xref: /linux/drivers/i2c/i2c-dev.c (revision 3fd6c59042dbba50391e30862beac979491145fe)
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 	/* Adapter must support I2C transfers */
143 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
144 		return -EOPNOTSUPP;
145 
146 	if (count > 8192)
147 		count = 8192;
148 
149 	tmp = kzalloc(count, GFP_KERNEL);
150 	if (tmp == NULL)
151 		return -ENOMEM;
152 
153 	pr_debug("i2c-%d reading %zu bytes.\n", iminor(file_inode(file)), count);
154 
155 	ret = i2c_master_recv(client, tmp, count);
156 	if (ret >= 0)
157 		if (copy_to_user(buf, tmp, ret))
158 			ret = -EFAULT;
159 	kfree(tmp);
160 	return ret;
161 }
162 
i2cdev_write(struct file * file,const char __user * buf,size_t count,loff_t * offset)163 static ssize_t i2cdev_write(struct file *file, const char __user *buf,
164 		size_t count, loff_t *offset)
165 {
166 	int ret;
167 	char *tmp;
168 	struct i2c_client *client = file->private_data;
169 
170 	/* Adapter must support I2C transfers */
171 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
172 		return -EOPNOTSUPP;
173 
174 	if (count > 8192)
175 		count = 8192;
176 
177 	tmp = memdup_user(buf, count);
178 	if (IS_ERR(tmp))
179 		return PTR_ERR(tmp);
180 
181 	pr_debug("i2c-%d writing %zu bytes.\n", iminor(file_inode(file)), count);
182 
183 	ret = i2c_master_send(client, tmp, count);
184 	kfree(tmp);
185 	return ret;
186 }
187 
i2cdev_check(struct device * dev,void * addrp)188 static int i2cdev_check(struct device *dev, void *addrp)
189 {
190 	struct i2c_client *client = i2c_verify_client(dev);
191 
192 	if (!client || client->addr != *(unsigned int *)addrp)
193 		return 0;
194 
195 	return dev->driver ? -EBUSY : 0;
196 }
197 
198 /* walk up mux tree */
i2cdev_check_mux_parents(struct i2c_adapter * adapter,int addr)199 static int i2cdev_check_mux_parents(struct i2c_adapter *adapter, int addr)
200 {
201 	struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
202 	int result;
203 
204 	result = device_for_each_child(&adapter->dev, &addr, i2cdev_check);
205 	if (!result && parent)
206 		result = i2cdev_check_mux_parents(parent, addr);
207 
208 	return result;
209 }
210 
211 /* recurse down mux tree */
i2cdev_check_mux_children(struct device * dev,void * addrp)212 static int i2cdev_check_mux_children(struct device *dev, void *addrp)
213 {
214 	int result;
215 
216 	if (dev->type == &i2c_adapter_type)
217 		result = device_for_each_child(dev, addrp,
218 						i2cdev_check_mux_children);
219 	else
220 		result = i2cdev_check(dev, addrp);
221 
222 	return result;
223 }
224 
225 /* This address checking function differs from the one in i2c-core
226    in that it considers an address with a registered device, but no
227    driver bound to it, as NOT busy. */
i2cdev_check_addr(struct i2c_adapter * adapter,unsigned int addr)228 static int i2cdev_check_addr(struct i2c_adapter *adapter, unsigned int addr)
229 {
230 	struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
231 	int result = 0;
232 
233 	if (parent)
234 		result = i2cdev_check_mux_parents(parent, addr);
235 
236 	if (!result)
237 		result = device_for_each_child(&adapter->dev, &addr,
238 						i2cdev_check_mux_children);
239 
240 	return result;
241 }
242 
i2cdev_ioctl_rdwr(struct i2c_client * client,unsigned nmsgs,struct i2c_msg * msgs)243 static noinline int i2cdev_ioctl_rdwr(struct i2c_client *client,
244 		unsigned nmsgs, struct i2c_msg *msgs)
245 {
246 	u8 __user **data_ptrs;
247 	int i, res;
248 
249 	/* Adapter must support I2C transfers */
250 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
251 		return -EOPNOTSUPP;
252 
253 	data_ptrs = kmalloc_array(nmsgs, sizeof(u8 __user *), GFP_KERNEL);
254 	if (!data_ptrs)
255 		return -ENOMEM;
256 
257 	res = 0;
258 	for (i = 0; i < nmsgs; i++) {
259 		/* Limit the size of the message to a sane amount */
260 		if (msgs[i].len > 8192) {
261 			res = -EINVAL;
262 			break;
263 		}
264 
265 		data_ptrs[i] = (u8 __user *)msgs[i].buf;
266 		msgs[i].buf = memdup_user(data_ptrs[i], msgs[i].len);
267 		if (IS_ERR(msgs[i].buf)) {
268 			res = PTR_ERR(msgs[i].buf);
269 			break;
270 		}
271 		/* memdup_user allocates with GFP_KERNEL, so DMA is ok */
272 		msgs[i].flags |= I2C_M_DMA_SAFE;
273 
274 		/*
275 		 * If the message length is received from the slave (similar
276 		 * to SMBus block read), we must ensure that the buffer will
277 		 * be large enough to cope with a message length of
278 		 * I2C_SMBUS_BLOCK_MAX as this is the maximum underlying bus
279 		 * drivers allow. The first byte in the buffer must be
280 		 * pre-filled with the number of extra bytes, which must be
281 		 * at least one to hold the message length, but can be
282 		 * greater (for example to account for a checksum byte at
283 		 * the end of the message.)
284 		 */
285 		if (msgs[i].flags & I2C_M_RECV_LEN) {
286 			if (!(msgs[i].flags & I2C_M_RD) ||
287 			    msgs[i].len < 1 || msgs[i].buf[0] < 1 ||
288 			    msgs[i].len < msgs[i].buf[0] +
289 					     I2C_SMBUS_BLOCK_MAX) {
290 				i++;
291 				res = -EINVAL;
292 				break;
293 			}
294 
295 			msgs[i].len = msgs[i].buf[0];
296 		}
297 	}
298 	if (res < 0) {
299 		int j;
300 		for (j = 0; j < i; ++j)
301 			kfree(msgs[j].buf);
302 		kfree(data_ptrs);
303 		return res;
304 	}
305 
306 	res = i2c_transfer(client->adapter, msgs, nmsgs);
307 	while (i-- > 0) {
308 		if (res >= 0 && (msgs[i].flags & I2C_M_RD)) {
309 			if (copy_to_user(data_ptrs[i], msgs[i].buf,
310 					 msgs[i].len))
311 				res = -EFAULT;
312 		}
313 		kfree(msgs[i].buf);
314 	}
315 	kfree(data_ptrs);
316 	return res;
317 }
318 
i2cdev_ioctl_smbus(struct i2c_client * client,u8 read_write,u8 command,u32 size,union i2c_smbus_data __user * data)319 static noinline int i2cdev_ioctl_smbus(struct i2c_client *client,
320 		u8 read_write, u8 command, u32 size,
321 		union i2c_smbus_data __user *data)
322 {
323 	union i2c_smbus_data temp = {};
324 	int datasize, res;
325 
326 	if ((size != I2C_SMBUS_BYTE) &&
327 	    (size != I2C_SMBUS_QUICK) &&
328 	    (size != I2C_SMBUS_BYTE_DATA) &&
329 	    (size != I2C_SMBUS_WORD_DATA) &&
330 	    (size != I2C_SMBUS_PROC_CALL) &&
331 	    (size != I2C_SMBUS_BLOCK_DATA) &&
332 	    (size != I2C_SMBUS_I2C_BLOCK_BROKEN) &&
333 	    (size != I2C_SMBUS_I2C_BLOCK_DATA) &&
334 	    (size != I2C_SMBUS_BLOCK_PROC_CALL)) {
335 		dev_dbg(&client->adapter->dev,
336 			"size out of range (%x) in ioctl I2C_SMBUS.\n",
337 			size);
338 		return -EINVAL;
339 	}
340 	/* Note that I2C_SMBUS_READ and I2C_SMBUS_WRITE are 0 and 1,
341 	   so the check is valid if size==I2C_SMBUS_QUICK too. */
342 	if ((read_write != I2C_SMBUS_READ) &&
343 	    (read_write != I2C_SMBUS_WRITE)) {
344 		dev_dbg(&client->adapter->dev,
345 			"read_write out of range (%x) in ioctl I2C_SMBUS.\n",
346 			read_write);
347 		return -EINVAL;
348 	}
349 
350 	/* Note that command values are always valid! */
351 
352 	if ((size == I2C_SMBUS_QUICK) ||
353 	    ((size == I2C_SMBUS_BYTE) &&
354 	    (read_write == I2C_SMBUS_WRITE)))
355 		/* These are special: we do not use data */
356 		return i2c_smbus_xfer(client->adapter, client->addr,
357 				      client->flags, read_write,
358 				      command, size, NULL);
359 
360 	if (data == NULL) {
361 		dev_dbg(&client->adapter->dev,
362 			"data is NULL pointer in ioctl I2C_SMBUS.\n");
363 		return -EINVAL;
364 	}
365 
366 	if ((size == I2C_SMBUS_BYTE_DATA) ||
367 	    (size == I2C_SMBUS_BYTE))
368 		datasize = sizeof(data->byte);
369 	else if ((size == I2C_SMBUS_WORD_DATA) ||
370 		 (size == I2C_SMBUS_PROC_CALL))
371 		datasize = sizeof(data->word);
372 	else /* size == smbus block, i2c block, or block proc. call */
373 		datasize = sizeof(data->block);
374 
375 	if ((size == I2C_SMBUS_PROC_CALL) ||
376 	    (size == I2C_SMBUS_BLOCK_PROC_CALL) ||
377 	    (size == I2C_SMBUS_I2C_BLOCK_DATA) ||
378 	    (read_write == I2C_SMBUS_WRITE)) {
379 		if (copy_from_user(&temp, data, datasize))
380 			return -EFAULT;
381 	}
382 	if (size == I2C_SMBUS_I2C_BLOCK_BROKEN) {
383 		/* Convert old I2C block commands to the new
384 		   convention. This preserves binary compatibility. */
385 		size = I2C_SMBUS_I2C_BLOCK_DATA;
386 		if (read_write == I2C_SMBUS_READ)
387 			temp.block[0] = I2C_SMBUS_BLOCK_MAX;
388 	}
389 	res = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
390 	      read_write, command, size, &temp);
391 	if (!res && ((size == I2C_SMBUS_PROC_CALL) ||
392 		     (size == I2C_SMBUS_BLOCK_PROC_CALL) ||
393 		     (read_write == I2C_SMBUS_READ))) {
394 		if (copy_to_user(data, &temp, datasize))
395 			return -EFAULT;
396 	}
397 	return res;
398 }
399 
i2cdev_ioctl(struct file * file,unsigned int cmd,unsigned long arg)400 static long i2cdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
401 {
402 	struct i2c_client *client = file->private_data;
403 	unsigned long funcs;
404 
405 	dev_dbg(&client->adapter->dev, "ioctl, cmd=0x%02x, arg=0x%02lx\n",
406 		cmd, arg);
407 
408 	switch (cmd) {
409 	case I2C_SLAVE:
410 	case I2C_SLAVE_FORCE:
411 		if ((arg > 0x3ff) ||
412 		    (((client->flags & I2C_M_TEN) == 0) && arg > 0x7f))
413 			return -EINVAL;
414 		if (cmd == I2C_SLAVE && i2cdev_check_addr(client->adapter, arg))
415 			return -EBUSY;
416 		/* REVISIT: address could become busy later */
417 		client->addr = arg;
418 		return 0;
419 	case I2C_TENBIT:
420 		if (arg)
421 			client->flags |= I2C_M_TEN;
422 		else
423 			client->flags &= ~I2C_M_TEN;
424 		return 0;
425 	case I2C_PEC:
426 		/*
427 		 * Setting the PEC flag here won't affect kernel drivers,
428 		 * which will be using the i2c_client node registered with
429 		 * the driver model core.  Likewise, when that client has
430 		 * the PEC flag already set, the i2c-dev driver won't see
431 		 * (or use) this setting.
432 		 */
433 		if (arg)
434 			client->flags |= I2C_CLIENT_PEC;
435 		else
436 			client->flags &= ~I2C_CLIENT_PEC;
437 		return 0;
438 	case I2C_FUNCS:
439 		funcs = i2c_get_functionality(client->adapter);
440 		return put_user(funcs, (unsigned long __user *)arg);
441 
442 	case I2C_RDWR: {
443 		struct i2c_rdwr_ioctl_data rdwr_arg;
444 		struct i2c_msg *rdwr_pa;
445 		int res;
446 
447 		if (copy_from_user(&rdwr_arg,
448 				   (struct i2c_rdwr_ioctl_data __user *)arg,
449 				   sizeof(rdwr_arg)))
450 			return -EFAULT;
451 
452 		if (!rdwr_arg.msgs || rdwr_arg.nmsgs == 0)
453 			return -EINVAL;
454 
455 		/*
456 		 * Put an arbitrary limit on the number of messages that can
457 		 * be sent at once
458 		 */
459 		if (rdwr_arg.nmsgs > I2C_RDWR_IOCTL_MAX_MSGS)
460 			return -EINVAL;
461 
462 		rdwr_pa = memdup_array_user(rdwr_arg.msgs,
463 					    rdwr_arg.nmsgs, sizeof(struct i2c_msg));
464 		if (IS_ERR(rdwr_pa))
465 			return PTR_ERR(rdwr_pa);
466 
467 		res = i2cdev_ioctl_rdwr(client, rdwr_arg.nmsgs, rdwr_pa);
468 		kfree(rdwr_pa);
469 		return res;
470 	}
471 
472 	case I2C_SMBUS: {
473 		struct i2c_smbus_ioctl_data data_arg;
474 		if (copy_from_user(&data_arg,
475 				   (struct i2c_smbus_ioctl_data __user *) arg,
476 				   sizeof(struct i2c_smbus_ioctl_data)))
477 			return -EFAULT;
478 		return i2cdev_ioctl_smbus(client, data_arg.read_write,
479 					  data_arg.command,
480 					  data_arg.size,
481 					  data_arg.data);
482 	}
483 	case I2C_RETRIES:
484 		if (arg > INT_MAX)
485 			return -EINVAL;
486 
487 		client->adapter->retries = arg;
488 		break;
489 	case I2C_TIMEOUT:
490 		if (arg > INT_MAX)
491 			return -EINVAL;
492 
493 		/* For historical reasons, user-space sets the timeout
494 		 * value in units of 10 ms.
495 		 */
496 		client->adapter->timeout = msecs_to_jiffies(arg * 10);
497 		break;
498 	default:
499 		/* NOTE:  returning a fault code here could cause trouble
500 		 * in buggy userspace code.  Some old kernel bugs returned
501 		 * zero in this case, and userspace code might accidentally
502 		 * have depended on that bug.
503 		 */
504 		return -ENOTTY;
505 	}
506 	return 0;
507 }
508 
509 #ifdef CONFIG_COMPAT
510 
511 struct i2c_smbus_ioctl_data32 {
512 	u8 read_write;
513 	u8 command;
514 	u32 size;
515 	compat_caddr_t data; /* union i2c_smbus_data *data */
516 };
517 
518 struct i2c_msg32 {
519 	u16 addr;
520 	u16 flags;
521 	u16 len;
522 	compat_caddr_t buf;
523 };
524 
525 struct i2c_rdwr_ioctl_data32 {
526 	compat_caddr_t msgs; /* struct i2c_msg __user *msgs */
527 	u32 nmsgs;
528 };
529 
compat_i2cdev_ioctl(struct file * file,unsigned int cmd,unsigned long arg)530 static long compat_i2cdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
531 {
532 	struct i2c_client *client = file->private_data;
533 	unsigned long funcs;
534 	switch (cmd) {
535 	case I2C_FUNCS:
536 		funcs = i2c_get_functionality(client->adapter);
537 		return put_user(funcs, (compat_ulong_t __user *)arg);
538 	case I2C_RDWR: {
539 		struct i2c_rdwr_ioctl_data32 rdwr_arg;
540 		struct i2c_msg32 __user *p;
541 		struct i2c_msg *rdwr_pa;
542 		int i, res;
543 
544 		if (copy_from_user(&rdwr_arg,
545 				   (struct i2c_rdwr_ioctl_data32 __user *)arg,
546 				   sizeof(rdwr_arg)))
547 			return -EFAULT;
548 
549 		if (!rdwr_arg.msgs || rdwr_arg.nmsgs == 0)
550 			return -EINVAL;
551 
552 		if (rdwr_arg.nmsgs > I2C_RDWR_IOCTL_MAX_MSGS)
553 			return -EINVAL;
554 
555 		rdwr_pa = kmalloc_array(rdwr_arg.nmsgs, sizeof(struct i2c_msg),
556 				      GFP_KERNEL);
557 		if (!rdwr_pa)
558 			return -ENOMEM;
559 
560 		p = compat_ptr(rdwr_arg.msgs);
561 		for (i = 0; i < rdwr_arg.nmsgs; i++) {
562 			struct i2c_msg32 umsg;
563 			if (copy_from_user(&umsg, p + i, sizeof(umsg))) {
564 				kfree(rdwr_pa);
565 				return -EFAULT;
566 			}
567 			rdwr_pa[i] = (struct i2c_msg) {
568 				.addr = umsg.addr,
569 				.flags = umsg.flags,
570 				.len = umsg.len,
571 				.buf = (__force __u8 *)compat_ptr(umsg.buf),
572 			};
573 		}
574 
575 		res = i2cdev_ioctl_rdwr(client, rdwr_arg.nmsgs, rdwr_pa);
576 		kfree(rdwr_pa);
577 		return res;
578 	}
579 	case I2C_SMBUS: {
580 		struct i2c_smbus_ioctl_data32	data32;
581 		if (copy_from_user(&data32,
582 				   (void __user *) arg,
583 				   sizeof(data32)))
584 			return -EFAULT;
585 		return i2cdev_ioctl_smbus(client, data32.read_write,
586 					  data32.command,
587 					  data32.size,
588 					  compat_ptr(data32.data));
589 	}
590 	default:
591 		return i2cdev_ioctl(file, cmd, arg);
592 	}
593 }
594 #else
595 #define compat_i2cdev_ioctl NULL
596 #endif
597 
i2cdev_open(struct inode * inode,struct file * file)598 static int i2cdev_open(struct inode *inode, struct file *file)
599 {
600 	unsigned int minor = iminor(inode);
601 	struct i2c_client *client;
602 	struct i2c_adapter *adap;
603 
604 	adap = i2c_get_adapter(minor);
605 	if (!adap)
606 		return -ENODEV;
607 
608 	/* This creates an anonymous i2c_client, which may later be
609 	 * pointed to some address using I2C_SLAVE or I2C_SLAVE_FORCE.
610 	 *
611 	 * This client is ** NEVER REGISTERED ** with the driver model
612 	 * or I2C core code!!  It just holds private copies of addressing
613 	 * information and maybe a PEC flag.
614 	 */
615 	client = kzalloc(sizeof(*client), GFP_KERNEL);
616 	if (!client) {
617 		i2c_put_adapter(adap);
618 		return -ENOMEM;
619 	}
620 	snprintf(client->name, I2C_NAME_SIZE, "i2c-dev %d", adap->nr);
621 
622 	client->adapter = adap;
623 	file->private_data = client;
624 
625 	return 0;
626 }
627 
i2cdev_release(struct inode * inode,struct file * file)628 static int i2cdev_release(struct inode *inode, struct file *file)
629 {
630 	struct i2c_client *client = file->private_data;
631 
632 	i2c_put_adapter(client->adapter);
633 	kfree(client);
634 	file->private_data = NULL;
635 
636 	return 0;
637 }
638 
639 static const struct file_operations i2cdev_fops = {
640 	.owner		= THIS_MODULE,
641 	.read		= i2cdev_read,
642 	.write		= i2cdev_write,
643 	.unlocked_ioctl	= i2cdev_ioctl,
644 	.compat_ioctl	= compat_i2cdev_ioctl,
645 	.open		= i2cdev_open,
646 	.release	= i2cdev_release,
647 };
648 
649 /* ------------------------------------------------------------------------- */
650 
651 static const struct class i2c_dev_class = {
652 	.name = "i2c-dev",
653 	.dev_groups = i2c_groups,
654 };
655 
i2cdev_dev_release(struct device * dev)656 static void i2cdev_dev_release(struct device *dev)
657 {
658 	struct i2c_dev *i2c_dev;
659 
660 	i2c_dev = container_of(dev, struct i2c_dev, dev);
661 	kfree(i2c_dev);
662 }
663 
i2cdev_attach_adapter(struct device * dev)664 static int i2cdev_attach_adapter(struct device *dev)
665 {
666 	struct i2c_adapter *adap;
667 	struct i2c_dev *i2c_dev;
668 	int res;
669 
670 	if (dev->type != &i2c_adapter_type)
671 		return NOTIFY_DONE;
672 	adap = to_i2c_adapter(dev);
673 
674 	i2c_dev = get_free_i2c_dev(adap);
675 	if (IS_ERR(i2c_dev))
676 		return NOTIFY_DONE;
677 
678 	cdev_init(&i2c_dev->cdev, &i2cdev_fops);
679 	i2c_dev->cdev.owner = THIS_MODULE;
680 
681 	device_initialize(&i2c_dev->dev);
682 	i2c_dev->dev.devt = MKDEV(I2C_MAJOR, adap->nr);
683 	i2c_dev->dev.class = &i2c_dev_class;
684 	i2c_dev->dev.parent = &adap->dev;
685 	i2c_dev->dev.release = i2cdev_dev_release;
686 
687 	res = dev_set_name(&i2c_dev->dev, "i2c-%d", adap->nr);
688 	if (res)
689 		goto err_put_i2c_dev;
690 
691 	res = cdev_device_add(&i2c_dev->cdev, &i2c_dev->dev);
692 	if (res)
693 		goto err_put_i2c_dev;
694 
695 	pr_debug("adapter [%s] registered as minor %d\n", adap->name, adap->nr);
696 	return NOTIFY_OK;
697 
698 err_put_i2c_dev:
699 	put_i2c_dev(i2c_dev, false);
700 	return NOTIFY_DONE;
701 }
702 
i2cdev_detach_adapter(struct device * dev)703 static int i2cdev_detach_adapter(struct device *dev)
704 {
705 	struct i2c_adapter *adap;
706 	struct i2c_dev *i2c_dev;
707 
708 	if (dev->type != &i2c_adapter_type)
709 		return NOTIFY_DONE;
710 	adap = to_i2c_adapter(dev);
711 
712 	i2c_dev = i2c_dev_get_by_minor(adap->nr);
713 	if (!i2c_dev) /* attach_adapter must have failed */
714 		return NOTIFY_DONE;
715 
716 	put_i2c_dev(i2c_dev, true);
717 
718 	pr_debug("adapter [%s] unregistered\n", adap->name);
719 	return NOTIFY_OK;
720 }
721 
i2cdev_notifier_call(struct notifier_block * nb,unsigned long action,void * data)722 static int i2cdev_notifier_call(struct notifier_block *nb, unsigned long action,
723 			 void *data)
724 {
725 	struct device *dev = data;
726 
727 	switch (action) {
728 	case BUS_NOTIFY_ADD_DEVICE:
729 		return i2cdev_attach_adapter(dev);
730 	case BUS_NOTIFY_DEL_DEVICE:
731 		return i2cdev_detach_adapter(dev);
732 	}
733 
734 	return NOTIFY_DONE;
735 }
736 
737 static struct notifier_block i2cdev_notifier = {
738 	.notifier_call = i2cdev_notifier_call,
739 };
740 
741 /* ------------------------------------------------------------------------- */
742 
i2c_dev_attach_adapter(struct device * dev,void * dummy)743 static int __init i2c_dev_attach_adapter(struct device *dev, void *dummy)
744 {
745 	i2cdev_attach_adapter(dev);
746 	return 0;
747 }
748 
i2c_dev_detach_adapter(struct device * dev,void * dummy)749 static int __exit i2c_dev_detach_adapter(struct device *dev, void *dummy)
750 {
751 	i2cdev_detach_adapter(dev);
752 	return 0;
753 }
754 
755 /*
756  * module load/unload record keeping
757  */
758 
i2c_dev_init(void)759 static int __init i2c_dev_init(void)
760 {
761 	int res;
762 
763 	pr_info("i2c /dev entries driver\n");
764 
765 	res = register_chrdev_region(MKDEV(I2C_MAJOR, 0), I2C_MINORS, "i2c");
766 	if (res)
767 		goto out;
768 
769 	res = class_register(&i2c_dev_class);
770 	if (res)
771 		goto out_unreg_chrdev;
772 
773 	/* Keep track of adapters which will be added or removed later */
774 	res = bus_register_notifier(&i2c_bus_type, &i2cdev_notifier);
775 	if (res)
776 		goto out_unreg_class;
777 
778 	/* Bind to already existing adapters right away */
779 	i2c_for_each_dev(NULL, i2c_dev_attach_adapter);
780 
781 	return 0;
782 
783 out_unreg_class:
784 	class_unregister(&i2c_dev_class);
785 out_unreg_chrdev:
786 	unregister_chrdev_region(MKDEV(I2C_MAJOR, 0), I2C_MINORS);
787 out:
788 	pr_err("Driver Initialisation failed\n");
789 	return res;
790 }
791 
i2c_dev_exit(void)792 static void __exit i2c_dev_exit(void)
793 {
794 	bus_unregister_notifier(&i2c_bus_type, &i2cdev_notifier);
795 	i2c_for_each_dev(NULL, i2c_dev_detach_adapter);
796 	class_unregister(&i2c_dev_class);
797 	unregister_chrdev_region(MKDEV(I2C_MAJOR, 0), I2C_MINORS);
798 }
799 
800 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl>");
801 MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>");
802 MODULE_DESCRIPTION("I2C /dev entries driver");
803 MODULE_LICENSE("GPL");
804 
805 module_init(i2c_dev_init);
806 module_exit(i2c_dev_exit);
807