xref: /openbmc/linux/drivers/i2c/i2c-dev.c (revision cf3ee3c8)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3     i2c-dev.c - i2c-bus driver, char device interface
4 
5     Copyright (C) 1995-97 Simon G. Vogl
6     Copyright (C) 1998-99 Frodo Looijaard <frodol@dds.nl>
7     Copyright (C) 2003 Greg Kroah-Hartman <greg@kroah.com>
8 
9 */
10 
11 /* Note that this is a complete rewrite of Simon Vogl's i2c-dev module.
12    But I have used so much of his original code and ideas that it seems
13    only fair to recognize him as co-author -- Frodo */
14 
15 /* The I2C_RDWR ioctl code is written by Kolja Waschk <waschk@telos.de> */
16 
17 #include <linux/cdev.h>
18 #include <linux/compat.h>
19 #include <linux/device.h>
20 #include <linux/fs.h>
21 #include <linux/i2c-dev.h>
22 #include <linux/i2c.h>
23 #include <linux/init.h>
24 #include <linux/jiffies.h>
25 #include <linux/kernel.h>
26 #include <linux/list.h>
27 #include <linux/module.h>
28 #include <linux/notifier.h>
29 #include <linux/slab.h>
30 #include <linux/uaccess.h>
31 
32 /*
33  * An i2c_dev represents an i2c_adapter ... an I2C or SMBus master, not a
34  * slave (i2c_client) with which messages will be exchanged.  It's coupled
35  * with a character special file which is accessed by user mode drivers.
36  *
37  * The list of i2c_dev structures is parallel to the i2c_adapter lists
38  * maintained by the driver model, and is updated using bus notifications.
39  */
40 struct i2c_dev {
41 	struct list_head list;
42 	struct i2c_adapter *adap;
43 	struct device dev;
44 	struct cdev cdev;
45 };
46 
47 #define I2C_MINORS	(MINORMASK + 1)
48 static LIST_HEAD(i2c_dev_list);
49 static DEFINE_SPINLOCK(i2c_dev_list_lock);
50 
51 static struct i2c_dev *i2c_dev_get_by_minor(unsigned index)
52 {
53 	struct i2c_dev *i2c_dev;
54 
55 	spin_lock(&i2c_dev_list_lock);
56 	list_for_each_entry(i2c_dev, &i2c_dev_list, list) {
57 		if (i2c_dev->adap->nr == index)
58 			goto found;
59 	}
60 	i2c_dev = NULL;
61 found:
62 	spin_unlock(&i2c_dev_list_lock);
63 	return i2c_dev;
64 }
65 
66 static struct i2c_dev *get_free_i2c_dev(struct i2c_adapter *adap)
67 {
68 	struct i2c_dev *i2c_dev;
69 
70 	if (adap->nr >= I2C_MINORS) {
71 		printk(KERN_ERR "i2c-dev: Out of device minors (%d)\n",
72 		       adap->nr);
73 		return ERR_PTR(-ENODEV);
74 	}
75 
76 	i2c_dev = kzalloc(sizeof(*i2c_dev), GFP_KERNEL);
77 	if (!i2c_dev)
78 		return ERR_PTR(-ENOMEM);
79 	i2c_dev->adap = adap;
80 
81 	spin_lock(&i2c_dev_list_lock);
82 	list_add_tail(&i2c_dev->list, &i2c_dev_list);
83 	spin_unlock(&i2c_dev_list_lock);
84 	return i2c_dev;
85 }
86 
87 static void put_i2c_dev(struct i2c_dev *i2c_dev, bool del_cdev)
88 {
89 	spin_lock(&i2c_dev_list_lock);
90 	list_del(&i2c_dev->list);
91 	spin_unlock(&i2c_dev_list_lock);
92 	if (del_cdev)
93 		cdev_device_del(&i2c_dev->cdev, &i2c_dev->dev);
94 	put_device(&i2c_dev->dev);
95 }
96 
97 static ssize_t name_show(struct device *dev,
98 			 struct device_attribute *attr, char *buf)
99 {
100 	struct i2c_dev *i2c_dev = i2c_dev_get_by_minor(MINOR(dev->devt));
101 
102 	if (!i2c_dev)
103 		return -ENODEV;
104 	return sprintf(buf, "%s\n", i2c_dev->adap->name);
105 }
106 static DEVICE_ATTR_RO(name);
107 
108 static struct attribute *i2c_attrs[] = {
109 	&dev_attr_name.attr,
110 	NULL,
111 };
112 ATTRIBUTE_GROUPS(i2c);
113 
114 /* ------------------------------------------------------------------------- */
115 
116 /*
117  * After opening an instance of this character special file, a file
118  * descriptor starts out associated only with an i2c_adapter (and bus).
119  *
120  * Using the I2C_RDWR ioctl(), you can then *immediately* issue i2c_msg
121  * traffic to any devices on the bus used by that adapter.  That's because
122  * the i2c_msg vectors embed all the addressing information they need, and
123  * are submitted directly to an i2c_adapter.  However, SMBus-only adapters
124  * don't support that interface.
125  *
126  * To use read()/write() system calls on that file descriptor, or to use
127  * SMBus interfaces (and work with SMBus-only hosts!), you must first issue
128  * an I2C_SLAVE (or I2C_SLAVE_FORCE) ioctl.  That configures an anonymous
129  * (never registered) i2c_client so it holds the addressing information
130  * needed by those system calls and by this SMBus interface.
131  */
132 
133 static ssize_t i2cdev_read(struct file *file, char __user *buf, size_t count,
134 		loff_t *offset)
135 {
136 	char *tmp;
137 	int ret;
138 
139 	struct i2c_client *client = file->private_data;
140 
141 	if (count > 8192)
142 		count = 8192;
143 
144 	tmp = kmalloc(count, GFP_KERNEL);
145 	if (tmp == NULL)
146 		return -ENOMEM;
147 
148 	pr_debug("i2c-dev: i2c-%d reading %zu bytes.\n",
149 		iminor(file_inode(file)), count);
150 
151 	ret = i2c_master_recv(client, tmp, count);
152 	if (ret >= 0)
153 		ret = copy_to_user(buf, tmp, count) ? -EFAULT : ret;
154 	kfree(tmp);
155 	return ret;
156 }
157 
158 static ssize_t i2cdev_write(struct file *file, const char __user *buf,
159 		size_t count, loff_t *offset)
160 {
161 	int ret;
162 	char *tmp;
163 	struct i2c_client *client = file->private_data;
164 
165 	if (count > 8192)
166 		count = 8192;
167 
168 	tmp = memdup_user(buf, count);
169 	if (IS_ERR(tmp))
170 		return PTR_ERR(tmp);
171 
172 	pr_debug("i2c-dev: i2c-%d writing %zu bytes.\n",
173 		iminor(file_inode(file)), count);
174 
175 	ret = i2c_master_send(client, tmp, count);
176 	kfree(tmp);
177 	return ret;
178 }
179 
180 static int i2cdev_check(struct device *dev, void *addrp)
181 {
182 	struct i2c_client *client = i2c_verify_client(dev);
183 
184 	if (!client || client->addr != *(unsigned int *)addrp)
185 		return 0;
186 
187 	return dev->driver ? -EBUSY : 0;
188 }
189 
190 /* walk up mux tree */
191 static int i2cdev_check_mux_parents(struct i2c_adapter *adapter, int addr)
192 {
193 	struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
194 	int result;
195 
196 	result = device_for_each_child(&adapter->dev, &addr, i2cdev_check);
197 	if (!result && parent)
198 		result = i2cdev_check_mux_parents(parent, addr);
199 
200 	return result;
201 }
202 
203 /* recurse down mux tree */
204 static int i2cdev_check_mux_children(struct device *dev, void *addrp)
205 {
206 	int result;
207 
208 	if (dev->type == &i2c_adapter_type)
209 		result = device_for_each_child(dev, addrp,
210 						i2cdev_check_mux_children);
211 	else
212 		result = i2cdev_check(dev, addrp);
213 
214 	return result;
215 }
216 
217 /* This address checking function differs from the one in i2c-core
218    in that it considers an address with a registered device, but no
219    driver bound to it, as NOT busy. */
220 static int i2cdev_check_addr(struct i2c_adapter *adapter, unsigned int addr)
221 {
222 	struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
223 	int result = 0;
224 
225 	if (parent)
226 		result = i2cdev_check_mux_parents(parent, addr);
227 
228 	if (!result)
229 		result = device_for_each_child(&adapter->dev, &addr,
230 						i2cdev_check_mux_children);
231 
232 	return result;
233 }
234 
235 static noinline int i2cdev_ioctl_rdwr(struct i2c_client *client,
236 		unsigned nmsgs, struct i2c_msg *msgs)
237 {
238 	u8 __user **data_ptrs;
239 	int i, res;
240 
241 	data_ptrs = kmalloc_array(nmsgs, sizeof(u8 __user *), GFP_KERNEL);
242 	if (data_ptrs == NULL) {
243 		kfree(msgs);
244 		return -ENOMEM;
245 	}
246 
247 	res = 0;
248 	for (i = 0; i < nmsgs; i++) {
249 		/* Limit the size of the message to a sane amount */
250 		if (msgs[i].len > 8192) {
251 			res = -EINVAL;
252 			break;
253 		}
254 
255 		data_ptrs[i] = (u8 __user *)msgs[i].buf;
256 		msgs[i].buf = memdup_user(data_ptrs[i], msgs[i].len);
257 		if (IS_ERR(msgs[i].buf)) {
258 			res = PTR_ERR(msgs[i].buf);
259 			break;
260 		}
261 		/* memdup_user allocates with GFP_KERNEL, so DMA is ok */
262 		msgs[i].flags |= I2C_M_DMA_SAFE;
263 
264 		/*
265 		 * If the message length is received from the slave (similar
266 		 * to SMBus block read), we must ensure that the buffer will
267 		 * be large enough to cope with a message length of
268 		 * I2C_SMBUS_BLOCK_MAX as this is the maximum underlying bus
269 		 * drivers allow. The first byte in the buffer must be
270 		 * pre-filled with the number of extra bytes, which must be
271 		 * at least one to hold the message length, but can be
272 		 * greater (for example to account for a checksum byte at
273 		 * the end of the message.)
274 		 */
275 		if (msgs[i].flags & I2C_M_RECV_LEN) {
276 			if (!(msgs[i].flags & I2C_M_RD) ||
277 			    msgs[i].len < 1 || msgs[i].buf[0] < 1 ||
278 			    msgs[i].len < msgs[i].buf[0] +
279 					     I2C_SMBUS_BLOCK_MAX) {
280 				i++;
281 				res = -EINVAL;
282 				break;
283 			}
284 
285 			msgs[i].len = msgs[i].buf[0];
286 		}
287 	}
288 	if (res < 0) {
289 		int j;
290 		for (j = 0; j < i; ++j)
291 			kfree(msgs[j].buf);
292 		kfree(data_ptrs);
293 		kfree(msgs);
294 		return res;
295 	}
296 
297 	res = i2c_transfer(client->adapter, msgs, nmsgs);
298 	while (i-- > 0) {
299 		if (res >= 0 && (msgs[i].flags & I2C_M_RD)) {
300 			if (copy_to_user(data_ptrs[i], msgs[i].buf,
301 					 msgs[i].len))
302 				res = -EFAULT;
303 		}
304 		kfree(msgs[i].buf);
305 	}
306 	kfree(data_ptrs);
307 	kfree(msgs);
308 	return res;
309 }
310 
311 static noinline int i2cdev_ioctl_smbus(struct i2c_client *client,
312 		u8 read_write, u8 command, u32 size,
313 		union i2c_smbus_data __user *data)
314 {
315 	union i2c_smbus_data temp = {};
316 	int datasize, res;
317 
318 	if ((size != I2C_SMBUS_BYTE) &&
319 	    (size != I2C_SMBUS_QUICK) &&
320 	    (size != I2C_SMBUS_BYTE_DATA) &&
321 	    (size != I2C_SMBUS_WORD_DATA) &&
322 	    (size != I2C_SMBUS_PROC_CALL) &&
323 	    (size != I2C_SMBUS_BLOCK_DATA) &&
324 	    (size != I2C_SMBUS_I2C_BLOCK_BROKEN) &&
325 	    (size != I2C_SMBUS_I2C_BLOCK_DATA) &&
326 	    (size != I2C_SMBUS_BLOCK_PROC_CALL)) {
327 		dev_dbg(&client->adapter->dev,
328 			"size out of range (%x) in ioctl I2C_SMBUS.\n",
329 			size);
330 		return -EINVAL;
331 	}
332 	/* Note that I2C_SMBUS_READ and I2C_SMBUS_WRITE are 0 and 1,
333 	   so the check is valid if size==I2C_SMBUS_QUICK too. */
334 	if ((read_write != I2C_SMBUS_READ) &&
335 	    (read_write != I2C_SMBUS_WRITE)) {
336 		dev_dbg(&client->adapter->dev,
337 			"read_write out of range (%x) in ioctl I2C_SMBUS.\n",
338 			read_write);
339 		return -EINVAL;
340 	}
341 
342 	/* Note that command values are always valid! */
343 
344 	if ((size == I2C_SMBUS_QUICK) ||
345 	    ((size == I2C_SMBUS_BYTE) &&
346 	    (read_write == I2C_SMBUS_WRITE)))
347 		/* These are special: we do not use data */
348 		return i2c_smbus_xfer(client->adapter, client->addr,
349 				      client->flags, read_write,
350 				      command, size, NULL);
351 
352 	if (data == NULL) {
353 		dev_dbg(&client->adapter->dev,
354 			"data is NULL pointer in ioctl I2C_SMBUS.\n");
355 		return -EINVAL;
356 	}
357 
358 	if ((size == I2C_SMBUS_BYTE_DATA) ||
359 	    (size == I2C_SMBUS_BYTE))
360 		datasize = sizeof(data->byte);
361 	else if ((size == I2C_SMBUS_WORD_DATA) ||
362 		 (size == I2C_SMBUS_PROC_CALL))
363 		datasize = sizeof(data->word);
364 	else /* size == smbus block, i2c block, or block proc. call */
365 		datasize = sizeof(data->block);
366 
367 	if ((size == I2C_SMBUS_PROC_CALL) ||
368 	    (size == I2C_SMBUS_BLOCK_PROC_CALL) ||
369 	    (size == I2C_SMBUS_I2C_BLOCK_DATA) ||
370 	    (read_write == I2C_SMBUS_WRITE)) {
371 		if (copy_from_user(&temp, data, datasize))
372 			return -EFAULT;
373 	}
374 	if (size == I2C_SMBUS_I2C_BLOCK_BROKEN) {
375 		/* Convert old I2C block commands to the new
376 		   convention. This preserves binary compatibility. */
377 		size = I2C_SMBUS_I2C_BLOCK_DATA;
378 		if (read_write == I2C_SMBUS_READ)
379 			temp.block[0] = I2C_SMBUS_BLOCK_MAX;
380 	}
381 	res = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
382 	      read_write, command, size, &temp);
383 	if (!res && ((size == I2C_SMBUS_PROC_CALL) ||
384 		     (size == I2C_SMBUS_BLOCK_PROC_CALL) ||
385 		     (read_write == I2C_SMBUS_READ))) {
386 		if (copy_to_user(data, &temp, datasize))
387 			return -EFAULT;
388 	}
389 	return res;
390 }
391 
392 static long i2cdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
393 {
394 	struct i2c_client *client = file->private_data;
395 	unsigned long funcs;
396 
397 	dev_dbg(&client->adapter->dev, "ioctl, cmd=0x%02x, arg=0x%02lx\n",
398 		cmd, arg);
399 
400 	switch (cmd) {
401 	case I2C_SLAVE:
402 	case I2C_SLAVE_FORCE:
403 		if ((arg > 0x3ff) ||
404 		    (((client->flags & I2C_M_TEN) == 0) && arg > 0x7f))
405 			return -EINVAL;
406 		if (cmd == I2C_SLAVE && i2cdev_check_addr(client->adapter, arg))
407 			return -EBUSY;
408 		/* REVISIT: address could become busy later */
409 		client->addr = arg;
410 		return 0;
411 	case I2C_TENBIT:
412 		if (arg)
413 			client->flags |= I2C_M_TEN;
414 		else
415 			client->flags &= ~I2C_M_TEN;
416 		return 0;
417 	case I2C_PEC:
418 		/*
419 		 * Setting the PEC flag here won't affect kernel drivers,
420 		 * which will be using the i2c_client node registered with
421 		 * the driver model core.  Likewise, when that client has
422 		 * the PEC flag already set, the i2c-dev driver won't see
423 		 * (or use) this setting.
424 		 */
425 		if (arg)
426 			client->flags |= I2C_CLIENT_PEC;
427 		else
428 			client->flags &= ~I2C_CLIENT_PEC;
429 		return 0;
430 	case I2C_FUNCS:
431 		funcs = i2c_get_functionality(client->adapter);
432 		return put_user(funcs, (unsigned long __user *)arg);
433 
434 	case I2C_RDWR: {
435 		struct i2c_rdwr_ioctl_data rdwr_arg;
436 		struct i2c_msg *rdwr_pa;
437 
438 		if (copy_from_user(&rdwr_arg,
439 				   (struct i2c_rdwr_ioctl_data __user *)arg,
440 				   sizeof(rdwr_arg)))
441 			return -EFAULT;
442 
443 		if (!rdwr_arg.msgs || rdwr_arg.nmsgs == 0)
444 			return -EINVAL;
445 
446 		/*
447 		 * Put an arbitrary limit on the number of messages that can
448 		 * be sent at once
449 		 */
450 		if (rdwr_arg.nmsgs > I2C_RDWR_IOCTL_MAX_MSGS)
451 			return -EINVAL;
452 
453 		rdwr_pa = memdup_user(rdwr_arg.msgs,
454 				      rdwr_arg.nmsgs * sizeof(struct i2c_msg));
455 		if (IS_ERR(rdwr_pa))
456 			return PTR_ERR(rdwr_pa);
457 
458 		return i2cdev_ioctl_rdwr(client, rdwr_arg.nmsgs, rdwr_pa);
459 	}
460 
461 	case I2C_SMBUS: {
462 		struct i2c_smbus_ioctl_data data_arg;
463 		if (copy_from_user(&data_arg,
464 				   (struct i2c_smbus_ioctl_data __user *) arg,
465 				   sizeof(struct i2c_smbus_ioctl_data)))
466 			return -EFAULT;
467 		return i2cdev_ioctl_smbus(client, data_arg.read_write,
468 					  data_arg.command,
469 					  data_arg.size,
470 					  data_arg.data);
471 	}
472 	case I2C_RETRIES:
473 		if (arg > INT_MAX)
474 			return -EINVAL;
475 
476 		client->adapter->retries = arg;
477 		break;
478 	case I2C_TIMEOUT:
479 		if (arg > INT_MAX)
480 			return -EINVAL;
481 
482 		/* For historical reasons, user-space sets the timeout
483 		 * value in units of 10 ms.
484 		 */
485 		client->adapter->timeout = msecs_to_jiffies(arg * 10);
486 		break;
487 	default:
488 		/* NOTE:  returning a fault code here could cause trouble
489 		 * in buggy userspace code.  Some old kernel bugs returned
490 		 * zero in this case, and userspace code might accidentally
491 		 * have depended on that bug.
492 		 */
493 		return -ENOTTY;
494 	}
495 	return 0;
496 }
497 
498 #ifdef CONFIG_COMPAT
499 
500 struct i2c_smbus_ioctl_data32 {
501 	u8 read_write;
502 	u8 command;
503 	u32 size;
504 	compat_caddr_t data; /* union i2c_smbus_data *data */
505 };
506 
507 struct i2c_msg32 {
508 	u16 addr;
509 	u16 flags;
510 	u16 len;
511 	compat_caddr_t buf;
512 };
513 
514 struct i2c_rdwr_ioctl_data32 {
515 	compat_caddr_t msgs; /* struct i2c_msg __user *msgs */
516 	u32 nmsgs;
517 };
518 
519 static long compat_i2cdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
520 {
521 	struct i2c_client *client = file->private_data;
522 	unsigned long funcs;
523 	switch (cmd) {
524 	case I2C_FUNCS:
525 		funcs = i2c_get_functionality(client->adapter);
526 		return put_user(funcs, (compat_ulong_t __user *)arg);
527 	case I2C_RDWR: {
528 		struct i2c_rdwr_ioctl_data32 rdwr_arg;
529 		struct i2c_msg32 *p;
530 		struct i2c_msg *rdwr_pa;
531 		int i;
532 
533 		if (copy_from_user(&rdwr_arg,
534 				   (struct i2c_rdwr_ioctl_data32 __user *)arg,
535 				   sizeof(rdwr_arg)))
536 			return -EFAULT;
537 
538 		if (rdwr_arg.nmsgs > I2C_RDWR_IOCTL_MAX_MSGS)
539 			return -EINVAL;
540 
541 		rdwr_pa = kmalloc_array(rdwr_arg.nmsgs, sizeof(struct i2c_msg),
542 				      GFP_KERNEL);
543 		if (!rdwr_pa)
544 			return -ENOMEM;
545 
546 		p = compat_ptr(rdwr_arg.msgs);
547 		for (i = 0; i < rdwr_arg.nmsgs; i++) {
548 			struct i2c_msg32 umsg;
549 			if (copy_from_user(&umsg, p + i, sizeof(umsg))) {
550 				kfree(rdwr_pa);
551 				return -EFAULT;
552 			}
553 			rdwr_pa[i] = (struct i2c_msg) {
554 				.addr = umsg.addr,
555 				.flags = umsg.flags,
556 				.len = umsg.len,
557 				.buf = compat_ptr(umsg.buf)
558 			};
559 		}
560 
561 		return i2cdev_ioctl_rdwr(client, rdwr_arg.nmsgs, rdwr_pa);
562 	}
563 	case I2C_SMBUS: {
564 		struct i2c_smbus_ioctl_data32	data32;
565 		if (copy_from_user(&data32,
566 				   (void __user *) arg,
567 				   sizeof(data32)))
568 			return -EFAULT;
569 		return i2cdev_ioctl_smbus(client, data32.read_write,
570 					  data32.command,
571 					  data32.size,
572 					  compat_ptr(data32.data));
573 	}
574 	default:
575 		return i2cdev_ioctl(file, cmd, arg);
576 	}
577 }
578 #else
579 #define compat_i2cdev_ioctl NULL
580 #endif
581 
582 static int i2cdev_open(struct inode *inode, struct file *file)
583 {
584 	unsigned int minor = iminor(inode);
585 	struct i2c_client *client;
586 	struct i2c_adapter *adap;
587 
588 	adap = i2c_get_adapter(minor);
589 	if (!adap)
590 		return -ENODEV;
591 
592 	/* This creates an anonymous i2c_client, which may later be
593 	 * pointed to some address using I2C_SLAVE or I2C_SLAVE_FORCE.
594 	 *
595 	 * This client is ** NEVER REGISTERED ** with the driver model
596 	 * or I2C core code!!  It just holds private copies of addressing
597 	 * information and maybe a PEC flag.
598 	 */
599 	client = kzalloc(sizeof(*client), GFP_KERNEL);
600 	if (!client) {
601 		i2c_put_adapter(adap);
602 		return -ENOMEM;
603 	}
604 	snprintf(client->name, I2C_NAME_SIZE, "i2c-dev %d", adap->nr);
605 
606 	client->adapter = adap;
607 	file->private_data = client;
608 
609 	return 0;
610 }
611 
612 static int i2cdev_release(struct inode *inode, struct file *file)
613 {
614 	struct i2c_client *client = file->private_data;
615 
616 	i2c_put_adapter(client->adapter);
617 	kfree(client);
618 	file->private_data = NULL;
619 
620 	return 0;
621 }
622 
623 static const struct file_operations i2cdev_fops = {
624 	.owner		= THIS_MODULE,
625 	.llseek		= no_llseek,
626 	.read		= i2cdev_read,
627 	.write		= i2cdev_write,
628 	.unlocked_ioctl	= i2cdev_ioctl,
629 	.compat_ioctl	= compat_i2cdev_ioctl,
630 	.open		= i2cdev_open,
631 	.release	= i2cdev_release,
632 };
633 
634 /* ------------------------------------------------------------------------- */
635 
636 static struct class *i2c_dev_class;
637 
638 static void i2cdev_dev_release(struct device *dev)
639 {
640 	struct i2c_dev *i2c_dev;
641 
642 	i2c_dev = container_of(dev, struct i2c_dev, dev);
643 	kfree(i2c_dev);
644 }
645 
646 static int i2cdev_attach_adapter(struct device *dev, void *dummy)
647 {
648 	struct i2c_adapter *adap;
649 	struct i2c_dev *i2c_dev;
650 	int res;
651 
652 	if (dev->type != &i2c_adapter_type)
653 		return 0;
654 	adap = to_i2c_adapter(dev);
655 
656 	i2c_dev = get_free_i2c_dev(adap);
657 	if (IS_ERR(i2c_dev))
658 		return PTR_ERR(i2c_dev);
659 
660 	cdev_init(&i2c_dev->cdev, &i2cdev_fops);
661 	i2c_dev->cdev.owner = THIS_MODULE;
662 
663 	device_initialize(&i2c_dev->dev);
664 	i2c_dev->dev.devt = MKDEV(I2C_MAJOR, adap->nr);
665 	i2c_dev->dev.class = i2c_dev_class;
666 	i2c_dev->dev.parent = &adap->dev;
667 	i2c_dev->dev.release = i2cdev_dev_release;
668 	dev_set_name(&i2c_dev->dev, "i2c-%d", adap->nr);
669 
670 	res = cdev_device_add(&i2c_dev->cdev, &i2c_dev->dev);
671 	if (res) {
672 		put_i2c_dev(i2c_dev, false);
673 		return res;
674 	}
675 
676 	pr_debug("i2c-dev: adapter [%s] registered as minor %d\n",
677 		 adap->name, adap->nr);
678 	return 0;
679 }
680 
681 static int i2cdev_detach_adapter(struct device *dev, void *dummy)
682 {
683 	struct i2c_adapter *adap;
684 	struct i2c_dev *i2c_dev;
685 
686 	if (dev->type != &i2c_adapter_type)
687 		return 0;
688 	adap = to_i2c_adapter(dev);
689 
690 	i2c_dev = i2c_dev_get_by_minor(adap->nr);
691 	if (!i2c_dev) /* attach_adapter must have failed */
692 		return 0;
693 
694 	put_i2c_dev(i2c_dev, true);
695 
696 	pr_debug("i2c-dev: adapter [%s] unregistered\n", adap->name);
697 	return 0;
698 }
699 
700 static int i2cdev_notifier_call(struct notifier_block *nb, unsigned long action,
701 			 void *data)
702 {
703 	struct device *dev = data;
704 
705 	switch (action) {
706 	case BUS_NOTIFY_ADD_DEVICE:
707 		return i2cdev_attach_adapter(dev, NULL);
708 	case BUS_NOTIFY_DEL_DEVICE:
709 		return i2cdev_detach_adapter(dev, NULL);
710 	}
711 
712 	return 0;
713 }
714 
715 static struct notifier_block i2cdev_notifier = {
716 	.notifier_call = i2cdev_notifier_call,
717 };
718 
719 /* ------------------------------------------------------------------------- */
720 
721 /*
722  * module load/unload record keeping
723  */
724 
725 static int __init i2c_dev_init(void)
726 {
727 	int res;
728 
729 	printk(KERN_INFO "i2c /dev entries driver\n");
730 
731 	res = register_chrdev_region(MKDEV(I2C_MAJOR, 0), I2C_MINORS, "i2c");
732 	if (res)
733 		goto out;
734 
735 	i2c_dev_class = class_create(THIS_MODULE, "i2c-dev");
736 	if (IS_ERR(i2c_dev_class)) {
737 		res = PTR_ERR(i2c_dev_class);
738 		goto out_unreg_chrdev;
739 	}
740 	i2c_dev_class->dev_groups = i2c_groups;
741 
742 	/* Keep track of adapters which will be added or removed later */
743 	res = bus_register_notifier(&i2c_bus_type, &i2cdev_notifier);
744 	if (res)
745 		goto out_unreg_class;
746 
747 	/* Bind to already existing adapters right away */
748 	i2c_for_each_dev(NULL, i2cdev_attach_adapter);
749 
750 	return 0;
751 
752 out_unreg_class:
753 	class_destroy(i2c_dev_class);
754 out_unreg_chrdev:
755 	unregister_chrdev_region(MKDEV(I2C_MAJOR, 0), I2C_MINORS);
756 out:
757 	printk(KERN_ERR "%s: Driver Initialisation failed\n", __FILE__);
758 	return res;
759 }
760 
761 static void __exit i2c_dev_exit(void)
762 {
763 	bus_unregister_notifier(&i2c_bus_type, &i2cdev_notifier);
764 	i2c_for_each_dev(NULL, i2cdev_detach_adapter);
765 	class_destroy(i2c_dev_class);
766 	unregister_chrdev_region(MKDEV(I2C_MAJOR, 0), I2C_MINORS);
767 }
768 
769 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl>");
770 MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>");
771 MODULE_DESCRIPTION("I2C /dev entries driver");
772 MODULE_LICENSE("GPL");
773 
774 module_init(i2c_dev_init);
775 module_exit(i2c_dev_exit);
776