usb: net: introduce support for Moschip USB ethernet

introduce an 'mcs7830' driver for Moschip MCS7830 based (7730/7830/7832)
USB 2.0 Ethernet Devices

see "MCS7830 -- USB 2.0 to 10/100M Fast Ethernet Controller" at
http://www.asix.com.tw/products.php?op=pItemdetail&PItemID=109;74;109

the driver was implemented based on the U-Boot Asix driver with
additional information gathered from the Moschip Linux driver,
development was done on "Delock 61147" and "Logilink UA0025C" dongles

Signed-off-by: Gerhard Sittig <gsi@denx.de>
Acked-by: Marek Vasut <marex@denx.de>

1 files changed, 812 insertions, 0 deletions

diff --git a/drivers/usb/eth/mcs7830.c b/drivers/usb/eth/mcs7830.c
new file mode 100644
index 0000000..c353286
--- /dev/null
+++ b/drivers/usb/eth/mcs7830.c
@@ -0,0 +1,812 @@
+/*
+ * Copyright (c) 2013 Gerhard Sittig <gsi@denx.de>
+ * based on the U-Boot Asix driver as well as information
+ * from the Linux Moschip driver
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+/*
+ * MOSCHIP MCS7830 based (7730/7830/7832) USB 2.0 Ethernet Devices
+ */
+
+#include <common.h>
+#include <errno.h>
+#include <linux/mii.h>
+#include <malloc.h>
+#include <usb.h>
+
+#include "usb_ether.h"
+
+#define MCS7830_BASE_NAME	"mcs"
+
+#define USBCALL_TIMEOUT		1000
+#define LINKSTATUS_TIMEOUT	5000	/* link status, connect timeout */
+#define LINKSTATUS_TIMEOUT_RES	50	/* link status, resolution in msec */
+
+#define MCS7830_RX_URB_SIZE	2048
+
+/* command opcodes */
+#define MCS7830_WR_BREQ		0x0d
+#define MCS7830_RD_BREQ		0x0e
+
+/* register layout, numerical offset specs for USB API calls */
+struct mcs7830_regs {
+	uint8_t multicast_hashes[8];
+	uint8_t packet_gap[2];
+	uint8_t phy_data[2];
+	uint8_t phy_command[2];
+	uint8_t configuration;
+	uint8_t ether_address[6];
+	uint8_t frame_drop_count;
+	uint8_t pause_threshold;
+};
+#define REG_MULTICAST_HASH	offsetof(struct mcs7830_regs, multicast_hashes)
+#define REG_PHY_DATA		offsetof(struct mcs7830_regs, phy_data)
+#define REG_PHY_CMD		offsetof(struct mcs7830_regs, phy_command)
+#define REG_CONFIG		offsetof(struct mcs7830_regs, configuration)
+#define REG_ETHER_ADDR		offsetof(struct mcs7830_regs, ether_address)
+#define REG_FRAME_DROP_COUNTER	offsetof(struct mcs7830_regs, frame_drop_count)
+#define REG_PAUSE_THRESHOLD	offsetof(struct mcs7830_regs, pause_threshold)
+
+/* bit masks and default values for the above registers */
+#define PHY_CMD1_READ		0x40
+#define PHY_CMD1_WRITE		0x20
+#define PHY_CMD1_PHYADDR	0x01
+
+#define PHY_CMD2_PEND		0x80
+#define PHY_CMD2_READY		0x40
+
+#define CONF_CFG		0x80
+#define CONF_SPEED100		0x40
+#define CONF_FDX_ENABLE		0x20
+#define CONF_RXENABLE		0x10
+#define CONF_TXENABLE		0x08
+#define CONF_SLEEPMODE		0x04
+#define CONF_ALLMULTICAST	0x02
+#define CONF_PROMISCUOUS	0x01
+
+#define PAUSE_THRESHOLD_DEFAULT	0
+
+/* bit masks for the status byte which follows received ethernet frames */
+#define STAT_RX_FRAME_CORRECT	0x20
+#define STAT_RX_LARGE_FRAME	0x10
+#define STAT_RX_CRC_ERROR	0x08
+#define STAT_RX_ALIGNMENT_ERROR	0x04
+#define STAT_RX_LENGTH_ERROR	0x02
+#define STAT_RX_SHORT_FRAME	0x01
+
+/*
+ * struct mcs7830_private - private driver data for an individual adapter
+ * @config:	shadow for the network adapter's configuration register
+ * @mchash:	shadow for the network adapter's multicast hash registers
+ */
+struct mcs7830_private {
+	uint8_t config;
+	uint8_t mchash[8];
+};
+
+/*
+ * mcs7830_read_reg() - read a register of the network adapter
+ * @dev:	network device to read from
+ * @idx:	index of the register to start reading from
+ * @size:	number of bytes to read
+ * @data:	buffer to read into
+ * Return: zero upon success, negative upon error
+ */
+static int mcs7830_read_reg(struct ueth_data *dev, uint8_t idx,
+			    uint16_t size, void *data)
+{
+	int len;
+	ALLOC_CACHE_ALIGN_BUFFER(uint8_t, buf, size);
+
+	debug("%s() idx=0x%04X sz=%d\n", __func__, idx, size);
+
+	len = usb_control_msg(dev->pusb_dev,
+			      usb_rcvctrlpipe(dev->pusb_dev, 0),
+			      MCS7830_RD_BREQ,
+			      USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
+			      0, idx, buf, size,
+			      USBCALL_TIMEOUT);
+	if (len != size) {
+		debug("%s() len=%d != sz=%d\n", __func__, len, size);
+		return -EIO;
+	}
+	memcpy(data, buf, size);
+	return 0;
+}
+
+/*
+ * mcs7830_write_reg() - write a register of the network adapter
+ * @dev:	network device to write to
+ * @idx:	index of the register to start writing to
+ * @size:	number of bytes to write
+ * @data:	buffer holding the data to write
+ * Return: zero upon success, negative upon error
+ */
+static int mcs7830_write_reg(struct ueth_data *dev, uint8_t idx,
+			     uint16_t size, void *data)
+{
+	int len;
+	ALLOC_CACHE_ALIGN_BUFFER(uint8_t, buf, size);
+
+	debug("%s() idx=0x%04X sz=%d\n", __func__, idx, size);
+
+	memcpy(buf, data, size);
+	len = usb_control_msg(dev->pusb_dev,
+			      usb_sndctrlpipe(dev->pusb_dev, 0),
+			      MCS7830_WR_BREQ,
+			      USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
+			      0, idx, buf, size,
+			      USBCALL_TIMEOUT);
+	if (len != size) {
+		debug("%s() len=%d != sz=%d\n", __func__, len, size);
+		return -EIO;
+	}
+	return 0;
+}
+
+/*
+ * mcs7830_phy_emit_wait() - emit PHY read/write access, wait for its execution
+ * @dev:	network device to talk to
+ * @rwflag:	PHY_CMD1_READ or PHY_CMD1_WRITE opcode
+ * @index:	number of the PHY register to read or write
+ * Return: zero upon success, negative upon error
+ */
+static int mcs7830_phy_emit_wait(struct ueth_data *dev,
+				 uint8_t rwflag, uint8_t index)
+{
+	int rc;
+	int retry;
+	uint8_t cmd[2];
+
+	/* send the PHY read/write request */
+	cmd[0] = rwflag | PHY_CMD1_PHYADDR;
+	cmd[1] = PHY_CMD2_PEND | (index & 0x1f);
+	rc = mcs7830_write_reg(dev, REG_PHY_CMD, sizeof(cmd), cmd);
+	if (rc < 0)
+		return rc;
+
+	/* wait for the response to become available (usually < 1ms) */
+	retry = 10;
+	do {
+		rc = mcs7830_read_reg(dev, REG_PHY_CMD, sizeof(cmd), cmd);
+		if (rc < 0)
+			return rc;
+		if (cmd[1] & PHY_CMD2_READY)
+			return 0;
+		if (!retry--)
+			return -ETIMEDOUT;
+		mdelay(1);
+	} while (1);
+	/* UNREACH */
+}
+
+/*
+ * mcs7830_read_phy() - read a PHY register of the network adapter
+ * @dev:	network device to read from
+ * @index:	index of the PHY register to read from
+ * Return: non-negative 16bit register content, negative upon error
+ */
+static int mcs7830_read_phy(struct ueth_data *dev, uint8_t index)
+{
+	int rc;
+	uint16_t val;
+
+	/* issue the PHY read request and wait for its execution */
+	rc = mcs7830_phy_emit_wait(dev, PHY_CMD1_READ, index);
+	if (rc < 0)
+		return rc;
+
+	/* fetch the PHY data which was read */
+	rc = mcs7830_read_reg(dev, REG_PHY_DATA, sizeof(val), &val);
+	if (rc < 0)
+		return rc;
+	rc = le16_to_cpu(val);
+	debug("%s(%s, %d) => 0x%04X\n", __func__, dev->eth_dev.name, index, rc);
+	return rc;
+}
+
+/*
+ * mcs7830_write_phy() - write a PHY register of the network adapter
+ * @dev:	network device to write to
+ * @index:	index of the PHY register to write to
+ * @val:	value to write to the PHY register
+ * Return: zero upon success, negative upon error
+ */
+static int mcs7830_write_phy(struct ueth_data *dev, uint8_t index, uint16_t val)
+{
+	int rc;
+
+	debug("%s(%s, %d, 0x%04X)\n", __func__, dev->eth_dev.name, index, val);
+
+	/* setup the PHY data which is to get written */
+	val = cpu_to_le16(val);
+	rc = mcs7830_write_reg(dev, REG_PHY_DATA, sizeof(val), &val);
+	if (rc < 0)
+		return rc;
+
+	/* issue the PHY write request and wait for its execution */
+	rc = mcs7830_phy_emit_wait(dev, PHY_CMD1_WRITE, index);
+	if (rc < 0)
+		return rc;
+
+	return 0;
+}
+
+/*
+ * mcs7830_write_config() - write to the network adapter's config register
+ * @eth:	network device to write to
+ * Return: zero upon success, negative upon error
+ *
+ * the data which gets written is taken from the shadow config register
+ * within the device driver's private data
+ */
+static int mcs7830_write_config(struct ueth_data *dev)
+{
+	struct mcs7830_private *priv;
+	int rc;
+
+	debug("%s()\n", __func__);
+	priv = dev->dev_priv;
+
+	rc = mcs7830_write_reg(dev, REG_CONFIG,
+			       sizeof(priv->config), &priv->config);
+	if (rc < 0) {
+		debug("writing config to adapter failed\n");
+		return rc;
+	}
+
+	return 0;
+}
+
+/*
+ * mcs7830_write_mchash() - write the network adapter's multicast filter
+ * @eth:	network device to write to
+ * Return: zero upon success, negative upon error
+ *
+ * the data which gets written is taken from the shadow multicast hashes
+ * within the device driver's private data
+ */
+static int mcs7830_write_mchash(struct ueth_data *dev)
+{
+	struct mcs7830_private *priv;
+	int rc;
+
+	debug("%s()\n", __func__);
+	priv = dev->dev_priv;
+
+	rc = mcs7830_write_reg(dev, REG_MULTICAST_HASH,
+			       sizeof(priv->mchash), &priv->mchash);
+	if (rc < 0) {
+		debug("writing multicast hash to adapter failed\n");
+		return rc;
+	}
+
+	return 0;
+}
+
+/*
+ * mcs7830_set_autoneg() - setup and trigger ethernet link autonegotiation
+ * @eth:	network device to run link negotiation on
+ * Return: zero upon success, negative upon error
+ *
+ * the routine advertises available media and starts autonegotiation
+ */
+static int mcs7830_set_autoneg(struct ueth_data *dev)
+{
+	int adv, flg;
+	int rc;
+
+	debug("%s()\n", __func__);
+
+	/*
+	 * algorithm taken from the Linux driver, which took it from
+	 * "the original mcs7830 version 1.4 driver":
+	 *
+	 * enable all media, reset BMCR, enable auto neg, restart
+	 * auto neg while keeping the enable auto neg flag set
+	 */
+
+	adv = ADVERTISE_PAUSE_CAP | ADVERTISE_ALL | ADVERTISE_CSMA;
+	rc = mcs7830_write_phy(dev, MII_ADVERTISE, adv);
+
+	flg = 0;
+	if (!rc)
+		rc = mcs7830_write_phy(dev, MII_BMCR, flg);
+
+	flg |= BMCR_ANENABLE;
+	if (!rc)
+		rc = mcs7830_write_phy(dev, MII_BMCR, flg);
+
+	flg |= BMCR_ANRESTART;
+	if (!rc)
+		rc = mcs7830_write_phy(dev, MII_BMCR, flg);
+
+	return rc;
+}
+
+/*
+ * mcs7830_get_rev() - identify a network adapter's chip revision
+ * @eth:	network device to identify
+ * Return: non-negative number, reflecting the revision number
+ *
+ * currently, only "rev C and higher" and "below rev C" are needed, so
+ * the return value is #1 for "below rev C", and #2 for "rev C and above"
+ */
+static int mcs7830_get_rev(struct ueth_data *dev)
+{
+	uint8_t buf[2];
+	int rc;
+	int rev;
+
+	/* register 22 is readable in rev C and higher */
+	rc = mcs7830_read_reg(dev, REG_FRAME_DROP_COUNTER, sizeof(buf), buf);
+	if (rc < 0)
+		rev = 1;
+	else
+		rev = 2;
+	debug("%s() rc=%d, rev=%d\n", __func__, rc, rev);
+	return rev;
+}
+
+/*
+ * mcs7830_apply_fixup() - identify an adapter and potentially apply fixups
+ * @eth:	network device to identify and apply fixups to
+ * Return: zero upon success (no errors emitted from here)
+ *
+ * this routine identifies the network adapter's chip revision, and applies
+ * fixups for known issues
+ */
+static int mcs7830_apply_fixup(struct ueth_data *dev)
+{
+	int rev;
+	int i;
+	uint8_t thr;
+
+	rev = mcs7830_get_rev(dev);
+	debug("%s() rev=%d\n", __func__, rev);
+
+	/*
+	 * rev C requires setting the pause threshold (the Linux driver
+	 * is inconsistent, the implementation does it for "rev C
+	 * exactly", the introductory comment says "rev C and above")
+	 */
+	if (rev == 2) {
+		debug("%s: applying rev C fixup\n", dev->eth_dev.name);
+		thr = PAUSE_THRESHOLD_DEFAULT;
+		for (i = 0; i < 2; i++) {
+			(void)mcs7830_write_reg(dev, REG_PAUSE_THRESHOLD,
+						sizeof(thr), &thr);
+			mdelay(1);
+		}
+	}
+
+	return 0;
+}
+
+/*
+ * mcs7830_basic_reset() - bring the network adapter into a known first state
+ * @eth:	network device to act upon
+ * Return: zero upon success, negative upon error
+ *
+ * this routine initializes the network adapter such that subsequent invocations
+ * of the interface callbacks can exchange ethernet frames; link negotiation is
+ * triggered from here already and continues in background
+ */
+static int mcs7830_basic_reset(struct ueth_data *dev)
+{
+	struct mcs7830_private *priv;
+	int rc;
+
+	debug("%s()\n", __func__);
+	priv = dev->dev_priv;
+
+	/*
+	 * comment from the respective Linux driver, which
+	 * unconditionally sets the ALLMULTICAST flag as well:
+	 * should not be needed, but does not work otherwise
+	 */
+	priv->config = CONF_TXENABLE;
+	priv->config |= CONF_ALLMULTICAST;
+
+	rc = mcs7830_set_autoneg(dev);
+	if (rc < 0) {
+		error("setting autoneg failed\n");
+		return rc;
+	}
+
+	rc = mcs7830_write_mchash(dev);
+	if (rc < 0) {
+		error("failed to set multicast hash\n");
+		return rc;
+	}
+
+	rc = mcs7830_write_config(dev);
+	if (rc < 0) {
+		error("failed to set configuration\n");
+		return rc;
+	}
+
+	rc = mcs7830_apply_fixup(dev);
+	if (rc < 0) {
+		error("fixup application failed\n");
+		return rc;
+	}
+
+	return 0;
+}
+
+/*
+ * mcs7830_read_mac() - read an ethernet adapter's MAC address
+ * @eth:	network device to read from
+ * Return: zero upon success, negative upon error
+ *
+ * this routine fetches the MAC address stored within the ethernet adapter,
+ * and stores it in the ethernet interface's data structure
+ */
+static int mcs7830_read_mac(struct eth_device *eth)
+{
+	struct ueth_data *dev;
+	int rc;
+	uint8_t buf[ETH_ALEN];
+
+	debug("%s()\n", __func__);
+	dev = eth->priv;
+
+	rc = mcs7830_read_reg(dev, REG_ETHER_ADDR, ETH_ALEN, buf);
+	if (rc < 0) {
+		debug("reading MAC from adapter failed\n");
+		return rc;
+	}
+
+	memcpy(&eth->enetaddr[0], buf, ETH_ALEN);
+	return 0;
+}
+
+/*
+ * mcs7830_write_mac() - write an ethernet adapter's MAC address
+ * @eth:	network device to write to
+ * Return: zero upon success, negative upon error
+ *
+ * this routine takes the MAC address from the ethernet interface's data
+ * structure, and writes it into the ethernet adapter such that subsequent
+ * exchange of ethernet frames uses this address
+ */
+static int mcs7830_write_mac(struct eth_device *eth)
+{
+	struct ueth_data *dev;
+	int rc;
+
+	debug("%s()\n", __func__);
+	dev = eth->priv;
+
+	if (sizeof(eth->enetaddr) != ETH_ALEN)
+		return -EINVAL;
+	rc = mcs7830_write_reg(dev, REG_ETHER_ADDR, ETH_ALEN, eth->enetaddr);
+	if (rc < 0) {
+		debug("writing MAC to adapter failed\n");
+		return rc;
+	}
+	return 0;
+}
+
+/*
+ * mcs7830_init() - network interface's init callback
+ * @eth:	network device to initialize
+ * @bd:		board information
+ * Return: zero upon success, negative upon error
+ *
+ * after initial setup during probe() and get_info(), this init() callback
+ * ensures that the link is up and subsequent send() and recv() calls can
+ * exchange ethernet frames
+ */
+static int mcs7830_init(struct eth_device *eth, bd_t *bd)
+{
+	struct ueth_data *dev;
+	int timeout;
+	int have_link;
+
+	debug("%s()\n", __func__);
+	dev = eth->priv;
+
+	timeout = 0;
+	do {
+		have_link = mcs7830_read_phy(dev, MII_BMSR) & BMSR_LSTATUS;
+		if (have_link)
+			break;
+		udelay(LINKSTATUS_TIMEOUT_RES * 1000);
+		timeout += LINKSTATUS_TIMEOUT_RES;
+	} while (timeout < LINKSTATUS_TIMEOUT);
+	if (!have_link) {
+		debug("ethernet link is down\n");
+		return -ETIMEDOUT;
+	}
+	return 0;
+}
+
+/*
+ * mcs7830_send() - network interface's send callback
+ * @eth:	network device to send the frame from
+ * @packet:	ethernet frame content
+ * @length:	ethernet frame length
+ * Return: zero upon success, negative upon error
+ *
+ * this routine send an ethernet frame out of the network interface
+ */
+static int mcs7830_send(struct eth_device *eth, void *packet, int length)
+{
+	struct ueth_data *dev;
+	int rc;
+	int gotlen;
+	/* there is a status byte after the ethernet frame */
+	ALLOC_CACHE_ALIGN_BUFFER(uint8_t, buf, PKTSIZE + sizeof(uint8_t));
+
+	dev = eth->priv;
+
+	memcpy(buf, packet, length);
+	rc = usb_bulk_msg(dev->pusb_dev,
+			  usb_sndbulkpipe(dev->pusb_dev, dev->ep_out),
+			  &buf[0], length, &gotlen,
+			  USBCALL_TIMEOUT);
+	debug("%s() TX want len %d, got len %d, rc %d\n",
+	      __func__, length, gotlen, rc);
+	return rc;
+}
+
+/*
+ * mcs7830_recv() - network interface's recv callback
+ * @eth:	network device to receive frames from
+ * Return: zero upon success, negative upon error
+ *
+ * this routine checks for available ethernet frames that the network
+ * interface might have received, and notifies the network stack
+ */
+static int mcs7830_recv(struct eth_device *eth)
+{
+	struct ueth_data *dev;
+	ALLOC_CACHE_ALIGN_BUFFER(uint8_t, buf, MCS7830_RX_URB_SIZE);
+	int rc, wantlen, gotlen;
+	uint8_t sts;
+
+	debug("%s()\n", __func__);
+	dev = eth->priv;
+
+	/* fetch input data from the adapter */
+	wantlen = MCS7830_RX_URB_SIZE;
+	rc = usb_bulk_msg(dev->pusb_dev,
+			  usb_rcvbulkpipe(dev->pusb_dev, dev->ep_in),
+			  &buf[0], wantlen, &gotlen,
+			  USBCALL_TIMEOUT);
+	debug("%s() RX want len %d, got len %d, rc %d\n",
+	      __func__, wantlen, gotlen, rc);
+	if (rc != 0) {
+		error("RX: failed to receive\n");
+		return rc;
+	}
+	if (gotlen > wantlen) {
+		error("RX: got too many bytes (%d)\n", gotlen);
+		return -EIO;
+	}
+
+	/*
+	 * the bulk message that we received from USB contains exactly
+	 * one ethernet frame and a trailing status byte
+	 */
+	if (gotlen < sizeof(sts))
+		return -EIO;
+	gotlen -= sizeof(sts);
+	sts = buf[gotlen];
+
+	if (sts == STAT_RX_FRAME_CORRECT) {
+		debug("%s() got a frame, len=%d\n", __func__, gotlen);
+		NetReceive(buf, gotlen);
+		return 0;
+	}
+
+	debug("RX: frame error (sts 0x%02X, %s %s %s %s %s)\n",
+	      sts,
+	      (sts & STAT_RX_LARGE_FRAME) ? "large" : "-",
+	      (sts & STAT_RX_LENGTH_ERROR) ?  "length" : "-",
+	      (sts & STAT_RX_SHORT_FRAME) ? "short" : "-",
+	      (sts & STAT_RX_CRC_ERROR) ? "crc" : "-",
+	      (sts & STAT_RX_ALIGNMENT_ERROR) ?  "align" : "-");
+	return -EIO;
+}
+
+/*
+ * mcs7830_halt() - network interface's halt callback
+ * @eth:	network device to cease operation of
+ * Return: none
+ *
+ * this routine is supposed to undo the effect of previous initialization and
+ * ethernet frames exchange; in this implementation it's a NOP
+ */
+static void mcs7830_halt(struct eth_device *eth)
+{
+	debug("%s()\n", __func__);
+}
+
+/*
+ * mcs7830_iface_idx - index of detected network interfaces
+ *
+ * this counter keeps track of identified supported interfaces,
+ * to assign unique names as more interfaces are found
+ */
+static int mcs7830_iface_idx;
+
+/*
+ * mcs7830_eth_before_probe() - network driver's before_probe callback
+ * Return: none
+ *
+ * this routine initializes driver's internal data in preparation of
+ * subsequent probe callbacks
+ */
+void mcs7830_eth_before_probe(void)
+{
+	mcs7830_iface_idx = 0;
+}
+
+/*
+ * struct mcs7830_dongle - description of a supported Moschip ethernet dongle
+ * @vendor:	16bit USB vendor identification
+ * @product:	16bit USB product identification
+ *
+ * this structure describes a supported USB ethernet dongle by means of the
+ * vendor and product codes found during USB enumeration; no flags are held
+ * here since all supported dongles have identical behaviour, and required
+ * fixups get determined at runtime, such that no manual configuration is
+ * needed
+ */
+struct mcs7830_dongle {
+	uint16_t vendor;
+	uint16_t product;
+};
+
+/*
+ * mcs7830_dongles - the list of supported Moschip based USB ethernet dongles
+ */
+static const struct mcs7830_dongle const mcs7830_dongles[] = {
+	{ 0x9710, 0x7832, },	/* Moschip 7832 */
+	{ 0x9710, 0x7830, },	/* Moschip 7830 */
+	{ 0x9710, 0x7730, },	/* Moschip 7730 */
+	{ 0x0df6, 0x0021, },	/* Sitecom LN 30 */
+};
+
+/*
+ * mcs7830_eth_probe() - network driver's probe callback
+ * @dev:	detected USB device to check
+ * @ifnum:	detected USB interface to check
+ * @ss:		USB ethernet data structure to fill in upon match
+ * Return: #1 upon match, #0 upon mismatch or error
+ *
+ * this routine checks whether the found USB device is supported by
+ * this ethernet driver, and upon match fills in the USB ethernet
+ * data structure which later is passed to the get_info callback
+ */
+int mcs7830_eth_probe(struct usb_device *dev, unsigned int ifnum,
+		      struct ueth_data *ss)
+{
+	struct usb_interface *iface;
+	struct usb_interface_descriptor *iface_desc;
+	int i;
+	struct mcs7830_private *priv;
+	int ep_in_found, ep_out_found, ep_intr_found;
+
+	debug("%s()\n", __func__);
+
+	/* iterate the list of supported dongles */
+	iface = &dev->config.if_desc[ifnum];
+	iface_desc = &iface->desc;
+	for (i = 0; i < ARRAY_SIZE(mcs7830_dongles); i++) {
+		if (dev->descriptor.idVendor == mcs7830_dongles[i].vendor &&
+		    dev->descriptor.idProduct == mcs7830_dongles[i].product)
+			break;
+	}
+	if (i == ARRAY_SIZE(mcs7830_dongles))
+		return 0;
+	debug("detected USB ethernet device: %04X:%04X\n",
+	      dev->descriptor.idVendor, dev->descriptor.idProduct);
+
+	/* fill in driver private data */
+	priv = calloc(1, sizeof(*priv));
+	if (!priv)
+		return 0;
+
+	/* fill in the ueth_data structure, attach private data */
+	memset(ss, 0, sizeof(*ss));
+	ss->ifnum = ifnum;
+	ss->pusb_dev = dev;
+	ss->subclass = iface_desc->bInterfaceSubClass;
+	ss->protocol = iface_desc->bInterfaceProtocol;
+	ss->dev_priv = priv;
+
+	/*
+	 * a minimum of three endpoints is expected: in (bulk),
+	 * out (bulk), and interrupt; ignore all others
+	 */
+	ep_in_found = ep_out_found = ep_intr_found = 0;
+	for (i = 0; i < iface_desc->bNumEndpoints; i++) {
+		uint8_t eptype, epaddr;
+		bool is_input;
+
+		eptype = iface->ep_desc[i].bmAttributes;
+		eptype &= USB_ENDPOINT_XFERTYPE_MASK;
+
+		epaddr = iface->ep_desc[i].bEndpointAddress;
+		is_input = epaddr & USB_DIR_IN;
+		epaddr &= USB_ENDPOINT_NUMBER_MASK;
+
+		if (eptype == USB_ENDPOINT_XFER_BULK) {
+			if (is_input && !ep_in_found) {
+				ss->ep_in = epaddr;
+				ep_in_found++;
+			}
+			if (!is_input && !ep_out_found) {
+				ss->ep_out = epaddr;
+				ep_out_found++;
+			}
+		}
+
+		if (eptype == USB_ENDPOINT_XFER_INT) {
+			if (is_input && !ep_intr_found) {
+				ss->ep_int = epaddr;
+				ss->irqinterval = iface->ep_desc[i].bInterval;
+				ep_intr_found++;
+			}
+		}
+	}
+	debug("endpoints: in %d, out %d, intr %d\n",
+	      ss->ep_in, ss->ep_out, ss->ep_int);
+
+	/* apply basic sanity checks */
+	if (usb_set_interface(dev, iface_desc->bInterfaceNumber, 0) ||
+	    !ss->ep_in || !ss->ep_out || !ss->ep_int) {
+		debug("device probe incomplete\n");
+		return 0;
+	}
+
+	dev->privptr = ss;
+	return 1;
+}
+
+/*
+ * mcs7830_eth_get_info() - network driver's get_info callback
+ * @dev:	detected USB device
+ * @ss:		USB ethernet data structure filled in at probe()
+ * @eth:	ethernet interface data structure to fill in
+ * Return: #1 upon success, #0 upon error
+ *
+ * this routine registers the mandatory init(), send(), recv(), and
+ * halt() callbacks with the ethernet interface, can register the
+ * optional write_hwaddr() callback with the ethernet interface,
+ * and initiates configuration of the interface such that subsequent
+ * calls to those callbacks results in network communication
+ */
+int mcs7830_eth_get_info(struct usb_device *dev, struct ueth_data *ss,
+			 struct eth_device *eth)
+{
+	debug("%s()\n", __func__);
+	if (!eth) {
+		debug("%s: missing parameter.\n", __func__);
+		return 0;
+	}
+
+	snprintf(eth->name, sizeof(eth->name), "%s%d",
+		 MCS7830_BASE_NAME, mcs7830_iface_idx++);
+	eth->init = mcs7830_init;
+	eth->send = mcs7830_send;
+	eth->recv = mcs7830_recv;
+	eth->halt = mcs7830_halt;
+	eth->write_hwaddr = mcs7830_write_mac;
+	eth->priv = ss;
+
+	if (mcs7830_basic_reset(ss))
+		return 0;
+
+	if (mcs7830_read_mac(eth))
+		return 0;
+	debug("MAC %pM\n", eth->enetaddr);
+
+	return 1;
+}