linux-kernel - [PATCH] usb/gadget: make composite gadget meet usb compliance for vbus draw

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Date:	Thu, 23 Jul 2015 12:34:58 +0000
From:	"Du, Changbin" <changbin.du@...el.com>
To:	Felipe Balbi <balbi@...com>
CC:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: [PATCH] usb/gadget: make composite gadget meet usb compliance for
 vbus draw

>From 0a8e0d63a9887735c6782d7b0c15c2c1fdf1952a Mon Sep 17 00:00:00 2001
From: "Du, Changbin" <changbin.du@...el.com>
Date: Thu, 23 Jul 2015 20:08:04 +0800
Subject: [PATCH] usb/gadget: make composite gadget meet usb compliance for
 vbus draw

USB-IF compliance requirement limits the vbus current according to
current state. USB2 Spec requires that un-configured current must
be <= 100mA, for USB3 is 150mA, OTG is 2.5mA. So set corresponding
vbus draw current according to device mode.

Signed-off-by: Du, Changbin <changbin.du@...el.com>
---
 drivers/usb/gadget/composite.c | 39 ++++++++++++++++++++++++++++++++-------
 include/linux/usb/composite.h  |  8 ++++++++
 2 files changed, 40 insertions(+), 7 deletions(-)

diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
index 4e3447b..fdfd625 100644
--- a/drivers/usb/gadget/composite.c
+++ b/drivers/usb/gadget/composite.c
@@ -610,6 +610,21 @@ static void device_qual(struct usb_composite_dev *cdev)
 	qual->bRESERVED = 0;
 }
 
+static unsigned unconfigured_vbus_draw(struct usb_composite_dev *cdev)
+{
+	struct usb_gadget *g = cdev->gadget;
+	unsigned power;
+
+	if (gadget_is_otg(g))
+		power = USB_OTG_VBUS_DRAW_UNCONF;
+	else if (g->speed == USB_SPEED_SUPER)
+		power = USB3_VBUS_DRAW_UNCONF;
+	else
+		power = USB2_VBUS_DRAW_UNCONF;
+
+	return power;
+}
+
 /*-------------------------------------------------------------------------*/
 
 static void reset_config(struct usb_composite_dev *cdev)
@@ -634,7 +649,7 @@ static int set_config(struct usb_composite_dev *cdev,
 	struct usb_gadget	*gadget = cdev->gadget;
 	struct usb_configuration *c = NULL;
 	int			result = -EINVAL;
-	unsigned		power = gadget_is_otg(gadget) ? 8 : 100;
+	unsigned		power = unconfigured_vbus_draw(cdev);
 	int			tmp;
 
 	if (number) {
@@ -1829,6 +1844,15 @@ done:
 	return value;
 }
 
+static void composite_reset(struct usb_gadget *gadget)
+{
+	struct usb_composite_dev *cdev = get_gadget_data(gadget);
+
+	DBG(cdev, "reset\n");
+	usb_gadget_vbus_draw(gadget, unconfigured_vbus_draw(cdev));
+	composite_disconnect(gadget);
+}
+
 void composite_disconnect(struct usb_gadget *gadget)
 {
 	struct usb_composite_dev	*cdev = get_gadget_data(gadget);
@@ -2095,7 +2119,7 @@ void composite_suspend(struct usb_gadget *gadget)
 
 	cdev->suspended = 1;
 
-	usb_gadget_vbus_draw(gadget, 2);
+	usb_gadget_vbus_draw(gadget, USB_VBUS_DRAW_SUSPEND);
 }
 
 void composite_resume(struct usb_gadget *gadget)
@@ -2117,10 +2141,11 @@ void composite_resume(struct usb_gadget *gadget)
 		}
 
 		maxpower = cdev->config->MaxPower;
-
-		usb_gadget_vbus_draw(gadget, maxpower ?
-			maxpower : CONFIG_USB_GADGET_VBUS_DRAW);
-	}
+		if (!maxpower)
+			maxpower = CONFIG_USB_GADGET_VBUS_DRAW;
+	} else
+		maxpower = unconfigured_vbus_draw(cdev);
+	usb_gadget_vbus_draw(gadget, maxpower);
 
 	cdev->suspended = 0;
 }
@@ -2132,7 +2157,7 @@ static const struct usb_gadget_driver composite_driver_template = {
 	.unbind		= composite_unbind,
 
 	.setup		= composite_setup,
-	.reset		= composite_disconnect,
+	.reset		= composite_reset,
 	.disconnect	= composite_disconnect,
 
 	.suspend	= composite_suspend,
diff --git a/include/linux/usb/composite.h b/include/linux/usb/composite.h
index 2511469..90b434d 100644
--- a/include/linux/usb/composite.h
+++ b/include/linux/usb/composite.h
@@ -333,6 +333,14 @@ enum {
 	USB_GADGET_FIRST_AVAIL_IDX,
 };
 
+/* USB2 compliance requires that un-configured current draw <= 100mA,
+ * USB3 requires it <= 150mA, OTG requires it <= 2.5mA.
+ */
+#define USB2_VBUS_DRAW_UNCONF		100
+#define USB3_VBUS_DRAW_UNCONF		150
+#define USB_OTG_VBUS_DRAW_UNCONF	2
+#define USB_VBUS_DRAW_SUSPEND		2
+
 /**
  * struct usb_composite_driver - groups configurations into a gadget
  * @name: For diagnostics, identifies the driver.
-- 
2.1.4

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