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/module.h> 12 #include <linux/ioctl.h> 13 #include <linux/fs.h> 14 #include <linux/device.h> 15 #include <linux/err.h> 16 #include <linux/list.h> 17 #include <linux/errno.h> 18 #include <linux/mutex.h> 19 #include <linux/slab.h> 20 #include <linux/compat.h> 21 #include <linux/of.h> 22 #include <linux/of_device.h> 23 #include <linux/acpi.h> 24 25 #include <linux/spi/spi.h> 26 #include <linux/spi/spidev.h> 27 28 #include <linux/uaccess.h> 29 30 31 /* 32 * This supports access to SPI devices using normal userspace I/O calls. 33 * Note that while traditional UNIX/POSIX I/O semantics are half duplex, 34 * and often mask message boundaries, full SPI support requires full duplex 35 * transfers. There are several kinds of internal message boundaries to 36 * handle chipselect management and other protocol options. 37 * 38 * SPI has a character major number assigned. We allocate minor numbers 39 * dynamically using a bitmask. You must use hotplug tools, such as udev 40 * (or mdev with busybox) to create and destroy the /dev/spidevB.C device 41 * nodes, since there is no fixed association of minor numbers with any 42 * particular SPI bus or device. 43 */ 44 #define SPIDEV_MAJOR 153 /* assigned */ 45 #define N_SPI_MINORS 32 /* ... up to 256 */ 46 47 static DECLARE_BITMAP(minors, N_SPI_MINORS); 48 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 68 struct spidev_data { 69 dev_t devt; 70 spinlock_t spi_lock; 71 struct spi_device *spi; 72 struct list_head device_entry; 73 74 /* TX/RX buffers are NULL unless this device is open (users > 0) */ 75 struct mutex buf_lock; 76 unsigned users; 77 u8 *tx_buffer; 78 u8 *rx_buffer; 79 u32 speed_hz; 80 }; 81 82 static LIST_HEAD(device_list); 83 static DEFINE_MUTEX(device_list_lock); 84 85 static unsigned bufsiz = 4096; 86 module_param(bufsiz, uint, S_IRUGO); 87 MODULE_PARM_DESC(bufsiz, "data bytes in biggest supported SPI message"); 88 89 /*-------------------------------------------------------------------------*/ 90 91 static ssize_t 92 spidev_sync(struct spidev_data *spidev, struct spi_message *message) 93 { 94 int status; 95 struct spi_device *spi; 96 97 spin_lock_irq(&spidev->spi_lock); 98 spi = spidev->spi; 99 spin_unlock_irq(&spidev->spi_lock); 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 return status; 110 } 111 112 static inline ssize_t 113 spidev_sync_write(struct spidev_data *spidev, size_t len) 114 { 115 struct spi_transfer t = { 116 .tx_buf = spidev->tx_buffer, 117 .len = len, 118 .speed_hz = spidev->speed_hz, 119 }; 120 struct spi_message m; 121 122 spi_message_init(&m); 123 spi_message_add_tail(&t, &m); 124 return spidev_sync(spidev, &m); 125 } 126 127 static inline ssize_t 128 spidev_sync_read(struct spidev_data *spidev, size_t len) 129 { 130 struct spi_transfer t = { 131 .rx_buf = spidev->rx_buffer, 132 .len = len, 133 .speed_hz = spidev->speed_hz, 134 }; 135 struct spi_message m; 136 137 spi_message_init(&m); 138 spi_message_add_tail(&t, &m); 139 return spidev_sync(spidev, &m); 140 } 141 142 /*-------------------------------------------------------------------------*/ 143 144 /* Read-only message with current device setup */ 145 static ssize_t 146 spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos) 147 { 148 struct spidev_data *spidev; 149 ssize_t status; 150 151 /* chipselect only toggles at start or end of operation */ 152 if (count > bufsiz) 153 return -EMSGSIZE; 154 155 spidev = filp->private_data; 156 157 mutex_lock(&spidev->buf_lock); 158 status = spidev_sync_read(spidev, count); 159 if (status > 0) { 160 unsigned long missing; 161 162 missing = copy_to_user(buf, spidev->rx_buffer, status); 163 if (missing == status) 164 status = -EFAULT; 165 else 166 status = status - missing; 167 } 168 mutex_unlock(&spidev->buf_lock); 169 170 return status; 171 } 172 173 /* Write-only message with current device setup */ 174 static ssize_t 175 spidev_write(struct file *filp, const char __user *buf, 176 size_t count, loff_t *f_pos) 177 { 178 struct spidev_data *spidev; 179 ssize_t status; 180 unsigned long missing; 181 182 /* chipselect only toggles at start or end of operation */ 183 if (count > bufsiz) 184 return -EMSGSIZE; 185 186 spidev = filp->private_data; 187 188 mutex_lock(&spidev->buf_lock); 189 missing = copy_from_user(spidev->tx_buffer, buf, count); 190 if (missing == 0) 191 status = spidev_sync_write(spidev, count); 192 else 193 status = -EFAULT; 194 mutex_unlock(&spidev->buf_lock); 195 196 return status; 197 } 198 199 static int spidev_message(struct spidev_data *spidev, 200 struct spi_ioc_transfer *u_xfers, unsigned n_xfers) 201 { 202 struct spi_message msg; 203 struct spi_transfer *k_xfers; 204 struct spi_transfer *k_tmp; 205 struct spi_ioc_transfer *u_tmp; 206 unsigned n, total, tx_total, rx_total; 207 u8 *tx_buf, *rx_buf; 208 int status = -EFAULT; 209 210 spi_message_init(&msg); 211 k_xfers = kcalloc(n_xfers, sizeof(*k_tmp), GFP_KERNEL); 212 if (k_xfers == NULL) 213 return -ENOMEM; 214 215 /* Construct spi_message, copying any tx data to bounce buffer. 216 * We walk the array of user-provided transfers, using each one 217 * to initialize a kernel version of the same transfer. 218 */ 219 tx_buf = spidev->tx_buffer; 220 rx_buf = spidev->rx_buffer; 221 total = 0; 222 tx_total = 0; 223 rx_total = 0; 224 for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers; 225 n; 226 n--, k_tmp++, u_tmp++) { 227 /* Ensure that also following allocations from rx_buf/tx_buf will meet 228 * DMA alignment requirements. 229 */ 230 unsigned int len_aligned = ALIGN(u_tmp->len, ARCH_KMALLOC_MINALIGN); 231 232 k_tmp->len = u_tmp->len; 233 234 total += k_tmp->len; 235 /* Since the function returns the total length of transfers 236 * on success, restrict the total to positive int values to 237 * avoid the return value looking like an error. Also check 238 * each transfer length to avoid arithmetic overflow. 239 */ 240 if (total > INT_MAX || k_tmp->len > INT_MAX) { 241 status = -EMSGSIZE; 242 goto done; 243 } 244 245 if (u_tmp->rx_buf) { 246 /* this transfer needs space in RX bounce buffer */ 247 rx_total += len_aligned; 248 if (rx_total > bufsiz) { 249 status = -EMSGSIZE; 250 goto done; 251 } 252 k_tmp->rx_buf = rx_buf; 253 rx_buf += len_aligned; 254 } 255 if (u_tmp->tx_buf) { 256 /* this transfer needs space in TX bounce buffer */ 257 tx_total += len_aligned; 258 if (tx_total > bufsiz) { 259 status = -EMSGSIZE; 260 goto done; 261 } 262 k_tmp->tx_buf = tx_buf; 263 if (copy_from_user(tx_buf, (const u8 __user *) 264 (uintptr_t) u_tmp->tx_buf, 265 u_tmp->len)) 266 goto done; 267 tx_buf += len_aligned; 268 } 269 270 k_tmp->cs_change = !!u_tmp->cs_change; 271 k_tmp->tx_nbits = u_tmp->tx_nbits; 272 k_tmp->rx_nbits = u_tmp->rx_nbits; 273 k_tmp->bits_per_word = u_tmp->bits_per_word; 274 k_tmp->delay.value = u_tmp->delay_usecs; 275 k_tmp->delay.unit = SPI_DELAY_UNIT_USECS; 276 k_tmp->speed_hz = u_tmp->speed_hz; 277 k_tmp->word_delay.value = u_tmp->word_delay_usecs; 278 k_tmp->word_delay.unit = SPI_DELAY_UNIT_USECS; 279 if (!k_tmp->speed_hz) 280 k_tmp->speed_hz = spidev->speed_hz; 281 #ifdef VERBOSE 282 dev_dbg(&spidev->spi->dev, 283 " xfer len %u %s%s%s%dbits %u usec %u usec %uHz\n", 284 k_tmp->len, 285 k_tmp->rx_buf ? "rx " : "", 286 k_tmp->tx_buf ? "tx " : "", 287 k_tmp->cs_change ? "cs " : "", 288 k_tmp->bits_per_word ? : spidev->spi->bits_per_word, 289 k_tmp->delay.value, 290 k_tmp->word_delay.value, 291 k_tmp->speed_hz ? : spidev->spi->max_speed_hz); 292 #endif 293 spi_message_add_tail(k_tmp, &msg); 294 } 295 296 status = spidev_sync(spidev, &msg); 297 if (status < 0) 298 goto done; 299 300 /* copy any rx data out of bounce buffer */ 301 for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers; 302 n; 303 n--, k_tmp++, u_tmp++) { 304 if (u_tmp->rx_buf) { 305 if (copy_to_user((u8 __user *) 306 (uintptr_t) u_tmp->rx_buf, k_tmp->rx_buf, 307 u_tmp->len)) { 308 status = -EFAULT; 309 goto done; 310 } 311 } 312 } 313 status = total; 314 315 done: 316 kfree(k_xfers); 317 return status; 318 } 319 320 static struct spi_ioc_transfer * 321 spidev_get_ioc_message(unsigned int cmd, struct spi_ioc_transfer __user *u_ioc, 322 unsigned *n_ioc) 323 { 324 u32 tmp; 325 326 /* Check type, command number and direction */ 327 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC 328 || _IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0)) 329 || _IOC_DIR(cmd) != _IOC_WRITE) 330 return ERR_PTR(-ENOTTY); 331 332 tmp = _IOC_SIZE(cmd); 333 if ((tmp % sizeof(struct spi_ioc_transfer)) != 0) 334 return ERR_PTR(-EINVAL); 335 *n_ioc = tmp / sizeof(struct spi_ioc_transfer); 336 if (*n_ioc == 0) 337 return NULL; 338 339 /* copy into scratch area */ 340 return memdup_user(u_ioc, tmp); 341 } 342 343 static long 344 spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) 345 { 346 int retval = 0; 347 struct spidev_data *spidev; 348 struct spi_device *spi; 349 u32 tmp; 350 unsigned n_ioc; 351 struct spi_ioc_transfer *ioc; 352 353 /* Check type and command number */ 354 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC) 355 return -ENOTTY; 356 357 /* guard against device removal before, or while, 358 * we issue this ioctl. 359 */ 360 spidev = filp->private_data; 361 spin_lock_irq(&spidev->spi_lock); 362 spi = spi_dev_get(spidev->spi); 363 spin_unlock_irq(&spidev->spi_lock); 364 365 if (spi == NULL) 366 return -ESHUTDOWN; 367 368 /* use the buffer lock here for triple duty: 369 * - prevent I/O (from us) so calling spi_setup() is safe; 370 * - prevent concurrent SPI_IOC_WR_* from morphing 371 * data fields while SPI_IOC_RD_* reads them; 372 * - SPI_IOC_MESSAGE needs the buffer locked "normally". 373 */ 374 mutex_lock(&spidev->buf_lock); 375 376 switch (cmd) { 377 /* read requests */ 378 case SPI_IOC_RD_MODE: 379 retval = put_user(spi->mode & SPI_MODE_MASK, 380 (__u8 __user *)arg); 381 break; 382 case SPI_IOC_RD_MODE32: 383 retval = put_user(spi->mode & SPI_MODE_MASK, 384 (__u32 __user *)arg); 385 break; 386 case SPI_IOC_RD_LSB_FIRST: 387 retval = put_user((spi->mode & SPI_LSB_FIRST) ? 1 : 0, 388 (__u8 __user *)arg); 389 break; 390 case SPI_IOC_RD_BITS_PER_WORD: 391 retval = put_user(spi->bits_per_word, (__u8 __user *)arg); 392 break; 393 case SPI_IOC_RD_MAX_SPEED_HZ: 394 retval = put_user(spidev->speed_hz, (__u32 __user *)arg); 395 break; 396 397 /* write requests */ 398 case SPI_IOC_WR_MODE: 399 case SPI_IOC_WR_MODE32: 400 if (cmd == SPI_IOC_WR_MODE) 401 retval = get_user(tmp, (u8 __user *)arg); 402 else 403 retval = get_user(tmp, (u32 __user *)arg); 404 if (retval == 0) { 405 struct spi_controller *ctlr = spi->controller; 406 u32 save = spi->mode; 407 408 if (tmp & ~SPI_MODE_MASK) { 409 retval = -EINVAL; 410 break; 411 } 412 413 if (ctlr->use_gpio_descriptors && ctlr->cs_gpiods && 414 ctlr->cs_gpiods[spi->chip_select]) 415 tmp |= SPI_CS_HIGH; 416 417 tmp |= spi->mode & ~SPI_MODE_MASK; 418 spi->mode = tmp & SPI_MODE_USER_MASK; 419 retval = spi_setup(spi); 420 if (retval < 0) 421 spi->mode = save; 422 else 423 dev_dbg(&spi->dev, "spi mode %x\n", tmp); 424 } 425 break; 426 case SPI_IOC_WR_LSB_FIRST: 427 retval = get_user(tmp, (__u8 __user *)arg); 428 if (retval == 0) { 429 u32 save = spi->mode; 430 431 if (tmp) 432 spi->mode |= SPI_LSB_FIRST; 433 else 434 spi->mode &= ~SPI_LSB_FIRST; 435 retval = spi_setup(spi); 436 if (retval < 0) 437 spi->mode = save; 438 else 439 dev_dbg(&spi->dev, "%csb first\n", 440 tmp ? 'l' : 'm'); 441 } 442 break; 443 case SPI_IOC_WR_BITS_PER_WORD: 444 retval = get_user(tmp, (__u8 __user *)arg); 445 if (retval == 0) { 446 u8 save = spi->bits_per_word; 447 448 spi->bits_per_word = tmp; 449 retval = spi_setup(spi); 450 if (retval < 0) 451 spi->bits_per_word = save; 452 else 453 dev_dbg(&spi->dev, "%d bits per word\n", tmp); 454 } 455 break; 456 case SPI_IOC_WR_MAX_SPEED_HZ: 457 retval = get_user(tmp, (__u32 __user *)arg); 458 if (retval == 0) { 459 u32 save = spi->max_speed_hz; 460 461 spi->max_speed_hz = tmp; 462 retval = spi_setup(spi); 463 if (retval == 0) { 464 spidev->speed_hz = tmp; 465 dev_dbg(&spi->dev, "%d Hz (max)\n", 466 spidev->speed_hz); 467 } 468 spi->max_speed_hz = save; 469 } 470 break; 471 472 default: 473 /* segmented and/or full-duplex I/O request */ 474 /* Check message and copy into scratch area */ 475 ioc = spidev_get_ioc_message(cmd, 476 (struct spi_ioc_transfer __user *)arg, &n_ioc); 477 if (IS_ERR(ioc)) { 478 retval = PTR_ERR(ioc); 479 break; 480 } 481 if (!ioc) 482 break; /* n_ioc is also 0 */ 483 484 /* translate to spi_message, execute */ 485 retval = spidev_message(spidev, ioc, n_ioc); 486 kfree(ioc); 487 break; 488 } 489 490 mutex_unlock(&spidev->buf_lock); 491 spi_dev_put(spi); 492 return retval; 493 } 494 495 #ifdef CONFIG_COMPAT 496 static long 497 spidev_compat_ioc_message(struct file *filp, unsigned int cmd, 498 unsigned long arg) 499 { 500 struct spi_ioc_transfer __user *u_ioc; 501 int retval = 0; 502 struct spidev_data *spidev; 503 struct spi_device *spi; 504 unsigned n_ioc, n; 505 struct spi_ioc_transfer *ioc; 506 507 u_ioc = (struct spi_ioc_transfer __user *) compat_ptr(arg); 508 509 /* guard against device removal before, or while, 510 * we issue this ioctl. 511 */ 512 spidev = filp->private_data; 513 spin_lock_irq(&spidev->spi_lock); 514 spi = spi_dev_get(spidev->spi); 515 spin_unlock_irq(&spidev->spi_lock); 516 517 if (spi == NULL) 518 return -ESHUTDOWN; 519 520 /* SPI_IOC_MESSAGE needs the buffer locked "normally" */ 521 mutex_lock(&spidev->buf_lock); 522 523 /* Check message and copy into scratch area */ 524 ioc = spidev_get_ioc_message(cmd, u_ioc, &n_ioc); 525 if (IS_ERR(ioc)) { 526 retval = PTR_ERR(ioc); 527 goto done; 528 } 529 if (!ioc) 530 goto done; /* n_ioc is also 0 */ 531 532 /* Convert buffer pointers */ 533 for (n = 0; n < n_ioc; n++) { 534 ioc[n].rx_buf = (uintptr_t) compat_ptr(ioc[n].rx_buf); 535 ioc[n].tx_buf = (uintptr_t) compat_ptr(ioc[n].tx_buf); 536 } 537 538 /* translate to spi_message, execute */ 539 retval = spidev_message(spidev, ioc, n_ioc); 540 kfree(ioc); 541 542 done: 543 mutex_unlock(&spidev->buf_lock); 544 spi_dev_put(spi); 545 return retval; 546 } 547 548 static long 549 spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) 550 { 551 if (_IOC_TYPE(cmd) == SPI_IOC_MAGIC 552 && _IOC_NR(cmd) == _IOC_NR(SPI_IOC_MESSAGE(0)) 553 && _IOC_DIR(cmd) == _IOC_WRITE) 554 return spidev_compat_ioc_message(filp, cmd, arg); 555 556 return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg)); 557 } 558 #else 559 #define spidev_compat_ioctl NULL 560 #endif /* CONFIG_COMPAT */ 561 562 static int spidev_open(struct inode *inode, struct file *filp) 563 { 564 struct spidev_data *spidev; 565 int status = -ENXIO; 566 567 mutex_lock(&device_list_lock); 568 569 list_for_each_entry(spidev, &device_list, device_entry) { 570 if (spidev->devt == inode->i_rdev) { 571 status = 0; 572 break; 573 } 574 } 575 576 if (status) { 577 pr_debug("spidev: nothing for minor %d\n", iminor(inode)); 578 goto err_find_dev; 579 } 580 581 if (!spidev->tx_buffer) { 582 spidev->tx_buffer = kmalloc(bufsiz, GFP_KERNEL); 583 if (!spidev->tx_buffer) { 584 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n"); 585 status = -ENOMEM; 586 goto err_find_dev; 587 } 588 } 589 590 if (!spidev->rx_buffer) { 591 spidev->rx_buffer = kmalloc(bufsiz, GFP_KERNEL); 592 if (!spidev->rx_buffer) { 593 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n"); 594 status = -ENOMEM; 595 goto err_alloc_rx_buf; 596 } 597 } 598 599 spidev->users++; 600 filp->private_data = spidev; 601 stream_open(inode, filp); 602 603 mutex_unlock(&device_list_lock); 604 return 0; 605 606 err_alloc_rx_buf: 607 kfree(spidev->tx_buffer); 608 spidev->tx_buffer = NULL; 609 err_find_dev: 610 mutex_unlock(&device_list_lock); 611 return status; 612 } 613 614 static int spidev_release(struct inode *inode, struct file *filp) 615 { 616 struct spidev_data *spidev; 617 int dofree; 618 619 mutex_lock(&device_list_lock); 620 spidev = filp->private_data; 621 filp->private_data = NULL; 622 623 spin_lock_irq(&spidev->spi_lock); 624 /* ... after we unbound from the underlying device? */ 625 dofree = (spidev->spi == NULL); 626 spin_unlock_irq(&spidev->spi_lock); 627 628 /* last close? */ 629 spidev->users--; 630 if (!spidev->users) { 631 632 kfree(spidev->tx_buffer); 633 spidev->tx_buffer = NULL; 634 635 kfree(spidev->rx_buffer); 636 spidev->rx_buffer = NULL; 637 638 if (dofree) 639 kfree(spidev); 640 else 641 spidev->speed_hz = spidev->spi->max_speed_hz; 642 } 643 #ifdef CONFIG_SPI_SLAVE 644 if (!dofree) 645 spi_slave_abort(spidev->spi); 646 #endif 647 mutex_unlock(&device_list_lock); 648 649 return 0; 650 } 651 652 static const struct file_operations spidev_fops = { 653 .owner = THIS_MODULE, 654 /* REVISIT switch to aio primitives, so that userspace 655 * gets more complete API coverage. It'll simplify things 656 * too, except for the locking. 657 */ 658 .write = spidev_write, 659 .read = spidev_read, 660 .unlocked_ioctl = spidev_ioctl, 661 .compat_ioctl = spidev_compat_ioctl, 662 .open = spidev_open, 663 .release = spidev_release, 664 .llseek = no_llseek, 665 }; 666 667 /*-------------------------------------------------------------------------*/ 668 669 /* The main reason to have this class is to make mdev/udev create the 670 * /dev/spidevB.C character device nodes exposing our userspace API. 671 * It also simplifies memory management. 672 */ 673 674 static struct class *spidev_class; 675 676 static const struct spi_device_id spidev_spi_ids[] = { 677 { .name = "dh2228fv" }, 678 { .name = "ltc2488" }, 679 { .name = "sx1301" }, 680 { .name = "bk4" }, 681 { .name = "dhcom-board" }, 682 { .name = "m53cpld" }, 683 { .name = "spi-petra" }, 684 { .name = "spi-authenta" }, 685 {}, 686 }; 687 MODULE_DEVICE_TABLE(spi, spidev_spi_ids); 688 689 #ifdef CONFIG_OF 690 static const struct of_device_id spidev_dt_ids[] = { 691 { .compatible = "rohm,dh2228fv" }, 692 { .compatible = "lineartechnology,ltc2488" }, 693 { .compatible = "semtech,sx1301" }, 694 { .compatible = "lwn,bk4" }, 695 { .compatible = "dh,dhcom-board" }, 696 { .compatible = "menlo,m53cpld" }, 697 { .compatible = "cisco,spi-petra" }, 698 { .compatible = "micron,spi-authenta" }, 699 {}, 700 }; 701 MODULE_DEVICE_TABLE(of, spidev_dt_ids); 702 #endif 703 704 #ifdef CONFIG_ACPI 705 706 /* Dummy SPI devices not to be used in production systems */ 707 #define SPIDEV_ACPI_DUMMY 1 708 709 static const struct acpi_device_id spidev_acpi_ids[] = { 710 /* 711 * The ACPI SPT000* devices are only meant for development and 712 * testing. Systems used in production should have a proper ACPI 713 * description of the connected peripheral and they should also use 714 * a proper driver instead of poking directly to the SPI bus. 715 */ 716 { "SPT0001", SPIDEV_ACPI_DUMMY }, 717 { "SPT0002", SPIDEV_ACPI_DUMMY }, 718 { "SPT0003", SPIDEV_ACPI_DUMMY }, 719 {}, 720 }; 721 MODULE_DEVICE_TABLE(acpi, spidev_acpi_ids); 722 723 static void spidev_probe_acpi(struct spi_device *spi) 724 { 725 const struct acpi_device_id *id; 726 727 if (!has_acpi_companion(&spi->dev)) 728 return; 729 730 id = acpi_match_device(spidev_acpi_ids, &spi->dev); 731 if (WARN_ON(!id)) 732 return; 733 734 if (id->driver_data == SPIDEV_ACPI_DUMMY) 735 dev_warn(&spi->dev, "do not use this driver in production systems!\n"); 736 } 737 #else 738 static inline void spidev_probe_acpi(struct spi_device *spi) {} 739 #endif 740 741 /*-------------------------------------------------------------------------*/ 742 743 static int spidev_probe(struct spi_device *spi) 744 { 745 struct spidev_data *spidev; 746 int status; 747 unsigned long minor; 748 749 /* 750 * spidev should never be referenced in DT without a specific 751 * compatible string, it is a Linux implementation thing 752 * rather than a description of the hardware. 753 */ 754 if (spi->dev.of_node && of_device_is_compatible(spi->dev.of_node, "spidev")) { 755 dev_err(&spi->dev, "spidev listed directly in DT is not supported\n"); 756 return -EINVAL; 757 } 758 759 spidev_probe_acpi(spi); 760 761 /* Allocate driver data */ 762 spidev = kzalloc(sizeof(*spidev), GFP_KERNEL); 763 if (!spidev) 764 return -ENOMEM; 765 766 /* Initialize the driver data */ 767 spidev->spi = spi; 768 spin_lock_init(&spidev->spi_lock); 769 mutex_init(&spidev->buf_lock); 770 771 INIT_LIST_HEAD(&spidev->device_entry); 772 773 /* If we can allocate a minor number, hook up this device. 774 * Reusing minors is fine so long as udev or mdev is working. 775 */ 776 mutex_lock(&device_list_lock); 777 minor = find_first_zero_bit(minors, N_SPI_MINORS); 778 if (minor < N_SPI_MINORS) { 779 struct device *dev; 780 781 spidev->devt = MKDEV(SPIDEV_MAJOR, minor); 782 dev = device_create(spidev_class, &spi->dev, spidev->devt, 783 spidev, "spidev%d.%d", 784 spi->master->bus_num, spi->chip_select); 785 status = PTR_ERR_OR_ZERO(dev); 786 } else { 787 dev_dbg(&spi->dev, "no minor number available!\n"); 788 status = -ENODEV; 789 } 790 if (status == 0) { 791 set_bit(minor, minors); 792 list_add(&spidev->device_entry, &device_list); 793 } 794 mutex_unlock(&device_list_lock); 795 796 spidev->speed_hz = spi->max_speed_hz; 797 798 if (status == 0) 799 spi_set_drvdata(spi, spidev); 800 else 801 kfree(spidev); 802 803 return status; 804 } 805 806 static int spidev_remove(struct spi_device *spi) 807 { 808 struct spidev_data *spidev = spi_get_drvdata(spi); 809 810 /* prevent new opens */ 811 mutex_lock(&device_list_lock); 812 /* make sure ops on existing fds can abort cleanly */ 813 spin_lock_irq(&spidev->spi_lock); 814 spidev->spi = NULL; 815 spin_unlock_irq(&spidev->spi_lock); 816 817 list_del(&spidev->device_entry); 818 device_destroy(spidev_class, spidev->devt); 819 clear_bit(MINOR(spidev->devt), minors); 820 if (spidev->users == 0) 821 kfree(spidev); 822 mutex_unlock(&device_list_lock); 823 824 return 0; 825 } 826 827 static struct spi_driver spidev_spi_driver = { 828 .driver = { 829 .name = "spidev", 830 .of_match_table = of_match_ptr(spidev_dt_ids), 831 .acpi_match_table = ACPI_PTR(spidev_acpi_ids), 832 }, 833 .probe = spidev_probe, 834 .remove = spidev_remove, 835 .id_table = spidev_spi_ids, 836 837 /* NOTE: suspend/resume methods are not necessary here. 838 * We don't do anything except pass the requests to/from 839 * the underlying controller. The refrigerator handles 840 * most issues; the controller driver handles the rest. 841 */ 842 }; 843 844 /*-------------------------------------------------------------------------*/ 845 846 static int __init spidev_init(void) 847 { 848 int status; 849 850 /* Claim our 256 reserved device numbers. Then register a class 851 * that will key udev/mdev to add/remove /dev nodes. Last, register 852 * the driver which manages those device numbers. 853 */ 854 BUILD_BUG_ON(N_SPI_MINORS > 256); 855 status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops); 856 if (status < 0) 857 return status; 858 859 spidev_class = class_create(THIS_MODULE, "spidev"); 860 if (IS_ERR(spidev_class)) { 861 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name); 862 return PTR_ERR(spidev_class); 863 } 864 865 status = spi_register_driver(&spidev_spi_driver); 866 if (status < 0) { 867 class_destroy(spidev_class); 868 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name); 869 } 870 return status; 871 } 872 module_init(spidev_init); 873 874 static void __exit spidev_exit(void) 875 { 876 spi_unregister_driver(&spidev_spi_driver); 877 class_destroy(spidev_class); 878 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name); 879 } 880 module_exit(spidev_exit); 881 882 MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>"); 883 MODULE_DESCRIPTION("User mode SPI device interface"); 884 MODULE_LICENSE("GPL"); 885 MODULE_ALIAS("spi:spidev"); 886