1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Simple synchronous userspace interface to SPI devices 4 * 5 * Copyright (C) 2006 SWAPP 6 * Andrea Paterniani <a.paterniani@swapp-eng.it> 7 * Copyright (C) 2007 David Brownell (simplification, cleanup) 8 */ 9 10 #include <linux/init.h> 11 #include <linux/ioctl.h> 12 #include <linux/fs.h> 13 #include <linux/device.h> 14 #include <linux/err.h> 15 #include <linux/list.h> 16 #include <linux/errno.h> 17 #include <linux/mod_devicetable.h> 18 #include <linux/module.h> 19 #include <linux/mutex.h> 20 #include <linux/property.h> 21 #include <linux/slab.h> 22 #include <linux/compat.h> 23 24 #include <linux/spi/spi.h> 25 #include <linux/spi/spidev.h> 26 27 #include <linux/uaccess.h> 28 29 30 /* 31 * This supports access to SPI devices using normal userspace I/O calls. 32 * Note that while traditional UNIX/POSIX I/O semantics are half duplex, 33 * and often mask message boundaries, full SPI support requires full duplex 34 * transfers. There are several kinds of internal message boundaries to 35 * handle chipselect management and other protocol options. 36 * 37 * SPI has a character major number assigned. We allocate minor numbers 38 * dynamically using a bitmask. You must use hotplug tools, such as udev 39 * (or mdev with busybox) to create and destroy the /dev/spidevB.C device 40 * nodes, since there is no fixed association of minor numbers with any 41 * particular SPI bus or device. 42 */ 43 #define SPIDEV_MAJOR 153 /* assigned */ 44 #define N_SPI_MINORS 32 /* ... up to 256 */ 45 46 static DECLARE_BITMAP(minors, N_SPI_MINORS); 47 48 static_assert(N_SPI_MINORS > 0 && N_SPI_MINORS <= 256); 49 50 /* Bit masks for spi_device.mode management. Note that incorrect 51 * settings for some settings can cause *lots* of trouble for other 52 * devices on a shared bus: 53 * 54 * - CS_HIGH ... this device will be active when it shouldn't be 55 * - 3WIRE ... when active, it won't behave as it should 56 * - NO_CS ... there will be no explicit message boundaries; this 57 * is completely incompatible with the shared bus model 58 * - READY ... transfers may proceed when they shouldn't. 59 * 60 * REVISIT should changing those flags be privileged? 61 */ 62 #define SPI_MODE_MASK (SPI_MODE_X_MASK | SPI_CS_HIGH \ 63 | SPI_LSB_FIRST | SPI_3WIRE | SPI_LOOP \ 64 | SPI_NO_CS | SPI_READY | SPI_TX_DUAL \ 65 | SPI_TX_QUAD | SPI_TX_OCTAL | SPI_RX_DUAL \ 66 | SPI_RX_QUAD | SPI_RX_OCTAL \ 67 | SPI_RX_CPHA_FLIP | SPI_3WIRE_HIZ \ 68 | SPI_MOSI_IDLE_LOW) 69 70 struct spidev_data { 71 dev_t devt; 72 struct mutex spi_lock; 73 struct spi_device *spi; 74 struct list_head device_entry; 75 76 /* TX/RX buffers are NULL unless this device is open (users > 0) */ 77 struct mutex buf_lock; 78 unsigned users; 79 u8 *tx_buffer; 80 u8 *rx_buffer; 81 u32 speed_hz; 82 }; 83 84 static LIST_HEAD(device_list); 85 static DEFINE_MUTEX(device_list_lock); 86 87 static unsigned bufsiz = 4096; 88 module_param(bufsiz, uint, S_IRUGO); 89 MODULE_PARM_DESC(bufsiz, "data bytes in biggest supported SPI message"); 90 91 /*-------------------------------------------------------------------------*/ 92 93 static ssize_t spidev_sync_unlocked(struct spi_device * spi,struct spi_message * message)94 spidev_sync_unlocked(struct spi_device *spi, struct spi_message *message) 95 { 96 ssize_t status; 97 98 status = spi_sync(spi, message); 99 if (status == 0) 100 status = message->actual_length; 101 102 return status; 103 } 104 105 static ssize_t spidev_sync(struct spidev_data * spidev,struct spi_message * message)106 spidev_sync(struct spidev_data *spidev, struct spi_message *message) 107 { 108 ssize_t status; 109 struct spi_device *spi; 110 111 mutex_lock(&spidev->spi_lock); 112 spi = spidev->spi; 113 114 if (spi == NULL) 115 status = -ESHUTDOWN; 116 else 117 status = spidev_sync_unlocked(spi, message); 118 119 mutex_unlock(&spidev->spi_lock); 120 return status; 121 } 122 123 static inline ssize_t spidev_sync_write(struct spidev_data * spidev,size_t len)124 spidev_sync_write(struct spidev_data *spidev, size_t len) 125 { 126 struct spi_transfer t = { 127 .tx_buf = spidev->tx_buffer, 128 .len = len, 129 .speed_hz = spidev->speed_hz, 130 }; 131 struct spi_message m; 132 133 spi_message_init(&m); 134 spi_message_add_tail(&t, &m); 135 return spidev_sync(spidev, &m); 136 } 137 138 static inline ssize_t spidev_sync_read(struct spidev_data * spidev,size_t len)139 spidev_sync_read(struct spidev_data *spidev, size_t len) 140 { 141 struct spi_transfer t = { 142 .rx_buf = spidev->rx_buffer, 143 .len = len, 144 .speed_hz = spidev->speed_hz, 145 }; 146 struct spi_message m; 147 148 spi_message_init(&m); 149 spi_message_add_tail(&t, &m); 150 return spidev_sync(spidev, &m); 151 } 152 153 /*-------------------------------------------------------------------------*/ 154 155 /* Read-only message with current device setup */ 156 static ssize_t spidev_read(struct file * filp,char __user * buf,size_t count,loff_t * f_pos)157 spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos) 158 { 159 struct spidev_data *spidev; 160 ssize_t status; 161 162 /* chipselect only toggles at start or end of operation */ 163 if (count > bufsiz) 164 return -EMSGSIZE; 165 166 spidev = filp->private_data; 167 168 mutex_lock(&spidev->buf_lock); 169 status = spidev_sync_read(spidev, count); 170 if (status > 0) { 171 unsigned long missing; 172 173 missing = copy_to_user(buf, spidev->rx_buffer, status); 174 if (missing == status) 175 status = -EFAULT; 176 else 177 status = status - missing; 178 } 179 mutex_unlock(&spidev->buf_lock); 180 181 return status; 182 } 183 184 /* Write-only message with current device setup */ 185 static ssize_t spidev_write(struct file * filp,const char __user * buf,size_t count,loff_t * f_pos)186 spidev_write(struct file *filp, const char __user *buf, 187 size_t count, loff_t *f_pos) 188 { 189 struct spidev_data *spidev; 190 ssize_t status; 191 unsigned long missing; 192 193 /* chipselect only toggles at start or end of operation */ 194 if (count > bufsiz) 195 return -EMSGSIZE; 196 197 spidev = filp->private_data; 198 199 mutex_lock(&spidev->buf_lock); 200 missing = copy_from_user(spidev->tx_buffer, buf, count); 201 if (missing == 0) 202 status = spidev_sync_write(spidev, count); 203 else 204 status = -EFAULT; 205 mutex_unlock(&spidev->buf_lock); 206 207 return status; 208 } 209 spidev_message(struct spidev_data * spidev,struct spi_ioc_transfer * u_xfers,unsigned n_xfers)210 static int spidev_message(struct spidev_data *spidev, 211 struct spi_ioc_transfer *u_xfers, unsigned n_xfers) 212 { 213 struct spi_message msg; 214 struct spi_transfer *k_xfers; 215 struct spi_transfer *k_tmp; 216 struct spi_ioc_transfer *u_tmp; 217 unsigned n, total, tx_total, rx_total; 218 u8 *tx_buf, *rx_buf; 219 int status = -EFAULT; 220 221 spi_message_init(&msg); 222 k_xfers = kcalloc(n_xfers, sizeof(*k_tmp), GFP_KERNEL); 223 if (k_xfers == NULL) 224 return -ENOMEM; 225 226 /* Construct spi_message, copying any tx data to bounce buffer. 227 * We walk the array of user-provided transfers, using each one 228 * to initialize a kernel version of the same transfer. 229 */ 230 tx_buf = spidev->tx_buffer; 231 rx_buf = spidev->rx_buffer; 232 total = 0; 233 tx_total = 0; 234 rx_total = 0; 235 for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers; 236 n; 237 n--, k_tmp++, u_tmp++) { 238 /* Ensure that also following allocations from rx_buf/tx_buf will meet 239 * DMA alignment requirements. 240 */ 241 unsigned int len_aligned = ALIGN(u_tmp->len, ARCH_DMA_MINALIGN); 242 243 k_tmp->len = u_tmp->len; 244 245 total += k_tmp->len; 246 /* Since the function returns the total length of transfers 247 * on success, restrict the total to positive int values to 248 * avoid the return value looking like an error. Also check 249 * each transfer length to avoid arithmetic overflow. 250 */ 251 if (total > INT_MAX || k_tmp->len > INT_MAX) { 252 status = -EMSGSIZE; 253 goto done; 254 } 255 256 if (u_tmp->rx_buf) { 257 /* this transfer needs space in RX bounce buffer */ 258 rx_total += len_aligned; 259 if (rx_total > bufsiz) { 260 status = -EMSGSIZE; 261 goto done; 262 } 263 k_tmp->rx_buf = rx_buf; 264 rx_buf += len_aligned; 265 } 266 if (u_tmp->tx_buf) { 267 /* this transfer needs space in TX bounce buffer */ 268 tx_total += len_aligned; 269 if (tx_total > bufsiz) { 270 status = -EMSGSIZE; 271 goto done; 272 } 273 k_tmp->tx_buf = tx_buf; 274 if (copy_from_user(tx_buf, (const u8 __user *) 275 (uintptr_t) u_tmp->tx_buf, 276 u_tmp->len)) 277 goto done; 278 tx_buf += len_aligned; 279 } 280 281 k_tmp->cs_change = !!u_tmp->cs_change; 282 k_tmp->tx_nbits = u_tmp->tx_nbits; 283 k_tmp->rx_nbits = u_tmp->rx_nbits; 284 k_tmp->bits_per_word = u_tmp->bits_per_word; 285 k_tmp->delay.value = u_tmp->delay_usecs; 286 k_tmp->delay.unit = SPI_DELAY_UNIT_USECS; 287 k_tmp->speed_hz = u_tmp->speed_hz; 288 k_tmp->word_delay.value = u_tmp->word_delay_usecs; 289 k_tmp->word_delay.unit = SPI_DELAY_UNIT_USECS; 290 if (!k_tmp->speed_hz) 291 k_tmp->speed_hz = spidev->speed_hz; 292 #ifdef VERBOSE 293 dev_dbg(&spidev->spi->dev, 294 " xfer len %u %s%s%s%dbits %u usec %u usec %uHz\n", 295 k_tmp->len, 296 k_tmp->rx_buf ? "rx " : "", 297 k_tmp->tx_buf ? "tx " : "", 298 k_tmp->cs_change ? "cs " : "", 299 k_tmp->bits_per_word ? : spidev->spi->bits_per_word, 300 k_tmp->delay.value, 301 k_tmp->word_delay.value, 302 k_tmp->speed_hz ? : spidev->spi->max_speed_hz); 303 #endif 304 spi_message_add_tail(k_tmp, &msg); 305 } 306 307 status = spidev_sync_unlocked(spidev->spi, &msg); 308 if (status < 0) 309 goto done; 310 311 /* copy any rx data out of bounce buffer */ 312 for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers; 313 n; 314 n--, k_tmp++, u_tmp++) { 315 if (u_tmp->rx_buf) { 316 if (copy_to_user((u8 __user *) 317 (uintptr_t) u_tmp->rx_buf, k_tmp->rx_buf, 318 u_tmp->len)) { 319 status = -EFAULT; 320 goto done; 321 } 322 } 323 } 324 status = total; 325 326 done: 327 kfree(k_xfers); 328 return status; 329 } 330 331 static struct spi_ioc_transfer * spidev_get_ioc_message(unsigned int cmd,struct spi_ioc_transfer __user * u_ioc,unsigned * n_ioc)332 spidev_get_ioc_message(unsigned int cmd, struct spi_ioc_transfer __user *u_ioc, 333 unsigned *n_ioc) 334 { 335 u32 tmp; 336 337 /* Check type, command number and direction */ 338 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC 339 || _IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0)) 340 || _IOC_DIR(cmd) != _IOC_WRITE) 341 return ERR_PTR(-ENOTTY); 342 343 tmp = _IOC_SIZE(cmd); 344 if ((tmp % sizeof(struct spi_ioc_transfer)) != 0) 345 return ERR_PTR(-EINVAL); 346 *n_ioc = tmp / sizeof(struct spi_ioc_transfer); 347 if (*n_ioc == 0) 348 return NULL; 349 350 /* copy into scratch area */ 351 return memdup_user(u_ioc, tmp); 352 } 353 354 static long spidev_ioctl(struct file * filp,unsigned int cmd,unsigned long arg)355 spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) 356 { 357 int retval = 0; 358 struct spidev_data *spidev; 359 struct spi_device *spi; 360 u32 tmp; 361 unsigned n_ioc; 362 struct spi_ioc_transfer *ioc; 363 364 /* Check type and command number */ 365 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC) 366 return -ENOTTY; 367 368 /* guard against device removal before, or while, 369 * we issue this ioctl. 370 */ 371 spidev = filp->private_data; 372 mutex_lock(&spidev->spi_lock); 373 spi = spi_dev_get(spidev->spi); 374 if (spi == NULL) { 375 mutex_unlock(&spidev->spi_lock); 376 return -ESHUTDOWN; 377 } 378 379 /* use the buffer lock here for triple duty: 380 * - prevent I/O (from us) so calling spi_setup() is safe; 381 * - prevent concurrent SPI_IOC_WR_* from morphing 382 * data fields while SPI_IOC_RD_* reads them; 383 * - SPI_IOC_MESSAGE needs the buffer locked "normally". 384 */ 385 mutex_lock(&spidev->buf_lock); 386 387 switch (cmd) { 388 /* read requests */ 389 case SPI_IOC_RD_MODE: 390 case SPI_IOC_RD_MODE32: 391 tmp = spi->mode; 392 393 { 394 struct spi_controller *ctlr = spi->controller; 395 396 if (ctlr->use_gpio_descriptors && ctlr->cs_gpiods && 397 ctlr->cs_gpiods[spi_get_chipselect(spi, 0)]) 398 tmp &= ~SPI_CS_HIGH; 399 } 400 401 if (cmd == SPI_IOC_RD_MODE) 402 retval = put_user(tmp & SPI_MODE_MASK, 403 (__u8 __user *)arg); 404 else 405 retval = put_user(tmp & SPI_MODE_MASK, 406 (__u32 __user *)arg); 407 break; 408 case SPI_IOC_RD_LSB_FIRST: 409 retval = put_user((spi->mode & SPI_LSB_FIRST) ? 1 : 0, 410 (__u8 __user *)arg); 411 break; 412 case SPI_IOC_RD_BITS_PER_WORD: 413 retval = put_user(spi->bits_per_word, (__u8 __user *)arg); 414 break; 415 case SPI_IOC_RD_MAX_SPEED_HZ: 416 retval = put_user(spidev->speed_hz, (__u32 __user *)arg); 417 break; 418 419 /* write requests */ 420 case SPI_IOC_WR_MODE: 421 case SPI_IOC_WR_MODE32: 422 if (cmd == SPI_IOC_WR_MODE) 423 retval = get_user(tmp, (u8 __user *)arg); 424 else 425 retval = get_user(tmp, (u32 __user *)arg); 426 if (retval == 0) { 427 struct spi_controller *ctlr = spi->controller; 428 u32 save = spi->mode; 429 430 if (tmp & ~SPI_MODE_MASK) { 431 retval = -EINVAL; 432 break; 433 } 434 435 if (ctlr->use_gpio_descriptors && ctlr->cs_gpiods && 436 ctlr->cs_gpiods[spi_get_chipselect(spi, 0)]) 437 tmp |= SPI_CS_HIGH; 438 439 tmp |= spi->mode & ~SPI_MODE_MASK; 440 spi->mode = tmp & SPI_MODE_USER_MASK; 441 retval = spi_setup(spi); 442 if (retval < 0) 443 spi->mode = save; 444 else 445 dev_dbg(&spi->dev, "spi mode %x\n", tmp); 446 } 447 break; 448 case SPI_IOC_WR_LSB_FIRST: 449 retval = get_user(tmp, (__u8 __user *)arg); 450 if (retval == 0) { 451 u32 save = spi->mode; 452 453 if (tmp) 454 spi->mode |= SPI_LSB_FIRST; 455 else 456 spi->mode &= ~SPI_LSB_FIRST; 457 retval = spi_setup(spi); 458 if (retval < 0) 459 spi->mode = save; 460 else 461 dev_dbg(&spi->dev, "%csb first\n", 462 tmp ? 'l' : 'm'); 463 } 464 break; 465 case SPI_IOC_WR_BITS_PER_WORD: 466 retval = get_user(tmp, (__u8 __user *)arg); 467 if (retval == 0) { 468 u8 save = spi->bits_per_word; 469 470 spi->bits_per_word = tmp; 471 retval = spi_setup(spi); 472 if (retval < 0) 473 spi->bits_per_word = save; 474 else 475 dev_dbg(&spi->dev, "%d bits per word\n", tmp); 476 } 477 break; 478 case SPI_IOC_WR_MAX_SPEED_HZ: { 479 u32 save; 480 481 retval = get_user(tmp, (__u32 __user *)arg); 482 if (retval) 483 break; 484 if (tmp == 0) { 485 retval = -EINVAL; 486 break; 487 } 488 489 save = spi->max_speed_hz; 490 491 spi->max_speed_hz = tmp; 492 retval = spi_setup(spi); 493 if (retval == 0) { 494 spidev->speed_hz = tmp; 495 dev_dbg(&spi->dev, "%d Hz (max)\n", spidev->speed_hz); 496 } 497 498 spi->max_speed_hz = save; 499 break; 500 } 501 default: 502 /* segmented and/or full-duplex I/O request */ 503 /* Check message and copy into scratch area */ 504 ioc = spidev_get_ioc_message(cmd, 505 (struct spi_ioc_transfer __user *)arg, &n_ioc); 506 if (IS_ERR(ioc)) { 507 retval = PTR_ERR(ioc); 508 break; 509 } 510 if (!ioc) 511 break; /* n_ioc is also 0 */ 512 513 /* translate to spi_message, execute */ 514 retval = spidev_message(spidev, ioc, n_ioc); 515 kfree(ioc); 516 break; 517 } 518 519 mutex_unlock(&spidev->buf_lock); 520 spi_dev_put(spi); 521 mutex_unlock(&spidev->spi_lock); 522 return retval; 523 } 524 525 #ifdef CONFIG_COMPAT 526 static long spidev_compat_ioc_message(struct file * filp,unsigned int cmd,unsigned long arg)527 spidev_compat_ioc_message(struct file *filp, unsigned int cmd, 528 unsigned long arg) 529 { 530 struct spi_ioc_transfer __user *u_ioc; 531 int retval = 0; 532 struct spidev_data *spidev; 533 struct spi_device *spi; 534 unsigned n_ioc, n; 535 struct spi_ioc_transfer *ioc; 536 537 u_ioc = (struct spi_ioc_transfer __user *) compat_ptr(arg); 538 539 /* guard against device removal before, or while, 540 * we issue this ioctl. 541 */ 542 spidev = filp->private_data; 543 mutex_lock(&spidev->spi_lock); 544 spi = spi_dev_get(spidev->spi); 545 if (spi == NULL) { 546 mutex_unlock(&spidev->spi_lock); 547 return -ESHUTDOWN; 548 } 549 550 /* SPI_IOC_MESSAGE needs the buffer locked "normally" */ 551 mutex_lock(&spidev->buf_lock); 552 553 /* Check message and copy into scratch area */ 554 ioc = spidev_get_ioc_message(cmd, u_ioc, &n_ioc); 555 if (IS_ERR(ioc)) { 556 retval = PTR_ERR(ioc); 557 goto done; 558 } 559 if (!ioc) 560 goto done; /* n_ioc is also 0 */ 561 562 /* Convert buffer pointers */ 563 for (n = 0; n < n_ioc; n++) { 564 ioc[n].rx_buf = (uintptr_t) compat_ptr(ioc[n].rx_buf); 565 ioc[n].tx_buf = (uintptr_t) compat_ptr(ioc[n].tx_buf); 566 } 567 568 /* translate to spi_message, execute */ 569 retval = spidev_message(spidev, ioc, n_ioc); 570 kfree(ioc); 571 572 done: 573 mutex_unlock(&spidev->buf_lock); 574 spi_dev_put(spi); 575 mutex_unlock(&spidev->spi_lock); 576 return retval; 577 } 578 579 static long spidev_compat_ioctl(struct file * filp,unsigned int cmd,unsigned long arg)580 spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) 581 { 582 if (_IOC_TYPE(cmd) == SPI_IOC_MAGIC 583 && _IOC_NR(cmd) == _IOC_NR(SPI_IOC_MESSAGE(0)) 584 && _IOC_DIR(cmd) == _IOC_WRITE) 585 return spidev_compat_ioc_message(filp, cmd, arg); 586 587 return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg)); 588 } 589 #else 590 #define spidev_compat_ioctl NULL 591 #endif /* CONFIG_COMPAT */ 592 spidev_open(struct inode * inode,struct file * filp)593 static int spidev_open(struct inode *inode, struct file *filp) 594 { 595 struct spidev_data *spidev = NULL, *iter; 596 int status = -ENXIO; 597 598 mutex_lock(&device_list_lock); 599 600 list_for_each_entry(iter, &device_list, device_entry) { 601 if (iter->devt == inode->i_rdev) { 602 status = 0; 603 spidev = iter; 604 break; 605 } 606 } 607 608 if (!spidev) { 609 pr_debug("spidev: nothing for minor %d\n", iminor(inode)); 610 goto err_find_dev; 611 } 612 613 if (!spidev->tx_buffer) { 614 spidev->tx_buffer = kmalloc(bufsiz, GFP_KERNEL); 615 if (!spidev->tx_buffer) { 616 status = -ENOMEM; 617 goto err_find_dev; 618 } 619 } 620 621 if (!spidev->rx_buffer) { 622 spidev->rx_buffer = kmalloc(bufsiz, GFP_KERNEL); 623 if (!spidev->rx_buffer) { 624 status = -ENOMEM; 625 goto err_alloc_rx_buf; 626 } 627 } 628 629 spidev->users++; 630 filp->private_data = spidev; 631 stream_open(inode, filp); 632 633 mutex_unlock(&device_list_lock); 634 return 0; 635 636 err_alloc_rx_buf: 637 kfree(spidev->tx_buffer); 638 spidev->tx_buffer = NULL; 639 err_find_dev: 640 mutex_unlock(&device_list_lock); 641 return status; 642 } 643 spidev_release(struct inode * inode,struct file * filp)644 static int spidev_release(struct inode *inode, struct file *filp) 645 { 646 struct spidev_data *spidev; 647 int dofree; 648 649 mutex_lock(&device_list_lock); 650 spidev = filp->private_data; 651 filp->private_data = NULL; 652 653 mutex_lock(&spidev->spi_lock); 654 /* ... after we unbound from the underlying device? */ 655 dofree = (spidev->spi == NULL); 656 mutex_unlock(&spidev->spi_lock); 657 658 /* last close? */ 659 spidev->users--; 660 if (!spidev->users) { 661 662 kfree(spidev->tx_buffer); 663 spidev->tx_buffer = NULL; 664 665 kfree(spidev->rx_buffer); 666 spidev->rx_buffer = NULL; 667 668 if (dofree) 669 kfree(spidev); 670 else 671 spidev->speed_hz = spidev->spi->max_speed_hz; 672 } 673 #ifdef CONFIG_SPI_SLAVE 674 if (!dofree) 675 spi_slave_abort(spidev->spi); 676 #endif 677 mutex_unlock(&device_list_lock); 678 679 return 0; 680 } 681 682 static const struct file_operations spidev_fops = { 683 .owner = THIS_MODULE, 684 /* REVISIT switch to aio primitives, so that userspace 685 * gets more complete API coverage. It'll simplify things 686 * too, except for the locking. 687 */ 688 .write = spidev_write, 689 .read = spidev_read, 690 .unlocked_ioctl = spidev_ioctl, 691 .compat_ioctl = spidev_compat_ioctl, 692 .open = spidev_open, 693 .release = spidev_release, 694 .llseek = no_llseek, 695 }; 696 697 /*-------------------------------------------------------------------------*/ 698 699 /* The main reason to have this class is to make mdev/udev create the 700 * /dev/spidevB.C character device nodes exposing our userspace API. 701 * It also simplifies memory management. 702 */ 703 704 static struct class *spidev_class; 705 706 static const struct spi_device_id spidev_spi_ids[] = { 707 { .name = "bh2228fv" }, 708 { .name = "dh2228fv" }, 709 { .name = "jg10309-01" }, 710 { .name = "ltc2488" }, 711 { .name = "sx1301" }, 712 { .name = "bk4" }, 713 { .name = "dhcom-board" }, 714 { .name = "m53cpld" }, 715 { .name = "spi-petra" }, 716 { .name = "spi-authenta" }, 717 { .name = "em3581" }, 718 { .name = "si3210" }, 719 {}, 720 }; 721 MODULE_DEVICE_TABLE(spi, spidev_spi_ids); 722 723 /* 724 * spidev should never be referenced in DT without a specific compatible string, 725 * it is a Linux implementation thing rather than a description of the hardware. 726 */ spidev_of_check(struct device * dev)727 static int spidev_of_check(struct device *dev) 728 { 729 if (device_property_match_string(dev, "compatible", "spidev") < 0) 730 return 0; 731 732 dev_err(dev, "spidev listed directly in DT is not supported\n"); 733 return -EINVAL; 734 } 735 736 static const struct of_device_id spidev_dt_ids[] = { 737 { .compatible = "cisco,spi-petra", .data = &spidev_of_check }, 738 { .compatible = "dh,dhcom-board", .data = &spidev_of_check }, 739 { .compatible = "elgin,jg10309-01", .data = &spidev_of_check }, 740 { .compatible = "lineartechnology,ltc2488", .data = &spidev_of_check }, 741 { .compatible = "lwn,bk4", .data = &spidev_of_check }, 742 { .compatible = "menlo,m53cpld", .data = &spidev_of_check }, 743 { .compatible = "micron,spi-authenta", .data = &spidev_of_check }, 744 { .compatible = "rohm,bh2228fv", .data = &spidev_of_check }, 745 { .compatible = "rohm,dh2228fv", .data = &spidev_of_check }, 746 { .compatible = "semtech,sx1301", .data = &spidev_of_check }, 747 { .compatible = "silabs,em3581", .data = &spidev_of_check }, 748 { .compatible = "silabs,si3210", .data = &spidev_of_check }, 749 {}, 750 }; 751 MODULE_DEVICE_TABLE(of, spidev_dt_ids); 752 753 /* Dummy SPI devices not to be used in production systems */ spidev_acpi_check(struct device * dev)754 static int spidev_acpi_check(struct device *dev) 755 { 756 dev_warn(dev, "do not use this driver in production systems!\n"); 757 return 0; 758 } 759 760 static const struct acpi_device_id spidev_acpi_ids[] = { 761 /* 762 * The ACPI SPT000* devices are only meant for development and 763 * testing. Systems used in production should have a proper ACPI 764 * description of the connected peripheral and they should also use 765 * a proper driver instead of poking directly to the SPI bus. 766 */ 767 { "SPT0001", (kernel_ulong_t)&spidev_acpi_check }, 768 { "SPT0002", (kernel_ulong_t)&spidev_acpi_check }, 769 { "SPT0003", (kernel_ulong_t)&spidev_acpi_check }, 770 {}, 771 }; 772 MODULE_DEVICE_TABLE(acpi, spidev_acpi_ids); 773 774 /*-------------------------------------------------------------------------*/ 775 spidev_probe(struct spi_device * spi)776 static int spidev_probe(struct spi_device *spi) 777 { 778 int (*match)(struct device *dev); 779 struct spidev_data *spidev; 780 int status; 781 unsigned long minor; 782 783 match = device_get_match_data(&spi->dev); 784 if (match) { 785 status = match(&spi->dev); 786 if (status) 787 return status; 788 } 789 790 /* Allocate driver data */ 791 spidev = kzalloc(sizeof(*spidev), GFP_KERNEL); 792 if (!spidev) 793 return -ENOMEM; 794 795 /* Initialize the driver data */ 796 spidev->spi = spi; 797 mutex_init(&spidev->spi_lock); 798 mutex_init(&spidev->buf_lock); 799 800 INIT_LIST_HEAD(&spidev->device_entry); 801 802 /* If we can allocate a minor number, hook up this device. 803 * Reusing minors is fine so long as udev or mdev is working. 804 */ 805 mutex_lock(&device_list_lock); 806 minor = find_first_zero_bit(minors, N_SPI_MINORS); 807 if (minor < N_SPI_MINORS) { 808 struct device *dev; 809 810 spidev->devt = MKDEV(SPIDEV_MAJOR, minor); 811 dev = device_create(spidev_class, &spi->dev, spidev->devt, 812 spidev, "spidev%d.%d", 813 spi->master->bus_num, spi_get_chipselect(spi, 0)); 814 status = PTR_ERR_OR_ZERO(dev); 815 } else { 816 dev_dbg(&spi->dev, "no minor number available!\n"); 817 status = -ENODEV; 818 } 819 if (status == 0) { 820 set_bit(minor, minors); 821 list_add(&spidev->device_entry, &device_list); 822 } 823 mutex_unlock(&device_list_lock); 824 825 spidev->speed_hz = spi->max_speed_hz; 826 827 if (status == 0) 828 spi_set_drvdata(spi, spidev); 829 else 830 kfree(spidev); 831 832 return status; 833 } 834 spidev_remove(struct spi_device * spi)835 static void spidev_remove(struct spi_device *spi) 836 { 837 struct spidev_data *spidev = spi_get_drvdata(spi); 838 839 /* prevent new opens */ 840 mutex_lock(&device_list_lock); 841 /* make sure ops on existing fds can abort cleanly */ 842 mutex_lock(&spidev->spi_lock); 843 spidev->spi = NULL; 844 mutex_unlock(&spidev->spi_lock); 845 846 list_del(&spidev->device_entry); 847 device_destroy(spidev_class, spidev->devt); 848 clear_bit(MINOR(spidev->devt), minors); 849 if (spidev->users == 0) 850 kfree(spidev); 851 mutex_unlock(&device_list_lock); 852 } 853 854 static struct spi_driver spidev_spi_driver = { 855 .driver = { 856 .name = "spidev", 857 .of_match_table = spidev_dt_ids, 858 .acpi_match_table = spidev_acpi_ids, 859 }, 860 .probe = spidev_probe, 861 .remove = spidev_remove, 862 .id_table = spidev_spi_ids, 863 864 /* NOTE: suspend/resume methods are not necessary here. 865 * We don't do anything except pass the requests to/from 866 * the underlying controller. The refrigerator handles 867 * most issues; the controller driver handles the rest. 868 */ 869 }; 870 871 /*-------------------------------------------------------------------------*/ 872 spidev_init(void)873 static int __init spidev_init(void) 874 { 875 int status; 876 877 /* Claim our 256 reserved device numbers. Then register a class 878 * that will key udev/mdev to add/remove /dev nodes. Last, register 879 * the driver which manages those device numbers. 880 */ 881 status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops); 882 if (status < 0) 883 return status; 884 885 spidev_class = class_create("spidev"); 886 if (IS_ERR(spidev_class)) { 887 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name); 888 return PTR_ERR(spidev_class); 889 } 890 891 status = spi_register_driver(&spidev_spi_driver); 892 if (status < 0) { 893 class_destroy(spidev_class); 894 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name); 895 } 896 return status; 897 } 898 module_init(spidev_init); 899 spidev_exit(void)900 static void __exit spidev_exit(void) 901 { 902 spi_unregister_driver(&spidev_spi_driver); 903 class_destroy(spidev_class); 904 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name); 905 } 906 module_exit(spidev_exit); 907 908 MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>"); 909 MODULE_DESCRIPTION("User mode SPI device interface"); 910 MODULE_LICENSE("GPL"); 911 MODULE_ALIAS("spi:spidev"); 912