1 /* 2 * Simple synchronous userspace interface to SPI devices 3 * 4 * Copyright (C) 2006 SWAPP 5 * Andrea Paterniani <a.paterniani@swapp-eng.it> 6 * Copyright (C) 2007 David Brownell (simplification, cleanup) 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 19 #include <linux/init.h> 20 #include <linux/module.h> 21 #include <linux/ioctl.h> 22 #include <linux/fs.h> 23 #include <linux/device.h> 24 #include <linux/err.h> 25 #include <linux/list.h> 26 #include <linux/errno.h> 27 #include <linux/mutex.h> 28 #include <linux/slab.h> 29 #include <linux/compat.h> 30 #include <linux/of.h> 31 #include <linux/of_device.h> 32 33 #include <linux/spi/spi.h> 34 #include <linux/spi/spidev.h> 35 36 #include <linux/uaccess.h> 37 38 39 /* 40 * This supports access to SPI devices using normal userspace I/O calls. 41 * Note that while traditional UNIX/POSIX I/O semantics are half duplex, 42 * and often mask message boundaries, full SPI support requires full duplex 43 * transfers. There are several kinds of internal message boundaries to 44 * handle chipselect management and other protocol options. 45 * 46 * SPI has a character major number assigned. We allocate minor numbers 47 * dynamically using a bitmask. You must use hotplug tools, such as udev 48 * (or mdev with busybox) to create and destroy the /dev/spidevB.C device 49 * nodes, since there is no fixed association of minor numbers with any 50 * particular SPI bus or device. 51 */ 52 #define SPIDEV_MAJOR 153 /* assigned */ 53 #define N_SPI_MINORS 32 /* ... up to 256 */ 54 55 static DECLARE_BITMAP(minors, N_SPI_MINORS); 56 57 58 /* Bit masks for spi_device.mode management. Note that incorrect 59 * settings for some settings can cause *lots* of trouble for other 60 * devices on a shared bus: 61 * 62 * - CS_HIGH ... this device will be active when it shouldn't be 63 * - 3WIRE ... when active, it won't behave as it should 64 * - NO_CS ... there will be no explicit message boundaries; this 65 * is completely incompatible with the shared bus model 66 * - READY ... transfers may proceed when they shouldn't. 67 * 68 * REVISIT should changing those flags be privileged? 69 */ 70 #define SPI_MODE_MASK (SPI_CPHA | SPI_CPOL | SPI_CS_HIGH \ 71 | SPI_LSB_FIRST | SPI_3WIRE | SPI_LOOP \ 72 | SPI_NO_CS | SPI_READY | SPI_TX_DUAL \ 73 | SPI_TX_QUAD | SPI_RX_DUAL | SPI_RX_QUAD) 74 75 struct spidev_data { 76 dev_t devt; 77 spinlock_t spi_lock; 78 struct spi_device *spi; 79 struct list_head device_entry; 80 81 /* TX/RX buffers are NULL unless this device is open (users > 0) */ 82 struct mutex buf_lock; 83 unsigned users; 84 u8 *tx_buffer; 85 u8 *rx_buffer; 86 u32 speed_hz; 87 }; 88 89 static LIST_HEAD(device_list); 90 static DEFINE_MUTEX(device_list_lock); 91 92 static unsigned bufsiz = 4096; 93 module_param(bufsiz, uint, S_IRUGO); 94 MODULE_PARM_DESC(bufsiz, "data bytes in biggest supported SPI message"); 95 96 /*-------------------------------------------------------------------------*/ 97 98 static ssize_t 99 spidev_sync(struct spidev_data *spidev, struct spi_message *message) 100 { 101 DECLARE_COMPLETION_ONSTACK(done); 102 int status; 103 struct spi_device *spi; 104 105 spin_lock_irq(&spidev->spi_lock); 106 spi = spidev->spi; 107 spin_unlock_irq(&spidev->spi_lock); 108 109 if (spi == NULL) 110 status = -ESHUTDOWN; 111 else 112 status = spi_sync(spi, message); 113 114 if (status == 0) 115 status = message->actual_length; 116 117 return status; 118 } 119 120 static inline ssize_t 121 spidev_sync_write(struct spidev_data *spidev, size_t len) 122 { 123 struct spi_transfer t = { 124 .tx_buf = spidev->tx_buffer, 125 .len = len, 126 .speed_hz = spidev->speed_hz, 127 }; 128 struct spi_message m; 129 130 spi_message_init(&m); 131 spi_message_add_tail(&t, &m); 132 return spidev_sync(spidev, &m); 133 } 134 135 static inline ssize_t 136 spidev_sync_read(struct spidev_data *spidev, size_t len) 137 { 138 struct spi_transfer t = { 139 .rx_buf = spidev->rx_buffer, 140 .len = len, 141 .speed_hz = spidev->speed_hz, 142 }; 143 struct spi_message m; 144 145 spi_message_init(&m); 146 spi_message_add_tail(&t, &m); 147 return spidev_sync(spidev, &m); 148 } 149 150 /*-------------------------------------------------------------------------*/ 151 152 /* Read-only message with current device setup */ 153 static ssize_t 154 spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos) 155 { 156 struct spidev_data *spidev; 157 ssize_t status = 0; 158 159 /* chipselect only toggles at start or end of operation */ 160 if (count > bufsiz) 161 return -EMSGSIZE; 162 163 spidev = filp->private_data; 164 165 mutex_lock(&spidev->buf_lock); 166 status = spidev_sync_read(spidev, count); 167 if (status > 0) { 168 unsigned long missing; 169 170 missing = copy_to_user(buf, spidev->rx_buffer, status); 171 if (missing == status) 172 status = -EFAULT; 173 else 174 status = status - missing; 175 } 176 mutex_unlock(&spidev->buf_lock); 177 178 return status; 179 } 180 181 /* Write-only message with current device setup */ 182 static ssize_t 183 spidev_write(struct file *filp, const char __user *buf, 184 size_t count, loff_t *f_pos) 185 { 186 struct spidev_data *spidev; 187 ssize_t status = 0; 188 unsigned long missing; 189 190 /* chipselect only toggles at start or end of operation */ 191 if (count > bufsiz) 192 return -EMSGSIZE; 193 194 spidev = filp->private_data; 195 196 mutex_lock(&spidev->buf_lock); 197 missing = copy_from_user(spidev->tx_buffer, buf, count); 198 if (missing == 0) 199 status = spidev_sync_write(spidev, count); 200 else 201 status = -EFAULT; 202 mutex_unlock(&spidev->buf_lock); 203 204 return status; 205 } 206 207 static int spidev_message(struct spidev_data *spidev, 208 struct spi_ioc_transfer *u_xfers, unsigned n_xfers) 209 { 210 struct spi_message msg; 211 struct spi_transfer *k_xfers; 212 struct spi_transfer *k_tmp; 213 struct spi_ioc_transfer *u_tmp; 214 unsigned n, total, tx_total, rx_total; 215 u8 *tx_buf, *rx_buf; 216 int status = -EFAULT; 217 218 spi_message_init(&msg); 219 k_xfers = kcalloc(n_xfers, sizeof(*k_tmp), GFP_KERNEL); 220 if (k_xfers == NULL) 221 return -ENOMEM; 222 223 /* Construct spi_message, copying any tx data to bounce buffer. 224 * We walk the array of user-provided transfers, using each one 225 * to initialize a kernel version of the same transfer. 226 */ 227 tx_buf = spidev->tx_buffer; 228 rx_buf = spidev->rx_buffer; 229 total = 0; 230 tx_total = 0; 231 rx_total = 0; 232 for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers; 233 n; 234 n--, k_tmp++, u_tmp++) { 235 k_tmp->len = u_tmp->len; 236 237 total += k_tmp->len; 238 /* Since the function returns the total length of transfers 239 * on success, restrict the total to positive int values to 240 * avoid the return value looking like an error. Also check 241 * each transfer length to avoid arithmetic overflow. 242 */ 243 if (total > INT_MAX || k_tmp->len > INT_MAX) { 244 status = -EMSGSIZE; 245 goto done; 246 } 247 248 if (u_tmp->rx_buf) { 249 /* this transfer needs space in RX bounce buffer */ 250 rx_total += k_tmp->len; 251 if (rx_total > bufsiz) { 252 status = -EMSGSIZE; 253 goto done; 254 } 255 k_tmp->rx_buf = rx_buf; 256 if (!access_ok(VERIFY_WRITE, (u8 __user *) 257 (uintptr_t) u_tmp->rx_buf, 258 u_tmp->len)) 259 goto done; 260 rx_buf += k_tmp->len; 261 } 262 if (u_tmp->tx_buf) { 263 /* this transfer needs space in TX bounce buffer */ 264 tx_total += k_tmp->len; 265 if (tx_total > bufsiz) { 266 status = -EMSGSIZE; 267 goto done; 268 } 269 k_tmp->tx_buf = tx_buf; 270 if (copy_from_user(tx_buf, (const u8 __user *) 271 (uintptr_t) u_tmp->tx_buf, 272 u_tmp->len)) 273 goto done; 274 tx_buf += k_tmp->len; 275 } 276 277 k_tmp->cs_change = !!u_tmp->cs_change; 278 k_tmp->tx_nbits = u_tmp->tx_nbits; 279 k_tmp->rx_nbits = u_tmp->rx_nbits; 280 k_tmp->bits_per_word = u_tmp->bits_per_word; 281 k_tmp->delay_usecs = u_tmp->delay_usecs; 282 k_tmp->speed_hz = u_tmp->speed_hz; 283 if (!k_tmp->speed_hz) 284 k_tmp->speed_hz = spidev->speed_hz; 285 #ifdef VERBOSE 286 dev_dbg(&spidev->spi->dev, 287 " xfer len %zd %s%s%s%dbits %u usec %uHz\n", 288 u_tmp->len, 289 u_tmp->rx_buf ? "rx " : "", 290 u_tmp->tx_buf ? "tx " : "", 291 u_tmp->cs_change ? "cs " : "", 292 u_tmp->bits_per_word ? : spidev->spi->bits_per_word, 293 u_tmp->delay_usecs, 294 u_tmp->speed_hz ? : spidev->spi->max_speed_hz); 295 #endif 296 spi_message_add_tail(k_tmp, &msg); 297 } 298 299 status = spidev_sync(spidev, &msg); 300 if (status < 0) 301 goto done; 302 303 /* copy any rx data out of bounce buffer */ 304 rx_buf = spidev->rx_buffer; 305 for (n = n_xfers, u_tmp = u_xfers; n; n--, u_tmp++) { 306 if (u_tmp->rx_buf) { 307 if (__copy_to_user((u8 __user *) 308 (uintptr_t) u_tmp->rx_buf, rx_buf, 309 u_tmp->len)) { 310 status = -EFAULT; 311 goto done; 312 } 313 rx_buf += u_tmp->len; 314 } 315 } 316 status = total; 317 318 done: 319 kfree(k_xfers); 320 return status; 321 } 322 323 static struct spi_ioc_transfer * 324 spidev_get_ioc_message(unsigned int cmd, struct spi_ioc_transfer __user *u_ioc, 325 unsigned *n_ioc) 326 { 327 struct spi_ioc_transfer *ioc; 328 u32 tmp; 329 330 /* Check type, command number and direction */ 331 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC 332 || _IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0)) 333 || _IOC_DIR(cmd) != _IOC_WRITE) 334 return ERR_PTR(-ENOTTY); 335 336 tmp = _IOC_SIZE(cmd); 337 if ((tmp % sizeof(struct spi_ioc_transfer)) != 0) 338 return ERR_PTR(-EINVAL); 339 *n_ioc = tmp / sizeof(struct spi_ioc_transfer); 340 if (*n_ioc == 0) 341 return NULL; 342 343 /* copy into scratch area */ 344 ioc = kmalloc(tmp, GFP_KERNEL); 345 if (!ioc) 346 return ERR_PTR(-ENOMEM); 347 if (__copy_from_user(ioc, u_ioc, tmp)) { 348 kfree(ioc); 349 return ERR_PTR(-EFAULT); 350 } 351 return ioc; 352 } 353 354 static long 355 spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) 356 { 357 int err = 0; 358 int retval = 0; 359 struct spidev_data *spidev; 360 struct spi_device *spi; 361 u32 tmp; 362 unsigned n_ioc; 363 struct spi_ioc_transfer *ioc; 364 365 /* Check type and command number */ 366 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC) 367 return -ENOTTY; 368 369 /* Check access direction once here; don't repeat below. 370 * IOC_DIR is from the user perspective, while access_ok is 371 * from the kernel perspective; so they look reversed. 372 */ 373 if (_IOC_DIR(cmd) & _IOC_READ) 374 err = !access_ok(VERIFY_WRITE, 375 (void __user *)arg, _IOC_SIZE(cmd)); 376 if (err == 0 && _IOC_DIR(cmd) & _IOC_WRITE) 377 err = !access_ok(VERIFY_READ, 378 (void __user *)arg, _IOC_SIZE(cmd)); 379 if (err) 380 return -EFAULT; 381 382 /* guard against device removal before, or while, 383 * we issue this ioctl. 384 */ 385 spidev = filp->private_data; 386 spin_lock_irq(&spidev->spi_lock); 387 spi = spi_dev_get(spidev->spi); 388 spin_unlock_irq(&spidev->spi_lock); 389 390 if (spi == NULL) 391 return -ESHUTDOWN; 392 393 /* use the buffer lock here for triple duty: 394 * - prevent I/O (from us) so calling spi_setup() is safe; 395 * - prevent concurrent SPI_IOC_WR_* from morphing 396 * data fields while SPI_IOC_RD_* reads them; 397 * - SPI_IOC_MESSAGE needs the buffer locked "normally". 398 */ 399 mutex_lock(&spidev->buf_lock); 400 401 switch (cmd) { 402 /* read requests */ 403 case SPI_IOC_RD_MODE: 404 retval = __put_user(spi->mode & SPI_MODE_MASK, 405 (__u8 __user *)arg); 406 break; 407 case SPI_IOC_RD_MODE32: 408 retval = __put_user(spi->mode & SPI_MODE_MASK, 409 (__u32 __user *)arg); 410 break; 411 case SPI_IOC_RD_LSB_FIRST: 412 retval = __put_user((spi->mode & SPI_LSB_FIRST) ? 1 : 0, 413 (__u8 __user *)arg); 414 break; 415 case SPI_IOC_RD_BITS_PER_WORD: 416 retval = __put_user(spi->bits_per_word, (__u8 __user *)arg); 417 break; 418 case SPI_IOC_RD_MAX_SPEED_HZ: 419 retval = __put_user(spidev->speed_hz, (__u32 __user *)arg); 420 break; 421 422 /* write requests */ 423 case SPI_IOC_WR_MODE: 424 case SPI_IOC_WR_MODE32: 425 if (cmd == SPI_IOC_WR_MODE) 426 retval = __get_user(tmp, (u8 __user *)arg); 427 else 428 retval = __get_user(tmp, (u32 __user *)arg); 429 if (retval == 0) { 430 u32 save = spi->mode; 431 432 if (tmp & ~SPI_MODE_MASK) { 433 retval = -EINVAL; 434 break; 435 } 436 437 tmp |= spi->mode & ~SPI_MODE_MASK; 438 spi->mode = (u16)tmp; 439 retval = spi_setup(spi); 440 if (retval < 0) 441 spi->mode = save; 442 else 443 dev_dbg(&spi->dev, "spi mode %x\n", tmp); 444 } 445 break; 446 case SPI_IOC_WR_LSB_FIRST: 447 retval = __get_user(tmp, (__u8 __user *)arg); 448 if (retval == 0) { 449 u32 save = spi->mode; 450 451 if (tmp) 452 spi->mode |= SPI_LSB_FIRST; 453 else 454 spi->mode &= ~SPI_LSB_FIRST; 455 retval = spi_setup(spi); 456 if (retval < 0) 457 spi->mode = save; 458 else 459 dev_dbg(&spi->dev, "%csb first\n", 460 tmp ? 'l' : 'm'); 461 } 462 break; 463 case SPI_IOC_WR_BITS_PER_WORD: 464 retval = __get_user(tmp, (__u8 __user *)arg); 465 if (retval == 0) { 466 u8 save = spi->bits_per_word; 467 468 spi->bits_per_word = tmp; 469 retval = spi_setup(spi); 470 if (retval < 0) 471 spi->bits_per_word = save; 472 else 473 dev_dbg(&spi->dev, "%d bits per word\n", tmp); 474 } 475 break; 476 case SPI_IOC_WR_MAX_SPEED_HZ: 477 retval = __get_user(tmp, (__u32 __user *)arg); 478 if (retval == 0) { 479 u32 save = spi->max_speed_hz; 480 481 spi->max_speed_hz = tmp; 482 retval = spi_setup(spi); 483 if (retval >= 0) 484 spidev->speed_hz = tmp; 485 else 486 dev_dbg(&spi->dev, "%d Hz (max)\n", tmp); 487 spi->max_speed_hz = save; 488 } 489 break; 490 491 default: 492 /* segmented and/or full-duplex I/O request */ 493 /* Check message and copy into scratch area */ 494 ioc = spidev_get_ioc_message(cmd, 495 (struct spi_ioc_transfer __user *)arg, &n_ioc); 496 if (IS_ERR(ioc)) { 497 retval = PTR_ERR(ioc); 498 break; 499 } 500 if (!ioc) 501 break; /* n_ioc is also 0 */ 502 503 /* translate to spi_message, execute */ 504 retval = spidev_message(spidev, ioc, n_ioc); 505 kfree(ioc); 506 break; 507 } 508 509 mutex_unlock(&spidev->buf_lock); 510 spi_dev_put(spi); 511 return retval; 512 } 513 514 #ifdef CONFIG_COMPAT 515 static long 516 spidev_compat_ioc_message(struct file *filp, unsigned int cmd, 517 unsigned long arg) 518 { 519 struct spi_ioc_transfer __user *u_ioc; 520 int retval = 0; 521 struct spidev_data *spidev; 522 struct spi_device *spi; 523 unsigned n_ioc, n; 524 struct spi_ioc_transfer *ioc; 525 526 u_ioc = (struct spi_ioc_transfer __user *) compat_ptr(arg); 527 if (!access_ok(VERIFY_READ, u_ioc, _IOC_SIZE(cmd))) 528 return -EFAULT; 529 530 /* guard against device removal before, or while, 531 * we issue this ioctl. 532 */ 533 spidev = filp->private_data; 534 spin_lock_irq(&spidev->spi_lock); 535 spi = spi_dev_get(spidev->spi); 536 spin_unlock_irq(&spidev->spi_lock); 537 538 if (spi == NULL) 539 return -ESHUTDOWN; 540 541 /* SPI_IOC_MESSAGE needs the buffer locked "normally" */ 542 mutex_lock(&spidev->buf_lock); 543 544 /* Check message and copy into scratch area */ 545 ioc = spidev_get_ioc_message(cmd, u_ioc, &n_ioc); 546 if (IS_ERR(ioc)) { 547 retval = PTR_ERR(ioc); 548 goto done; 549 } 550 if (!ioc) 551 goto done; /* n_ioc is also 0 */ 552 553 /* Convert buffer pointers */ 554 for (n = 0; n < n_ioc; n++) { 555 ioc[n].rx_buf = (uintptr_t) compat_ptr(ioc[n].rx_buf); 556 ioc[n].tx_buf = (uintptr_t) compat_ptr(ioc[n].tx_buf); 557 } 558 559 /* translate to spi_message, execute */ 560 retval = spidev_message(spidev, ioc, n_ioc); 561 kfree(ioc); 562 563 done: 564 mutex_unlock(&spidev->buf_lock); 565 spi_dev_put(spi); 566 return retval; 567 } 568 569 static long 570 spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) 571 { 572 if (_IOC_TYPE(cmd) == SPI_IOC_MAGIC 573 && _IOC_NR(cmd) == _IOC_NR(SPI_IOC_MESSAGE(0)) 574 && _IOC_DIR(cmd) == _IOC_WRITE) 575 return spidev_compat_ioc_message(filp, cmd, arg); 576 577 return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg)); 578 } 579 #else 580 #define spidev_compat_ioctl NULL 581 #endif /* CONFIG_COMPAT */ 582 583 static int spidev_open(struct inode *inode, struct file *filp) 584 { 585 struct spidev_data *spidev; 586 int status = -ENXIO; 587 588 mutex_lock(&device_list_lock); 589 590 list_for_each_entry(spidev, &device_list, device_entry) { 591 if (spidev->devt == inode->i_rdev) { 592 status = 0; 593 break; 594 } 595 } 596 597 if (status) { 598 pr_debug("spidev: nothing for minor %d\n", iminor(inode)); 599 goto err_find_dev; 600 } 601 602 if (!spidev->tx_buffer) { 603 spidev->tx_buffer = kmalloc(bufsiz, GFP_KERNEL); 604 if (!spidev->tx_buffer) { 605 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n"); 606 status = -ENOMEM; 607 goto err_find_dev; 608 } 609 } 610 611 if (!spidev->rx_buffer) { 612 spidev->rx_buffer = kmalloc(bufsiz, GFP_KERNEL); 613 if (!spidev->rx_buffer) { 614 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n"); 615 status = -ENOMEM; 616 goto err_alloc_rx_buf; 617 } 618 } 619 620 spidev->users++; 621 filp->private_data = spidev; 622 nonseekable_open(inode, filp); 623 624 mutex_unlock(&device_list_lock); 625 return 0; 626 627 err_alloc_rx_buf: 628 kfree(spidev->tx_buffer); 629 spidev->tx_buffer = NULL; 630 err_find_dev: 631 mutex_unlock(&device_list_lock); 632 return status; 633 } 634 635 static int spidev_release(struct inode *inode, struct file *filp) 636 { 637 struct spidev_data *spidev; 638 639 mutex_lock(&device_list_lock); 640 spidev = filp->private_data; 641 filp->private_data = NULL; 642 643 /* last close? */ 644 spidev->users--; 645 if (!spidev->users) { 646 int dofree; 647 648 kfree(spidev->tx_buffer); 649 spidev->tx_buffer = NULL; 650 651 kfree(spidev->rx_buffer); 652 spidev->rx_buffer = NULL; 653 654 if (spidev->spi) 655 spidev->speed_hz = spidev->spi->max_speed_hz; 656 657 /* ... after we unbound from the underlying device? */ 658 spin_lock_irq(&spidev->spi_lock); 659 dofree = (spidev->spi == NULL); 660 spin_unlock_irq(&spidev->spi_lock); 661 662 if (dofree) 663 kfree(spidev); 664 } 665 mutex_unlock(&device_list_lock); 666 667 return 0; 668 } 669 670 static const struct file_operations spidev_fops = { 671 .owner = THIS_MODULE, 672 /* REVISIT switch to aio primitives, so that userspace 673 * gets more complete API coverage. It'll simplify things 674 * too, except for the locking. 675 */ 676 .write = spidev_write, 677 .read = spidev_read, 678 .unlocked_ioctl = spidev_ioctl, 679 .compat_ioctl = spidev_compat_ioctl, 680 .open = spidev_open, 681 .release = spidev_release, 682 .llseek = no_llseek, 683 }; 684 685 /*-------------------------------------------------------------------------*/ 686 687 /* The main reason to have this class is to make mdev/udev create the 688 * /dev/spidevB.C character device nodes exposing our userspace API. 689 * It also simplifies memory management. 690 */ 691 692 static struct class *spidev_class; 693 694 #ifdef CONFIG_OF 695 static const struct of_device_id spidev_dt_ids[] = { 696 { .compatible = "rohm,dh2228fv" }, 697 { .compatible = "lineartechnology,ltc2488" }, 698 {}, 699 }; 700 MODULE_DEVICE_TABLE(of, spidev_dt_ids); 701 #endif 702 703 /*-------------------------------------------------------------------------*/ 704 705 static int spidev_probe(struct spi_device *spi) 706 { 707 struct spidev_data *spidev; 708 int status; 709 unsigned long minor; 710 711 /* 712 * spidev should never be referenced in DT without a specific 713 * compatible string, it is a Linux implementation thing 714 * rather than a description of the hardware. 715 */ 716 if (spi->dev.of_node && !of_match_device(spidev_dt_ids, &spi->dev)) { 717 dev_err(&spi->dev, "buggy DT: spidev listed directly in DT\n"); 718 WARN_ON(spi->dev.of_node && 719 !of_match_device(spidev_dt_ids, &spi->dev)); 720 } 721 722 /* Allocate driver data */ 723 spidev = kzalloc(sizeof(*spidev), GFP_KERNEL); 724 if (!spidev) 725 return -ENOMEM; 726 727 /* Initialize the driver data */ 728 spidev->spi = spi; 729 spin_lock_init(&spidev->spi_lock); 730 mutex_init(&spidev->buf_lock); 731 732 INIT_LIST_HEAD(&spidev->device_entry); 733 734 /* If we can allocate a minor number, hook up this device. 735 * Reusing minors is fine so long as udev or mdev is working. 736 */ 737 mutex_lock(&device_list_lock); 738 minor = find_first_zero_bit(minors, N_SPI_MINORS); 739 if (minor < N_SPI_MINORS) { 740 struct device *dev; 741 742 spidev->devt = MKDEV(SPIDEV_MAJOR, minor); 743 dev = device_create(spidev_class, &spi->dev, spidev->devt, 744 spidev, "spidev%d.%d", 745 spi->master->bus_num, spi->chip_select); 746 status = PTR_ERR_OR_ZERO(dev); 747 } else { 748 dev_dbg(&spi->dev, "no minor number available!\n"); 749 status = -ENODEV; 750 } 751 if (status == 0) { 752 set_bit(minor, minors); 753 list_add(&spidev->device_entry, &device_list); 754 } 755 mutex_unlock(&device_list_lock); 756 757 spidev->speed_hz = spi->max_speed_hz; 758 759 if (status == 0) 760 spi_set_drvdata(spi, spidev); 761 else 762 kfree(spidev); 763 764 return status; 765 } 766 767 static int spidev_remove(struct spi_device *spi) 768 { 769 struct spidev_data *spidev = spi_get_drvdata(spi); 770 771 /* make sure ops on existing fds can abort cleanly */ 772 spin_lock_irq(&spidev->spi_lock); 773 spidev->spi = NULL; 774 spin_unlock_irq(&spidev->spi_lock); 775 776 /* prevent new opens */ 777 mutex_lock(&device_list_lock); 778 list_del(&spidev->device_entry); 779 device_destroy(spidev_class, spidev->devt); 780 clear_bit(MINOR(spidev->devt), minors); 781 if (spidev->users == 0) 782 kfree(spidev); 783 mutex_unlock(&device_list_lock); 784 785 return 0; 786 } 787 788 static struct spi_driver spidev_spi_driver = { 789 .driver = { 790 .name = "spidev", 791 .owner = THIS_MODULE, 792 .of_match_table = of_match_ptr(spidev_dt_ids), 793 }, 794 .probe = spidev_probe, 795 .remove = spidev_remove, 796 797 /* NOTE: suspend/resume methods are not necessary here. 798 * We don't do anything except pass the requests to/from 799 * the underlying controller. The refrigerator handles 800 * most issues; the controller driver handles the rest. 801 */ 802 }; 803 804 /*-------------------------------------------------------------------------*/ 805 806 static int __init spidev_init(void) 807 { 808 int status; 809 810 /* Claim our 256 reserved device numbers. Then register a class 811 * that will key udev/mdev to add/remove /dev nodes. Last, register 812 * the driver which manages those device numbers. 813 */ 814 BUILD_BUG_ON(N_SPI_MINORS > 256); 815 status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops); 816 if (status < 0) 817 return status; 818 819 spidev_class = class_create(THIS_MODULE, "spidev"); 820 if (IS_ERR(spidev_class)) { 821 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name); 822 return PTR_ERR(spidev_class); 823 } 824 825 status = spi_register_driver(&spidev_spi_driver); 826 if (status < 0) { 827 class_destroy(spidev_class); 828 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name); 829 } 830 return status; 831 } 832 module_init(spidev_init); 833 834 static void __exit spidev_exit(void) 835 { 836 spi_unregister_driver(&spidev_spi_driver); 837 class_destroy(spidev_class); 838 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name); 839 } 840 module_exit(spidev_exit); 841 842 MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>"); 843 MODULE_DESCRIPTION("User mode SPI device interface"); 844 MODULE_LICENSE("GPL"); 845 MODULE_ALIAS("spi:spidev"); 846