This patch adds support for the Silicon Labs CP2112
"Single-Chip HID USB to SMBus Master Bridge."

I wrote this to support a USB temperature and humidity
sensor I've been working on. It's been tested by using
SMBus byte-read, byte-data-read/write, and word-data-read
transfer modes to talk to an I2C sensor. The other
transfer modes have not been tested.

Signed-off-by: David Barksdale <dbarksd...@uplogix.com>

--
Changes since v1:
* Prefix symbols to avoid name collision.
* Define CP2112 device ID.
* Missing break.
* Use module_hid_driver().
* Fix cp2122 typo.
* Fix probe and remove functions.
* Remove #if in hid_have_special_driver[].
* Improve symbolic constants for timeouts.
* Wrap DMA functions to kmalloc buffers.
* Added a short description of the device.
* Add request formatting functions for readability.
* Whitespace changes.
* Fix endianess of word transfers.

However this version doesn't work. Adding the hid_hw_open/hid_hw_close
calls to cp2112_probe() as suggested by David Herrmann seems to have
stopped events being delivered to cp2112_raw_event(). Why is that?

---
 drivers/hid/Kconfig      |   6 +
 drivers/hid/Makefile     |   1 +
 drivers/hid/hid-core.c   |   1 +
 drivers/hid/hid-cp2112.c | 559 +++++++++++++++++++++++++++++++++++++++++++++++
 drivers/hid/hid-ids.h    |   1 +
 5 files changed, 568 insertions(+)

diff --git a/drivers/hid/Kconfig b/drivers/hid/Kconfig
index 14ef6ab..1833948 100644
--- a/drivers/hid/Kconfig
+++ b/drivers/hid/Kconfig
@@ -175,6 +175,12 @@ config HID_PRODIKEYS
          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
+       ---help---
+       Support for Silicon Labs CP2112 HID USB to SMBus Master Bridge.
+
 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 6f68728..a88a5c4 100644
--- a/drivers/hid/Makefile
+++ b/drivers/hid/Makefile
@@ -41,6 +41,7 @@ obj-$(CONFIG_HID_AUREAL)        += hid-aureal.o
 obj-$(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 36668d1..69e5f39 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -1568,6 +1568,7 @@ static const struct hid_device_id 
hid_have_special_driver[] = {
        { 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..5c6d294
--- /dev/null
+++ b/drivers/hid/hid-cp2112.c
@@ -0,0 +1,559 @@
+/*
+  hid-cp2112.c - Silicon Labs HID USB to SMBus master bridge
+  Copyright (c) 2013 Uplogix, Inc.
+  David Barksdale <dbarksd...@uplogix.com>
+
+  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., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+/*
+  The Silicon Labs CP2112 chip is a USB HID device which provides an
+  SMBus controller for talking to slave devices. The host communicates
+  with the CP2112 via raw HID reports.
+ */
+
+#include <linux/hid.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include "hid-ids.h"
+
+enum {
+       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,
+};
+
+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,
+};
+
+/* All values are in big-endian */
+struct __attribute__ ((__packed__)) cp2112_smbus_config {
+       uint32_t clock_speed; /* Hz */
+       uint8_t device_address; /* Stored in the upper 7 bits */
+       uint8_t auto_send_read; /* 1 = enabled, 0 = disabled */
+       uint16_t write_timeout; /* ms, 0 = no timeout */
+       uint16_t read_timeout; /* ms, 0 = no timeout */
+       uint8_t scl_low_timeout; /* 1 = enabled, 0 = disabled */
+       uint16_t retry_time; /* # of retries, 0 = no limit */
+};
+
+/* Number of times to request transfer status before giving up waiting for a
+   transfer to complete. */
+static const int XFER_TIMEOUT = 100;
+
+/* 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;
+       uint8_t read_data[61];
+       uint8_t read_length;
+       int xfer_status;
+       atomic_t read_avail;
+       atomic_t xfer_avail;
+};
+
+static int cp2112_wait(struct cp2112_device *dev, atomic_t *avail)
+{
+       int ret = 0;
+
+       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_hid_get(struct hid_device *hdev, unsigned char report_number,
+                         uint8_t *data, size_t count,
+                         unsigned char report_type)
+{
+       uint8_t *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, uint8_t *data,
+                            size_t count, unsigned char report_type)
+{
+       uint8_t *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_xfer_status(struct cp2112_device *dev)
+{
+       struct hid_device *hdev = dev->hdev;
+       uint8_t 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, uint8_t *data, size_t size)
+{
+       struct hid_device *hdev = dev->hdev;
+       uint8_t buf[3];
+       int ret;
+
+       buf[0] = CP2112_DATA_READ_FORCE_SEND;
+       *(uint16_t *)&buf[1] = htons(size);
+       atomic_set(&dev->read_avail, 0);
+       ret = cp2112_hid_output(hdev, buf, 3, 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(uint8_t *buf, uint8_t slave_address, uint16_t 
length)
+{
+       if (length < 1 || length > 512)
+               return -EINVAL;
+       buf[0] = CP2112_DATA_READ_REQUEST;
+       buf[1] = slave_address << 1;
+       *(uint16_t *)&buf[2] = htons(length);
+       return 4;
+}
+
+static int cp2112_write_read_req(uint8_t *buf, uint8_t slave_address,
+                                uint16_t length, uint8_t command,
+                                uint8_t *data, uint8_t data_length)
+{
+       if (length < 1 || length > 512 || data_length > 15)
+               return -EINVAL;
+       buf[0] = CP2112_DATA_WRITE_READ_REQUEST;
+       buf[1] = slave_address << 1;
+       *(uint16_t *)&buf[2] = htons(length);
+       buf[4] = data_length + 1;
+       buf[5] = command;
+       memcpy(&buf[6], data, data_length);
+       return data_length + 6;
+}
+
+static int cp2112_write_req(uint8_t *buf, uint8_t slave_address,
+                           uint8_t command, uint8_t *data, uint8_t data_length)
+{
+       if (data_length > 60)
+               return -EINVAL;
+       buf[0] = CP2112_DATA_WRITE_REQUEST;
+       buf[1] = slave_address << 1;
+       buf[2] = data_length + 1;
+       buf[3] = command;
+       memcpy(&buf[4], data, data_length);
+       return data_length + 4;
+}
+
+static int cp2112_xfer(struct i2c_adapter *adap, uint16_t addr,
+                      unsigned short flags, char read_write, uint8_t command,
+                      int size, union i2c_smbus_data *data)
+{
+       struct cp2112_device *dev = (struct cp2112_device *)adap->algo_data;
+       struct hid_device *hdev = dev->hdev;
+       uint8_t buf[64];
+       uint16_t word;
+       size_t count;
+       size_t read_length = 0;
+       size_t timeout;
+       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 = htons(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,
+                                                (uint8_t *)&word, 2);
+               break;
+       case I2C_SMBUS_PROC_CALL:
+               size = I2C_SMBUS_WORD_DATA;
+               read_write = I2C_SMBUS_READ;
+               read_length = 2;
+               word = htons(data->word);
+               count = cp2112_write_read_req(buf, addr, read_length, command,
+                                             (uint8_t *)&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_open(hdev);
+       if (ret) {
+               hid_err(hdev, "hw open failed\n");
+               return ret;
+       }
+       ret = hid_hw_power(hdev, PM_HINT_FULLON);
+       if (ret < 0) {
+               hid_err(hdev, "power management error: %d\n", ret);
+               goto hid_close;
+       }
+       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 (timeout = 0; timeout < XFER_TIMEOUT; ++timeout) {
+               ret = cp2112_xfer_status(dev);
+               if (-EBUSY == ret)
+                       continue;
+               if (ret < 0)
+                       goto power_normal;
+               break;
+       }
+       if (XFER_TIMEOUT <= timeout) {
+               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 = ntohs(*(uint16_t *)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_close:
+       hid_hw_close(hdev);
+       hid_dbg(hdev, "transfer finished: %d\n", ret);
+       return ret;
+}
+
+static uint32_t 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_probe(struct hid_device *hdev, const struct hid_device_id 
*id)
+{
+       struct cp2112_device *dev;
+       uint8_t buf[64];
+       struct cp2112_smbus_config *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 hid_stop;
+       }
+       ret = hid_hw_power(hdev, PM_HINT_FULLON);
+       if (ret < 0) {
+               hid_err(hdev, "power management error: %d\n", ret);
+               goto hid_close;
+       }
+       ret = cp2112_hid_get(hdev, CP2112_GET_VERSION_INFO, buf, 3,
+                            HID_FEATURE_REPORT);
+       if (ret != 3) {
+               hid_err(hdev, "error requesting version\n");
+               if (ret >= 0)
+                       ret = -EIO;
+               goto 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, buf,
+                            sizeof(*config) + 1, HID_FEATURE_REPORT);
+       if (ret != sizeof(*config) + 1) {
+               hid_err(hdev, "error requesting SMBus config\n");
+               if (ret >= 0)
+                       ret = -EIO;
+               goto power_normal;
+       }
+       config = (struct cp2112_smbus_config *)&buf[1];
+       config->retry_time = htons(1);
+       ret = cp2112_hid_output(hdev, buf, sizeof(*config) + 1,
+                               HID_FEATURE_REPORT);
+       if (ret != sizeof(*config) + 1) {
+               hid_err(hdev, "error setting SMBus config\n");
+               if (ret >= 0)
+                       ret = -EIO;
+               goto power_normal;
+       }
+       dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+       if (!dev) {
+               hid_err(hdev, "out of memory\n");
+               ret = -ENOMEM;
+               goto power_normal;
+       }
+       dev->hdev = hdev;
+       hid_set_drvdata(hdev, (void *)dev);
+       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);
+       hid_hw_power(hdev, PM_HINT_NORMAL);
+       hid_hw_close(hdev);
+       if (ret) {
+               hid_err(hdev, "error registering i2c adapter\n");
+               kfree(dev);
+               goto hid_stop;
+       }
+       hid_dbg(hdev, "adapter registered\n");
+       return ret;
+power_normal:
+       hid_hw_power(hdev, PM_HINT_NORMAL);
+hid_close:
+       hid_hw_close(hdev);
+hid_stop:
+       hid_hw_stop(hdev);
+       return ret;
+}
+
+static void cp2112_remove(struct hid_device *hdev)
+{
+       struct cp2112_device *dev = hid_get_drvdata(hdev);
+
+       hid_hw_stop(hdev);
+       i2c_del_adapter(&dev->adap);
+       kfree(dev);
+}
+
+static int cp2112_raw_event(struct hid_device *hdev, struct hid_report *report,
+                           uint8_t *data, int size)
+{
+       struct cp2112_device *dev = hid_get_drvdata(hdev);
+
+       switch (data[0]) {
+       case CP2112_TRANSFER_STATUS_RESPONSE:
+               hid_dbg(hdev, "xfer status: %02x %02x %04x %04x\n",
+                       data[1], data[2], htons(*(uint16_t *)&data[3]),
+                       htons(*(uint16_t *)&data[5]));
+               switch (data[1]) {
+               case STATUS0_IDLE:
+                       dev->xfer_status = -EAGAIN;
+                       break;
+               case STATUS0_BUSY:
+                       dev->xfer_status = -EBUSY;
+                       break;
+               case STATUS0_COMPLETE:
+                       dev->xfer_status = ntohs(*(uint16_t *)&data[5]);
+                       break;
+               case STATUS0_ERROR:
+                       switch (data[2]) {
+                       case STATUS1_TIMEOUT_NACK:
+                       case STATUS1_TIMEOUT_BUS:
+                               dev->xfer_status = -ETIMEDOUT;
+                               break;
+                       default:
+                               dev->xfer_status = -EIO;
+                       }
+                       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 <dbarksd...@uplogix.com>");
+MODULE_LICENSE("GPL");
+
diff --git a/drivers/hid/hid-ids.h b/drivers/hid/hid-ids.h
index ffe4c7a..3a9dd5d 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
-- 
tg: (584d88b..) upstream/hid-cp2112 (depends on: upstream/master)
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