282 lines
7.4 KiB
C
282 lines
7.4 KiB
C
/*
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* driver for the i2c-tiny-usb adapter - 1.0
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* http://www.harbaum.org/till/i2c_tiny_usb
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*
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* Copyright (C) 2006-2007 Till Harbaum (Till@Harbaum.org)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation, version 2.
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*
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*/
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/module.h>
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/* include interfaces to usb layer */
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#include <linux/usb.h>
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/* include interface to i2c layer */
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#include <linux/i2c.h>
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/* commands via USB, must match command ids in the firmware */
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#define CMD_ECHO 0
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#define CMD_GET_FUNC 1
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#define CMD_SET_DELAY 2
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#define CMD_GET_STATUS 3
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#define CMD_I2C_IO 4
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#define CMD_I2C_IO_BEGIN (1<<0)
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#define CMD_I2C_IO_END (1<<1)
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/* i2c bit delay, default is 10us -> 100kHz */
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static int delay = 10;
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module_param(delay, int, 0);
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MODULE_PARM_DESC(delay, "bit delay in microseconds, "
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"e.g. 10 for 100kHz (default is 100kHz)");
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static int usb_read(struct i2c_adapter *adapter, int cmd,
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int value, int index, void *data, int len);
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static int usb_write(struct i2c_adapter *adapter, int cmd,
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int value, int index, void *data, int len);
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/* ----- begin of i2c layer ---------------------------------------------- */
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#define STATUS_IDLE 0
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#define STATUS_ADDRESS_ACK 1
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#define STATUS_ADDRESS_NAK 2
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static int usb_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num)
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{
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unsigned char status;
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struct i2c_msg *pmsg;
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int i;
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dev_dbg(&adapter->dev, "master xfer %d messages:\n", num);
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for (i = 0 ; i < num ; i++) {
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int cmd = CMD_I2C_IO;
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if (i == 0)
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cmd |= CMD_I2C_IO_BEGIN;
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if (i == num-1)
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cmd |= CMD_I2C_IO_END;
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pmsg = &msgs[i];
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dev_dbg(&adapter->dev,
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" %d: %s (flags %d) %d bytes to 0x%02x\n",
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i, pmsg->flags & I2C_M_RD ? "read" : "write",
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pmsg->flags, pmsg->len, pmsg->addr);
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/* and directly send the message */
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if (pmsg->flags & I2C_M_RD) {
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/* read data */
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if (usb_read(adapter, cmd,
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pmsg->flags, pmsg->addr,
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pmsg->buf, pmsg->len) != pmsg->len) {
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dev_err(&adapter->dev,
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"failure reading data\n");
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return -EREMOTEIO;
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}
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} else {
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/* write data */
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if (usb_write(adapter, cmd,
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pmsg->flags, pmsg->addr,
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pmsg->buf, pmsg->len) != pmsg->len) {
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dev_err(&adapter->dev,
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"failure writing data\n");
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return -EREMOTEIO;
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}
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}
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/* read status */
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if (usb_read(adapter, CMD_GET_STATUS, 0, 0, &status, 1) != 1) {
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dev_err(&adapter->dev, "failure reading status\n");
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return -EREMOTEIO;
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}
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dev_dbg(&adapter->dev, " status = %d\n", status);
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if (status == STATUS_ADDRESS_NAK)
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return -EREMOTEIO;
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}
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return i;
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}
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static u32 usb_func(struct i2c_adapter *adapter)
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{
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u32 func;
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/* get functionality from adapter */
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if (usb_read(adapter, CMD_GET_FUNC, 0, 0, &func, sizeof(func)) !=
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sizeof(func)) {
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dev_err(&adapter->dev, "failure reading functionality\n");
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return 0;
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}
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return func;
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}
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/* This is the actual algorithm we define */
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static const struct i2c_algorithm usb_algorithm = {
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.master_xfer = usb_xfer,
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.functionality = usb_func,
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};
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/* ----- end of i2c layer ------------------------------------------------ */
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/* ----- begin of usb layer ---------------------------------------------- */
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/*
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* Initially the usb i2c interface uses a vid/pid pair donated by
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* Future Technology Devices International Ltd., later a pair was
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* bought from EZPrototypes
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*/
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static struct usb_device_id i2c_tiny_usb_table [] = {
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{ USB_DEVICE(0x0403, 0xc631) }, /* FTDI */
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{ USB_DEVICE(0x1c40, 0x0534) }, /* EZPrototypes */
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{ } /* Terminating entry */
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};
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MODULE_DEVICE_TABLE(usb, i2c_tiny_usb_table);
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/* Structure to hold all of our device specific stuff */
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struct i2c_tiny_usb {
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struct usb_device *usb_dev; /* the usb device for this device */
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struct usb_interface *interface; /* the interface for this device */
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struct i2c_adapter adapter; /* i2c related things */
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};
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static int usb_read(struct i2c_adapter *adapter, int cmd,
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int value, int index, void *data, int len)
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{
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struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data;
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/* do control transfer */
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return usb_control_msg(dev->usb_dev, usb_rcvctrlpipe(dev->usb_dev, 0),
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cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE |
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USB_DIR_IN, value, index, data, len, 2000);
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}
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static int usb_write(struct i2c_adapter *adapter, int cmd,
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int value, int index, void *data, int len)
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{
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struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data;
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/* do control transfer */
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return usb_control_msg(dev->usb_dev, usb_sndctrlpipe(dev->usb_dev, 0),
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cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
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value, index, data, len, 2000);
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}
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static void i2c_tiny_usb_free(struct i2c_tiny_usb *dev)
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{
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usb_put_dev(dev->usb_dev);
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kfree(dev);
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}
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static int i2c_tiny_usb_probe(struct usb_interface *interface,
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const struct usb_device_id *id)
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{
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struct i2c_tiny_usb *dev;
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int retval = -ENOMEM;
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u16 version;
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dev_dbg(&interface->dev, "probing usb device\n");
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/* allocate memory for our device state and initialize it */
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dev = kzalloc(sizeof(*dev), GFP_KERNEL);
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if (dev == NULL) {
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dev_err(&interface->dev, "Out of memory\n");
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goto error;
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}
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dev->usb_dev = usb_get_dev(interface_to_usbdev(interface));
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dev->interface = interface;
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/* save our data pointer in this interface device */
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usb_set_intfdata(interface, dev);
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version = le16_to_cpu(dev->usb_dev->descriptor.bcdDevice);
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dev_info(&interface->dev,
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"version %x.%02x found at bus %03d address %03d\n",
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version >> 8, version & 0xff,
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dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
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/* setup i2c adapter description */
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dev->adapter.owner = THIS_MODULE;
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dev->adapter.class = I2C_CLASS_HWMON;
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dev->adapter.algo = &usb_algorithm;
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dev->adapter.algo_data = dev;
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snprintf(dev->adapter.name, sizeof(dev->adapter.name),
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"i2c-tiny-usb at bus %03d device %03d",
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dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
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if (usb_write(&dev->adapter, CMD_SET_DELAY,
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cpu_to_le16(delay), 0, NULL, 0) != 0) {
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dev_err(&dev->adapter.dev,
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"failure setting delay to %dus\n", delay);
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retval = -EIO;
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goto error;
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}
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dev->adapter.dev.parent = &dev->interface->dev;
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/* and finally attach to i2c layer */
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i2c_add_adapter(&dev->adapter);
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/* inform user about successful attachment to i2c layer */
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dev_info(&dev->adapter.dev, "connected i2c-tiny-usb device\n");
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return 0;
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error:
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if (dev)
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i2c_tiny_usb_free(dev);
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return retval;
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}
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static void i2c_tiny_usb_disconnect(struct usb_interface *interface)
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{
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struct i2c_tiny_usb *dev = usb_get_intfdata(interface);
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i2c_del_adapter(&dev->adapter);
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usb_set_intfdata(interface, NULL);
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i2c_tiny_usb_free(dev);
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dev_dbg(&interface->dev, "disconnected\n");
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}
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static struct usb_driver i2c_tiny_usb_driver = {
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.name = "i2c-tiny-usb",
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.probe = i2c_tiny_usb_probe,
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.disconnect = i2c_tiny_usb_disconnect,
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.id_table = i2c_tiny_usb_table,
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};
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static int __init usb_i2c_tiny_usb_init(void)
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{
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/* register this driver with the USB subsystem */
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return usb_register(&i2c_tiny_usb_driver);
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}
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static void __exit usb_i2c_tiny_usb_exit(void)
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{
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/* deregister this driver with the USB subsystem */
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usb_deregister(&i2c_tiny_usb_driver);
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}
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module_init(usb_i2c_tiny_usb_init);
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module_exit(usb_i2c_tiny_usb_exit);
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/* ----- end of usb layer ------------------------------------------------ */
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MODULE_AUTHOR("Till Harbaum <Till@Harbaum.org>");
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MODULE_DESCRIPTION("i2c-tiny-usb driver v1.0");
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MODULE_LICENSE("GPL");
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