1 /* 2 i2c-dev.c - i2c-bus driver, char device interface 3 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> 7 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. 12 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. 17 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. 21 */ 22 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 */ 26 27 /* The I2C_RDWR ioctl code is written by Kolja Waschk <waschk@telos.de> */ 28 29 #include <linux/kernel.h> 30 #include <linux/module.h> 31 #include <linux/fs.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> 38 39 static struct i2c_driver i2cdev_driver; 40 41 /* 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. 45 * 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. 49 */ 50 struct i2c_dev { 51 struct list_head list; 52 struct i2c_adapter *adap; 53 struct device *dev; 54 }; 55 56 #define I2C_MINORS 256 57 static LIST_HEAD(i2c_dev_list); 58 static DEFINE_SPINLOCK(i2c_dev_list_lock); 59 60 static struct i2c_dev *i2c_dev_get_by_minor(unsigned index) 61 { 62 struct i2c_dev *i2c_dev; 63 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) 67 goto found; 68 } 69 i2c_dev = NULL; 70 found: 71 spin_unlock(&i2c_dev_list_lock); 72 return i2c_dev; 73 } 74 75 static struct i2c_dev *get_free_i2c_dev(struct i2c_adapter *adap) 76 { 77 struct i2c_dev *i2c_dev; 78 79 if (adap->nr >= I2C_MINORS) { 80 printk(KERN_ERR "i2c-dev: Out of device minors (%d)\n", 81 adap->nr); 82 return ERR_PTR(-ENODEV); 83 } 84 85 i2c_dev = kzalloc(sizeof(*i2c_dev), GFP_KERNEL); 86 if (!i2c_dev) 87 return ERR_PTR(-ENOMEM); 88 i2c_dev->adap = adap; 89 90 spin_lock(&i2c_dev_list_lock); 91 list_add_tail(&i2c_dev->list, &i2c_dev_list); 92 spin_unlock(&i2c_dev_list_lock); 93 return i2c_dev; 94 } 95 96 static void return_i2c_dev(struct i2c_dev *i2c_dev) 97 { 98 spin_lock(&i2c_dev_list_lock); 99 list_del(&i2c_dev->list); 100 spin_unlock(&i2c_dev_list_lock); 101 kfree(i2c_dev); 102 } 103 104 static ssize_t show_adapter_name(struct device *dev, 105 struct device_attribute *attr, char *buf) 106 { 107 struct i2c_dev *i2c_dev = i2c_dev_get_by_minor(MINOR(dev->devt)); 108 109 if (!i2c_dev) 110 return -ENODEV; 111 return sprintf(buf, "%s\n", i2c_dev->adap->name); 112 } 113 static DEVICE_ATTR(name, S_IRUGO, show_adapter_name, NULL); 114 115 /* ------------------------------------------------------------------------- */ 116 117 /* 118 * After opening an instance of this character special file, a file 119 * descriptor starts out associated only with an i2c_adapter (and bus). 120 * 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. 126 * 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. 132 */ 133 134 static ssize_t i2cdev_read (struct file *file, char __user *buf, size_t count, 135 loff_t *offset) 136 { 137 char *tmp; 138 int ret; 139 140 struct i2c_client *client = (struct i2c_client *)file->private_data; 141 142 if (count > 8192) 143 count = 8192; 144 145 tmp = kmalloc(count,GFP_KERNEL); 146 if (tmp==NULL) 147 return -ENOMEM; 148 149 pr_debug("i2c-dev: i2c-%d reading %zd bytes.\n", 150 iminor(file->f_path.dentry->d_inode), count); 151 152 ret = i2c_master_recv(client,tmp,count); 153 if (ret >= 0) 154 ret = copy_to_user(buf,tmp,count)?-EFAULT:ret; 155 kfree(tmp); 156 return ret; 157 } 158 159 static ssize_t i2cdev_write (struct file *file, const char __user *buf, size_t count, 160 loff_t *offset) 161 { 162 int ret; 163 char *tmp; 164 struct i2c_client *client = (struct i2c_client *)file->private_data; 165 166 if (count > 8192) 167 count = 8192; 168 169 tmp = kmalloc(count,GFP_KERNEL); 170 if (tmp==NULL) 171 return -ENOMEM; 172 if (copy_from_user(tmp,buf,count)) { 173 kfree(tmp); 174 return -EFAULT; 175 } 176 177 pr_debug("i2c-dev: i2c-%d writing %zd bytes.\n", 178 iminor(file->f_path.dentry->d_inode), count); 179 180 ret = i2c_master_send(client,tmp,count); 181 kfree(tmp); 182 return ret; 183 } 184 185 static int i2cdev_check(struct device *dev, void *addrp) 186 { 187 struct i2c_client *client = i2c_verify_client(dev); 188 189 if (!client || client->addr != *(unsigned int *)addrp) 190 return 0; 191 192 return dev->driver ? -EBUSY : 0; 193 } 194 195 /* This address checking function differs from the one in i2c-core 196 in that it considers an address with a registered device, but no 197 driver bound to it, as NOT busy. */ 198 static int i2cdev_check_addr(struct i2c_adapter *adapter, unsigned int addr) 199 { 200 return device_for_each_child(&adapter->dev, &addr, i2cdev_check); 201 } 202 203 static noinline int i2cdev_ioctl_rdrw(struct i2c_client *client, 204 unsigned long arg) 205 { 206 struct i2c_rdwr_ioctl_data rdwr_arg; 207 struct i2c_msg *rdwr_pa; 208 u8 __user **data_ptrs; 209 int i, res; 210 211 if (copy_from_user(&rdwr_arg, 212 (struct i2c_rdwr_ioctl_data __user *)arg, 213 sizeof(rdwr_arg))) 214 return -EFAULT; 215 216 /* Put an arbitrary limit on the number of messages that can 217 * be sent at once */ 218 if (rdwr_arg.nmsgs > I2C_RDRW_IOCTL_MAX_MSGS) 219 return -EINVAL; 220 221 rdwr_pa = (struct i2c_msg *) 222 kmalloc(rdwr_arg.nmsgs * sizeof(struct i2c_msg), 223 GFP_KERNEL); 224 if (!rdwr_pa) 225 return -ENOMEM; 226 227 if (copy_from_user(rdwr_pa, rdwr_arg.msgs, 228 rdwr_arg.nmsgs * sizeof(struct i2c_msg))) { 229 kfree(rdwr_pa); 230 return -EFAULT; 231 } 232 233 data_ptrs = kmalloc(rdwr_arg.nmsgs * sizeof(u8 __user *), GFP_KERNEL); 234 if (data_ptrs == NULL) { 235 kfree(rdwr_pa); 236 return -ENOMEM; 237 } 238 239 res = 0; 240 for (i = 0; i < rdwr_arg.nmsgs; i++) { 241 /* Limit the size of the message to a sane amount; 242 * and don't let length change either. */ 243 if ((rdwr_pa[i].len > 8192) || 244 (rdwr_pa[i].flags & I2C_M_RECV_LEN)) { 245 res = -EINVAL; 246 break; 247 } 248 data_ptrs[i] = (u8 __user *)rdwr_pa[i].buf; 249 rdwr_pa[i].buf = kmalloc(rdwr_pa[i].len, GFP_KERNEL); 250 if (rdwr_pa[i].buf == NULL) { 251 res = -ENOMEM; 252 break; 253 } 254 if (copy_from_user(rdwr_pa[i].buf, data_ptrs[i], 255 rdwr_pa[i].len)) { 256 ++i; /* Needs to be kfreed too */ 257 res = -EFAULT; 258 break; 259 } 260 } 261 if (res < 0) { 262 int j; 263 for (j = 0; j < i; ++j) 264 kfree(rdwr_pa[j].buf); 265 kfree(data_ptrs); 266 kfree(rdwr_pa); 267 return res; 268 } 269 270 res = i2c_transfer(client->adapter, rdwr_pa, rdwr_arg.nmsgs); 271 while (i-- > 0) { 272 if (res >= 0 && (rdwr_pa[i].flags & I2C_M_RD)) { 273 if (copy_to_user(data_ptrs[i], rdwr_pa[i].buf, 274 rdwr_pa[i].len)) 275 res = -EFAULT; 276 } 277 kfree(rdwr_pa[i].buf); 278 } 279 kfree(data_ptrs); 280 kfree(rdwr_pa); 281 return res; 282 } 283 284 static noinline int i2cdev_ioctl_smbus(struct i2c_client *client, 285 unsigned long arg) 286 { 287 struct i2c_smbus_ioctl_data data_arg; 288 union i2c_smbus_data temp; 289 int datasize, res; 290 291 if (copy_from_user(&data_arg, 292 (struct i2c_smbus_ioctl_data __user *) arg, 293 sizeof(struct i2c_smbus_ioctl_data))) 294 return -EFAULT; 295 if ((data_arg.size != I2C_SMBUS_BYTE) && 296 (data_arg.size != I2C_SMBUS_QUICK) && 297 (data_arg.size != I2C_SMBUS_BYTE_DATA) && 298 (data_arg.size != I2C_SMBUS_WORD_DATA) && 299 (data_arg.size != I2C_SMBUS_PROC_CALL) && 300 (data_arg.size != I2C_SMBUS_BLOCK_DATA) && 301 (data_arg.size != I2C_SMBUS_I2C_BLOCK_BROKEN) && 302 (data_arg.size != I2C_SMBUS_I2C_BLOCK_DATA) && 303 (data_arg.size != I2C_SMBUS_BLOCK_PROC_CALL)) { 304 dev_dbg(&client->adapter->dev, 305 "size out of range (%x) in ioctl I2C_SMBUS.\n", 306 data_arg.size); 307 return -EINVAL; 308 } 309 /* Note that I2C_SMBUS_READ and I2C_SMBUS_WRITE are 0 and 1, 310 so the check is valid if size==I2C_SMBUS_QUICK too. */ 311 if ((data_arg.read_write != I2C_SMBUS_READ) && 312 (data_arg.read_write != I2C_SMBUS_WRITE)) { 313 dev_dbg(&client->adapter->dev, 314 "read_write out of range (%x) in ioctl I2C_SMBUS.\n", 315 data_arg.read_write); 316 return -EINVAL; 317 } 318 319 /* Note that command values are always valid! */ 320 321 if ((data_arg.size == I2C_SMBUS_QUICK) || 322 ((data_arg.size == I2C_SMBUS_BYTE) && 323 (data_arg.read_write == I2C_SMBUS_WRITE))) 324 /* These are special: we do not use data */ 325 return i2c_smbus_xfer(client->adapter, client->addr, 326 client->flags, data_arg.read_write, 327 data_arg.command, data_arg.size, NULL); 328 329 if (data_arg.data == NULL) { 330 dev_dbg(&client->adapter->dev, 331 "data is NULL pointer in ioctl I2C_SMBUS.\n"); 332 return -EINVAL; 333 } 334 335 if ((data_arg.size == I2C_SMBUS_BYTE_DATA) || 336 (data_arg.size == I2C_SMBUS_BYTE)) 337 datasize = sizeof(data_arg.data->byte); 338 else if ((data_arg.size == I2C_SMBUS_WORD_DATA) || 339 (data_arg.size == I2C_SMBUS_PROC_CALL)) 340 datasize = sizeof(data_arg.data->word); 341 else /* size == smbus block, i2c block, or block proc. call */ 342 datasize = sizeof(data_arg.data->block); 343 344 if ((data_arg.size == I2C_SMBUS_PROC_CALL) || 345 (data_arg.size == I2C_SMBUS_BLOCK_PROC_CALL) || 346 (data_arg.size == I2C_SMBUS_I2C_BLOCK_DATA) || 347 (data_arg.read_write == I2C_SMBUS_WRITE)) { 348 if (copy_from_user(&temp, data_arg.data, datasize)) 349 return -EFAULT; 350 } 351 if (data_arg.size == I2C_SMBUS_I2C_BLOCK_BROKEN) { 352 /* Convert old I2C block commands to the new 353 convention. This preserves binary compatibility. */ 354 data_arg.size = I2C_SMBUS_I2C_BLOCK_DATA; 355 if (data_arg.read_write == I2C_SMBUS_READ) 356 temp.block[0] = I2C_SMBUS_BLOCK_MAX; 357 } 358 res = i2c_smbus_xfer(client->adapter, client->addr, client->flags, 359 data_arg.read_write, data_arg.command, data_arg.size, &temp); 360 if (!res && ((data_arg.size == I2C_SMBUS_PROC_CALL) || 361 (data_arg.size == I2C_SMBUS_BLOCK_PROC_CALL) || 362 (data_arg.read_write == I2C_SMBUS_READ))) { 363 if (copy_to_user(data_arg.data, &temp, datasize)) 364 return -EFAULT; 365 } 366 return res; 367 } 368 369 static int i2cdev_ioctl(struct inode *inode, struct file *file, 370 unsigned int cmd, unsigned long arg) 371 { 372 struct i2c_client *client = (struct i2c_client *)file->private_data; 373 unsigned long funcs; 374 375 dev_dbg(&client->adapter->dev, "ioctl, cmd=0x%02x, arg=0x%02lx\n", 376 cmd, arg); 377 378 switch ( cmd ) { 379 case I2C_SLAVE: 380 case I2C_SLAVE_FORCE: 381 /* NOTE: devices set up to work with "new style" drivers 382 * can't use I2C_SLAVE, even when the device node is not 383 * bound to a driver. Only I2C_SLAVE_FORCE will work. 384 * 385 * Setting the PEC flag here won't affect kernel drivers, 386 * which will be using the i2c_client node registered with 387 * the driver model core. Likewise, when that client has 388 * the PEC flag already set, the i2c-dev driver won't see 389 * (or use) this setting. 390 */ 391 if ((arg > 0x3ff) || 392 (((client->flags & I2C_M_TEN) == 0) && arg > 0x7f)) 393 return -EINVAL; 394 if (cmd == I2C_SLAVE && i2cdev_check_addr(client->adapter, arg)) 395 return -EBUSY; 396 /* REVISIT: address could become busy later */ 397 client->addr = arg; 398 return 0; 399 case I2C_TENBIT: 400 if (arg) 401 client->flags |= I2C_M_TEN; 402 else 403 client->flags &= ~I2C_M_TEN; 404 return 0; 405 case I2C_PEC: 406 if (arg) 407 client->flags |= I2C_CLIENT_PEC; 408 else 409 client->flags &= ~I2C_CLIENT_PEC; 410 return 0; 411 case I2C_FUNCS: 412 funcs = i2c_get_functionality(client->adapter); 413 return put_user(funcs, (unsigned long __user *)arg); 414 415 case I2C_RDWR: 416 return i2cdev_ioctl_rdrw(client, arg); 417 418 case I2C_SMBUS: 419 return i2cdev_ioctl_smbus(client, arg); 420 421 case I2C_RETRIES: 422 client->adapter->retries = arg; 423 break; 424 case I2C_TIMEOUT: 425 client->adapter->timeout = arg; 426 break; 427 default: 428 /* NOTE: returning a fault code here could cause trouble 429 * in buggy userspace code. Some old kernel bugs returned 430 * zero in this case, and userspace code might accidentally 431 * have depended on that bug. 432 */ 433 return -ENOTTY; 434 } 435 return 0; 436 } 437 438 static int i2cdev_open(struct inode *inode, struct file *file) 439 { 440 unsigned int minor = iminor(inode); 441 struct i2c_client *client; 442 struct i2c_adapter *adap; 443 struct i2c_dev *i2c_dev; 444 445 i2c_dev = i2c_dev_get_by_minor(minor); 446 if (!i2c_dev) 447 return -ENODEV; 448 449 adap = i2c_get_adapter(i2c_dev->adap->nr); 450 if (!adap) 451 return -ENODEV; 452 453 /* This creates an anonymous i2c_client, which may later be 454 * pointed to some address using I2C_SLAVE or I2C_SLAVE_FORCE. 455 * 456 * This client is ** NEVER REGISTERED ** with the driver model 457 * or I2C core code!! It just holds private copies of addressing 458 * information and maybe a PEC flag. 459 */ 460 client = kzalloc(sizeof(*client), GFP_KERNEL); 461 if (!client) { 462 i2c_put_adapter(adap); 463 return -ENOMEM; 464 } 465 snprintf(client->name, I2C_NAME_SIZE, "i2c-dev %d", adap->nr); 466 client->driver = &i2cdev_driver; 467 468 client->adapter = adap; 469 file->private_data = client; 470 471 return 0; 472 } 473 474 static int i2cdev_release(struct inode *inode, struct file *file) 475 { 476 struct i2c_client *client = file->private_data; 477 478 i2c_put_adapter(client->adapter); 479 kfree(client); 480 file->private_data = NULL; 481 482 return 0; 483 } 484 485 static const struct file_operations i2cdev_fops = { 486 .owner = THIS_MODULE, 487 .llseek = no_llseek, 488 .read = i2cdev_read, 489 .write = i2cdev_write, 490 .ioctl = i2cdev_ioctl, 491 .open = i2cdev_open, 492 .release = i2cdev_release, 493 }; 494 495 /* ------------------------------------------------------------------------- */ 496 497 /* 498 * The legacy "i2cdev_driver" is used primarily to get notifications when 499 * I2C adapters are added or removed, so that each one gets an i2c_dev 500 * and is thus made available to userspace driver code. 501 */ 502 503 static struct class *i2c_dev_class; 504 505 static int i2cdev_attach_adapter(struct i2c_adapter *adap) 506 { 507 struct i2c_dev *i2c_dev; 508 int res; 509 510 i2c_dev = get_free_i2c_dev(adap); 511 if (IS_ERR(i2c_dev)) 512 return PTR_ERR(i2c_dev); 513 514 /* register this i2c device with the driver core */ 515 i2c_dev->dev = device_create(i2c_dev_class, &adap->dev, 516 MKDEV(I2C_MAJOR, adap->nr), 517 "i2c-%d", adap->nr); 518 if (IS_ERR(i2c_dev->dev)) { 519 res = PTR_ERR(i2c_dev->dev); 520 goto error; 521 } 522 res = device_create_file(i2c_dev->dev, &dev_attr_name); 523 if (res) 524 goto error_destroy; 525 526 pr_debug("i2c-dev: adapter [%s] registered as minor %d\n", 527 adap->name, adap->nr); 528 return 0; 529 error_destroy: 530 device_destroy(i2c_dev_class, MKDEV(I2C_MAJOR, adap->nr)); 531 error: 532 return_i2c_dev(i2c_dev); 533 return res; 534 } 535 536 static int i2cdev_detach_adapter(struct i2c_adapter *adap) 537 { 538 struct i2c_dev *i2c_dev; 539 540 i2c_dev = i2c_dev_get_by_minor(adap->nr); 541 if (!i2c_dev) /* attach_adapter must have failed */ 542 return 0; 543 544 device_remove_file(i2c_dev->dev, &dev_attr_name); 545 return_i2c_dev(i2c_dev); 546 device_destroy(i2c_dev_class, MKDEV(I2C_MAJOR, adap->nr)); 547 548 pr_debug("i2c-dev: adapter [%s] unregistered\n", adap->name); 549 return 0; 550 } 551 552 static int i2cdev_detach_client(struct i2c_client *client) 553 { 554 return 0; 555 } 556 557 static struct i2c_driver i2cdev_driver = { 558 .driver = { 559 .name = "dev_driver", 560 }, 561 .id = I2C_DRIVERID_I2CDEV, 562 .attach_adapter = i2cdev_attach_adapter, 563 .detach_adapter = i2cdev_detach_adapter, 564 .detach_client = i2cdev_detach_client, 565 }; 566 567 /* ------------------------------------------------------------------------- */ 568 569 /* 570 * module load/unload record keeping 571 */ 572 573 static int __init i2c_dev_init(void) 574 { 575 int res; 576 577 printk(KERN_INFO "i2c /dev entries driver\n"); 578 579 res = register_chrdev(I2C_MAJOR, "i2c", &i2cdev_fops); 580 if (res) 581 goto out; 582 583 i2c_dev_class = class_create(THIS_MODULE, "i2c-dev"); 584 if (IS_ERR(i2c_dev_class)) 585 goto out_unreg_chrdev; 586 587 res = i2c_add_driver(&i2cdev_driver); 588 if (res) 589 goto out_unreg_class; 590 591 return 0; 592 593 out_unreg_class: 594 class_destroy(i2c_dev_class); 595 out_unreg_chrdev: 596 unregister_chrdev(I2C_MAJOR, "i2c"); 597 out: 598 printk(KERN_ERR "%s: Driver Initialisation failed\n", __FILE__); 599 return res; 600 } 601 602 static void __exit i2c_dev_exit(void) 603 { 604 i2c_del_driver(&i2cdev_driver); 605 class_destroy(i2c_dev_class); 606 unregister_chrdev(I2C_MAJOR,"i2c"); 607 } 608 609 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and " 610 "Simon G. Vogl <simon@tk.uni-linz.ac.at>"); 611 MODULE_DESCRIPTION("I2C /dev entries driver"); 612 MODULE_LICENSE("GPL"); 613 614 module_init(i2c_dev_init); 615 module_exit(i2c_dev_exit); 616