usb gadget zero: split out loopback config

This splits the gadget zero "loopback" configuration into a standalone
"configuration driver", building on the composite gadget framework code.
It doesn't yet pull the original code out of gadget zero or update how
that driver is built.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

2 files changed, 383 insertions, 0 deletions

diff --git a/drivers/usb/gadget/f_loopback.c b/drivers/usb/gadget/f_loopback.c
new file mode 100644
index 000000000000..eda4cde72c82
--- /dev/null
+++ b/drivers/usb/gadget/f_loopback.c
@@ -0,0 +1,381 @@
+/*
+ * f_loopback.c - USB peripheral loopback configuration driver
+ *
+ * Copyright (C) 2003-2008 David Brownell
+ * Copyright (C) 2008 by Nokia Corporation
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+/* #define VERBOSE_DEBUG */
+
+#include <linux/kernel.h>
+#include <linux/utsname.h>
+#include <linux/device.h>
+
+#include "g_zero.h"
+#include "gadget_chips.h"
+
+
+/*
+ * LOOPBACK FUNCTION ... a testing vehicle for USB peripherals,
+ *
+ * This takes messages of various sizes written OUT to a device, and loops
+ * them back so they can be read IN from it.  It has been used by certain
+ * test applications.  It supports limited testing of data queueing logic.
+ *
+ *
+ * This is currently packaged as a configuration driver, which can't be
+ * combined with other functions to make composite devices.  However, it
+ * can be combined with other independent configurations.
+ */
+struct f_loopback {
+        struct usb_function     function;
+
+        struct usb_ep           *in_ep;
+        struct usb_ep           *out_ep;
+};
+
+static inline struct f_loopback *func_to_loop(struct usb_function *f)
+{
+        return container_of(f, struct f_loopback, function);
+}
+
+static unsigned qlen = 32;
+module_param(qlen, uint, 0);
+MODULE_PARM_DESC(qlenn, "depth of loopback queue");
+
+/*-------------------------------------------------------------------------*/
+
+static struct usb_interface_descriptor loopback_intf = {
+        .bLength =              sizeof loopback_intf,
+        .bDescriptorType =      USB_DT_INTERFACE,
+
+        .bNumEndpoints =        2,
+        .bInterfaceClass =      USB_CLASS_VENDOR_SPEC,
+        /* .iInterface = DYNAMIC */
+};
+
+/* full speed support: */
+
+static struct usb_endpoint_descriptor fs_source_desc = {
+        .bLength =              USB_DT_ENDPOINT_SIZE,
+        .bDescriptorType =      USB_DT_ENDPOINT,
+
+        .bEndpointAddress =     USB_DIR_IN,
+        .bmAttributes =         USB_ENDPOINT_XFER_BULK,
+};
+
+static struct usb_endpoint_descriptor fs_sink_desc = {
+        .bLength =              USB_DT_ENDPOINT_SIZE,
+        .bDescriptorType =      USB_DT_ENDPOINT,
+
+        .bEndpointAddress =     USB_DIR_OUT,
+        .bmAttributes =         USB_ENDPOINT_XFER_BULK,
+};
+
+static struct usb_descriptor_header *fs_loopback_descs[] = {
+        (struct usb_descriptor_header *) &loopback_intf,
+        (struct usb_descriptor_header *) &fs_sink_desc,
+        (struct usb_descriptor_header *) &fs_source_desc,
+        NULL,
+};
+
+/* high speed support: */
+
+static struct usb_endpoint_descriptor hs_source_desc = {
+        .bLength =              USB_DT_ENDPOINT_SIZE,
+        .bDescriptorType =      USB_DT_ENDPOINT,
+
+        .bmAttributes =         USB_ENDPOINT_XFER_BULK,
+        .wMaxPacketSize =       __constant_cpu_to_le16(512),
+};
+
+static struct usb_endpoint_descriptor hs_sink_desc = {
+        .bLength =              USB_DT_ENDPOINT_SIZE,
+        .bDescriptorType =      USB_DT_ENDPOINT,
+
+        .bmAttributes =         USB_ENDPOINT_XFER_BULK,
+        .wMaxPacketSize =       __constant_cpu_to_le16(512),
+};
+
+static struct usb_descriptor_header *hs_loopback_descs[] = {
+        (struct usb_descriptor_header *) &loopback_intf,
+        (struct usb_descriptor_header *) &hs_source_desc,
+        (struct usb_descriptor_header *) &hs_sink_desc,
+        NULL,
+};
+
+/* function-specific strings: */
+
+static struct usb_string strings_loopback[] = {
+        [0].s = "loop input to output",
+        {  }                    /* end of list */
+};
+
+static struct usb_gadget_strings stringtab_loop = {
+        .language       = 0x0409,       /* en-us */
+        .strings        = strings_loopback,
+};
+
+static struct usb_gadget_strings *loopback_strings[] = {
+        &stringtab_loop,
+        NULL,
+};
+
+/*-------------------------------------------------------------------------*/
+
+static int __init
+loopback_bind(struct usb_configuration *c, struct usb_function *f)
+{
+        struct usb_composite_dev *cdev = c->cdev;
+        struct f_loopback       *loop = func_to_loop(f);
+        int                     id;
+
+        /* allocate interface ID(s) */
+        id = usb_interface_id(c, f);
+        if (id < 0)
+                return id;
+        loopback_intf.bInterfaceNumber = id;
+
+        /* allocate endpoints */
+
+        loop->in_ep = usb_ep_autoconfig(cdev->gadget, &fs_source_desc);
+        if (!loop->in_ep) {
+autoconf_fail:
+                ERROR(cdev, "%s: can't autoconfigure on %s\n",
+                        f->name, cdev->gadget->name);
+                return -ENODEV;
+        }
+        loop->in_ep->driver_data = cdev;        /* claim */
+
+        loop->out_ep = usb_ep_autoconfig(cdev->gadget, &fs_sink_desc);
+        if (!loop->out_ep)
+                goto autoconf_fail;
+        loop->out_ep->driver_data = cdev;       /* claim */
+
+        /* support high speed hardware */
+        if (gadget_is_dualspeed(c->cdev->gadget)) {
+                hs_source_desc.bEndpointAddress =
+                                fs_source_desc.bEndpointAddress;
+                hs_sink_desc.bEndpointAddress =
+                                fs_sink_desc.bEndpointAddress;
+                f->hs_descriptors = hs_loopback_descs;
+        }
+
+        DBG(cdev, "%s speed %s: IN/%s, OUT/%s\n",
+                        gadget_is_dualspeed(c->cdev->gadget) ? "dual" : "full",
+                        f->name, loop->in_ep->name, loop->out_ep->name);
+        return 0;
+}
+
+static void
+loopback_unbind(struct usb_configuration *c, struct usb_function *f)
+{
+        kfree(func_to_loop(f));
+}
+
+static void loopback_complete(struct usb_ep *ep, struct usb_request *req)
+{
+        struct f_loopback       *loop = ep->driver_data;
+        struct usb_composite_dev *cdev = loop->function.config->cdev;
+        int                     status = req->status;
+
+        switch (status) {
+
+        case 0:                         /* normal completion? */
+                if (ep == loop->out_ep) {
+                        /* loop this OUT packet back IN to the host */
+                        req->zero = (req->actual < req->length);
+                        req->length = req->actual;
+                        status = usb_ep_queue(loop->in_ep, req, GFP_ATOMIC);
+                        if (status == 0)
+                                return;
+
+                        /* "should never get here" */
+                        ERROR(cdev, "can't loop %s to %s: %d\n",
+                                ep->name, loop->in_ep->name,
+                                status);
+                }
+
+                /* queue the buffer for some later OUT packet */
+                req->length = buflen;
+                status = usb_ep_queue(loop->out_ep, req, GFP_ATOMIC);
+                if (status == 0)
+                        return;
+
+                /* "should never get here" */
+                /* FALLTHROUGH */
+
+        default:
+                ERROR(cdev, "%s loop complete --> %d, %d/%d\n", ep->name,
+                                status, req->actual, req->length);
+                /* FALLTHROUGH */
+
+        /* NOTE:  since this driver doesn't maintain an explicit record
+         * of requests it submitted (just maintains qlen count), we
+         * rely on the hardware driver to clean up on disconnect or
+         * endpoint disable.
+         */
+        case -ECONNABORTED:             /* hardware forced ep reset */
+        case -ECONNRESET:               /* request dequeued */
+        case -ESHUTDOWN:                /* disconnect from host */
+                free_ep_req(ep, req);
+                return;
+        }
+}
+
+static void disable_loopback(struct f_loopback *loop)
+{
+        struct usb_composite_dev        *cdev;
+
+        cdev = loop->function.config->cdev;
+        disable_endpoints(cdev, loop->in_ep, loop->out_ep);
+        VDBG(cdev, "%s disabled\n", loop->function.name);
+}
+
+static int
+enable_loopback(struct usb_composite_dev *cdev, struct f_loopback *loop)
+{
+        int                                     result = 0;
+        const struct usb_endpoint_descriptor    *src, *sink;
+        struct usb_ep                           *ep;
+        struct usb_request                      *req;
+        unsigned                                i;
+
+        src = ep_choose(cdev->gadget, &hs_source_desc, &fs_source_desc);
+        sink = ep_choose(cdev->gadget, &hs_sink_desc, &fs_sink_desc);
+
+        /* one endpoint writes data back IN to the host */
+        ep = loop->in_ep;
+        result = usb_ep_enable(ep, src);
+        if (result < 0)
+                return result;
+        ep->driver_data = loop;
+
+        /* one endpoint just reads OUT packets */
+        ep = loop->out_ep;
+        result = usb_ep_enable(ep, sink);
+        if (result < 0) {
+fail0:
+                ep = loop->in_ep;
+                usb_ep_disable(ep);
+                ep->driver_data = NULL;
+                return result;
+        }
+        ep->driver_data = loop;
+
+        /* allocate a bunch of read buffers and queue them all at once.
+         * we buffer at most 'qlen' transfers; fewer if any need more
+         * than 'buflen' bytes each.
+         */
+        for (i = 0; i < qlen && result == 0; i++) {
+                req = alloc_ep_req(ep);
+                if (req) {
+                        req->complete = loopback_complete;
+                        result = usb_ep_queue(ep, req, GFP_ATOMIC);
+                        if (result)
+                                ERROR(cdev, "%s queue req --> %d\n",
+                                                ep->name, result);
+                } else {
+                        usb_ep_disable(ep);
+                        ep->driver_data = NULL;
+                        result = -ENOMEM;
+                        goto fail0;
+                }
+        }
+
+        DBG(cdev, "%s enabled\n", loop->function.name);
+        return result;
+}
+
+static int loopback_set_alt(struct usb_function *f,
+                unsigned intf, unsigned alt)
+{
+        struct f_loopback       *loop = func_to_loop(f);
+        struct usb_composite_dev *cdev = f->config->cdev;
+
+        /* we know alt is zero */
+        if (loop->in_ep->driver_data)
+                disable_loopback(loop);
+        return enable_loopback(cdev, loop);
+}
+
+static void loopback_disable(struct usb_function *f)
+{
+        struct f_loopback       *loop = func_to_loop(f);
+
+        disable_loopback(loop);
+}
+
+/*-------------------------------------------------------------------------*/
+
+static int __init loopback_bind_config(struct usb_configuration *c)
+{
+        struct f_loopback       *loop;
+        int                     status;
+
+        loop = kzalloc(sizeof *loop, GFP_KERNEL);
+        if (!loop)
+                return -ENOMEM;
+
+        loop->function.name = "loopback";
+        loop->function.descriptors = fs_loopback_descs;
+        loop->function.bind = loopback_bind;
+        loop->function.unbind = loopback_unbind;
+        loop->function.set_alt = loopback_set_alt;
+        loop->function.disable = loopback_disable;
+
+        status = usb_add_function(c, &loop->function);
+        if (status)
+                kfree(loop);
+        return status;
+}
+
+static struct usb_configuration loopback_driver = {
+        .label          = "loopback",
+        .strings        = loopback_strings,
+        .bind           = loopback_bind_config,
+        .bConfigurationValue = 2,
+        .bmAttributes   = USB_CONFIG_ATT_SELFPOWER,
+        .bMaxPower      = 1,    /* 2 mA, minimal */
+        /* .iConfiguration = DYNAMIC */
+};
+
+/**
+ * loopback_add - add a loopback testing configuration to a device
+ * @cdev: the device to support the loopback configuration
+ */
+int __init loopback_add(struct usb_composite_dev *cdev)
+{
+        int id;
+
+        /* allocate string ID(s) */
+        id = usb_string_id(cdev);
+        if (id < 0)
+                return id;
+        strings_loopback[0].id = id;
+
+        loopback_intf.iInterface = id;
+        loopback_driver.iConfiguration = id;
+
+        /* support OTG systems */
+        if (gadget_is_otg(cdev->gadget)) {
+                loopback_driver.descriptors = otg_desc;
+                loopback_driver.bmAttributes |= USB_CONFIG_ATT_WAKEUP;
+        }
+
+        return usb_add_config(cdev, &loopback_driver);
+}
diff --git a/drivers/usb/gadget/g_zero.h b/drivers/usb/gadget/g_zero.h
index 2781221b9469..dd2f16ad5a88 100644
--- a/drivers/usb/gadget/g_zero.h
+++ b/drivers/usb/gadget/g_zero.h
@@ -9,6 +9,7 @@
 #include <linux/usb/composite.h>
 
 /* global state */
+extern unsigned buflen;
 extern const struct usb_descriptor_header *otg_desc[];
 
 /* common utilities */
@@ -19,5 +20,6 @@ void disable_endpoints(struct usb_composite_dev *cdev,
 
 /* configuration-specific linkup */
 int sourcesink_add(struct usb_composite_dev *cdev);
+int loopback_add(struct usb_composite_dev *cdev);
 
 #endif /* __G_ZERO_H */