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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
35#include <linux/spi/spi.h>
36#include <linux/spi/spidev.h>
37
38#include <asm/uaccess.h>
39
40
41/*
42 * This supports access to SPI devices using normal userspace I/O calls.
43 * Note that while traditional UNIX/POSIX I/O semantics are half duplex,
44 * and often mask message boundaries, full SPI support requires full duplex
45 * transfers. There are several kinds of internal message boundaries to
46 * handle chipselect management and other protocol options.
47 *
48 * SPI has a character major number assigned. We allocate minor numbers
49 * dynamically using a bitmask. You must use hotplug tools, such as udev
50 * (or mdev with busybox) to create and destroy the /dev/spidevB.C device
51 * nodes, since there is no fixed association of minor numbers with any
52 * particular SPI bus or device.
53 */
54#define SPIDEV_MAJOR 153 /* assigned */
55#define N_SPI_MINORS 32 /* ... up to 256 */
56
57static DECLARE_BITMAP(minors, N_SPI_MINORS);
58
59
60/* Bit masks for spi_device.mode management. Note that incorrect
61 * settings for some settings can cause *lots* of trouble for other
62 * devices on a shared bus:
63 *
64 * - CS_HIGH ... this device will be active when it shouldn't be
65 * - 3WIRE ... when active, it won't behave as it should
66 * - NO_CS ... there will be no explicit message boundaries; this
67 * is completely incompatible with the shared bus model
68 * - READY ... transfers may proceed when they shouldn't.
69 *
70 * REVISIT should changing those flags be privileged?
71 */
72#define SPI_MODE_MASK (SPI_CPHA | SPI_CPOL | SPI_CS_HIGH \
73 | SPI_LSB_FIRST | SPI_3WIRE | SPI_LOOP \
74 | SPI_NO_CS | SPI_READY)
75
76struct spidev_data {
77 dev_t devt;
78 spinlock_t spi_lock;
79 struct spi_device *spi;
80 struct list_head device_entry;
81
82 /* buffer is NULL unless this device is open (users > 0) */
83 struct mutex buf_lock;
84 unsigned users;
85 u8 *buffer;
86};
87
88static LIST_HEAD(device_list);
89static DEFINE_MUTEX(device_list_lock);
90
91static unsigned bufsiz = 4096;
92module_param(bufsiz, uint, S_IRUGO);
93MODULE_PARM_DESC(bufsiz, "data bytes in biggest supported SPI message");
94
95/*-------------------------------------------------------------------------*/
96
97/*
98 * We can't use the standard synchronous wrappers for file I/O; we
99 * need to protect against async removal of the underlying spi_device.
100 */
101static void spidev_complete(void *arg)
102{
103 complete(arg);
104}
105
106static ssize_t
107spidev_sync(struct spidev_data *spidev, struct spi_message *message)
108{
109 DECLARE_COMPLETION_ONSTACK(done);
110 int status;
111
112 message->complete = spidev_complete;
113 message->context = &done;
114
115 spin_lock_irq(&spidev->spi_lock);
116 if (spidev->spi == NULL)
117 status = -ESHUTDOWN;
118 else
119 status = spi_async(spidev->spi, message);
120 spin_unlock_irq(&spidev->spi_lock);
121
122 if (status == 0) {
123 wait_for_completion(&done);
124 status = message->status;
125 if (status == 0)
126 status = message->actual_length;
127 }
128 return status;
129}
130
131static inline ssize_t
132spidev_sync_write(struct spidev_data *spidev, size_t len)
133{
134 struct spi_transfer t = {
135 .tx_buf = spidev->buffer,
136 .len = len,
137 };
138 struct spi_message m;
139
140 spi_message_init(&m);
141 spi_message_add_tail(&t, &m);
142 return spidev_sync(spidev, &m);
143}
144
145static inline ssize_t
146spidev_sync_read(struct spidev_data *spidev, size_t len)
147{
148 struct spi_transfer t = {
149 .rx_buf = spidev->buffer,
150 .len = len,
151 };
152 struct spi_message m;
153
154 spi_message_init(&m);
155 spi_message_add_tail(&t, &m);
156 return spidev_sync(spidev, &m);
157}
158
159/*-------------------------------------------------------------------------*/
160
161/* Read-only message with current device setup */
162static ssize_t
163spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
164{
165 struct spidev_data *spidev;
166 ssize_t status = 0;
167
168 /* chipselect only toggles at start or end of operation */
169 if (count > bufsiz)
170 return -EMSGSIZE;
171
172 spidev = filp->private_data;
173
174 mutex_lock(&spidev->buf_lock);
175 status = spidev_sync_read(spidev, count);
176 if (status > 0) {
177 unsigned long missing;
178
179 missing = copy_to_user(buf, spidev->buffer, status);
180 if (missing == status)
181 status = -EFAULT;
182 else
183 status = status - missing;
184 }
185 mutex_unlock(&spidev->buf_lock);
186
187 return status;
188}
189
190/* Write-only message with current device setup */
191static ssize_t
192spidev_write(struct file *filp, const char __user *buf,
193 size_t count, loff_t *f_pos)
194{
195 struct spidev_data *spidev;
196 ssize_t status = 0;
197 unsigned long missing;
198
199 /* chipselect only toggles at start or end of operation */
200 if (count > bufsiz)
201 return -EMSGSIZE;
202
203 spidev = filp->private_data;
204
205 mutex_lock(&spidev->buf_lock);
206 missing = copy_from_user(spidev->buffer, buf, count);
207 if (missing == 0) {
208 status = spidev_sync_write(spidev, count);
209 } else
210 status = -EFAULT;
211 mutex_unlock(&spidev->buf_lock);
212
213 return status;
214}
215
216static int spidev_message(struct spidev_data *spidev,
217 struct spi_ioc_transfer *u_xfers, unsigned n_xfers)
218{
219 struct spi_message msg;
220 struct spi_transfer *k_xfers;
221 struct spi_transfer *k_tmp;
222 struct spi_ioc_transfer *u_tmp;
223 unsigned n, total;
224 u8 *buf;
225 int status = -EFAULT;
226
227 spi_message_init(&msg);
228 k_xfers = kcalloc(n_xfers, sizeof(*k_tmp), GFP_KERNEL);
229 if (k_xfers == NULL)
230 return -ENOMEM;
231
232 /* Construct spi_message, copying any tx data to bounce buffer.
233 * We walk the array of user-provided transfers, using each one
234 * to initialize a kernel version of the same transfer.
235 */
236 buf = spidev->buffer;
237 total = 0;
238 for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers;
239 n;
240 n--, k_tmp++, u_tmp++) {
241 k_tmp->len = u_tmp->len;
242
243 total += k_tmp->len;
244 if (total > bufsiz) {
245 status = -EMSGSIZE;
246 goto done;
247 }
248
249 if (u_tmp->rx_buf) {
250 k_tmp->rx_buf = buf;
251 if (!access_ok(VERIFY_WRITE, (u8 __user *)
252 (uintptr_t) u_tmp->rx_buf,
253 u_tmp->len))
254 goto done;
255 }
256 if (u_tmp->tx_buf) {
257 k_tmp->tx_buf = buf;
258 if (copy_from_user(buf, (const u8 __user *)
259 (uintptr_t) u_tmp->tx_buf,
260 u_tmp->len))
261 goto done;
262 }
263 buf += k_tmp->len;
264
265 k_tmp->cs_change = !!u_tmp->cs_change;
266 k_tmp->bits_per_word = u_tmp->bits_per_word;
267 k_tmp->delay_usecs = u_tmp->delay_usecs;
268 k_tmp->speed_hz = u_tmp->speed_hz;
269#ifdef VERBOSE
270 dev_dbg(&spidev->spi->dev,
271 " xfer len %zd %s%s%s%dbits %u usec %uHz\n",
272 u_tmp->len,
273 u_tmp->rx_buf ? "rx " : "",
274 u_tmp->tx_buf ? "tx " : "",
275 u_tmp->cs_change ? "cs " : "",
276 u_tmp->bits_per_word ? : spidev->spi->bits_per_word,
277 u_tmp->delay_usecs,
278 u_tmp->speed_hz ? : spidev->spi->max_speed_hz);
279#endif
280 spi_message_add_tail(k_tmp, &msg);
281 }
282
283 status = spidev_sync(spidev, &msg);
284 if (status < 0)
285 goto done;
286
287 /* copy any rx data out of bounce buffer */
288 buf = spidev->buffer;
289 for (n = n_xfers, u_tmp = u_xfers; n; n--, u_tmp++) {
290 if (u_tmp->rx_buf) {
291 if (__copy_to_user((u8 __user *)
292 (uintptr_t) u_tmp->rx_buf, buf,
293 u_tmp->len)) {
294 status = -EFAULT;
295 goto done;
296 }
297 }
298 buf += u_tmp->len;
299 }
300 status = total;
301
302done:
303 kfree(k_xfers);
304 return status;
305}
306
307static long
308spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
309{
310 int err = 0;
311 int retval = 0;
312 struct spidev_data *spidev;
313 struct spi_device *spi;
314 u32 tmp;
315 unsigned n_ioc;
316 struct spi_ioc_transfer *ioc;
317
318 /* Check type and command number */
319 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC)
320 return -ENOTTY;
321
322 /* Check access direction once here; don't repeat below.
323 * IOC_DIR is from the user perspective, while access_ok is
324 * from the kernel perspective; so they look reversed.
325 */
326 if (_IOC_DIR(cmd) & _IOC_READ)
327 err = !access_ok(VERIFY_WRITE,
328 (void __user *)arg, _IOC_SIZE(cmd));
329 if (err == 0 && _IOC_DIR(cmd) & _IOC_WRITE)
330 err = !access_ok(VERIFY_READ,
331 (void __user *)arg, _IOC_SIZE(cmd));
332 if (err)
333 return -EFAULT;
334
335 /* guard against device removal before, or while,
336 * we issue this ioctl.
337 */
338 spidev = filp->private_data;
339 spin_lock_irq(&spidev->spi_lock);
340 spi = spi_dev_get(spidev->spi);
341 spin_unlock_irq(&spidev->spi_lock);
342
343 if (spi == NULL)
344 return -ESHUTDOWN;
345
346 /* use the buffer lock here for triple duty:
347 * - prevent I/O (from us) so calling spi_setup() is safe;
348 * - prevent concurrent SPI_IOC_WR_* from morphing
349 * data fields while SPI_IOC_RD_* reads them;
350 * - SPI_IOC_MESSAGE needs the buffer locked "normally".
351 */
352 mutex_lock(&spidev->buf_lock);
353
354 switch (cmd) {
355 /* read requests */
356 case SPI_IOC_RD_MODE:
357 retval = __put_user(spi->mode & SPI_MODE_MASK,
358 (__u8 __user *)arg);
359 break;
360 case SPI_IOC_RD_LSB_FIRST:
361 retval = __put_user((spi->mode & SPI_LSB_FIRST) ? 1 : 0,
362 (__u8 __user *)arg);
363 break;
364 case SPI_IOC_RD_BITS_PER_WORD:
365 retval = __put_user(spi->bits_per_word, (__u8 __user *)arg);
366 break;
367 case SPI_IOC_RD_MAX_SPEED_HZ:
368 retval = __put_user(spi->max_speed_hz, (__u32 __user *)arg);
369 break;
370
371 /* write requests */
372 case SPI_IOC_WR_MODE:
373 retval = __get_user(tmp, (u8 __user *)arg);
374 if (retval == 0) {
375 u8 save = spi->mode;
376
377 if (tmp & ~SPI_MODE_MASK) {
378 retval = -EINVAL;
379 break;
380 }
381
382 tmp |= spi->mode & ~SPI_MODE_MASK;
383 spi->mode = (u8)tmp;
384 retval = spi_setup(spi);
385 if (retval < 0)
386 spi->mode = save;
387 else
388 dev_dbg(&spi->dev, "spi mode %02x\n", tmp);
389 }
390 break;
391 case SPI_IOC_WR_LSB_FIRST:
392 retval = __get_user(tmp, (__u8 __user *)arg);
393 if (retval == 0) {
394 u8 save = spi->mode;
395
396 if (tmp)
397 spi->mode |= SPI_LSB_FIRST;
398 else
399 spi->mode &= ~SPI_LSB_FIRST;
400 retval = spi_setup(spi);
401 if (retval < 0)
402 spi->mode = save;
403 else
404 dev_dbg(&spi->dev, "%csb first\n",
405 tmp ? 'l' : 'm');
406 }
407 break;
408 case SPI_IOC_WR_BITS_PER_WORD:
409 retval = __get_user(tmp, (__u8 __user *)arg);
410 if (retval == 0) {
411 u8 save = spi->bits_per_word;
412
413 spi->bits_per_word = tmp;
414 retval = spi_setup(spi);
415 if (retval < 0)
416 spi->bits_per_word = save;
417 else
418 dev_dbg(&spi->dev, "%d bits per word\n", tmp);
419 }
420 break;
421 case SPI_IOC_WR_MAX_SPEED_HZ:
422 retval = __get_user(tmp, (__u32 __user *)arg);
423 if (retval == 0) {
424 u32 save = spi->max_speed_hz;
425
426 spi->max_speed_hz = tmp;
427 retval = spi_setup(spi);
428 if (retval < 0)
429 spi->max_speed_hz = save;
430 else
431 dev_dbg(&spi->dev, "%d Hz (max)\n", tmp);
432 }
433 break;
434
435 default:
436 /* segmented and/or full-duplex I/O request */
437 if (_IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0))
438 || _IOC_DIR(cmd) != _IOC_WRITE) {
439 retval = -ENOTTY;
440 break;
441 }
442
443 tmp = _IOC_SIZE(cmd);
444 if ((tmp % sizeof(struct spi_ioc_transfer)) != 0) {
445 retval = -EINVAL;
446 break;
447 }
448 n_ioc = tmp / sizeof(struct spi_ioc_transfer);
449 if (n_ioc == 0)
450 break;
451
452 /* copy into scratch area */
453 ioc = kmalloc(tmp, GFP_KERNEL);
454 if (!ioc) {
455 retval = -ENOMEM;
456 break;
457 }
458 if (__copy_from_user(ioc, (void __user *)arg, tmp)) {
459 kfree(ioc);
460 retval = -EFAULT;
461 break;
462 }
463
464 /* translate to spi_message, execute */
465 retval = spidev_message(spidev, ioc, n_ioc);
466 kfree(ioc);
467 break;
468 }
469
470 mutex_unlock(&spidev->buf_lock);
471 spi_dev_put(spi);
472 return retval;
473}
474
475#ifdef CONFIG_COMPAT
476static long
477spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
478{
479 return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
480}
481#else
482#define spidev_compat_ioctl NULL
483#endif /* CONFIG_COMPAT */
484
485static int spidev_open(struct inode *inode, struct file *filp)
486{
487 struct spidev_data *spidev;
488 int status = -ENXIO;
489
490 mutex_lock(&device_list_lock);
491
492 list_for_each_entry(spidev, &device_list, device_entry) {
493 if (spidev->devt == inode->i_rdev) {
494 status = 0;
495 break;
496 }
497 }
498 if (status == 0) {
499 if (!spidev->buffer) {
500 spidev->buffer = kmalloc(bufsiz, GFP_KERNEL);
501 if (!spidev->buffer) {
502 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
503 status = -ENOMEM;
504 }
505 }
506 if (status == 0) {
507 spidev->users++;
508 filp->private_data = spidev;
509 nonseekable_open(inode, filp);
510 }
511 } else
512 pr_debug("spidev: nothing for minor %d\n", iminor(inode));
513
514 mutex_unlock(&device_list_lock);
515 return status;
516}
517
518static int spidev_release(struct inode *inode, struct file *filp)
519{
520 struct spidev_data *spidev;
521 int status = 0;
522
523 mutex_lock(&device_list_lock);
524 spidev = filp->private_data;
525 filp->private_data = NULL;
526
527 /* last close? */
528 spidev->users--;
529 if (!spidev->users) {
530 int dofree;
531
532 kfree(spidev->buffer);
533 spidev->buffer = NULL;
534
535 /* ... after we unbound from the underlying device? */
536 spin_lock_irq(&spidev->spi_lock);
537 dofree = (spidev->spi == NULL);
538 spin_unlock_irq(&spidev->spi_lock);
539
540 if (dofree)
541 kfree(spidev);
542 }
543 mutex_unlock(&device_list_lock);
544
545 return status;
546}
547
548static const struct file_operations spidev_fops = {
549 .owner = THIS_MODULE,
550 /* REVISIT switch to aio primitives, so that userspace
551 * gets more complete API coverage. It'll simplify things
552 * too, except for the locking.
553 */
554 .write = spidev_write,
555 .read = spidev_read,
556 .unlocked_ioctl = spidev_ioctl,
557 .compat_ioctl = spidev_compat_ioctl,
558 .open = spidev_open,
559 .release = spidev_release,
560 .llseek = no_llseek,
561};
562
563/*-------------------------------------------------------------------------*/
564
565/* The main reason to have this class is to make mdev/udev create the
566 * /dev/spidevB.C character device nodes exposing our userspace API.
567 * It also simplifies memory management.
568 */
569
570static struct class *spidev_class;
571
572/*-------------------------------------------------------------------------*/
573
574static int __devinit spidev_probe(struct spi_device *spi)
575{
576 struct spidev_data *spidev;
577 int status;
578 unsigned long minor;
579
580 /* Allocate driver data */
581 spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);
582 if (!spidev)
583 return -ENOMEM;
584
585 /* Initialize the driver data */
586 spidev->spi = spi;
587 spin_lock_init(&spidev->spi_lock);
588 mutex_init(&spidev->buf_lock);
589
590 INIT_LIST_HEAD(&spidev->device_entry);
591
592 /* If we can allocate a minor number, hook up this device.
593 * Reusing minors is fine so long as udev or mdev is working.
594 */
595 mutex_lock(&device_list_lock);
596 minor = find_first_zero_bit(minors, N_SPI_MINORS);
597 if (minor < N_SPI_MINORS) {
598 struct device *dev;
599
600 spidev->devt = MKDEV(SPIDEV_MAJOR, minor);
601 dev = device_create(spidev_class, &spi->dev, spidev->devt,
602 spidev, "spidev%d.%d",
603 spi->master->bus_num, spi->chip_select);
604 status = IS_ERR(dev) ? PTR_ERR(dev) : 0;
605 } else {
606 dev_dbg(&spi->dev, "no minor number available!\n");
607 status = -ENODEV;
608 }
609 if (status == 0) {
610 set_bit(minor, minors);
611 list_add(&spidev->device_entry, &device_list);
612 }
613 mutex_unlock(&device_list_lock);
614
615 if (status == 0)
616 spi_set_drvdata(spi, spidev);
617 else
618 kfree(spidev);
619
620 return status;
621}
622
623static int __devexit spidev_remove(struct spi_device *spi)
624{
625 struct spidev_data *spidev = spi_get_drvdata(spi);
626
627 /* make sure ops on existing fds can abort cleanly */
628 spin_lock_irq(&spidev->spi_lock);
629 spidev->spi = NULL;
630 spi_set_drvdata(spi, NULL);
631 spin_unlock_irq(&spidev->spi_lock);
632
633 /* prevent new opens */
634 mutex_lock(&device_list_lock);
635 list_del(&spidev->device_entry);
636 device_destroy(spidev_class, spidev->devt);
637 clear_bit(MINOR(spidev->devt), minors);
638 if (spidev->users == 0)
639 kfree(spidev);
640 mutex_unlock(&device_list_lock);
641
642 return 0;
643}
644
645static struct spi_driver spidev_spi_driver = {
646 .driver = {
647 .name = "spidev",
648 .owner = THIS_MODULE,
649 },
650 .probe = spidev_probe,
651 .remove = __devexit_p(spidev_remove),
652
653 /* NOTE: suspend/resume methods are not necessary here.
654 * We don't do anything except pass the requests to/from
655 * the underlying controller. The refrigerator handles
656 * most issues; the controller driver handles the rest.
657 */
658};
659
660/*-------------------------------------------------------------------------*/
661
662static int __init spidev_init(void)
663{
664 int status;
665
666 /* Claim our 256 reserved device numbers. Then register a class
667 * that will key udev/mdev to add/remove /dev nodes. Last, register
668 * the driver which manages those device numbers.
669 */
670 BUILD_BUG_ON(N_SPI_MINORS > 256);
671 status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);
672 if (status < 0)
673 return status;
674
675 spidev_class = class_create(THIS_MODULE, "spidev");
676 if (IS_ERR(spidev_class)) {
677 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
678 return PTR_ERR(spidev_class);
679 }
680
681 status = spi_register_driver(&spidev_spi_driver);
682 if (status < 0) {
683 class_destroy(spidev_class);
684 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
685 }
686 return status;
687}
688module_init(spidev_init);
689
690static void __exit spidev_exit(void)
691{
692 spi_unregister_driver(&spidev_spi_driver);
693 class_destroy(spidev_class);
694 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
695}
696module_exit(spidev_exit);
697
698MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>");
699MODULE_DESCRIPTION("User mode SPI device interface");
700MODULE_LICENSE("GPL");
701MODULE_ALIAS("spi:spidev");
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
56static 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
76struct 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
90static LIST_HEAD(device_list);
91static DEFINE_MUTEX(device_list_lock);
92
93static unsigned bufsiz = 4096;
94module_param(bufsiz, uint, S_IRUGO);
95MODULE_PARM_DESC(bufsiz, "data bytes in biggest supported SPI message");
96
97/*-------------------------------------------------------------------------*/
98
99static ssize_t
100spidev_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
121static inline ssize_t
122spidev_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
136static inline ssize_t
137spidev_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 */
154static ssize_t
155spidev_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 */
183static ssize_t
184spidev_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
208static 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
319done:
320 kfree(k_xfers);
321 return status;
322}
323
324static struct spi_ioc_transfer *
325spidev_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
355static long
356spidev_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
516static long
517spidev_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
564done:
565 mutex_unlock(&spidev->buf_lock);
566 spi_dev_put(spi);
567 return retval;
568}
569
570static long
571spidev_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
584static 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
628err_alloc_rx_buf:
629 kfree(spidev->tx_buffer);
630 spidev->tx_buffer = NULL;
631err_find_dev:
632 mutex_unlock(&device_list_lock);
633 return status;
634}
635
636static 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
671static 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
693static struct class *spidev_class;
694
695#ifdef CONFIG_OF
696static const struct of_device_id spidev_dt_ids[] = {
697 { .compatible = "rohm,dh2228fv" },
698 { .compatible = "lineartechnology,ltc2488" },
699 { .compatible = "ge,achc" },
700 {},
701};
702MODULE_DEVICE_TABLE(of, spidev_dt_ids);
703#endif
704
705#ifdef CONFIG_ACPI
706
707/* Dummy SPI devices not to be used in production systems */
708#define SPIDEV_ACPI_DUMMY 1
709
710static const struct acpi_device_id spidev_acpi_ids[] = {
711 /*
712 * The ACPI SPT000* devices are only meant for development and
713 * testing. Systems used in production should have a proper ACPI
714 * description of the connected peripheral and they should also use
715 * a proper driver instead of poking directly to the SPI bus.
716 */
717 { "SPT0001", SPIDEV_ACPI_DUMMY },
718 { "SPT0002", SPIDEV_ACPI_DUMMY },
719 { "SPT0003", SPIDEV_ACPI_DUMMY },
720 {},
721};
722MODULE_DEVICE_TABLE(acpi, spidev_acpi_ids);
723
724static void spidev_probe_acpi(struct spi_device *spi)
725{
726 const struct acpi_device_id *id;
727
728 if (!has_acpi_companion(&spi->dev))
729 return;
730
731 id = acpi_match_device(spidev_acpi_ids, &spi->dev);
732 if (WARN_ON(!id))
733 return;
734
735 if (id->driver_data == SPIDEV_ACPI_DUMMY)
736 dev_warn(&spi->dev, "do not use this driver in production systems!\n");
737}
738#else
739static inline void spidev_probe_acpi(struct spi_device *spi) {}
740#endif
741
742/*-------------------------------------------------------------------------*/
743
744static int spidev_probe(struct spi_device *spi)
745{
746 struct spidev_data *spidev;
747 int status;
748 unsigned long minor;
749
750 /*
751 * spidev should never be referenced in DT without a specific
752 * compatible string, it is a Linux implementation thing
753 * rather than a description of the hardware.
754 */
755 if (spi->dev.of_node && !of_match_device(spidev_dt_ids, &spi->dev)) {
756 dev_err(&spi->dev, "buggy DT: spidev listed directly in DT\n");
757 WARN_ON(spi->dev.of_node &&
758 !of_match_device(spidev_dt_ids, &spi->dev));
759 }
760
761 spidev_probe_acpi(spi);
762
763 /* Allocate driver data */
764 spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);
765 if (!spidev)
766 return -ENOMEM;
767
768 /* Initialize the driver data */
769 spidev->spi = spi;
770 spin_lock_init(&spidev->spi_lock);
771 mutex_init(&spidev->buf_lock);
772
773 INIT_LIST_HEAD(&spidev->device_entry);
774
775 /* If we can allocate a minor number, hook up this device.
776 * Reusing minors is fine so long as udev or mdev is working.
777 */
778 mutex_lock(&device_list_lock);
779 minor = find_first_zero_bit(minors, N_SPI_MINORS);
780 if (minor < N_SPI_MINORS) {
781 struct device *dev;
782
783 spidev->devt = MKDEV(SPIDEV_MAJOR, minor);
784 dev = device_create(spidev_class, &spi->dev, spidev->devt,
785 spidev, "spidev%d.%d",
786 spi->master->bus_num, spi->chip_select);
787 status = PTR_ERR_OR_ZERO(dev);
788 } else {
789 dev_dbg(&spi->dev, "no minor number available!\n");
790 status = -ENODEV;
791 }
792 if (status == 0) {
793 set_bit(minor, minors);
794 list_add(&spidev->device_entry, &device_list);
795 }
796 mutex_unlock(&device_list_lock);
797
798 spidev->speed_hz = spi->max_speed_hz;
799
800 if (status == 0)
801 spi_set_drvdata(spi, spidev);
802 else
803 kfree(spidev);
804
805 return status;
806}
807
808static int spidev_remove(struct spi_device *spi)
809{
810 struct spidev_data *spidev = spi_get_drvdata(spi);
811
812 /* make sure ops on existing fds can abort cleanly */
813 spin_lock_irq(&spidev->spi_lock);
814 spidev->spi = NULL;
815 spin_unlock_irq(&spidev->spi_lock);
816
817 /* prevent new opens */
818 mutex_lock(&device_list_lock);
819 list_del(&spidev->device_entry);
820 device_destroy(spidev_class, spidev->devt);
821 clear_bit(MINOR(spidev->devt), minors);
822 if (spidev->users == 0)
823 kfree(spidev);
824 mutex_unlock(&device_list_lock);
825
826 return 0;
827}
828
829static struct spi_driver spidev_spi_driver = {
830 .driver = {
831 .name = "spidev",
832 .of_match_table = of_match_ptr(spidev_dt_ids),
833 .acpi_match_table = ACPI_PTR(spidev_acpi_ids),
834 },
835 .probe = spidev_probe,
836 .remove = spidev_remove,
837
838 /* NOTE: suspend/resume methods are not necessary here.
839 * We don't do anything except pass the requests to/from
840 * the underlying controller. The refrigerator handles
841 * most issues; the controller driver handles the rest.
842 */
843};
844
845/*-------------------------------------------------------------------------*/
846
847static int __init spidev_init(void)
848{
849 int status;
850
851 /* Claim our 256 reserved device numbers. Then register a class
852 * that will key udev/mdev to add/remove /dev nodes. Last, register
853 * the driver which manages those device numbers.
854 */
855 BUILD_BUG_ON(N_SPI_MINORS > 256);
856 status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);
857 if (status < 0)
858 return status;
859
860 spidev_class = class_create(THIS_MODULE, "spidev");
861 if (IS_ERR(spidev_class)) {
862 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
863 return PTR_ERR(spidev_class);
864 }
865
866 status = spi_register_driver(&spidev_spi_driver);
867 if (status < 0) {
868 class_destroy(spidev_class);
869 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
870 }
871 return status;
872}
873module_init(spidev_init);
874
875static void __exit spidev_exit(void)
876{
877 spi_unregister_driver(&spidev_spi_driver);
878 class_destroy(spidev_class);
879 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
880}
881module_exit(spidev_exit);
882
883MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>");
884MODULE_DESCRIPTION("User mode SPI device interface");
885MODULE_LICENSE("GPL");
886MODULE_ALIAS("spi:spidev");