limit the current we draw from the USB input based on the input device configuration identified by the USB stack, allowing us to charge more quickly from high current inputs without drawing more current than specified from others.

Signed-off-by Mark Brown <[email protected]>

Signed-off-by Baolin Wang <[email protected]>

---
 drivers/power/wm831x_power.c     |   69 ++++++++++++++++++++++++++++++++++++++
 include/linux/mfd/wm831x/pdata.h |    3 ++
 2 files changed, 72 insertions(+)

drivers/power/wm831x_power.c +4 -0

index db11ae6..72c661f 100644
@@ -13,6 +13,7 @@
 #include <linux/platform_device.h>
 #include <linux/power_supply.h>
 #include <linux/slab.h>
+#include <linux/usb/usb_charger.h>
 
 #include <linux/mfd/wm831x/core.h>
 #include <linux/mfd/wm831x/auxadc.h>

@@ -31,6 +32,8 @@ struct wm831x_power {
 	char usb_name[20];
 	char battery_name[20];
 	bool have_battery;
+	struct usb_charger *usb_charger;
+	struct notifier_block usb_notify;
 };
 
 static int wm831x_power_check_online(struct wm831x *wm831x, int supply,

@@ -125,6 +128,43 @@ static enum power_supply_property wm831x_usb_props[] = {
 	POWER_SUPPLY_PROP_VOLTAGE_NOW,
 };
 
+/* In miliamps */

drivers/power/wm831x_power.c +26 -0

+
+static int wm831x_usb_limit_change(struct notifier_block *nb,
+				   unsigned long limit, void *data)
+{
+	struct wm831x_power *wm831x_power = container_of(nb,
+							 struct wm831x_power,
+							 usb_notify);
+	int i, best;
+
+	/* Find the highest supported limit */
+	best = 0;
+	for (i = 0; i < ARRAY_SIZE(wm831x_usb_limits); i++) {
+		if (limit < wm831x_usb_limits[i] &&
+		    wm831x_usb_limits[best] < wm831x_usb_limits[i])
+			best = i;
+	}
+
+	dev_dbg(wm831x_power->wm831x->dev,
+		"Limiting USB current to %dmA", wm831x_usb_limits[best]);
+
+	wm831x_set_bits(wm831x_power->wm831x, WM831X_POWER_STATE,
+		        WM831X_USB_ILIM_MASK, best);
+
+	return 0;
+}
+
 /*********************************************************************
  *		Battery properties
  *********************************************************************/

drivers/power/wm831x_power.c +28 -0

+		power->usb_charger =
+			usb_charger_find_by_name(wm831x_pdata->usb_gadget);
+		if (IS_ERR(power->usb_charger)) {
+			ret = PTR_ERR(power->usb_charger);
+			dev_err(&pdev->dev,
+				"Failed to find USB gadget: %d\n", ret);
+			goto err_bat_irq;
+		}
+
+		power->usb_notify.notifier_call = wm831x_usb_limit_change;
+
+		ret = usb_charger_register_notify(power->usb_charger,
+						  &power->usb_notify);
+		if (ret != 0) {
+			dev_err(&pdev->dev,
+				"Failed to register notifier: %d\n", ret);
+			goto err_usb_charger;
+		}
+	}
+
 	return ret;
 
+err_usb_charger:
+	usb_charger_put(power->usb_charger);
 err_bat_irq:
 	--i;
 	for (; i >= 0; i--) {

@@ -637,6 +700,12 @@ static int wm831x_power_remove(struct platform_device *pdev)
 	struct wm831x *wm831x = wm831x_power->wm831x;
 	int irq, i;
 
+	if (wm831x_power->usb_charger) {
+		usb_charger_unregister_notify(wm831x_power->usb_charger,
+					      &wm831x_power->usb_notify);
+		usb_charger_put(wm831x_power->usb_charger);
+	}
+
 	for (i = 0; i < ARRAY_SIZE(wm831x_bat_irqs); i++) {
 		irq = wm831x_irq(wm831x, 
 				 platform_get_irq_byname(pdev,

include/linux/mfd/wm831x/pdata.h +3 -0

index dcc9631..5af8399 100644
@@ -126,6 +126,9 @@ struct wm831x_pdata {
 	/** The driver should initiate a power off sequence during shutdown */
 	bool soft_shutdown;
 
+	/** dev_name of USB charger gadget to integrate with */
+	const char *usb_gadget;
+
 	int irq_base;
 	int gpio_base;
 	int gpio_defaults[WM831X_GPIO_NUM];

Signature · 1 line

1.7.9.5

drivers/power/wm831x_power.c static enum power_supply_property wm831x_usb_props[] = { · line 141

Quoted 4 lines · Baolin Wang

drivers/power/wm831x_power.c +4 -0

+	1500,
+	1800,
+	550,
+};

Why 550 is the last, but not 1800?

drivers/power/wm831x_power.c static int wm831x_power_probe(struct platform_device *pdev) · line 649

Quoted 6 lines

*********************************************************************/

drivers/power/wm831x_power.c +1 -0

@@ -606,8 +646,31 @@ static int wm831x_power_probe(struct platform_device *pdev)
 		}
 	}
 
+	if (wm831x_pdata && wm831x_pdata->usb_gadget) {

Where the wm831x_pdata->usb_gadget is initialized?

Quoted 8 lines · Peter Chen

drivers/power/wm831x_power.c static enum power_supply_property wm831x_usb_props[] = { · line 141

Quoted 4 lines · Baolin Wang

drivers/power/wm831x_power.c +4 -0

+	1500,
+	1800,
+	550,
+};

Why 550 is the last, but not 1800?

You'd have to ask the hardware engineers who designed the chip. I suspect it's because 550 was added at a late stage in the design process but I'm basically just guessing there.

Quoted 4 lines

Quoted 4 lines

*********************************************************************/

(quoted diff) +0 -0

@@ -606,8 +646,31 @@ static int wm831x_power_probe(struct platform_device *pdev)
 		}
 	}

Quoted 3 lines

drivers/power/wm831x_power.c static int wm831x_power_probe(struct platform_device *pdev) · line 649

Quoted 1 line

drivers/power/wm831x_power.c +1 -0

+	if (wm831x_pdata && wm831x_pdata->usb_gadget) {

Where the wm831x_pdata->usb_gadget is initialized?

It's platform data, it will be initialised by whatever registers the platform data.

Quoted 2 lines · Mark Brown

Quoted 1 line · Peter Chen

On Fri, Aug 14, 2015 at 05:47:46PM +0800, Baolin Wang wrote:

Quoted 6 lines

Quoted 3 lines

drivers/power/wm831x_power.c static int wm831x_power_probe(struct platform_device *pdev) · line 649

Quoted 1 line

drivers/power/wm831x_power.c +1 -0

+	if (wm831x_pdata && wm831x_pdata->usb_gadget) {

Where the wm831x_pdata->usb_gadget is initialized?

It's platform data, it will be initialised by whatever registers the platform data.

passing pointers through pdata ?

Quoted 7 lines · Felipe Balbi

Quoted 6 lines · Mark Brown

Quoted 5 lines · Peter Chen

drivers/power/wm831x_power.c static int wm831x_power_probe(struct platform_device *pdev) · line 649

Quoted 1 line · Baolin Wang

drivers/power/wm831x_power.c +1 -0

+	if (wm831x_pdata && wm831x_pdata->usb_gadget) {

Where the wm831x_pdata->usb_gadget is initialized?

Quoted 4 lines

Quoted 2 lines

It's platform data, it will be initialised by whatever registers the platform data.

passing pointers through pdata ?

It's a char * to a name, not a pointer to struct.

Quoted 8 lines · Peter Chen

drivers/power/wm831x_power.c static enum power_supply_property wm831x_usb_props[] = { · line 141

Quoted 4 lines · Baolin Wang

drivers/power/wm831x_power.c +4 -0

+	1500,
+	1800,
+	550,
+};

Why 550 is the last, but not 1800?

You'd have to ask the hardware engineers who designed the chip. I suspect it's because 550 was added at a late stage in the design process but I'm basically just guessing there.

Quoted 5 lines

Quoted 5 lines

*********************************************************************/

(quoted diff) +0 -0

@@ -606,8 +646,31 @@ static int wm831x_power_probe(struct platform_device *pdev)
 		}
 	}

Quoted 3 lines

drivers/power/wm831x_power.c static int wm831x_power_probe(struct platform_device *pdev) · line 649

Quoted 1 line

drivers/power/wm831x_power.c +1 -0

+	if (wm831x_pdata && wm831x_pdata->usb_gadget) {

Where the wm831x_pdata->usb_gadget is initialized?

It's platform data, it will be initialised by whatever registers the platform data.

drivers/power/wm831x_power.c static enum power_supply_property wm831x_usb_props[] = { · line 154

Quoted 7 lines · Peter Chen

ok, I just had suspected below function's correctness, after looking it again, it always set 1800 as charging limit, does it be expected?

drivers/power/wm831x_power.c +4 -0

+       /* Find the highest supported limit */
+       best = 0;
+       for (i = 0; i < ARRAY_SIZE(wm831x_usb_limits); i++) {
+               if (limit < wm831x_usb_limits[i] &&

The above check is intended to ensure that we don't go over the limit that was passed in in the callback. The goal is to select the highest option that is less than the limit passed in.

Below code may be correct for the goal you expressed.

       for (i = 0; i < ARRAY_SIZE(wm831x_usb_limits); i++) {
               if (limit >= wm831x_usb_limits[i] &&
                   wm831x_usb_limits[best] < wm831x_usb_limits[i])
                       best = i;
       }

Sent: 14 August 2015 10:48
+/* In miliamps */

From: Baolin Wang

Quoted 2 lines

Sent: 14 August 2015 10:48
+/* In miliamps */

Spelling police: "milliamps"

drivers/power/wm831x_power.c static enum power_supply_property wm831x_usb_props[] = { · line 141

Quoted 10 lines

drivers/power/wm831x_power.c +10 -0

+static unsigned int wm831x_usb_limits[] = {
+     0,
+     2,
+     100,
+     500,
+     900,
+     1500,
+     1800,
+     550,
+};

David