Merge branch 'for-3.15/hid-cp2112' into for-3.15/hid-core-ll-transport-cleanup

5 files changed, 1080 insertions, 0 deletions

diff --git a/drivers/hid/Kconfig b/drivers/hid/Kconfig
index f7220011a00b..669cc19573ae 100644
--- a/drivers/hid/Kconfig
+++ b/drivers/hid/Kconfig
@@ -175,6 +175,15 @@ 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 && I2C && GPIOLIB
+        ---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 30e44318f87f..fc712dde02a4 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 0b57babe3f9f..ddb981db08bd 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -1732,6 +1732,7 @@ 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 000000000000..1025982c7fd3
--- /dev/null
+++ b/drivers/hid/hid-cp2112.c
@@ -0,0 +1,1068 @@
+/*
+ * 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 = hid_hw_raw_request(hdev, CP2112_GPIO_CONFIG, buf,
+                                       sizeof(buf), HID_FEATURE_REPORT,
+                                       HID_REQ_GET_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 = hid_hw_raw_request(hdev, CP2112_GPIO_GET, buf, sizeof(buf),
+                                       HID_FEATURE_REPORT, HID_REQ_GET_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 = hid_hw_raw_request(hdev, CP2112_GPIO_CONFIG, buf,
+                                       sizeof(buf), HID_FEATURE_REPORT,
+                                       HID_REQ_GET_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 = hid_hw_raw_request(hdev, report_number, buf, count,
+                                       report_type, HID_REQ_GET_REPORT);
+        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 %zd 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;
+        ssize_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 < %zd\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__); \
+} \
+static 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) \
+static 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 92b40c09d917..239f29c1c85c 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