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 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
21 */
22
23 #include <linux/init.h>
24 #include <linux/module.h>
25 #include <linux/ioctl.h>
26 #include <linux/fs.h>
27 #include <linux/device.h>
28 #include <linux/err.h>
29 #include <linux/list.h>
30 #include <linux/errno.h>
31 #include <linux/mutex.h>
32 #include <linux/slab.h>
33 #include <linux/compat.h>
34 #include <linux/of.h>
35 #include <linux/of_device.h>
36
37 #include <linux/spi/spi.h>
38 #include <linux/spi/spidev.h>
39
40 #include <linux/uaccess.h>
41
42
43 /*
44 * This supports access to SPI devices using normal userspace I/O calls.
45 * Note that while traditional UNIX/POSIX I/O semantics are half duplex,
46 * and often mask message boundaries, full SPI support requires full duplex
47 * transfers. There are several kinds of internal message boundaries to
48 * handle chipselect management and other protocol options.
49 *
50 * SPI has a character major number assigned. We allocate minor numbers
51 * dynamically using a bitmask. You must use hotplug tools, such as udev
52 * (or mdev with busybox) to create and destroy the /dev/spidevB.C device
53 * nodes, since there is no fixed association of minor numbers with any
54 * particular SPI bus or device.
55 */
56 #define SPIDEV_MAJOR 153 /* assigned */
57 #define N_SPI_MINORS 32 /* ... up to 256 */
58
59 static DECLARE_BITMAP(minors, N_SPI_MINORS);
60
61
62 /* Bit masks for spi_device.mode management. Note that incorrect
63 * settings for some settings can cause *lots* of trouble for other
64 * devices on a shared bus:
65 *
66 * - CS_HIGH ... this device will be active when it shouldn't be
67 * - 3WIRE ... when active, it won't behave as it should
68 * - NO_CS ... there will be no explicit message boundaries; this
69 * is completely incompatible with the shared bus model
70 * - READY ... transfers may proceed when they shouldn't.
71 *
72 * REVISIT should changing those flags be privileged?
73 */
74 #define SPI_MODE_MASK (SPI_CPHA | SPI_CPOL | SPI_CS_HIGH \
75 | SPI_LSB_FIRST | SPI_3WIRE | SPI_LOOP \
76 | SPI_NO_CS | SPI_READY | SPI_TX_DUAL \
77 | SPI_TX_QUAD | SPI_RX_DUAL | SPI_RX_QUAD)
78
79 struct spidev_data {
80 dev_t devt;
81 spinlock_t spi_lock;
82 struct spi_device *spi;
83 struct list_head device_entry;
84
85 /* TX/RX buffers are NULL unless this device is open (users > 0) */
86 struct mutex buf_lock;
87 unsigned users;
88 u8 *tx_buffer;
89 u8 *rx_buffer;
90 };
91
92 static LIST_HEAD(device_list);
93 static DEFINE_MUTEX(device_list_lock);
94
95 static unsigned bufsiz = 4096;
96 module_param(bufsiz, uint, S_IRUGO);
97 MODULE_PARM_DESC(bufsiz, "data bytes in biggest supported SPI message");
98
99 /*-------------------------------------------------------------------------*/
100
101 /*
102 * We can't use the standard synchronous wrappers for file I/O; we
103 * need to protect against async removal of the underlying spi_device.
104 */
spidev_complete(void * arg)105 static void spidev_complete(void *arg)
106 {
107 complete(arg);
108 }
109
110 static ssize_t
spidev_sync(struct spidev_data * spidev,struct spi_message * message)111 spidev_sync(struct spidev_data *spidev, struct spi_message *message)
112 {
113 DECLARE_COMPLETION_ONSTACK(done);
114 int status;
115
116 message->complete = spidev_complete;
117 message->context = &done;
118
119 spin_lock_irq(&spidev->spi_lock);
120 if (spidev->spi == NULL)
121 status = -ESHUTDOWN;
122 else
123 status = spi_async(spidev->spi, message);
124 spin_unlock_irq(&spidev->spi_lock);
125
126 if (status == 0) {
127 wait_for_completion(&done);
128 status = message->status;
129 if (status == 0)
130 status = message->actual_length;
131 }
132 return status;
133 }
134
135 static inline ssize_t
spidev_sync_write(struct spidev_data * spidev,size_t len)136 spidev_sync_write(struct spidev_data *spidev, size_t len)
137 {
138 struct spi_transfer t = {
139 .tx_buf = spidev->tx_buffer,
140 .len = len,
141 };
142 struct spi_message m;
143
144 spi_message_init(&m);
145 spi_message_add_tail(&t, &m);
146 return spidev_sync(spidev, &m);
147 }
148
149 static inline ssize_t
spidev_sync_read(struct spidev_data * spidev,size_t len)150 spidev_sync_read(struct spidev_data *spidev, size_t len)
151 {
152 struct spi_transfer t = {
153 .rx_buf = spidev->rx_buffer,
154 .len = len,
155 };
156 struct spi_message m;
157
158 spi_message_init(&m);
159 spi_message_add_tail(&t, &m);
160 return spidev_sync(spidev, &m);
161 }
162
163 /*-------------------------------------------------------------------------*/
164
165 /* Read-only message with current device setup */
166 static ssize_t
spidev_read(struct file * filp,char __user * buf,size_t count,loff_t * f_pos)167 spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
168 {
169 struct spidev_data *spidev;
170 ssize_t status = 0;
171
172 /* chipselect only toggles at start or end of operation */
173 if (count > bufsiz)
174 return -EMSGSIZE;
175
176 spidev = filp->private_data;
177
178 mutex_lock(&spidev->buf_lock);
179 status = spidev_sync_read(spidev, count);
180 if (status > 0) {
181 unsigned long missing;
182
183 missing = copy_to_user(buf, spidev->rx_buffer, status);
184 if (missing == status)
185 status = -EFAULT;
186 else
187 status = status - missing;
188 }
189 mutex_unlock(&spidev->buf_lock);
190
191 return status;
192 }
193
194 /* Write-only message with current device setup */
195 static ssize_t
spidev_write(struct file * filp,const char __user * buf,size_t count,loff_t * f_pos)196 spidev_write(struct file *filp, const char __user *buf,
197 size_t count, loff_t *f_pos)
198 {
199 struct spidev_data *spidev;
200 ssize_t status = 0;
201 unsigned long missing;
202
203 /* chipselect only toggles at start or end of operation */
204 if (count > bufsiz)
205 return -EMSGSIZE;
206
207 spidev = filp->private_data;
208
209 mutex_lock(&spidev->buf_lock);
210 missing = copy_from_user(spidev->tx_buffer, buf, count);
211 if (missing == 0)
212 status = spidev_sync_write(spidev, count);
213 else
214 status = -EFAULT;
215 mutex_unlock(&spidev->buf_lock);
216
217 return status;
218 }
219
spidev_message(struct spidev_data * spidev,struct spi_ioc_transfer * u_xfers,unsigned n_xfers)220 static int spidev_message(struct spidev_data *spidev,
221 struct spi_ioc_transfer *u_xfers, unsigned n_xfers)
222 {
223 struct spi_message msg;
224 struct spi_transfer *k_xfers;
225 struct spi_transfer *k_tmp;
226 struct spi_ioc_transfer *u_tmp;
227 unsigned n, total;
228 u8 *tx_buf, *rx_buf;
229 int status = -EFAULT;
230
231 spi_message_init(&msg);
232 k_xfers = kcalloc(n_xfers, sizeof(*k_tmp), GFP_KERNEL);
233 if (k_xfers == NULL)
234 return -ENOMEM;
235
236 /* Construct spi_message, copying any tx data to bounce buffer.
237 * We walk the array of user-provided transfers, using each one
238 * to initialize a kernel version of the same transfer.
239 */
240 tx_buf = spidev->tx_buffer;
241 rx_buf = spidev->rx_buffer;
242 total = 0;
243 for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers;
244 n;
245 n--, k_tmp++, u_tmp++) {
246 k_tmp->len = u_tmp->len;
247
248 total += k_tmp->len;
249 /* Check total length of transfers. Also check each
250 * transfer length to avoid arithmetic overflow.
251 */
252 if (total > bufsiz || k_tmp->len > bufsiz) {
253 status = -EMSGSIZE;
254 goto done;
255 }
256
257 if (u_tmp->rx_buf) {
258 k_tmp->rx_buf = rx_buf;
259 if (!access_ok(VERIFY_WRITE, (u8 __user *)
260 (uintptr_t) u_tmp->rx_buf,
261 u_tmp->len))
262 goto done;
263 }
264 if (u_tmp->tx_buf) {
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 }
271 tx_buf += k_tmp->len;
272 rx_buf += k_tmp->len;
273
274 k_tmp->cs_change = !!u_tmp->cs_change;
275 k_tmp->tx_nbits = u_tmp->tx_nbits;
276 k_tmp->rx_nbits = u_tmp->rx_nbits;
277 k_tmp->bits_per_word = u_tmp->bits_per_word;
278 k_tmp->delay_usecs = u_tmp->delay_usecs;
279 k_tmp->speed_hz = u_tmp->speed_hz;
280 #ifdef VERBOSE
281 dev_dbg(&spidev->spi->dev,
282 " xfer len %zd %s%s%s%dbits %u usec %uHz\n",
283 u_tmp->len,
284 u_tmp->rx_buf ? "rx " : "",
285 u_tmp->tx_buf ? "tx " : "",
286 u_tmp->cs_change ? "cs " : "",
287 u_tmp->bits_per_word ? : spidev->spi->bits_per_word,
288 u_tmp->delay_usecs,
289 u_tmp->speed_hz ? : spidev->spi->max_speed_hz);
290 #endif
291 spi_message_add_tail(k_tmp, &msg);
292 }
293
294 status = spidev_sync(spidev, &msg);
295 if (status < 0)
296 goto done;
297
298 /* copy any rx data out of bounce buffer */
299 rx_buf = spidev->rx_buffer;
300 for (n = n_xfers, u_tmp = u_xfers; n; n--, u_tmp++) {
301 if (u_tmp->rx_buf) {
302 if (__copy_to_user((u8 __user *)
303 (uintptr_t) u_tmp->rx_buf, rx_buf,
304 u_tmp->len)) {
305 status = -EFAULT;
306 goto done;
307 }
308 }
309 rx_buf += u_tmp->len;
310 }
311 status = total;
312
313 done:
314 kfree(k_xfers);
315 return status;
316 }
317
318 static long
spidev_ioctl(struct file * filp,unsigned int cmd,unsigned long arg)319 spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
320 {
321 int err = 0;
322 int retval = 0;
323 struct spidev_data *spidev;
324 struct spi_device *spi;
325 u32 tmp;
326 unsigned n_ioc;
327 struct spi_ioc_transfer *ioc;
328
329 /* Check type and command number */
330 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC)
331 return -ENOTTY;
332
333 /* Check access direction once here; don't repeat below.
334 * IOC_DIR is from the user perspective, while access_ok is
335 * from the kernel perspective; so they look reversed.
336 */
337 if (_IOC_DIR(cmd) & _IOC_READ)
338 err = !access_ok(VERIFY_WRITE,
339 (void __user *)arg, _IOC_SIZE(cmd));
340 if (err == 0 && _IOC_DIR(cmd) & _IOC_WRITE)
341 err = !access_ok(VERIFY_READ,
342 (void __user *)arg, _IOC_SIZE(cmd));
343 if (err)
344 return -EFAULT;
345
346 /* guard against device removal before, or while,
347 * we issue this ioctl.
348 */
349 spidev = filp->private_data;
350 spin_lock_irq(&spidev->spi_lock);
351 spi = spi_dev_get(spidev->spi);
352 spin_unlock_irq(&spidev->spi_lock);
353
354 if (spi == NULL)
355 return -ESHUTDOWN;
356
357 /* use the buffer lock here for triple duty:
358 * - prevent I/O (from us) so calling spi_setup() is safe;
359 * - prevent concurrent SPI_IOC_WR_* from morphing
360 * data fields while SPI_IOC_RD_* reads them;
361 * - SPI_IOC_MESSAGE needs the buffer locked "normally".
362 */
363 mutex_lock(&spidev->buf_lock);
364
365 switch (cmd) {
366 /* read requests */
367 case SPI_IOC_RD_MODE:
368 retval = __put_user(spi->mode & SPI_MODE_MASK,
369 (__u8 __user *)arg);
370 break;
371 case SPI_IOC_RD_MODE32:
372 retval = __put_user(spi->mode & SPI_MODE_MASK,
373 (__u32 __user *)arg);
374 break;
375 case SPI_IOC_RD_LSB_FIRST:
376 retval = __put_user((spi->mode & SPI_LSB_FIRST) ? 1 : 0,
377 (__u8 __user *)arg);
378 break;
379 case SPI_IOC_RD_BITS_PER_WORD:
380 retval = __put_user(spi->bits_per_word, (__u8 __user *)arg);
381 break;
382 case SPI_IOC_RD_MAX_SPEED_HZ:
383 retval = __put_user(spi->max_speed_hz, (__u32 __user *)arg);
384 break;
385
386 /* write requests */
387 case SPI_IOC_WR_MODE:
388 case SPI_IOC_WR_MODE32:
389 if (cmd == SPI_IOC_WR_MODE)
390 retval = __get_user(tmp, (u8 __user *)arg);
391 else
392 retval = __get_user(tmp, (u32 __user *)arg);
393 if (retval == 0) {
394 u32 save = spi->mode;
395
396 if (tmp & ~SPI_MODE_MASK) {
397 retval = -EINVAL;
398 break;
399 }
400
401 tmp |= spi->mode & ~SPI_MODE_MASK;
402 spi->mode = (u16)tmp;
403 retval = spi_setup(spi);
404 if (retval < 0)
405 spi->mode = save;
406 else
407 dev_dbg(&spi->dev, "spi mode %x\n", tmp);
408 }
409 break;
410 case SPI_IOC_WR_LSB_FIRST:
411 retval = __get_user(tmp, (__u8 __user *)arg);
412 if (retval == 0) {
413 u32 save = spi->mode;
414
415 if (tmp)
416 spi->mode |= SPI_LSB_FIRST;
417 else
418 spi->mode &= ~SPI_LSB_FIRST;
419 retval = spi_setup(spi);
420 if (retval < 0)
421 spi->mode = save;
422 else
423 dev_dbg(&spi->dev, "%csb first\n",
424 tmp ? 'l' : 'm');
425 }
426 break;
427 case SPI_IOC_WR_BITS_PER_WORD:
428 retval = __get_user(tmp, (__u8 __user *)arg);
429 if (retval == 0) {
430 u8 save = spi->bits_per_word;
431
432 spi->bits_per_word = tmp;
433 retval = spi_setup(spi);
434 if (retval < 0)
435 spi->bits_per_word = save;
436 else
437 dev_dbg(&spi->dev, "%d bits per word\n", tmp);
438 }
439 break;
440 case SPI_IOC_WR_MAX_SPEED_HZ:
441 retval = __get_user(tmp, (__u32 __user *)arg);
442 if (retval == 0) {
443 u32 save = spi->max_speed_hz;
444
445 spi->max_speed_hz = tmp;
446 retval = spi_setup(spi);
447 if (retval < 0)
448 spi->max_speed_hz = save;
449 else
450 dev_dbg(&spi->dev, "%d Hz (max)\n", tmp);
451 }
452 break;
453
454 default:
455 /* segmented and/or full-duplex I/O request */
456 if (_IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0))
457 || _IOC_DIR(cmd) != _IOC_WRITE) {
458 retval = -ENOTTY;
459 break;
460 }
461
462 tmp = _IOC_SIZE(cmd);
463 if ((tmp % sizeof(struct spi_ioc_transfer)) != 0) {
464 retval = -EINVAL;
465 break;
466 }
467 n_ioc = tmp / sizeof(struct spi_ioc_transfer);
468 if (n_ioc == 0)
469 break;
470
471 /* copy into scratch area */
472 ioc = kmalloc(tmp, GFP_KERNEL);
473 if (!ioc) {
474 retval = -ENOMEM;
475 break;
476 }
477 if (__copy_from_user(ioc, (void __user *)arg, tmp)) {
478 kfree(ioc);
479 retval = -EFAULT;
480 break;
481 }
482
483 /* translate to spi_message, execute */
484 retval = spidev_message(spidev, ioc, n_ioc);
485 kfree(ioc);
486 break;
487 }
488
489 mutex_unlock(&spidev->buf_lock);
490 spi_dev_put(spi);
491 return retval;
492 }
493
494 #ifdef CONFIG_COMPAT
495 static long
spidev_compat_ioctl(struct file * filp,unsigned int cmd,unsigned long arg)496 spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
497 {
498 return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
499 }
500 #else
501 #define spidev_compat_ioctl NULL
502 #endif /* CONFIG_COMPAT */
503
spidev_open(struct inode * inode,struct file * filp)504 static int spidev_open(struct inode *inode, struct file *filp)
505 {
506 struct spidev_data *spidev;
507 int status = -ENXIO;
508
509 mutex_lock(&device_list_lock);
510
511 list_for_each_entry(spidev, &device_list, device_entry) {
512 if (spidev->devt == inode->i_rdev) {
513 status = 0;
514 break;
515 }
516 }
517
518 if (status) {
519 pr_debug("spidev: nothing for minor %d\n", iminor(inode));
520 goto err_find_dev;
521 }
522
523 if (!spidev->tx_buffer) {
524 spidev->tx_buffer = kmalloc(bufsiz, GFP_KERNEL);
525 if (!spidev->tx_buffer) {
526 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
527 status = -ENOMEM;
528 goto err_find_dev;
529 }
530 }
531
532 if (!spidev->rx_buffer) {
533 spidev->rx_buffer = kmalloc(bufsiz, GFP_KERNEL);
534 if (!spidev->rx_buffer) {
535 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
536 status = -ENOMEM;
537 goto err_alloc_rx_buf;
538 }
539 }
540
541 spidev->users++;
542 filp->private_data = spidev;
543 nonseekable_open(inode, filp);
544
545 mutex_unlock(&device_list_lock);
546 return 0;
547
548 err_alloc_rx_buf:
549 kfree(spidev->tx_buffer);
550 spidev->tx_buffer = NULL;
551 err_find_dev:
552 mutex_unlock(&device_list_lock);
553 return status;
554 }
555
spidev_release(struct inode * inode,struct file * filp)556 static int spidev_release(struct inode *inode, struct file *filp)
557 {
558 struct spidev_data *spidev;
559 int status = 0;
560
561 mutex_lock(&device_list_lock);
562 spidev = filp->private_data;
563 filp->private_data = NULL;
564
565 /* last close? */
566 spidev->users--;
567 if (!spidev->users) {
568 int dofree;
569
570 kfree(spidev->tx_buffer);
571 spidev->tx_buffer = NULL;
572
573 kfree(spidev->rx_buffer);
574 spidev->rx_buffer = NULL;
575
576 /* ... after we unbound from the underlying device? */
577 spin_lock_irq(&spidev->spi_lock);
578 dofree = (spidev->spi == NULL);
579 spin_unlock_irq(&spidev->spi_lock);
580
581 if (dofree)
582 kfree(spidev);
583 }
584 mutex_unlock(&device_list_lock);
585
586 return status;
587 }
588
589 static const struct file_operations spidev_fops = {
590 .owner = THIS_MODULE,
591 /* REVISIT switch to aio primitives, so that userspace
592 * gets more complete API coverage. It'll simplify things
593 * too, except for the locking.
594 */
595 .write = spidev_write,
596 .read = spidev_read,
597 .unlocked_ioctl = spidev_ioctl,
598 .compat_ioctl = spidev_compat_ioctl,
599 .open = spidev_open,
600 .release = spidev_release,
601 .llseek = no_llseek,
602 };
603
604 /*-------------------------------------------------------------------------*/
605
606 /* The main reason to have this class is to make mdev/udev create the
607 * /dev/spidevB.C character device nodes exposing our userspace API.
608 * It also simplifies memory management.
609 */
610
611 static struct class *spidev_class;
612
613 /*-------------------------------------------------------------------------*/
614
spidev_probe(struct spi_device * spi)615 static int spidev_probe(struct spi_device *spi)
616 {
617 struct spidev_data *spidev;
618 int status;
619 unsigned long minor;
620
621 /* Allocate driver data */
622 spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);
623 if (!spidev)
624 return -ENOMEM;
625
626 /* Initialize the driver data */
627 spidev->spi = spi;
628 spin_lock_init(&spidev->spi_lock);
629 mutex_init(&spidev->buf_lock);
630
631 INIT_LIST_HEAD(&spidev->device_entry);
632
633 /* If we can allocate a minor number, hook up this device.
634 * Reusing minors is fine so long as udev or mdev is working.
635 */
636 mutex_lock(&device_list_lock);
637 minor = find_first_zero_bit(minors, N_SPI_MINORS);
638 if (minor < N_SPI_MINORS) {
639 struct device *dev;
640
641 spidev->devt = MKDEV(SPIDEV_MAJOR, minor);
642 dev = device_create(spidev_class, &spi->dev, spidev->devt,
643 spidev, "spidev%d.%d",
644 spi->master->bus_num, spi->chip_select);
645 status = PTR_ERR_OR_ZERO(dev);
646 } else {
647 dev_dbg(&spi->dev, "no minor number available!\n");
648 status = -ENODEV;
649 }
650 if (status == 0) {
651 set_bit(minor, minors);
652 list_add(&spidev->device_entry, &device_list);
653 }
654 mutex_unlock(&device_list_lock);
655
656 if (status == 0)
657 spi_set_drvdata(spi, spidev);
658 else
659 kfree(spidev);
660
661 return status;
662 }
663
spidev_remove(struct spi_device * spi)664 static int spidev_remove(struct spi_device *spi)
665 {
666 struct spidev_data *spidev = spi_get_drvdata(spi);
667
668 /* make sure ops on existing fds can abort cleanly */
669 spin_lock_irq(&spidev->spi_lock);
670 spidev->spi = NULL;
671 spin_unlock_irq(&spidev->spi_lock);
672
673 /* prevent new opens */
674 mutex_lock(&device_list_lock);
675 list_del(&spidev->device_entry);
676 device_destroy(spidev_class, spidev->devt);
677 clear_bit(MINOR(spidev->devt), minors);
678 if (spidev->users == 0)
679 kfree(spidev);
680 mutex_unlock(&device_list_lock);
681
682 return 0;
683 }
684
685 static const struct of_device_id spidev_dt_ids[] = {
686 { .compatible = "rohm,dh2228fv" },
687 {},
688 };
689
690 MODULE_DEVICE_TABLE(of, spidev_dt_ids);
691
692 static struct spi_driver spidev_spi_driver = {
693 .driver = {
694 .name = "spidev",
695 .owner = THIS_MODULE,
696 .of_match_table = of_match_ptr(spidev_dt_ids),
697 },
698 .probe = spidev_probe,
699 .remove = spidev_remove,
700
701 /* NOTE: suspend/resume methods are not necessary here.
702 * We don't do anything except pass the requests to/from
703 * the underlying controller. The refrigerator handles
704 * most issues; the controller driver handles the rest.
705 */
706 };
707
708 /*-------------------------------------------------------------------------*/
709
spidev_init(void)710 static int __init spidev_init(void)
711 {
712 int status;
713
714 /* Claim our 256 reserved device numbers. Then register a class
715 * that will key udev/mdev to add/remove /dev nodes. Last, register
716 * the driver which manages those device numbers.
717 */
718 BUILD_BUG_ON(N_SPI_MINORS > 256);
719 status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);
720 if (status < 0)
721 return status;
722
723 spidev_class = class_create(THIS_MODULE, "spidev");
724 if (IS_ERR(spidev_class)) {
725 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
726 return PTR_ERR(spidev_class);
727 }
728
729 status = spi_register_driver(&spidev_spi_driver);
730 if (status < 0) {
731 class_destroy(spidev_class);
732 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
733 }
734 return status;
735 }
736 module_init(spidev_init);
737
spidev_exit(void)738 static void __exit spidev_exit(void)
739 {
740 spi_unregister_driver(&spidev_spi_driver);
741 class_destroy(spidev_class);
742 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
743 }
744 module_exit(spidev_exit);
745
746 MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>");
747 MODULE_DESCRIPTION("User mode SPI device interface");
748 MODULE_LICENSE("GPL");
749 MODULE_ALIAS("spi:spidev");
750