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 <asm/uaccess.h>
39 static struct i2c_driver i2cdev_driver;
42 * An i2c_dev represents an i2c_adapter ... an I2C or SMBus master, not a
43 * slave (i2c_client) with which messages will be exchanged. It's coupled
44 * with a character special file which is accessed by user mode drivers.
46 * The list of i2c_dev structures is parallel to the i2c_adapter lists
47 * maintained by the driver model, and is updated using notifications
48 * delivered to the i2cdev_driver.
51 struct list_head list;
52 struct i2c_adapter *adap;
56 #define I2C_MINORS 256
57 static LIST_HEAD(i2c_dev_list);
58 static DEFINE_SPINLOCK(i2c_dev_list_lock);
60 static struct i2c_dev *i2c_dev_get_by_minor(unsigned index)
62 struct i2c_dev *i2c_dev;
64 spin_lock(&i2c_dev_list_lock);
65 list_for_each_entry(i2c_dev, &i2c_dev_list, list) {
66 if (i2c_dev->adap->nr == index)
71 spin_unlock(&i2c_dev_list_lock);
75 static struct i2c_dev *get_free_i2c_dev(struct i2c_adapter *adap)
77 struct i2c_dev *i2c_dev;
79 if (adap->nr >= I2C_MINORS) {
80 printk(KERN_ERR "i2c-dev: Out of device minors (%d)\n",
82 return ERR_PTR(-ENODEV);
85 i2c_dev = kzalloc(sizeof(*i2c_dev), GFP_KERNEL);
87 return ERR_PTR(-ENOMEM);
90 spin_lock(&i2c_dev_list_lock);
91 list_add_tail(&i2c_dev->list, &i2c_dev_list);
92 spin_unlock(&i2c_dev_list_lock);
96 static void return_i2c_dev(struct i2c_dev *i2c_dev)
98 spin_lock(&i2c_dev_list_lock);
99 list_del(&i2c_dev->list);
100 spin_unlock(&i2c_dev_list_lock);
104 static ssize_t show_adapter_name(struct device *dev,
105 struct device_attribute *attr, char *buf)
107 struct i2c_dev *i2c_dev = i2c_dev_get_by_minor(MINOR(dev->devt));
111 return sprintf(buf, "%s\n", i2c_dev->adap->name);
113 static DEVICE_ATTR(name, S_IRUGO, show_adapter_name, NULL);
115 /* ------------------------------------------------------------------------- */
118 * After opening an instance of this character special file, a file
119 * descriptor starts out associated only with an i2c_adapter (and bus).
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.
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.
134 static ssize_t i2cdev_read (struct file *file, char __user *buf, size_t count,
140 struct i2c_client *client = (struct i2c_client *)file->private_data;
145 tmp = kmalloc(count,GFP_KERNEL);
149 pr_debug("i2c-dev: i2c-%d reading %zd bytes.\n",
150 iminor(file->f_path.dentry->d_inode), count);
152 ret = i2c_master_recv(client,tmp,count);
154 ret = copy_to_user(buf,tmp,count)?-EFAULT:ret;
159 static ssize_t i2cdev_write (struct file *file, const char __user *buf, size_t count,
164 struct i2c_client *client = (struct i2c_client *)file->private_data;
169 tmp = kmalloc(count,GFP_KERNEL);
172 if (copy_from_user(tmp,buf,count)) {
177 pr_debug("i2c-dev: i2c-%d writing %zd bytes.\n",
178 iminor(file->f_path.dentry->d_inode), count);
180 ret = i2c_master_send(client,tmp,count);
185 static int i2cdev_ioctl(struct inode *inode, struct file *file,
186 unsigned int cmd, unsigned long arg)
188 struct i2c_client *client = (struct i2c_client *)file->private_data;
189 struct i2c_rdwr_ioctl_data rdwr_arg;
190 struct i2c_smbus_ioctl_data data_arg;
191 union i2c_smbus_data temp;
192 struct i2c_msg *rdwr_pa;
193 u8 __user **data_ptrs;
197 dev_dbg(&client->adapter->dev, "ioctl, cmd=0x%02x, arg=0x%02lx\n",
202 case I2C_SLAVE_FORCE:
203 /* NOTE: devices set up to work with "new style" drivers
204 * can't use I2C_SLAVE, even when the device node is not
205 * bound to a driver. Only I2C_SLAVE_FORCE will work.
207 * Setting the PEC flag here won't affect kernel drivers,
208 * which will be using the i2c_client node registered with
209 * the driver model core. Likewise, when that client has
210 * the PEC flag already set, the i2c-dev driver won't see
211 * (or use) this setting.
214 (((client->flags & I2C_M_TEN) == 0) && arg > 0x7f))
216 if ((cmd == I2C_SLAVE) && i2c_check_addr(client->adapter,arg))
222 client->flags |= I2C_M_TEN;
224 client->flags &= ~I2C_M_TEN;
228 client->flags |= I2C_CLIENT_PEC;
230 client->flags &= ~I2C_CLIENT_PEC;
233 funcs = i2c_get_functionality(client->adapter);
234 return put_user(funcs, (unsigned long __user *)arg);
237 if (copy_from_user(&rdwr_arg,
238 (struct i2c_rdwr_ioctl_data __user *)arg,
242 /* Put an arbitrary limit on the number of messages that can
244 if (rdwr_arg.nmsgs > I2C_RDRW_IOCTL_MAX_MSGS)
247 rdwr_pa = (struct i2c_msg *)
248 kmalloc(rdwr_arg.nmsgs * sizeof(struct i2c_msg),
251 if (rdwr_pa == NULL) return -ENOMEM;
253 if (copy_from_user(rdwr_pa, rdwr_arg.msgs,
254 rdwr_arg.nmsgs * sizeof(struct i2c_msg))) {
259 data_ptrs = kmalloc(rdwr_arg.nmsgs * sizeof(u8 __user *), GFP_KERNEL);
260 if (data_ptrs == NULL) {
266 for( i=0; i<rdwr_arg.nmsgs; i++ ) {
267 /* Limit the size of the message to a sane amount;
268 * and don't let length change either. */
269 if ((rdwr_pa[i].len > 8192) ||
270 (rdwr_pa[i].flags & I2C_M_RECV_LEN)) {
274 data_ptrs[i] = (u8 __user *)rdwr_pa[i].buf;
275 rdwr_pa[i].buf = kmalloc(rdwr_pa[i].len, GFP_KERNEL);
276 if(rdwr_pa[i].buf == NULL) {
280 if(copy_from_user(rdwr_pa[i].buf,
283 ++i; /* Needs to be kfreed too */
290 for (j = 0; j < i; ++j)
291 kfree(rdwr_pa[j].buf);
297 res = i2c_transfer(client->adapter,
301 if( res>=0 && (rdwr_pa[i].flags & I2C_M_RD)) {
309 kfree(rdwr_pa[i].buf);
316 if (copy_from_user(&data_arg,
317 (struct i2c_smbus_ioctl_data __user *) arg,
318 sizeof(struct i2c_smbus_ioctl_data)))
320 if ((data_arg.size != I2C_SMBUS_BYTE) &&
321 (data_arg.size != I2C_SMBUS_QUICK) &&
322 (data_arg.size != I2C_SMBUS_BYTE_DATA) &&
323 (data_arg.size != I2C_SMBUS_WORD_DATA) &&
324 (data_arg.size != I2C_SMBUS_PROC_CALL) &&
325 (data_arg.size != I2C_SMBUS_BLOCK_DATA) &&
326 (data_arg.size != I2C_SMBUS_I2C_BLOCK_BROKEN) &&
327 (data_arg.size != I2C_SMBUS_I2C_BLOCK_DATA) &&
328 (data_arg.size != I2C_SMBUS_BLOCK_PROC_CALL)) {
329 dev_dbg(&client->adapter->dev,
330 "size out of range (%x) in ioctl I2C_SMBUS.\n",
334 /* Note that I2C_SMBUS_READ and I2C_SMBUS_WRITE are 0 and 1,
335 so the check is valid if size==I2C_SMBUS_QUICK too. */
336 if ((data_arg.read_write != I2C_SMBUS_READ) &&
337 (data_arg.read_write != I2C_SMBUS_WRITE)) {
338 dev_dbg(&client->adapter->dev,
339 "read_write out of range (%x) in ioctl I2C_SMBUS.\n",
340 data_arg.read_write);
344 /* Note that command values are always valid! */
346 if ((data_arg.size == I2C_SMBUS_QUICK) ||
347 ((data_arg.size == I2C_SMBUS_BYTE) &&
348 (data_arg.read_write == I2C_SMBUS_WRITE)))
349 /* These are special: we do not use data */
350 return i2c_smbus_xfer(client->adapter, client->addr,
354 data_arg.size, NULL);
356 if (data_arg.data == NULL) {
357 dev_dbg(&client->adapter->dev,
358 "data is NULL pointer in ioctl I2C_SMBUS.\n");
362 if ((data_arg.size == I2C_SMBUS_BYTE_DATA) ||
363 (data_arg.size == I2C_SMBUS_BYTE))
364 datasize = sizeof(data_arg.data->byte);
365 else if ((data_arg.size == I2C_SMBUS_WORD_DATA) ||
366 (data_arg.size == I2C_SMBUS_PROC_CALL))
367 datasize = sizeof(data_arg.data->word);
368 else /* size == smbus block, i2c block, or block proc. call */
369 datasize = sizeof(data_arg.data->block);
371 if ((data_arg.size == I2C_SMBUS_PROC_CALL) ||
372 (data_arg.size == I2C_SMBUS_BLOCK_PROC_CALL) ||
373 (data_arg.size == I2C_SMBUS_I2C_BLOCK_DATA) ||
374 (data_arg.read_write == I2C_SMBUS_WRITE)) {
375 if (copy_from_user(&temp, data_arg.data, datasize))
378 if (data_arg.size == I2C_SMBUS_I2C_BLOCK_BROKEN) {
379 /* Convert old I2C block commands to the new
380 convention. This preserves binary compatibility. */
381 data_arg.size = I2C_SMBUS_I2C_BLOCK_DATA;
382 if (data_arg.read_write == I2C_SMBUS_READ)
383 temp.block[0] = I2C_SMBUS_BLOCK_MAX;
385 res = i2c_smbus_xfer(client->adapter,client->addr,client->flags,
387 data_arg.command,data_arg.size,&temp);
388 if (! res && ((data_arg.size == I2C_SMBUS_PROC_CALL) ||
389 (data_arg.size == I2C_SMBUS_BLOCK_PROC_CALL) ||
390 (data_arg.read_write == I2C_SMBUS_READ))) {
391 if (copy_to_user(data_arg.data, &temp, datasize))
396 client->adapter->retries = arg;
399 client->adapter->timeout = arg;
402 /* NOTE: returning a fault code here could cause trouble
403 * in buggy userspace code. Some old kernel bugs returned
404 * zero in this case, and userspace code might accidentally
405 * have depended on that bug.
412 static int i2cdev_open(struct inode *inode, struct file *file)
414 unsigned int minor = iminor(inode);
415 struct i2c_client *client;
416 struct i2c_adapter *adap;
417 struct i2c_dev *i2c_dev;
419 i2c_dev = i2c_dev_get_by_minor(minor);
423 adap = i2c_get_adapter(i2c_dev->adap->nr);
427 /* This creates an anonymous i2c_client, which may later be
428 * pointed to some address using I2C_SLAVE or I2C_SLAVE_FORCE.
430 * This client is ** NEVER REGISTERED ** with the driver model
431 * or I2C core code!! It just holds private copies of addressing
432 * information and maybe a PEC flag.
434 client = kzalloc(sizeof(*client), GFP_KERNEL);
436 i2c_put_adapter(adap);
439 snprintf(client->name, I2C_NAME_SIZE, "i2c-dev %d", adap->nr);
440 client->driver = &i2cdev_driver;
442 client->adapter = adap;
443 file->private_data = client;
448 static int i2cdev_release(struct inode *inode, struct file *file)
450 struct i2c_client *client = file->private_data;
452 i2c_put_adapter(client->adapter);
454 file->private_data = NULL;
459 static const struct file_operations i2cdev_fops = {
460 .owner = THIS_MODULE,
463 .write = i2cdev_write,
464 .ioctl = i2cdev_ioctl,
466 .release = i2cdev_release,
469 /* ------------------------------------------------------------------------- */
472 * The legacy "i2cdev_driver" is used primarily to get notifications when
473 * I2C adapters are added or removed, so that each one gets an i2c_dev
474 * and is thus made available to userspace driver code.
477 static struct class *i2c_dev_class;
479 static int i2cdev_attach_adapter(struct i2c_adapter *adap)
481 struct i2c_dev *i2c_dev;
484 i2c_dev = get_free_i2c_dev(adap);
486 return PTR_ERR(i2c_dev);
488 /* register this i2c device with the driver core */
489 i2c_dev->dev = device_create(i2c_dev_class, &adap->dev,
490 MKDEV(I2C_MAJOR, adap->nr),
492 if (IS_ERR(i2c_dev->dev)) {
493 res = PTR_ERR(i2c_dev->dev);
496 res = device_create_file(i2c_dev->dev, &dev_attr_name);
500 pr_debug("i2c-dev: adapter [%s] registered as minor %d\n",
501 adap->name, adap->nr);
504 device_destroy(i2c_dev_class, MKDEV(I2C_MAJOR, adap->nr));
506 return_i2c_dev(i2c_dev);
510 static int i2cdev_detach_adapter(struct i2c_adapter *adap)
512 struct i2c_dev *i2c_dev;
514 i2c_dev = i2c_dev_get_by_minor(adap->nr);
515 if (!i2c_dev) /* attach_adapter must have failed */
518 device_remove_file(i2c_dev->dev, &dev_attr_name);
519 return_i2c_dev(i2c_dev);
520 device_destroy(i2c_dev_class, MKDEV(I2C_MAJOR, adap->nr));
522 pr_debug("i2c-dev: adapter [%s] unregistered\n", adap->name);
526 static int i2cdev_detach_client(struct i2c_client *client)
531 static struct i2c_driver i2cdev_driver = {
533 .name = "dev_driver",
535 .id = I2C_DRIVERID_I2CDEV,
536 .attach_adapter = i2cdev_attach_adapter,
537 .detach_adapter = i2cdev_detach_adapter,
538 .detach_client = i2cdev_detach_client,
541 /* ------------------------------------------------------------------------- */
544 * module load/unload record keeping
547 static int __init i2c_dev_init(void)
551 printk(KERN_INFO "i2c /dev entries driver\n");
553 res = register_chrdev(I2C_MAJOR, "i2c", &i2cdev_fops);
557 i2c_dev_class = class_create(THIS_MODULE, "i2c-dev");
558 if (IS_ERR(i2c_dev_class))
559 goto out_unreg_chrdev;
561 res = i2c_add_driver(&i2cdev_driver);
563 goto out_unreg_class;
568 class_destroy(i2c_dev_class);
570 unregister_chrdev(I2C_MAJOR, "i2c");
572 printk(KERN_ERR "%s: Driver Initialisation failed\n", __FILE__);
576 static void __exit i2c_dev_exit(void)
578 i2c_del_driver(&i2cdev_driver);
579 class_destroy(i2c_dev_class);
580 unregister_chrdev(I2C_MAJOR,"i2c");
583 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and "
584 "Simon G. Vogl <simon@tk.uni-linz.ac.at>");
585 MODULE_DESCRIPTION("I2C /dev entries driver");
586 MODULE_LICENSE("GPL");
588 module_init(i2c_dev_init);
589 module_exit(i2c_dev_exit);