Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 787 insertions, 0 deletions

diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c
new file mode 100644
index 000000000..140dd074f
--- /dev/null
+++ b/drivers/i2c/i2c-dev.c
@@ -0,0 +1,787 @@
+/*
+    i2c-dev.c - i2c-bus driver, char device interface
+
+    Copyright (C) 1995-97 Simon G. Vogl
+    Copyright (C) 1998-99 Frodo Looijaard <frodol@dds.nl>
+    Copyright (C) 2003 Greg Kroah-Hartman <greg@kroah.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.
+*/
+
+/* Note that this is a complete rewrite of Simon Vogl's i2c-dev module.
+   But I have used so much of his original code and ideas that it seems
+   only fair to recognize him as co-author -- Frodo */
+
+/* The I2C_RDWR ioctl code is written by Kolja Waschk <waschk@telos.de> */
+
+#include <linux/cdev.h>
+#include <linux/device.h>
+#include <linux/fs.h>
+#include <linux/i2c-dev.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/jiffies.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/notifier.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/compat.h>
+
+/*
+ * An i2c_dev represents an i2c_adapter ... an I2C or SMBus master, not a
+ * slave (i2c_client) with which messages will be exchanged.  It's coupled
+ * with a character special file which is accessed by user mode drivers.
+ *
+ * The list of i2c_dev structures is parallel to the i2c_adapter lists
+ * maintained by the driver model, and is updated using bus notifications.
+ */
+struct i2c_dev {
+	struct list_head list;
+	struct i2c_adapter *adap;
+	struct device dev;
+	struct cdev cdev;
+};
+
+#define I2C_MINORS	MINORMASK
+static LIST_HEAD(i2c_dev_list);
+static DEFINE_SPINLOCK(i2c_dev_list_lock);
+
+static struct i2c_dev *i2c_dev_get_by_minor(unsigned index)
+{
+	struct i2c_dev *i2c_dev;
+
+	spin_lock(&i2c_dev_list_lock);
+	list_for_each_entry(i2c_dev, &i2c_dev_list, list) {
+		if (i2c_dev->adap->nr == index)
+			goto found;
+	}
+	i2c_dev = NULL;
+found:
+	spin_unlock(&i2c_dev_list_lock);
+	return i2c_dev;
+}
+
+static struct i2c_dev *get_free_i2c_dev(struct i2c_adapter *adap)
+{
+	struct i2c_dev *i2c_dev;
+
+	if (adap->nr >= I2C_MINORS) {
+		printk(KERN_ERR "i2c-dev: Out of device minors (%d)\n",
+		       adap->nr);
+		return ERR_PTR(-ENODEV);
+	}
+
+	i2c_dev = kzalloc(sizeof(*i2c_dev), GFP_KERNEL);
+	if (!i2c_dev)
+		return ERR_PTR(-ENOMEM);
+	i2c_dev->adap = adap;
+
+	spin_lock(&i2c_dev_list_lock);
+	list_add_tail(&i2c_dev->list, &i2c_dev_list);
+	spin_unlock(&i2c_dev_list_lock);
+	return i2c_dev;
+}
+
+static void put_i2c_dev(struct i2c_dev *i2c_dev, bool del_cdev)
+{
+	spin_lock(&i2c_dev_list_lock);
+	list_del(&i2c_dev->list);
+	spin_unlock(&i2c_dev_list_lock);
+	if (del_cdev)
+		cdev_device_del(&i2c_dev->cdev, &i2c_dev->dev);
+	put_device(&i2c_dev->dev);
+}
+
+static ssize_t name_show(struct device *dev,
+			 struct device_attribute *attr, char *buf)
+{
+	struct i2c_dev *i2c_dev = i2c_dev_get_by_minor(MINOR(dev->devt));
+
+	if (!i2c_dev)
+		return -ENODEV;
+	return sprintf(buf, "%s\n", i2c_dev->adap->name);
+}
+static DEVICE_ATTR_RO(name);
+
+static struct attribute *i2c_attrs[] = {
+	&dev_attr_name.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(i2c);
+
+/* ------------------------------------------------------------------------- */
+
+/*
+ * After opening an instance of this character special file, a file
+ * descriptor starts out associated only with an i2c_adapter (and bus).
+ *
+ * Using the I2C_RDWR ioctl(), you can then *immediately* issue i2c_msg
+ * traffic to any devices on the bus used by that adapter.  That's because
+ * the i2c_msg vectors embed all the addressing information they need, and
+ * are submitted directly to an i2c_adapter.  However, SMBus-only adapters
+ * don't support that interface.
+ *
+ * To use read()/write() system calls on that file descriptor, or to use
+ * SMBus interfaces (and work with SMBus-only hosts!), you must first issue
+ * an I2C_SLAVE (or I2C_SLAVE_FORCE) ioctl.  That configures an anonymous
+ * (never registered) i2c_client so it holds the addressing information
+ * needed by those system calls and by this SMBus interface.
+ */
+
+static ssize_t i2cdev_read(struct file *file, char __user *buf, size_t count,
+		loff_t *offset)
+{
+	char *tmp;
+	int ret;
+
+	struct i2c_client *client = file->private_data;
+
+	if (count > 8192)
+		count = 8192;
+
+	tmp = kzalloc(count, GFP_KERNEL);
+	if (tmp == NULL)
+		return -ENOMEM;
+
+	pr_debug("i2c-dev: i2c-%d reading %zu bytes.\n",
+		iminor(file_inode(file)), count);
+
+	ret = i2c_master_recv(client, tmp, count);
+	if (ret >= 0)
+		if (copy_to_user(buf, tmp, ret))
+			ret = -EFAULT;
+	kfree(tmp);
+	return ret;
+}
+
+static ssize_t i2cdev_write(struct file *file, const char __user *buf,
+		size_t count, loff_t *offset)
+{
+	int ret;
+	char *tmp;
+	struct i2c_client *client = file->private_data;
+
+	if (count > 8192)
+		count = 8192;
+
+	tmp = memdup_user(buf, count);
+	if (IS_ERR(tmp))
+		return PTR_ERR(tmp);
+
+	pr_debug("i2c-dev: i2c-%d writing %zu bytes.\n",
+		iminor(file_inode(file)), count);
+
+	ret = i2c_master_send(client, tmp, count);
+	kfree(tmp);
+	return ret;
+}
+
+static int i2cdev_check(struct device *dev, void *addrp)
+{
+	struct i2c_client *client = i2c_verify_client(dev);
+
+	if (!client || client->addr != *(unsigned int *)addrp)
+		return 0;
+
+	return dev->driver ? -EBUSY : 0;
+}
+
+/* walk up mux tree */
+static int i2cdev_check_mux_parents(struct i2c_adapter *adapter, int addr)
+{
+	struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
+	int result;
+
+	result = device_for_each_child(&adapter->dev, &addr, i2cdev_check);
+	if (!result && parent)
+		result = i2cdev_check_mux_parents(parent, addr);
+
+	return result;
+}
+
+/* recurse down mux tree */
+static int i2cdev_check_mux_children(struct device *dev, void *addrp)
+{
+	int result;
+
+	if (dev->type == &i2c_adapter_type)
+		result = device_for_each_child(dev, addrp,
+						i2cdev_check_mux_children);
+	else
+		result = i2cdev_check(dev, addrp);
+
+	return result;
+}
+
+/* This address checking function differs from the one in i2c-core
+   in that it considers an address with a registered device, but no
+   driver bound to it, as NOT busy. */
+static int i2cdev_check_addr(struct i2c_adapter *adapter, unsigned int addr)
+{
+	struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
+	int result = 0;
+
+	if (parent)
+		result = i2cdev_check_mux_parents(parent, addr);
+
+	if (!result)
+		result = device_for_each_child(&adapter->dev, &addr,
+						i2cdev_check_mux_children);
+
+	return result;
+}
+
+static noinline int i2cdev_ioctl_rdwr(struct i2c_client *client,
+		unsigned nmsgs, struct i2c_msg *msgs)
+{
+	u8 __user **data_ptrs;
+	int i, res;
+
+	data_ptrs = kmalloc_array(nmsgs, sizeof(u8 __user *), GFP_KERNEL);
+	if (data_ptrs == NULL) {
+		kfree(msgs);
+		return -ENOMEM;
+	}
+
+	res = 0;
+	for (i = 0; i < nmsgs; i++) {
+		/* Limit the size of the message to a sane amount */
+		if (msgs[i].len > 8192) {
+			res = -EINVAL;
+			break;
+		}
+
+		data_ptrs[i] = (u8 __user *)msgs[i].buf;
+		msgs[i].buf = memdup_user(data_ptrs[i], msgs[i].len);
+		if (IS_ERR(msgs[i].buf)) {
+			res = PTR_ERR(msgs[i].buf);
+			break;
+		}
+		/* memdup_user allocates with GFP_KERNEL, so DMA is ok */
+		msgs[i].flags |= I2C_M_DMA_SAFE;
+
+		/*
+		 * If the message length is received from the slave (similar
+		 * to SMBus block read), we must ensure that the buffer will
+		 * be large enough to cope with a message length of
+		 * I2C_SMBUS_BLOCK_MAX as this is the maximum underlying bus
+		 * drivers allow. The first byte in the buffer must be
+		 * pre-filled with the number of extra bytes, which must be
+		 * at least one to hold the message length, but can be
+		 * greater (for example to account for a checksum byte at
+		 * the end of the message.)
+		 */
+		if (msgs[i].flags & I2C_M_RECV_LEN) {
+			if (!(msgs[i].flags & I2C_M_RD) ||
+			    msgs[i].len < 1 || msgs[i].buf[0] < 1 ||
+			    msgs[i].len < msgs[i].buf[0] +
+					     I2C_SMBUS_BLOCK_MAX) {
+				i++;
+				res = -EINVAL;
+				break;
+			}
+
+			msgs[i].len = msgs[i].buf[0];
+		}
+	}
+	if (res < 0) {
+		int j;
+		for (j = 0; j < i; ++j)
+			kfree(msgs[j].buf);
+		kfree(data_ptrs);
+		kfree(msgs);
+		return res;
+	}
+
+	res = i2c_transfer(client->adapter, msgs, nmsgs);
+	while (i-- > 0) {
+		if (res >= 0 && (msgs[i].flags & I2C_M_RD)) {
+			if (copy_to_user(data_ptrs[i], msgs[i].buf,
+					 msgs[i].len))
+				res = -EFAULT;
+		}
+		kfree(msgs[i].buf);
+	}
+	kfree(data_ptrs);
+	kfree(msgs);
+	return res;
+}
+
+static noinline int i2cdev_ioctl_smbus(struct i2c_client *client,
+		u8 read_write, u8 command, u32 size,
+		union i2c_smbus_data __user *data)
+{
+	union i2c_smbus_data temp = {};
+	int datasize, res;
+
+	if ((size != I2C_SMBUS_BYTE) &&
+	    (size != I2C_SMBUS_QUICK) &&
+	    (size != I2C_SMBUS_BYTE_DATA) &&
+	    (size != I2C_SMBUS_WORD_DATA) &&
+	    (size != I2C_SMBUS_PROC_CALL) &&
+	    (size != I2C_SMBUS_BLOCK_DATA) &&
+	    (size != I2C_SMBUS_I2C_BLOCK_BROKEN) &&
+	    (size != I2C_SMBUS_I2C_BLOCK_DATA) &&
+	    (size != I2C_SMBUS_BLOCK_PROC_CALL)) {
+		dev_dbg(&client->adapter->dev,
+			"size out of range (%x) in ioctl I2C_SMBUS.\n",
+			size);
+		return -EINVAL;
+	}
+	/* Note that I2C_SMBUS_READ and I2C_SMBUS_WRITE are 0 and 1,
+	   so the check is valid if size==I2C_SMBUS_QUICK too. */
+	if ((read_write != I2C_SMBUS_READ) &&
+	    (read_write != I2C_SMBUS_WRITE)) {
+		dev_dbg(&client->adapter->dev,
+			"read_write out of range (%x) in ioctl I2C_SMBUS.\n",
+			read_write);
+		return -EINVAL;
+	}
+
+	/* Note that command values are always valid! */
+
+	if ((size == I2C_SMBUS_QUICK) ||
+	    ((size == I2C_SMBUS_BYTE) &&
+	    (read_write == I2C_SMBUS_WRITE)))
+		/* These are special: we do not use data */
+		return i2c_smbus_xfer(client->adapter, client->addr,
+				      client->flags, read_write,
+				      command, size, NULL);
+
+	if (data == NULL) {
+		dev_dbg(&client->adapter->dev,
+			"data is NULL pointer in ioctl I2C_SMBUS.\n");
+		return -EINVAL;
+	}
+
+	if ((size == I2C_SMBUS_BYTE_DATA) ||
+	    (size == I2C_SMBUS_BYTE))
+		datasize = sizeof(data->byte);
+	else if ((size == I2C_SMBUS_WORD_DATA) ||
+		 (size == I2C_SMBUS_PROC_CALL))
+		datasize = sizeof(data->word);
+	else /* size == smbus block, i2c block, or block proc. call */
+		datasize = sizeof(data->block);
+
+	if ((size == I2C_SMBUS_PROC_CALL) ||
+	    (size == I2C_SMBUS_BLOCK_PROC_CALL) ||
+	    (size == I2C_SMBUS_I2C_BLOCK_DATA) ||
+	    (read_write == I2C_SMBUS_WRITE)) {
+		if (copy_from_user(&temp, data, datasize))
+			return -EFAULT;
+	}
+	if (size == I2C_SMBUS_I2C_BLOCK_BROKEN) {
+		/* Convert old I2C block commands to the new
+		   convention. This preserves binary compatibility. */
+		size = I2C_SMBUS_I2C_BLOCK_DATA;
+		if (read_write == I2C_SMBUS_READ)
+			temp.block[0] = I2C_SMBUS_BLOCK_MAX;
+	}
+	res = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
+	      read_write, command, size, &temp);
+	if (!res && ((size == I2C_SMBUS_PROC_CALL) ||
+		     (size == I2C_SMBUS_BLOCK_PROC_CALL) ||
+		     (read_write == I2C_SMBUS_READ))) {
+		if (copy_to_user(data, &temp, datasize))
+			return -EFAULT;
+	}
+	return res;
+}
+
+static long i2cdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	struct i2c_client *client = file->private_data;
+	unsigned long funcs;
+
+	dev_dbg(&client->adapter->dev, "ioctl, cmd=0x%02x, arg=0x%02lx\n",
+		cmd, arg);
+
+	switch (cmd) {
+	case I2C_SLAVE:
+	case I2C_SLAVE_FORCE:
+		if ((arg > 0x3ff) ||
+		    (((client->flags & I2C_M_TEN) == 0) && arg > 0x7f))
+			return -EINVAL;
+		if (cmd == I2C_SLAVE && i2cdev_check_addr(client->adapter, arg))
+			return -EBUSY;
+		/* REVISIT: address could become busy later */
+		client->addr = arg;
+		return 0;
+	case I2C_TENBIT:
+		if (arg)
+			client->flags |= I2C_M_TEN;
+		else
+			client->flags &= ~I2C_M_TEN;
+		return 0;
+	case I2C_PEC:
+		/*
+		 * Setting the PEC flag here won't affect kernel drivers,
+		 * which will be using the i2c_client node registered with
+		 * the driver model core.  Likewise, when that client has
+		 * the PEC flag already set, the i2c-dev driver won't see
+		 * (or use) this setting.
+		 */
+		if (arg)
+			client->flags |= I2C_CLIENT_PEC;
+		else
+			client->flags &= ~I2C_CLIENT_PEC;
+		return 0;
+	case I2C_FUNCS:
+		funcs = i2c_get_functionality(client->adapter);
+		return put_user(funcs, (unsigned long __user *)arg);
+
+	case I2C_RDWR: {
+		struct i2c_rdwr_ioctl_data rdwr_arg;
+		struct i2c_msg *rdwr_pa;
+
+		if (copy_from_user(&rdwr_arg,
+				   (struct i2c_rdwr_ioctl_data __user *)arg,
+				   sizeof(rdwr_arg)))
+			return -EFAULT;
+
+		if (!rdwr_arg.msgs || rdwr_arg.nmsgs == 0)
+			return -EINVAL;
+
+		/*
+		 * Put an arbitrary limit on the number of messages that can
+		 * be sent at once
+		 */
+		if (rdwr_arg.nmsgs > I2C_RDWR_IOCTL_MAX_MSGS)
+			return -EINVAL;
+
+		rdwr_pa = memdup_user(rdwr_arg.msgs,
+				      rdwr_arg.nmsgs * sizeof(struct i2c_msg));
+		if (IS_ERR(rdwr_pa))
+			return PTR_ERR(rdwr_pa);
+
+		return i2cdev_ioctl_rdwr(client, rdwr_arg.nmsgs, rdwr_pa);
+	}
+
+	case I2C_SMBUS: {
+		struct i2c_smbus_ioctl_data data_arg;
+		if (copy_from_user(&data_arg,
+				   (struct i2c_smbus_ioctl_data __user *) arg,
+				   sizeof(struct i2c_smbus_ioctl_data)))
+			return -EFAULT;
+		return i2cdev_ioctl_smbus(client, data_arg.read_write,
+					  data_arg.command,
+					  data_arg.size,
+					  data_arg.data);
+	}
+	case I2C_RETRIES:
+		if (arg > INT_MAX)
+			return -EINVAL;
+
+		client->adapter->retries = arg;
+		break;
+	case I2C_TIMEOUT:
+		if (arg > INT_MAX)
+			return -EINVAL;
+
+		/* For historical reasons, user-space sets the timeout
+		 * value in units of 10 ms.
+		 */
+		client->adapter->timeout = msecs_to_jiffies(arg * 10);
+		break;
+	default:
+		/* NOTE:  returning a fault code here could cause trouble
+		 * in buggy userspace code.  Some old kernel bugs returned
+		 * zero in this case, and userspace code might accidentally
+		 * have depended on that bug.
+		 */
+		return -ENOTTY;
+	}
+	return 0;
+}
+
+#ifdef CONFIG_COMPAT
+
+struct i2c_smbus_ioctl_data32 {
+	u8 read_write;
+	u8 command;
+	u32 size;
+	compat_caddr_t data; /* union i2c_smbus_data *data */
+};
+
+struct i2c_msg32 {
+	u16 addr;
+	u16 flags;
+	u16 len;
+	compat_caddr_t buf;
+};
+
+struct i2c_rdwr_ioctl_data32 {
+	compat_caddr_t msgs; /* struct i2c_msg __user *msgs */
+	u32 nmsgs;
+};
+
+static long compat_i2cdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	struct i2c_client *client = file->private_data;
+	unsigned long funcs;
+	switch (cmd) {
+	case I2C_FUNCS:
+		funcs = i2c_get_functionality(client->adapter);
+		return put_user(funcs, (compat_ulong_t __user *)arg);
+	case I2C_RDWR: {
+		struct i2c_rdwr_ioctl_data32 rdwr_arg;
+		struct i2c_msg32 *p;
+		struct i2c_msg *rdwr_pa;
+		int i;
+
+		if (copy_from_user(&rdwr_arg,
+				   (struct i2c_rdwr_ioctl_data32 __user *)arg,
+				   sizeof(rdwr_arg)))
+			return -EFAULT;
+
+		if (!rdwr_arg.msgs || rdwr_arg.nmsgs == 0)
+			return -EINVAL;
+
+		if (rdwr_arg.nmsgs > I2C_RDWR_IOCTL_MAX_MSGS)
+			return -EINVAL;
+
+		rdwr_pa = kmalloc_array(rdwr_arg.nmsgs, sizeof(struct i2c_msg),
+				      GFP_KERNEL);
+		if (!rdwr_pa)
+			return -ENOMEM;
+
+		p = compat_ptr(rdwr_arg.msgs);
+		for (i = 0; i < rdwr_arg.nmsgs; i++) {
+			struct i2c_msg32 umsg;
+			if (copy_from_user(&umsg, p + i, sizeof(umsg))) {
+				kfree(rdwr_pa);
+				return -EFAULT;
+			}
+			rdwr_pa[i] = (struct i2c_msg) {
+				.addr = umsg.addr,
+				.flags = umsg.flags,
+				.len = umsg.len,
+				.buf = compat_ptr(umsg.buf)
+			};
+		}
+
+		return i2cdev_ioctl_rdwr(client, rdwr_arg.nmsgs, rdwr_pa);
+	}
+	case I2C_SMBUS: {
+		struct i2c_smbus_ioctl_data32	data32;
+		if (copy_from_user(&data32,
+				   (void __user *) arg,
+				   sizeof(data32)))
+			return -EFAULT;
+		return i2cdev_ioctl_smbus(client, data32.read_write,
+					  data32.command,
+					  data32.size,
+					  compat_ptr(data32.data));
+	}
+	default:
+		return i2cdev_ioctl(file, cmd, arg);
+	}
+}
+#else
+#define compat_i2cdev_ioctl NULL
+#endif
+
+static int i2cdev_open(struct inode *inode, struct file *file)
+{
+	unsigned int minor = iminor(inode);
+	struct i2c_client *client;
+	struct i2c_adapter *adap;
+
+	adap = i2c_get_adapter(minor);
+	if (!adap)
+		return -ENODEV;
+
+	/* This creates an anonymous i2c_client, which may later be
+	 * pointed to some address using I2C_SLAVE or I2C_SLAVE_FORCE.
+	 *
+	 * This client is ** NEVER REGISTERED ** with the driver model
+	 * or I2C core code!!  It just holds private copies of addressing
+	 * information and maybe a PEC flag.
+	 */
+	client = kzalloc(sizeof(*client), GFP_KERNEL);
+	if (!client) {
+		i2c_put_adapter(adap);
+		return -ENOMEM;
+	}
+	snprintf(client->name, I2C_NAME_SIZE, "i2c-dev %d", adap->nr);
+
+	client->adapter = adap;
+	file->private_data = client;
+
+	return 0;
+}
+
+static int i2cdev_release(struct inode *inode, struct file *file)
+{
+	struct i2c_client *client = file->private_data;
+
+	i2c_put_adapter(client->adapter);
+	kfree(client);
+	file->private_data = NULL;
+
+	return 0;
+}
+
+static const struct file_operations i2cdev_fops = {
+	.owner		= THIS_MODULE,
+	.llseek		= no_llseek,
+	.read		= i2cdev_read,
+	.write		= i2cdev_write,
+	.unlocked_ioctl	= i2cdev_ioctl,
+	.compat_ioctl	= compat_i2cdev_ioctl,
+	.open		= i2cdev_open,
+	.release	= i2cdev_release,
+};
+
+/* ------------------------------------------------------------------------- */
+
+static struct class *i2c_dev_class;
+
+static void i2cdev_dev_release(struct device *dev)
+{
+	struct i2c_dev *i2c_dev;
+
+	i2c_dev = container_of(dev, struct i2c_dev, dev);
+	kfree(i2c_dev);
+}
+
+static int i2cdev_attach_adapter(struct device *dev, void *dummy)
+{
+	struct i2c_adapter *adap;
+	struct i2c_dev *i2c_dev;
+	int res;
+
+	if (dev->type != &i2c_adapter_type)
+		return 0;
+	adap = to_i2c_adapter(dev);
+
+	i2c_dev = get_free_i2c_dev(adap);
+	if (IS_ERR(i2c_dev))
+		return PTR_ERR(i2c_dev);
+
+	cdev_init(&i2c_dev->cdev, &i2cdev_fops);
+	i2c_dev->cdev.owner = THIS_MODULE;
+
+	device_initialize(&i2c_dev->dev);
+	i2c_dev->dev.devt = MKDEV(I2C_MAJOR, adap->nr);
+	i2c_dev->dev.class = i2c_dev_class;
+	i2c_dev->dev.parent = &adap->dev;
+	i2c_dev->dev.release = i2cdev_dev_release;
+	dev_set_name(&i2c_dev->dev, "i2c-%d", adap->nr);
+
+	res = cdev_device_add(&i2c_dev->cdev, &i2c_dev->dev);
+	if (res) {
+		put_i2c_dev(i2c_dev, false);
+		return res;
+	}
+
+	pr_debug("i2c-dev: adapter [%s] registered as minor %d\n",
+		 adap->name, adap->nr);
+	return 0;
+}
+
+static int i2cdev_detach_adapter(struct device *dev, void *dummy)
+{
+	struct i2c_adapter *adap;
+	struct i2c_dev *i2c_dev;
+
+	if (dev->type != &i2c_adapter_type)
+		return 0;
+	adap = to_i2c_adapter(dev);
+
+	i2c_dev = i2c_dev_get_by_minor(adap->nr);
+	if (!i2c_dev) /* attach_adapter must have failed */
+		return 0;
+
+	put_i2c_dev(i2c_dev, true);
+
+	pr_debug("i2c-dev: adapter [%s] unregistered\n", adap->name);
+	return 0;
+}
+
+static int i2cdev_notifier_call(struct notifier_block *nb, unsigned long action,
+			 void *data)
+{
+	struct device *dev = data;
+
+	switch (action) {
+	case BUS_NOTIFY_ADD_DEVICE:
+		return i2cdev_attach_adapter(dev, NULL);
+	case BUS_NOTIFY_DEL_DEVICE:
+		return i2cdev_detach_adapter(dev, NULL);
+	}
+
+	return 0;
+}
+
+static struct notifier_block i2cdev_notifier = {
+	.notifier_call = i2cdev_notifier_call,
+};
+
+/* ------------------------------------------------------------------------- */
+
+/*
+ * module load/unload record keeping
+ */
+
+static int __init i2c_dev_init(void)
+{
+	int res;
+
+	printk(KERN_INFO "i2c /dev entries driver\n");
+
+	res = register_chrdev_region(MKDEV(I2C_MAJOR, 0), I2C_MINORS, "i2c");
+	if (res)
+		goto out;
+
+	i2c_dev_class = class_create(THIS_MODULE, "i2c-dev");
+	if (IS_ERR(i2c_dev_class)) {
+		res = PTR_ERR(i2c_dev_class);
+		goto out_unreg_chrdev;
+	}
+	i2c_dev_class->dev_groups = i2c_groups;
+
+	/* Keep track of adapters which will be added or removed later */
+	res = bus_register_notifier(&i2c_bus_type, &i2cdev_notifier);
+	if (res)
+		goto out_unreg_class;
+
+	/* Bind to already existing adapters right away */
+	i2c_for_each_dev(NULL, i2cdev_attach_adapter);
+
+	return 0;
+
+out_unreg_class:
+	class_destroy(i2c_dev_class);
+out_unreg_chrdev:
+	unregister_chrdev_region(MKDEV(I2C_MAJOR, 0), I2C_MINORS);
+out:
+	printk(KERN_ERR "%s: Driver Initialisation failed\n", __FILE__);
+	return res;
+}
+
+static void __exit i2c_dev_exit(void)
+{
+	bus_unregister_notifier(&i2c_bus_type, &i2cdev_notifier);
+	i2c_for_each_dev(NULL, i2cdev_detach_adapter);
+	class_destroy(i2c_dev_class);
+	unregister_chrdev_region(MKDEV(I2C_MAJOR, 0), I2C_MINORS);
+}
+
+MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and "
+		"Simon G. Vogl <simon@tk.uni-linz.ac.at>");
+MODULE_DESCRIPTION("I2C /dev entries driver");
+MODULE_LICENSE("GPL");
+
+module_init(i2c_dev_init);
+module_exit(i2c_dev_exit);