1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Simple synchronous userspace interface to SPI devices 4 * 5 * Copyright (C) 2006 SWAPP 6 * Andrea Paterniani <a.paterniani@swapp-eng.it> 7 * Copyright (C) 2007 David Brownell (simplification, cleanup) 8 */ 9 10 #include <linux/init.h> 11 #include <linux/ioctl.h> 12 #include <linux/fs.h> 13 #include <linux/device.h> 14 #include <linux/err.h> 15 #include <linux/list.h> 16 #include <linux/errno.h> 17 #include <linux/mod_devicetable.h> 18 #include <linux/module.h> 19 #include <linux/mutex.h> 20 #include <linux/property.h> 21 #include <linux/slab.h> 22 #include <linux/compat.h> 23 24 #include <linux/spi/spi.h> 25 #include <linux/spi/spidev.h> 26 27 #include <linux/uaccess.h> 28 29 30 /* 31 * This supports access to SPI devices using normal userspace I/O calls. 32 * Note that while traditional UNIX/POSIX I/O semantics are half duplex, 33 * and often mask message boundaries, full SPI support requires full duplex 34 * transfers. There are several kinds of internal message boundaries to 35 * handle chipselect management and other protocol options. 36 * 37 * SPI has a character major number assigned. We allocate minor numbers 38 * dynamically using a bitmask. You must use hotplug tools, such as udev 39 * (or mdev with busybox) to create and destroy the /dev/spidevB.C device 40 * nodes, since there is no fixed association of minor numbers with any 41 * particular SPI bus or device. 42 */ 43 #define SPIDEV_MAJOR 153 /* assigned */ 44 #define N_SPI_MINORS 32 /* ... up to 256 */ 45 46 static DECLARE_BITMAP(minors, N_SPI_MINORS); 47 48 static_assert(N_SPI_MINORS > 0 && N_SPI_MINORS <= 256); 49 50 /* Bit masks for spi_device.mode management. Note that incorrect 51 * settings for some settings can cause *lots* of trouble for other 52 * devices on a shared bus: 53 * 54 * - CS_HIGH ... this device will be active when it shouldn't be 55 * - 3WIRE ... when active, it won't behave as it should 56 * - NO_CS ... there will be no explicit message boundaries; this 57 * is completely incompatible with the shared bus model 58 * - READY ... transfers may proceed when they shouldn't. 59 * 60 * REVISIT should changing those flags be privileged? 61 */ 62 #define SPI_MODE_MASK (SPI_MODE_X_MASK | SPI_CS_HIGH \ 63 | SPI_LSB_FIRST | SPI_3WIRE | SPI_LOOP \ 64 | SPI_NO_CS | SPI_READY | SPI_TX_DUAL \ 65 | SPI_TX_QUAD | SPI_TX_OCTAL | SPI_RX_DUAL \ 66 | SPI_RX_QUAD | SPI_RX_OCTAL \ 67 | SPI_RX_CPHA_FLIP) 68 69 struct spidev_data { 70 dev_t devt; 71 struct mutex spi_lock; 72 struct spi_device *spi; 73 struct list_head device_entry; 74 75 /* TX/RX buffers are NULL unless this device is open (users > 0) */ 76 struct mutex buf_lock; 77 unsigned users; 78 u8 *tx_buffer; 79 u8 *rx_buffer; 80 u32 speed_hz; 81 }; 82 83 static LIST_HEAD(device_list); 84 static DEFINE_MUTEX(device_list_lock); 85 86 static unsigned bufsiz = 4096; 87 module_param(bufsiz, uint, S_IRUGO); 88 MODULE_PARM_DESC(bufsiz, "data bytes in biggest supported SPI message"); 89 90 /*-------------------------------------------------------------------------*/ 91 92 static ssize_t 93 spidev_sync(struct spidev_data *spidev, struct spi_message *message) 94 { 95 int status; 96 struct spi_device *spi; 97 98 mutex_lock(&spidev->spi_lock); 99 spi = spidev->spi; 100 101 if (spi == NULL) 102 status = -ESHUTDOWN; 103 else 104 status = spi_sync(spi, message); 105 106 if (status == 0) 107 status = message->actual_length; 108 109 mutex_unlock(&spidev->spi_lock); 110 return status; 111 } 112 113 static inline ssize_t 114 spidev_sync_write(struct spidev_data *spidev, size_t len) 115 { 116 struct spi_transfer t = { 117 .tx_buf = spidev->tx_buffer, 118 .len = len, 119 .speed_hz = spidev->speed_hz, 120 }; 121 struct spi_message m; 122 123 spi_message_init(&m); 124 spi_message_add_tail(&t, &m); 125 return spidev_sync(spidev, &m); 126 } 127 128 static inline ssize_t 129 spidev_sync_read(struct spidev_data *spidev, size_t len) 130 { 131 struct spi_transfer t = { 132 .rx_buf = spidev->rx_buffer, 133 .len = len, 134 .speed_hz = spidev->speed_hz, 135 }; 136 struct spi_message m; 137 138 spi_message_init(&m); 139 spi_message_add_tail(&t, &m); 140 return spidev_sync(spidev, &m); 141 } 142 143 /*-------------------------------------------------------------------------*/ 144 145 /* Read-only message with current device setup */ 146 static ssize_t 147 spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos) 148 { 149 struct spidev_data *spidev; 150 ssize_t status; 151 152 /* chipselect only toggles at start or end of operation */ 153 if (count > bufsiz) 154 return -EMSGSIZE; 155 156 spidev = filp->private_data; 157 158 mutex_lock(&spidev->buf_lock); 159 status = spidev_sync_read(spidev, count); 160 if (status > 0) { 161 unsigned long missing; 162 163 missing = copy_to_user(buf, spidev->rx_buffer, status); 164 if (missing == status) 165 status = -EFAULT; 166 else 167 status = status - missing; 168 } 169 mutex_unlock(&spidev->buf_lock); 170 171 return status; 172 } 173 174 /* Write-only message with current device setup */ 175 static ssize_t 176 spidev_write(struct file *filp, const char __user *buf, 177 size_t count, loff_t *f_pos) 178 { 179 struct spidev_data *spidev; 180 ssize_t status; 181 unsigned long missing; 182 183 /* chipselect only toggles at start or end of operation */ 184 if (count > bufsiz) 185 return -EMSGSIZE; 186 187 spidev = filp->private_data; 188 189 mutex_lock(&spidev->buf_lock); 190 missing = copy_from_user(spidev->tx_buffer, buf, count); 191 if (missing == 0) 192 status = spidev_sync_write(spidev, count); 193 else 194 status = -EFAULT; 195 mutex_unlock(&spidev->buf_lock); 196 197 return status; 198 } 199 200 static int spidev_message(struct spidev_data *spidev, 201 struct spi_ioc_transfer *u_xfers, unsigned n_xfers) 202 { 203 struct spi_message msg; 204 struct spi_transfer *k_xfers; 205 struct spi_transfer *k_tmp; 206 struct spi_ioc_transfer *u_tmp; 207 unsigned n, total, tx_total, rx_total; 208 u8 *tx_buf, *rx_buf; 209 int status = -EFAULT; 210 211 spi_message_init(&msg); 212 k_xfers = kcalloc(n_xfers, sizeof(*k_tmp), GFP_KERNEL); 213 if (k_xfers == NULL) 214 return -ENOMEM; 215 216 /* Construct spi_message, copying any tx data to bounce buffer. 217 * We walk the array of user-provided transfers, using each one 218 * to initialize a kernel version of the same transfer. 219 */ 220 tx_buf = spidev->tx_buffer; 221 rx_buf = spidev->rx_buffer; 222 total = 0; 223 tx_total = 0; 224 rx_total = 0; 225 for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers; 226 n; 227 n--, k_tmp++, u_tmp++) { 228 /* Ensure that also following allocations from rx_buf/tx_buf will meet 229 * DMA alignment requirements. 230 */ 231 unsigned int len_aligned = ALIGN(u_tmp->len, ARCH_KMALLOC_MINALIGN); 232 233 k_tmp->len = u_tmp->len; 234 235 total += k_tmp->len; 236 /* Since the function returns the total length of transfers 237 * on success, restrict the total to positive int values to 238 * avoid the return value looking like an error. Also check 239 * each transfer length to avoid arithmetic overflow. 240 */ 241 if (total > INT_MAX || k_tmp->len > INT_MAX) { 242 status = -EMSGSIZE; 243 goto done; 244 } 245 246 if (u_tmp->rx_buf) { 247 /* this transfer needs space in RX bounce buffer */ 248 rx_total += len_aligned; 249 if (rx_total > bufsiz) { 250 status = -EMSGSIZE; 251 goto done; 252 } 253 k_tmp->rx_buf = rx_buf; 254 rx_buf += len_aligned; 255 } 256 if (u_tmp->tx_buf) { 257 /* this transfer needs space in TX bounce buffer */ 258 tx_total += len_aligned; 259 if (tx_total > bufsiz) { 260 status = -EMSGSIZE; 261 goto done; 262 } 263 k_tmp->tx_buf = tx_buf; 264 if (copy_from_user(tx_buf, (const u8 __user *) 265 (uintptr_t) u_tmp->tx_buf, 266 u_tmp->len)) 267 goto done; 268 tx_buf += len_aligned; 269 } 270 271 k_tmp->cs_change = !!u_tmp->cs_change; 272 k_tmp->tx_nbits = u_tmp->tx_nbits; 273 k_tmp->rx_nbits = u_tmp->rx_nbits; 274 k_tmp->bits_per_word = u_tmp->bits_per_word; 275 k_tmp->delay.value = u_tmp->delay_usecs; 276 k_tmp->delay.unit = SPI_DELAY_UNIT_USECS; 277 k_tmp->speed_hz = u_tmp->speed_hz; 278 k_tmp->word_delay.value = u_tmp->word_delay_usecs; 279 k_tmp->word_delay.unit = SPI_DELAY_UNIT_USECS; 280 if (!k_tmp->speed_hz) 281 k_tmp->speed_hz = spidev->speed_hz; 282 #ifdef VERBOSE 283 dev_dbg(&spidev->spi->dev, 284 " xfer len %u %s%s%s%dbits %u usec %u usec %uHz\n", 285 k_tmp->len, 286 k_tmp->rx_buf ? "rx " : "", 287 k_tmp->tx_buf ? "tx " : "", 288 k_tmp->cs_change ? "cs " : "", 289 k_tmp->bits_per_word ? : spidev->spi->bits_per_word, 290 k_tmp->delay.value, 291 k_tmp->word_delay.value, 292 k_tmp->speed_hz ? : spidev->spi->max_speed_hz); 293 #endif 294 spi_message_add_tail(k_tmp, &msg); 295 } 296 297 status = spidev_sync(spidev, &msg); 298 if (status < 0) 299 goto done; 300 301 /* copy any rx data out of bounce buffer */ 302 for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers; 303 n; 304 n--, k_tmp++, u_tmp++) { 305 if (u_tmp->rx_buf) { 306 if (copy_to_user((u8 __user *) 307 (uintptr_t) u_tmp->rx_buf, k_tmp->rx_buf, 308 u_tmp->len)) { 309 status = -EFAULT; 310 goto done; 311 } 312 } 313 } 314 status = total; 315 316 done: 317 kfree(k_xfers); 318 return status; 319 } 320 321 static struct spi_ioc_transfer * 322 spidev_get_ioc_message(unsigned int cmd, struct spi_ioc_transfer __user *u_ioc, 323 unsigned *n_ioc) 324 { 325 u32 tmp; 326 327 /* Check type, command number and direction */ 328 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC 329 || _IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0)) 330 || _IOC_DIR(cmd) != _IOC_WRITE) 331 return ERR_PTR(-ENOTTY); 332 333 tmp = _IOC_SIZE(cmd); 334 if ((tmp % sizeof(struct spi_ioc_transfer)) != 0) 335 return ERR_PTR(-EINVAL); 336 *n_ioc = tmp / sizeof(struct spi_ioc_transfer); 337 if (*n_ioc == 0) 338 return NULL; 339 340 /* copy into scratch area */ 341 return memdup_user(u_ioc, tmp); 342 } 343 344 static long 345 spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) 346 { 347 int retval = 0; 348 struct spidev_data *spidev; 349 struct spi_device *spi; 350 u32 tmp; 351 unsigned n_ioc; 352 struct spi_ioc_transfer *ioc; 353 354 /* Check type and command number */ 355 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC) 356 return -ENOTTY; 357 358 /* guard against device removal before, or while, 359 * we issue this ioctl. 360 */ 361 spidev = filp->private_data; 362 mutex_lock(&spidev->spi_lock); 363 spi = spi_dev_get(spidev->spi); 364 if (spi == NULL) { 365 mutex_unlock(&spidev->spi_lock); 366 return -ESHUTDOWN; 367 } 368 369 /* use the buffer lock here for triple duty: 370 * - prevent I/O (from us) so calling spi_setup() is safe; 371 * - prevent concurrent SPI_IOC_WR_* from morphing 372 * data fields while SPI_IOC_RD_* reads them; 373 * - SPI_IOC_MESSAGE needs the buffer locked "normally". 374 */ 375 mutex_lock(&spidev->buf_lock); 376 377 switch (cmd) { 378 /* read requests */ 379 case SPI_IOC_RD_MODE: 380 case SPI_IOC_RD_MODE32: 381 tmp = spi->mode; 382 383 { 384 struct spi_controller *ctlr = spi->controller; 385 386 if (ctlr->use_gpio_descriptors && ctlr->cs_gpiods && 387 ctlr->cs_gpiods[spi->chip_select]) 388 tmp &= ~SPI_CS_HIGH; 389 } 390 391 if (cmd == SPI_IOC_RD_MODE) 392 retval = put_user(tmp & SPI_MODE_MASK, 393 (__u8 __user *)arg); 394 else 395 retval = put_user(tmp & SPI_MODE_MASK, 396 (__u32 __user *)arg); 397 break; 398 case SPI_IOC_RD_LSB_FIRST: 399 retval = put_user((spi->mode & SPI_LSB_FIRST) ? 1 : 0, 400 (__u8 __user *)arg); 401 break; 402 case SPI_IOC_RD_BITS_PER_WORD: 403 retval = put_user(spi->bits_per_word, (__u8 __user *)arg); 404 break; 405 case SPI_IOC_RD_MAX_SPEED_HZ: 406 retval = put_user(spidev->speed_hz, (__u32 __user *)arg); 407 break; 408 409 /* write requests */ 410 case SPI_IOC_WR_MODE: 411 case SPI_IOC_WR_MODE32: 412 if (cmd == SPI_IOC_WR_MODE) 413 retval = get_user(tmp, (u8 __user *)arg); 414 else 415 retval = get_user(tmp, (u32 __user *)arg); 416 if (retval == 0) { 417 struct spi_controller *ctlr = spi->controller; 418 u32 save = spi->mode; 419 420 if (tmp & ~SPI_MODE_MASK) { 421 retval = -EINVAL; 422 break; 423 } 424 425 if (ctlr->use_gpio_descriptors && ctlr->cs_gpiods && 426 ctlr->cs_gpiods[spi->chip_select]) 427 tmp |= SPI_CS_HIGH; 428 429 tmp |= spi->mode & ~SPI_MODE_MASK; 430 spi->mode = tmp & SPI_MODE_USER_MASK; 431 retval = spi_setup(spi); 432 if (retval < 0) 433 spi->mode = save; 434 else 435 dev_dbg(&spi->dev, "spi mode %x\n", tmp); 436 } 437 break; 438 case SPI_IOC_WR_LSB_FIRST: 439 retval = get_user(tmp, (__u8 __user *)arg); 440 if (retval == 0) { 441 u32 save = spi->mode; 442 443 if (tmp) 444 spi->mode |= SPI_LSB_FIRST; 445 else 446 spi->mode &= ~SPI_LSB_FIRST; 447 retval = spi_setup(spi); 448 if (retval < 0) 449 spi->mode = save; 450 else 451 dev_dbg(&spi->dev, "%csb first\n", 452 tmp ? 'l' : 'm'); 453 } 454 break; 455 case SPI_IOC_WR_BITS_PER_WORD: 456 retval = get_user(tmp, (__u8 __user *)arg); 457 if (retval == 0) { 458 u8 save = spi->bits_per_word; 459 460 spi->bits_per_word = tmp; 461 retval = spi_setup(spi); 462 if (retval < 0) 463 spi->bits_per_word = save; 464 else 465 dev_dbg(&spi->dev, "%d bits per word\n", tmp); 466 } 467 break; 468 case SPI_IOC_WR_MAX_SPEED_HZ: { 469 u32 save; 470 471 retval = get_user(tmp, (__u32 __user *)arg); 472 if (retval) 473 break; 474 if (tmp == 0) { 475 retval = -EINVAL; 476 break; 477 } 478 479 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 dev_dbg(&spi->dev, "%d Hz (max)\n", spidev->speed_hz); 486 } 487 488 spi->max_speed_hz = save; 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 mutex_unlock(&spidev->spi_lock); 512 return retval; 513 } 514 515 #ifdef CONFIG_COMPAT 516 static long 517 spidev_compat_ioc_message(struct file *filp, unsigned int cmd, 518 unsigned long arg) 519 { 520 struct spi_ioc_transfer __user *u_ioc; 521 int retval = 0; 522 struct spidev_data *spidev; 523 struct spi_device *spi; 524 unsigned n_ioc, n; 525 struct spi_ioc_transfer *ioc; 526 527 u_ioc = (struct spi_ioc_transfer __user *) compat_ptr(arg); 528 529 /* guard against device removal before, or while, 530 * we issue this ioctl. 531 */ 532 spidev = filp->private_data; 533 mutex_lock(&spidev->spi_lock); 534 spi = spi_dev_get(spidev->spi); 535 if (spi == NULL) { 536 mutex_unlock(&spidev->spi_lock); 537 return -ESHUTDOWN; 538 } 539 540 /* SPI_IOC_MESSAGE needs the buffer locked "normally" */ 541 mutex_lock(&spidev->buf_lock); 542 543 /* Check message and copy into scratch area */ 544 ioc = spidev_get_ioc_message(cmd, u_ioc, &n_ioc); 545 if (IS_ERR(ioc)) { 546 retval = PTR_ERR(ioc); 547 goto done; 548 } 549 if (!ioc) 550 goto done; /* n_ioc is also 0 */ 551 552 /* Convert buffer pointers */ 553 for (n = 0; n < n_ioc; n++) { 554 ioc[n].rx_buf = (uintptr_t) compat_ptr(ioc[n].rx_buf); 555 ioc[n].tx_buf = (uintptr_t) compat_ptr(ioc[n].tx_buf); 556 } 557 558 /* translate to spi_message, execute */ 559 retval = spidev_message(spidev, ioc, n_ioc); 560 kfree(ioc); 561 562 done: 563 mutex_unlock(&spidev->buf_lock); 564 spi_dev_put(spi); 565 mutex_unlock(&spidev->spi_lock); 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 = NULL, *iter; 586 int status = -ENXIO; 587 588 mutex_lock(&device_list_lock); 589 590 list_for_each_entry(iter, &device_list, device_entry) { 591 if (iter->devt == inode->i_rdev) { 592 status = 0; 593 spidev = iter; 594 break; 595 } 596 } 597 598 if (!spidev) { 599 pr_debug("spidev: nothing for minor %d\n", iminor(inode)); 600 goto err_find_dev; 601 } 602 603 if (!spidev->tx_buffer) { 604 spidev->tx_buffer = kmalloc(bufsiz, GFP_KERNEL); 605 if (!spidev->tx_buffer) { 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 status = -ENOMEM; 615 goto err_alloc_rx_buf; 616 } 617 } 618 619 spidev->users++; 620 filp->private_data = spidev; 621 stream_open(inode, filp); 622 623 mutex_unlock(&device_list_lock); 624 return 0; 625 626 err_alloc_rx_buf: 627 kfree(spidev->tx_buffer); 628 spidev->tx_buffer = NULL; 629 err_find_dev: 630 mutex_unlock(&device_list_lock); 631 return status; 632 } 633 634 static int spidev_release(struct inode *inode, struct file *filp) 635 { 636 struct spidev_data *spidev; 637 int dofree; 638 639 mutex_lock(&device_list_lock); 640 spidev = filp->private_data; 641 filp->private_data = NULL; 642 643 mutex_lock(&spidev->spi_lock); 644 /* ... after we unbound from the underlying device? */ 645 dofree = (spidev->spi == NULL); 646 mutex_unlock(&spidev->spi_lock); 647 648 /* last close? */ 649 spidev->users--; 650 if (!spidev->users) { 651 652 kfree(spidev->tx_buffer); 653 spidev->tx_buffer = NULL; 654 655 kfree(spidev->rx_buffer); 656 spidev->rx_buffer = NULL; 657 658 if (dofree) 659 kfree(spidev); 660 else 661 spidev->speed_hz = spidev->spi->max_speed_hz; 662 } 663 #ifdef CONFIG_SPI_SLAVE 664 if (!dofree) 665 spi_slave_abort(spidev->spi); 666 #endif 667 mutex_unlock(&device_list_lock); 668 669 return 0; 670 } 671 672 static const struct file_operations spidev_fops = { 673 .owner = THIS_MODULE, 674 /* REVISIT switch to aio primitives, so that userspace 675 * gets more complete API coverage. It'll simplify things 676 * too, except for the locking. 677 */ 678 .write = spidev_write, 679 .read = spidev_read, 680 .unlocked_ioctl = spidev_ioctl, 681 .compat_ioctl = spidev_compat_ioctl, 682 .open = spidev_open, 683 .release = spidev_release, 684 .llseek = no_llseek, 685 }; 686 687 /*-------------------------------------------------------------------------*/ 688 689 /* The main reason to have this class is to make mdev/udev create the 690 * /dev/spidevB.C character device nodes exposing our userspace API. 691 * It also simplifies memory management. 692 */ 693 694 static struct class *spidev_class; 695 696 static const struct spi_device_id spidev_spi_ids[] = { 697 { .name = "dh2228fv" }, 698 { .name = "ltc2488" }, 699 { .name = "sx1301" }, 700 { .name = "bk4" }, 701 { .name = "dhcom-board" }, 702 { .name = "m53cpld" }, 703 { .name = "spi-petra" }, 704 { .name = "spi-authenta" }, 705 {}, 706 }; 707 MODULE_DEVICE_TABLE(spi, spidev_spi_ids); 708 709 /* 710 * spidev should never be referenced in DT without a specific compatible string, 711 * it is a Linux implementation thing rather than a description of the hardware. 712 */ 713 static int spidev_of_check(struct device *dev) 714 { 715 if (device_property_match_string(dev, "compatible", "spidev") < 0) 716 return 0; 717 718 dev_err(dev, "spidev listed directly in DT is not supported\n"); 719 return -EINVAL; 720 } 721 722 static const struct of_device_id spidev_dt_ids[] = { 723 { .compatible = "rohm,dh2228fv", .data = &spidev_of_check }, 724 { .compatible = "lineartechnology,ltc2488", .data = &spidev_of_check }, 725 { .compatible = "semtech,sx1301", .data = &spidev_of_check }, 726 { .compatible = "lwn,bk4", .data = &spidev_of_check }, 727 { .compatible = "dh,dhcom-board", .data = &spidev_of_check }, 728 { .compatible = "menlo,m53cpld", .data = &spidev_of_check }, 729 { .compatible = "cisco,spi-petra", .data = &spidev_of_check }, 730 { .compatible = "micron,spi-authenta", .data = &spidev_of_check }, 731 {}, 732 }; 733 MODULE_DEVICE_TABLE(of, spidev_dt_ids); 734 735 /* Dummy SPI devices not to be used in production systems */ 736 static int spidev_acpi_check(struct device *dev) 737 { 738 dev_warn(dev, "do not use this driver in production systems!\n"); 739 return 0; 740 } 741 742 static const struct acpi_device_id spidev_acpi_ids[] = { 743 /* 744 * The ACPI SPT000* devices are only meant for development and 745 * testing. Systems used in production should have a proper ACPI 746 * description of the connected peripheral and they should also use 747 * a proper driver instead of poking directly to the SPI bus. 748 */ 749 { "SPT0001", (kernel_ulong_t)&spidev_acpi_check }, 750 { "SPT0002", (kernel_ulong_t)&spidev_acpi_check }, 751 { "SPT0003", (kernel_ulong_t)&spidev_acpi_check }, 752 {}, 753 }; 754 MODULE_DEVICE_TABLE(acpi, spidev_acpi_ids); 755 756 /*-------------------------------------------------------------------------*/ 757 758 static int spidev_probe(struct spi_device *spi) 759 { 760 int (*match)(struct device *dev); 761 struct spidev_data *spidev; 762 int status; 763 unsigned long minor; 764 765 match = device_get_match_data(&spi->dev); 766 if (match) { 767 status = match(&spi->dev); 768 if (status) 769 return status; 770 } 771 772 /* Allocate driver data */ 773 spidev = kzalloc(sizeof(*spidev), GFP_KERNEL); 774 if (!spidev) 775 return -ENOMEM; 776 777 /* Initialize the driver data */ 778 spidev->spi = spi; 779 mutex_init(&spidev->spi_lock); 780 mutex_init(&spidev->buf_lock); 781 782 INIT_LIST_HEAD(&spidev->device_entry); 783 784 /* If we can allocate a minor number, hook up this device. 785 * Reusing minors is fine so long as udev or mdev is working. 786 */ 787 mutex_lock(&device_list_lock); 788 minor = find_first_zero_bit(minors, N_SPI_MINORS); 789 if (minor < N_SPI_MINORS) { 790 struct device *dev; 791 792 spidev->devt = MKDEV(SPIDEV_MAJOR, minor); 793 dev = device_create(spidev_class, &spi->dev, spidev->devt, 794 spidev, "spidev%d.%d", 795 spi->master->bus_num, spi->chip_select); 796 status = PTR_ERR_OR_ZERO(dev); 797 } else { 798 dev_dbg(&spi->dev, "no minor number available!\n"); 799 status = -ENODEV; 800 } 801 if (status == 0) { 802 set_bit(minor, minors); 803 list_add(&spidev->device_entry, &device_list); 804 } 805 mutex_unlock(&device_list_lock); 806 807 spidev->speed_hz = spi->max_speed_hz; 808 809 if (status == 0) 810 spi_set_drvdata(spi, spidev); 811 else 812 kfree(spidev); 813 814 return status; 815 } 816 817 static void spidev_remove(struct spi_device *spi) 818 { 819 struct spidev_data *spidev = spi_get_drvdata(spi); 820 821 /* prevent new opens */ 822 mutex_lock(&device_list_lock); 823 /* make sure ops on existing fds can abort cleanly */ 824 mutex_lock(&spidev->spi_lock); 825 spidev->spi = NULL; 826 mutex_unlock(&spidev->spi_lock); 827 828 list_del(&spidev->device_entry); 829 device_destroy(spidev_class, spidev->devt); 830 clear_bit(MINOR(spidev->devt), minors); 831 if (spidev->users == 0) 832 kfree(spidev); 833 mutex_unlock(&device_list_lock); 834 } 835 836 static struct spi_driver spidev_spi_driver = { 837 .driver = { 838 .name = "spidev", 839 .of_match_table = spidev_dt_ids, 840 .acpi_match_table = spidev_acpi_ids, 841 }, 842 .probe = spidev_probe, 843 .remove = spidev_remove, 844 .id_table = spidev_spi_ids, 845 846 /* NOTE: suspend/resume methods are not necessary here. 847 * We don't do anything except pass the requests to/from 848 * the underlying controller. The refrigerator handles 849 * most issues; the controller driver handles the rest. 850 */ 851 }; 852 853 /*-------------------------------------------------------------------------*/ 854 855 static int __init spidev_init(void) 856 { 857 int status; 858 859 /* Claim our 256 reserved device numbers. Then register a class 860 * that will key udev/mdev to add/remove /dev nodes. Last, register 861 * the driver which manages those device numbers. 862 */ 863 status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops); 864 if (status < 0) 865 return status; 866 867 spidev_class = class_create(THIS_MODULE, "spidev"); 868 if (IS_ERR(spidev_class)) { 869 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name); 870 return PTR_ERR(spidev_class); 871 } 872 873 status = spi_register_driver(&spidev_spi_driver); 874 if (status < 0) { 875 class_destroy(spidev_class); 876 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name); 877 } 878 return status; 879 } 880 module_init(spidev_init); 881 882 static void __exit spidev_exit(void) 883 { 884 spi_unregister_driver(&spidev_spi_driver); 885 class_destroy(spidev_class); 886 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name); 887 } 888 module_exit(spidev_exit); 889 890 MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>"); 891 MODULE_DESCRIPTION("User mode SPI device interface"); 892 MODULE_LICENSE("GPL"); 893 MODULE_ALIAS("spi:spidev"); 894