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>

3 files changed, 464 insertions, 0 deletions

diff --git a/drivers/usb/gadget/Kconfig b/drivers/usb/gadget/Kconfig
index dd3b25101858..cd27f9bde2c8 100644
--- a/drivers/usb/gadget/Kconfig
+++ b/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
diff --git a/drivers/usb/gadget/Makefile b/drivers/usb/gadget/Makefile
index 9bcde110feb1..397b892e90e2 100644
--- a/drivers/usb/gadget/Makefile
+++ b/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
diff --git a/drivers/usb/gadget/dbgp.c b/drivers/usb/gadget/dbgp.c
new file mode 100644
index 000000000000..0ed50a2c0a36
--- /dev/null
+++ b/drivers/usb/gadget/dbgp.c
@@ -0,0 +1,434 @@
+/*
+ * 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);