diff mbox

[U-Boot,v2,3/7] usb: eth: introduce support for Moschip USB ethernet

Message ID 1392665727-5734-4-git-send-email-gsi@denx.de
State Superseded
Delegated to: Marek Vasut
Headers show

Commit Message

Gerhard Sittig Feb. 17, 2014, 7:35 p.m. UTC
introduce an 'mcs7830' driver for Moschip based USB ethernet adapters,
which was implemented based on the U-Boot Asix driver with additional
information gathered from the Moschip Linux driver

Cc: Joe Hershberger <joe.hershberger@gmail.com>
Cc: Simon Glass <sjg@chromium.org>
Cc: Marek Vasut <marex@denx.de>
Signed-off-by: Gerhard Sittig <gsi@denx.de>
---
 drivers/usb/eth/Makefile    |    1 +
 drivers/usb/eth/mcs7830.c   |  850 +++++++++++++++++++++++++++++++++++++++++++
 drivers/usb/eth/usb_ether.c |    7 +
 include/usb_ether.h         |    6 +
 4 files changed, 864 insertions(+)
 create mode 100644 drivers/usb/eth/mcs7830.c

Comments

Marek Vasut Feb. 17, 2014, 8:57 p.m. UTC | #1
On Monday, February 17, 2014 at 08:35:23 PM, Gerhard Sittig wrote:

[...]

> +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;
> +
> +#ifdef DEBUG
> +	(void)mcs7830_read_config(eth);

So this is debug-only function? You might want to put the entire function into 
#ifdef DEBUG and then have an #else , where you define the function as an empty 
one. The GCC shall handle the rest then as well, but you won't have this ugly 
ifdef in a function.
[...]

Best regards,
Marek Vasut
Wolfgang Denk Feb. 17, 2014, 9:11 p.m. UTC | #2
Dear Gerhard,

In message <1392665727-5734-4-git-send-email-gsi@denx.de> you wrote:
> introduce an 'mcs7830' driver for Moschip based USB ethernet adapters,
> which was implemented based on the U-Boot Asix driver with additional
> information gathered from the Moschip Linux driver
...
> +/* bit masks and default values for the above registers */
> +#define PHY_CMD1_READ		BIT(6)
> +#define PHY_CMD1_WRITE		BIT(5)
> +#define PHY_CMD1_PHYADDR	BIT(0)
> +
> +#define PHY_CMD2_PEND		BIT(7)
> +#define PHY_CMD2_READY		BIT(6)
...

As mentioned in patch # 1, I object against the use of these
obfuscating BIT() macros.  Please do not use these; use plain
readable code, that leaves no ambiguities to the reader.


Best regards,

Wolfgang Denk
Marek Vasut Feb. 17, 2014, 9:22 p.m. UTC | #3
On Monday, February 17, 2014 at 10:11:17 PM, Wolfgang Denk wrote:
> Dear Gerhard,
> 
> In message <1392665727-5734-4-git-send-email-gsi@denx.de> you wrote:
> > introduce an 'mcs7830' driver for Moschip based USB ethernet adapters,
> > which was implemented based on the U-Boot Asix driver with additional
> > information gathered from the Moschip Linux driver
> 
> ...
> 
> > +/* bit masks and default values for the above registers */
> > +#define PHY_CMD1_READ		BIT(6)
> > +#define PHY_CMD1_WRITE		BIT(5)
> > +#define PHY_CMD1_PHYADDR	BIT(0)
> > +
> > +#define PHY_CMD2_PEND		BIT(7)
> > +#define PHY_CMD2_READY		BIT(6)
> 
> ...
> 
> As mentioned in patch # 1, I object against the use of these
> obfuscating BIT() macros.  Please do not use these; use plain
> readable code, that leaves no ambiguities to the reader.

Just to chime in real quick, Linux uses these 'BIT()' macros, but I personally 
have no hard feelings about them either way.

Best regards,
Marek Vasut
Wolfgang Denk Feb. 17, 2014, 10:41 p.m. UTC | #4
Dear Marek,

In message <201402172222.38911.marex@denx.de> you wrote:
>
> > > +#define PHY_CMD1_READ		BIT(6)
> > > +#define PHY_CMD1_WRITE		BIT(5)
> > > +#define PHY_CMD1_PHYADDR	BIT(0)
> > > +
> > > +#define PHY_CMD2_PEND		BIT(7)
> > > +#define PHY_CMD2_READY		BIT(6)
> > 
> > ...
> > 
> > As mentioned in patch # 1, I object against the use of these
> > obfuscating BIT() macros.  Please do not use these; use plain
> > readable code, that leaves no ambiguities to the reader.
> 
> Just to chime in real quick, Linux uses these 'BIT()' macros, but I personally 
> have no hard feelings about them either way.

Yes, certain developers have been using this style before.  This does
not make it any better.  Fact is, that I have no way to tell what the
code means.  BIT(0) can be expected to have any of the following
meanings: 0x01, 0x80, 0x8000, 0x80000000, ... So I always have to look
up the macro definition first, before I can unerstand it.  And then I
have to compute in my head what the number actually means.

Compare: BIT(6) or 0x40 - what is easier to write, to read, and to
understand?

You dump a register - either with the BDI, or with some printf().
You get 0x27051956.  Is BIT(17) set?  Is bit 0x00020000 set?
Which of these questions is easier to answer (even when you are sure
that this is on a system where bit no. 0 is the LSB)?

It's all about writing portable and maintainable code.  

Best regards,

Wolfgang Denk
Marek Vasut Feb. 18, 2014, 11:24 a.m. UTC | #5
Hello Wolfgang,

> Dear Marek,
> 
> In message <201402172222.38911.marex@denx.de> you wrote:
> > > > +#define PHY_CMD1_READ		BIT(6)
> > > > +#define PHY_CMD1_WRITE		BIT(5)
> > > > +#define PHY_CMD1_PHYADDR	BIT(0)
> > > > +
> > > > +#define PHY_CMD2_PEND		BIT(7)
> > > > +#define PHY_CMD2_READY		BIT(6)
> > > 
> > > ...
> > > 
> > > As mentioned in patch # 1, I object against the use of these
> > > obfuscating BIT() macros.  Please do not use these; use plain
> > > readable code, that leaves no ambiguities to the reader.
> > 
> > Just to chime in real quick, Linux uses these 'BIT()' macros, but I
> > personally have no hard feelings about them either way.
> 
> Yes, certain developers have been using this style before.  This does
> not make it any better.  Fact is, that I have no way to tell what the
> code means.  BIT(0) can be expected to have any of the following
> meanings: 0x01, 0x80, 0x8000, 0x80000000, ... So I always have to look
> up the macro definition first, before I can unerstand it.  And then I
> have to compute in my head what the number actually means.
> 
> Compare: BIT(6) or 0x40 - what is easier to write, to read, and to
> understand?

(1 << 6) is easier for me to read honestly, because then I can quickly 
crosscheck it with the datasheet.

> You dump a register - either with the BDI, or with some printf().
> You get 0x27051956.  Is BIT(17) set?  Is bit 0x00020000 set?
> Which of these questions is easier to answer (even when you are sure
> that this is on a system where bit no. 0 is the LSB)?

You have a point with the endianness here.

Best regards,
Marek Vasut
Gerhard Sittig Feb. 23, 2014, 8:16 p.m. UTC | #6
On Mon, Feb 17, 2014 at 21:57 +0100, Marek Vasut wrote:
> 
> On Monday, February 17, 2014 at 08:35:23 PM, Gerhard Sittig wrote:
> 
> [...]
> 
> > +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;
> > +
> > +#ifdef DEBUG
> > +	(void)mcs7830_read_config(eth);
> 
> So this is debug-only function? You might want to put the entire function into 
> #ifdef DEBUG and then have an #else , where you define the function as an empty 
> one. The GCC shall handle the rest then as well, but you won't have this ugly 
> ifdef in a function.

I thought about this for a while.

Usually you'd expect separate control and status registers in
hardware.  Where you write to control, and read back from status.
Here those two aspects appear to have been mixed into one
"config" register, and only in hindsight the reading became
unused.  It's not so much an intent, but more of a byproduct.

During development (before the driver became operational), I
could not tell whether I had to read-modify-write that config
register.  Following the Linux driver's approach, currently only
fixed values get written to the adapter and nothing gets read
back.

Later the shadow in the driver's private data was introduced,
such that "updates" neither need to read back what was written
before.  And since neither multicast nor promiscuous mode may
apply to bootloader operation, even those updates may never need
not occur.

In the meantime I'd even tend to support the removal of the
config register read routine.  Adding code "just in case" is a
programmer's sin that may not be acceptable in U-Boot, since the
cost outweights the benefit.

The current implementation (v3, with "maybe unused" decoration)
might be acceptable.  But should feedback suggest that v4 is
needed, I will remove that routine as well.


virtually yours
Gerhard Sittig
Marek Vasut Feb. 24, 2014, 5:48 p.m. UTC | #7
On Sunday, February 23, 2014 at 09:16:20 PM, Gerhard Sittig wrote:
> On Mon, Feb 17, 2014 at 21:57 +0100, Marek Vasut wrote:
> > On Monday, February 17, 2014 at 08:35:23 PM, Gerhard Sittig wrote:
> > 
> > [...]
> > 
> > > +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;
> > > +
> > > +#ifdef DEBUG
> > > +	(void)mcs7830_read_config(eth);
> > 
> > So this is debug-only function? You might want to put the entire function
> > into #ifdef DEBUG and then have an #else , where you define the function
> > as an empty one. The GCC shall handle the rest then as well, but you
> > won't have this ugly ifdef in a function.
> 
> I thought about this for a while.
> 
> Usually you'd expect separate control and status registers in
> hardware.  Where you write to control, and read back from status.
> Here those two aspects appear to have been mixed into one
> "config" register, and only in hindsight the reading became
> unused.  It's not so much an intent, but more of a byproduct.
> 
> During development (before the driver became operational), I
> could not tell whether I had to read-modify-write that config
> register.  Following the Linux driver's approach, currently only
> fixed values get written to the adapter and nothing gets read
> back.
> 
> Later the shadow in the driver's private data was introduced,
> such that "updates" neither need to read back what was written
> before.  And since neither multicast nor promiscuous mode may
> apply to bootloader operation, even those updates may never need
> not occur.
> 
> In the meantime I'd even tend to support the removal of the
> config register read routine.  Adding code "just in case" is a
> programmer's sin that may not be acceptable in U-Boot, since the
> cost outweights the benefit.
> 
> The current implementation (v3, with "maybe unused" decoration)
> might be acceptable.  But should feedback suggest that v4 is
> needed, I will remove that routine as well.

If you feel like removing the routine, then please remove it .

Best regards,
Marek Vasut
diff mbox

Patch

diff --git a/drivers/usb/eth/Makefile b/drivers/usb/eth/Makefile
index 03f54749f720..94551c4c0c9a 100644
--- a/drivers/usb/eth/Makefile
+++ b/drivers/usb/eth/Makefile
@@ -8,4 +8,5 @@  obj-$(CONFIG_USB_HOST_ETHER) += usb_ether.o
 ifdef CONFIG_USB_ETHER_ASIX
 obj-y += asix.o
 endif
+obj-$(CONFIG_USB_ETHER_MCS7830) += mcs7830.o
 obj-$(CONFIG_USB_ETHER_SMSC95XX) += smsc95xx.o
diff --git a/drivers/usb/eth/mcs7830.c b/drivers/usb/eth/mcs7830.c
new file mode 100644
index 000000000000..991e2ee8f424
--- /dev/null
+++ b/drivers/usb/eth/mcs7830.c
@@ -0,0 +1,850 @@ 
+/*
+ * 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		BIT(6)
+#define PHY_CMD1_WRITE		BIT(5)
+#define PHY_CMD1_PHYADDR	BIT(0)
+
+#define PHY_CMD2_PEND		BIT(7)
+#define PHY_CMD2_READY		BIT(6)
+
+#define CONF_CFG		BIT(7)
+#define CONF_SPEED100		BIT(6)
+#define CONF_FDX_ENABLE		BIT(5)
+#define CONF_RXENABLE		BIT(4)
+#define CONF_TXENABLE		BIT(3)
+#define CONF_SLEEPMODE		BIT(2)
+#define CONF_ALLMULTICAST	BIT(1)
+#define CONF_PROMISCUOUS	BIT(0)
+
+#define PAUSE_THRESHOLD_DEFAULT	0
+
+/* bit masks for the status byte which follows received ethernet frames */
+#define STAT_RX_FRAME_CORRECT	BIT(5)
+#define STAT_RX_LARGE_FRAME	BIT(4)
+#define STAT_RX_CRC_ERROR	BIT(3)
+#define STAT_RX_ALIGNMENT_ERROR	BIT(2)
+#define STAT_RX_LENGTH_ERROR	BIT(1)
+#define STAT_RX_SHORT_FRAME	BIT(0)
+
+/*
+ * 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;
+
+	/* send the PHY read request */
+	/* 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_read_config() - read the network adapter's config register
+ * @eth:	network device to read from
+ * Return: non-negative register content upon success, negative upon error
+ */
+static int __maybe_unused mcs7830_read_config(struct eth_device *eth)
+{
+	struct ueth_data *dev;
+	int rc;
+	uint8_t cfg;
+
+	debug("%s()\n", __func__);
+	dev = eth->priv;
+
+	rc = mcs7830_read_reg(dev, REG_CONFIG, sizeof(cfg), &cfg);
+	if (rc < 0) {
+		debug("reading config from adapter failed\n");
+		return rc;
+	}
+
+	debug("%s() reg=0x%02X [ %s %s %s %s %s %s %s %s ]\n",
+	      __func__, cfg,
+	      (cfg & CONF_CFG) ? "cfg" : "-",
+	      (cfg & CONF_SPEED100) ? "100" : "-",
+	      (cfg & CONF_FDX_ENABLE) ? "fdx" : "-",
+	      (cfg & CONF_RXENABLE) ? "rx" : "-",
+	      (cfg & CONF_TXENABLE) ? "tx" : "-",
+	      (cfg & CONF_SLEEPMODE) ? "sleep" : "-",
+	      (cfg & CONF_ALLMULTICAST) ? "multi" : "-",
+	      (cfg & CONF_PROMISCUOUS) ? "promisc" : "-");
+	return cfg;
+}
+
+/*
+ * 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;
+
+#ifdef DEBUG
+	(void)mcs7830_read_config(eth);
+#endif
+
+	if (mcs7830_read_mac(eth))
+		return 0;
+	debug("MAC %pM\n", eth->enetaddr);
+
+	return 1;
+}
diff --git a/drivers/usb/eth/usb_ether.c b/drivers/usb/eth/usb_ether.c
index 2c4126be3601..1dda54c2f116 100644
--- a/drivers/usb/eth/usb_ether.c
+++ b/drivers/usb/eth/usb_ether.c
@@ -30,6 +30,13 @@  static const struct usb_eth_prob_dev prob_dev[] = {
 		.get_info = asix_eth_get_info,
 	},
 #endif
+#ifdef CONFIG_USB_ETHER_MCS7830
+	{
+		.before_probe = mcs7830_eth_before_probe,
+		.probe = mcs7830_eth_probe,
+		.get_info = mcs7830_eth_get_info,
+	},
+#endif
 #ifdef CONFIG_USB_ETHER_SMSC95XX
 	{
 		.before_probe = smsc95xx_eth_before_probe,
diff --git a/include/usb_ether.h b/include/usb_ether.h
index 011ead7a364e..35700a21b59f 100644
--- a/include/usb_ether.h
+++ b/include/usb_ether.h
@@ -49,6 +49,12 @@  int asix_eth_probe(struct usb_device *dev, unsigned int ifnum,
 int asix_eth_get_info(struct usb_device *dev, struct ueth_data *ss,
 		      struct eth_device *eth);
 
+void mcs7830_eth_before_probe(void);
+int mcs7830_eth_probe(struct usb_device *dev, unsigned int ifnum,
+		      struct ueth_data *ss);
+int mcs7830_eth_get_info(struct usb_device *dev, struct ueth_data *ss,
+			 struct eth_device *eth);
+
 void smsc95xx_eth_before_probe(void);
 int smsc95xx_eth_probe(struct usb_device *dev, unsigned int ifnum,
 			struct ueth_data *ss);