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
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, bool del_cdev)
97 spin_lock(&i2c_dev_list_lock);
98 list_del(&i2c_dev->list);
99 spin_unlock(&i2c_dev_list_lock);
101 cdev_device_del(&i2c_dev->cdev, &i2c_dev->dev);
102 put_device(&i2c_dev->dev);
105 static ssize_t name_show(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_RO(name);
116 static struct attribute *i2c_attrs[] = {
120 ATTRIBUTE_GROUPS(i2c);
122 /* ------------------------------------------------------------------------- */
125 * After opening an instance of this character special file, a file
126 * descriptor starts out associated only with an i2c_adapter (and bus).
128 * Using the I2C_RDWR ioctl(), you can then *immediately* issue i2c_msg
129 * traffic to any devices on the bus used by that adapter. That's because
130 * the i2c_msg vectors embed all the addressing information they need, and
131 * are submitted directly to an i2c_adapter. However, SMBus-only adapters
132 * don't support that interface.
134 * To use read()/write() system calls on that file descriptor, or to use
135 * SMBus interfaces (and work with SMBus-only hosts!), you must first issue
136 * an I2C_SLAVE (or I2C_SLAVE_FORCE) ioctl. That configures an anonymous
137 * (never registered) i2c_client so it holds the addressing information
138 * needed by those system calls and by this SMBus interface.
141 static ssize_t i2cdev_read(struct file *file, char __user *buf, size_t count,
147 struct i2c_client *client = file->private_data;
152 tmp = kzalloc(count, GFP_KERNEL);
156 pr_debug("i2c-dev: i2c-%d reading %zu bytes.\n",
157 iminor(file_inode(file)), count);
159 ret = i2c_master_recv(client, tmp, count);
161 if (copy_to_user(buf, tmp, ret))
167 static ssize_t i2cdev_write(struct file *file, const char __user *buf,
168 size_t count, loff_t *offset)
172 struct i2c_client *client = file->private_data;
177 tmp = memdup_user(buf, count);
181 pr_debug("i2c-dev: i2c-%d writing %zu bytes.\n",
182 iminor(file_inode(file)), count);
184 ret = i2c_master_send(client, tmp, count);
189 static int i2cdev_check(struct device *dev, void *addrp)
191 struct i2c_client *client = i2c_verify_client(dev);
193 if (!client || client->addr != *(unsigned int *)addrp)
196 return dev->driver ? -EBUSY : 0;
199 /* walk up mux tree */
200 static int i2cdev_check_mux_parents(struct i2c_adapter *adapter, int addr)
202 struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
205 result = device_for_each_child(&adapter->dev, &addr, i2cdev_check);
206 if (!result && parent)
207 result = i2cdev_check_mux_parents(parent, addr);
212 /* recurse down mux tree */
213 static int i2cdev_check_mux_children(struct device *dev, void *addrp)
217 if (dev->type == &i2c_adapter_type)
218 result = device_for_each_child(dev, addrp,
219 i2cdev_check_mux_children);
221 result = i2cdev_check(dev, addrp);
226 /* This address checking function differs from the one in i2c-core
227 in that it considers an address with a registered device, but no
228 driver bound to it, as NOT busy. */
229 static int i2cdev_check_addr(struct i2c_adapter *adapter, unsigned int addr)
231 struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
235 result = i2cdev_check_mux_parents(parent, addr);
238 result = device_for_each_child(&adapter->dev, &addr,
239 i2cdev_check_mux_children);
244 static noinline int i2cdev_ioctl_rdwr(struct i2c_client *client,
245 unsigned nmsgs, struct i2c_msg *msgs)
247 u8 __user **data_ptrs;
250 data_ptrs = kmalloc_array(nmsgs, sizeof(u8 __user *), GFP_KERNEL);
251 if (data_ptrs == NULL) {
257 for (i = 0; i < nmsgs; i++) {
258 /* Limit the size of the message to a sane amount */
259 if (msgs[i].len > 8192) {
264 data_ptrs[i] = (u8 __user *)msgs[i].buf;
265 msgs[i].buf = memdup_user(data_ptrs[i], msgs[i].len);
266 if (IS_ERR(msgs[i].buf)) {
267 res = PTR_ERR(msgs[i].buf);
270 /* memdup_user allocates with GFP_KERNEL, so DMA is ok */
271 msgs[i].flags |= I2C_M_DMA_SAFE;
274 * If the message length is received from the slave (similar
275 * to SMBus block read), we must ensure that the buffer will
276 * be large enough to cope with a message length of
277 * I2C_SMBUS_BLOCK_MAX as this is the maximum underlying bus
278 * drivers allow. The first byte in the buffer must be
279 * pre-filled with the number of extra bytes, which must be
280 * at least one to hold the message length, but can be
281 * greater (for example to account for a checksum byte at
282 * the end of the message.)
284 if (msgs[i].flags & I2C_M_RECV_LEN) {
285 if (!(msgs[i].flags & I2C_M_RD) ||
286 msgs[i].len < 1 || msgs[i].buf[0] < 1 ||
287 msgs[i].len < msgs[i].buf[0] +
288 I2C_SMBUS_BLOCK_MAX) {
294 msgs[i].len = msgs[i].buf[0];
299 for (j = 0; j < i; ++j)
306 res = i2c_transfer(client->adapter, msgs, nmsgs);
308 if (res >= 0 && (msgs[i].flags & I2C_M_RD)) {
309 if (copy_to_user(data_ptrs[i], msgs[i].buf,
320 static noinline int i2cdev_ioctl_smbus(struct i2c_client *client,
321 u8 read_write, u8 command, u32 size,
322 union i2c_smbus_data __user *data)
324 union i2c_smbus_data temp = {};
327 if ((size != I2C_SMBUS_BYTE) &&
328 (size != I2C_SMBUS_QUICK) &&
329 (size != I2C_SMBUS_BYTE_DATA) &&
330 (size != I2C_SMBUS_WORD_DATA) &&
331 (size != I2C_SMBUS_PROC_CALL) &&
332 (size != I2C_SMBUS_BLOCK_DATA) &&
333 (size != I2C_SMBUS_I2C_BLOCK_BROKEN) &&
334 (size != I2C_SMBUS_I2C_BLOCK_DATA) &&
335 (size != I2C_SMBUS_BLOCK_PROC_CALL)) {
336 dev_dbg(&client->adapter->dev,
337 "size out of range (%x) in ioctl I2C_SMBUS.\n",
341 /* Note that I2C_SMBUS_READ and I2C_SMBUS_WRITE are 0 and 1,
342 so the check is valid if size==I2C_SMBUS_QUICK too. */
343 if ((read_write != I2C_SMBUS_READ) &&
344 (read_write != I2C_SMBUS_WRITE)) {
345 dev_dbg(&client->adapter->dev,
346 "read_write out of range (%x) in ioctl I2C_SMBUS.\n",
351 /* Note that command values are always valid! */
353 if ((size == I2C_SMBUS_QUICK) ||
354 ((size == I2C_SMBUS_BYTE) &&
355 (read_write == I2C_SMBUS_WRITE)))
356 /* These are special: we do not use data */
357 return i2c_smbus_xfer(client->adapter, client->addr,
358 client->flags, read_write,
359 command, size, NULL);
362 dev_dbg(&client->adapter->dev,
363 "data is NULL pointer in ioctl I2C_SMBUS.\n");
367 if ((size == I2C_SMBUS_BYTE_DATA) ||
368 (size == I2C_SMBUS_BYTE))
369 datasize = sizeof(data->byte);
370 else if ((size == I2C_SMBUS_WORD_DATA) ||
371 (size == I2C_SMBUS_PROC_CALL))
372 datasize = sizeof(data->word);
373 else /* size == smbus block, i2c block, or block proc. call */
374 datasize = sizeof(data->block);
376 if ((size == I2C_SMBUS_PROC_CALL) ||
377 (size == I2C_SMBUS_BLOCK_PROC_CALL) ||
378 (size == I2C_SMBUS_I2C_BLOCK_DATA) ||
379 (read_write == I2C_SMBUS_WRITE)) {
380 if (copy_from_user(&temp, data, datasize))
383 if (size == I2C_SMBUS_I2C_BLOCK_BROKEN) {
384 /* Convert old I2C block commands to the new
385 convention. This preserves binary compatibility. */
386 size = I2C_SMBUS_I2C_BLOCK_DATA;
387 if (read_write == I2C_SMBUS_READ)
388 temp.block[0] = I2C_SMBUS_BLOCK_MAX;
390 res = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
391 read_write, command, size, &temp);
392 if (!res && ((size == I2C_SMBUS_PROC_CALL) ||
393 (size == I2C_SMBUS_BLOCK_PROC_CALL) ||
394 (read_write == I2C_SMBUS_READ))) {
395 if (copy_to_user(data, &temp, datasize))
401 static long i2cdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
403 struct i2c_client *client = file->private_data;
406 dev_dbg(&client->adapter->dev, "ioctl, cmd=0x%02x, arg=0x%02lx\n",
411 case I2C_SLAVE_FORCE:
413 (((client->flags & I2C_M_TEN) == 0) && arg > 0x7f))
415 if (cmd == I2C_SLAVE && i2cdev_check_addr(client->adapter, arg))
417 /* REVISIT: address could become busy later */
422 client->flags |= I2C_M_TEN;
424 client->flags &= ~I2C_M_TEN;
428 * Setting the PEC flag here won't affect kernel drivers,
429 * which will be using the i2c_client node registered with
430 * the driver model core. Likewise, when that client has
431 * the PEC flag already set, the i2c-dev driver won't see
432 * (or use) this setting.
435 client->flags |= I2C_CLIENT_PEC;
437 client->flags &= ~I2C_CLIENT_PEC;
440 funcs = i2c_get_functionality(client->adapter);
441 return put_user(funcs, (unsigned long __user *)arg);
444 struct i2c_rdwr_ioctl_data rdwr_arg;
445 struct i2c_msg *rdwr_pa;
447 if (copy_from_user(&rdwr_arg,
448 (struct i2c_rdwr_ioctl_data __user *)arg,
452 if (!rdwr_arg.msgs || rdwr_arg.nmsgs == 0)
456 * Put an arbitrary limit on the number of messages that can
459 if (rdwr_arg.nmsgs > I2C_RDWR_IOCTL_MAX_MSGS)
462 rdwr_pa = memdup_user(rdwr_arg.msgs,
463 rdwr_arg.nmsgs * sizeof(struct i2c_msg));
465 return PTR_ERR(rdwr_pa);
467 return i2cdev_ioctl_rdwr(client, rdwr_arg.nmsgs, rdwr_pa);
471 struct i2c_smbus_ioctl_data data_arg;
472 if (copy_from_user(&data_arg,
473 (struct i2c_smbus_ioctl_data __user *) arg,
474 sizeof(struct i2c_smbus_ioctl_data)))
476 return i2cdev_ioctl_smbus(client, data_arg.read_write,
485 client->adapter->retries = arg;
491 /* For historical reasons, user-space sets the timeout
492 * value in units of 10 ms.
494 client->adapter->timeout = msecs_to_jiffies(arg * 10);
497 /* NOTE: returning a fault code here could cause trouble
498 * in buggy userspace code. Some old kernel bugs returned
499 * zero in this case, and userspace code might accidentally
500 * have depended on that bug.
509 struct i2c_smbus_ioctl_data32 {
513 compat_caddr_t data; /* union i2c_smbus_data *data */
523 struct i2c_rdwr_ioctl_data32 {
524 compat_caddr_t msgs; /* struct i2c_msg __user *msgs */
528 static long compat_i2cdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
530 struct i2c_client *client = file->private_data;
534 funcs = i2c_get_functionality(client->adapter);
535 return put_user(funcs, (compat_ulong_t __user *)arg);
537 struct i2c_rdwr_ioctl_data32 rdwr_arg;
539 struct i2c_msg *rdwr_pa;
542 if (copy_from_user(&rdwr_arg,
543 (struct i2c_rdwr_ioctl_data32 __user *)arg,
547 if (!rdwr_arg.msgs || rdwr_arg.nmsgs == 0)
550 if (rdwr_arg.nmsgs > I2C_RDWR_IOCTL_MAX_MSGS)
553 rdwr_pa = kmalloc_array(rdwr_arg.nmsgs, sizeof(struct i2c_msg),
558 p = compat_ptr(rdwr_arg.msgs);
559 for (i = 0; i < rdwr_arg.nmsgs; i++) {
560 struct i2c_msg32 umsg;
561 if (copy_from_user(&umsg, p + i, sizeof(umsg))) {
565 rdwr_pa[i] = (struct i2c_msg) {
569 .buf = compat_ptr(umsg.buf)
573 return i2cdev_ioctl_rdwr(client, rdwr_arg.nmsgs, rdwr_pa);
576 struct i2c_smbus_ioctl_data32 data32;
577 if (copy_from_user(&data32,
581 return i2cdev_ioctl_smbus(client, data32.read_write,
584 compat_ptr(data32.data));
587 return i2cdev_ioctl(file, cmd, arg);
591 #define compat_i2cdev_ioctl NULL
594 static int i2cdev_open(struct inode *inode, struct file *file)
596 unsigned int minor = iminor(inode);
597 struct i2c_client *client;
598 struct i2c_adapter *adap;
600 adap = i2c_get_adapter(minor);
604 /* This creates an anonymous i2c_client, which may later be
605 * pointed to some address using I2C_SLAVE or I2C_SLAVE_FORCE.
607 * This client is ** NEVER REGISTERED ** with the driver model
608 * or I2C core code!! It just holds private copies of addressing
609 * information and maybe a PEC flag.
611 client = kzalloc(sizeof(*client), GFP_KERNEL);
613 i2c_put_adapter(adap);
616 snprintf(client->name, I2C_NAME_SIZE, "i2c-dev %d", adap->nr);
618 client->adapter = adap;
619 file->private_data = client;
624 static int i2cdev_release(struct inode *inode, struct file *file)
626 struct i2c_client *client = file->private_data;
628 i2c_put_adapter(client->adapter);
630 file->private_data = NULL;
635 static const struct file_operations i2cdev_fops = {
636 .owner = THIS_MODULE,
639 .write = i2cdev_write,
640 .unlocked_ioctl = i2cdev_ioctl,
641 .compat_ioctl = compat_i2cdev_ioctl,
643 .release = i2cdev_release,
646 /* ------------------------------------------------------------------------- */
648 static struct class *i2c_dev_class;
650 static void i2cdev_dev_release(struct device *dev)
652 struct i2c_dev *i2c_dev;
654 i2c_dev = container_of(dev, struct i2c_dev, dev);
658 static int i2cdev_attach_adapter(struct device *dev, void *dummy)
660 struct i2c_adapter *adap;
661 struct i2c_dev *i2c_dev;
664 if (dev->type != &i2c_adapter_type)
666 adap = to_i2c_adapter(dev);
668 i2c_dev = get_free_i2c_dev(adap);
670 return PTR_ERR(i2c_dev);
672 cdev_init(&i2c_dev->cdev, &i2cdev_fops);
673 i2c_dev->cdev.owner = THIS_MODULE;
675 device_initialize(&i2c_dev->dev);
676 i2c_dev->dev.devt = MKDEV(I2C_MAJOR, adap->nr);
677 i2c_dev->dev.class = i2c_dev_class;
678 i2c_dev->dev.parent = &adap->dev;
679 i2c_dev->dev.release = i2cdev_dev_release;
680 dev_set_name(&i2c_dev->dev, "i2c-%d", adap->nr);
682 res = cdev_device_add(&i2c_dev->cdev, &i2c_dev->dev);
684 put_i2c_dev(i2c_dev, false);
688 pr_debug("i2c-dev: adapter [%s] registered as minor %d\n",
689 adap->name, adap->nr);
693 static int i2cdev_detach_adapter(struct device *dev, void *dummy)
695 struct i2c_adapter *adap;
696 struct i2c_dev *i2c_dev;
698 if (dev->type != &i2c_adapter_type)
700 adap = to_i2c_adapter(dev);
702 i2c_dev = i2c_dev_get_by_minor(adap->nr);
703 if (!i2c_dev) /* attach_adapter must have failed */
706 put_i2c_dev(i2c_dev, true);
708 pr_debug("i2c-dev: adapter [%s] unregistered\n", adap->name);
712 static int i2cdev_notifier_call(struct notifier_block *nb, unsigned long action,
715 struct device *dev = data;
718 case BUS_NOTIFY_ADD_DEVICE:
719 return i2cdev_attach_adapter(dev, NULL);
720 case BUS_NOTIFY_DEL_DEVICE:
721 return i2cdev_detach_adapter(dev, NULL);
727 static struct notifier_block i2cdev_notifier = {
728 .notifier_call = i2cdev_notifier_call,
731 /* ------------------------------------------------------------------------- */
734 * module load/unload record keeping
737 static int __init i2c_dev_init(void)
741 printk(KERN_INFO "i2c /dev entries driver\n");
743 res = register_chrdev_region(MKDEV(I2C_MAJOR, 0), I2C_MINORS, "i2c");
747 i2c_dev_class = class_create(THIS_MODULE, "i2c-dev");
748 if (IS_ERR(i2c_dev_class)) {
749 res = PTR_ERR(i2c_dev_class);
750 goto out_unreg_chrdev;
752 i2c_dev_class->dev_groups = i2c_groups;
754 /* Keep track of adapters which will be added or removed later */
755 res = bus_register_notifier(&i2c_bus_type, &i2cdev_notifier);
757 goto out_unreg_class;
759 /* Bind to already existing adapters right away */
760 i2c_for_each_dev(NULL, i2cdev_attach_adapter);
765 class_destroy(i2c_dev_class);
767 unregister_chrdev_region(MKDEV(I2C_MAJOR, 0), I2C_MINORS);
769 printk(KERN_ERR "%s: Driver Initialisation failed\n", __FILE__);
773 static void __exit i2c_dev_exit(void)
775 bus_unregister_notifier(&i2c_bus_type, &i2cdev_notifier);
776 i2c_for_each_dev(NULL, i2cdev_detach_adapter);
777 class_destroy(i2c_dev_class);
778 unregister_chrdev_region(MKDEV(I2C_MAJOR, 0), I2C_MINORS);
781 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and "
782 "Simon G. Vogl <simon@tk.uni-linz.ac.at>");
783 MODULE_DESCRIPTION("I2C /dev entries driver");
784 MODULE_LICENSE("GPL");
786 module_init(i2c_dev_init);
787 module_exit(i2c_dev_exit);