2 i2c-dev.c - i2c-bus driver, char device interface
4 Copyright (C) 1995-97 Simon G. Vogl
5 Copyright (C) 1998-99 Frodo Looijaard <frodol@dds.nl>
6 Copyright (C) 2003 Greg Kroah-Hartman <greg@kroah.com>
8 This program is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 2 of the License, or
11 (at your option) any later version.
13 This program is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with this program; if not, write to the Free Software
20 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
23 /* Note that this is a complete rewrite of Simon Vogl's i2c-dev module.
24 But I have used so much of his original code and ideas that it seems
25 only fair to recognize him as co-author -- Frodo */
27 /* The I2C_RDWR ioctl code is written by Kolja Waschk <waschk@telos.de> */
29 #include <linux/kernel.h>
30 #include <linux/module.h>
32 #include <linux/slab.h>
33 #include <linux/init.h>
34 #include <linux/list.h>
35 #include <linux/i2c.h>
36 #include <linux/i2c-dev.h>
37 #include <linux/smp_lock.h>
38 #include <linux/jiffies.h>
39 #include <asm/uaccess.h>
41 static struct i2c_driver i2cdev_driver;
44 * An i2c_dev represents an i2c_adapter ... an I2C or SMBus master, not a
45 * slave (i2c_client) with which messages will be exchanged. It's coupled
46 * with a character special file which is accessed by user mode drivers.
48 * The list of i2c_dev structures is parallel to the i2c_adapter lists
49 * maintained by the driver model, and is updated using notifications
50 * delivered to the i2cdev_driver.
53 struct list_head list;
54 struct i2c_adapter *adap;
58 #define I2C_MINORS 256
59 static LIST_HEAD(i2c_dev_list);
60 static DEFINE_SPINLOCK(i2c_dev_list_lock);
62 static struct i2c_dev *i2c_dev_get_by_minor(unsigned index)
64 struct i2c_dev *i2c_dev;
66 spin_lock(&i2c_dev_list_lock);
67 list_for_each_entry(i2c_dev, &i2c_dev_list, list) {
68 if (i2c_dev->adap->nr == index)
73 spin_unlock(&i2c_dev_list_lock);
77 static struct i2c_dev *get_free_i2c_dev(struct i2c_adapter *adap)
79 struct i2c_dev *i2c_dev;
81 if (adap->nr >= I2C_MINORS) {
82 printk(KERN_ERR "i2c-dev: Out of device minors (%d)\n",
84 return ERR_PTR(-ENODEV);
87 i2c_dev = kzalloc(sizeof(*i2c_dev), GFP_KERNEL);
89 return ERR_PTR(-ENOMEM);
92 spin_lock(&i2c_dev_list_lock);
93 list_add_tail(&i2c_dev->list, &i2c_dev_list);
94 spin_unlock(&i2c_dev_list_lock);
98 static void return_i2c_dev(struct i2c_dev *i2c_dev)
100 spin_lock(&i2c_dev_list_lock);
101 list_del(&i2c_dev->list);
102 spin_unlock(&i2c_dev_list_lock);
106 static ssize_t show_adapter_name(struct device *dev,
107 struct device_attribute *attr, char *buf)
109 struct i2c_dev *i2c_dev = i2c_dev_get_by_minor(MINOR(dev->devt));
113 return sprintf(buf, "%s\n", i2c_dev->adap->name);
115 static DEVICE_ATTR(name, S_IRUGO, show_adapter_name, NULL);
117 /* ------------------------------------------------------------------------- */
120 * After opening an instance of this character special file, a file
121 * descriptor starts out associated only with an i2c_adapter (and bus).
123 * Using the I2C_RDWR ioctl(), you can then *immediately* issue i2c_msg
124 * traffic to any devices on the bus used by that adapter. That's because
125 * the i2c_msg vectors embed all the addressing information they need, and
126 * are submitted directly to an i2c_adapter. However, SMBus-only adapters
127 * don't support that interface.
129 * To use read()/write() system calls on that file descriptor, or to use
130 * SMBus interfaces (and work with SMBus-only hosts!), you must first issue
131 * an I2C_SLAVE (or I2C_SLAVE_FORCE) ioctl. That configures an anonymous
132 * (never registered) i2c_client so it holds the addressing information
133 * needed by those system calls and by this SMBus interface.
136 static ssize_t i2cdev_read (struct file *file, char __user *buf, size_t count,
142 struct i2c_client *client = (struct i2c_client *)file->private_data;
147 tmp = kmalloc(count,GFP_KERNEL);
151 pr_debug("i2c-dev: i2c-%d reading %zu bytes.\n",
152 iminor(file->f_path.dentry->d_inode), count);
154 ret = i2c_master_recv(client,tmp,count);
156 ret = copy_to_user(buf,tmp,count)?-EFAULT:ret;
161 static ssize_t i2cdev_write (struct file *file, const char __user *buf, size_t count,
166 struct i2c_client *client = (struct i2c_client *)file->private_data;
171 tmp = kmalloc(count,GFP_KERNEL);
174 if (copy_from_user(tmp,buf,count)) {
179 pr_debug("i2c-dev: i2c-%d writing %zu bytes.\n",
180 iminor(file->f_path.dentry->d_inode), count);
182 ret = i2c_master_send(client,tmp,count);
187 static int i2cdev_check(struct device *dev, void *addrp)
189 struct i2c_client *client = i2c_verify_client(dev);
191 if (!client || client->addr != *(unsigned int *)addrp)
194 return dev->driver ? -EBUSY : 0;
197 /* This address checking function differs from the one in i2c-core
198 in that it considers an address with a registered device, but no
199 driver bound to it, as NOT busy. */
200 static int i2cdev_check_addr(struct i2c_adapter *adapter, unsigned int addr)
202 return device_for_each_child(&adapter->dev, &addr, i2cdev_check);
205 static noinline int i2cdev_ioctl_rdrw(struct i2c_client *client,
208 struct i2c_rdwr_ioctl_data rdwr_arg;
209 struct i2c_msg *rdwr_pa;
210 u8 __user **data_ptrs;
213 if (copy_from_user(&rdwr_arg,
214 (struct i2c_rdwr_ioctl_data __user *)arg,
218 /* Put an arbitrary limit on the number of messages that can
220 if (rdwr_arg.nmsgs > I2C_RDRW_IOCTL_MAX_MSGS)
223 rdwr_pa = (struct i2c_msg *)
224 kmalloc(rdwr_arg.nmsgs * sizeof(struct i2c_msg),
229 if (copy_from_user(rdwr_pa, rdwr_arg.msgs,
230 rdwr_arg.nmsgs * sizeof(struct i2c_msg))) {
235 data_ptrs = kmalloc(rdwr_arg.nmsgs * sizeof(u8 __user *), GFP_KERNEL);
236 if (data_ptrs == NULL) {
242 for (i = 0; i < rdwr_arg.nmsgs; i++) {
243 /* Limit the size of the message to a sane amount;
244 * and don't let length change either. */
245 if ((rdwr_pa[i].len > 8192) ||
246 (rdwr_pa[i].flags & I2C_M_RECV_LEN)) {
250 data_ptrs[i] = (u8 __user *)rdwr_pa[i].buf;
251 rdwr_pa[i].buf = kmalloc(rdwr_pa[i].len, GFP_KERNEL);
252 if (rdwr_pa[i].buf == NULL) {
256 if (copy_from_user(rdwr_pa[i].buf, data_ptrs[i],
258 ++i; /* Needs to be kfreed too */
265 for (j = 0; j < i; ++j)
266 kfree(rdwr_pa[j].buf);
272 res = i2c_transfer(client->adapter, rdwr_pa, rdwr_arg.nmsgs);
274 if (res >= 0 && (rdwr_pa[i].flags & I2C_M_RD)) {
275 if (copy_to_user(data_ptrs[i], rdwr_pa[i].buf,
279 kfree(rdwr_pa[i].buf);
286 static noinline int i2cdev_ioctl_smbus(struct i2c_client *client,
289 struct i2c_smbus_ioctl_data data_arg;
290 union i2c_smbus_data temp;
293 if (copy_from_user(&data_arg,
294 (struct i2c_smbus_ioctl_data __user *) arg,
295 sizeof(struct i2c_smbus_ioctl_data)))
297 if ((data_arg.size != I2C_SMBUS_BYTE) &&
298 (data_arg.size != I2C_SMBUS_QUICK) &&
299 (data_arg.size != I2C_SMBUS_BYTE_DATA) &&
300 (data_arg.size != I2C_SMBUS_WORD_DATA) &&
301 (data_arg.size != I2C_SMBUS_PROC_CALL) &&
302 (data_arg.size != I2C_SMBUS_BLOCK_DATA) &&
303 (data_arg.size != I2C_SMBUS_I2C_BLOCK_BROKEN) &&
304 (data_arg.size != I2C_SMBUS_I2C_BLOCK_DATA) &&
305 (data_arg.size != I2C_SMBUS_BLOCK_PROC_CALL)) {
306 dev_dbg(&client->adapter->dev,
307 "size out of range (%x) in ioctl I2C_SMBUS.\n",
311 /* Note that I2C_SMBUS_READ and I2C_SMBUS_WRITE are 0 and 1,
312 so the check is valid if size==I2C_SMBUS_QUICK too. */
313 if ((data_arg.read_write != I2C_SMBUS_READ) &&
314 (data_arg.read_write != I2C_SMBUS_WRITE)) {
315 dev_dbg(&client->adapter->dev,
316 "read_write out of range (%x) in ioctl I2C_SMBUS.\n",
317 data_arg.read_write);
321 /* Note that command values are always valid! */
323 if ((data_arg.size == I2C_SMBUS_QUICK) ||
324 ((data_arg.size == I2C_SMBUS_BYTE) &&
325 (data_arg.read_write == I2C_SMBUS_WRITE)))
326 /* These are special: we do not use data */
327 return i2c_smbus_xfer(client->adapter, client->addr,
328 client->flags, data_arg.read_write,
329 data_arg.command, data_arg.size, NULL);
331 if (data_arg.data == NULL) {
332 dev_dbg(&client->adapter->dev,
333 "data is NULL pointer in ioctl I2C_SMBUS.\n");
337 if ((data_arg.size == I2C_SMBUS_BYTE_DATA) ||
338 (data_arg.size == I2C_SMBUS_BYTE))
339 datasize = sizeof(data_arg.data->byte);
340 else if ((data_arg.size == I2C_SMBUS_WORD_DATA) ||
341 (data_arg.size == I2C_SMBUS_PROC_CALL))
342 datasize = sizeof(data_arg.data->word);
343 else /* size == smbus block, i2c block, or block proc. call */
344 datasize = sizeof(data_arg.data->block);
346 if ((data_arg.size == I2C_SMBUS_PROC_CALL) ||
347 (data_arg.size == I2C_SMBUS_BLOCK_PROC_CALL) ||
348 (data_arg.size == I2C_SMBUS_I2C_BLOCK_DATA) ||
349 (data_arg.read_write == I2C_SMBUS_WRITE)) {
350 if (copy_from_user(&temp, data_arg.data, datasize))
353 if (data_arg.size == I2C_SMBUS_I2C_BLOCK_BROKEN) {
354 /* Convert old I2C block commands to the new
355 convention. This preserves binary compatibility. */
356 data_arg.size = I2C_SMBUS_I2C_BLOCK_DATA;
357 if (data_arg.read_write == I2C_SMBUS_READ)
358 temp.block[0] = I2C_SMBUS_BLOCK_MAX;
360 res = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
361 data_arg.read_write, data_arg.command, data_arg.size, &temp);
362 if (!res && ((data_arg.size == I2C_SMBUS_PROC_CALL) ||
363 (data_arg.size == I2C_SMBUS_BLOCK_PROC_CALL) ||
364 (data_arg.read_write == I2C_SMBUS_READ))) {
365 if (copy_to_user(data_arg.data, &temp, datasize))
371 static long i2cdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
373 struct i2c_client *client = (struct i2c_client *)file->private_data;
376 dev_dbg(&client->adapter->dev, "ioctl, cmd=0x%02x, arg=0x%02lx\n",
381 case I2C_SLAVE_FORCE:
382 /* NOTE: devices set up to work with "new style" drivers
383 * can't use I2C_SLAVE, even when the device node is not
384 * bound to a driver. Only I2C_SLAVE_FORCE will work.
386 * Setting the PEC flag here won't affect kernel drivers,
387 * which will be using the i2c_client node registered with
388 * the driver model core. Likewise, when that client has
389 * the PEC flag already set, the i2c-dev driver won't see
390 * (or use) this setting.
393 (((client->flags & I2C_M_TEN) == 0) && arg > 0x7f))
395 if (cmd == I2C_SLAVE && i2cdev_check_addr(client->adapter, arg))
397 /* REVISIT: address could become busy later */
402 client->flags |= I2C_M_TEN;
404 client->flags &= ~I2C_M_TEN;
408 client->flags |= I2C_CLIENT_PEC;
410 client->flags &= ~I2C_CLIENT_PEC;
413 funcs = i2c_get_functionality(client->adapter);
414 return put_user(funcs, (unsigned long __user *)arg);
417 return i2cdev_ioctl_rdrw(client, arg);
420 return i2cdev_ioctl_smbus(client, arg);
423 client->adapter->retries = arg;
426 /* For historical reasons, user-space sets the timeout
427 * value in units of 10 ms.
429 client->adapter->timeout = msecs_to_jiffies(arg * 10);
432 /* NOTE: returning a fault code here could cause trouble
433 * in buggy userspace code. Some old kernel bugs returned
434 * zero in this case, and userspace code might accidentally
435 * have depended on that bug.
442 static int i2cdev_open(struct inode *inode, struct file *file)
444 unsigned int minor = iminor(inode);
445 struct i2c_client *client;
446 struct i2c_adapter *adap;
447 struct i2c_dev *i2c_dev;
451 i2c_dev = i2c_dev_get_by_minor(minor);
457 adap = i2c_get_adapter(i2c_dev->adap->nr);
463 /* This creates an anonymous i2c_client, which may later be
464 * pointed to some address using I2C_SLAVE or I2C_SLAVE_FORCE.
466 * This client is ** NEVER REGISTERED ** with the driver model
467 * or I2C core code!! It just holds private copies of addressing
468 * information and maybe a PEC flag.
470 client = kzalloc(sizeof(*client), GFP_KERNEL);
472 i2c_put_adapter(adap);
476 snprintf(client->name, I2C_NAME_SIZE, "i2c-dev %d", adap->nr);
477 client->driver = &i2cdev_driver;
479 client->adapter = adap;
480 file->private_data = client;
487 static int i2cdev_release(struct inode *inode, struct file *file)
489 struct i2c_client *client = file->private_data;
491 i2c_put_adapter(client->adapter);
493 file->private_data = NULL;
498 static const struct file_operations i2cdev_fops = {
499 .owner = THIS_MODULE,
502 .write = i2cdev_write,
503 .unlocked_ioctl = i2cdev_ioctl,
505 .release = i2cdev_release,
508 /* ------------------------------------------------------------------------- */
511 * The legacy "i2cdev_driver" is used primarily to get notifications when
512 * I2C adapters are added or removed, so that each one gets an i2c_dev
513 * and is thus made available to userspace driver code.
516 static struct class *i2c_dev_class;
518 static int i2cdev_attach_adapter(struct i2c_adapter *adap)
520 struct i2c_dev *i2c_dev;
523 i2c_dev = get_free_i2c_dev(adap);
525 return PTR_ERR(i2c_dev);
527 /* register this i2c device with the driver core */
528 i2c_dev->dev = device_create(i2c_dev_class, &adap->dev,
529 MKDEV(I2C_MAJOR, adap->nr), NULL,
531 if (IS_ERR(i2c_dev->dev)) {
532 res = PTR_ERR(i2c_dev->dev);
535 res = device_create_file(i2c_dev->dev, &dev_attr_name);
539 pr_debug("i2c-dev: adapter [%s] registered as minor %d\n",
540 adap->name, adap->nr);
543 device_destroy(i2c_dev_class, MKDEV(I2C_MAJOR, adap->nr));
545 return_i2c_dev(i2c_dev);
549 static int i2cdev_detach_adapter(struct i2c_adapter *adap)
551 struct i2c_dev *i2c_dev;
553 i2c_dev = i2c_dev_get_by_minor(adap->nr);
554 if (!i2c_dev) /* attach_adapter must have failed */
557 device_remove_file(i2c_dev->dev, &dev_attr_name);
558 return_i2c_dev(i2c_dev);
559 device_destroy(i2c_dev_class, MKDEV(I2C_MAJOR, adap->nr));
561 pr_debug("i2c-dev: adapter [%s] unregistered\n", adap->name);
565 static struct i2c_driver i2cdev_driver = {
567 .name = "dev_driver",
569 .attach_adapter = i2cdev_attach_adapter,
570 .detach_adapter = i2cdev_detach_adapter,
573 /* ------------------------------------------------------------------------- */
576 * module load/unload record keeping
579 static int __init i2c_dev_init(void)
583 printk(KERN_INFO "i2c /dev entries driver\n");
585 res = register_chrdev(I2C_MAJOR, "i2c", &i2cdev_fops);
589 i2c_dev_class = class_create(THIS_MODULE, "i2c-dev");
590 if (IS_ERR(i2c_dev_class)) {
591 res = PTR_ERR(i2c_dev_class);
592 goto out_unreg_chrdev;
595 res = i2c_add_driver(&i2cdev_driver);
597 goto out_unreg_class;
602 class_destroy(i2c_dev_class);
604 unregister_chrdev(I2C_MAJOR, "i2c");
606 printk(KERN_ERR "%s: Driver Initialisation failed\n", __FILE__);
610 static void __exit i2c_dev_exit(void)
612 i2c_del_driver(&i2cdev_driver);
613 class_destroy(i2c_dev_class);
614 unregister_chrdev(I2C_MAJOR,"i2c");
617 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and "
618 "Simon G. Vogl <simon@tk.uni-linz.ac.at>");
619 MODULE_DESCRIPTION("I2C /dev entries driver");
620 MODULE_LICENSE("GPL");
622 module_init(i2c_dev_init);
623 module_exit(i2c_dev_exit);