aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/i2c/i2c-dev.c
blob: c21ae20ae362b059a2c347238f0e063616e0411e (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
/*
    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.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

/* 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/kernel.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/i2c.h>
#include <linux/i2c-dev.h>
#include <asm/uaccess.h>

static struct i2c_driver i2cdev_driver;

/*
 * 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 notifications
 * delivered to the i2cdev_driver.
 */
struct i2c_dev {
	struct list_head list;
	struct i2c_adapter *adap;
	struct device *dev;
};

#define I2C_MINORS	256
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 return_i2c_dev(struct i2c_dev *i2c_dev)
{
	spin_lock(&i2c_dev_list_lock);
	list_del(&i2c_dev->list);
	spin_unlock(&i2c_dev_list_lock);
	kfree(i2c_dev);
}

static ssize_t show_adapter_name(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(name, S_IRUGO, show_adapter_name, NULL);

/* ------------------------------------------------------------------------- */

/*
 * 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 = (struct i2c_client *)file->private_data;

	if (count > 8192)
		count = 8192;

	tmp = kmalloc(count,GFP_KERNEL);
	if (tmp==NULL)
		return -ENOMEM;

	pr_debug("i2c-dev: i2c-%d reading %zd bytes.\n",
		iminor(file->f_path.dentry->d_inode), count);

	ret = i2c_master_recv(client,tmp,count);
	if (ret >= 0)
		ret = copy_to_user(buf,tmp,count)?-EFAULT:ret;
	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 = (struct i2c_client *)file->private_data;

	if (count > 8192)
		count = 8192;

	tmp = kmalloc(count,GFP_KERNEL);
	if (tmp==NULL)
		return -ENOMEM;
	if (copy_from_user(tmp,buf,count)) {
		kfree(tmp);
		return -EFAULT;
	}

	pr_debug("i2c-dev: i2c-%d writing %zd bytes.\n",
		iminor(file->f_path.dentry->d_inode), count);

	ret = i2c_master_send(client,tmp,count);
	kfree(tmp);
	return ret;
}

/* This address checking function differs from the one in i2c-core
   in that it considers an address with a registered device, but no
   bounded driver, as NOT busy. */
static int i2cdev_check_addr(struct i2c_adapter *adapter, unsigned int addr)
{
	struct list_head *item;
	struct i2c_client *client;
	int res = 0;

	mutex_lock(&adapter->clist_lock);
	list_for_each(item, &adapter->clients) {
		client = list_entry(item, struct i2c_client, list);
		if (client->addr == addr) {
			if (client->driver)
				res = -EBUSY;
			break;
		}
	}
	mutex_unlock(&adapter->clist_lock);

	return res;
}

static int i2cdev_ioctl(struct inode *inode, struct file *file,
		unsigned int cmd, unsigned long arg)
{
	struct i2c_client *client = (struct i2c_client *)file->private_data;
	struct i2c_rdwr_ioctl_data rdwr_arg;
	struct i2c_smbus_ioctl_data data_arg;
	union i2c_smbus_data temp;
	struct i2c_msg *rdwr_pa;
	u8 __user **data_ptrs;
	int i,datasize,res;
	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:
		/* NOTE:  devices set up to work with "new style" drivers
		 * can't use I2C_SLAVE, even when the device node is not
		 * bound to a driver.  Only I2C_SLAVE_FORCE will work.
		 *
		 * 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 > 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:
		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:
		if (copy_from_user(&rdwr_arg,
				   (struct i2c_rdwr_ioctl_data __user *)arg,
				   sizeof(rdwr_arg)))
			return -EFAULT;

		/* Put an arbitrary limit on the number of messages that can
		 * be sent at once */
		if (rdwr_arg.nmsgs > I2C_RDRW_IOCTL_MAX_MSGS)
			return -EINVAL;

		rdwr_pa = (struct i2c_msg *)
			kmalloc(rdwr_arg.nmsgs * sizeof(struct i2c_msg),
			GFP_KERNEL);

		if (rdwr_pa == NULL) return -ENOMEM;

		if (copy_from_user(rdwr_pa, rdwr_arg.msgs,
				   rdwr_arg.nmsgs * sizeof(struct i2c_msg))) {
			kfree(rdwr_pa);
			return -EFAULT;
		}

		data_ptrs = kmalloc(rdwr_arg.nmsgs * sizeof(u8 __user *), GFP_KERNEL);
		if (data_ptrs == NULL) {
			kfree(rdwr_pa);
			return -ENOMEM;
		}

		res = 0;
		for( i=0; i<rdwr_arg.nmsgs; i++ ) {
			/* Limit the size of the message to a sane amount;
			 * and don't let length change either. */
			if ((rdwr_pa[i].len > 8192) ||
			    (rdwr_pa[i].flags & I2C_M_RECV_LEN)) {
				res = -EINVAL;
				break;
			}
			data_ptrs[i] = (u8 __user *)rdwr_pa[i].buf;
			rdwr_pa[i].buf = kmalloc(rdwr_pa[i].len, GFP_KERNEL);
			if(rdwr_pa[i].buf == NULL) {
				res = -ENOMEM;
				break;
			}
			if(copy_from_user(rdwr_pa[i].buf,
				data_ptrs[i],
				rdwr_pa[i].len)) {
					++i; /* Needs to be kfreed too */
					res = -EFAULT;
				break;
			}
		}
		if (res < 0) {
			int j;
			for (j = 0; j < i; ++j)
				kfree(rdwr_pa[j].buf);
			kfree(data_ptrs);
			kfree(rdwr_pa);
			return res;
		}

		res = i2c_transfer(client->adapter,
			rdwr_pa,
			rdwr_arg.nmsgs);
		while(i-- > 0) {
			if( res>=0 && (rdwr_pa[i].flags & I2C_M_RD)) {
				if(copy_to_user(
					data_ptrs[i],
					rdwr_pa[i].buf,
					rdwr_pa[i].len)) {
					res = -EFAULT;
				}
			}
			kfree(rdwr_pa[i].buf);
		}
		kfree(data_ptrs);
		kfree(rdwr_pa);
		return res;

	case I2C_SMBUS:
		if (copy_from_user(&data_arg,
		                   (struct i2c_smbus_ioctl_data __user *) arg,
		                   sizeof(struct i2c_smbus_ioctl_data)))
			return -EFAULT;
		if ((data_arg.size != I2C_SMBUS_BYTE) &&
		    (data_arg.size != I2C_SMBUS_QUICK) &&
		    (data_arg.size != I2C_SMBUS_BYTE_DATA) &&
		    (data_arg.size != I2C_SMBUS_WORD_DATA) &&
		    (data_arg.size != I2C_SMBUS_PROC_CALL) &&
		    (data_arg.size != I2C_SMBUS_BLOCK_DATA) &&
		    (data_arg.size != I2C_SMBUS_I2C_BLOCK_BROKEN) &&
		    (data_arg.size != I2C_SMBUS_I2C_BLOCK_DATA) &&
		    (data_arg.size != I2C_SMBUS_BLOCK_PROC_CALL)) {
			dev_dbg(&client->adapter->dev,
				"size out of range (%x) in ioctl I2C_SMBUS.\n",
				data_arg.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 ((data_arg.read_write != I2C_SMBUS_READ) &&
		    (data_arg.read_write != I2C_SMBUS_WRITE)) {
			dev_dbg(&client->adapter->dev,
				"read_write out of range (%x) in ioctl I2C_SMBUS.\n",
				data_arg.read_write);
			return -EINVAL;
		}

		/* Note that command values are always valid! */

		if ((data_arg.size == I2C_SMBUS_QUICK) ||
		    ((data_arg.size == I2C_SMBUS_BYTE) &&
		    (data_arg.read_write == I2C_SMBUS_WRITE)))
			/* These are special: we do not use data */
			return i2c_smbus_xfer(client->adapter, client->addr,
					      client->flags,
					      data_arg.read_write,
					      data_arg.command,
					      data_arg.size, NULL);

		if (data_arg.data == NULL) {
			dev_dbg(&client->adapter->dev,
				"data is NULL pointer in ioctl I2C_SMBUS.\n");
			return -EINVAL;
		}

		if ((data_arg.size == I2C_SMBUS_BYTE_DATA) ||
		    (data_arg.size == I2C_SMBUS_BYTE))
			datasize = sizeof(data_arg.data->byte);
		else if ((data_arg.size == I2C_SMBUS_WORD_DATA) ||
		         (data_arg.size == I2C_SMBUS_PROC_CALL))
			datasize = sizeof(data_arg.data->word);
		else /* size == smbus block, i2c block, or block proc. call */
			datasize = sizeof(data_arg.data->block);

		if ((data_arg.size == I2C_SMBUS_PROC_CALL) ||
		    (data_arg.size == I2C_SMBUS_BLOCK_PROC_CALL) ||
		    (data_arg.size == I2C_SMBUS_I2C_BLOCK_DATA) ||
		    (data_arg.read_write == I2C_SMBUS_WRITE)) {
			if (copy_from_user(&temp, data_arg.data, datasize))
				return -EFAULT;
		}
		if (data_arg.size == I2C_SMBUS_I2C_BLOCK_BROKEN) {
			/* Convert old I2C block commands to the new
			   convention. This preserves binary compatibility. */
			data_arg.size = I2C_SMBUS_I2C_BLOCK_DATA;
			if (data_arg.read_write == I2C_SMBUS_READ)
				temp.block[0] = I2C_SMBUS_BLOCK_MAX;
		}
		res = i2c_smbus_xfer(client->adapter,client->addr,client->flags,
		      data_arg.read_write,
		      data_arg.command,data_arg.size,&temp);
		if (! res && ((data_arg.size == I2C_SMBUS_PROC_CALL) ||
		              (data_arg.size == I2C_SMBUS_BLOCK_PROC_CALL) ||
			      (data_arg.read_write == I2C_SMBUS_READ))) {
			if (copy_to_user(data_arg.data, &temp, datasize))
				return -EFAULT;
		}
		return res;
	case I2C_RETRIES:
		client->adapter->retries = arg;
		break;
	case I2C_TIMEOUT:
		client->adapter->timeout = arg;
		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;
}

static int i2cdev_open(struct inode *inode, struct file *file)
{
	unsigned int minor = iminor(inode);
	struct i2c_client *client;
	struct i2c_adapter *adap;
	struct i2c_dev *i2c_dev;

	i2c_dev = i2c_dev_get_by_minor(minor);
	if (!i2c_dev)
		return -ENODEV;

	adap = i2c_get_adapter(i2c_dev->adap->nr);
	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->driver = &i2cdev_driver;

	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,
	.ioctl		= i2cdev_ioctl,
	.open		= i2cdev_open,
	.release	= i2cdev_release,
};

/* ------------------------------------------------------------------------- */

/*
 * The legacy "i2cdev_driver" is used primarily to get notifications when
 * I2C adapters are added or removed, so that each one gets an i2c_dev
 * and is thus made available to userspace driver code.
 */

static struct class *i2c_dev_class;

static int i2cdev_attach_adapter(struct i2c_adapter *adap)
{
	struct i2c_dev *i2c_dev;
	int res;

	i2c_dev = get_free_i2c_dev(adap);
	if (IS_ERR(i2c_dev))
		return PTR_ERR(i2c_dev);

	/* register this i2c device with the driver core */
	i2c_dev->dev = device_create(i2c_dev_class, &adap->dev,
				     MKDEV(I2C_MAJOR, adap->nr),
				     "i2c-%d", adap->nr);
	if (IS_ERR(i2c_dev->dev)) {
		res = PTR_ERR(i2c_dev->dev);
		goto error;
	}
	res = device_create_file(i2c_dev->dev, &dev_attr_name);
	if (res)
		goto error_destroy;

	pr_debug("i2c-dev: adapter [%s] registered as minor %d\n",
		 adap->name, adap->nr);
	return 0;
error_destroy:
	device_destroy(i2c_dev_class, MKDEV(I2C_MAJOR, adap->nr));
error:
	return_i2c_dev(i2c_dev);
	return res;
}

static int i2cdev_detach_adapter(struct i2c_adapter *adap)
{
	struct i2c_dev *i2c_dev;

	i2c_dev = i2c_dev_get_by_minor(adap->nr);
	if (!i2c_dev) /* attach_adapter must have failed */
		return 0;

	device_remove_file(i2c_dev->dev, &dev_attr_name);
	return_i2c_dev(i2c_dev);
	device_destroy(i2c_dev_class, MKDEV(I2C_MAJOR, adap->nr));

	pr_debug("i2c-dev: adapter [%s] unregistered\n", adap->name);
	return 0;
}

static int i2cdev_detach_client(struct i2c_client *client)
{
	return 0;
}

static struct i2c_driver i2cdev_driver = {
	.driver = {
		.name	= "dev_driver",
	},
	.id		= I2C_DRIVERID_I2CDEV,
	.attach_adapter	= i2cdev_attach_adapter,
	.detach_adapter	= i2cdev_detach_adapter,
	.detach_client	= i2cdev_detach_client,
};

/* ------------------------------------------------------------------------- */

/*
 * 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(I2C_MAJOR, "i2c", &i2cdev_fops);
	if (res)
		goto out;

	i2c_dev_class = class_create(THIS_MODULE, "i2c-dev");
	if (IS_ERR(i2c_dev_class))
		goto out_unreg_chrdev;

	res = i2c_add_driver(&i2cdev_driver);
	if (res)
		goto out_unreg_class;

	return 0;

out_unreg_class:
	class_destroy(i2c_dev_class);
out_unreg_chrdev:
	unregister_chrdev(I2C_MAJOR, "i2c");
out:
	printk(KERN_ERR "%s: Driver Initialisation failed\n", __FILE__);
	return res;
}

static void __exit i2c_dev_exit(void)
{
	i2c_del_driver(&i2cdev_driver);
	class_destroy(i2c_dev_class);
	unregister_chrdev(I2C_MAJOR,"i2c");
}

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);