1 // SPDX-License-Identifier: GPL-2.0-or-later
3 i2c-dev.c - i2c-bus driver, char device interface
5 Copyright (C) 1995-97 Simon G. Vogl
6 Copyright (C) 1998-99 Frodo Looijaard <frodol@dds.nl>
7 Copyright (C) 2003 Greg Kroah-Hartman <greg@kroah.com>
11 /* Note that this is a complete rewrite of Simon Vogl's i2c-dev module.
12 But I have used so much of his original code and ideas that it seems
13 only fair to recognize him as co-author -- Frodo */
15 /* The I2C_RDWR ioctl code is written by Kolja Waschk <waschk@telos.de> */
17 #include <linux/cdev.h>
18 #include <linux/compat.h>
19 #include <linux/device.h>
21 #include <linux/i2c-dev.h>
22 #include <linux/i2c.h>
23 #include <linux/init.h>
24 #include <linux/jiffies.h>
25 #include <linux/kernel.h>
26 #include <linux/list.h>
27 #include <linux/module.h>
28 #include <linux/notifier.h>
29 #include <linux/slab.h>
30 #include <linux/uaccess.h>
33 * An i2c_dev represents an i2c_adapter ... an I2C or SMBus master, not a
34 * slave (i2c_client) with which messages will be exchanged. It's coupled
35 * with a character special file which is accessed by user mode drivers.
37 * The list of i2c_dev structures is parallel to the i2c_adapter lists
38 * maintained by the driver model, and is updated using bus notifications.
41 struct list_head list;
42 struct i2c_adapter *adap;
47 #define I2C_MINORS (MINORMASK + 1)
48 static LIST_HEAD(i2c_dev_list);
49 static DEFINE_SPINLOCK(i2c_dev_list_lock);
51 static struct i2c_dev *i2c_dev_get_by_minor(unsigned index)
53 struct i2c_dev *i2c_dev;
55 spin_lock(&i2c_dev_list_lock);
56 list_for_each_entry(i2c_dev, &i2c_dev_list, list) {
57 if (i2c_dev->adap->nr == index)
62 spin_unlock(&i2c_dev_list_lock);
66 static struct i2c_dev *get_free_i2c_dev(struct i2c_adapter *adap)
68 struct i2c_dev *i2c_dev;
70 if (adap->nr >= I2C_MINORS) {
71 printk(KERN_ERR "i2c-dev: Out of device minors (%d)\n",
73 return ERR_PTR(-ENODEV);
76 i2c_dev = kzalloc(sizeof(*i2c_dev), GFP_KERNEL);
78 return ERR_PTR(-ENOMEM);
81 spin_lock(&i2c_dev_list_lock);
82 list_add_tail(&i2c_dev->list, &i2c_dev_list);
83 spin_unlock(&i2c_dev_list_lock);
87 static void put_i2c_dev(struct i2c_dev *i2c_dev, bool del_cdev)
89 spin_lock(&i2c_dev_list_lock);
90 list_del(&i2c_dev->list);
91 spin_unlock(&i2c_dev_list_lock);
93 cdev_device_del(&i2c_dev->cdev, &i2c_dev->dev);
94 put_device(&i2c_dev->dev);
97 static ssize_t name_show(struct device *dev,
98 struct device_attribute *attr, char *buf)
100 struct i2c_dev *i2c_dev = i2c_dev_get_by_minor(MINOR(dev->devt));
104 return sprintf(buf, "%s\n", i2c_dev->adap->name);
106 static DEVICE_ATTR_RO(name);
108 static struct attribute *i2c_attrs[] = {
112 ATTRIBUTE_GROUPS(i2c);
114 /* ------------------------------------------------------------------------- */
117 * After opening an instance of this character special file, a file
118 * descriptor starts out associated only with an i2c_adapter (and bus).
120 * Using the I2C_RDWR ioctl(), you can then *immediately* issue i2c_msg
121 * traffic to any devices on the bus used by that adapter. That's because
122 * the i2c_msg vectors embed all the addressing information they need, and
123 * are submitted directly to an i2c_adapter. However, SMBus-only adapters
124 * don't support that interface.
126 * To use read()/write() system calls on that file descriptor, or to use
127 * SMBus interfaces (and work with SMBus-only hosts!), you must first issue
128 * an I2C_SLAVE (or I2C_SLAVE_FORCE) ioctl. That configures an anonymous
129 * (never registered) i2c_client so it holds the addressing information
130 * needed by those system calls and by this SMBus interface.
133 static ssize_t i2cdev_read(struct file *file, char __user *buf, size_t count,
139 struct i2c_client *client = file->private_data;
144 tmp = kzalloc(count, GFP_KERNEL);
148 pr_debug("i2c-dev: i2c-%d reading %zu bytes.\n",
149 iminor(file_inode(file)), count);
151 ret = i2c_master_recv(client, tmp, count);
153 if (copy_to_user(buf, tmp, ret))
159 static ssize_t i2cdev_write(struct file *file, const char __user *buf,
160 size_t count, loff_t *offset)
164 struct i2c_client *client = file->private_data;
169 tmp = memdup_user(buf, count);
173 pr_debug("i2c-dev: i2c-%d writing %zu bytes.\n",
174 iminor(file_inode(file)), count);
176 ret = i2c_master_send(client, tmp, count);
181 static int i2cdev_check(struct device *dev, void *addrp)
183 struct i2c_client *client = i2c_verify_client(dev);
185 if (!client || client->addr != *(unsigned int *)addrp)
188 return dev->driver ? -EBUSY : 0;
191 /* walk up mux tree */
192 static int i2cdev_check_mux_parents(struct i2c_adapter *adapter, int addr)
194 struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
197 result = device_for_each_child(&adapter->dev, &addr, i2cdev_check);
198 if (!result && parent)
199 result = i2cdev_check_mux_parents(parent, addr);
204 /* recurse down mux tree */
205 static int i2cdev_check_mux_children(struct device *dev, void *addrp)
209 if (dev->type == &i2c_adapter_type)
210 result = device_for_each_child(dev, addrp,
211 i2cdev_check_mux_children);
213 result = i2cdev_check(dev, addrp);
218 /* This address checking function differs from the one in i2c-core
219 in that it considers an address with a registered device, but no
220 driver bound to it, as NOT busy. */
221 static int i2cdev_check_addr(struct i2c_adapter *adapter, unsigned int addr)
223 struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
227 result = i2cdev_check_mux_parents(parent, addr);
230 result = device_for_each_child(&adapter->dev, &addr,
231 i2cdev_check_mux_children);
236 static noinline int i2cdev_ioctl_rdwr(struct i2c_client *client,
237 unsigned nmsgs, struct i2c_msg *msgs)
239 u8 __user **data_ptrs;
242 data_ptrs = kmalloc_array(nmsgs, sizeof(u8 __user *), GFP_KERNEL);
243 if (data_ptrs == NULL) {
249 for (i = 0; i < nmsgs; i++) {
250 /* Limit the size of the message to a sane amount */
251 if (msgs[i].len > 8192) {
256 data_ptrs[i] = (u8 __user *)msgs[i].buf;
257 msgs[i].buf = memdup_user(data_ptrs[i], msgs[i].len);
258 if (IS_ERR(msgs[i].buf)) {
259 res = PTR_ERR(msgs[i].buf);
262 /* memdup_user allocates with GFP_KERNEL, so DMA is ok */
263 msgs[i].flags |= I2C_M_DMA_SAFE;
266 * If the message length is received from the slave (similar
267 * to SMBus block read), we must ensure that the buffer will
268 * be large enough to cope with a message length of
269 * I2C_SMBUS_BLOCK_MAX as this is the maximum underlying bus
270 * drivers allow. The first byte in the buffer must be
271 * pre-filled with the number of extra bytes, which must be
272 * at least one to hold the message length, but can be
273 * greater (for example to account for a checksum byte at
274 * the end of the message.)
276 if (msgs[i].flags & I2C_M_RECV_LEN) {
277 if (!(msgs[i].flags & I2C_M_RD) ||
278 msgs[i].len < 1 || msgs[i].buf[0] < 1 ||
279 msgs[i].len < msgs[i].buf[0] +
280 I2C_SMBUS_BLOCK_MAX) {
286 msgs[i].len = msgs[i].buf[0];
291 for (j = 0; j < i; ++j)
298 res = i2c_transfer(client->adapter, msgs, nmsgs);
300 if (res >= 0 && (msgs[i].flags & I2C_M_RD)) {
301 if (copy_to_user(data_ptrs[i], msgs[i].buf,
312 static noinline int i2cdev_ioctl_smbus(struct i2c_client *client,
313 u8 read_write, u8 command, u32 size,
314 union i2c_smbus_data __user *data)
316 union i2c_smbus_data temp = {};
319 if ((size != I2C_SMBUS_BYTE) &&
320 (size != I2C_SMBUS_QUICK) &&
321 (size != I2C_SMBUS_BYTE_DATA) &&
322 (size != I2C_SMBUS_WORD_DATA) &&
323 (size != I2C_SMBUS_PROC_CALL) &&
324 (size != I2C_SMBUS_BLOCK_DATA) &&
325 (size != I2C_SMBUS_I2C_BLOCK_BROKEN) &&
326 (size != I2C_SMBUS_I2C_BLOCK_DATA) &&
327 (size != I2C_SMBUS_BLOCK_PROC_CALL)) {
328 dev_dbg(&client->adapter->dev,
329 "size out of range (%x) in ioctl I2C_SMBUS.\n",
333 /* Note that I2C_SMBUS_READ and I2C_SMBUS_WRITE are 0 and 1,
334 so the check is valid if size==I2C_SMBUS_QUICK too. */
335 if ((read_write != I2C_SMBUS_READ) &&
336 (read_write != I2C_SMBUS_WRITE)) {
337 dev_dbg(&client->adapter->dev,
338 "read_write out of range (%x) in ioctl I2C_SMBUS.\n",
343 /* Note that command values are always valid! */
345 if ((size == I2C_SMBUS_QUICK) ||
346 ((size == I2C_SMBUS_BYTE) &&
347 (read_write == I2C_SMBUS_WRITE)))
348 /* These are special: we do not use data */
349 return i2c_smbus_xfer(client->adapter, client->addr,
350 client->flags, read_write,
351 command, size, NULL);
354 dev_dbg(&client->adapter->dev,
355 "data is NULL pointer in ioctl I2C_SMBUS.\n");
359 if ((size == I2C_SMBUS_BYTE_DATA) ||
360 (size == I2C_SMBUS_BYTE))
361 datasize = sizeof(data->byte);
362 else if ((size == I2C_SMBUS_WORD_DATA) ||
363 (size == I2C_SMBUS_PROC_CALL))
364 datasize = sizeof(data->word);
365 else /* size == smbus block, i2c block, or block proc. call */
366 datasize = sizeof(data->block);
368 if ((size == I2C_SMBUS_PROC_CALL) ||
369 (size == I2C_SMBUS_BLOCK_PROC_CALL) ||
370 (size == I2C_SMBUS_I2C_BLOCK_DATA) ||
371 (read_write == I2C_SMBUS_WRITE)) {
372 if (copy_from_user(&temp, data, datasize))
375 if (size == I2C_SMBUS_I2C_BLOCK_BROKEN) {
376 /* Convert old I2C block commands to the new
377 convention. This preserves binary compatibility. */
378 size = I2C_SMBUS_I2C_BLOCK_DATA;
379 if (read_write == I2C_SMBUS_READ)
380 temp.block[0] = I2C_SMBUS_BLOCK_MAX;
382 res = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
383 read_write, command, size, &temp);
384 if (!res && ((size == I2C_SMBUS_PROC_CALL) ||
385 (size == I2C_SMBUS_BLOCK_PROC_CALL) ||
386 (read_write == I2C_SMBUS_READ))) {
387 if (copy_to_user(data, &temp, datasize))
393 static long i2cdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
395 struct i2c_client *client = file->private_data;
398 dev_dbg(&client->adapter->dev, "ioctl, cmd=0x%02x, arg=0x%02lx\n",
403 case I2C_SLAVE_FORCE:
405 (((client->flags & I2C_M_TEN) == 0) && arg > 0x7f))
407 if (cmd == I2C_SLAVE && i2cdev_check_addr(client->adapter, arg))
409 /* REVISIT: address could become busy later */
414 client->flags |= I2C_M_TEN;
416 client->flags &= ~I2C_M_TEN;
420 * Setting the PEC flag here won't affect kernel drivers,
421 * which will be using the i2c_client node registered with
422 * the driver model core. Likewise, when that client has
423 * the PEC flag already set, the i2c-dev driver won't see
424 * (or use) this setting.
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 struct i2c_rdwr_ioctl_data rdwr_arg;
437 struct i2c_msg *rdwr_pa;
439 if (copy_from_user(&rdwr_arg,
440 (struct i2c_rdwr_ioctl_data __user *)arg,
444 if (!rdwr_arg.msgs || rdwr_arg.nmsgs == 0)
448 * Put an arbitrary limit on the number of messages that can
451 if (rdwr_arg.nmsgs > I2C_RDWR_IOCTL_MAX_MSGS)
454 rdwr_pa = memdup_user(rdwr_arg.msgs,
455 rdwr_arg.nmsgs * sizeof(struct i2c_msg));
457 return PTR_ERR(rdwr_pa);
459 return i2cdev_ioctl_rdwr(client, rdwr_arg.nmsgs, rdwr_pa);
463 struct i2c_smbus_ioctl_data data_arg;
464 if (copy_from_user(&data_arg,
465 (struct i2c_smbus_ioctl_data __user *) arg,
466 sizeof(struct i2c_smbus_ioctl_data)))
468 return i2cdev_ioctl_smbus(client, data_arg.read_write,
477 client->adapter->retries = arg;
483 /* For historical reasons, user-space sets the timeout
484 * value in units of 10 ms.
486 client->adapter->timeout = msecs_to_jiffies(arg * 10);
489 /* NOTE: returning a fault code here could cause trouble
490 * in buggy userspace code. Some old kernel bugs returned
491 * zero in this case, and userspace code might accidentally
492 * have depended on that bug.
501 struct i2c_smbus_ioctl_data32 {
505 compat_caddr_t data; /* union i2c_smbus_data *data */
515 struct i2c_rdwr_ioctl_data32 {
516 compat_caddr_t msgs; /* struct i2c_msg __user *msgs */
520 static long compat_i2cdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
522 struct i2c_client *client = file->private_data;
526 funcs = i2c_get_functionality(client->adapter);
527 return put_user(funcs, (compat_ulong_t __user *)arg);
529 struct i2c_rdwr_ioctl_data32 rdwr_arg;
531 struct i2c_msg *rdwr_pa;
534 if (copy_from_user(&rdwr_arg,
535 (struct i2c_rdwr_ioctl_data32 __user *)arg,
539 if (!rdwr_arg.msgs || rdwr_arg.nmsgs == 0)
542 if (rdwr_arg.nmsgs > I2C_RDWR_IOCTL_MAX_MSGS)
545 rdwr_pa = kmalloc_array(rdwr_arg.nmsgs, sizeof(struct i2c_msg),
550 p = compat_ptr(rdwr_arg.msgs);
551 for (i = 0; i < rdwr_arg.nmsgs; i++) {
552 struct i2c_msg32 umsg;
553 if (copy_from_user(&umsg, p + i, sizeof(umsg))) {
557 rdwr_pa[i] = (struct i2c_msg) {
561 .buf = compat_ptr(umsg.buf)
565 return i2cdev_ioctl_rdwr(client, rdwr_arg.nmsgs, rdwr_pa);
568 struct i2c_smbus_ioctl_data32 data32;
569 if (copy_from_user(&data32,
573 return i2cdev_ioctl_smbus(client, data32.read_write,
576 compat_ptr(data32.data));
579 return i2cdev_ioctl(file, cmd, arg);
583 #define compat_i2cdev_ioctl NULL
586 static int i2cdev_open(struct inode *inode, struct file *file)
588 unsigned int minor = iminor(inode);
589 struct i2c_client *client;
590 struct i2c_adapter *adap;
592 adap = i2c_get_adapter(minor);
596 /* This creates an anonymous i2c_client, which may later be
597 * pointed to some address using I2C_SLAVE or I2C_SLAVE_FORCE.
599 * This client is ** NEVER REGISTERED ** with the driver model
600 * or I2C core code!! It just holds private copies of addressing
601 * information and maybe a PEC flag.
603 client = kzalloc(sizeof(*client), GFP_KERNEL);
605 i2c_put_adapter(adap);
608 snprintf(client->name, I2C_NAME_SIZE, "i2c-dev %d", adap->nr);
610 client->adapter = adap;
611 file->private_data = client;
616 static int i2cdev_release(struct inode *inode, struct file *file)
618 struct i2c_client *client = file->private_data;
620 i2c_put_adapter(client->adapter);
622 file->private_data = NULL;
627 static const struct file_operations i2cdev_fops = {
628 .owner = THIS_MODULE,
631 .write = i2cdev_write,
632 .unlocked_ioctl = i2cdev_ioctl,
633 .compat_ioctl = compat_i2cdev_ioctl,
635 .release = i2cdev_release,
638 /* ------------------------------------------------------------------------- */
640 static struct class *i2c_dev_class;
642 static void i2cdev_dev_release(struct device *dev)
644 struct i2c_dev *i2c_dev;
646 i2c_dev = container_of(dev, struct i2c_dev, dev);
650 static int i2cdev_attach_adapter(struct device *dev, void *dummy)
652 struct i2c_adapter *adap;
653 struct i2c_dev *i2c_dev;
656 if (dev->type != &i2c_adapter_type)
658 adap = to_i2c_adapter(dev);
660 i2c_dev = get_free_i2c_dev(adap);
662 return PTR_ERR(i2c_dev);
664 cdev_init(&i2c_dev->cdev, &i2cdev_fops);
665 i2c_dev->cdev.owner = THIS_MODULE;
667 device_initialize(&i2c_dev->dev);
668 i2c_dev->dev.devt = MKDEV(I2C_MAJOR, adap->nr);
669 i2c_dev->dev.class = i2c_dev_class;
670 i2c_dev->dev.parent = &adap->dev;
671 i2c_dev->dev.release = i2cdev_dev_release;
672 dev_set_name(&i2c_dev->dev, "i2c-%d", adap->nr);
674 res = cdev_device_add(&i2c_dev->cdev, &i2c_dev->dev);
676 put_i2c_dev(i2c_dev, false);
680 pr_debug("i2c-dev: adapter [%s] registered as minor %d\n",
681 adap->name, adap->nr);
685 static int i2cdev_detach_adapter(struct device *dev, void *dummy)
687 struct i2c_adapter *adap;
688 struct i2c_dev *i2c_dev;
690 if (dev->type != &i2c_adapter_type)
692 adap = to_i2c_adapter(dev);
694 i2c_dev = i2c_dev_get_by_minor(adap->nr);
695 if (!i2c_dev) /* attach_adapter must have failed */
698 put_i2c_dev(i2c_dev, true);
700 pr_debug("i2c-dev: adapter [%s] unregistered\n", adap->name);
704 static int i2cdev_notifier_call(struct notifier_block *nb, unsigned long action,
707 struct device *dev = data;
710 case BUS_NOTIFY_ADD_DEVICE:
711 return i2cdev_attach_adapter(dev, NULL);
712 case BUS_NOTIFY_DEL_DEVICE:
713 return i2cdev_detach_adapter(dev, NULL);
719 static struct notifier_block i2cdev_notifier = {
720 .notifier_call = i2cdev_notifier_call,
723 /* ------------------------------------------------------------------------- */
726 * module load/unload record keeping
729 static int __init i2c_dev_init(void)
733 printk(KERN_INFO "i2c /dev entries driver\n");
735 res = register_chrdev_region(MKDEV(I2C_MAJOR, 0), I2C_MINORS, "i2c");
739 i2c_dev_class = class_create(THIS_MODULE, "i2c-dev");
740 if (IS_ERR(i2c_dev_class)) {
741 res = PTR_ERR(i2c_dev_class);
742 goto out_unreg_chrdev;
744 i2c_dev_class->dev_groups = i2c_groups;
746 /* Keep track of adapters which will be added or removed later */
747 res = bus_register_notifier(&i2c_bus_type, &i2cdev_notifier);
749 goto out_unreg_class;
751 /* Bind to already existing adapters right away */
752 i2c_for_each_dev(NULL, i2cdev_attach_adapter);
757 class_destroy(i2c_dev_class);
759 unregister_chrdev_region(MKDEV(I2C_MAJOR, 0), I2C_MINORS);
761 printk(KERN_ERR "%s: Driver Initialisation failed\n", __FILE__);
765 static void __exit i2c_dev_exit(void)
767 bus_unregister_notifier(&i2c_bus_type, &i2cdev_notifier);
768 i2c_for_each_dev(NULL, i2cdev_detach_adapter);
769 class_destroy(i2c_dev_class);
770 unregister_chrdev_region(MKDEV(I2C_MAJOR, 0), I2C_MINORS);
773 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl>");
774 MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>");
775 MODULE_DESCRIPTION("I2C /dev entries driver");
776 MODULE_LICENSE("GPL");
778 module_init(i2c_dev_init);
779 module_exit(i2c_dev_exit);