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., 51 Franklin Street, Fifth Floor, Boston,
24 /* Note that this is a complete rewrite of Simon Vogl's i2c-dev module.
25 But I have used so much of his original code and ideas that it seems
26 only fair to recognize him as co-author -- Frodo */
28 /* The I2C_RDWR ioctl code is written by Kolja Waschk <waschk@telos.de> */
30 #include <linux/kernel.h>
31 #include <linux/module.h>
32 #include <linux/device.h>
33 #include <linux/notifier.h>
35 #include <linux/slab.h>
36 #include <linux/init.h>
37 #include <linux/list.h>
38 #include <linux/i2c.h>
39 #include <linux/i2c-dev.h>
40 #include <linux/jiffies.h>
41 #include <linux/uaccess.h>
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 bus notifications.
52 struct list_head list;
53 struct i2c_adapter *adap;
57 #define I2C_MINORS 256
58 static LIST_HEAD(i2c_dev_list);
59 static DEFINE_SPINLOCK(i2c_dev_list_lock);
61 static struct i2c_dev *i2c_dev_get_by_minor(unsigned index)
63 struct i2c_dev *i2c_dev;
65 spin_lock(&i2c_dev_list_lock);
66 list_for_each_entry(i2c_dev, &i2c_dev_list, list) {
67 if (i2c_dev->adap->nr == index)
72 spin_unlock(&i2c_dev_list_lock);
76 static struct i2c_dev *get_free_i2c_dev(struct i2c_adapter *adap)
78 struct i2c_dev *i2c_dev;
80 if (adap->nr >= I2C_MINORS) {
81 printk(KERN_ERR "i2c-dev: Out of device minors (%d)\n",
83 return ERR_PTR(-ENODEV);
86 i2c_dev = kzalloc(sizeof(*i2c_dev), GFP_KERNEL);
88 return ERR_PTR(-ENOMEM);
91 spin_lock(&i2c_dev_list_lock);
92 list_add_tail(&i2c_dev->list, &i2c_dev_list);
93 spin_unlock(&i2c_dev_list_lock);
97 static void return_i2c_dev(struct i2c_dev *i2c_dev)
99 spin_lock(&i2c_dev_list_lock);
100 list_del(&i2c_dev->list);
101 spin_unlock(&i2c_dev_list_lock);
105 static ssize_t show_adapter_name(struct device *dev,
106 struct device_attribute *attr, char *buf)
108 struct i2c_dev *i2c_dev = i2c_dev_get_by_minor(MINOR(dev->devt));
112 return sprintf(buf, "%s\n", i2c_dev->adap->name);
114 static DEVICE_ATTR(name, S_IRUGO, show_adapter_name, NULL);
116 /* ------------------------------------------------------------------------- */
119 * After opening an instance of this character special file, a file
120 * descriptor starts out associated only with an i2c_adapter (and bus).
122 * Using the I2C_RDWR ioctl(), you can then *immediately* issue i2c_msg
123 * traffic to any devices on the bus used by that adapter. That's because
124 * the i2c_msg vectors embed all the addressing information they need, and
125 * are submitted directly to an i2c_adapter. However, SMBus-only adapters
126 * don't support that interface.
128 * To use read()/write() system calls on that file descriptor, or to use
129 * SMBus interfaces (and work with SMBus-only hosts!), you must first issue
130 * an I2C_SLAVE (or I2C_SLAVE_FORCE) ioctl. That configures an anonymous
131 * (never registered) i2c_client so it holds the addressing information
132 * needed by those system calls and by this SMBus interface.
135 static ssize_t i2cdev_read(struct file *file, char __user *buf, size_t count,
141 struct i2c_client *client = file->private_data;
146 tmp = kmalloc(count, GFP_KERNEL);
150 pr_debug("i2c-dev: i2c-%d reading %zu bytes.\n",
151 iminor(file->f_path.dentry->d_inode), count);
153 ret = i2c_master_recv(client, tmp, count);
155 ret = copy_to_user(buf, tmp, count) ? -EFAULT : ret;
160 static ssize_t i2cdev_write(struct file *file, const char __user *buf,
161 size_t count, loff_t *offset)
165 struct i2c_client *client = file->private_data;
170 tmp = memdup_user(buf, count);
174 pr_debug("i2c-dev: i2c-%d writing %zu bytes.\n",
175 iminor(file->f_path.dentry->d_inode), count);
177 ret = i2c_master_send(client, tmp, count);
182 static int i2cdev_check(struct device *dev, void *addrp)
184 struct i2c_client *client = i2c_verify_client(dev);
186 if (!client || client->addr != *(unsigned int *)addrp)
189 return dev->driver ? -EBUSY : 0;
192 /* walk up mux tree */
193 static int i2cdev_check_mux_parents(struct i2c_adapter *adapter, int addr)
195 struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
198 result = device_for_each_child(&adapter->dev, &addr, i2cdev_check);
199 if (!result && parent)
200 result = i2cdev_check_mux_parents(parent, addr);
205 /* recurse down mux tree */
206 static int i2cdev_check_mux_children(struct device *dev, void *addrp)
210 if (dev->type == &i2c_adapter_type)
211 result = device_for_each_child(dev, addrp,
212 i2cdev_check_mux_children);
214 result = i2cdev_check(dev, addrp);
219 /* This address checking function differs from the one in i2c-core
220 in that it considers an address with a registered device, but no
221 driver bound to it, as NOT busy. */
222 static int i2cdev_check_addr(struct i2c_adapter *adapter, unsigned int addr)
224 struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
228 result = i2cdev_check_mux_parents(parent, addr);
231 result = device_for_each_child(&adapter->dev, &addr,
232 i2cdev_check_mux_children);
237 static noinline int i2cdev_ioctl_rdrw(struct i2c_client *client,
240 struct i2c_rdwr_ioctl_data rdwr_arg;
241 struct i2c_msg *rdwr_pa;
242 u8 __user **data_ptrs;
245 if (copy_from_user(&rdwr_arg,
246 (struct i2c_rdwr_ioctl_data __user *)arg,
250 /* Put an arbitrary limit on the number of messages that can
252 if (rdwr_arg.nmsgs > I2C_RDRW_IOCTL_MAX_MSGS)
255 rdwr_pa = memdup_user(rdwr_arg.msgs,
256 rdwr_arg.nmsgs * sizeof(struct i2c_msg));
258 return PTR_ERR(rdwr_pa);
260 data_ptrs = kmalloc(rdwr_arg.nmsgs * sizeof(u8 __user *), GFP_KERNEL);
261 if (data_ptrs == NULL) {
267 for (i = 0; i < rdwr_arg.nmsgs; i++) {
268 /* Limit the size of the message to a sane amount;
269 * and don't let length change either. */
270 if ((rdwr_pa[i].len > 8192) ||
271 (rdwr_pa[i].flags & I2C_M_RECV_LEN)) {
275 data_ptrs[i] = (u8 __user *)rdwr_pa[i].buf;
276 rdwr_pa[i].buf = memdup_user(data_ptrs[i], rdwr_pa[i].len);
277 if (IS_ERR(rdwr_pa[i].buf)) {
278 res = PTR_ERR(rdwr_pa[i].buf);
284 for (j = 0; j < i; ++j)
285 kfree(rdwr_pa[j].buf);
291 res = i2c_transfer(client->adapter, rdwr_pa, rdwr_arg.nmsgs);
293 if (res >= 0 && (rdwr_pa[i].flags & I2C_M_RD)) {
294 if (copy_to_user(data_ptrs[i], rdwr_pa[i].buf,
298 kfree(rdwr_pa[i].buf);
305 static noinline int i2cdev_ioctl_smbus(struct i2c_client *client,
308 struct i2c_smbus_ioctl_data data_arg;
309 union i2c_smbus_data temp;
312 if (copy_from_user(&data_arg,
313 (struct i2c_smbus_ioctl_data __user *) arg,
314 sizeof(struct i2c_smbus_ioctl_data)))
316 if ((data_arg.size != I2C_SMBUS_BYTE) &&
317 (data_arg.size != I2C_SMBUS_QUICK) &&
318 (data_arg.size != I2C_SMBUS_BYTE_DATA) &&
319 (data_arg.size != I2C_SMBUS_WORD_DATA) &&
320 (data_arg.size != I2C_SMBUS_PROC_CALL) &&
321 (data_arg.size != I2C_SMBUS_BLOCK_DATA) &&
322 (data_arg.size != I2C_SMBUS_I2C_BLOCK_BROKEN) &&
323 (data_arg.size != I2C_SMBUS_I2C_BLOCK_DATA) &&
324 (data_arg.size != I2C_SMBUS_BLOCK_PROC_CALL)) {
325 dev_dbg(&client->adapter->dev,
326 "size out of range (%x) in ioctl I2C_SMBUS.\n",
330 /* Note that I2C_SMBUS_READ and I2C_SMBUS_WRITE are 0 and 1,
331 so the check is valid if size==I2C_SMBUS_QUICK too. */
332 if ((data_arg.read_write != I2C_SMBUS_READ) &&
333 (data_arg.read_write != I2C_SMBUS_WRITE)) {
334 dev_dbg(&client->adapter->dev,
335 "read_write out of range (%x) in ioctl I2C_SMBUS.\n",
336 data_arg.read_write);
340 /* Note that command values are always valid! */
342 if ((data_arg.size == I2C_SMBUS_QUICK) ||
343 ((data_arg.size == I2C_SMBUS_BYTE) &&
344 (data_arg.read_write == I2C_SMBUS_WRITE)))
345 /* These are special: we do not use data */
346 return i2c_smbus_xfer(client->adapter, client->addr,
347 client->flags, data_arg.read_write,
348 data_arg.command, data_arg.size, NULL);
350 if (data_arg.data == NULL) {
351 dev_dbg(&client->adapter->dev,
352 "data is NULL pointer in ioctl I2C_SMBUS.\n");
356 if ((data_arg.size == I2C_SMBUS_BYTE_DATA) ||
357 (data_arg.size == I2C_SMBUS_BYTE))
358 datasize = sizeof(data_arg.data->byte);
359 else if ((data_arg.size == I2C_SMBUS_WORD_DATA) ||
360 (data_arg.size == I2C_SMBUS_PROC_CALL))
361 datasize = sizeof(data_arg.data->word);
362 else /* size == smbus block, i2c block, or block proc. call */
363 datasize = sizeof(data_arg.data->block);
365 if ((data_arg.size == I2C_SMBUS_PROC_CALL) ||
366 (data_arg.size == I2C_SMBUS_BLOCK_PROC_CALL) ||
367 (data_arg.size == I2C_SMBUS_I2C_BLOCK_DATA) ||
368 (data_arg.read_write == I2C_SMBUS_WRITE)) {
369 if (copy_from_user(&temp, data_arg.data, datasize))
372 if (data_arg.size == I2C_SMBUS_I2C_BLOCK_BROKEN) {
373 /* Convert old I2C block commands to the new
374 convention. This preserves binary compatibility. */
375 data_arg.size = I2C_SMBUS_I2C_BLOCK_DATA;
376 if (data_arg.read_write == I2C_SMBUS_READ)
377 temp.block[0] = I2C_SMBUS_BLOCK_MAX;
379 res = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
380 data_arg.read_write, data_arg.command, data_arg.size, &temp);
381 if (!res && ((data_arg.size == I2C_SMBUS_PROC_CALL) ||
382 (data_arg.size == I2C_SMBUS_BLOCK_PROC_CALL) ||
383 (data_arg.read_write == I2C_SMBUS_READ))) {
384 if (copy_to_user(data_arg.data, &temp, datasize))
390 static long i2cdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
392 struct i2c_client *client = file->private_data;
395 dev_dbg(&client->adapter->dev, "ioctl, cmd=0x%02x, arg=0x%02lx\n",
400 case I2C_SLAVE_FORCE:
401 /* NOTE: devices set up to work with "new style" drivers
402 * can't use I2C_SLAVE, even when the device node is not
403 * bound to a driver. Only I2C_SLAVE_FORCE will work.
405 * Setting the PEC flag here won't affect kernel drivers,
406 * which will be using the i2c_client node registered with
407 * the driver model core. Likewise, when that client has
408 * the PEC flag already set, the i2c-dev driver won't see
409 * (or use) this setting.
412 (((client->flags & I2C_M_TEN) == 0) && arg > 0x7f))
414 if (cmd == I2C_SLAVE && i2cdev_check_addr(client->adapter, arg))
416 /* REVISIT: address could become busy later */
421 client->flags |= I2C_M_TEN;
423 client->flags &= ~I2C_M_TEN;
427 client->flags |= I2C_CLIENT_PEC;
429 client->flags &= ~I2C_CLIENT_PEC;
432 funcs = i2c_get_functionality(client->adapter);
433 return put_user(funcs, (unsigned long __user *)arg);
436 return i2cdev_ioctl_rdrw(client, arg);
439 return i2cdev_ioctl_smbus(client, arg);
442 client->adapter->retries = arg;
445 /* For historical reasons, user-space sets the timeout
446 * value in units of 10 ms.
448 client->adapter->timeout = msecs_to_jiffies(arg * 10);
451 /* NOTE: returning a fault code here could cause trouble
452 * in buggy userspace code. Some old kernel bugs returned
453 * zero in this case, and userspace code might accidentally
454 * have depended on that bug.
461 static int i2cdev_open(struct inode *inode, struct file *file)
463 unsigned int minor = iminor(inode);
464 struct i2c_client *client;
465 struct i2c_adapter *adap;
466 struct i2c_dev *i2c_dev;
468 i2c_dev = i2c_dev_get_by_minor(minor);
472 adap = i2c_get_adapter(i2c_dev->adap->nr);
476 /* This creates an anonymous i2c_client, which may later be
477 * pointed to some address using I2C_SLAVE or I2C_SLAVE_FORCE.
479 * This client is ** NEVER REGISTERED ** with the driver model
480 * or I2C core code!! It just holds private copies of addressing
481 * information and maybe a PEC flag.
483 client = kzalloc(sizeof(*client), GFP_KERNEL);
485 i2c_put_adapter(adap);
488 snprintf(client->name, I2C_NAME_SIZE, "i2c-dev %d", adap->nr);
490 client->adapter = adap;
491 file->private_data = client;
496 static int i2cdev_release(struct inode *inode, struct file *file)
498 struct i2c_client *client = file->private_data;
500 i2c_put_adapter(client->adapter);
502 file->private_data = NULL;
507 static const struct file_operations i2cdev_fops = {
508 .owner = THIS_MODULE,
511 .write = i2cdev_write,
512 .unlocked_ioctl = i2cdev_ioctl,
514 .release = i2cdev_release,
517 /* ------------------------------------------------------------------------- */
519 static struct class *i2c_dev_class;
521 static int i2cdev_attach_adapter(struct device *dev, void *dummy)
523 struct i2c_adapter *adap;
524 struct i2c_dev *i2c_dev;
527 if (dev->type != &i2c_adapter_type)
529 adap = to_i2c_adapter(dev);
531 i2c_dev = get_free_i2c_dev(adap);
533 return PTR_ERR(i2c_dev);
535 /* register this i2c device with the driver core */
536 i2c_dev->dev = device_create(i2c_dev_class, &adap->dev,
537 MKDEV(I2C_MAJOR, adap->nr), NULL,
539 if (IS_ERR(i2c_dev->dev)) {
540 res = PTR_ERR(i2c_dev->dev);
543 res = device_create_file(i2c_dev->dev, &dev_attr_name);
547 pr_debug("i2c-dev: adapter [%s] registered as minor %d\n",
548 adap->name, adap->nr);
551 device_destroy(i2c_dev_class, MKDEV(I2C_MAJOR, adap->nr));
553 return_i2c_dev(i2c_dev);
557 static int i2cdev_detach_adapter(struct device *dev, void *dummy)
559 struct i2c_adapter *adap;
560 struct i2c_dev *i2c_dev;
562 if (dev->type != &i2c_adapter_type)
564 adap = to_i2c_adapter(dev);
566 i2c_dev = i2c_dev_get_by_minor(adap->nr);
567 if (!i2c_dev) /* attach_adapter must have failed */
570 device_remove_file(i2c_dev->dev, &dev_attr_name);
571 return_i2c_dev(i2c_dev);
572 device_destroy(i2c_dev_class, MKDEV(I2C_MAJOR, adap->nr));
574 pr_debug("i2c-dev: adapter [%s] unregistered\n", adap->name);
578 static int i2cdev_notifier_call(struct notifier_block *nb, unsigned long action,
581 struct device *dev = data;
584 case BUS_NOTIFY_ADD_DEVICE:
585 return i2cdev_attach_adapter(dev, NULL);
586 case BUS_NOTIFY_DEL_DEVICE:
587 return i2cdev_detach_adapter(dev, NULL);
593 static struct notifier_block i2cdev_notifier = {
594 .notifier_call = i2cdev_notifier_call,
597 /* ------------------------------------------------------------------------- */
600 * module load/unload record keeping
603 static int __init i2c_dev_init(void)
607 printk(KERN_INFO "i2c /dev entries driver\n");
609 res = register_chrdev(I2C_MAJOR, "i2c", &i2cdev_fops);
613 i2c_dev_class = class_create(THIS_MODULE, "i2c-dev");
614 if (IS_ERR(i2c_dev_class)) {
615 res = PTR_ERR(i2c_dev_class);
616 goto out_unreg_chrdev;
619 /* Keep track of adapters which will be added or removed later */
620 res = bus_register_notifier(&i2c_bus_type, &i2cdev_notifier);
622 goto out_unreg_class;
624 /* Bind to already existing adapters right away */
625 i2c_for_each_dev(NULL, i2cdev_attach_adapter);
630 class_destroy(i2c_dev_class);
632 unregister_chrdev(I2C_MAJOR, "i2c");
634 printk(KERN_ERR "%s: Driver Initialisation failed\n", __FILE__);
638 static void __exit i2c_dev_exit(void)
640 bus_unregister_notifier(&i2c_bus_type, &i2cdev_notifier);
641 i2c_for_each_dev(NULL, i2cdev_detach_adapter);
642 class_destroy(i2c_dev_class);
643 unregister_chrdev(I2C_MAJOR, "i2c");
646 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and "
647 "Simon G. Vogl <simon@tk.uni-linz.ac.at>");
648 MODULE_DESCRIPTION("I2C /dev entries driver");
649 MODULE_LICENSE("GPL");
651 module_init(i2c_dev_init);
652 module_exit(i2c_dev_exit);