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 #define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt
18 
19 #include <linux/cdev.h>
20 #include <linux/compat.h>
21 #include <linux/device.h>
22 #include <linux/fs.h>
23 #include <linux/i2c-dev.h>
24 #include <linux/i2c.h>
25 #include <linux/init.h>
26 #include <linux/jiffies.h>
27 #include <linux/kernel.h>
28 #include <linux/list.h>
29 #include <linux/module.h>
30 #include <linux/notifier.h>
31 #include <linux/slab.h>
32 #include <linux/uaccess.h>
33 
34 /*
35  * An i2c_dev represents an i2c_adapter ... an I2C or SMBus master, not a
36  * slave (i2c_client) with which messages will be exchanged.  It's coupled
37  * with a character special file which is accessed by user mode drivers.
38  *
39  * The list of i2c_dev structures is parallel to the i2c_adapter lists
40  * maintained by the driver model, and is updated using bus notifications.
41  */
42 struct i2c_dev {
43 	struct list_head list;
44 	struct i2c_adapter *adap;
45 	struct device dev;
46 	struct cdev cdev;
47 };
48 
49 #define I2C_MINORS	(MINORMASK + 1)
50 static LIST_HEAD(i2c_dev_list);
51 static DEFINE_SPINLOCK(i2c_dev_list_lock);
52 
i2c_dev_get_by_minor(unsigned index)53 static struct i2c_dev *i2c_dev_get_by_minor(unsigned index)
54 {
55 	struct i2c_dev *i2c_dev;
56 
57 	spin_lock(&i2c_dev_list_lock);
58 	list_for_each_entry(i2c_dev, &i2c_dev_list, list) {
59 		if (i2c_dev->adap->nr == index)
60 			goto found;
61 	}
62 	i2c_dev = NULL;
63 found:
64 	spin_unlock(&i2c_dev_list_lock);
65 	return i2c_dev;
66 }
67 
get_free_i2c_dev(struct i2c_adapter * adap)68 static struct i2c_dev *get_free_i2c_dev(struct i2c_adapter *adap)
69 {
70 	struct i2c_dev *i2c_dev;
71 
72 	if (adap->nr >= I2C_MINORS) {
73 		pr_err("Out of device minors (%d)\n", adap->nr);
74 		return ERR_PTR(-ENODEV);
75 	}
76 
77 	i2c_dev = kzalloc(sizeof(*i2c_dev), GFP_KERNEL);
78 	if (!i2c_dev)
79 		return ERR_PTR(-ENOMEM);
80 	i2c_dev->adap = adap;
81 
82 	spin_lock(&i2c_dev_list_lock);
83 	list_add_tail(&i2c_dev->list, &i2c_dev_list);
84 	spin_unlock(&i2c_dev_list_lock);
85 	return i2c_dev;
86 }
87 
put_i2c_dev(struct i2c_dev * i2c_dev,bool del_cdev)88 static void put_i2c_dev(struct i2c_dev *i2c_dev, bool del_cdev)
89 {
90 	spin_lock(&i2c_dev_list_lock);
91 	list_del(&i2c_dev->list);
92 	spin_unlock(&i2c_dev_list_lock);
93 	if (del_cdev)
94 		cdev_device_del(&i2c_dev->cdev, &i2c_dev->dev);
95 	put_device(&i2c_dev->dev);
96 }
97 
name_show(struct device * dev,struct device_attribute * attr,char * buf)98 static ssize_t name_show(struct device *dev,
99 			 struct device_attribute *attr, char *buf)
100 {
101 	struct i2c_dev *i2c_dev = i2c_dev_get_by_minor(MINOR(dev->devt));
102 
103 	if (!i2c_dev)
104 		return -ENODEV;
105 	return sysfs_emit(buf, "%s\n", i2c_dev->adap->name);
106 }
107 static DEVICE_ATTR_RO(name);
108 
109 static struct attribute *i2c_attrs[] = {
110 	&dev_attr_name.attr,
111 	NULL,
112 };
113 ATTRIBUTE_GROUPS(i2c);
114 
115 /* ------------------------------------------------------------------------- */
116 
117 /*
118  * After opening an instance of this character special file, a file
119  * descriptor starts out associated only with an i2c_adapter (and bus).
120  *
121  * Using the I2C_RDWR ioctl(), you can then *immediately* issue i2c_msg
122  * traffic to any devices on the bus used by that adapter.  That's because
123  * the i2c_msg vectors embed all the addressing information they need, and
124  * are submitted directly to an i2c_adapter.  However, SMBus-only adapters
125  * don't support that interface.
126  *
127  * To use read()/write() system calls on that file descriptor, or to use
128  * SMBus interfaces (and work with SMBus-only hosts!), you must first issue
129  * an I2C_SLAVE (or I2C_SLAVE_FORCE) ioctl.  That configures an anonymous
130  * (never registered) i2c_client so it holds the addressing information
131  * needed by those system calls and by this SMBus interface.
132  */
133 
i2cdev_read(struct file * file,char __user * buf,size_t count,loff_t * offset)134 static ssize_t i2cdev_read(struct file *file, char __user *buf, size_t count,
135 		loff_t *offset)
136 {
137 	char *tmp;
138 	int ret;
139 
140 	struct i2c_client *client = file->private_data;
141 
142 	if (count > 8192)
143 		count = 8192;
144 
145 	tmp = kzalloc(count, GFP_KERNEL);
146 	if (tmp == NULL)
147 		return -ENOMEM;
148 
149 	pr_debug("i2c-%d reading %zu bytes.\n", iminor(file_inode(file)), count);
150 
151 	ret = i2c_master_recv(client, tmp, count);
152 	if (ret >= 0)
153 		if (copy_to_user(buf, tmp, ret))
154 			ret = -EFAULT;
155 	kfree(tmp);
156 	return ret;
157 }
158 
i2cdev_write(struct file * file,const char __user * buf,size_t count,loff_t * offset)159 static ssize_t i2cdev_write(struct file *file, const char __user *buf,
160 		size_t count, loff_t *offset)
161 {
162 	int ret;
163 	char *tmp;
164 	struct i2c_client *client = file->private_data;
165 
166 	if (count > 8192)
167 		count = 8192;
168 
169 	tmp = memdup_user(buf, count);
170 	if (IS_ERR(tmp))
171 		return PTR_ERR(tmp);
172 
173 	pr_debug("i2c-%d writing %zu bytes.\n", iminor(file_inode(file)), count);
174 
175 	ret = i2c_master_send(client, tmp, count);
176 	kfree(tmp);
177 	return ret;
178 }
179 
i2cdev_check(struct device * dev,void * addrp)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 */
i2cdev_check_mux_parents(struct i2c_adapter * adapter,int addr)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 */
i2cdev_check_mux_children(struct device * dev,void * addrp)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. */
i2cdev_check_addr(struct i2c_adapter * adapter,unsigned int addr)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 
i2cdev_ioctl_rdwr(struct i2c_client * client,unsigned nmsgs,struct i2c_msg * msgs)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 
i2cdev_ioctl_smbus(struct i2c_client * client,u8 read_write,u8 command,u32 size,union i2c_smbus_data __user * data)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 
i2cdev_ioctl(struct file * file,unsigned int cmd,unsigned long arg)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 
compat_i2cdev_ioctl(struct file * file,unsigned int cmd,unsigned long arg)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 __user *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.msgs || rdwr_arg.nmsgs == 0)
539 			return -EINVAL;
540 
541 		if (rdwr_arg.nmsgs > I2C_RDWR_IOCTL_MAX_MSGS)
542 			return -EINVAL;
543 
544 		rdwr_pa = kmalloc_array(rdwr_arg.nmsgs, sizeof(struct i2c_msg),
545 				      GFP_KERNEL);
546 		if (!rdwr_pa)
547 			return -ENOMEM;
548 
549 		p = compat_ptr(rdwr_arg.msgs);
550 		for (i = 0; i < rdwr_arg.nmsgs; i++) {
551 			struct i2c_msg32 umsg;
552 			if (copy_from_user(&umsg, p + i, sizeof(umsg))) {
553 				kfree(rdwr_pa);
554 				return -EFAULT;
555 			}
556 			rdwr_pa[i] = (struct i2c_msg) {
557 				.addr = umsg.addr,
558 				.flags = umsg.flags,
559 				.len = umsg.len,
560 				.buf = (__force __u8 *)compat_ptr(umsg.buf),
561 			};
562 		}
563 
564 		return i2cdev_ioctl_rdwr(client, rdwr_arg.nmsgs, rdwr_pa);
565 	}
566 	case I2C_SMBUS: {
567 		struct i2c_smbus_ioctl_data32	data32;
568 		if (copy_from_user(&data32,
569 				   (void __user *) arg,
570 				   sizeof(data32)))
571 			return -EFAULT;
572 		return i2cdev_ioctl_smbus(client, data32.read_write,
573 					  data32.command,
574 					  data32.size,
575 					  compat_ptr(data32.data));
576 	}
577 	default:
578 		return i2cdev_ioctl(file, cmd, arg);
579 	}
580 }
581 #else
582 #define compat_i2cdev_ioctl NULL
583 #endif
584 
i2cdev_open(struct inode * inode,struct file * file)585 static int i2cdev_open(struct inode *inode, struct file *file)
586 {
587 	unsigned int minor = iminor(inode);
588 	struct i2c_client *client;
589 	struct i2c_adapter *adap;
590 
591 	adap = i2c_get_adapter(minor);
592 	if (!adap)
593 		return -ENODEV;
594 
595 	/* This creates an anonymous i2c_client, which may later be
596 	 * pointed to some address using I2C_SLAVE or I2C_SLAVE_FORCE.
597 	 *
598 	 * This client is ** NEVER REGISTERED ** with the driver model
599 	 * or I2C core code!!  It just holds private copies of addressing
600 	 * information and maybe a PEC flag.
601 	 */
602 	client = kzalloc(sizeof(*client), GFP_KERNEL);
603 	if (!client) {
604 		i2c_put_adapter(adap);
605 		return -ENOMEM;
606 	}
607 	snprintf(client->name, I2C_NAME_SIZE, "i2c-dev %d", adap->nr);
608 
609 	client->adapter = adap;
610 	file->private_data = client;
611 
612 	return 0;
613 }
614 
i2cdev_release(struct inode * inode,struct file * file)615 static int i2cdev_release(struct inode *inode, struct file *file)
616 {
617 	struct i2c_client *client = file->private_data;
618 
619 	i2c_put_adapter(client->adapter);
620 	kfree(client);
621 	file->private_data = NULL;
622 
623 	return 0;
624 }
625 
626 static const struct file_operations i2cdev_fops = {
627 	.owner		= THIS_MODULE,
628 	.llseek		= no_llseek,
629 	.read		= i2cdev_read,
630 	.write		= i2cdev_write,
631 	.unlocked_ioctl	= i2cdev_ioctl,
632 	.compat_ioctl	= compat_i2cdev_ioctl,
633 	.open		= i2cdev_open,
634 	.release	= i2cdev_release,
635 };
636 
637 /* ------------------------------------------------------------------------- */
638 
639 static struct class *i2c_dev_class;
640 
i2cdev_dev_release(struct device * dev)641 static void i2cdev_dev_release(struct device *dev)
642 {
643 	struct i2c_dev *i2c_dev;
644 
645 	i2c_dev = container_of(dev, struct i2c_dev, dev);
646 	kfree(i2c_dev);
647 }
648 
i2cdev_attach_adapter(struct device * dev,void * dummy)649 static int i2cdev_attach_adapter(struct device *dev, void *dummy)
650 {
651 	struct i2c_adapter *adap;
652 	struct i2c_dev *i2c_dev;
653 	int res;
654 
655 	if (dev->type != &i2c_adapter_type)
656 		return 0;
657 	adap = to_i2c_adapter(dev);
658 
659 	i2c_dev = get_free_i2c_dev(adap);
660 	if (IS_ERR(i2c_dev))
661 		return PTR_ERR(i2c_dev);
662 
663 	cdev_init(&i2c_dev->cdev, &i2cdev_fops);
664 	i2c_dev->cdev.owner = THIS_MODULE;
665 
666 	device_initialize(&i2c_dev->dev);
667 	i2c_dev->dev.devt = MKDEV(I2C_MAJOR, adap->nr);
668 	i2c_dev->dev.class = i2c_dev_class;
669 	i2c_dev->dev.parent = &adap->dev;
670 	i2c_dev->dev.release = i2cdev_dev_release;
671 
672 	res = dev_set_name(&i2c_dev->dev, "i2c-%d", adap->nr);
673 	if (res)
674 		goto err_put_i2c_dev;
675 
676 	res = cdev_device_add(&i2c_dev->cdev, &i2c_dev->dev);
677 	if (res)
678 		goto err_put_i2c_dev;
679 
680 	pr_debug("adapter [%s] registered as minor %d\n", adap->name, adap->nr);
681 	return 0;
682 
683 err_put_i2c_dev:
684 	put_i2c_dev(i2c_dev, false);
685 	return res;
686 }
687 
i2cdev_detach_adapter(struct device * dev,void * dummy)688 static int i2cdev_detach_adapter(struct device *dev, void *dummy)
689 {
690 	struct i2c_adapter *adap;
691 	struct i2c_dev *i2c_dev;
692 
693 	if (dev->type != &i2c_adapter_type)
694 		return 0;
695 	adap = to_i2c_adapter(dev);
696 
697 	i2c_dev = i2c_dev_get_by_minor(adap->nr);
698 	if (!i2c_dev) /* attach_adapter must have failed */
699 		return 0;
700 
701 	put_i2c_dev(i2c_dev, true);
702 
703 	pr_debug("adapter [%s] unregistered\n", adap->name);
704 	return 0;
705 }
706 
i2cdev_notifier_call(struct notifier_block * nb,unsigned long action,void * data)707 static int i2cdev_notifier_call(struct notifier_block *nb, unsigned long action,
708 			 void *data)
709 {
710 	struct device *dev = data;
711 
712 	switch (action) {
713 	case BUS_NOTIFY_ADD_DEVICE:
714 		return i2cdev_attach_adapter(dev, NULL);
715 	case BUS_NOTIFY_DEL_DEVICE:
716 		return i2cdev_detach_adapter(dev, NULL);
717 	}
718 
719 	return 0;
720 }
721 
722 static struct notifier_block i2cdev_notifier = {
723 	.notifier_call = i2cdev_notifier_call,
724 };
725 
726 /* ------------------------------------------------------------------------- */
727 
728 /*
729  * module load/unload record keeping
730  */
731 
i2c_dev_init(void)732 static int __init i2c_dev_init(void)
733 {
734 	int res;
735 
736 	pr_info("i2c /dev entries driver\n");
737 
738 	res = register_chrdev_region(MKDEV(I2C_MAJOR, 0), I2C_MINORS, "i2c");
739 	if (res)
740 		goto out;
741 
742 	i2c_dev_class = class_create(THIS_MODULE, "i2c-dev");
743 	if (IS_ERR(i2c_dev_class)) {
744 		res = PTR_ERR(i2c_dev_class);
745 		goto out_unreg_chrdev;
746 	}
747 	i2c_dev_class->dev_groups = i2c_groups;
748 
749 	/* Keep track of adapters which will be added or removed later */
750 	res = bus_register_notifier(&i2c_bus_type, &i2cdev_notifier);
751 	if (res)
752 		goto out_unreg_class;
753 
754 	/* Bind to already existing adapters right away */
755 	i2c_for_each_dev(NULL, i2cdev_attach_adapter);
756 
757 	return 0;
758 
759 out_unreg_class:
760 	class_destroy(i2c_dev_class);
761 out_unreg_chrdev:
762 	unregister_chrdev_region(MKDEV(I2C_MAJOR, 0), I2C_MINORS);
763 out:
764 	pr_err("Driver Initialisation failed\n");
765 	return res;
766 }
767 
i2c_dev_exit(void)768 static void __exit i2c_dev_exit(void)
769 {
770 	bus_unregister_notifier(&i2c_bus_type, &i2cdev_notifier);
771 	i2c_for_each_dev(NULL, i2cdev_detach_adapter);
772 	class_destroy(i2c_dev_class);
773 	unregister_chrdev_region(MKDEV(I2C_MAJOR, 0), I2C_MINORS);
774 }
775 
776 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl>");
777 MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>");
778 MODULE_DESCRIPTION("I2C /dev entries driver");
779 MODULE_LICENSE("GPL");
780 
781 module_init(i2c_dev_init);
782 module_exit(i2c_dev_exit);
783