USB: EHCI Debug Port Device Gadget

This is a patch that implements an USB EHCI Debug Device using the
Gadget API. This patch applies to a 2.6.35-rc3 kernel.

The gadget needs a compliant usb controller that forwards the
USB_DEVICE_DEBUG_MODE feature to its gadget.

The gadget provides two configuration modes, one that only printk() the
received data, and one that exposes a serial device to userland
(/dev/ttyGSxxx).

The gadget has been tested on an IGEPv2 board running a 2.6.35-rc1
kernel. The debug port was fed on the host side by a 2.6.34 kernel.
Signed-off-by: Stephane Duverger <stephane.duverger@gmail.com>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/gadget/Kconfig

@@ -915,6 +915,34 @@ config USB_G_HID
 	  Say "y" to link the driver statically, or "m" to build a
 	  dynamically linked module called "g_hid".
 
+config USB_G_DBGP
+	tristate "EHCI Debug Device Gadget"
+	help
+	  This gadget emulates an EHCI Debug device. This is useful when you want
+	  to interact with an EHCI Debug Port.
+
+	  Say "y" to link the driver statically, or "m" to build a
+	  dynamically linked module called "g_dbgp".
+
+if USB_G_DBGP
+choice
+	prompt "EHCI Debug Device mode"
+	default USB_G_DBGP_SERIAL
+
+config USB_G_DBGP_PRINTK
+	depends on USB_G_DBGP
+	bool "printk"
+	help
+	  Directly printk() received data. No interaction.
+
+config USB_G_DBGP_SERIAL
+	depends on USB_G_DBGP
+	bool "serial"
+	help
+	  Userland can interact using /dev/ttyGSxxx.
+endchoice
+endif
+
 # put drivers that need isochronous transfer support (for audio
 # or video class gadget drivers), or specific hardware, here.
 config USB_G_WEBCAM

drivers/usb/gadget/Makefile

@@ -44,6 +44,7 @@ g_printer-objs			:= printer.o
 g_cdc-objs			:= cdc2.o
 g_multi-objs			:= multi.o
 g_hid-objs			:= hid.o
+g_dbgp-objs			:= dbgp.o
 g_nokia-objs			:= nokia.o
 g_webcam-objs			:= webcam.o
 
@@ -60,6 +61,7 @@ obj-$(CONFIG_USB_G_PRINTER)	+= g_printer.o
 obj-$(CONFIG_USB_MIDI_GADGET)	+= g_midi.o
 obj-$(CONFIG_USB_CDC_COMPOSITE) += g_cdc.o
 obj-$(CONFIG_USB_G_HID)		+= g_hid.o
+obj-$(CONFIG_USB_G_DBGP)	+= g_dbgp.o
 obj-$(CONFIG_USB_G_MULTI)	+= g_multi.o
 obj-$(CONFIG_USB_G_NOKIA)	+= g_nokia.o
 obj-$(CONFIG_USB_G_WEBCAM)	+= g_webcam.o

drivers/usb/gadget/dbgp.c

+/*
+ * dbgp.c -- EHCI Debug Port device gadget
+ *
+ * Copyright (C) 2010 Stephane Duverger
+ *
+ * Released under the GPLv2.
+ *
+ */
+
+/* verbose messages */
+#include <linux/kernel.h>
+#include <linux/device.h>
+#include <linux/usb/ch9.h>
+#include <linux/usb/gadget.h>
+
+/* See comments in "zero.c" */
+#include "epautoconf.c"
+
+#ifdef CONFIG_USB_G_DBGP_SERIAL
+#include "u_serial.c"
+#endif
+
+#define DRIVER_VENDOR_ID	0x0525 /* NetChip */
+#define DRIVER_PRODUCT_ID	0xc0de /* undefined */
+
+#define USB_DEBUG_MAX_PACKET_SIZE     8
+#define DBGP_REQ_EP0_LEN              128
+#define DBGP_REQ_LEN                  512
+
+static struct dbgp {
+	struct usb_gadget  *gadget;
+	struct usb_request *req;
+	struct usb_ep      *i_ep;
+	struct usb_ep      *o_ep;
+#ifdef CONFIG_USB_G_DBGP_SERIAL
+	struct gserial     *serial;
+#endif
+} dbgp;
+
+static struct usb_device_descriptor device_desc = {
+	.bLength = sizeof device_desc,
+	.bDescriptorType = USB_DT_DEVICE,
+	.bcdUSB = __constant_cpu_to_le16(0x0200),
+	.bDeviceClass =	USB_CLASS_VENDOR_SPEC,
+	.idVendor = __constant_cpu_to_le16(DRIVER_VENDOR_ID),
+	.idProduct = __constant_cpu_to_le16(DRIVER_PRODUCT_ID),
+	.bNumConfigurations = 1,
+};
+
+static struct usb_debug_descriptor dbg_desc = {
+	.bLength = sizeof dbg_desc,
+	.bDescriptorType = USB_DT_DEBUG,
+};
+
+static struct usb_endpoint_descriptor i_desc = {
+	.bLength = USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType = USB_DT_ENDPOINT,
+	.bmAttributes = USB_ENDPOINT_XFER_BULK,
+	.bEndpointAddress = USB_DIR_IN,
+};
+
+static struct usb_endpoint_descriptor o_desc = {
+	.bLength = USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType = USB_DT_ENDPOINT,
+	.bmAttributes = USB_ENDPOINT_XFER_BULK,
+	.bEndpointAddress = USB_DIR_OUT,
+};
+
+#ifdef CONFIG_USB_G_DBGP_PRINTK
+static int dbgp_consume(char *buf, unsigned len)
+{
+	char c;
+
+	if (!len)
+		return 0;
+
+	c = buf[len-1];
+	if (c != 0)
+		buf[len-1] = 0;
+
+	printk(KERN_NOTICE "%s%c", buf, c);
+	return 0;
+}
+
+static void __disable_ep(struct usb_ep *ep)
+{
+	if (ep && ep->driver_data == dbgp.gadget) {
+		usb_ep_disable(ep);
+		ep->driver_data = NULL;
+	}
+}
+
+static void dbgp_disable_ep(void)
+{
+	__disable_ep(dbgp.i_ep);
+	__disable_ep(dbgp.o_ep);
+}
+
+static void dbgp_complete(struct usb_ep *ep, struct usb_request *req)
+{
+	int stp;
+	int err = 0;
+	int status = req->status;
+
+	if (ep == dbgp.i_ep) {
+		stp = 1;
+		goto fail;
+	}
+
+	if (status != 0) {
+		stp = 2;
+		goto release_req;
+	}
+
+	dbgp_consume(req->buf, req->actual);
+
+	req->length = DBGP_REQ_LEN;
+	err = usb_ep_queue(ep, req, GFP_ATOMIC);
+	if (err < 0) {
+		stp = 3;
+		goto release_req;
+	}
+
+	return;
+
+release_req:
+	kfree(req->buf);
+	usb_ep_free_request(dbgp.o_ep, req);
+	dbgp_disable_ep();
+fail:
+	dev_dbg(&dbgp.gadget->dev,
+		"complete: failure (%d:%d) ==> %d\n", stp, err, status);
+}
+
+static int dbgp_enable_ep_req(struct usb_ep *ep)
+{
+	int err, stp;
+	struct usb_request *req;
+
+	req = usb_ep_alloc_request(ep, GFP_KERNEL);
+	if (!req) {
+		err = -ENOMEM;
+		stp = 1;
+		goto fail_1;
+	}
+
+	req->buf = kmalloc(DBGP_REQ_LEN, GFP_KERNEL);
+	if (!req->buf) {
+		err = -ENOMEM;
+		stp = 2;
+		goto fail_2;
+	}
+
+	req->complete = dbgp_complete;
+	req->length = DBGP_REQ_LEN;
+	err = usb_ep_queue(ep, req, GFP_ATOMIC);
+	if (err < 0) {
+		stp = 3;
+		goto fail_3;
+	}
+
+	return 0;
+
+fail_3:
+	kfree(req->buf);
+fail_2:
+	usb_ep_free_request(dbgp.o_ep, req);
+fail_1:
+	dev_dbg(&dbgp.gadget->dev,
+		"enable ep req: failure (%d:%d)\n", stp, err);
+	return err;
+}
+
+static int __enable_ep(struct usb_ep *ep, struct usb_endpoint_descriptor *desc)
+{
+	int err = usb_ep_enable(ep, desc);
+	ep->driver_data = dbgp.gadget;
+	return err;
+}
+
+static int dbgp_enable_ep(void)
+{
+	int err, stp;
+
+	err = __enable_ep(dbgp.i_ep, &i_desc);
+	if (err < 0) {
+		stp = 1;
+		goto fail_1;
+	}
+
+	err = __enable_ep(dbgp.o_ep, &o_desc);
+	if (err < 0) {
+		stp = 2;
+		goto fail_2;
+	}
+
+	err = dbgp_enable_ep_req(dbgp.o_ep);
+	if (err < 0) {
+		stp = 3;
+		goto fail_3;
+	}
+
+	return 0;
+
+fail_3:
+	__disable_ep(dbgp.o_ep);
+fail_2:
+	__disable_ep(dbgp.i_ep);
+fail_1:
+	dev_dbg(&dbgp.gadget->dev, "enable ep: failure (%d:%d)\n", stp, err);
+	return err;
+}
+#endif
+
+static void dbgp_disconnect(struct usb_gadget *gadget)
+{
+#ifdef CONFIG_USB_G_DBGP_PRINTK
+	dbgp_disable_ep();
+#else
+	gserial_disconnect(dbgp.serial);
+#endif
+}
+
+static void dbgp_unbind(struct usb_gadget *gadget)
+{
+#ifdef CONFIG_USB_G_DBGP_SERIAL
+	kfree(dbgp.serial);
+#endif
+	if (dbgp.req) {
+		kfree(dbgp.req->buf);
+		usb_ep_free_request(gadget->ep0, dbgp.req);
+	}
+
+	gadget->ep0->driver_data = NULL;
+}
+
+static int __init dbgp_configure_endpoints(struct usb_gadget *gadget)
+{
+	int stp;
+
+	usb_ep_autoconfig_reset(gadget);
+
+	dbgp.i_ep = usb_ep_autoconfig(gadget, &i_desc);
+	if (!dbgp.i_ep) {
+		stp = 1;
+		goto fail_1;
+	}
+
+	dbgp.i_ep->driver_data = gadget;
+	i_desc.wMaxPacketSize =
+		__constant_cpu_to_le16(USB_DEBUG_MAX_PACKET_SIZE);
+
+	dbgp.o_ep = usb_ep_autoconfig(gadget, &o_desc);
+	if (!dbgp.o_ep) {
+		dbgp.i_ep->driver_data = NULL;
+		stp = 2;
+		goto fail_2;
+	}
+
+	dbgp.o_ep->driver_data = gadget;
+	o_desc.wMaxPacketSize =
+		__constant_cpu_to_le16(USB_DEBUG_MAX_PACKET_SIZE);
+
+	dbg_desc.bDebugInEndpoint = i_desc.bEndpointAddress & 0x7f;
+	dbg_desc.bDebugOutEndpoint = o_desc.bEndpointAddress & 0x7f;
+
+#ifdef CONFIG_USB_G_DBGP_SERIAL
+	dbgp.serial->in = dbgp.i_ep;
+	dbgp.serial->out = dbgp.o_ep;
+
+	dbgp.serial->in_desc = &i_desc;
+	dbgp.serial->out_desc = &o_desc;
+
+	if (gserial_setup(gadget, 1) < 0) {
+		stp = 3;
+		goto fail_3;
+	}
+
+	return 0;
+
+fail_3:
+	dbgp.o_ep->driver_data = NULL;
+#else
+	return 0;
+#endif
+fail_2:
+	dbgp.i_ep->driver_data = NULL;
+fail_1:
+	dev_dbg(&dbgp.gadget->dev, "ep config: failure (%d)\n", stp);
+	return -ENODEV;
+}
+
+static int __init dbgp_bind(struct usb_gadget *gadget)
+{
+	int err, stp;
+
+	dbgp.gadget = gadget;
+
+	dbgp.req = usb_ep_alloc_request(gadget->ep0, GFP_KERNEL);
+	if (!dbgp.req) {
+		err = -ENOMEM;
+		stp = 1;
+		goto fail;
+	}
+
+	dbgp.req->buf = kmalloc(DBGP_REQ_EP0_LEN, GFP_KERNEL);
+	if (!dbgp.req->buf) {
+		err = -ENOMEM;
+		stp = 2;
+		goto fail;
+	}
+
+	dbgp.req->length = DBGP_REQ_EP0_LEN;
+	gadget->ep0->driver_data = gadget;
+
+#ifdef CONFIG_USB_G_DBGP_SERIAL
+	dbgp.serial = kzalloc(sizeof(struct gserial), GFP_KERNEL);
+	if (!dbgp.serial) {
+		stp = 3;
+		err = -ENOMEM;
+		goto fail;
+	}
+#endif
+	err = dbgp_configure_endpoints(gadget);
+	if (err < 0) {
+		stp = 4;
+		goto fail;
+	}
+
+	dev_dbg(&dbgp.gadget->dev, "bind: success\n");
+	return 0;
+
+fail:
+	dev_dbg(&gadget->dev, "bind: failure (%d:%d)\n", stp, err);
+	dbgp_unbind(gadget);
+	return err;
+}
+
+static void dbgp_setup_complete(struct usb_ep *ep,
+				struct usb_request *req)
+{
+	dev_dbg(&dbgp.gadget->dev, "setup complete: %d, %d/%d\n",
+		req->status, req->actual, req->length);
+}
+
+static int dbgp_setup(struct usb_gadget *gadget,
+		      const struct usb_ctrlrequest *ctrl)
+{
+	struct usb_request *req = dbgp.req;
+	u8 request = ctrl->bRequest;
+	u16 value = le16_to_cpu(ctrl->wValue);
+	u16 length = le16_to_cpu(ctrl->wLength);
+	int err = 0;
+	void *data;
+	u16 len;
+
+	gadget->ep0->driver_data = gadget;
+
+	if (request == USB_REQ_GET_DESCRIPTOR) {
+		switch (value>>8) {
+		case USB_DT_DEVICE:
+			dev_dbg(&dbgp.gadget->dev, "setup: desc device\n");
+			len = sizeof device_desc;
+			data = &device_desc;
+			break;
+		case USB_DT_DEBUG:
+			dev_dbg(&dbgp.gadget->dev, "setup: desc debug\n");
+			len = sizeof dbg_desc;
+			data = &dbg_desc;
+			break;
+		default:
+			goto fail;
+		}
+	} else if (request == USB_REQ_SET_FEATURE &&
+		   value == USB_DEVICE_DEBUG_MODE) {
+		len = 0;
+		data = NULL;
+		dev_dbg(&dbgp.gadget->dev, "setup: feat debug\n");
+#ifdef CONFIG_USB_G_DBGP_PRINTK
+		err = dbgp_enable_ep();
+#else
+		err = gserial_connect(dbgp.serial, 0);
+#endif
+		if (err < 0)
+			goto fail;
+	} else
+		goto fail;
+
+	if (len >= 0) {
+		req->length = min(length, len);
+		req->zero = len < req->length;
+		if (data && req->length)
+			memcpy(req->buf, data, req->length);
+
+		req->complete = dbgp_setup_complete;
+		return usb_ep_queue(gadget->ep0, req, GFP_ATOMIC);
+	}
+
+fail:
+	dev_dbg(&dbgp.gadget->dev,
+		"setup: failure req %x v %x\n", request, value);
+	return err;
+}
+
+static struct usb_gadget_driver dbgp_driver = {
+	.function = "dbgp",
+	.speed = USB_SPEED_HIGH,
+	.bind = dbgp_bind,
+	.unbind = dbgp_unbind,
+	.setup = dbgp_setup,
+	.disconnect = dbgp_disconnect,
+	.driver	= {
+		.owner = THIS_MODULE,
+		.name = "dbgp"
+	},
+};
+
+static int __init dbgp_init(void)
+{
+	return usb_gadget_register_driver(&dbgp_driver);
+}
+
+static void __exit dbgp_exit(void)
+{
+	usb_gadget_unregister_driver(&dbgp_driver);
+#ifdef CONFIG_USB_G_DBGP_SERIAL
+	gserial_cleanup();
+#endif
+}
+
+MODULE_AUTHOR("Stephane Duverger");
+MODULE_LICENSE("GPL");
+module_init(dbgp_init);
+module_exit(dbgp_exit);