USB: gadget: Add EEM gadget driver

This patch adds a CDC EEM ethernet gadget driver.  CDC EEM is a newer
USB ethernet specification that uses a simpler interface than the older
CDC ECM.  This makes CDC EEM usable by a wider set of USB hardware.
By default the ethernet gadget will still use CDC ECM/Subset, but kernel
configuration and/or a module parameter will allow alternative use of
the CDC EEM protocol.

Changes since last version:
	- Brought in missing RNDIS changes that caused compile error
	- Modified 'sentinel CRC' checking to match EEM host driver

Signed-off-by: Brian Niebuhr <bniebuhr@efjohnson.com>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 562 insertions, 0 deletions

diff --git a/drivers/usb/gadget/f_eem.c b/drivers/usb/gadget/f_eem.c
new file mode 100644
index 00000000000..0a577d5694f
--- /dev/null
+++ b/drivers/usb/gadget/f_eem.c
@@ -0,0 +1,562 @@
+/*
+ * f_eem.c -- USB CDC Ethernet (EEM) link function driver
+ *
+ * Copyright (C) 2003-2005,2008 David Brownell
+ * Copyright (C) 2008 Nokia Corporation
+ * Copyright (C) 2009 EF Johnson Technologies
+ *
+ * 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
+ */
+
+#include <linux/kernel.h>
+#include <linux/device.h>
+#include <linux/etherdevice.h>
+#include <linux/crc32.h>
+
+#include "u_ether.h"
+
+#define EEM_HLEN 2
+
+/*
+ * This function is a "CDC Ethernet Emulation Model" (CDC EEM)
+ * Ethernet link.
+ */
+
+struct eem_ep_descs {
+	struct usb_endpoint_descriptor	*in;
+	struct usb_endpoint_descriptor	*out;
+};
+
+struct f_eem {
+	struct gether			port;
+	u8				ctrl_id;
+
+	struct eem_ep_descs		fs;
+	struct eem_ep_descs		hs;
+};
+
+static inline struct f_eem *func_to_eem(struct usb_function *f)
+{
+	return container_of(f, struct f_eem, port.func);
+}
+
+/*-------------------------------------------------------------------------*/
+
+/* interface descriptor: */
+
+static struct usb_interface_descriptor eem_intf __initdata = {
+	.bLength =		sizeof eem_intf,
+	.bDescriptorType =	USB_DT_INTERFACE,
+
+	/* .bInterfaceNumber = DYNAMIC */
+	.bNumEndpoints =	2,
+	.bInterfaceClass =	USB_CLASS_COMM,
+	.bInterfaceSubClass =	USB_CDC_SUBCLASS_EEM,
+	.bInterfaceProtocol =	USB_CDC_PROTO_EEM,
+	/* .iInterface = DYNAMIC */
+};
+
+/* full speed support: */
+
+static struct usb_endpoint_descriptor eem_fs_in_desc __initdata = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bEndpointAddress =	USB_DIR_IN,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+};
+
+static struct usb_endpoint_descriptor eem_fs_out_desc __initdata = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bEndpointAddress =	USB_DIR_OUT,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+};
+
+static struct usb_descriptor_header *eem_fs_function[] __initdata = {
+	/* CDC EEM control descriptors */
+	(struct usb_descriptor_header *) &eem_intf,
+	(struct usb_descriptor_header *) &eem_fs_in_desc,
+	(struct usb_descriptor_header *) &eem_fs_out_desc,
+	NULL,
+};
+
+/* high speed support: */
+
+static struct usb_endpoint_descriptor eem_hs_in_desc __initdata = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bEndpointAddress =	USB_DIR_IN,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+	.wMaxPacketSize =	cpu_to_le16(512),
+};
+
+static struct usb_endpoint_descriptor eem_hs_out_desc __initdata = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bEndpointAddress =	USB_DIR_OUT,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+	.wMaxPacketSize =	cpu_to_le16(512),
+};
+
+static struct usb_descriptor_header *eem_hs_function[] __initdata = {
+	/* CDC EEM control descriptors */
+	(struct usb_descriptor_header *) &eem_intf,
+	(struct usb_descriptor_header *) &eem_hs_in_desc,
+	(struct usb_descriptor_header *) &eem_hs_out_desc,
+	NULL,
+};
+
+/* string descriptors: */
+
+static struct usb_string eem_string_defs[] = {
+	[0].s = "CDC Ethernet Emulation Model (EEM)",
+	{  } /* end of list */
+};
+
+static struct usb_gadget_strings eem_string_table = {
+	.language =		0x0409,	/* en-us */
+	.strings =		eem_string_defs,
+};
+
+static struct usb_gadget_strings *eem_strings[] = {
+	&eem_string_table,
+	NULL,
+};
+
+/*-------------------------------------------------------------------------*/
+
+static int eem_setup(struct usb_function *f, const struct usb_ctrlrequest *ctrl)
+{
+	struct usb_composite_dev *cdev = f->config->cdev;
+	int			value = -EOPNOTSUPP;
+	u16			w_index = le16_to_cpu(ctrl->wIndex);
+	u16			w_value = le16_to_cpu(ctrl->wValue);
+	u16			w_length = le16_to_cpu(ctrl->wLength);
+
+	DBG(cdev, "invalid control req%02x.%02x v%04x i%04x l%d\n",
+		ctrl->bRequestType, ctrl->bRequest,
+		w_value, w_index, w_length);
+
+	/* device either stalls (value < 0) or reports success */
+	return value;
+}
+
+
+static int eem_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
+{
+	struct f_eem		*eem = func_to_eem(f);
+	struct usb_composite_dev *cdev = f->config->cdev;
+	struct net_device	*net;
+
+	/* we know alt == 0, so this is an activation or a reset */
+	if (alt != 0)
+		goto fail;
+
+	if (intf == eem->ctrl_id) {
+
+		if (eem->port.in_ep->driver_data) {
+			DBG(cdev, "reset eem\n");
+			gether_disconnect(&eem->port);
+		}
+
+		if (!eem->port.in) {
+			DBG(cdev, "init eem\n");
+			eem->port.in = ep_choose(cdev->gadget,
+					eem->hs.in, eem->fs.in);
+			eem->port.out = ep_choose(cdev->gadget,
+					eem->hs.out, eem->fs.out);
+		}
+
+		/* zlps should not occur because zero-length EEM packets
+		 * will be inserted in those cases where they would occur
+		 */
+		eem->port.is_zlp_ok = 1;
+		eem->port.cdc_filter = DEFAULT_FILTER;
+		DBG(cdev, "activate eem\n");
+		net = gether_connect(&eem->port);
+		if (IS_ERR(net))
+			return PTR_ERR(net);
+	} else
+		goto fail;
+
+	return 0;
+fail:
+	return -EINVAL;
+}
+
+static void eem_disable(struct usb_function *f)
+{
+	struct f_eem		*eem = func_to_eem(f);
+	struct usb_composite_dev *cdev = f->config->cdev;
+
+	DBG(cdev, "eem deactivated\n");
+
+	if (eem->port.in_ep->driver_data)
+		gether_disconnect(&eem->port);
+}
+
+/*-------------------------------------------------------------------------*/
+
+/* EEM function driver setup/binding */
+
+static int __init
+eem_bind(struct usb_configuration *c, struct usb_function *f)
+{
+	struct usb_composite_dev *cdev = c->cdev;
+	struct f_eem		*eem = func_to_eem(f);
+	int			status;
+	struct usb_ep		*ep;
+
+	/* allocate instance-specific interface IDs */
+	status = usb_interface_id(c, f);
+	if (status < 0)
+		goto fail;
+	eem->ctrl_id = status;
+	eem_intf.bInterfaceNumber = status;
+
+	status = -ENODEV;
+
+	/* allocate instance-specific endpoints */
+	ep = usb_ep_autoconfig(cdev->gadget, &eem_fs_in_desc);
+	if (!ep)
+		goto fail;
+	eem->port.in_ep = ep;
+	ep->driver_data = cdev;	/* claim */
+
+	ep = usb_ep_autoconfig(cdev->gadget, &eem_fs_out_desc);
+	if (!ep)
+		goto fail;
+	eem->port.out_ep = ep;
+	ep->driver_data = cdev;	/* claim */
+
+	status = -ENOMEM;
+
+	/* copy descriptors, and track endpoint copies */
+	f->descriptors = usb_copy_descriptors(eem_fs_function);
+	if (!f->descriptors)
+		goto fail;
+
+	eem->fs.in = usb_find_endpoint(eem_fs_function,
+			f->descriptors, &eem_fs_in_desc);
+	eem->fs.out = usb_find_endpoint(eem_fs_function,
+			f->descriptors, &eem_fs_out_desc);
+
+	/* support all relevant hardware speeds... we expect that when
+	 * hardware is dual speed, all bulk-capable endpoints work at
+	 * both speeds
+	 */
+	if (gadget_is_dualspeed(c->cdev->gadget)) {
+		eem_hs_in_desc.bEndpointAddress =
+				eem_fs_in_desc.bEndpointAddress;
+		eem_hs_out_desc.bEndpointAddress =
+				eem_fs_out_desc.bEndpointAddress;
+
+		/* copy descriptors, and track endpoint copies */
+		f->hs_descriptors = usb_copy_descriptors(eem_hs_function);
+		if (!f->hs_descriptors)
+			goto fail;
+
+		eem->hs.in = usb_find_endpoint(eem_hs_function,
+				f->hs_descriptors, &eem_hs_in_desc);
+		eem->hs.out = usb_find_endpoint(eem_hs_function,
+				f->hs_descriptors, &eem_hs_out_desc);
+	}
+
+	DBG(cdev, "CDC Ethernet (EEM): %s speed IN/%s OUT/%s\n",
+			gadget_is_dualspeed(c->cdev->gadget) ? "dual" : "full",
+			eem->port.in_ep->name, eem->port.out_ep->name);
+	return 0;
+
+fail:
+	if (f->descriptors)
+		usb_free_descriptors(f->descriptors);
+
+	/* we might as well release our claims on endpoints */
+	if (eem->port.out)
+		eem->port.out_ep->driver_data = NULL;
+	if (eem->port.in)
+		eem->port.in_ep->driver_data = NULL;
+
+	ERROR(cdev, "%s: can't bind, err %d\n", f->name, status);
+
+	return status;
+}
+
+static void
+eem_unbind(struct usb_configuration *c, struct usb_function *f)
+{
+	struct f_eem	*eem = func_to_eem(f);
+
+	DBG(c->cdev, "eem unbind\n");
+
+	if (gadget_is_dualspeed(c->cdev->gadget))
+		usb_free_descriptors(f->hs_descriptors);
+	usb_free_descriptors(f->descriptors);
+	kfree(eem);
+}
+
+static void eem_cmd_complete(struct usb_ep *ep, struct usb_request *req)
+{
+}
+
+/*
+ * Add the EEM header and ethernet checksum.
+ * We currently do not attempt to put multiple ethernet frames
+ * into a single USB transfer
+ */
+static struct sk_buff *eem_wrap(struct gether *port, struct sk_buff *skb)
+{
+	struct sk_buff	*skb2 = NULL;
+	struct usb_ep	*in = port->in_ep;
+	int		padlen = 0;
+	u16		len = skb->len;
+
+	if (!skb_cloned(skb)) {
+		int headroom = skb_headroom(skb);
+		int tailroom = skb_tailroom(skb);
+
+		/* When (len + EEM_HLEN + ETH_FCS_LEN) % in->maxpacket) is 0,
+		 * stick two bytes of zero-length EEM packet on the end.
+		 */
+		if (((len + EEM_HLEN + ETH_FCS_LEN) % in->maxpacket) == 0)
+			padlen += 2;
+
+		if ((tailroom >= (ETH_FCS_LEN + padlen)) &&
+				(headroom >= EEM_HLEN))
+			goto done;
+	}
+
+	skb2 = skb_copy_expand(skb, EEM_HLEN, ETH_FCS_LEN + padlen, GFP_ATOMIC);
+	dev_kfree_skb_any(skb);
+	skb = skb2;
+	if (!skb)
+		return skb;
+
+done:
+	/* use the "no CRC" option */
+	put_unaligned_be32(0xdeadbeef, skb_put(skb, 4));
+
+	/* EEM packet header format:
+	 * b0..13:	length of ethernet frame
+	 * b14:		bmCRC (0 == sentinel CRC)
+	 * b15:		bmType (0 == data)
+	 */
+	len = skb->len;
+	put_unaligned_le16((len & 0x3FFF) | BIT(14), skb_push(skb, 2));
+
+	/* add a zero-length EEM packet, if needed */
+	if (padlen)
+		put_unaligned_le16(0, skb_put(skb, 2));
+
+	return skb;
+}
+
+/*
+ * Remove the EEM header.  Note that there can be many EEM packets in a single
+ * USB transfer, so we need to break them out and handle them independently.
+ */
+static int eem_unwrap(struct gether *port,
+			struct sk_buff *skb,
+			struct sk_buff_head *list)
+{
+	struct usb_composite_dev	*cdev = port->func.config->cdev;
+	int				status = 0;
+
+	do {
+		struct sk_buff	*skb2;
+		u16		header;
+		u16		len = 0;
+
+		if (skb->len < EEM_HLEN) {
+			status = -EINVAL;
+			DBG(cdev, "invalid EEM header\n");
+			goto error;
+		}
+
+		/* remove the EEM header */
+		header = get_unaligned_le16(skb->data);
+		skb_pull(skb, EEM_HLEN);
+
+		/* EEM packet header format:
+		 * b0..14:	EEM type dependent (data or command)
+		 * b15:		bmType (0 == data, 1 == command)
+		 */
+		if (header & BIT(15)) {
+			struct usb_request	*req = cdev->req;
+			u16			bmEEMCmd;
+
+			/* EEM command packet format:
+			 * b0..10:	bmEEMCmdParam
+			 * b11..13:	bmEEMCmd
+			 * b14:		reserved (must be zero)
+			 * b15:		bmType (1 == command)
+			 */
+			if (header & BIT(14))
+				continue;
+
+			bmEEMCmd = (header >> 11) & 0x7;
+			switch (bmEEMCmd) {
+			case 0: /* echo */
+				len = header & 0x7FF;
+				if (skb->len < len) {
+					status = -EOVERFLOW;
+					goto error;
+				}
+
+				skb2 = skb_clone(skb, GFP_ATOMIC);
+				if (unlikely(!skb2)) {
+					DBG(cdev, "EEM echo response error\n");
+					goto next;
+				}
+				skb_trim(skb2, len);
+				put_unaligned_le16(BIT(15) | BIT(11) | len,
+							skb_push(skb2, 2));
+				skb_copy_bits(skb, 0, req->buf, skb->len);
+				req->length = skb->len;
+				req->complete = eem_cmd_complete;
+				req->zero = 1;
+				if (usb_ep_queue(port->in_ep, req, GFP_ATOMIC))
+					DBG(cdev, "echo response queue fail\n");
+				break;
+
+			case 1:  /* echo response */
+			case 2:  /* suspend hint */
+			case 3:  /* response hint */
+			case 4:  /* response complete hint */
+			case 5:  /* tickle */
+			default: /* reserved */
+				continue;
+			}
+		} else {
+			u32		crc, crc2;
+			struct sk_buff	*skb3;
+
+			/* check for zero-length EEM packet */
+			if (header == 0)
+				continue;
+
+			/* EEM data packet format:
+			 * b0..13:	length of ethernet frame
+			 * b14:		bmCRC (0 == sentinel, 1 == calculated)
+			 * b15:		bmType (0 == data)
+			 */
+			len = header & 0x3FFF;
+			if ((skb->len < len)
+					|| (len < (ETH_HLEN + ETH_FCS_LEN))) {
+				status = -EINVAL;
+				goto error;
+			}
+
+			/* validate CRC */
+			crc = get_unaligned_le32(skb->data + len - ETH_FCS_LEN);
+			if (header & BIT(14)) {
+				crc = get_unaligned_le32(skb->data + len
+							- ETH_FCS_LEN);
+				crc2 = ~crc32_le(~0,
+						skb->data,
+						skb->len - ETH_FCS_LEN);
+			} else {
+				crc = get_unaligned_be32(skb->data + len
+							- ETH_FCS_LEN);
+				crc2 = 0xdeadbeef;
+			}
+			if (crc != crc2) {
+				DBG(cdev, "invalid EEM CRC\n");
+				goto next;
+			}
+
+			skb2 = skb_clone(skb, GFP_ATOMIC);
+			if (unlikely(!skb2)) {
+				DBG(cdev, "unable to unframe EEM packet\n");
+				continue;
+			}
+			skb_trim(skb2, len - ETH_FCS_LEN);
+
+			skb3 = skb_copy_expand(skb2,
+						NET_IP_ALIGN,
+						0,
+						GFP_ATOMIC);
+			if (unlikely(!skb3)) {
+				DBG(cdev, "unable to realign EEM packet\n");
+				dev_kfree_skb_any(skb2);
+				continue;
+			}
+			dev_kfree_skb_any(skb2);
+			skb_queue_tail(list, skb3);
+		}
+next:
+		skb_pull(skb, len);
+	} while (skb->len);
+
+error:
+	dev_kfree_skb_any(skb);
+	return status;
+}
+
+/**
+ * eem_bind_config - add CDC Ethernet (EEM) network link to a configuration
+ * @c: the configuration to support the network link
+ * Context: single threaded during gadget setup
+ *
+ * Returns zero on success, else negative errno.
+ *
+ * Caller must have called @gether_setup().  Caller is also responsible
+ * for calling @gether_cleanup() before module unload.
+ */
+int __init eem_bind_config(struct usb_configuration *c)
+{
+	struct f_eem	*eem;
+	int		status;
+
+	/* maybe allocate device-global string IDs */
+	if (eem_string_defs[0].id == 0) {
+
+		/* control interface label */
+		status = usb_string_id(c->cdev);
+		if (status < 0)
+			return status;
+		eem_string_defs[0].id = status;
+		eem_intf.iInterface = status;
+	}
+
+	/* allocate and initialize one new instance */
+	eem = kzalloc(sizeof *eem, GFP_KERNEL);
+	if (!eem)
+		return -ENOMEM;
+
+	eem->port.cdc_filter = DEFAULT_FILTER;
+
+	eem->port.func.name = "cdc_eem";
+	eem->port.func.strings = eem_strings;
+	/* descriptors are per-instance copies */
+	eem->port.func.bind = eem_bind;
+	eem->port.func.unbind = eem_unbind;
+	eem->port.func.set_alt = eem_set_alt;
+	eem->port.func.setup = eem_setup;
+	eem->port.func.disable = eem_disable;
+	eem->port.wrap = eem_wrap;
+	eem->port.unwrap = eem_unwrap;
+	eem->port.header_len = EEM_HLEN;
+
+	status = usb_add_function(c, &eem->port.func);
+	if (status)
+		kfree(eem);
+	return status;
+}
+