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_CPHA | SPI_CPOL | 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_RX_DUAL | SPI_RX_QUAD) 66 67 struct spidev_data { 68 dev_t devt; 69 spinlock_t spi_lock; 70 struct spi_device *spi; 71 struct list_head device_entry; 72 73 /* TX/RX buffers are NULL unless this device is open (users > 0) */ 74 struct mutex buf_lock; 75 unsigned users; 76 u8 *tx_buffer; 77 u8 *rx_buffer; 78 u32 speed_hz; 79 }; 80 81 static LIST_HEAD(device_list); 82 static DEFINE_MUTEX(device_list_lock); 83 84 static unsigned bufsiz = 4096; 85 module_param(bufsiz, uint, S_IRUGO); 86 MODULE_PARM_DESC(bufsiz, "data bytes in biggest supported SPI message"); 87 88 /*-------------------------------------------------------------------------*/ 89 90 static ssize_t 91 spidev_sync(struct spidev_data *spidev, struct spi_message *message) 92 { 93 int status; 94 struct spi_device *spi; 95 96 spin_lock_irq(&spidev->spi_lock); 97 spi = spidev->spi; 98 spin_unlock_irq(&spidev->spi_lock); 99 100 if (spi == NULL) 101 status = -ESHUTDOWN; 102 else 103 status = spi_sync(spi, message); 104 105 if (status == 0) 106 status = message->actual_length; 107 108 return status; 109 } 110 111 static inline ssize_t 112 spidev_sync_write(struct spidev_data *spidev, size_t len) 113 { 114 struct spi_transfer t = { 115 .tx_buf = spidev->tx_buffer, 116 .len = len, 117 .speed_hz = spidev->speed_hz, 118 }; 119 struct spi_message m; 120 121 spi_message_init(&m); 122 spi_message_add_tail(&t, &m); 123 return spidev_sync(spidev, &m); 124 } 125 126 static inline ssize_t 127 spidev_sync_read(struct spidev_data *spidev, size_t len) 128 { 129 struct spi_transfer t = { 130 .rx_buf = spidev->rx_buffer, 131 .len = len, 132 .speed_hz = spidev->speed_hz, 133 }; 134 struct spi_message m; 135 136 spi_message_init(&m); 137 spi_message_add_tail(&t, &m); 138 return spidev_sync(spidev, &m); 139 } 140 141 /*-------------------------------------------------------------------------*/ 142 143 /* Read-only message with current device setup */ 144 static ssize_t 145 spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos) 146 { 147 struct spidev_data *spidev; 148 ssize_t status = 0; 149 150 /* chipselect only toggles at start or end of operation */ 151 if (count > bufsiz) 152 return -EMSGSIZE; 153 154 spidev = filp->private_data; 155 156 mutex_lock(&spidev->buf_lock); 157 status = spidev_sync_read(spidev, count); 158 if (status > 0) { 159 unsigned long missing; 160 161 missing = copy_to_user(buf, spidev->rx_buffer, status); 162 if (missing == status) 163 status = -EFAULT; 164 else 165 status = status - missing; 166 } 167 mutex_unlock(&spidev->buf_lock); 168 169 return status; 170 } 171 172 /* Write-only message with current device setup */ 173 static ssize_t 174 spidev_write(struct file *filp, const char __user *buf, 175 size_t count, loff_t *f_pos) 176 { 177 struct spidev_data *spidev; 178 ssize_t status = 0; 179 unsigned long missing; 180 181 /* chipselect only toggles at start or end of operation */ 182 if (count > bufsiz) 183 return -EMSGSIZE; 184 185 spidev = filp->private_data; 186 187 mutex_lock(&spidev->buf_lock); 188 missing = copy_from_user(spidev->tx_buffer, buf, count); 189 if (missing == 0) 190 status = spidev_sync_write(spidev, count); 191 else 192 status = -EFAULT; 193 mutex_unlock(&spidev->buf_lock); 194 195 return status; 196 } 197 198 static int spidev_message(struct spidev_data *spidev, 199 struct spi_ioc_transfer *u_xfers, unsigned n_xfers) 200 { 201 struct spi_message msg; 202 struct spi_transfer *k_xfers; 203 struct spi_transfer *k_tmp; 204 struct spi_ioc_transfer *u_tmp; 205 unsigned n, total, tx_total, rx_total; 206 u8 *tx_buf, *rx_buf; 207 int status = -EFAULT; 208 209 spi_message_init(&msg); 210 k_xfers = kcalloc(n_xfers, sizeof(*k_tmp), GFP_KERNEL); 211 if (k_xfers == NULL) 212 return -ENOMEM; 213 214 /* Construct spi_message, copying any tx data to bounce buffer. 215 * We walk the array of user-provided transfers, using each one 216 * to initialize a kernel version of the same transfer. 217 */ 218 tx_buf = spidev->tx_buffer; 219 rx_buf = spidev->rx_buffer; 220 total = 0; 221 tx_total = 0; 222 rx_total = 0; 223 for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers; 224 n; 225 n--, k_tmp++, u_tmp++) { 226 k_tmp->len = u_tmp->len; 227 228 total += k_tmp->len; 229 /* Since the function returns the total length of transfers 230 * on success, restrict the total to positive int values to 231 * avoid the return value looking like an error. Also check 232 * each transfer length to avoid arithmetic overflow. 233 */ 234 if (total > INT_MAX || k_tmp->len > INT_MAX) { 235 status = -EMSGSIZE; 236 goto done; 237 } 238 239 if (u_tmp->rx_buf) { 240 /* this transfer needs space in RX bounce buffer */ 241 rx_total += k_tmp->len; 242 if (rx_total > bufsiz) { 243 status = -EMSGSIZE; 244 goto done; 245 } 246 k_tmp->rx_buf = rx_buf; 247 rx_buf += k_tmp->len; 248 } 249 if (u_tmp->tx_buf) { 250 /* this transfer needs space in TX bounce buffer */ 251 tx_total += k_tmp->len; 252 if (tx_total > bufsiz) { 253 status = -EMSGSIZE; 254 goto done; 255 } 256 k_tmp->tx_buf = tx_buf; 257 if (copy_from_user(tx_buf, (const u8 __user *) 258 (uintptr_t) u_tmp->tx_buf, 259 u_tmp->len)) 260 goto done; 261 tx_buf += k_tmp->len; 262 } 263 264 k_tmp->cs_change = !!u_tmp->cs_change; 265 k_tmp->tx_nbits = u_tmp->tx_nbits; 266 k_tmp->rx_nbits = u_tmp->rx_nbits; 267 k_tmp->bits_per_word = u_tmp->bits_per_word; 268 k_tmp->delay_usecs = u_tmp->delay_usecs; 269 k_tmp->speed_hz = u_tmp->speed_hz; 270 k_tmp->word_delay_usecs = u_tmp->word_delay_usecs; 271 if (!k_tmp->speed_hz) 272 k_tmp->speed_hz = spidev->speed_hz; 273 #ifdef VERBOSE 274 dev_dbg(&spidev->spi->dev, 275 " xfer len %u %s%s%s%dbits %u usec %u usec %uHz\n", 276 u_tmp->len, 277 u_tmp->rx_buf ? "rx " : "", 278 u_tmp->tx_buf ? "tx " : "", 279 u_tmp->cs_change ? "cs " : "", 280 u_tmp->bits_per_word ? : spidev->spi->bits_per_word, 281 u_tmp->delay_usecs, 282 u_tmp->word_delay_usecs, 283 u_tmp->speed_hz ? : spidev->spi->max_speed_hz); 284 #endif 285 spi_message_add_tail(k_tmp, &msg); 286 } 287 288 status = spidev_sync(spidev, &msg); 289 if (status < 0) 290 goto done; 291 292 /* copy any rx data out of bounce buffer */ 293 rx_buf = spidev->rx_buffer; 294 for (n = n_xfers, u_tmp = u_xfers; n; n--, u_tmp++) { 295 if (u_tmp->rx_buf) { 296 if (copy_to_user((u8 __user *) 297 (uintptr_t) u_tmp->rx_buf, rx_buf, 298 u_tmp->len)) { 299 status = -EFAULT; 300 goto done; 301 } 302 rx_buf += u_tmp->len; 303 } 304 } 305 status = total; 306 307 done: 308 kfree(k_xfers); 309 return status; 310 } 311 312 static struct spi_ioc_transfer * 313 spidev_get_ioc_message(unsigned int cmd, struct spi_ioc_transfer __user *u_ioc, 314 unsigned *n_ioc) 315 { 316 u32 tmp; 317 318 /* Check type, command number and direction */ 319 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC 320 || _IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0)) 321 || _IOC_DIR(cmd) != _IOC_WRITE) 322 return ERR_PTR(-ENOTTY); 323 324 tmp = _IOC_SIZE(cmd); 325 if ((tmp % sizeof(struct spi_ioc_transfer)) != 0) 326 return ERR_PTR(-EINVAL); 327 *n_ioc = tmp / sizeof(struct spi_ioc_transfer); 328 if (*n_ioc == 0) 329 return NULL; 330 331 /* copy into scratch area */ 332 return memdup_user(u_ioc, tmp); 333 } 334 335 static long 336 spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) 337 { 338 int retval = 0; 339 struct spidev_data *spidev; 340 struct spi_device *spi; 341 u32 tmp; 342 unsigned n_ioc; 343 struct spi_ioc_transfer *ioc; 344 345 /* Check type and command number */ 346 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC) 347 return -ENOTTY; 348 349 /* guard against device removal before, or while, 350 * we issue this ioctl. 351 */ 352 spidev = filp->private_data; 353 spin_lock_irq(&spidev->spi_lock); 354 spi = spi_dev_get(spidev->spi); 355 spin_unlock_irq(&spidev->spi_lock); 356 357 if (spi == NULL) 358 return -ESHUTDOWN; 359 360 /* use the buffer lock here for triple duty: 361 * - prevent I/O (from us) so calling spi_setup() is safe; 362 * - prevent concurrent SPI_IOC_WR_* from morphing 363 * data fields while SPI_IOC_RD_* reads them; 364 * - SPI_IOC_MESSAGE needs the buffer locked "normally". 365 */ 366 mutex_lock(&spidev->buf_lock); 367 368 switch (cmd) { 369 /* read requests */ 370 case SPI_IOC_RD_MODE: 371 retval = put_user(spi->mode & SPI_MODE_MASK, 372 (__u8 __user *)arg); 373 break; 374 case SPI_IOC_RD_MODE32: 375 retval = put_user(spi->mode & SPI_MODE_MASK, 376 (__u32 __user *)arg); 377 break; 378 case SPI_IOC_RD_LSB_FIRST: 379 retval = put_user((spi->mode & SPI_LSB_FIRST) ? 1 : 0, 380 (__u8 __user *)arg); 381 break; 382 case SPI_IOC_RD_BITS_PER_WORD: 383 retval = put_user(spi->bits_per_word, (__u8 __user *)arg); 384 break; 385 case SPI_IOC_RD_MAX_SPEED_HZ: 386 retval = put_user(spidev->speed_hz, (__u32 __user *)arg); 387 break; 388 389 /* write requests */ 390 case SPI_IOC_WR_MODE: 391 case SPI_IOC_WR_MODE32: 392 if (cmd == SPI_IOC_WR_MODE) 393 retval = get_user(tmp, (u8 __user *)arg); 394 else 395 retval = get_user(tmp, (u32 __user *)arg); 396 if (retval == 0) { 397 u32 save = spi->mode; 398 399 if (tmp & ~SPI_MODE_MASK) { 400 retval = -EINVAL; 401 break; 402 } 403 404 tmp |= spi->mode & ~SPI_MODE_MASK; 405 spi->mode = (u16)tmp; 406 retval = spi_setup(spi); 407 if (retval < 0) 408 spi->mode = save; 409 else 410 dev_dbg(&spi->dev, "spi mode %x\n", tmp); 411 } 412 break; 413 case SPI_IOC_WR_LSB_FIRST: 414 retval = get_user(tmp, (__u8 __user *)arg); 415 if (retval == 0) { 416 u32 save = spi->mode; 417 418 if (tmp) 419 spi->mode |= SPI_LSB_FIRST; 420 else 421 spi->mode &= ~SPI_LSB_FIRST; 422 retval = spi_setup(spi); 423 if (retval < 0) 424 spi->mode = save; 425 else 426 dev_dbg(&spi->dev, "%csb first\n", 427 tmp ? 'l' : 'm'); 428 } 429 break; 430 case SPI_IOC_WR_BITS_PER_WORD: 431 retval = get_user(tmp, (__u8 __user *)arg); 432 if (retval == 0) { 433 u8 save = spi->bits_per_word; 434 435 spi->bits_per_word = tmp; 436 retval = spi_setup(spi); 437 if (retval < 0) 438 spi->bits_per_word = save; 439 else 440 dev_dbg(&spi->dev, "%d bits per word\n", tmp); 441 } 442 break; 443 case SPI_IOC_WR_MAX_SPEED_HZ: 444 retval = get_user(tmp, (__u32 __user *)arg); 445 if (retval == 0) { 446 u32 save = spi->max_speed_hz; 447 448 spi->max_speed_hz = tmp; 449 retval = spi_setup(spi); 450 if (retval >= 0) 451 spidev->speed_hz = tmp; 452 else 453 dev_dbg(&spi->dev, "%d Hz (max)\n", tmp); 454 spi->max_speed_hz = save; 455 } 456 break; 457 458 default: 459 /* segmented and/or full-duplex I/O request */ 460 /* Check message and copy into scratch area */ 461 ioc = spidev_get_ioc_message(cmd, 462 (struct spi_ioc_transfer __user *)arg, &n_ioc); 463 if (IS_ERR(ioc)) { 464 retval = PTR_ERR(ioc); 465 break; 466 } 467 if (!ioc) 468 break; /* n_ioc is also 0 */ 469 470 /* translate to spi_message, execute */ 471 retval = spidev_message(spidev, ioc, n_ioc); 472 kfree(ioc); 473 break; 474 } 475 476 mutex_unlock(&spidev->buf_lock); 477 spi_dev_put(spi); 478 return retval; 479 } 480 481 #ifdef CONFIG_COMPAT 482 static long 483 spidev_compat_ioc_message(struct file *filp, unsigned int cmd, 484 unsigned long arg) 485 { 486 struct spi_ioc_transfer __user *u_ioc; 487 int retval = 0; 488 struct spidev_data *spidev; 489 struct spi_device *spi; 490 unsigned n_ioc, n; 491 struct spi_ioc_transfer *ioc; 492 493 u_ioc = (struct spi_ioc_transfer __user *) compat_ptr(arg); 494 495 /* guard against device removal before, or while, 496 * we issue this ioctl. 497 */ 498 spidev = filp->private_data; 499 spin_lock_irq(&spidev->spi_lock); 500 spi = spi_dev_get(spidev->spi); 501 spin_unlock_irq(&spidev->spi_lock); 502 503 if (spi == NULL) 504 return -ESHUTDOWN; 505 506 /* SPI_IOC_MESSAGE needs the buffer locked "normally" */ 507 mutex_lock(&spidev->buf_lock); 508 509 /* Check message and copy into scratch area */ 510 ioc = spidev_get_ioc_message(cmd, u_ioc, &n_ioc); 511 if (IS_ERR(ioc)) { 512 retval = PTR_ERR(ioc); 513 goto done; 514 } 515 if (!ioc) 516 goto done; /* n_ioc is also 0 */ 517 518 /* Convert buffer pointers */ 519 for (n = 0; n < n_ioc; n++) { 520 ioc[n].rx_buf = (uintptr_t) compat_ptr(ioc[n].rx_buf); 521 ioc[n].tx_buf = (uintptr_t) compat_ptr(ioc[n].tx_buf); 522 } 523 524 /* translate to spi_message, execute */ 525 retval = spidev_message(spidev, ioc, n_ioc); 526 kfree(ioc); 527 528 done: 529 mutex_unlock(&spidev->buf_lock); 530 spi_dev_put(spi); 531 return retval; 532 } 533 534 static long 535 spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) 536 { 537 if (_IOC_TYPE(cmd) == SPI_IOC_MAGIC 538 && _IOC_NR(cmd) == _IOC_NR(SPI_IOC_MESSAGE(0)) 539 && _IOC_DIR(cmd) == _IOC_WRITE) 540 return spidev_compat_ioc_message(filp, cmd, arg); 541 542 return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg)); 543 } 544 #else 545 #define spidev_compat_ioctl NULL 546 #endif /* CONFIG_COMPAT */ 547 548 static int spidev_open(struct inode *inode, struct file *filp) 549 { 550 struct spidev_data *spidev; 551 int status = -ENXIO; 552 553 mutex_lock(&device_list_lock); 554 555 list_for_each_entry(spidev, &device_list, device_entry) { 556 if (spidev->devt == inode->i_rdev) { 557 status = 0; 558 break; 559 } 560 } 561 562 if (status) { 563 pr_debug("spidev: nothing for minor %d\n", iminor(inode)); 564 goto err_find_dev; 565 } 566 567 if (!spidev->tx_buffer) { 568 spidev->tx_buffer = kmalloc(bufsiz, GFP_KERNEL); 569 if (!spidev->tx_buffer) { 570 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n"); 571 status = -ENOMEM; 572 goto err_find_dev; 573 } 574 } 575 576 if (!spidev->rx_buffer) { 577 spidev->rx_buffer = kmalloc(bufsiz, GFP_KERNEL); 578 if (!spidev->rx_buffer) { 579 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n"); 580 status = -ENOMEM; 581 goto err_alloc_rx_buf; 582 } 583 } 584 585 spidev->users++; 586 filp->private_data = spidev; 587 stream_open(inode, filp); 588 589 mutex_unlock(&device_list_lock); 590 return 0; 591 592 err_alloc_rx_buf: 593 kfree(spidev->tx_buffer); 594 spidev->tx_buffer = NULL; 595 err_find_dev: 596 mutex_unlock(&device_list_lock); 597 return status; 598 } 599 600 static int spidev_release(struct inode *inode, struct file *filp) 601 { 602 struct spidev_data *spidev; 603 604 mutex_lock(&device_list_lock); 605 spidev = filp->private_data; 606 filp->private_data = NULL; 607 608 /* last close? */ 609 spidev->users--; 610 if (!spidev->users) { 611 int dofree; 612 613 kfree(spidev->tx_buffer); 614 spidev->tx_buffer = NULL; 615 616 kfree(spidev->rx_buffer); 617 spidev->rx_buffer = NULL; 618 619 spin_lock_irq(&spidev->spi_lock); 620 if (spidev->spi) 621 spidev->speed_hz = spidev->spi->max_speed_hz; 622 623 /* ... after we unbound from the underlying device? */ 624 dofree = (spidev->spi == NULL); 625 spin_unlock_irq(&spidev->spi_lock); 626 627 if (dofree) 628 kfree(spidev); 629 } 630 mutex_unlock(&device_list_lock); 631 632 return 0; 633 } 634 635 static const struct file_operations spidev_fops = { 636 .owner = THIS_MODULE, 637 /* REVISIT switch to aio primitives, so that userspace 638 * gets more complete API coverage. It'll simplify things 639 * too, except for the locking. 640 */ 641 .write = spidev_write, 642 .read = spidev_read, 643 .unlocked_ioctl = spidev_ioctl, 644 .compat_ioctl = spidev_compat_ioctl, 645 .open = spidev_open, 646 .release = spidev_release, 647 .llseek = no_llseek, 648 }; 649 650 /*-------------------------------------------------------------------------*/ 651 652 /* The main reason to have this class is to make mdev/udev create the 653 * /dev/spidevB.C character device nodes exposing our userspace API. 654 * It also simplifies memory management. 655 */ 656 657 static struct class *spidev_class; 658 659 #ifdef CONFIG_OF 660 static const struct of_device_id spidev_dt_ids[] = { 661 { .compatible = "rohm,dh2228fv" }, 662 { .compatible = "lineartechnology,ltc2488" }, 663 { .compatible = "ge,achc" }, 664 { .compatible = "semtech,sx1301" }, 665 { .compatible = "lwn,bk4" }, 666 { .compatible = "dh,dhcom-board" }, 667 { .compatible = "menlo,m53cpld" }, 668 {}, 669 }; 670 MODULE_DEVICE_TABLE(of, spidev_dt_ids); 671 #endif 672 673 #ifdef CONFIG_ACPI 674 675 /* Dummy SPI devices not to be used in production systems */ 676 #define SPIDEV_ACPI_DUMMY 1 677 678 static const struct acpi_device_id spidev_acpi_ids[] = { 679 /* 680 * The ACPI SPT000* devices are only meant for development and 681 * testing. Systems used in production should have a proper ACPI 682 * description of the connected peripheral and they should also use 683 * a proper driver instead of poking directly to the SPI bus. 684 */ 685 { "SPT0001", SPIDEV_ACPI_DUMMY }, 686 { "SPT0002", SPIDEV_ACPI_DUMMY }, 687 { "SPT0003", SPIDEV_ACPI_DUMMY }, 688 {}, 689 }; 690 MODULE_DEVICE_TABLE(acpi, spidev_acpi_ids); 691 692 static void spidev_probe_acpi(struct spi_device *spi) 693 { 694 const struct acpi_device_id *id; 695 696 if (!has_acpi_companion(&spi->dev)) 697 return; 698 699 id = acpi_match_device(spidev_acpi_ids, &spi->dev); 700 if (WARN_ON(!id)) 701 return; 702 703 if (id->driver_data == SPIDEV_ACPI_DUMMY) 704 dev_warn(&spi->dev, "do not use this driver in production systems!\n"); 705 } 706 #else 707 static inline void spidev_probe_acpi(struct spi_device *spi) {} 708 #endif 709 710 /*-------------------------------------------------------------------------*/ 711 712 static int spidev_probe(struct spi_device *spi) 713 { 714 struct spidev_data *spidev; 715 int status; 716 unsigned long minor; 717 718 /* 719 * spidev should never be referenced in DT without a specific 720 * compatible string, it is a Linux implementation thing 721 * rather than a description of the hardware. 722 */ 723 WARN(spi->dev.of_node && 724 of_device_is_compatible(spi->dev.of_node, "spidev"), 725 "%pOF: buggy DT: spidev listed directly in DT\n", spi->dev.of_node); 726 727 spidev_probe_acpi(spi); 728 729 /* Allocate driver data */ 730 spidev = kzalloc(sizeof(*spidev), GFP_KERNEL); 731 if (!spidev) 732 return -ENOMEM; 733 734 /* Initialize the driver data */ 735 spidev->spi = spi; 736 spin_lock_init(&spidev->spi_lock); 737 mutex_init(&spidev->buf_lock); 738 739 INIT_LIST_HEAD(&spidev->device_entry); 740 741 /* If we can allocate a minor number, hook up this device. 742 * Reusing minors is fine so long as udev or mdev is working. 743 */ 744 mutex_lock(&device_list_lock); 745 minor = find_first_zero_bit(minors, N_SPI_MINORS); 746 if (minor < N_SPI_MINORS) { 747 struct device *dev; 748 749 spidev->devt = MKDEV(SPIDEV_MAJOR, minor); 750 dev = device_create(spidev_class, &spi->dev, spidev->devt, 751 spidev, "spidev%d.%d", 752 spi->master->bus_num, spi->chip_select); 753 status = PTR_ERR_OR_ZERO(dev); 754 } else { 755 dev_dbg(&spi->dev, "no minor number available!\n"); 756 status = -ENODEV; 757 } 758 if (status == 0) { 759 set_bit(minor, minors); 760 list_add(&spidev->device_entry, &device_list); 761 } 762 mutex_unlock(&device_list_lock); 763 764 spidev->speed_hz = spi->max_speed_hz; 765 766 if (status == 0) 767 spi_set_drvdata(spi, spidev); 768 else 769 kfree(spidev); 770 771 return status; 772 } 773 774 static int spidev_remove(struct spi_device *spi) 775 { 776 struct spidev_data *spidev = spi_get_drvdata(spi); 777 778 /* make sure ops on existing fds can abort cleanly */ 779 spin_lock_irq(&spidev->spi_lock); 780 spidev->spi = NULL; 781 spin_unlock_irq(&spidev->spi_lock); 782 783 /* prevent new opens */ 784 mutex_lock(&device_list_lock); 785 list_del(&spidev->device_entry); 786 device_destroy(spidev_class, spidev->devt); 787 clear_bit(MINOR(spidev->devt), minors); 788 if (spidev->users == 0) 789 kfree(spidev); 790 mutex_unlock(&device_list_lock); 791 792 return 0; 793 } 794 795 static struct spi_driver spidev_spi_driver = { 796 .driver = { 797 .name = "spidev", 798 .of_match_table = of_match_ptr(spidev_dt_ids), 799 .acpi_match_table = ACPI_PTR(spidev_acpi_ids), 800 }, 801 .probe = spidev_probe, 802 .remove = spidev_remove, 803 804 /* NOTE: suspend/resume methods are not necessary here. 805 * We don't do anything except pass the requests to/from 806 * the underlying controller. The refrigerator handles 807 * most issues; the controller driver handles the rest. 808 */ 809 }; 810 811 /*-------------------------------------------------------------------------*/ 812 813 static int __init spidev_init(void) 814 { 815 int status; 816 817 /* Claim our 256 reserved device numbers. Then register a class 818 * that will key udev/mdev to add/remove /dev nodes. Last, register 819 * the driver which manages those device numbers. 820 */ 821 BUILD_BUG_ON(N_SPI_MINORS > 256); 822 status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops); 823 if (status < 0) 824 return status; 825 826 spidev_class = class_create(THIS_MODULE, "spidev"); 827 if (IS_ERR(spidev_class)) { 828 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name); 829 return PTR_ERR(spidev_class); 830 } 831 832 status = spi_register_driver(&spidev_spi_driver); 833 if (status < 0) { 834 class_destroy(spidev_class); 835 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name); 836 } 837 return status; 838 } 839 module_init(spidev_init); 840 841 static void __exit spidev_exit(void) 842 { 843 spi_unregister_driver(&spidev_spi_driver); 844 class_destroy(spidev_class); 845 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name); 846 } 847 module_exit(spidev_exit); 848 849 MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>"); 850 MODULE_DESCRIPTION("User mode SPI device interface"); 851 MODULE_LICENSE("GPL"); 852 MODULE_ALIAS("spi:spidev"); 853