diff --git a/drivers/hid/Kconfig b/drivers/hid/Kconfig
index f722001..5eaf0db 100644
--- a/drivers/hid/Kconfig
+++ b/drivers/hid/Kconfig
@@ -175,6 +175,15 @@
 	  multimedia keyboard, but will lack support for the musical keyboard
 	  and some additional multimedia keys.
 
+config HID_CP2112
+	tristate "Silicon Labs CP2112 HID USB-to-SMBus Bridge support"
+	depends on USB_HID && I2C
+	---help---
+	Support for Silicon Labs CP2112 HID USB to SMBus Master Bridge.
+	This is a HID device driver which registers as an i2c adapter
+	and gpiochip to expose these functions of the CP2112. The
+	customizable USB descriptor fields are exposed as sysfs attributes.
+
 config HID_CYPRESS
 	tristate "Cypress mouse and barcode readers" if EXPERT
 	depends on HID
diff --git a/drivers/hid/Makefile b/drivers/hid/Makefile
index 30e4431..fc712dd 100644
--- a/drivers/hid/Makefile
+++ b/drivers/hid/Makefile
@@ -41,6 +41,7 @@
 obj-$(CONFIG_HID_BELKIN)	+= hid-belkin.o
 obj-$(CONFIG_HID_CHERRY)	+= hid-cherry.o
 obj-$(CONFIG_HID_CHICONY)	+= hid-chicony.o
+obj-$(CONFIG_HID_CP2112)	+= hid-cp2112.o
 obj-$(CONFIG_HID_CYPRESS)	+= hid-cypress.o
 obj-$(CONFIG_HID_DRAGONRISE)	+= hid-dr.o
 obj-$(CONFIG_HID_EMS_FF)	+= hid-emsff.o
diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 026ab0f..5ca6fe7 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -1692,6 +1692,7 @@
 	{ HID_USB_DEVICE(USB_VENDOR_ID_CHICONY, USB_DEVICE_ID_CHICONY_WIRELESS2) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_CHICONY, USB_DEVICE_ID_CHICONY_AK1D) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_CREATIVELABS, USB_DEVICE_ID_PRODIKEYS_PCMIDI) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_CYGNAL, USB_DEVICE_ID_CYGNAL_CP2112) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_CYPRESS, USB_DEVICE_ID_CYPRESS_BARCODE_1) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_CYPRESS, USB_DEVICE_ID_CYPRESS_BARCODE_2) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_CYPRESS, USB_DEVICE_ID_CYPRESS_BARCODE_3) },
diff --git a/drivers/hid/hid-cp2112.c b/drivers/hid/hid-cp2112.c
new file mode 100644
index 0000000..ca0f356
--- /dev/null
+++ b/drivers/hid/hid-cp2112.c
@@ -0,0 +1,1066 @@
+/*
+ * hid-cp2112.c - Silicon Labs HID USB to SMBus master bridge
+ * Copyright (c) 2013,2014 Uplogix, Inc.
+ * David Barksdale <dbarksdale@uplogix.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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.
+ */
+
+/*
+ * The Silicon Labs CP2112 chip is a USB HID device which provides an
+ * SMBus controller for talking to slave devices and 8 GPIO pins. The
+ * host communicates with the CP2112 via raw HID reports.
+ *
+ * Data Sheet:
+ *   http://www.silabs.com/Support%20Documents/TechnicalDocs/CP2112.pdf
+ * Programming Interface Specification:
+ *   http://www.silabs.com/Support%20Documents/TechnicalDocs/AN495.pdf
+ */
+
+#include <linux/gpio.h>
+#include <linux/hid.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/nls.h>
+#include <linux/usb/ch9.h>
+#include "hid-ids.h"
+
+enum {
+	CP2112_GPIO_CONFIG		= 0x02,
+	CP2112_GPIO_GET			= 0x03,
+	CP2112_GPIO_SET			= 0x04,
+	CP2112_GET_VERSION_INFO		= 0x05,
+	CP2112_SMBUS_CONFIG		= 0x06,
+	CP2112_DATA_READ_REQUEST	= 0x10,
+	CP2112_DATA_WRITE_READ_REQUEST	= 0x11,
+	CP2112_DATA_READ_FORCE_SEND	= 0x12,
+	CP2112_DATA_READ_RESPONSE	= 0x13,
+	CP2112_DATA_WRITE_REQUEST	= 0x14,
+	CP2112_TRANSFER_STATUS_REQUEST	= 0x15,
+	CP2112_TRANSFER_STATUS_RESPONSE	= 0x16,
+	CP2112_CANCEL_TRANSFER		= 0x17,
+	CP2112_LOCK_BYTE		= 0x20,
+	CP2112_USB_CONFIG		= 0x21,
+	CP2112_MANUFACTURER_STRING	= 0x22,
+	CP2112_PRODUCT_STRING		= 0x23,
+	CP2112_SERIAL_STRING		= 0x24,
+};
+
+enum {
+	STATUS0_IDLE		= 0x00,
+	STATUS0_BUSY		= 0x01,
+	STATUS0_COMPLETE	= 0x02,
+	STATUS0_ERROR		= 0x03,
+};
+
+enum {
+	STATUS1_TIMEOUT_NACK		= 0x00,
+	STATUS1_TIMEOUT_BUS		= 0x01,
+	STATUS1_ARBITRATION_LOST	= 0x02,
+	STATUS1_READ_INCOMPLETE		= 0x03,
+	STATUS1_WRITE_INCOMPLETE	= 0x04,
+	STATUS1_SUCCESS			= 0x05,
+};
+
+struct cp2112_smbus_config_report {
+	u8 report;		/* CP2112_SMBUS_CONFIG */
+	__be32 clock_speed;	/* Hz */
+	u8 device_address;	/* Stored in the upper 7 bits */
+	u8 auto_send_read;	/* 1 = enabled, 0 = disabled */
+	__be16 write_timeout;	/* ms, 0 = no timeout */
+	__be16 read_timeout;	/* ms, 0 = no timeout */
+	u8 scl_low_timeout;	/* 1 = enabled, 0 = disabled */
+	__be16 retry_time;	/* # of retries, 0 = no limit */
+} __packed;
+
+struct cp2112_usb_config_report {
+	u8 report;	/* CP2112_USB_CONFIG */
+	__le16 vid;	/* Vendor ID */
+	__le16 pid;	/* Product ID */
+	u8 max_power;	/* Power requested in 2mA units */
+	u8 power_mode;	/* 0x00 = bus powered
+			   0x01 = self powered & regulator off
+			   0x02 = self powered & regulator on */
+	u8 release_major;
+	u8 release_minor;
+	u8 mask;	/* What fields to program */
+} __packed;
+
+struct cp2112_read_req_report {
+	u8 report;	/* CP2112_DATA_READ_REQUEST */
+	u8 slave_address;
+	__be16 length;
+} __packed;
+
+struct cp2112_write_read_req_report {
+	u8 report;	/* CP2112_DATA_WRITE_READ_REQUEST */
+	u8 slave_address;
+	__be16 length;
+	u8 target_address_length;
+	u8 target_address[16];
+} __packed;
+
+struct cp2112_write_req_report {
+	u8 report;	/* CP2112_DATA_WRITE_REQUEST */
+	u8 slave_address;
+	u8 length;
+	u8 data[61];
+} __packed;
+
+struct cp2112_force_read_report {
+	u8 report;	/* CP2112_DATA_READ_FORCE_SEND */
+	__be16 length;
+} __packed;
+
+struct cp2112_xfer_status_report {
+	u8 report;	/* CP2112_TRANSFER_STATUS_RESPONSE */
+	u8 status0;	/* STATUS0_* */
+	u8 status1;	/* STATUS1_* */
+	__be16 retries;
+	__be16 length;
+} __packed;
+
+struct cp2112_string_report {
+	u8 dummy;		/* force .string to be aligned */
+	u8 report;		/* CP2112_*_STRING */
+	u8 length;		/* length in bytes of everyting after .report */
+	u8 type;		/* USB_DT_STRING */
+	wchar_t string[30];	/* UTF16_LITTLE_ENDIAN string */
+} __packed;
+
+/* Number of times to request transfer status before giving up waiting for a
+   transfer to complete. This may need to be changed if SMBUS clock, retries,
+   or read/write/scl_low timeout settings are changed. */
+static const int XFER_STATUS_RETRIES = 10;
+
+/* Time in ms to wait for a CP2112_DATA_READ_RESPONSE or
+   CP2112_TRANSFER_STATUS_RESPONSE. */
+static const int RESPONSE_TIMEOUT = 50;
+
+static const struct hid_device_id cp2112_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_CYGNAL, USB_DEVICE_ID_CYGNAL_CP2112) },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, cp2112_devices);
+
+struct cp2112_device {
+	struct i2c_adapter adap;
+	struct hid_device *hdev;
+	wait_queue_head_t wait;
+	u8 read_data[61];
+	u8 read_length;
+	int xfer_status;
+	atomic_t read_avail;
+	atomic_t xfer_avail;
+	struct gpio_chip gc;
+};
+
+static int gpio_push_pull = 0xFF;
+module_param(gpio_push_pull, int, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(gpio_push_pull, "GPIO push-pull configuration bitmask");
+
+static int cp2112_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
+{
+	struct cp2112_device *dev = container_of(chip, struct cp2112_device,
+						 gc);
+	struct hid_device *hdev = dev->hdev;
+	u8 buf[5];
+	int ret;
+
+	ret = hdev->hid_get_raw_report(hdev, CP2112_GPIO_CONFIG, buf,
+				       sizeof(buf), HID_FEATURE_REPORT);
+	if (ret != sizeof(buf)) {
+		hid_err(hdev, "error requesting GPIO config: %d\n", ret);
+		return ret;
+	}
+
+	buf[1] &= ~(1 << offset);
+	buf[2] = gpio_push_pull;
+
+	ret = hdev->hid_output_raw_report(hdev, buf, sizeof(buf),
+					  HID_FEATURE_REPORT);
+	if (ret < 0) {
+		hid_err(hdev, "error setting GPIO config: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void cp2112_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
+{
+	struct cp2112_device *dev = container_of(chip, struct cp2112_device,
+						 gc);
+	struct hid_device *hdev = dev->hdev;
+	u8 buf[3];
+	int ret;
+
+	buf[0] = CP2112_GPIO_SET;
+	buf[1] = value ? 0xff : 0;
+	buf[2] = 1 << offset;
+
+	ret = hdev->hid_output_raw_report(hdev, buf, sizeof(buf),
+					  HID_FEATURE_REPORT);
+	if (ret < 0)
+		hid_err(hdev, "error setting GPIO values: %d\n", ret);
+}
+
+static int cp2112_gpio_get(struct gpio_chip *chip, unsigned offset)
+{
+	struct cp2112_device *dev = container_of(chip, struct cp2112_device,
+						 gc);
+	struct hid_device *hdev = dev->hdev;
+	u8 buf[2];
+	int ret;
+
+	ret = hdev->hid_get_raw_report(hdev, CP2112_GPIO_GET, buf, sizeof(buf),
+				       HID_FEATURE_REPORT);
+	if (ret != sizeof(buf)) {
+		hid_err(hdev, "error requesting GPIO values: %d\n", ret);
+		return ret;
+	}
+
+	return (buf[1] >> offset) & 1;
+}
+
+static int cp2112_gpio_direction_output(struct gpio_chip *chip,
+					unsigned offset, int value)
+{
+	struct cp2112_device *dev = container_of(chip, struct cp2112_device,
+						 gc);
+	struct hid_device *hdev = dev->hdev;
+	u8 buf[5];
+	int ret;
+
+	cp2112_gpio_set(chip, offset, value);
+
+	ret = hdev->hid_get_raw_report(hdev, CP2112_GPIO_CONFIG, buf,
+				       sizeof(buf), HID_FEATURE_REPORT);
+	if (ret != sizeof(buf)) {
+		hid_err(hdev, "error requesting GPIO config: %d\n", ret);
+		return ret;
+	}
+
+	buf[1] |= 1 << offset;
+	buf[2] = gpio_push_pull;
+
+	ret = hdev->hid_output_raw_report(hdev, buf, sizeof(buf),
+					  HID_FEATURE_REPORT);
+	if (ret < 0) {
+		hid_err(hdev, "error setting GPIO config: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int cp2112_hid_get(struct hid_device *hdev, unsigned char report_number,
+			  u8 *data, size_t count, unsigned char report_type)
+{
+	u8 *buf;
+	int ret;
+
+	buf = kmalloc(count, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	ret = hdev->hid_get_raw_report(hdev, report_number, buf, count,
+				       report_type);
+	memcpy(data, buf, count);
+	kfree(buf);
+	return ret;
+}
+
+static int cp2112_hid_output(struct hid_device *hdev, u8 *data, size_t count,
+			     unsigned char report_type)
+{
+	u8 *buf;
+	int ret;
+
+	buf = kmemdup(data, count, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	ret = hdev->hid_output_raw_report(hdev, buf, count, report_type);
+	kfree(buf);
+	return ret;
+}
+
+static int cp2112_wait(struct cp2112_device *dev, atomic_t *avail)
+{
+	int ret = 0;
+
+	/* We have sent either a CP2112_TRANSFER_STATUS_REQUEST or a
+	 * CP2112_DATA_READ_FORCE_SEND and we are waiting for the response to
+	 * come in cp2112_raw_event or timeout. There will only be one of these
+	 * in flight at any one time. The timeout is extremely large and is a
+	 * last resort if the CP2112 has died. If we do timeout we don't expect
+	 * to receive the response which would cause data races, it's not like
+	 * we can do anything about it anyway.
+	 */
+	ret = wait_event_interruptible_timeout(dev->wait,
+		atomic_read(avail), msecs_to_jiffies(RESPONSE_TIMEOUT));
+	if (-ERESTARTSYS == ret)
+		return ret;
+	if (!ret)
+		return -ETIMEDOUT;
+
+	atomic_set(avail, 0);
+	return 0;
+}
+
+static int cp2112_xfer_status(struct cp2112_device *dev)
+{
+	struct hid_device *hdev = dev->hdev;
+	u8 buf[2];
+	int ret;
+
+	buf[0] = CP2112_TRANSFER_STATUS_REQUEST;
+	buf[1] = 0x01;
+	atomic_set(&dev->xfer_avail, 0);
+
+	ret = cp2112_hid_output(hdev, buf, 2, HID_OUTPUT_REPORT);
+	if (ret < 0) {
+		hid_warn(hdev, "Error requesting status: %d\n", ret);
+		return ret;
+	}
+
+	ret = cp2112_wait(dev, &dev->xfer_avail);
+	if (ret)
+		return ret;
+
+	return dev->xfer_status;
+}
+
+static int cp2112_read(struct cp2112_device *dev, u8 *data, size_t size)
+{
+	struct hid_device *hdev = dev->hdev;
+	struct cp2112_force_read_report report;
+	int ret;
+
+	report.report = CP2112_DATA_READ_FORCE_SEND;
+	report.length = cpu_to_be16(size);
+
+	atomic_set(&dev->read_avail, 0);
+
+	ret = cp2112_hid_output(hdev, &report.report, sizeof(report),
+				HID_OUTPUT_REPORT);
+	if (ret < 0) {
+		hid_warn(hdev, "Error requesting data: %d\n", ret);
+		return ret;
+	}
+
+	ret = cp2112_wait(dev, &dev->read_avail);
+	if (ret)
+		return ret;
+
+	hid_dbg(hdev, "read %d of %d bytes requested\n",
+		dev->read_length, size);
+
+	if (size > dev->read_length)
+		size = dev->read_length;
+
+	memcpy(data, dev->read_data, size);
+	return dev->read_length;
+}
+
+static int cp2112_read_req(void *buf, u8 slave_address, u16 length)
+{
+	struct cp2112_read_req_report *report = buf;
+
+	if (length < 1 || length > 512)
+		return -EINVAL;
+
+	report->report = CP2112_DATA_READ_REQUEST;
+	report->slave_address = slave_address << 1;
+	report->length = cpu_to_be16(length);
+	return sizeof(*report);
+}
+
+static int cp2112_write_read_req(void *buf, u8 slave_address, u16 length,
+				 u8 command, u8 *data, u8 data_length)
+{
+	struct cp2112_write_read_req_report *report = buf;
+
+	if (length < 1 || length > 512
+	    || data_length > sizeof(report->target_address) - 1)
+		return -EINVAL;
+
+	report->report = CP2112_DATA_WRITE_READ_REQUEST;
+	report->slave_address = slave_address << 1;
+	report->length = cpu_to_be16(length);
+	report->target_address_length = data_length + 1;
+	report->target_address[0] = command;
+	memcpy(&report->target_address[1], data, data_length);
+	return data_length + 6;
+}
+
+static int cp2112_write_req(void *buf, u8 slave_address, u8 command, u8 *data,
+			    u8 data_length)
+{
+	struct cp2112_write_req_report *report = buf;
+
+	if (data_length > sizeof(report->data) - 1)
+		return -EINVAL;
+
+	report->report = CP2112_DATA_WRITE_REQUEST;
+	report->slave_address = slave_address << 1;
+	report->length = data_length + 1;
+	report->data[0] = command;
+	memcpy(&report->data[1], data, data_length);
+	return data_length + 4;
+}
+
+static int cp2112_xfer(struct i2c_adapter *adap, u16 addr,
+		       unsigned short flags, char read_write, u8 command,
+		       int size, union i2c_smbus_data *data)
+{
+	struct cp2112_device *dev = (struct cp2112_device *)adap->algo_data;
+	struct hid_device *hdev = dev->hdev;
+	u8 buf[64];
+	__be16 word;
+	size_t count;
+	size_t read_length = 0;
+	unsigned int retries;
+	int ret;
+
+	hid_dbg(hdev, "%s addr 0x%x flags 0x%x cmd 0x%x size %d\n",
+		read_write == I2C_SMBUS_WRITE ? "write" : "read",
+		addr, flags, command, size);
+
+	switch (size) {
+	case I2C_SMBUS_BYTE:
+		read_length = 1;
+
+		if (I2C_SMBUS_READ == read_write)
+			count = cp2112_read_req(buf, addr, read_length);
+		else
+			count = cp2112_write_req(buf, addr, data->byte, NULL,
+						 0);
+		break;
+	case I2C_SMBUS_BYTE_DATA:
+		read_length = 1;
+
+		if (I2C_SMBUS_READ == read_write)
+			count = cp2112_write_read_req(buf, addr, read_length,
+						      command, NULL, 0);
+		else
+			count = cp2112_write_req(buf, addr, command,
+						 &data->byte, 1);
+		break;
+	case I2C_SMBUS_WORD_DATA:
+		read_length = 2;
+		word = cpu_to_be16(data->word);
+
+		if (I2C_SMBUS_READ == read_write)
+			count = cp2112_write_read_req(buf, addr, read_length,
+						      command, NULL, 0);
+		else
+			count = cp2112_write_req(buf, addr, command,
+						 (u8 *)&word, 2);
+		break;
+	case I2C_SMBUS_PROC_CALL:
+		size = I2C_SMBUS_WORD_DATA;
+		read_write = I2C_SMBUS_READ;
+		read_length = 2;
+		word = cpu_to_be16(data->word);
+
+		count = cp2112_write_read_req(buf, addr, read_length, command,
+					      (u8 *)&word, 2);
+		break;
+	case I2C_SMBUS_I2C_BLOCK_DATA:
+		size = I2C_SMBUS_BLOCK_DATA;
+		/* fallthrough */
+	case I2C_SMBUS_BLOCK_DATA:
+		if (I2C_SMBUS_READ == read_write) {
+			count = cp2112_write_read_req(buf, addr,
+						      I2C_SMBUS_BLOCK_MAX,
+						      command, NULL, 0);
+		} else {
+			count = cp2112_write_req(buf, addr, command,
+						 data->block,
+						 data->block[0] + 1);
+		}
+		break;
+	case I2C_SMBUS_BLOCK_PROC_CALL:
+		size = I2C_SMBUS_BLOCK_DATA;
+		read_write = I2C_SMBUS_READ;
+
+		count = cp2112_write_read_req(buf, addr, I2C_SMBUS_BLOCK_MAX,
+					      command, data->block,
+					      data->block[0] + 1);
+		break;
+	default:
+		hid_warn(hdev, "Unsupported transaction %d\n", size);
+		return -EOPNOTSUPP;
+	}
+
+	if (count < 0)
+		return count;
+
+	ret = hid_hw_power(hdev, PM_HINT_FULLON);
+	if (ret < 0) {
+		hid_err(hdev, "power management error: %d\n", ret);
+		return ret;
+	}
+
+	ret = cp2112_hid_output(hdev, buf, count, HID_OUTPUT_REPORT);
+	if (ret < 0) {
+		hid_warn(hdev, "Error starting transaction: %d\n", ret);
+		goto power_normal;
+	}
+
+	for (retries = 0; retries < XFER_STATUS_RETRIES; ++retries) {
+		ret = cp2112_xfer_status(dev);
+		if (-EBUSY == ret)
+			continue;
+		if (ret < 0)
+			goto power_normal;
+		break;
+	}
+
+	if (XFER_STATUS_RETRIES <= retries) {
+		hid_warn(hdev, "Transfer timed out, cancelling.\n");
+		buf[0] = CP2112_CANCEL_TRANSFER;
+		buf[1] = 0x01;
+
+		ret = cp2112_hid_output(hdev, buf, 2, HID_OUTPUT_REPORT);
+		if (ret < 0)
+			hid_warn(hdev, "Error cancelling transaction: %d\n",
+				 ret);
+
+		ret = -ETIMEDOUT;
+		goto power_normal;
+	}
+
+	if (I2C_SMBUS_WRITE == read_write) {
+		ret = 0;
+		goto power_normal;
+	}
+
+	if (I2C_SMBUS_BLOCK_DATA == size)
+		read_length = ret;
+
+	ret = cp2112_read(dev, buf, read_length);
+	if (ret < 0)
+		goto power_normal;
+	if (ret != read_length) {
+		hid_warn(hdev, "short read: %d < %d\n", ret, read_length);
+		ret = -EIO;
+		goto power_normal;
+	}
+
+	switch (size) {
+	case I2C_SMBUS_BYTE:
+	case I2C_SMBUS_BYTE_DATA:
+		data->byte = buf[0];
+		break;
+	case I2C_SMBUS_WORD_DATA:
+		data->word = be16_to_cpup((__be16 *)buf);
+		break;
+	case I2C_SMBUS_BLOCK_DATA:
+		if (read_length > I2C_SMBUS_BLOCK_MAX) {
+			ret = -EPROTO;
+			goto power_normal;
+		}
+
+		memcpy(data->block, buf, read_length);
+		break;
+	}
+
+	ret = 0;
+power_normal:
+	hid_hw_power(hdev, PM_HINT_NORMAL);
+	hid_dbg(hdev, "transfer finished: %d\n", ret);
+	return ret;
+}
+
+static u32 cp2112_functionality(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_SMBUS_BYTE |
+		I2C_FUNC_SMBUS_BYTE_DATA |
+		I2C_FUNC_SMBUS_WORD_DATA |
+		I2C_FUNC_SMBUS_BLOCK_DATA |
+		I2C_FUNC_SMBUS_I2C_BLOCK |
+		I2C_FUNC_SMBUS_PROC_CALL |
+		I2C_FUNC_SMBUS_BLOCK_PROC_CALL;
+}
+
+static const struct i2c_algorithm smbus_algorithm = {
+	.smbus_xfer	= cp2112_xfer,
+	.functionality	= cp2112_functionality,
+};
+
+static int cp2112_get_usb_config(struct hid_device *hdev,
+				 struct cp2112_usb_config_report *cfg)
+{
+	int ret;
+
+	ret = cp2112_hid_get(hdev, CP2112_USB_CONFIG, (u8 *)cfg, sizeof(*cfg),
+			     HID_FEATURE_REPORT);
+	if (ret != sizeof(*cfg)) {
+		hid_err(hdev, "error reading usb config: %d\n", ret);
+		if (ret < 0)
+			return ret;
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static int cp2112_set_usb_config(struct hid_device *hdev,
+				 struct cp2112_usb_config_report *cfg)
+{
+	int ret;
+
+	BUG_ON(cfg->report != CP2112_USB_CONFIG);
+
+	ret = cp2112_hid_output(hdev, (u8 *)cfg, sizeof(*cfg),
+				HID_FEATURE_REPORT);
+	if (ret != sizeof(*cfg)) {
+		hid_err(hdev, "error writing usb config: %d\n", ret);
+		if (ret < 0)
+			return ret;
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static void chmod_sysfs_attrs(struct hid_device *hdev);
+
+#define CP2112_CONFIG_ATTR(name, store, format, ...) \
+static ssize_t name##_store(struct device *kdev, \
+			    struct device_attribute *attr, const char *buf, \
+			    size_t count) \
+{ \
+	struct hid_device *hdev = container_of(kdev, struct hid_device, dev); \
+	struct cp2112_usb_config_report cfg; \
+	int ret = cp2112_get_usb_config(hdev, &cfg); \
+	if (ret) \
+		return ret; \
+	store; \
+	ret = cp2112_set_usb_config(hdev, &cfg); \
+	if (ret) \
+		return ret; \
+	chmod_sysfs_attrs(hdev); \
+	return count; \
+} \
+static ssize_t name##_show(struct device *kdev, \
+			   struct device_attribute *attr, char *buf) \
+{ \
+	struct hid_device *hdev = container_of(kdev, struct hid_device, dev); \
+	struct cp2112_usb_config_report cfg; \
+	int ret = cp2112_get_usb_config(hdev, &cfg); \
+	if (ret) \
+		return ret; \
+	return scnprintf(buf, PAGE_SIZE, format, ##__VA_ARGS__); \
+} \
+DEVICE_ATTR_RW(name);
+
+CP2112_CONFIG_ATTR(vendor_id, ({
+	u16 vid;
+
+	if (sscanf(buf, "%hi", &vid) != 1)
+		return -EINVAL;
+
+	cfg.vid = cpu_to_le16(vid);
+	cfg.mask = 0x01;
+}), "0x%04x\n", le16_to_cpu(cfg.vid));
+
+CP2112_CONFIG_ATTR(product_id, ({
+	u16 pid;
+
+	if (sscanf(buf, "%hi", &pid) != 1)
+		return -EINVAL;
+
+	cfg.pid = cpu_to_le16(pid);
+	cfg.mask = 0x02;
+}), "0x%04x\n", le16_to_cpu(cfg.pid));
+
+CP2112_CONFIG_ATTR(max_power, ({
+	int mA;
+
+	if (sscanf(buf, "%i", &mA) != 1)
+		return -EINVAL;
+
+	cfg.max_power = (mA + 1) / 2;
+	cfg.mask = 0x04;
+}), "%u mA\n", cfg.max_power * 2);
+
+CP2112_CONFIG_ATTR(power_mode, ({
+	if (sscanf(buf, "%hhi", &cfg.power_mode) != 1)
+		return -EINVAL;
+
+	cfg.mask = 0x08;
+}), "%u\n", cfg.power_mode);
+
+CP2112_CONFIG_ATTR(release_version, ({
+	if (sscanf(buf, "%hhi.%hhi", &cfg.release_major, &cfg.release_minor)
+	    != 2)
+		return -EINVAL;
+
+	cfg.mask = 0x10;
+}), "%u.%u\n", cfg.release_major, cfg.release_minor);
+
+#undef CP2112_CONFIG_ATTR
+
+struct cp2112_pstring_attribute {
+	struct device_attribute attr;
+	unsigned char report;
+};
+
+static ssize_t pstr_store(struct device *kdev,
+			  struct device_attribute *kattr, const char *buf,
+			  size_t count)
+{
+	struct hid_device *hdev = container_of(kdev, struct hid_device, dev);
+	struct cp2112_pstring_attribute *attr =
+		container_of(kattr, struct cp2112_pstring_attribute, attr);
+	struct cp2112_string_report report;
+	int ret;
+
+	memset(&report, 0, sizeof(report));
+
+	ret = utf8s_to_utf16s(buf, count, UTF16_LITTLE_ENDIAN,
+			      report.string, ARRAY_SIZE(report.string));
+	report.report = attr->report;
+	report.length = ret * sizeof(report.string[0]) + 2;
+	report.type = USB_DT_STRING;
+
+	ret = cp2112_hid_output(hdev, &report.report, report.length + 1,
+				HID_FEATURE_REPORT);
+	if (ret != report.length + 1) {
+		hid_err(hdev, "error writing %s string: %d\n", kattr->attr.name,
+			ret);
+		if (ret < 0)
+			return ret;
+		return -EIO;
+	}
+
+	chmod_sysfs_attrs(hdev);
+	return count;
+}
+
+static ssize_t pstr_show(struct device *kdev,
+			 struct device_attribute *kattr, char *buf)
+{
+	struct hid_device *hdev = container_of(kdev, struct hid_device, dev);
+	struct cp2112_pstring_attribute *attr =
+		container_of(kattr, struct cp2112_pstring_attribute, attr);
+	struct cp2112_string_report report;
+	u8 length;
+	int ret;
+
+	ret = cp2112_hid_get(hdev, attr->report, &report.report,
+			     sizeof(report) - 1, HID_FEATURE_REPORT);
+	if (ret < 3) {
+		hid_err(hdev, "error reading %s string: %d\n", kattr->attr.name,
+			ret);
+		if (ret < 0)
+			return ret;
+		return -EIO;
+	}
+
+	if (report.length < 2) {
+		hid_err(hdev, "invalid %s string length: %d\n",
+			kattr->attr.name, report.length);
+		return -EIO;
+	}
+
+	length = report.length > ret - 1 ? ret - 1 : report.length;
+	length = (length - 2) / sizeof(report.string[0]);
+	ret = utf16s_to_utf8s(report.string, length, UTF16_LITTLE_ENDIAN, buf,
+			      PAGE_SIZE - 1);
+	buf[ret++] = '\n';
+	return ret;
+}
+
+#define CP2112_PSTR_ATTR(name, _report) \
+struct cp2112_pstring_attribute dev_attr_##name = { \
+	.attr = __ATTR(name, (S_IWUSR | S_IRUGO), pstr_show, pstr_store), \
+	.report = _report, \
+};
+
+CP2112_PSTR_ATTR(manufacturer,	CP2112_MANUFACTURER_STRING);
+CP2112_PSTR_ATTR(product,	CP2112_PRODUCT_STRING);
+CP2112_PSTR_ATTR(serial,	CP2112_SERIAL_STRING);
+
+#undef CP2112_PSTR_ATTR
+
+static const struct attribute_group cp2112_attr_group = {
+	.attrs = (struct attribute *[]){
+		&dev_attr_vendor_id.attr,
+		&dev_attr_product_id.attr,
+		&dev_attr_max_power.attr,
+		&dev_attr_power_mode.attr,
+		&dev_attr_release_version.attr,
+		&dev_attr_manufacturer.attr.attr,
+		&dev_attr_product.attr.attr,
+		&dev_attr_serial.attr.attr,
+		NULL
+	}
+};
+
+/* Chmoding our sysfs attributes is simply a way to expose which fields in the
+ * PROM have already been programmed. We do not depend on this preventing
+ * writing to these attributes since the CP2112 will simply ignore writes to
+ * already-programmed fields. This is why there is no sense in fixing this
+ * racy behaviour.
+ */
+static void chmod_sysfs_attrs(struct hid_device *hdev)
+{
+	struct attribute **attr;
+	u8 buf[2];
+	int ret;
+
+	ret = cp2112_hid_get(hdev, CP2112_LOCK_BYTE, buf, sizeof(buf),
+			     HID_FEATURE_REPORT);
+	if (ret != sizeof(buf)) {
+		hid_err(hdev, "error reading lock byte: %d\n", ret);
+		return;
+	}
+
+	for (attr = cp2112_attr_group.attrs; *attr; ++attr) {
+		umode_t mode = (buf[1] & 1) ? S_IWUSR | S_IRUGO : S_IRUGO;
+		ret = sysfs_chmod_file(&hdev->dev.kobj, *attr, mode);
+		if (ret < 0)
+			hid_err(hdev, "error chmoding sysfs file %s\n",
+				(*attr)->name);
+		buf[1] >>= 1;
+	}
+}
+
+static int cp2112_probe(struct hid_device *hdev, const struct hid_device_id *id)
+{
+	struct cp2112_device *dev;
+	u8 buf[3];
+	struct cp2112_smbus_config_report config;
+	int ret;
+
+	ret = hid_parse(hdev);
+	if (ret) {
+		hid_err(hdev, "parse failed\n");
+		return ret;
+	}
+
+	ret = hid_hw_start(hdev, HID_CONNECT_HIDRAW);
+	if (ret) {
+		hid_err(hdev, "hw start failed\n");
+		return ret;
+	}
+
+	ret = hid_hw_open(hdev);
+	if (ret) {
+		hid_err(hdev, "hw open failed\n");
+		goto err_hid_stop;
+	}
+
+	ret = hid_hw_power(hdev, PM_HINT_FULLON);
+	if (ret < 0) {
+		hid_err(hdev, "power management error: %d\n", ret);
+		goto err_hid_close;
+	}
+
+	ret = cp2112_hid_get(hdev, CP2112_GET_VERSION_INFO, buf, sizeof(buf),
+			     HID_FEATURE_REPORT);
+	if (ret != sizeof(buf)) {
+		hid_err(hdev, "error requesting version\n");
+		if (ret >= 0)
+			ret = -EIO;
+		goto err_power_normal;
+	}
+
+	hid_info(hdev, "Part Number: 0x%02X Device Version: 0x%02X\n",
+		 buf[1], buf[2]);
+
+	ret = cp2112_hid_get(hdev, CP2112_SMBUS_CONFIG, (u8 *)&config,
+			     sizeof(config), HID_FEATURE_REPORT);
+	if (ret != sizeof(config)) {
+		hid_err(hdev, "error requesting SMBus config\n");
+		if (ret >= 0)
+			ret = -EIO;
+		goto err_power_normal;
+	}
+
+	config.retry_time = cpu_to_be16(1);
+
+	ret = cp2112_hid_output(hdev, (u8 *)&config, sizeof(config),
+				HID_FEATURE_REPORT);
+	if (ret != sizeof(config)) {
+		hid_err(hdev, "error setting SMBus config\n");
+		if (ret >= 0)
+			ret = -EIO;
+		goto err_power_normal;
+	}
+
+	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+	if (!dev) {
+		ret = -ENOMEM;
+		goto err_power_normal;
+	}
+
+	hid_set_drvdata(hdev, (void *)dev);
+	dev->hdev		= hdev;
+	dev->adap.owner		= THIS_MODULE;
+	dev->adap.class		= I2C_CLASS_HWMON;
+	dev->adap.algo		= &smbus_algorithm;
+	dev->adap.algo_data	= dev;
+	dev->adap.dev.parent	= &hdev->dev;
+	snprintf(dev->adap.name, sizeof(dev->adap.name),
+		 "CP2112 SMBus Bridge on hiddev%d", hdev->minor);
+	init_waitqueue_head(&dev->wait);
+
+	hid_device_io_start(hdev);
+	ret = i2c_add_adapter(&dev->adap);
+	hid_device_io_stop(hdev);
+
+	if (ret) {
+		hid_err(hdev, "error registering i2c adapter\n");
+		goto err_free_dev;
+	}
+
+	hid_dbg(hdev, "adapter registered\n");
+
+	dev->gc.label			= "cp2112_gpio";
+	dev->gc.direction_input		= cp2112_gpio_direction_input;
+	dev->gc.direction_output	= cp2112_gpio_direction_output;
+	dev->gc.set			= cp2112_gpio_set;
+	dev->gc.get			= cp2112_gpio_get;
+	dev->gc.base			= -1;
+	dev->gc.ngpio			= 8;
+	dev->gc.can_sleep		= 1;
+	dev->gc.dev			= &hdev->dev;
+
+	ret = gpiochip_add(&dev->gc);
+	if (ret < 0) {
+		hid_err(hdev, "error registering gpio chip\n");
+		goto err_free_i2c;
+	}
+
+	ret = sysfs_create_group(&hdev->dev.kobj, &cp2112_attr_group);
+	if (ret < 0) {
+		hid_err(hdev, "error creating sysfs attrs\n");
+		goto err_gpiochip_remove;
+	}
+
+	chmod_sysfs_attrs(hdev);
+	hid_hw_power(hdev, PM_HINT_NORMAL);
+
+	return ret;
+
+err_gpiochip_remove:
+	if (gpiochip_remove(&dev->gc) < 0)
+		hid_err(hdev, "error removing gpio chip\n");
+err_free_i2c:
+	i2c_del_adapter(&dev->adap);
+err_free_dev:
+	kfree(dev);
+err_power_normal:
+	hid_hw_power(hdev, PM_HINT_NORMAL);
+err_hid_close:
+	hid_hw_close(hdev);
+err_hid_stop:
+	hid_hw_stop(hdev);
+	return ret;
+}
+
+static void cp2112_remove(struct hid_device *hdev)
+{
+	struct cp2112_device *dev = hid_get_drvdata(hdev);
+
+	sysfs_remove_group(&hdev->dev.kobj, &cp2112_attr_group);
+	if (gpiochip_remove(&dev->gc))
+		hid_err(hdev, "unable to remove gpio chip\n");
+	i2c_del_adapter(&dev->adap);
+	/* i2c_del_adapter has finished removing all i2c devices from our
+	 * adapter. Well behaved devices should no longer call our cp2112_xfer
+	 * and should have waited for any pending calls to finish. It has also
+	 * waited for device_unregister(&adap->dev) to complete. Therefore we
+	 * can safely free our struct cp2112_device.
+	 */
+	hid_hw_close(hdev);
+	hid_hw_stop(hdev);
+	kfree(dev);
+}
+
+static int cp2112_raw_event(struct hid_device *hdev, struct hid_report *report,
+			    u8 *data, int size)
+{
+	struct cp2112_device *dev = hid_get_drvdata(hdev);
+	struct cp2112_xfer_status_report *xfer = (void *)data;
+
+	switch (data[0]) {
+	case CP2112_TRANSFER_STATUS_RESPONSE:
+		hid_dbg(hdev, "xfer status: %02x %02x %04x %04x\n",
+			xfer->status0, xfer->status1,
+			be16_to_cpu(xfer->retries), be16_to_cpu(xfer->length));
+
+		switch (xfer->status0) {
+		case STATUS0_IDLE:
+			dev->xfer_status = -EAGAIN;
+			break;
+		case STATUS0_BUSY:
+			dev->xfer_status = -EBUSY;
+			break;
+		case STATUS0_COMPLETE:
+			dev->xfer_status = be16_to_cpu(xfer->length);
+			break;
+		case STATUS0_ERROR:
+			switch (xfer->status1) {
+			case STATUS1_TIMEOUT_NACK:
+			case STATUS1_TIMEOUT_BUS:
+				dev->xfer_status = -ETIMEDOUT;
+				break;
+			default:
+				dev->xfer_status = -EIO;
+				break;
+			}
+			break;
+		default:
+			dev->xfer_status = -EINVAL;
+			break;
+		}
+
+		atomic_set(&dev->xfer_avail, 1);
+		break;
+	case CP2112_DATA_READ_RESPONSE:
+		hid_dbg(hdev, "read response: %02x %02x\n", data[1], data[2]);
+
+		dev->read_length = data[2];
+		if (dev->read_length > sizeof(dev->read_data))
+			dev->read_length = sizeof(dev->read_data);
+
+		memcpy(dev->read_data, &data[3], dev->read_length);
+		atomic_set(&dev->read_avail, 1);
+		break;
+	default:
+		hid_err(hdev, "unknown report\n");
+
+		return 0;
+	}
+
+	wake_up_interruptible(&dev->wait);
+	return 1;
+}
+
+static struct hid_driver cp2112_driver = {
+	.name		= "cp2112",
+	.id_table	= cp2112_devices,
+	.probe		= cp2112_probe,
+	.remove		= cp2112_remove,
+	.raw_event	= cp2112_raw_event,
+};
+
+module_hid_driver(cp2112_driver);
+MODULE_DESCRIPTION("Silicon Labs HID USB to SMBus master bridge");
+MODULE_AUTHOR("David Barksdale <dbarksdale@uplogix.com>");
+MODULE_LICENSE("GPL");
+
diff --git a/drivers/hid/hid-ids.h b/drivers/hid/hid-ids.h
index 92b40c0..239f29c 100644
--- a/drivers/hid/hid-ids.h
+++ b/drivers/hid/hid-ids.h
@@ -240,6 +240,7 @@
 
 #define USB_VENDOR_ID_CYGNAL		0x10c4
 #define USB_DEVICE_ID_CYGNAL_RADIO_SI470X	0x818a
+#define USB_DEVICE_ID_CYGNAL_CP2112	0xea90
 
 #define USB_VENDOR_ID_CYPRESS		0x04b4
 #define USB_DEVICE_ID_CYPRESS_MOUSE	0x0001