1 /* 2 * Simple synchronous userspace interface to SPI devices 3 * 4 * Copyright (C) 2006 SWAPP 5 * Andrea Paterniani <a.paterniani@swapp-eng.it> 6 * Copyright (C) 2007 David Brownell (simplification, cleanup) 7 * 8 * This program is free software; you can redistribute it and/or modify 9 * it under the terms of the GNU General Public License as published by 10 * the Free Software Foundation; either version 2 of the License, or 11 * (at your option) any later version. 12 * 13 * This program is distributed in the hope that it will be useful, 14 * but WITHOUT ANY WARRANTY; without even the implied warranty of 15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 * GNU General Public License for more details. 17 */ 18 19 #include <linux/init.h> 20 #include <linux/module.h> 21 #include <linux/ioctl.h> 22 #include <linux/fs.h> 23 #include <linux/device.h> 24 #include <linux/err.h> 25 #include <linux/list.h> 26 #include <linux/errno.h> 27 #include <linux/mutex.h> 28 #include <linux/slab.h> 29 #include <linux/compat.h> 30 #include <linux/of.h> 31 #include <linux/of_device.h> 32 #include <linux/acpi.h> 33 34 #include <linux/spi/spi.h> 35 #include <linux/spi/spidev.h> 36 37 #include <linux/uaccess.h> 38 39 40 /* 41 * This supports access to SPI devices using normal userspace I/O calls. 42 * Note that while traditional UNIX/POSIX I/O semantics are half duplex, 43 * and often mask message boundaries, full SPI support requires full duplex 44 * transfers. There are several kinds of internal message boundaries to 45 * handle chipselect management and other protocol options. 46 * 47 * SPI has a character major number assigned. We allocate minor numbers 48 * dynamically using a bitmask. You must use hotplug tools, such as udev 49 * (or mdev with busybox) to create and destroy the /dev/spidevB.C device 50 * nodes, since there is no fixed association of minor numbers with any 51 * particular SPI bus or device. 52 */ 53 #define SPIDEV_MAJOR 153 /* assigned */ 54 #define N_SPI_MINORS 32 /* ... up to 256 */ 55 56 static DECLARE_BITMAP(minors, N_SPI_MINORS); 57 58 59 /* Bit masks for spi_device.mode management. Note that incorrect 60 * settings for some settings can cause *lots* of trouble for other 61 * devices on a shared bus: 62 * 63 * - CS_HIGH ... this device will be active when it shouldn't be 64 * - 3WIRE ... when active, it won't behave as it should 65 * - NO_CS ... there will be no explicit message boundaries; this 66 * is completely incompatible with the shared bus model 67 * - READY ... transfers may proceed when they shouldn't. 68 * 69 * REVISIT should changing those flags be privileged? 70 */ 71 #define SPI_MODE_MASK (SPI_CPHA | SPI_CPOL | SPI_CS_HIGH \ 72 | SPI_LSB_FIRST | SPI_3WIRE | SPI_LOOP \ 73 | SPI_NO_CS | SPI_READY | SPI_TX_DUAL \ 74 | SPI_TX_QUAD | SPI_RX_DUAL | SPI_RX_QUAD) 75 76 struct spidev_data { 77 dev_t devt; 78 spinlock_t spi_lock; 79 struct spi_device *spi; 80 struct list_head device_entry; 81 82 /* TX/RX buffers are NULL unless this device is open (users > 0) */ 83 struct mutex buf_lock; 84 unsigned users; 85 u8 *tx_buffer; 86 u8 *rx_buffer; 87 u32 speed_hz; 88 }; 89 90 static LIST_HEAD(device_list); 91 static DEFINE_MUTEX(device_list_lock); 92 93 static unsigned bufsiz = 4096; 94 module_param(bufsiz, uint, S_IRUGO); 95 MODULE_PARM_DESC(bufsiz, "data bytes in biggest supported SPI message"); 96 97 /*-------------------------------------------------------------------------*/ 98 99 static ssize_t 100 spidev_sync(struct spidev_data *spidev, struct spi_message *message) 101 { 102 int status; 103 struct spi_device *spi; 104 105 spin_lock_irq(&spidev->spi_lock); 106 spi = spidev->spi; 107 spin_unlock_irq(&spidev->spi_lock); 108 109 if (spi == NULL) 110 status = -ESHUTDOWN; 111 else 112 status = spi_sync(spi, message); 113 114 if (status == 0) 115 status = message->actual_length; 116 117 return status; 118 } 119 120 static inline ssize_t 121 spidev_sync_write(struct spidev_data *spidev, size_t len) 122 { 123 struct spi_transfer t = { 124 .tx_buf = spidev->tx_buffer, 125 .len = len, 126 .speed_hz = spidev->speed_hz, 127 }; 128 struct spi_message m; 129 130 spi_message_init(&m); 131 spi_message_add_tail(&t, &m); 132 return spidev_sync(spidev, &m); 133 } 134 135 static inline ssize_t 136 spidev_sync_read(struct spidev_data *spidev, size_t len) 137 { 138 struct spi_transfer t = { 139 .rx_buf = spidev->rx_buffer, 140 .len = len, 141 .speed_hz = spidev->speed_hz, 142 }; 143 struct spi_message m; 144 145 spi_message_init(&m); 146 spi_message_add_tail(&t, &m); 147 return spidev_sync(spidev, &m); 148 } 149 150 /*-------------------------------------------------------------------------*/ 151 152 /* Read-only message with current device setup */ 153 static ssize_t 154 spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos) 155 { 156 struct spidev_data *spidev; 157 ssize_t status = 0; 158 159 /* chipselect only toggles at start or end of operation */ 160 if (count > bufsiz) 161 return -EMSGSIZE; 162 163 spidev = filp->private_data; 164 165 mutex_lock(&spidev->buf_lock); 166 status = spidev_sync_read(spidev, count); 167 if (status > 0) { 168 unsigned long missing; 169 170 missing = copy_to_user(buf, spidev->rx_buffer, status); 171 if (missing == status) 172 status = -EFAULT; 173 else 174 status = status - missing; 175 } 176 mutex_unlock(&spidev->buf_lock); 177 178 return status; 179 } 180 181 /* Write-only message with current device setup */ 182 static ssize_t 183 spidev_write(struct file *filp, const char __user *buf, 184 size_t count, loff_t *f_pos) 185 { 186 struct spidev_data *spidev; 187 ssize_t status = 0; 188 unsigned long missing; 189 190 /* chipselect only toggles at start or end of operation */ 191 if (count > bufsiz) 192 return -EMSGSIZE; 193 194 spidev = filp->private_data; 195 196 mutex_lock(&spidev->buf_lock); 197 missing = copy_from_user(spidev->tx_buffer, buf, count); 198 if (missing == 0) 199 status = spidev_sync_write(spidev, count); 200 else 201 status = -EFAULT; 202 mutex_unlock(&spidev->buf_lock); 203 204 return status; 205 } 206 207 static int spidev_message(struct spidev_data *spidev, 208 struct spi_ioc_transfer *u_xfers, unsigned n_xfers) 209 { 210 struct spi_message msg; 211 struct spi_transfer *k_xfers; 212 struct spi_transfer *k_tmp; 213 struct spi_ioc_transfer *u_tmp; 214 unsigned n, total, tx_total, rx_total; 215 u8 *tx_buf, *rx_buf; 216 int status = -EFAULT; 217 218 spi_message_init(&msg); 219 k_xfers = kcalloc(n_xfers, sizeof(*k_tmp), GFP_KERNEL); 220 if (k_xfers == NULL) 221 return -ENOMEM; 222 223 /* Construct spi_message, copying any tx data to bounce buffer. 224 * We walk the array of user-provided transfers, using each one 225 * to initialize a kernel version of the same transfer. 226 */ 227 tx_buf = spidev->tx_buffer; 228 rx_buf = spidev->rx_buffer; 229 total = 0; 230 tx_total = 0; 231 rx_total = 0; 232 for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers; 233 n; 234 n--, k_tmp++, u_tmp++) { 235 k_tmp->len = u_tmp->len; 236 237 total += k_tmp->len; 238 /* Since the function returns the total length of transfers 239 * on success, restrict the total to positive int values to 240 * avoid the return value looking like an error. Also check 241 * each transfer length to avoid arithmetic overflow. 242 */ 243 if (total > INT_MAX || k_tmp->len > INT_MAX) { 244 status = -EMSGSIZE; 245 goto done; 246 } 247 248 if (u_tmp->rx_buf) { 249 /* this transfer needs space in RX bounce buffer */ 250 rx_total += k_tmp->len; 251 if (rx_total > bufsiz) { 252 status = -EMSGSIZE; 253 goto done; 254 } 255 k_tmp->rx_buf = rx_buf; 256 rx_buf += k_tmp->len; 257 } 258 if (u_tmp->tx_buf) { 259 /* this transfer needs space in TX bounce buffer */ 260 tx_total += k_tmp->len; 261 if (tx_total > bufsiz) { 262 status = -EMSGSIZE; 263 goto done; 264 } 265 k_tmp->tx_buf = tx_buf; 266 if (copy_from_user(tx_buf, (const u8 __user *) 267 (uintptr_t) u_tmp->tx_buf, 268 u_tmp->len)) 269 goto done; 270 tx_buf += k_tmp->len; 271 } 272 273 k_tmp->cs_change = !!u_tmp->cs_change; 274 k_tmp->tx_nbits = u_tmp->tx_nbits; 275 k_tmp->rx_nbits = u_tmp->rx_nbits; 276 k_tmp->bits_per_word = u_tmp->bits_per_word; 277 k_tmp->delay_usecs = u_tmp->delay_usecs; 278 k_tmp->speed_hz = u_tmp->speed_hz; 279 k_tmp->word_delay_usecs = u_tmp->word_delay_usecs; 280 if (!k_tmp->speed_hz) 281 k_tmp->speed_hz = spidev->speed_hz; 282 #ifdef VERBOSE 283 dev_dbg(&spidev->spi->dev, 284 " xfer len %u %s%s%s%dbits %u usec %u usec %uHz\n", 285 u_tmp->len, 286 u_tmp->rx_buf ? "rx " : "", 287 u_tmp->tx_buf ? "tx " : "", 288 u_tmp->cs_change ? "cs " : "", 289 u_tmp->bits_per_word ? : spidev->spi->bits_per_word, 290 u_tmp->delay_usecs, 291 u_tmp->word_delay_usecs, 292 u_tmp->speed_hz ? : spidev->spi->max_speed_hz); 293 #endif 294 spi_message_add_tail(k_tmp, &msg); 295 } 296 297 status = spidev_sync(spidev, &msg); 298 if (status < 0) 299 goto done; 300 301 /* copy any rx data out of bounce buffer */ 302 rx_buf = spidev->rx_buffer; 303 for (n = n_xfers, u_tmp = u_xfers; n; n--, u_tmp++) { 304 if (u_tmp->rx_buf) { 305 if (copy_to_user((u8 __user *) 306 (uintptr_t) u_tmp->rx_buf, rx_buf, 307 u_tmp->len)) { 308 status = -EFAULT; 309 goto done; 310 } 311 rx_buf += u_tmp->len; 312 } 313 } 314 status = total; 315 316 done: 317 kfree(k_xfers); 318 return status; 319 } 320 321 static struct spi_ioc_transfer * 322 spidev_get_ioc_message(unsigned int cmd, struct spi_ioc_transfer __user *u_ioc, 323 unsigned *n_ioc) 324 { 325 u32 tmp; 326 327 /* Check type, command number and direction */ 328 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC 329 || _IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0)) 330 || _IOC_DIR(cmd) != _IOC_WRITE) 331 return ERR_PTR(-ENOTTY); 332 333 tmp = _IOC_SIZE(cmd); 334 if ((tmp % sizeof(struct spi_ioc_transfer)) != 0) 335 return ERR_PTR(-EINVAL); 336 *n_ioc = tmp / sizeof(struct spi_ioc_transfer); 337 if (*n_ioc == 0) 338 return NULL; 339 340 /* copy into scratch area */ 341 return memdup_user(u_ioc, tmp); 342 } 343 344 static long 345 spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) 346 { 347 int retval = 0; 348 struct spidev_data *spidev; 349 struct spi_device *spi; 350 u32 tmp; 351 unsigned n_ioc; 352 struct spi_ioc_transfer *ioc; 353 354 /* Check type and command number */ 355 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC) 356 return -ENOTTY; 357 358 /* guard against device removal before, or while, 359 * we issue this ioctl. 360 */ 361 spidev = filp->private_data; 362 spin_lock_irq(&spidev->spi_lock); 363 spi = spi_dev_get(spidev->spi); 364 spin_unlock_irq(&spidev->spi_lock); 365 366 if (spi == NULL) 367 return -ESHUTDOWN; 368 369 /* use the buffer lock here for triple duty: 370 * - prevent I/O (from us) so calling spi_setup() is safe; 371 * - prevent concurrent SPI_IOC_WR_* from morphing 372 * data fields while SPI_IOC_RD_* reads them; 373 * - SPI_IOC_MESSAGE needs the buffer locked "normally". 374 */ 375 mutex_lock(&spidev->buf_lock); 376 377 switch (cmd) { 378 /* read requests */ 379 case SPI_IOC_RD_MODE: 380 retval = put_user(spi->mode & SPI_MODE_MASK, 381 (__u8 __user *)arg); 382 break; 383 case SPI_IOC_RD_MODE32: 384 retval = put_user(spi->mode & SPI_MODE_MASK, 385 (__u32 __user *)arg); 386 break; 387 case SPI_IOC_RD_LSB_FIRST: 388 retval = put_user((spi->mode & SPI_LSB_FIRST) ? 1 : 0, 389 (__u8 __user *)arg); 390 break; 391 case SPI_IOC_RD_BITS_PER_WORD: 392 retval = put_user(spi->bits_per_word, (__u8 __user *)arg); 393 break; 394 case SPI_IOC_RD_MAX_SPEED_HZ: 395 retval = put_user(spidev->speed_hz, (__u32 __user *)arg); 396 break; 397 398 /* write requests */ 399 case SPI_IOC_WR_MODE: 400 case SPI_IOC_WR_MODE32: 401 if (cmd == SPI_IOC_WR_MODE) 402 retval = get_user(tmp, (u8 __user *)arg); 403 else 404 retval = get_user(tmp, (u32 __user *)arg); 405 if (retval == 0) { 406 u32 save = spi->mode; 407 408 if (tmp & ~SPI_MODE_MASK) { 409 retval = -EINVAL; 410 break; 411 } 412 413 tmp |= spi->mode & ~SPI_MODE_MASK; 414 spi->mode = (u16)tmp; 415 retval = spi_setup(spi); 416 if (retval < 0) 417 spi->mode = save; 418 else 419 dev_dbg(&spi->dev, "spi mode %x\n", tmp); 420 } 421 break; 422 case SPI_IOC_WR_LSB_FIRST: 423 retval = get_user(tmp, (__u8 __user *)arg); 424 if (retval == 0) { 425 u32 save = spi->mode; 426 427 if (tmp) 428 spi->mode |= SPI_LSB_FIRST; 429 else 430 spi->mode &= ~SPI_LSB_FIRST; 431 retval = spi_setup(spi); 432 if (retval < 0) 433 spi->mode = save; 434 else 435 dev_dbg(&spi->dev, "%csb first\n", 436 tmp ? 'l' : 'm'); 437 } 438 break; 439 case SPI_IOC_WR_BITS_PER_WORD: 440 retval = get_user(tmp, (__u8 __user *)arg); 441 if (retval == 0) { 442 u8 save = spi->bits_per_word; 443 444 spi->bits_per_word = tmp; 445 retval = spi_setup(spi); 446 if (retval < 0) 447 spi->bits_per_word = save; 448 else 449 dev_dbg(&spi->dev, "%d bits per word\n", tmp); 450 } 451 break; 452 case SPI_IOC_WR_MAX_SPEED_HZ: 453 retval = get_user(tmp, (__u32 __user *)arg); 454 if (retval == 0) { 455 u32 save = spi->max_speed_hz; 456 457 spi->max_speed_hz = tmp; 458 retval = spi_setup(spi); 459 if (retval >= 0) 460 spidev->speed_hz = tmp; 461 else 462 dev_dbg(&spi->dev, "%d Hz (max)\n", tmp); 463 spi->max_speed_hz = save; 464 } 465 break; 466 467 default: 468 /* segmented and/or full-duplex I/O request */ 469 /* Check message and copy into scratch area */ 470 ioc = spidev_get_ioc_message(cmd, 471 (struct spi_ioc_transfer __user *)arg, &n_ioc); 472 if (IS_ERR(ioc)) { 473 retval = PTR_ERR(ioc); 474 break; 475 } 476 if (!ioc) 477 break; /* n_ioc is also 0 */ 478 479 /* translate to spi_message, execute */ 480 retval = spidev_message(spidev, ioc, n_ioc); 481 kfree(ioc); 482 break; 483 } 484 485 mutex_unlock(&spidev->buf_lock); 486 spi_dev_put(spi); 487 return retval; 488 } 489 490 #ifdef CONFIG_COMPAT 491 static long 492 spidev_compat_ioc_message(struct file *filp, unsigned int cmd, 493 unsigned long arg) 494 { 495 struct spi_ioc_transfer __user *u_ioc; 496 int retval = 0; 497 struct spidev_data *spidev; 498 struct spi_device *spi; 499 unsigned n_ioc, n; 500 struct spi_ioc_transfer *ioc; 501 502 u_ioc = (struct spi_ioc_transfer __user *) compat_ptr(arg); 503 504 /* guard against device removal before, or while, 505 * we issue this ioctl. 506 */ 507 spidev = filp->private_data; 508 spin_lock_irq(&spidev->spi_lock); 509 spi = spi_dev_get(spidev->spi); 510 spin_unlock_irq(&spidev->spi_lock); 511 512 if (spi == NULL) 513 return -ESHUTDOWN; 514 515 /* SPI_IOC_MESSAGE needs the buffer locked "normally" */ 516 mutex_lock(&spidev->buf_lock); 517 518 /* Check message and copy into scratch area */ 519 ioc = spidev_get_ioc_message(cmd, u_ioc, &n_ioc); 520 if (IS_ERR(ioc)) { 521 retval = PTR_ERR(ioc); 522 goto done; 523 } 524 if (!ioc) 525 goto done; /* n_ioc is also 0 */ 526 527 /* Convert buffer pointers */ 528 for (n = 0; n < n_ioc; n++) { 529 ioc[n].rx_buf = (uintptr_t) compat_ptr(ioc[n].rx_buf); 530 ioc[n].tx_buf = (uintptr_t) compat_ptr(ioc[n].tx_buf); 531 } 532 533 /* translate to spi_message, execute */ 534 retval = spidev_message(spidev, ioc, n_ioc); 535 kfree(ioc); 536 537 done: 538 mutex_unlock(&spidev->buf_lock); 539 spi_dev_put(spi); 540 return retval; 541 } 542 543 static long 544 spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) 545 { 546 if (_IOC_TYPE(cmd) == SPI_IOC_MAGIC 547 && _IOC_NR(cmd) == _IOC_NR(SPI_IOC_MESSAGE(0)) 548 && _IOC_DIR(cmd) == _IOC_WRITE) 549 return spidev_compat_ioc_message(filp, cmd, arg); 550 551 return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg)); 552 } 553 #else 554 #define spidev_compat_ioctl NULL 555 #endif /* CONFIG_COMPAT */ 556 557 static int spidev_open(struct inode *inode, struct file *filp) 558 { 559 struct spidev_data *spidev; 560 int status = -ENXIO; 561 562 mutex_lock(&device_list_lock); 563 564 list_for_each_entry(spidev, &device_list, device_entry) { 565 if (spidev->devt == inode->i_rdev) { 566 status = 0; 567 break; 568 } 569 } 570 571 if (status) { 572 pr_debug("spidev: nothing for minor %d\n", iminor(inode)); 573 goto err_find_dev; 574 } 575 576 if (!spidev->tx_buffer) { 577 spidev->tx_buffer = kmalloc(bufsiz, GFP_KERNEL); 578 if (!spidev->tx_buffer) { 579 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n"); 580 status = -ENOMEM; 581 goto err_find_dev; 582 } 583 } 584 585 if (!spidev->rx_buffer) { 586 spidev->rx_buffer = kmalloc(bufsiz, GFP_KERNEL); 587 if (!spidev->rx_buffer) { 588 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n"); 589 status = -ENOMEM; 590 goto err_alloc_rx_buf; 591 } 592 } 593 594 spidev->users++; 595 filp->private_data = spidev; 596 stream_open(inode, filp); 597 598 mutex_unlock(&device_list_lock); 599 return 0; 600 601 err_alloc_rx_buf: 602 kfree(spidev->tx_buffer); 603 spidev->tx_buffer = NULL; 604 err_find_dev: 605 mutex_unlock(&device_list_lock); 606 return status; 607 } 608 609 static int spidev_release(struct inode *inode, struct file *filp) 610 { 611 struct spidev_data *spidev; 612 613 mutex_lock(&device_list_lock); 614 spidev = filp->private_data; 615 filp->private_data = NULL; 616 617 /* last close? */ 618 spidev->users--; 619 if (!spidev->users) { 620 int dofree; 621 622 kfree(spidev->tx_buffer); 623 spidev->tx_buffer = NULL; 624 625 kfree(spidev->rx_buffer); 626 spidev->rx_buffer = NULL; 627 628 spin_lock_irq(&spidev->spi_lock); 629 if (spidev->spi) 630 spidev->speed_hz = spidev->spi->max_speed_hz; 631 632 /* ... after we unbound from the underlying device? */ 633 dofree = (spidev->spi == NULL); 634 spin_unlock_irq(&spidev->spi_lock); 635 636 if (dofree) 637 kfree(spidev); 638 } 639 mutex_unlock(&device_list_lock); 640 641 return 0; 642 } 643 644 static const struct file_operations spidev_fops = { 645 .owner = THIS_MODULE, 646 /* REVISIT switch to aio primitives, so that userspace 647 * gets more complete API coverage. It'll simplify things 648 * too, except for the locking. 649 */ 650 .write = spidev_write, 651 .read = spidev_read, 652 .unlocked_ioctl = spidev_ioctl, 653 .compat_ioctl = spidev_compat_ioctl, 654 .open = spidev_open, 655 .release = spidev_release, 656 .llseek = no_llseek, 657 }; 658 659 /*-------------------------------------------------------------------------*/ 660 661 /* The main reason to have this class is to make mdev/udev create the 662 * /dev/spidevB.C character device nodes exposing our userspace API. 663 * It also simplifies memory management. 664 */ 665 666 static struct class *spidev_class; 667 668 #ifdef CONFIG_OF 669 static const struct of_device_id spidev_dt_ids[] = { 670 { .compatible = "rohm,dh2228fv" }, 671 { .compatible = "lineartechnology,ltc2488" }, 672 { .compatible = "ge,achc" }, 673 { .compatible = "semtech,sx1301" }, 674 { .compatible = "lwn,bk4" }, 675 {}, 676 }; 677 MODULE_DEVICE_TABLE(of, spidev_dt_ids); 678 #endif 679 680 #ifdef CONFIG_ACPI 681 682 /* Dummy SPI devices not to be used in production systems */ 683 #define SPIDEV_ACPI_DUMMY 1 684 685 static const struct acpi_device_id spidev_acpi_ids[] = { 686 /* 687 * The ACPI SPT000* devices are only meant for development and 688 * testing. Systems used in production should have a proper ACPI 689 * description of the connected peripheral and they should also use 690 * a proper driver instead of poking directly to the SPI bus. 691 */ 692 { "SPT0001", SPIDEV_ACPI_DUMMY }, 693 { "SPT0002", SPIDEV_ACPI_DUMMY }, 694 { "SPT0003", SPIDEV_ACPI_DUMMY }, 695 {}, 696 }; 697 MODULE_DEVICE_TABLE(acpi, spidev_acpi_ids); 698 699 static void spidev_probe_acpi(struct spi_device *spi) 700 { 701 const struct acpi_device_id *id; 702 703 if (!has_acpi_companion(&spi->dev)) 704 return; 705 706 id = acpi_match_device(spidev_acpi_ids, &spi->dev); 707 if (WARN_ON(!id)) 708 return; 709 710 if (id->driver_data == SPIDEV_ACPI_DUMMY) 711 dev_warn(&spi->dev, "do not use this driver in production systems!\n"); 712 } 713 #else 714 static inline void spidev_probe_acpi(struct spi_device *spi) {} 715 #endif 716 717 /*-------------------------------------------------------------------------*/ 718 719 static int spidev_probe(struct spi_device *spi) 720 { 721 struct spidev_data *spidev; 722 int status; 723 unsigned long minor; 724 725 /* 726 * spidev should never be referenced in DT without a specific 727 * compatible string, it is a Linux implementation thing 728 * rather than a description of the hardware. 729 */ 730 WARN(spi->dev.of_node && 731 of_device_is_compatible(spi->dev.of_node, "spidev"), 732 "%pOF: buggy DT: spidev listed directly in DT\n", spi->dev.of_node); 733 734 spidev_probe_acpi(spi); 735 736 /* Allocate driver data */ 737 spidev = kzalloc(sizeof(*spidev), GFP_KERNEL); 738 if (!spidev) 739 return -ENOMEM; 740 741 /* Initialize the driver data */ 742 spidev->spi = spi; 743 spin_lock_init(&spidev->spi_lock); 744 mutex_init(&spidev->buf_lock); 745 746 INIT_LIST_HEAD(&spidev->device_entry); 747 748 /* If we can allocate a minor number, hook up this device. 749 * Reusing minors is fine so long as udev or mdev is working. 750 */ 751 mutex_lock(&device_list_lock); 752 minor = find_first_zero_bit(minors, N_SPI_MINORS); 753 if (minor < N_SPI_MINORS) { 754 struct device *dev; 755 756 spidev->devt = MKDEV(SPIDEV_MAJOR, minor); 757 dev = device_create(spidev_class, &spi->dev, spidev->devt, 758 spidev, "spidev%d.%d", 759 spi->master->bus_num, spi->chip_select); 760 status = PTR_ERR_OR_ZERO(dev); 761 } else { 762 dev_dbg(&spi->dev, "no minor number available!\n"); 763 status = -ENODEV; 764 } 765 if (status == 0) { 766 set_bit(minor, minors); 767 list_add(&spidev->device_entry, &device_list); 768 } 769 mutex_unlock(&device_list_lock); 770 771 spidev->speed_hz = spi->max_speed_hz; 772 773 if (status == 0) 774 spi_set_drvdata(spi, spidev); 775 else 776 kfree(spidev); 777 778 return status; 779 } 780 781 static int spidev_remove(struct spi_device *spi) 782 { 783 struct spidev_data *spidev = spi_get_drvdata(spi); 784 785 /* make sure ops on existing fds can abort cleanly */ 786 spin_lock_irq(&spidev->spi_lock); 787 spidev->spi = NULL; 788 spin_unlock_irq(&spidev->spi_lock); 789 790 /* prevent new opens */ 791 mutex_lock(&device_list_lock); 792 list_del(&spidev->device_entry); 793 device_destroy(spidev_class, spidev->devt); 794 clear_bit(MINOR(spidev->devt), minors); 795 if (spidev->users == 0) 796 kfree(spidev); 797 mutex_unlock(&device_list_lock); 798 799 return 0; 800 } 801 802 static struct spi_driver spidev_spi_driver = { 803 .driver = { 804 .name = "spidev", 805 .of_match_table = of_match_ptr(spidev_dt_ids), 806 .acpi_match_table = ACPI_PTR(spidev_acpi_ids), 807 }, 808 .probe = spidev_probe, 809 .remove = spidev_remove, 810 811 /* NOTE: suspend/resume methods are not necessary here. 812 * We don't do anything except pass the requests to/from 813 * the underlying controller. The refrigerator handles 814 * most issues; the controller driver handles the rest. 815 */ 816 }; 817 818 /*-------------------------------------------------------------------------*/ 819 820 static int __init spidev_init(void) 821 { 822 int status; 823 824 /* Claim our 256 reserved device numbers. Then register a class 825 * that will key udev/mdev to add/remove /dev nodes. Last, register 826 * the driver which manages those device numbers. 827 */ 828 BUILD_BUG_ON(N_SPI_MINORS > 256); 829 status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops); 830 if (status < 0) 831 return status; 832 833 spidev_class = class_create(THIS_MODULE, "spidev"); 834 if (IS_ERR(spidev_class)) { 835 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name); 836 return PTR_ERR(spidev_class); 837 } 838 839 status = spi_register_driver(&spidev_spi_driver); 840 if (status < 0) { 841 class_destroy(spidev_class); 842 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name); 843 } 844 return status; 845 } 846 module_init(spidev_init); 847 848 static void __exit spidev_exit(void) 849 { 850 spi_unregister_driver(&spidev_spi_driver); 851 class_destroy(spidev_class); 852 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name); 853 } 854 module_exit(spidev_exit); 855 856 MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>"); 857 MODULE_DESCRIPTION("User mode SPI device interface"); 858 MODULE_LICENSE("GPL"); 859 MODULE_ALIAS("spi:spidev"); 860