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.value = u_tmp->delay_usecs; 269 k_tmp->delay.unit = SPI_DELAY_UNIT_USECS; 270 k_tmp->speed_hz = u_tmp->speed_hz; 271 k_tmp->word_delay.value = u_tmp->word_delay_usecs; 272 k_tmp->word_delay.unit = SPI_DELAY_UNIT_USECS; 273 if (!k_tmp->speed_hz) 274 k_tmp->speed_hz = spidev->speed_hz; 275 #ifdef VERBOSE 276 dev_dbg(&spidev->spi->dev, 277 " xfer len %u %s%s%s%dbits %u usec %u usec %uHz\n", 278 u_tmp->len, 279 u_tmp->rx_buf ? "rx " : "", 280 u_tmp->tx_buf ? "tx " : "", 281 u_tmp->cs_change ? "cs " : "", 282 u_tmp->bits_per_word ? : spidev->spi->bits_per_word, 283 u_tmp->delay_usecs, 284 u_tmp->word_delay_usecs, 285 u_tmp->speed_hz ? : spidev->spi->max_speed_hz); 286 #endif 287 spi_message_add_tail(k_tmp, &msg); 288 } 289 290 status = spidev_sync(spidev, &msg); 291 if (status < 0) 292 goto done; 293 294 /* copy any rx data out of bounce buffer */ 295 rx_buf = spidev->rx_buffer; 296 for (n = n_xfers, u_tmp = u_xfers; n; n--, u_tmp++) { 297 if (u_tmp->rx_buf) { 298 if (copy_to_user((u8 __user *) 299 (uintptr_t) u_tmp->rx_buf, rx_buf, 300 u_tmp->len)) { 301 status = -EFAULT; 302 goto done; 303 } 304 rx_buf += u_tmp->len; 305 } 306 } 307 status = total; 308 309 done: 310 kfree(k_xfers); 311 return status; 312 } 313 314 static struct spi_ioc_transfer * 315 spidev_get_ioc_message(unsigned int cmd, struct spi_ioc_transfer __user *u_ioc, 316 unsigned *n_ioc) 317 { 318 u32 tmp; 319 320 /* Check type, command number and direction */ 321 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC 322 || _IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0)) 323 || _IOC_DIR(cmd) != _IOC_WRITE) 324 return ERR_PTR(-ENOTTY); 325 326 tmp = _IOC_SIZE(cmd); 327 if ((tmp % sizeof(struct spi_ioc_transfer)) != 0) 328 return ERR_PTR(-EINVAL); 329 *n_ioc = tmp / sizeof(struct spi_ioc_transfer); 330 if (*n_ioc == 0) 331 return NULL; 332 333 /* copy into scratch area */ 334 return memdup_user(u_ioc, tmp); 335 } 336 337 static long 338 spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) 339 { 340 int retval = 0; 341 struct spidev_data *spidev; 342 struct spi_device *spi; 343 u32 tmp; 344 unsigned n_ioc; 345 struct spi_ioc_transfer *ioc; 346 347 /* Check type and command number */ 348 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC) 349 return -ENOTTY; 350 351 /* guard against device removal before, or while, 352 * we issue this ioctl. 353 */ 354 spidev = filp->private_data; 355 spin_lock_irq(&spidev->spi_lock); 356 spi = spi_dev_get(spidev->spi); 357 spin_unlock_irq(&spidev->spi_lock); 358 359 if (spi == NULL) 360 return -ESHUTDOWN; 361 362 /* use the buffer lock here for triple duty: 363 * - prevent I/O (from us) so calling spi_setup() is safe; 364 * - prevent concurrent SPI_IOC_WR_* from morphing 365 * data fields while SPI_IOC_RD_* reads them; 366 * - SPI_IOC_MESSAGE needs the buffer locked "normally". 367 */ 368 mutex_lock(&spidev->buf_lock); 369 370 switch (cmd) { 371 /* read requests */ 372 case SPI_IOC_RD_MODE: 373 retval = put_user(spi->mode & SPI_MODE_MASK, 374 (__u8 __user *)arg); 375 break; 376 case SPI_IOC_RD_MODE32: 377 retval = put_user(spi->mode & SPI_MODE_MASK, 378 (__u32 __user *)arg); 379 break; 380 case SPI_IOC_RD_LSB_FIRST: 381 retval = put_user((spi->mode & SPI_LSB_FIRST) ? 1 : 0, 382 (__u8 __user *)arg); 383 break; 384 case SPI_IOC_RD_BITS_PER_WORD: 385 retval = put_user(spi->bits_per_word, (__u8 __user *)arg); 386 break; 387 case SPI_IOC_RD_MAX_SPEED_HZ: 388 retval = put_user(spidev->speed_hz, (__u32 __user *)arg); 389 break; 390 391 /* write requests */ 392 case SPI_IOC_WR_MODE: 393 case SPI_IOC_WR_MODE32: 394 if (cmd == SPI_IOC_WR_MODE) 395 retval = get_user(tmp, (u8 __user *)arg); 396 else 397 retval = get_user(tmp, (u32 __user *)arg); 398 if (retval == 0) { 399 u32 save = spi->mode; 400 401 if (tmp & ~SPI_MODE_MASK) { 402 retval = -EINVAL; 403 break; 404 } 405 406 tmp |= spi->mode & ~SPI_MODE_MASK; 407 spi->mode = (u16)tmp; 408 retval = spi_setup(spi); 409 if (retval < 0) 410 spi->mode = save; 411 else 412 dev_dbg(&spi->dev, "spi mode %x\n", tmp); 413 } 414 break; 415 case SPI_IOC_WR_LSB_FIRST: 416 retval = get_user(tmp, (__u8 __user *)arg); 417 if (retval == 0) { 418 u32 save = spi->mode; 419 420 if (tmp) 421 spi->mode |= SPI_LSB_FIRST; 422 else 423 spi->mode &= ~SPI_LSB_FIRST; 424 retval = spi_setup(spi); 425 if (retval < 0) 426 spi->mode = save; 427 else 428 dev_dbg(&spi->dev, "%csb first\n", 429 tmp ? 'l' : 'm'); 430 } 431 break; 432 case SPI_IOC_WR_BITS_PER_WORD: 433 retval = get_user(tmp, (__u8 __user *)arg); 434 if (retval == 0) { 435 u8 save = spi->bits_per_word; 436 437 spi->bits_per_word = tmp; 438 retval = spi_setup(spi); 439 if (retval < 0) 440 spi->bits_per_word = save; 441 else 442 dev_dbg(&spi->dev, "%d bits per word\n", tmp); 443 } 444 break; 445 case SPI_IOC_WR_MAX_SPEED_HZ: 446 retval = get_user(tmp, (__u32 __user *)arg); 447 if (retval == 0) { 448 u32 save = spi->max_speed_hz; 449 450 spi->max_speed_hz = tmp; 451 retval = spi_setup(spi); 452 if (retval >= 0) 453 spidev->speed_hz = tmp; 454 else 455 dev_dbg(&spi->dev, "%d Hz (max)\n", tmp); 456 spi->max_speed_hz = save; 457 } 458 break; 459 460 default: 461 /* segmented and/or full-duplex I/O request */ 462 /* Check message and copy into scratch area */ 463 ioc = spidev_get_ioc_message(cmd, 464 (struct spi_ioc_transfer __user *)arg, &n_ioc); 465 if (IS_ERR(ioc)) { 466 retval = PTR_ERR(ioc); 467 break; 468 } 469 if (!ioc) 470 break; /* n_ioc is also 0 */ 471 472 /* translate to spi_message, execute */ 473 retval = spidev_message(spidev, ioc, n_ioc); 474 kfree(ioc); 475 break; 476 } 477 478 mutex_unlock(&spidev->buf_lock); 479 spi_dev_put(spi); 480 return retval; 481 } 482 483 #ifdef CONFIG_COMPAT 484 static long 485 spidev_compat_ioc_message(struct file *filp, unsigned int cmd, 486 unsigned long arg) 487 { 488 struct spi_ioc_transfer __user *u_ioc; 489 int retval = 0; 490 struct spidev_data *spidev; 491 struct spi_device *spi; 492 unsigned n_ioc, n; 493 struct spi_ioc_transfer *ioc; 494 495 u_ioc = (struct spi_ioc_transfer __user *) compat_ptr(arg); 496 497 /* guard against device removal before, or while, 498 * we issue this ioctl. 499 */ 500 spidev = filp->private_data; 501 spin_lock_irq(&spidev->spi_lock); 502 spi = spi_dev_get(spidev->spi); 503 spin_unlock_irq(&spidev->spi_lock); 504 505 if (spi == NULL) 506 return -ESHUTDOWN; 507 508 /* SPI_IOC_MESSAGE needs the buffer locked "normally" */ 509 mutex_lock(&spidev->buf_lock); 510 511 /* Check message and copy into scratch area */ 512 ioc = spidev_get_ioc_message(cmd, u_ioc, &n_ioc); 513 if (IS_ERR(ioc)) { 514 retval = PTR_ERR(ioc); 515 goto done; 516 } 517 if (!ioc) 518 goto done; /* n_ioc is also 0 */ 519 520 /* Convert buffer pointers */ 521 for (n = 0; n < n_ioc; n++) { 522 ioc[n].rx_buf = (uintptr_t) compat_ptr(ioc[n].rx_buf); 523 ioc[n].tx_buf = (uintptr_t) compat_ptr(ioc[n].tx_buf); 524 } 525 526 /* translate to spi_message, execute */ 527 retval = spidev_message(spidev, ioc, n_ioc); 528 kfree(ioc); 529 530 done: 531 mutex_unlock(&spidev->buf_lock); 532 spi_dev_put(spi); 533 return retval; 534 } 535 536 static long 537 spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) 538 { 539 if (_IOC_TYPE(cmd) == SPI_IOC_MAGIC 540 && _IOC_NR(cmd) == _IOC_NR(SPI_IOC_MESSAGE(0)) 541 && _IOC_DIR(cmd) == _IOC_WRITE) 542 return spidev_compat_ioc_message(filp, cmd, arg); 543 544 return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg)); 545 } 546 #else 547 #define spidev_compat_ioctl NULL 548 #endif /* CONFIG_COMPAT */ 549 550 static int spidev_open(struct inode *inode, struct file *filp) 551 { 552 struct spidev_data *spidev; 553 int status = -ENXIO; 554 555 mutex_lock(&device_list_lock); 556 557 list_for_each_entry(spidev, &device_list, device_entry) { 558 if (spidev->devt == inode->i_rdev) { 559 status = 0; 560 break; 561 } 562 } 563 564 if (status) { 565 pr_debug("spidev: nothing for minor %d\n", iminor(inode)); 566 goto err_find_dev; 567 } 568 569 if (!spidev->tx_buffer) { 570 spidev->tx_buffer = kmalloc(bufsiz, GFP_KERNEL); 571 if (!spidev->tx_buffer) { 572 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n"); 573 status = -ENOMEM; 574 goto err_find_dev; 575 } 576 } 577 578 if (!spidev->rx_buffer) { 579 spidev->rx_buffer = kmalloc(bufsiz, GFP_KERNEL); 580 if (!spidev->rx_buffer) { 581 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n"); 582 status = -ENOMEM; 583 goto err_alloc_rx_buf; 584 } 585 } 586 587 spidev->users++; 588 filp->private_data = spidev; 589 stream_open(inode, filp); 590 591 mutex_unlock(&device_list_lock); 592 return 0; 593 594 err_alloc_rx_buf: 595 kfree(spidev->tx_buffer); 596 spidev->tx_buffer = NULL; 597 err_find_dev: 598 mutex_unlock(&device_list_lock); 599 return status; 600 } 601 602 static int spidev_release(struct inode *inode, struct file *filp) 603 { 604 struct spidev_data *spidev; 605 606 mutex_lock(&device_list_lock); 607 spidev = filp->private_data; 608 filp->private_data = NULL; 609 610 /* last close? */ 611 spidev->users--; 612 if (!spidev->users) { 613 int dofree; 614 615 kfree(spidev->tx_buffer); 616 spidev->tx_buffer = NULL; 617 618 kfree(spidev->rx_buffer); 619 spidev->rx_buffer = NULL; 620 621 spin_lock_irq(&spidev->spi_lock); 622 if (spidev->spi) 623 spidev->speed_hz = spidev->spi->max_speed_hz; 624 625 /* ... after we unbound from the underlying device? */ 626 dofree = (spidev->spi == NULL); 627 spin_unlock_irq(&spidev->spi_lock); 628 629 if (dofree) 630 kfree(spidev); 631 } 632 #ifdef CONFIG_SPI_SLAVE 633 spi_slave_abort(spidev->spi); 634 #endif 635 mutex_unlock(&device_list_lock); 636 637 return 0; 638 } 639 640 static const struct file_operations spidev_fops = { 641 .owner = THIS_MODULE, 642 /* REVISIT switch to aio primitives, so that userspace 643 * gets more complete API coverage. It'll simplify things 644 * too, except for the locking. 645 */ 646 .write = spidev_write, 647 .read = spidev_read, 648 .unlocked_ioctl = spidev_ioctl, 649 .compat_ioctl = spidev_compat_ioctl, 650 .open = spidev_open, 651 .release = spidev_release, 652 .llseek = no_llseek, 653 }; 654 655 /*-------------------------------------------------------------------------*/ 656 657 /* The main reason to have this class is to make mdev/udev create the 658 * /dev/spidevB.C character device nodes exposing our userspace API. 659 * It also simplifies memory management. 660 */ 661 662 static struct class *spidev_class; 663 664 #ifdef CONFIG_OF 665 static const struct of_device_id spidev_dt_ids[] = { 666 { .compatible = "rohm,dh2228fv" }, 667 { .compatible = "lineartechnology,ltc2488" }, 668 { .compatible = "ge,achc" }, 669 { .compatible = "semtech,sx1301" }, 670 { .compatible = "lwn,bk4" }, 671 { .compatible = "dh,dhcom-board" }, 672 { .compatible = "menlo,m53cpld" }, 673 {}, 674 }; 675 MODULE_DEVICE_TABLE(of, spidev_dt_ids); 676 #endif 677 678 #ifdef CONFIG_ACPI 679 680 /* Dummy SPI devices not to be used in production systems */ 681 #define SPIDEV_ACPI_DUMMY 1 682 683 static const struct acpi_device_id spidev_acpi_ids[] = { 684 /* 685 * The ACPI SPT000* devices are only meant for development and 686 * testing. Systems used in production should have a proper ACPI 687 * description of the connected peripheral and they should also use 688 * a proper driver instead of poking directly to the SPI bus. 689 */ 690 { "SPT0001", SPIDEV_ACPI_DUMMY }, 691 { "SPT0002", SPIDEV_ACPI_DUMMY }, 692 { "SPT0003", SPIDEV_ACPI_DUMMY }, 693 {}, 694 }; 695 MODULE_DEVICE_TABLE(acpi, spidev_acpi_ids); 696 697 static void spidev_probe_acpi(struct spi_device *spi) 698 { 699 const struct acpi_device_id *id; 700 701 if (!has_acpi_companion(&spi->dev)) 702 return; 703 704 id = acpi_match_device(spidev_acpi_ids, &spi->dev); 705 if (WARN_ON(!id)) 706 return; 707 708 if (id->driver_data == SPIDEV_ACPI_DUMMY) 709 dev_warn(&spi->dev, "do not use this driver in production systems!\n"); 710 } 711 #else 712 static inline void spidev_probe_acpi(struct spi_device *spi) {} 713 #endif 714 715 /*-------------------------------------------------------------------------*/ 716 717 static int spidev_probe(struct spi_device *spi) 718 { 719 struct spidev_data *spidev; 720 int status; 721 unsigned long minor; 722 723 /* 724 * spidev should never be referenced in DT without a specific 725 * compatible string, it is a Linux implementation thing 726 * rather than a description of the hardware. 727 */ 728 WARN(spi->dev.of_node && 729 of_device_is_compatible(spi->dev.of_node, "spidev"), 730 "%pOF: buggy DT: spidev listed directly in DT\n", spi->dev.of_node); 731 732 spidev_probe_acpi(spi); 733 734 /* Allocate driver data */ 735 spidev = kzalloc(sizeof(*spidev), GFP_KERNEL); 736 if (!spidev) 737 return -ENOMEM; 738 739 /* Initialize the driver data */ 740 spidev->spi = spi; 741 spin_lock_init(&spidev->spi_lock); 742 mutex_init(&spidev->buf_lock); 743 744 INIT_LIST_HEAD(&spidev->device_entry); 745 746 /* If we can allocate a minor number, hook up this device. 747 * Reusing minors is fine so long as udev or mdev is working. 748 */ 749 mutex_lock(&device_list_lock); 750 minor = find_first_zero_bit(minors, N_SPI_MINORS); 751 if (minor < N_SPI_MINORS) { 752 struct device *dev; 753 754 spidev->devt = MKDEV(SPIDEV_MAJOR, minor); 755 dev = device_create(spidev_class, &spi->dev, spidev->devt, 756 spidev, "spidev%d.%d", 757 spi->master->bus_num, spi->chip_select); 758 status = PTR_ERR_OR_ZERO(dev); 759 } else { 760 dev_dbg(&spi->dev, "no minor number available!\n"); 761 status = -ENODEV; 762 } 763 if (status == 0) { 764 set_bit(minor, minors); 765 list_add(&spidev->device_entry, &device_list); 766 } 767 mutex_unlock(&device_list_lock); 768 769 spidev->speed_hz = spi->max_speed_hz; 770 771 if (status == 0) 772 spi_set_drvdata(spi, spidev); 773 else 774 kfree(spidev); 775 776 return status; 777 } 778 779 static int spidev_remove(struct spi_device *spi) 780 { 781 struct spidev_data *spidev = spi_get_drvdata(spi); 782 783 /* make sure ops on existing fds can abort cleanly */ 784 spin_lock_irq(&spidev->spi_lock); 785 spidev->spi = NULL; 786 spin_unlock_irq(&spidev->spi_lock); 787 788 /* prevent new opens */ 789 mutex_lock(&device_list_lock); 790 list_del(&spidev->device_entry); 791 device_destroy(spidev_class, spidev->devt); 792 clear_bit(MINOR(spidev->devt), minors); 793 if (spidev->users == 0) 794 kfree(spidev); 795 mutex_unlock(&device_list_lock); 796 797 return 0; 798 } 799 800 static struct spi_driver spidev_spi_driver = { 801 .driver = { 802 .name = "spidev", 803 .of_match_table = of_match_ptr(spidev_dt_ids), 804 .acpi_match_table = ACPI_PTR(spidev_acpi_ids), 805 }, 806 .probe = spidev_probe, 807 .remove = spidev_remove, 808 809 /* NOTE: suspend/resume methods are not necessary here. 810 * We don't do anything except pass the requests to/from 811 * the underlying controller. The refrigerator handles 812 * most issues; the controller driver handles the rest. 813 */ 814 }; 815 816 /*-------------------------------------------------------------------------*/ 817 818 static int __init spidev_init(void) 819 { 820 int status; 821 822 /* Claim our 256 reserved device numbers. Then register a class 823 * that will key udev/mdev to add/remove /dev nodes. Last, register 824 * the driver which manages those device numbers. 825 */ 826 BUILD_BUG_ON(N_SPI_MINORS > 256); 827 status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops); 828 if (status < 0) 829 return status; 830 831 spidev_class = class_create(THIS_MODULE, "spidev"); 832 if (IS_ERR(spidev_class)) { 833 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name); 834 return PTR_ERR(spidev_class); 835 } 836 837 status = spi_register_driver(&spidev_spi_driver); 838 if (status < 0) { 839 class_destroy(spidev_class); 840 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name); 841 } 842 return status; 843 } 844 module_init(spidev_init); 845 846 static void __exit spidev_exit(void) 847 { 848 spi_unregister_driver(&spidev_spi_driver); 849 class_destroy(spidev_class); 850 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name); 851 } 852 module_exit(spidev_exit); 853 854 MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>"); 855 MODULE_DESCRIPTION("User mode SPI device interface"); 856 MODULE_LICENSE("GPL"); 857 MODULE_ALIAS("spi:spidev"); 858