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 struct spi_controller *ctlr = spi->controller; 400 u32 save = spi->mode; 401 402 if (tmp & ~SPI_MODE_MASK) { 403 retval = -EINVAL; 404 break; 405 } 406 407 if (ctlr->use_gpio_descriptors && ctlr->cs_gpiods && 408 ctlr->cs_gpiods[spi->chip_select]) 409 tmp |= SPI_CS_HIGH; 410 411 tmp |= spi->mode & ~SPI_MODE_MASK; 412 spi->mode = (u16)tmp; 413 retval = spi_setup(spi); 414 if (retval < 0) 415 spi->mode = save; 416 else 417 dev_dbg(&spi->dev, "spi mode %x\n", tmp); 418 } 419 break; 420 case SPI_IOC_WR_LSB_FIRST: 421 retval = get_user(tmp, (__u8 __user *)arg); 422 if (retval == 0) { 423 u32 save = spi->mode; 424 425 if (tmp) 426 spi->mode |= SPI_LSB_FIRST; 427 else 428 spi->mode &= ~SPI_LSB_FIRST; 429 retval = spi_setup(spi); 430 if (retval < 0) 431 spi->mode = save; 432 else 433 dev_dbg(&spi->dev, "%csb first\n", 434 tmp ? 'l' : 'm'); 435 } 436 break; 437 case SPI_IOC_WR_BITS_PER_WORD: 438 retval = get_user(tmp, (__u8 __user *)arg); 439 if (retval == 0) { 440 u8 save = spi->bits_per_word; 441 442 spi->bits_per_word = tmp; 443 retval = spi_setup(spi); 444 if (retval < 0) 445 spi->bits_per_word = save; 446 else 447 dev_dbg(&spi->dev, "%d bits per word\n", tmp); 448 } 449 break; 450 case SPI_IOC_WR_MAX_SPEED_HZ: 451 retval = get_user(tmp, (__u32 __user *)arg); 452 if (retval == 0) { 453 u32 save = spi->max_speed_hz; 454 455 spi->max_speed_hz = tmp; 456 retval = spi_setup(spi); 457 if (retval >= 0) 458 spidev->speed_hz = tmp; 459 else 460 dev_dbg(&spi->dev, "%d Hz (max)\n", tmp); 461 spi->max_speed_hz = save; 462 } 463 break; 464 465 default: 466 /* segmented and/or full-duplex I/O request */ 467 /* Check message and copy into scratch area */ 468 ioc = spidev_get_ioc_message(cmd, 469 (struct spi_ioc_transfer __user *)arg, &n_ioc); 470 if (IS_ERR(ioc)) { 471 retval = PTR_ERR(ioc); 472 break; 473 } 474 if (!ioc) 475 break; /* n_ioc is also 0 */ 476 477 /* translate to spi_message, execute */ 478 retval = spidev_message(spidev, ioc, n_ioc); 479 kfree(ioc); 480 break; 481 } 482 483 mutex_unlock(&spidev->buf_lock); 484 spi_dev_put(spi); 485 return retval; 486 } 487 488 #ifdef CONFIG_COMPAT 489 static long 490 spidev_compat_ioc_message(struct file *filp, unsigned int cmd, 491 unsigned long arg) 492 { 493 struct spi_ioc_transfer __user *u_ioc; 494 int retval = 0; 495 struct spidev_data *spidev; 496 struct spi_device *spi; 497 unsigned n_ioc, n; 498 struct spi_ioc_transfer *ioc; 499 500 u_ioc = (struct spi_ioc_transfer __user *) compat_ptr(arg); 501 502 /* guard against device removal before, or while, 503 * we issue this ioctl. 504 */ 505 spidev = filp->private_data; 506 spin_lock_irq(&spidev->spi_lock); 507 spi = spi_dev_get(spidev->spi); 508 spin_unlock_irq(&spidev->spi_lock); 509 510 if (spi == NULL) 511 return -ESHUTDOWN; 512 513 /* SPI_IOC_MESSAGE needs the buffer locked "normally" */ 514 mutex_lock(&spidev->buf_lock); 515 516 /* Check message and copy into scratch area */ 517 ioc = spidev_get_ioc_message(cmd, u_ioc, &n_ioc); 518 if (IS_ERR(ioc)) { 519 retval = PTR_ERR(ioc); 520 goto done; 521 } 522 if (!ioc) 523 goto done; /* n_ioc is also 0 */ 524 525 /* Convert buffer pointers */ 526 for (n = 0; n < n_ioc; n++) { 527 ioc[n].rx_buf = (uintptr_t) compat_ptr(ioc[n].rx_buf); 528 ioc[n].tx_buf = (uintptr_t) compat_ptr(ioc[n].tx_buf); 529 } 530 531 /* translate to spi_message, execute */ 532 retval = spidev_message(spidev, ioc, n_ioc); 533 kfree(ioc); 534 535 done: 536 mutex_unlock(&spidev->buf_lock); 537 spi_dev_put(spi); 538 return retval; 539 } 540 541 static long 542 spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) 543 { 544 if (_IOC_TYPE(cmd) == SPI_IOC_MAGIC 545 && _IOC_NR(cmd) == _IOC_NR(SPI_IOC_MESSAGE(0)) 546 && _IOC_DIR(cmd) == _IOC_WRITE) 547 return spidev_compat_ioc_message(filp, cmd, arg); 548 549 return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg)); 550 } 551 #else 552 #define spidev_compat_ioctl NULL 553 #endif /* CONFIG_COMPAT */ 554 555 static int spidev_open(struct inode *inode, struct file *filp) 556 { 557 struct spidev_data *spidev; 558 int status = -ENXIO; 559 560 mutex_lock(&device_list_lock); 561 562 list_for_each_entry(spidev, &device_list, device_entry) { 563 if (spidev->devt == inode->i_rdev) { 564 status = 0; 565 break; 566 } 567 } 568 569 if (status) { 570 pr_debug("spidev: nothing for minor %d\n", iminor(inode)); 571 goto err_find_dev; 572 } 573 574 if (!spidev->tx_buffer) { 575 spidev->tx_buffer = kmalloc(bufsiz, GFP_KERNEL); 576 if (!spidev->tx_buffer) { 577 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n"); 578 status = -ENOMEM; 579 goto err_find_dev; 580 } 581 } 582 583 if (!spidev->rx_buffer) { 584 spidev->rx_buffer = kmalloc(bufsiz, GFP_KERNEL); 585 if (!spidev->rx_buffer) { 586 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n"); 587 status = -ENOMEM; 588 goto err_alloc_rx_buf; 589 } 590 } 591 592 spidev->users++; 593 filp->private_data = spidev; 594 stream_open(inode, filp); 595 596 mutex_unlock(&device_list_lock); 597 return 0; 598 599 err_alloc_rx_buf: 600 kfree(spidev->tx_buffer); 601 spidev->tx_buffer = NULL; 602 err_find_dev: 603 mutex_unlock(&device_list_lock); 604 return status; 605 } 606 607 static int spidev_release(struct inode *inode, struct file *filp) 608 { 609 struct spidev_data *spidev; 610 611 mutex_lock(&device_list_lock); 612 spidev = filp->private_data; 613 filp->private_data = NULL; 614 615 /* last close? */ 616 spidev->users--; 617 if (!spidev->users) { 618 int dofree; 619 620 kfree(spidev->tx_buffer); 621 spidev->tx_buffer = NULL; 622 623 kfree(spidev->rx_buffer); 624 spidev->rx_buffer = NULL; 625 626 spin_lock_irq(&spidev->spi_lock); 627 if (spidev->spi) 628 spidev->speed_hz = spidev->spi->max_speed_hz; 629 630 /* ... after we unbound from the underlying device? */ 631 dofree = (spidev->spi == NULL); 632 spin_unlock_irq(&spidev->spi_lock); 633 634 if (dofree) 635 kfree(spidev); 636 } 637 #ifdef CONFIG_SPI_SLAVE 638 spi_slave_abort(spidev->spi); 639 #endif 640 mutex_unlock(&device_list_lock); 641 642 return 0; 643 } 644 645 static const struct file_operations spidev_fops = { 646 .owner = THIS_MODULE, 647 /* REVISIT switch to aio primitives, so that userspace 648 * gets more complete API coverage. It'll simplify things 649 * too, except for the locking. 650 */ 651 .write = spidev_write, 652 .read = spidev_read, 653 .unlocked_ioctl = spidev_ioctl, 654 .compat_ioctl = spidev_compat_ioctl, 655 .open = spidev_open, 656 .release = spidev_release, 657 .llseek = no_llseek, 658 }; 659 660 /*-------------------------------------------------------------------------*/ 661 662 /* The main reason to have this class is to make mdev/udev create the 663 * /dev/spidevB.C character device nodes exposing our userspace API. 664 * It also simplifies memory management. 665 */ 666 667 static struct class *spidev_class; 668 669 #ifdef CONFIG_OF 670 static const struct of_device_id spidev_dt_ids[] = { 671 { .compatible = "rohm,dh2228fv" }, 672 { .compatible = "lineartechnology,ltc2488" }, 673 { .compatible = "ge,achc" }, 674 { .compatible = "semtech,sx1301" }, 675 { .compatible = "lwn,bk4" }, 676 { .compatible = "dh,dhcom-board" }, 677 { .compatible = "menlo,m53cpld" }, 678 {}, 679 }; 680 MODULE_DEVICE_TABLE(of, spidev_dt_ids); 681 #endif 682 683 #ifdef CONFIG_ACPI 684 685 /* Dummy SPI devices not to be used in production systems */ 686 #define SPIDEV_ACPI_DUMMY 1 687 688 static const struct acpi_device_id spidev_acpi_ids[] = { 689 /* 690 * The ACPI SPT000* devices are only meant for development and 691 * testing. Systems used in production should have a proper ACPI 692 * description of the connected peripheral and they should also use 693 * a proper driver instead of poking directly to the SPI bus. 694 */ 695 { "SPT0001", SPIDEV_ACPI_DUMMY }, 696 { "SPT0002", SPIDEV_ACPI_DUMMY }, 697 { "SPT0003", SPIDEV_ACPI_DUMMY }, 698 {}, 699 }; 700 MODULE_DEVICE_TABLE(acpi, spidev_acpi_ids); 701 702 static void spidev_probe_acpi(struct spi_device *spi) 703 { 704 const struct acpi_device_id *id; 705 706 if (!has_acpi_companion(&spi->dev)) 707 return; 708 709 id = acpi_match_device(spidev_acpi_ids, &spi->dev); 710 if (WARN_ON(!id)) 711 return; 712 713 if (id->driver_data == SPIDEV_ACPI_DUMMY) 714 dev_warn(&spi->dev, "do not use this driver in production systems!\n"); 715 } 716 #else 717 static inline void spidev_probe_acpi(struct spi_device *spi) {} 718 #endif 719 720 /*-------------------------------------------------------------------------*/ 721 722 static int spidev_probe(struct spi_device *spi) 723 { 724 struct spidev_data *spidev; 725 int status; 726 unsigned long minor; 727 728 /* 729 * spidev should never be referenced in DT without a specific 730 * compatible string, it is a Linux implementation thing 731 * rather than a description of the hardware. 732 */ 733 WARN(spi->dev.of_node && 734 of_device_is_compatible(spi->dev.of_node, "spidev"), 735 "%pOF: buggy DT: spidev listed directly in DT\n", spi->dev.of_node); 736 737 spidev_probe_acpi(spi); 738 739 /* Allocate driver data */ 740 spidev = kzalloc(sizeof(*spidev), GFP_KERNEL); 741 if (!spidev) 742 return -ENOMEM; 743 744 /* Initialize the driver data */ 745 spidev->spi = spi; 746 spin_lock_init(&spidev->spi_lock); 747 mutex_init(&spidev->buf_lock); 748 749 INIT_LIST_HEAD(&spidev->device_entry); 750 751 /* If we can allocate a minor number, hook up this device. 752 * Reusing minors is fine so long as udev or mdev is working. 753 */ 754 mutex_lock(&device_list_lock); 755 minor = find_first_zero_bit(minors, N_SPI_MINORS); 756 if (minor < N_SPI_MINORS) { 757 struct device *dev; 758 759 spidev->devt = MKDEV(SPIDEV_MAJOR, minor); 760 dev = device_create(spidev_class, &spi->dev, spidev->devt, 761 spidev, "spidev%d.%d", 762 spi->master->bus_num, spi->chip_select); 763 status = PTR_ERR_OR_ZERO(dev); 764 } else { 765 dev_dbg(&spi->dev, "no minor number available!\n"); 766 status = -ENODEV; 767 } 768 if (status == 0) { 769 set_bit(minor, minors); 770 list_add(&spidev->device_entry, &device_list); 771 } 772 mutex_unlock(&device_list_lock); 773 774 spidev->speed_hz = spi->max_speed_hz; 775 776 if (status == 0) 777 spi_set_drvdata(spi, spidev); 778 else 779 kfree(spidev); 780 781 return status; 782 } 783 784 static int spidev_remove(struct spi_device *spi) 785 { 786 struct spidev_data *spidev = spi_get_drvdata(spi); 787 788 /* make sure ops on existing fds can abort cleanly */ 789 spin_lock_irq(&spidev->spi_lock); 790 spidev->spi = NULL; 791 spin_unlock_irq(&spidev->spi_lock); 792 793 /* prevent new opens */ 794 mutex_lock(&device_list_lock); 795 list_del(&spidev->device_entry); 796 device_destroy(spidev_class, spidev->devt); 797 clear_bit(MINOR(spidev->devt), minors); 798 if (spidev->users == 0) 799 kfree(spidev); 800 mutex_unlock(&device_list_lock); 801 802 return 0; 803 } 804 805 static struct spi_driver spidev_spi_driver = { 806 .driver = { 807 .name = "spidev", 808 .of_match_table = of_match_ptr(spidev_dt_ids), 809 .acpi_match_table = ACPI_PTR(spidev_acpi_ids), 810 }, 811 .probe = spidev_probe, 812 .remove = spidev_remove, 813 814 /* NOTE: suspend/resume methods are not necessary here. 815 * We don't do anything except pass the requests to/from 816 * the underlying controller. The refrigerator handles 817 * most issues; the controller driver handles the rest. 818 */ 819 }; 820 821 /*-------------------------------------------------------------------------*/ 822 823 static int __init spidev_init(void) 824 { 825 int status; 826 827 /* Claim our 256 reserved device numbers. Then register a class 828 * that will key udev/mdev to add/remove /dev nodes. Last, register 829 * the driver which manages those device numbers. 830 */ 831 BUILD_BUG_ON(N_SPI_MINORS > 256); 832 status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops); 833 if (status < 0) 834 return status; 835 836 spidev_class = class_create(THIS_MODULE, "spidev"); 837 if (IS_ERR(spidev_class)) { 838 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name); 839 return PTR_ERR(spidev_class); 840 } 841 842 status = spi_register_driver(&spidev_spi_driver); 843 if (status < 0) { 844 class_destroy(spidev_class); 845 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name); 846 } 847 return status; 848 } 849 module_init(spidev_init); 850 851 static void __exit spidev_exit(void) 852 { 853 spi_unregister_driver(&spidev_spi_driver); 854 class_destroy(spidev_class); 855 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name); 856 } 857 module_exit(spidev_exit); 858 859 MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>"); 860 MODULE_DESCRIPTION("User mode SPI device interface"); 861 MODULE_LICENSE("GPL"); 862 MODULE_ALIAS("spi:spidev"); 863