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 if (!k_tmp->speed_hz) 280 k_tmp->speed_hz = spidev->speed_hz; 281 #ifdef VERBOSE 282 dev_dbg(&spidev->spi->dev, 283 " xfer len %u %s%s%s%dbits %u usec %uHz\n", 284 u_tmp->len, 285 u_tmp->rx_buf ? "rx " : "", 286 u_tmp->tx_buf ? "tx " : "", 287 u_tmp->cs_change ? "cs " : "", 288 u_tmp->bits_per_word ? : spidev->spi->bits_per_word, 289 u_tmp->delay_usecs, 290 u_tmp->speed_hz ? : spidev->spi->max_speed_hz); 291 #endif 292 spi_message_add_tail(k_tmp, &msg); 293 } 294 295 status = spidev_sync(spidev, &msg); 296 if (status < 0) 297 goto done; 298 299 /* copy any rx data out of bounce buffer */ 300 rx_buf = spidev->rx_buffer; 301 for (n = n_xfers, u_tmp = u_xfers; n; n--, u_tmp++) { 302 if (u_tmp->rx_buf) { 303 if (copy_to_user((u8 __user *) 304 (uintptr_t) u_tmp->rx_buf, rx_buf, 305 u_tmp->len)) { 306 status = -EFAULT; 307 goto done; 308 } 309 rx_buf += u_tmp->len; 310 } 311 } 312 status = total; 313 314 done: 315 kfree(k_xfers); 316 return status; 317 } 318 319 static struct spi_ioc_transfer * 320 spidev_get_ioc_message(unsigned int cmd, struct spi_ioc_transfer __user *u_ioc, 321 unsigned *n_ioc) 322 { 323 u32 tmp; 324 325 /* Check type, command number and direction */ 326 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC 327 || _IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0)) 328 || _IOC_DIR(cmd) != _IOC_WRITE) 329 return ERR_PTR(-ENOTTY); 330 331 tmp = _IOC_SIZE(cmd); 332 if ((tmp % sizeof(struct spi_ioc_transfer)) != 0) 333 return ERR_PTR(-EINVAL); 334 *n_ioc = tmp / sizeof(struct spi_ioc_transfer); 335 if (*n_ioc == 0) 336 return NULL; 337 338 /* copy into scratch area */ 339 return memdup_user(u_ioc, tmp); 340 } 341 342 static long 343 spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) 344 { 345 int retval = 0; 346 struct spidev_data *spidev; 347 struct spi_device *spi; 348 u32 tmp; 349 unsigned n_ioc; 350 struct spi_ioc_transfer *ioc; 351 352 /* Check type and command number */ 353 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC) 354 return -ENOTTY; 355 356 /* guard against device removal before, or while, 357 * we issue this ioctl. 358 */ 359 spidev = filp->private_data; 360 spin_lock_irq(&spidev->spi_lock); 361 spi = spi_dev_get(spidev->spi); 362 spin_unlock_irq(&spidev->spi_lock); 363 364 if (spi == NULL) 365 return -ESHUTDOWN; 366 367 /* use the buffer lock here for triple duty: 368 * - prevent I/O (from us) so calling spi_setup() is safe; 369 * - prevent concurrent SPI_IOC_WR_* from morphing 370 * data fields while SPI_IOC_RD_* reads them; 371 * - SPI_IOC_MESSAGE needs the buffer locked "normally". 372 */ 373 mutex_lock(&spidev->buf_lock); 374 375 switch (cmd) { 376 /* read requests */ 377 case SPI_IOC_RD_MODE: 378 retval = put_user(spi->mode & SPI_MODE_MASK, 379 (__u8 __user *)arg); 380 break; 381 case SPI_IOC_RD_MODE32: 382 retval = put_user(spi->mode & SPI_MODE_MASK, 383 (__u32 __user *)arg); 384 break; 385 case SPI_IOC_RD_LSB_FIRST: 386 retval = put_user((spi->mode & SPI_LSB_FIRST) ? 1 : 0, 387 (__u8 __user *)arg); 388 break; 389 case SPI_IOC_RD_BITS_PER_WORD: 390 retval = put_user(spi->bits_per_word, (__u8 __user *)arg); 391 break; 392 case SPI_IOC_RD_MAX_SPEED_HZ: 393 retval = put_user(spidev->speed_hz, (__u32 __user *)arg); 394 break; 395 396 /* write requests */ 397 case SPI_IOC_WR_MODE: 398 case SPI_IOC_WR_MODE32: 399 if (cmd == SPI_IOC_WR_MODE) 400 retval = get_user(tmp, (u8 __user *)arg); 401 else 402 retval = get_user(tmp, (u32 __user *)arg); 403 if (retval == 0) { 404 u32 save = spi->mode; 405 406 if (tmp & ~SPI_MODE_MASK) { 407 retval = -EINVAL; 408 break; 409 } 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 nonseekable_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 mutex_unlock(&device_list_lock); 638 639 return 0; 640 } 641 642 static const struct file_operations spidev_fops = { 643 .owner = THIS_MODULE, 644 /* REVISIT switch to aio primitives, so that userspace 645 * gets more complete API coverage. It'll simplify things 646 * too, except for the locking. 647 */ 648 .write = spidev_write, 649 .read = spidev_read, 650 .unlocked_ioctl = spidev_ioctl, 651 .compat_ioctl = spidev_compat_ioctl, 652 .open = spidev_open, 653 .release = spidev_release, 654 .llseek = no_llseek, 655 }; 656 657 /*-------------------------------------------------------------------------*/ 658 659 /* The main reason to have this class is to make mdev/udev create the 660 * /dev/spidevB.C character device nodes exposing our userspace API. 661 * It also simplifies memory management. 662 */ 663 664 static struct class *spidev_class; 665 666 #ifdef CONFIG_OF 667 static const struct of_device_id spidev_dt_ids[] = { 668 { .compatible = "rohm,dh2228fv" }, 669 { .compatible = "lineartechnology,ltc2488" }, 670 { .compatible = "ge,achc" }, 671 { .compatible = "semtech,sx1301" }, 672 {}, 673 }; 674 MODULE_DEVICE_TABLE(of, spidev_dt_ids); 675 #endif 676 677 #ifdef CONFIG_ACPI 678 679 /* Dummy SPI devices not to be used in production systems */ 680 #define SPIDEV_ACPI_DUMMY 1 681 682 static const struct acpi_device_id spidev_acpi_ids[] = { 683 /* 684 * The ACPI SPT000* devices are only meant for development and 685 * testing. Systems used in production should have a proper ACPI 686 * description of the connected peripheral and they should also use 687 * a proper driver instead of poking directly to the SPI bus. 688 */ 689 { "SPT0001", SPIDEV_ACPI_DUMMY }, 690 { "SPT0002", SPIDEV_ACPI_DUMMY }, 691 { "SPT0003", SPIDEV_ACPI_DUMMY }, 692 {}, 693 }; 694 MODULE_DEVICE_TABLE(acpi, spidev_acpi_ids); 695 696 static void spidev_probe_acpi(struct spi_device *spi) 697 { 698 const struct acpi_device_id *id; 699 700 if (!has_acpi_companion(&spi->dev)) 701 return; 702 703 id = acpi_match_device(spidev_acpi_ids, &spi->dev); 704 if (WARN_ON(!id)) 705 return; 706 707 if (id->driver_data == SPIDEV_ACPI_DUMMY) 708 dev_warn(&spi->dev, "do not use this driver in production systems!\n"); 709 } 710 #else 711 static inline void spidev_probe_acpi(struct spi_device *spi) {} 712 #endif 713 714 /*-------------------------------------------------------------------------*/ 715 716 static int spidev_probe(struct spi_device *spi) 717 { 718 struct spidev_data *spidev; 719 int status; 720 unsigned long minor; 721 722 /* 723 * spidev should never be referenced in DT without a specific 724 * compatible string, it is a Linux implementation thing 725 * rather than a description of the hardware. 726 */ 727 if (spi->dev.of_node && !of_match_device(spidev_dt_ids, &spi->dev)) { 728 dev_err(&spi->dev, "buggy DT: spidev listed directly in DT\n"); 729 WARN_ON(spi->dev.of_node && 730 !of_match_device(spidev_dt_ids, &spi->dev)); 731 } 732 733 spidev_probe_acpi(spi); 734 735 /* Allocate driver data */ 736 spidev = kzalloc(sizeof(*spidev), GFP_KERNEL); 737 if (!spidev) 738 return -ENOMEM; 739 740 /* Initialize the driver data */ 741 spidev->spi = spi; 742 spin_lock_init(&spidev->spi_lock); 743 mutex_init(&spidev->buf_lock); 744 745 INIT_LIST_HEAD(&spidev->device_entry); 746 747 /* If we can allocate a minor number, hook up this device. 748 * Reusing minors is fine so long as udev or mdev is working. 749 */ 750 mutex_lock(&device_list_lock); 751 minor = find_first_zero_bit(minors, N_SPI_MINORS); 752 if (minor < N_SPI_MINORS) { 753 struct device *dev; 754 755 spidev->devt = MKDEV(SPIDEV_MAJOR, minor); 756 dev = device_create(spidev_class, &spi->dev, spidev->devt, 757 spidev, "spidev%d.%d", 758 spi->master->bus_num, spi->chip_select); 759 status = PTR_ERR_OR_ZERO(dev); 760 } else { 761 dev_dbg(&spi->dev, "no minor number available!\n"); 762 status = -ENODEV; 763 } 764 if (status == 0) { 765 set_bit(minor, minors); 766 list_add(&spidev->device_entry, &device_list); 767 } 768 mutex_unlock(&device_list_lock); 769 770 spidev->speed_hz = spi->max_speed_hz; 771 772 if (status == 0) 773 spi_set_drvdata(spi, spidev); 774 else 775 kfree(spidev); 776 777 return status; 778 } 779 780 static int spidev_remove(struct spi_device *spi) 781 { 782 struct spidev_data *spidev = spi_get_drvdata(spi); 783 784 /* make sure ops on existing fds can abort cleanly */ 785 spin_lock_irq(&spidev->spi_lock); 786 spidev->spi = NULL; 787 spin_unlock_irq(&spidev->spi_lock); 788 789 /* prevent new opens */ 790 mutex_lock(&device_list_lock); 791 list_del(&spidev->device_entry); 792 device_destroy(spidev_class, spidev->devt); 793 clear_bit(MINOR(spidev->devt), minors); 794 if (spidev->users == 0) 795 kfree(spidev); 796 mutex_unlock(&device_list_lock); 797 798 return 0; 799 } 800 801 static struct spi_driver spidev_spi_driver = { 802 .driver = { 803 .name = "spidev", 804 .of_match_table = of_match_ptr(spidev_dt_ids), 805 .acpi_match_table = ACPI_PTR(spidev_acpi_ids), 806 }, 807 .probe = spidev_probe, 808 .remove = spidev_remove, 809 810 /* NOTE: suspend/resume methods are not necessary here. 811 * We don't do anything except pass the requests to/from 812 * the underlying controller. The refrigerator handles 813 * most issues; the controller driver handles the rest. 814 */ 815 }; 816 817 /*-------------------------------------------------------------------------*/ 818 819 static int __init spidev_init(void) 820 { 821 int status; 822 823 /* Claim our 256 reserved device numbers. Then register a class 824 * that will key udev/mdev to add/remove /dev nodes. Last, register 825 * the driver which manages those device numbers. 826 */ 827 BUILD_BUG_ON(N_SPI_MINORS > 256); 828 status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops); 829 if (status < 0) 830 return status; 831 832 spidev_class = class_create(THIS_MODULE, "spidev"); 833 if (IS_ERR(spidev_class)) { 834 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name); 835 return PTR_ERR(spidev_class); 836 } 837 838 status = spi_register_driver(&spidev_spi_driver); 839 if (status < 0) { 840 class_destroy(spidev_class); 841 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name); 842 } 843 return status; 844 } 845 module_init(spidev_init); 846 847 static void __exit spidev_exit(void) 848 { 849 spi_unregister_driver(&spidev_spi_driver); 850 class_destroy(spidev_class); 851 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name); 852 } 853 module_exit(spidev_exit); 854 855 MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>"); 856 MODULE_DESCRIPTION("User mode SPI device interface"); 857 MODULE_LICENSE("GPL"); 858 MODULE_ALIAS("spi:spidev"); 859