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Using BUG_ON() as an assert() is _never_ acceptable
[deliverable/linux.git] / drivers / spi / spidev.c
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 DECLARE_COMPLETION_ONSTACK(done);
103 int status;
104 struct spi_device *spi;
105
106 spin_lock_irq(&spidev->spi_lock);
107 spi = spidev->spi;
108 spin_unlock_irq(&spidev->spi_lock);
109
110 if (spi == NULL)
111 status = -ESHUTDOWN;
112 else
113 status = spi_sync(spi, message);
114
115 if (status == 0)
116 status = message->actual_length;
117
118 return status;
119 }
120
121 static inline ssize_t
122 spidev_sync_write(struct spidev_data *spidev, size_t len)
123 {
124 struct spi_transfer t = {
125 .tx_buf = spidev->tx_buffer,
126 .len = len,
127 .speed_hz = spidev->speed_hz,
128 };
129 struct spi_message m;
130
131 spi_message_init(&m);
132 spi_message_add_tail(&t, &m);
133 return spidev_sync(spidev, &m);
134 }
135
136 static inline ssize_t
137 spidev_sync_read(struct spidev_data *spidev, size_t len)
138 {
139 struct spi_transfer t = {
140 .rx_buf = spidev->rx_buffer,
141 .len = len,
142 .speed_hz = spidev->speed_hz,
143 };
144 struct spi_message m;
145
146 spi_message_init(&m);
147 spi_message_add_tail(&t, &m);
148 return spidev_sync(spidev, &m);
149 }
150
151 /*-------------------------------------------------------------------------*/
152
153 /* Read-only message with current device setup */
154 static ssize_t
155 spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
156 {
157 struct spidev_data *spidev;
158 ssize_t status = 0;
159
160 /* chipselect only toggles at start or end of operation */
161 if (count > bufsiz)
162 return -EMSGSIZE;
163
164 spidev = filp->private_data;
165
166 mutex_lock(&spidev->buf_lock);
167 status = spidev_sync_read(spidev, count);
168 if (status > 0) {
169 unsigned long missing;
170
171 missing = copy_to_user(buf, spidev->rx_buffer, status);
172 if (missing == status)
173 status = -EFAULT;
174 else
175 status = status - missing;
176 }
177 mutex_unlock(&spidev->buf_lock);
178
179 return status;
180 }
181
182 /* Write-only message with current device setup */
183 static ssize_t
184 spidev_write(struct file *filp, const char __user *buf,
185 size_t count, loff_t *f_pos)
186 {
187 struct spidev_data *spidev;
188 ssize_t status = 0;
189 unsigned long missing;
190
191 /* chipselect only toggles at start or end of operation */
192 if (count > bufsiz)
193 return -EMSGSIZE;
194
195 spidev = filp->private_data;
196
197 mutex_lock(&spidev->buf_lock);
198 missing = copy_from_user(spidev->tx_buffer, buf, count);
199 if (missing == 0)
200 status = spidev_sync_write(spidev, count);
201 else
202 status = -EFAULT;
203 mutex_unlock(&spidev->buf_lock);
204
205 return status;
206 }
207
208 static int spidev_message(struct spidev_data *spidev,
209 struct spi_ioc_transfer *u_xfers, unsigned n_xfers)
210 {
211 struct spi_message msg;
212 struct spi_transfer *k_xfers;
213 struct spi_transfer *k_tmp;
214 struct spi_ioc_transfer *u_tmp;
215 unsigned n, total, tx_total, rx_total;
216 u8 *tx_buf, *rx_buf;
217 int status = -EFAULT;
218
219 spi_message_init(&msg);
220 k_xfers = kcalloc(n_xfers, sizeof(*k_tmp), GFP_KERNEL);
221 if (k_xfers == NULL)
222 return -ENOMEM;
223
224 /* Construct spi_message, copying any tx data to bounce buffer.
225 * We walk the array of user-provided transfers, using each one
226 * to initialize a kernel version of the same transfer.
227 */
228 tx_buf = spidev->tx_buffer;
229 rx_buf = spidev->rx_buffer;
230 total = 0;
231 tx_total = 0;
232 rx_total = 0;
233 for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers;
234 n;
235 n--, k_tmp++, u_tmp++) {
236 k_tmp->len = u_tmp->len;
237
238 total += k_tmp->len;
239 /* Since the function returns the total length of transfers
240 * on success, restrict the total to positive int values to
241 * avoid the return value looking like an error. Also check
242 * each transfer length to avoid arithmetic overflow.
243 */
244 if (total > INT_MAX || k_tmp->len > INT_MAX) {
245 status = -EMSGSIZE;
246 goto done;
247 }
248
249 if (u_tmp->rx_buf) {
250 /* this transfer needs space in RX bounce buffer */
251 rx_total += k_tmp->len;
252 if (rx_total > bufsiz) {
253 status = -EMSGSIZE;
254 goto done;
255 }
256 k_tmp->rx_buf = rx_buf;
257 if (!access_ok(VERIFY_WRITE, (u8 __user *)
258 (uintptr_t) u_tmp->rx_buf,
259 u_tmp->len))
260 goto done;
261 rx_buf += k_tmp->len;
262 }
263 if (u_tmp->tx_buf) {
264 /* this transfer needs space in TX bounce buffer */
265 tx_total += k_tmp->len;
266 if (tx_total > bufsiz) {
267 status = -EMSGSIZE;
268 goto done;
269 }
270 k_tmp->tx_buf = tx_buf;
271 if (copy_from_user(tx_buf, (const u8 __user *)
272 (uintptr_t) u_tmp->tx_buf,
273 u_tmp->len))
274 goto done;
275 tx_buf += k_tmp->len;
276 }
277
278 k_tmp->cs_change = !!u_tmp->cs_change;
279 k_tmp->tx_nbits = u_tmp->tx_nbits;
280 k_tmp->rx_nbits = u_tmp->rx_nbits;
281 k_tmp->bits_per_word = u_tmp->bits_per_word;
282 k_tmp->delay_usecs = u_tmp->delay_usecs;
283 k_tmp->speed_hz = u_tmp->speed_hz;
284 if (!k_tmp->speed_hz)
285 k_tmp->speed_hz = spidev->speed_hz;
286 #ifdef VERBOSE
287 dev_dbg(&spidev->spi->dev,
288 " xfer len %u %s%s%s%dbits %u usec %uHz\n",
289 u_tmp->len,
290 u_tmp->rx_buf ? "rx " : "",
291 u_tmp->tx_buf ? "tx " : "",
292 u_tmp->cs_change ? "cs " : "",
293 u_tmp->bits_per_word ? : spidev->spi->bits_per_word,
294 u_tmp->delay_usecs,
295 u_tmp->speed_hz ? : spidev->spi->max_speed_hz);
296 #endif
297 spi_message_add_tail(k_tmp, &msg);
298 }
299
300 status = spidev_sync(spidev, &msg);
301 if (status < 0)
302 goto done;
303
304 /* copy any rx data out of bounce buffer */
305 rx_buf = spidev->rx_buffer;
306 for (n = n_xfers, u_tmp = u_xfers; n; n--, u_tmp++) {
307 if (u_tmp->rx_buf) {
308 if (__copy_to_user((u8 __user *)
309 (uintptr_t) u_tmp->rx_buf, rx_buf,
310 u_tmp->len)) {
311 status = -EFAULT;
312 goto done;
313 }
314 rx_buf += u_tmp->len;
315 }
316 }
317 status = total;
318
319 done:
320 kfree(k_xfers);
321 return status;
322 }
323
324 static struct spi_ioc_transfer *
325 spidev_get_ioc_message(unsigned int cmd, struct spi_ioc_transfer __user *u_ioc,
326 unsigned *n_ioc)
327 {
328 struct spi_ioc_transfer *ioc;
329 u32 tmp;
330
331 /* Check type, command number and direction */
332 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC
333 || _IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0))
334 || _IOC_DIR(cmd) != _IOC_WRITE)
335 return ERR_PTR(-ENOTTY);
336
337 tmp = _IOC_SIZE(cmd);
338 if ((tmp % sizeof(struct spi_ioc_transfer)) != 0)
339 return ERR_PTR(-EINVAL);
340 *n_ioc = tmp / sizeof(struct spi_ioc_transfer);
341 if (*n_ioc == 0)
342 return NULL;
343
344 /* copy into scratch area */
345 ioc = kmalloc(tmp, GFP_KERNEL);
346 if (!ioc)
347 return ERR_PTR(-ENOMEM);
348 if (__copy_from_user(ioc, u_ioc, tmp)) {
349 kfree(ioc);
350 return ERR_PTR(-EFAULT);
351 }
352 return ioc;
353 }
354
355 static long
356 spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
357 {
358 int err = 0;
359 int retval = 0;
360 struct spidev_data *spidev;
361 struct spi_device *spi;
362 u32 tmp;
363 unsigned n_ioc;
364 struct spi_ioc_transfer *ioc;
365
366 /* Check type and command number */
367 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC)
368 return -ENOTTY;
369
370 /* Check access direction once here; don't repeat below.
371 * IOC_DIR is from the user perspective, while access_ok is
372 * from the kernel perspective; so they look reversed.
373 */
374 if (_IOC_DIR(cmd) & _IOC_READ)
375 err = !access_ok(VERIFY_WRITE,
376 (void __user *)arg, _IOC_SIZE(cmd));
377 if (err == 0 && _IOC_DIR(cmd) & _IOC_WRITE)
378 err = !access_ok(VERIFY_READ,
379 (void __user *)arg, _IOC_SIZE(cmd));
380 if (err)
381 return -EFAULT;
382
383 /* guard against device removal before, or while,
384 * we issue this ioctl.
385 */
386 spidev = filp->private_data;
387 spin_lock_irq(&spidev->spi_lock);
388 spi = spi_dev_get(spidev->spi);
389 spin_unlock_irq(&spidev->spi_lock);
390
391 if (spi == NULL)
392 return -ESHUTDOWN;
393
394 /* use the buffer lock here for triple duty:
395 * - prevent I/O (from us) so calling spi_setup() is safe;
396 * - prevent concurrent SPI_IOC_WR_* from morphing
397 * data fields while SPI_IOC_RD_* reads them;
398 * - SPI_IOC_MESSAGE needs the buffer locked "normally".
399 */
400 mutex_lock(&spidev->buf_lock);
401
402 switch (cmd) {
403 /* read requests */
404 case SPI_IOC_RD_MODE:
405 retval = __put_user(spi->mode & SPI_MODE_MASK,
406 (__u8 __user *)arg);
407 break;
408 case SPI_IOC_RD_MODE32:
409 retval = __put_user(spi->mode & SPI_MODE_MASK,
410 (__u32 __user *)arg);
411 break;
412 case SPI_IOC_RD_LSB_FIRST:
413 retval = __put_user((spi->mode & SPI_LSB_FIRST) ? 1 : 0,
414 (__u8 __user *)arg);
415 break;
416 case SPI_IOC_RD_BITS_PER_WORD:
417 retval = __put_user(spi->bits_per_word, (__u8 __user *)arg);
418 break;
419 case SPI_IOC_RD_MAX_SPEED_HZ:
420 retval = __put_user(spidev->speed_hz, (__u32 __user *)arg);
421 break;
422
423 /* write requests */
424 case SPI_IOC_WR_MODE:
425 case SPI_IOC_WR_MODE32:
426 if (cmd == SPI_IOC_WR_MODE)
427 retval = __get_user(tmp, (u8 __user *)arg);
428 else
429 retval = __get_user(tmp, (u32 __user *)arg);
430 if (retval == 0) {
431 u32 save = spi->mode;
432
433 if (tmp & ~SPI_MODE_MASK) {
434 retval = -EINVAL;
435 break;
436 }
437
438 tmp |= spi->mode & ~SPI_MODE_MASK;
439 spi->mode = (u16)tmp;
440 retval = spi_setup(spi);
441 if (retval < 0)
442 spi->mode = save;
443 else
444 dev_dbg(&spi->dev, "spi mode %x\n", tmp);
445 }
446 break;
447 case SPI_IOC_WR_LSB_FIRST:
448 retval = __get_user(tmp, (__u8 __user *)arg);
449 if (retval == 0) {
450 u32 save = spi->mode;
451
452 if (tmp)
453 spi->mode |= SPI_LSB_FIRST;
454 else
455 spi->mode &= ~SPI_LSB_FIRST;
456 retval = spi_setup(spi);
457 if (retval < 0)
458 spi->mode = save;
459 else
460 dev_dbg(&spi->dev, "%csb first\n",
461 tmp ? 'l' : 'm');
462 }
463 break;
464 case SPI_IOC_WR_BITS_PER_WORD:
465 retval = __get_user(tmp, (__u8 __user *)arg);
466 if (retval == 0) {
467 u8 save = spi->bits_per_word;
468
469 spi->bits_per_word = tmp;
470 retval = spi_setup(spi);
471 if (retval < 0)
472 spi->bits_per_word = save;
473 else
474 dev_dbg(&spi->dev, "%d bits per word\n", tmp);
475 }
476 break;
477 case SPI_IOC_WR_MAX_SPEED_HZ:
478 retval = __get_user(tmp, (__u32 __user *)arg);
479 if (retval == 0) {
480 u32 save = spi->max_speed_hz;
481
482 spi->max_speed_hz = tmp;
483 retval = spi_setup(spi);
484 if (retval >= 0)
485 spidev->speed_hz = tmp;
486 else
487 dev_dbg(&spi->dev, "%d Hz (max)\n", tmp);
488 spi->max_speed_hz = save;
489 }
490 break;
491
492 default:
493 /* segmented and/or full-duplex I/O request */
494 /* Check message and copy into scratch area */
495 ioc = spidev_get_ioc_message(cmd,
496 (struct spi_ioc_transfer __user *)arg, &n_ioc);
497 if (IS_ERR(ioc)) {
498 retval = PTR_ERR(ioc);
499 break;
500 }
501 if (!ioc)
502 break; /* n_ioc is also 0 */
503
504 /* translate to spi_message, execute */
505 retval = spidev_message(spidev, ioc, n_ioc);
506 kfree(ioc);
507 break;
508 }
509
510 mutex_unlock(&spidev->buf_lock);
511 spi_dev_put(spi);
512 return retval;
513 }
514
515 #ifdef CONFIG_COMPAT
516 static long
517 spidev_compat_ioc_message(struct file *filp, unsigned int cmd,
518 unsigned long arg)
519 {
520 struct spi_ioc_transfer __user *u_ioc;
521 int retval = 0;
522 struct spidev_data *spidev;
523 struct spi_device *spi;
524 unsigned n_ioc, n;
525 struct spi_ioc_transfer *ioc;
526
527 u_ioc = (struct spi_ioc_transfer __user *) compat_ptr(arg);
528 if (!access_ok(VERIFY_READ, u_ioc, _IOC_SIZE(cmd)))
529 return -EFAULT;
530
531 /* guard against device removal before, or while,
532 * we issue this ioctl.
533 */
534 spidev = filp->private_data;
535 spin_lock_irq(&spidev->spi_lock);
536 spi = spi_dev_get(spidev->spi);
537 spin_unlock_irq(&spidev->spi_lock);
538
539 if (spi == NULL)
540 return -ESHUTDOWN;
541
542 /* SPI_IOC_MESSAGE needs the buffer locked "normally" */
543 mutex_lock(&spidev->buf_lock);
544
545 /* Check message and copy into scratch area */
546 ioc = spidev_get_ioc_message(cmd, u_ioc, &n_ioc);
547 if (IS_ERR(ioc)) {
548 retval = PTR_ERR(ioc);
549 goto done;
550 }
551 if (!ioc)
552 goto done; /* n_ioc is also 0 */
553
554 /* Convert buffer pointers */
555 for (n = 0; n < n_ioc; n++) {
556 ioc[n].rx_buf = (uintptr_t) compat_ptr(ioc[n].rx_buf);
557 ioc[n].tx_buf = (uintptr_t) compat_ptr(ioc[n].tx_buf);
558 }
559
560 /* translate to spi_message, execute */
561 retval = spidev_message(spidev, ioc, n_ioc);
562 kfree(ioc);
563
564 done:
565 mutex_unlock(&spidev->buf_lock);
566 spi_dev_put(spi);
567 return retval;
568 }
569
570 static long
571 spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
572 {
573 if (_IOC_TYPE(cmd) == SPI_IOC_MAGIC
574 && _IOC_NR(cmd) == _IOC_NR(SPI_IOC_MESSAGE(0))
575 && _IOC_DIR(cmd) == _IOC_WRITE)
576 return spidev_compat_ioc_message(filp, cmd, arg);
577
578 return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
579 }
580 #else
581 #define spidev_compat_ioctl NULL
582 #endif /* CONFIG_COMPAT */
583
584 static int spidev_open(struct inode *inode, struct file *filp)
585 {
586 struct spidev_data *spidev;
587 int status = -ENXIO;
588
589 mutex_lock(&device_list_lock);
590
591 list_for_each_entry(spidev, &device_list, device_entry) {
592 if (spidev->devt == inode->i_rdev) {
593 status = 0;
594 break;
595 }
596 }
597
598 if (status) {
599 pr_debug("spidev: nothing for minor %d\n", iminor(inode));
600 goto err_find_dev;
601 }
602
603 if (!spidev->tx_buffer) {
604 spidev->tx_buffer = kmalloc(bufsiz, GFP_KERNEL);
605 if (!spidev->tx_buffer) {
606 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
607 status = -ENOMEM;
608 goto err_find_dev;
609 }
610 }
611
612 if (!spidev->rx_buffer) {
613 spidev->rx_buffer = kmalloc(bufsiz, GFP_KERNEL);
614 if (!spidev->rx_buffer) {
615 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
616 status = -ENOMEM;
617 goto err_alloc_rx_buf;
618 }
619 }
620
621 spidev->users++;
622 filp->private_data = spidev;
623 nonseekable_open(inode, filp);
624
625 mutex_unlock(&device_list_lock);
626 return 0;
627
628 err_alloc_rx_buf:
629 kfree(spidev->tx_buffer);
630 spidev->tx_buffer = NULL;
631 err_find_dev:
632 mutex_unlock(&device_list_lock);
633 return status;
634 }
635
636 static int spidev_release(struct inode *inode, struct file *filp)
637 {
638 struct spidev_data *spidev;
639
640 mutex_lock(&device_list_lock);
641 spidev = filp->private_data;
642 filp->private_data = NULL;
643
644 /* last close? */
645 spidev->users--;
646 if (!spidev->users) {
647 int dofree;
648
649 kfree(spidev->tx_buffer);
650 spidev->tx_buffer = NULL;
651
652 kfree(spidev->rx_buffer);
653 spidev->rx_buffer = NULL;
654
655 spin_lock_irq(&spidev->spi_lock);
656 if (spidev->spi)
657 spidev->speed_hz = spidev->spi->max_speed_hz;
658
659 /* ... after we unbound from the underlying device? */
660 dofree = (spidev->spi == NULL);
661 spin_unlock_irq(&spidev->spi_lock);
662
663 if (dofree)
664 kfree(spidev);
665 }
666 mutex_unlock(&device_list_lock);
667
668 return 0;
669 }
670
671 static const struct file_operations spidev_fops = {
672 .owner = THIS_MODULE,
673 /* REVISIT switch to aio primitives, so that userspace
674 * gets more complete API coverage. It'll simplify things
675 * too, except for the locking.
676 */
677 .write = spidev_write,
678 .read = spidev_read,
679 .unlocked_ioctl = spidev_ioctl,
680 .compat_ioctl = spidev_compat_ioctl,
681 .open = spidev_open,
682 .release = spidev_release,
683 .llseek = no_llseek,
684 };
685
686 /*-------------------------------------------------------------------------*/
687
688 /* The main reason to have this class is to make mdev/udev create the
689 * /dev/spidevB.C character device nodes exposing our userspace API.
690 * It also simplifies memory management.
691 */
692
693 static struct class *spidev_class;
694
695 #ifdef CONFIG_OF
696 static const struct of_device_id spidev_dt_ids[] = {
697 { .compatible = "rohm,dh2228fv" },
698 { .compatible = "lineartechnology,ltc2488" },
699 {},
700 };
701 MODULE_DEVICE_TABLE(of, spidev_dt_ids);
702 #endif
703
704 #ifdef CONFIG_ACPI
705
706 /* Dummy SPI devices not to be used in production systems */
707 #define SPIDEV_ACPI_DUMMY 1
708
709 static const struct acpi_device_id spidev_acpi_ids[] = {
710 /*
711 * The ACPI SPT000* devices are only meant for development and
712 * testing. Systems used in production should have a proper ACPI
713 * description of the connected peripheral and they should also use
714 * a proper driver instead of poking directly to the SPI bus.
715 */
716 { "SPT0001", SPIDEV_ACPI_DUMMY },
717 { "SPT0002", SPIDEV_ACPI_DUMMY },
718 { "SPT0003", SPIDEV_ACPI_DUMMY },
719 {},
720 };
721 MODULE_DEVICE_TABLE(acpi, spidev_acpi_ids);
722
723 static void spidev_probe_acpi(struct spi_device *spi)
724 {
725 const struct acpi_device_id *id;
726
727 if (!has_acpi_companion(&spi->dev))
728 return;
729
730 id = acpi_match_device(spidev_acpi_ids, &spi->dev);
731 if (WARN_ON(!id))
732 return;
733
734 if (id->driver_data == SPIDEV_ACPI_DUMMY)
735 dev_warn(&spi->dev, "do not use this driver in production systems!\n");
736 }
737 #else
738 static inline void spidev_probe_acpi(struct spi_device *spi) {}
739 #endif
740
741 /*-------------------------------------------------------------------------*/
742
743 static int spidev_probe(struct spi_device *spi)
744 {
745 struct spidev_data *spidev;
746 int status;
747 unsigned long minor;
748
749 /*
750 * spidev should never be referenced in DT without a specific
751 * compatible string, it is a Linux implementation thing
752 * rather than a description of the hardware.
753 */
754 if (spi->dev.of_node && !of_match_device(spidev_dt_ids, &spi->dev)) {
755 dev_err(&spi->dev, "buggy DT: spidev listed directly in DT\n");
756 WARN_ON(spi->dev.of_node &&
757 !of_match_device(spidev_dt_ids, &spi->dev));
758 }
759
760 spidev_probe_acpi(spi);
761
762 /* Allocate driver data */
763 spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);
764 if (!spidev)
765 return -ENOMEM;
766
767 /* Initialize the driver data */
768 spidev->spi = spi;
769 spin_lock_init(&spidev->spi_lock);
770 mutex_init(&spidev->buf_lock);
771
772 INIT_LIST_HEAD(&spidev->device_entry);
773
774 /* If we can allocate a minor number, hook up this device.
775 * Reusing minors is fine so long as udev or mdev is working.
776 */
777 mutex_lock(&device_list_lock);
778 minor = find_first_zero_bit(minors, N_SPI_MINORS);
779 if (minor < N_SPI_MINORS) {
780 struct device *dev;
781
782 spidev->devt = MKDEV(SPIDEV_MAJOR, minor);
783 dev = device_create(spidev_class, &spi->dev, spidev->devt,
784 spidev, "spidev%d.%d",
785 spi->master->bus_num, spi->chip_select);
786 status = PTR_ERR_OR_ZERO(dev);
787 } else {
788 dev_dbg(&spi->dev, "no minor number available!\n");
789 status = -ENODEV;
790 }
791 if (status == 0) {
792 set_bit(minor, minors);
793 list_add(&spidev->device_entry, &device_list);
794 }
795 mutex_unlock(&device_list_lock);
796
797 spidev->speed_hz = spi->max_speed_hz;
798
799 if (status == 0)
800 spi_set_drvdata(spi, spidev);
801 else
802 kfree(spidev);
803
804 return status;
805 }
806
807 static int spidev_remove(struct spi_device *spi)
808 {
809 struct spidev_data *spidev = spi_get_drvdata(spi);
810
811 /* make sure ops on existing fds can abort cleanly */
812 spin_lock_irq(&spidev->spi_lock);
813 spidev->spi = NULL;
814 spin_unlock_irq(&spidev->spi_lock);
815
816 /* prevent new opens */
817 mutex_lock(&device_list_lock);
818 list_del(&spidev->device_entry);
819 device_destroy(spidev_class, spidev->devt);
820 clear_bit(MINOR(spidev->devt), minors);
821 if (spidev->users == 0)
822 kfree(spidev);
823 mutex_unlock(&device_list_lock);
824
825 return 0;
826 }
827
828 static struct spi_driver spidev_spi_driver = {
829 .driver = {
830 .name = "spidev",
831 .of_match_table = of_match_ptr(spidev_dt_ids),
832 .acpi_match_table = ACPI_PTR(spidev_acpi_ids),
833 },
834 .probe = spidev_probe,
835 .remove = spidev_remove,
836
837 /* NOTE: suspend/resume methods are not necessary here.
838 * We don't do anything except pass the requests to/from
839 * the underlying controller. The refrigerator handles
840 * most issues; the controller driver handles the rest.
841 */
842 };
843
844 /*-------------------------------------------------------------------------*/
845
846 static int __init spidev_init(void)
847 {
848 int status;
849
850 /* Claim our 256 reserved device numbers. Then register a class
851 * that will key udev/mdev to add/remove /dev nodes. Last, register
852 * the driver which manages those device numbers.
853 */
854 BUILD_BUG_ON(N_SPI_MINORS > 256);
855 status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);
856 if (status < 0)
857 return status;
858
859 spidev_class = class_create(THIS_MODULE, "spidev");
860 if (IS_ERR(spidev_class)) {
861 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
862 return PTR_ERR(spidev_class);
863 }
864
865 status = spi_register_driver(&spidev_spi_driver);
866 if (status < 0) {
867 class_destroy(spidev_class);
868 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
869 }
870 return status;
871 }
872 module_init(spidev_init);
873
874 static void __exit spidev_exit(void)
875 {
876 spi_unregister_driver(&spidev_spi_driver);
877 class_destroy(spidev_class);
878 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
879 }
880 module_exit(spidev_exit);
881
882 MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>");
883 MODULE_DESCRIPTION("User mode SPI device interface");
884 MODULE_LICENSE("GPL");
885 MODULE_ALIAS("spi:spidev");
Linux kernel - Deliverables
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