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.
19 /* Note that this is a complete rewrite of Simon Vogl's i2c-dev module.
20 But I have used so much of his original code and ideas that it seems
21 only fair to recognize him as co-author -- Frodo */
23 /* The I2C_RDWR ioctl code is written by Kolja Waschk <waschk@telos.de> */
25 #include <linux/cdev.h>
26 #include <linux/device.h>
28 #include <linux/i2c-dev.h>
29 #include <linux/i2c.h>
30 #include <linux/init.h>
31 #include <linux/jiffies.h>
32 #include <linux/kernel.h>
33 #include <linux/list.h>
34 #include <linux/module.h>
35 #include <linux/notifier.h>
36 #include <linux/slab.h>
37 #include <linux/uaccess.h>
38 #include <linux/compat.h>
41 * An i2c_dev represents an i2c_adapter ... an I2C or SMBus master, not a
42 * slave (i2c_client) with which messages will be exchanged. It's coupled
43 * with a character special file which is accessed by user mode drivers.
45 * The list of i2c_dev structures is parallel to the i2c_adapter lists
46 * maintained by the driver model, and is updated using bus notifications.
49 struct list_head list;
50 struct i2c_adapter *adap;
55 #define I2C_MINORS (MINORMASK + 1)
56 static LIST_HEAD(i2c_dev_list);
57 static DEFINE_SPINLOCK(i2c_dev_list_lock);
59 static struct i2c_dev *i2c_dev_get_by_minor(unsigned index)
61 struct i2c_dev *i2c_dev;
63 spin_lock(&i2c_dev_list_lock);
64 list_for_each_entry(i2c_dev, &i2c_dev_list, list) {
65 if (i2c_dev->adap->nr == index)
70 spin_unlock(&i2c_dev_list_lock);
74 static struct i2c_dev *get_free_i2c_dev(struct i2c_adapter *adap)
76 struct i2c_dev *i2c_dev;
78 if (adap->nr >= I2C_MINORS) {
79 printk(KERN_ERR "i2c-dev: Out of device minors (%d)\n",
81 return ERR_PTR(-ENODEV);
84 i2c_dev = kzalloc(sizeof(*i2c_dev), GFP_KERNEL);
86 return ERR_PTR(-ENOMEM);
89 spin_lock(&i2c_dev_list_lock);
90 list_add_tail(&i2c_dev->list, &i2c_dev_list);
91 spin_unlock(&i2c_dev_list_lock);
95 static void put_i2c_dev(struct i2c_dev *i2c_dev)
97 spin_lock(&i2c_dev_list_lock);
98 list_del(&i2c_dev->list);
99 spin_unlock(&i2c_dev_list_lock);
103 static ssize_t name_show(struct device *dev,
104 struct device_attribute *attr, char *buf)
106 struct i2c_dev *i2c_dev = i2c_dev_get_by_minor(MINOR(dev->devt));
110 return sprintf(buf, "%s\n", i2c_dev->adap->name);
112 static DEVICE_ATTR_RO(name);
114 static struct attribute *i2c_attrs[] = {
118 ATTRIBUTE_GROUPS(i2c);
120 /* ------------------------------------------------------------------------- */
123 * After opening an instance of this character special file, a file
124 * descriptor starts out associated only with an i2c_adapter (and bus).
126 * Using the I2C_RDWR ioctl(), you can then *immediately* issue i2c_msg
127 * traffic to any devices on the bus used by that adapter. That's because
128 * the i2c_msg vectors embed all the addressing information they need, and
129 * are submitted directly to an i2c_adapter. However, SMBus-only adapters
130 * don't support that interface.
132 * To use read()/write() system calls on that file descriptor, or to use
133 * SMBus interfaces (and work with SMBus-only hosts!), you must first issue
134 * an I2C_SLAVE (or I2C_SLAVE_FORCE) ioctl. That configures an anonymous
135 * (never registered) i2c_client so it holds the addressing information
136 * needed by those system calls and by this SMBus interface.
139 static ssize_t i2cdev_read(struct file *file, char __user *buf, size_t count,
145 struct i2c_client *client = file->private_data;
150 tmp = kmalloc(count, GFP_KERNEL);
154 pr_debug("i2c-dev: i2c-%d reading %zu bytes.\n",
155 iminor(file_inode(file)), count);
157 ret = i2c_master_recv(client, tmp, count);
159 ret = copy_to_user(buf, tmp, count) ? -EFAULT : ret;
164 static ssize_t i2cdev_write(struct file *file, const char __user *buf,
165 size_t count, loff_t *offset)
169 struct i2c_client *client = file->private_data;
174 tmp = memdup_user(buf, count);
178 pr_debug("i2c-dev: i2c-%d writing %zu bytes.\n",
179 iminor(file_inode(file)), count);
181 ret = i2c_master_send(client, tmp, count);
186 static int i2cdev_check(struct device *dev, void *addrp)
188 struct i2c_client *client = i2c_verify_client(dev);
190 if (!client || client->addr != *(unsigned int *)addrp)
193 return dev->driver ? -EBUSY : 0;
196 /* walk up mux tree */
197 static int i2cdev_check_mux_parents(struct i2c_adapter *adapter, int addr)
199 struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
202 result = device_for_each_child(&adapter->dev, &addr, i2cdev_check);
203 if (!result && parent)
204 result = i2cdev_check_mux_parents(parent, addr);
209 /* recurse down mux tree */
210 static int i2cdev_check_mux_children(struct device *dev, void *addrp)
214 if (dev->type == &i2c_adapter_type)
215 result = device_for_each_child(dev, addrp,
216 i2cdev_check_mux_children);
218 result = i2cdev_check(dev, addrp);
223 /* This address checking function differs from the one in i2c-core
224 in that it considers an address with a registered device, but no
225 driver bound to it, as NOT busy. */
226 static int i2cdev_check_addr(struct i2c_adapter *adapter, unsigned int addr)
228 struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
232 result = i2cdev_check_mux_parents(parent, addr);
235 result = device_for_each_child(&adapter->dev, &addr,
236 i2cdev_check_mux_children);
241 static noinline int i2cdev_ioctl_rdwr(struct i2c_client *client,
242 unsigned nmsgs, struct i2c_msg *msgs)
244 u8 __user **data_ptrs;
247 data_ptrs = kmalloc_array(nmsgs, sizeof(u8 __user *), GFP_KERNEL);
248 if (data_ptrs == NULL) {
254 for (i = 0; i < nmsgs; i++) {
255 /* Limit the size of the message to a sane amount */
256 if (msgs[i].len > 8192) {
261 data_ptrs[i] = (u8 __user *)msgs[i].buf;
262 msgs[i].buf = memdup_user(data_ptrs[i], msgs[i].len);
263 if (IS_ERR(msgs[i].buf)) {
264 res = PTR_ERR(msgs[i].buf);
267 /* memdup_user allocates with GFP_KERNEL, so DMA is ok */
268 msgs[i].flags |= I2C_M_DMA_SAFE;
271 * If the message length is received from the slave (similar
272 * to SMBus block read), we must ensure that the buffer will
273 * be large enough to cope with a message length of
274 * I2C_SMBUS_BLOCK_MAX as this is the maximum underlying bus
275 * drivers allow. The first byte in the buffer must be
276 * pre-filled with the number of extra bytes, which must be
277 * at least one to hold the message length, but can be
278 * greater (for example to account for a checksum byte at
279 * the end of the message.)
281 if (msgs[i].flags & I2C_M_RECV_LEN) {
282 if (!(msgs[i].flags & I2C_M_RD) ||
283 msgs[i].len < 1 || msgs[i].buf[0] < 1 ||
284 msgs[i].len < msgs[i].buf[0] +
285 I2C_SMBUS_BLOCK_MAX) {
290 msgs[i].len = msgs[i].buf[0];
295 for (j = 0; j < i; ++j)
302 res = i2c_transfer(client->adapter, msgs, nmsgs);
304 if (res >= 0 && (msgs[i].flags & I2C_M_RD)) {
305 if (copy_to_user(data_ptrs[i], msgs[i].buf,
316 static noinline int i2cdev_ioctl_smbus(struct i2c_client *client,
317 u8 read_write, u8 command, u32 size,
318 union i2c_smbus_data __user *data)
320 union i2c_smbus_data temp = {};
323 if ((size != I2C_SMBUS_BYTE) &&
324 (size != I2C_SMBUS_QUICK) &&
325 (size != I2C_SMBUS_BYTE_DATA) &&
326 (size != I2C_SMBUS_WORD_DATA) &&
327 (size != I2C_SMBUS_PROC_CALL) &&
328 (size != I2C_SMBUS_BLOCK_DATA) &&
329 (size != I2C_SMBUS_I2C_BLOCK_BROKEN) &&
330 (size != I2C_SMBUS_I2C_BLOCK_DATA) &&
331 (size != I2C_SMBUS_BLOCK_PROC_CALL)) {
332 dev_dbg(&client->adapter->dev,
333 "size out of range (%x) in ioctl I2C_SMBUS.\n",
337 /* Note that I2C_SMBUS_READ and I2C_SMBUS_WRITE are 0 and 1,
338 so the check is valid if size==I2C_SMBUS_QUICK too. */
339 if ((read_write != I2C_SMBUS_READ) &&
340 (read_write != I2C_SMBUS_WRITE)) {
341 dev_dbg(&client->adapter->dev,
342 "read_write out of range (%x) in ioctl I2C_SMBUS.\n",
347 /* Note that command values are always valid! */
349 if ((size == I2C_SMBUS_QUICK) ||
350 ((size == I2C_SMBUS_BYTE) &&
351 (read_write == I2C_SMBUS_WRITE)))
352 /* These are special: we do not use data */
353 return i2c_smbus_xfer(client->adapter, client->addr,
354 client->flags, read_write,
355 command, size, NULL);
358 dev_dbg(&client->adapter->dev,
359 "data is NULL pointer in ioctl I2C_SMBUS.\n");
363 if ((size == I2C_SMBUS_BYTE_DATA) ||
364 (size == I2C_SMBUS_BYTE))
365 datasize = sizeof(data->byte);
366 else if ((size == I2C_SMBUS_WORD_DATA) ||
367 (size == I2C_SMBUS_PROC_CALL))
368 datasize = sizeof(data->word);
369 else /* size == smbus block, i2c block, or block proc. call */
370 datasize = sizeof(data->block);
372 if ((size == I2C_SMBUS_PROC_CALL) ||
373 (size == I2C_SMBUS_BLOCK_PROC_CALL) ||
374 (size == I2C_SMBUS_I2C_BLOCK_DATA) ||
375 (read_write == I2C_SMBUS_WRITE)) {
376 if (copy_from_user(&temp, data, datasize))
379 if (size == I2C_SMBUS_I2C_BLOCK_BROKEN) {
380 /* Convert old I2C block commands to the new
381 convention. This preserves binary compatibility. */
382 size = I2C_SMBUS_I2C_BLOCK_DATA;
383 if (read_write == I2C_SMBUS_READ)
384 temp.block[0] = I2C_SMBUS_BLOCK_MAX;
386 res = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
387 read_write, command, size, &temp);
388 if (!res && ((size == I2C_SMBUS_PROC_CALL) ||
389 (size == I2C_SMBUS_BLOCK_PROC_CALL) ||
390 (read_write == I2C_SMBUS_READ))) {
391 if (copy_to_user(data, &temp, datasize))
397 static long i2cdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
399 struct i2c_client *client = file->private_data;
402 dev_dbg(&client->adapter->dev, "ioctl, cmd=0x%02x, arg=0x%02lx\n",
407 case I2C_SLAVE_FORCE:
409 (((client->flags & I2C_M_TEN) == 0) && arg > 0x7f))
411 if (cmd == I2C_SLAVE && i2cdev_check_addr(client->adapter, arg))
413 /* REVISIT: address could become busy later */
418 client->flags |= I2C_M_TEN;
420 client->flags &= ~I2C_M_TEN;
424 * Setting the PEC flag here won't affect kernel drivers,
425 * which will be using the i2c_client node registered with
426 * the driver model core. Likewise, when that client has
427 * the PEC flag already set, the i2c-dev driver won't see
428 * (or use) this setting.
431 client->flags |= I2C_CLIENT_PEC;
433 client->flags &= ~I2C_CLIENT_PEC;
436 funcs = i2c_get_functionality(client->adapter);
437 return put_user(funcs, (unsigned long __user *)arg);
440 struct i2c_rdwr_ioctl_data rdwr_arg;
441 struct i2c_msg *rdwr_pa;
443 if (copy_from_user(&rdwr_arg,
444 (struct i2c_rdwr_ioctl_data __user *)arg,
448 /* Put an arbitrary limit on the number of messages that can
450 if (rdwr_arg.nmsgs > I2C_RDWR_IOCTL_MAX_MSGS)
453 rdwr_pa = memdup_user(rdwr_arg.msgs,
454 rdwr_arg.nmsgs * sizeof(struct i2c_msg));
456 return PTR_ERR(rdwr_pa);
458 return i2cdev_ioctl_rdwr(client, rdwr_arg.nmsgs, rdwr_pa);
462 struct i2c_smbus_ioctl_data data_arg;
463 if (copy_from_user(&data_arg,
464 (struct i2c_smbus_ioctl_data __user *) arg,
465 sizeof(struct i2c_smbus_ioctl_data)))
467 return i2cdev_ioctl_smbus(client, data_arg.read_write,
476 client->adapter->retries = arg;
482 /* For historical reasons, user-space sets the timeout
483 * value in units of 10 ms.
485 client->adapter->timeout = msecs_to_jiffies(arg * 10);
488 /* NOTE: returning a fault code here could cause trouble
489 * in buggy userspace code. Some old kernel bugs returned
490 * zero in this case, and userspace code might accidentally
491 * have depended on that bug.
500 struct i2c_smbus_ioctl_data32 {
504 compat_caddr_t data; /* union i2c_smbus_data *data */
514 struct i2c_rdwr_ioctl_data32 {
515 compat_caddr_t msgs; /* struct i2c_msg __user *msgs */
519 static long compat_i2cdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
521 struct i2c_client *client = file->private_data;
525 funcs = i2c_get_functionality(client->adapter);
526 return put_user(funcs, (compat_ulong_t __user *)arg);
528 struct i2c_rdwr_ioctl_data32 rdwr_arg;
530 struct i2c_msg *rdwr_pa;
533 if (copy_from_user(&rdwr_arg,
534 (struct i2c_rdwr_ioctl_data32 __user *)arg,
538 if (rdwr_arg.nmsgs > I2C_RDWR_IOCTL_MAX_MSGS)
541 rdwr_pa = kmalloc_array(rdwr_arg.nmsgs, sizeof(struct i2c_msg),
546 p = compat_ptr(rdwr_arg.msgs);
547 for (i = 0; i < rdwr_arg.nmsgs; i++) {
548 struct i2c_msg32 umsg;
549 if (copy_from_user(&umsg, p + i, sizeof(umsg))) {
553 rdwr_pa[i] = (struct i2c_msg) {
557 .buf = compat_ptr(umsg.buf)
561 return i2cdev_ioctl_rdwr(client, rdwr_arg.nmsgs, rdwr_pa);
564 struct i2c_smbus_ioctl_data32 data32;
565 if (copy_from_user(&data32,
569 return i2cdev_ioctl_smbus(client, data32.read_write,
572 compat_ptr(data32.data));
575 return i2cdev_ioctl(file, cmd, arg);
579 #define compat_i2cdev_ioctl NULL
582 static int i2cdev_open(struct inode *inode, struct file *file)
584 unsigned int minor = iminor(inode);
585 struct i2c_client *client;
586 struct i2c_adapter *adap;
588 adap = i2c_get_adapter(minor);
592 /* This creates an anonymous i2c_client, which may later be
593 * pointed to some address using I2C_SLAVE or I2C_SLAVE_FORCE.
595 * This client is ** NEVER REGISTERED ** with the driver model
596 * or I2C core code!! It just holds private copies of addressing
597 * information and maybe a PEC flag.
599 client = kzalloc(sizeof(*client), GFP_KERNEL);
601 i2c_put_adapter(adap);
604 snprintf(client->name, I2C_NAME_SIZE, "i2c-dev %d", adap->nr);
606 client->adapter = adap;
607 file->private_data = client;
612 static int i2cdev_release(struct inode *inode, struct file *file)
614 struct i2c_client *client = file->private_data;
616 i2c_put_adapter(client->adapter);
618 file->private_data = NULL;
623 static const struct file_operations i2cdev_fops = {
624 .owner = THIS_MODULE,
627 .write = i2cdev_write,
628 .unlocked_ioctl = i2cdev_ioctl,
629 .compat_ioctl = compat_i2cdev_ioctl,
631 .release = i2cdev_release,
634 /* ------------------------------------------------------------------------- */
636 static struct class *i2c_dev_class;
638 static int i2cdev_attach_adapter(struct device *dev, void *dummy)
640 struct i2c_adapter *adap;
641 struct i2c_dev *i2c_dev;
644 if (dev->type != &i2c_adapter_type)
646 adap = to_i2c_adapter(dev);
648 i2c_dev = get_free_i2c_dev(adap);
650 return PTR_ERR(i2c_dev);
652 cdev_init(&i2c_dev->cdev, &i2cdev_fops);
653 i2c_dev->cdev.owner = THIS_MODULE;
654 res = cdev_add(&i2c_dev->cdev, MKDEV(I2C_MAJOR, adap->nr), 1);
658 /* register this i2c device with the driver core */
659 i2c_dev->dev = device_create(i2c_dev_class, &adap->dev,
660 MKDEV(I2C_MAJOR, adap->nr), NULL,
662 if (IS_ERR(i2c_dev->dev)) {
663 res = PTR_ERR(i2c_dev->dev);
667 pr_debug("i2c-dev: adapter [%s] registered as minor %d\n",
668 adap->name, adap->nr);
671 cdev_del(&i2c_dev->cdev);
673 put_i2c_dev(i2c_dev);
677 static int i2cdev_detach_adapter(struct device *dev, void *dummy)
679 struct i2c_adapter *adap;
680 struct i2c_dev *i2c_dev;
682 if (dev->type != &i2c_adapter_type)
684 adap = to_i2c_adapter(dev);
686 i2c_dev = i2c_dev_get_by_minor(adap->nr);
687 if (!i2c_dev) /* attach_adapter must have failed */
690 cdev_del(&i2c_dev->cdev);
691 put_i2c_dev(i2c_dev);
692 device_destroy(i2c_dev_class, MKDEV(I2C_MAJOR, adap->nr));
694 pr_debug("i2c-dev: adapter [%s] unregistered\n", adap->name);
698 static int i2cdev_notifier_call(struct notifier_block *nb, unsigned long action,
701 struct device *dev = data;
704 case BUS_NOTIFY_ADD_DEVICE:
705 return i2cdev_attach_adapter(dev, NULL);
706 case BUS_NOTIFY_DEL_DEVICE:
707 return i2cdev_detach_adapter(dev, NULL);
713 static struct notifier_block i2cdev_notifier = {
714 .notifier_call = i2cdev_notifier_call,
717 /* ------------------------------------------------------------------------- */
720 * module load/unload record keeping
723 static int __init i2c_dev_init(void)
727 printk(KERN_INFO "i2c /dev entries driver\n");
729 res = register_chrdev_region(MKDEV(I2C_MAJOR, 0), I2C_MINORS, "i2c");
733 i2c_dev_class = class_create(THIS_MODULE, "i2c-dev");
734 if (IS_ERR(i2c_dev_class)) {
735 res = PTR_ERR(i2c_dev_class);
736 goto out_unreg_chrdev;
738 i2c_dev_class->dev_groups = i2c_groups;
740 /* Keep track of adapters which will be added or removed later */
741 res = bus_register_notifier(&i2c_bus_type, &i2cdev_notifier);
743 goto out_unreg_class;
745 /* Bind to already existing adapters right away */
746 i2c_for_each_dev(NULL, i2cdev_attach_adapter);
751 class_destroy(i2c_dev_class);
753 unregister_chrdev_region(MKDEV(I2C_MAJOR, 0), I2C_MINORS);
755 printk(KERN_ERR "%s: Driver Initialisation failed\n", __FILE__);
759 static void __exit i2c_dev_exit(void)
761 bus_unregister_notifier(&i2c_bus_type, &i2cdev_notifier);
762 i2c_for_each_dev(NULL, i2cdev_detach_adapter);
763 class_destroy(i2c_dev_class);
764 unregister_chrdev_region(MKDEV(I2C_MAJOR, 0), I2C_MINORS);
767 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and "
768 "Simon G. Vogl <simon@tk.uni-linz.ac.at>");
769 MODULE_DESCRIPTION("I2C /dev entries driver");
770 MODULE_LICENSE("GPL");
772 module_init(i2c_dev_init);
773 module_exit(i2c_dev_exit);