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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 * 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
59static 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
79struct spidev_data {
80 dev_t devt;
81 spinlock_t spi_lock;
82 struct spi_device *spi;
83 struct list_head device_entry;
84
85 /* buffer is NULL unless this device is open (users > 0) */
86 struct mutex buf_lock;
87 unsigned users;
88 u8 *buffer;
89};
90
91static LIST_HEAD(device_list);
92static DEFINE_MUTEX(device_list_lock);
93
94static unsigned bufsiz = 4096;
95module_param(bufsiz, uint, S_IRUGO);
96MODULE_PARM_DESC(bufsiz, "data bytes in biggest supported SPI message");
97
98/*-------------------------------------------------------------------------*/
99
100/*
101 * We can't use the standard synchronous wrappers for file I/O; we
102 * need to protect against async removal of the underlying spi_device.
103 */
104static void spidev_complete(void *arg)
105{
106 complete(arg);
107}
108
109static ssize_t
110spidev_sync(struct spidev_data *spidev, struct spi_message *message)
111{
112 DECLARE_COMPLETION_ONSTACK(done);
113 int status;
114
115 message->complete = spidev_complete;
116 message->context = &done;
117
118 spin_lock_irq(&spidev->spi_lock);
119 if (spidev->spi == NULL)
120 status = -ESHUTDOWN;
121 else
122 status = spi_async(spidev->spi, message);
123 spin_unlock_irq(&spidev->spi_lock);
124
125 if (status == 0) {
126 wait_for_completion(&done);
127 status = message->status;
128 if (status == 0)
129 status = message->actual_length;
130 }
131 return status;
132}
133
134static inline ssize_t
135spidev_sync_write(struct spidev_data *spidev, size_t len)
136{
137 struct spi_transfer t = {
138 .tx_buf = spidev->buffer,
139 .len = len,
140 };
141 struct spi_message m;
142
143 spi_message_init(&m);
144 spi_message_add_tail(&t, &m);
145 return spidev_sync(spidev, &m);
146}
147
148static inline ssize_t
149spidev_sync_read(struct spidev_data *spidev, size_t len)
150{
151 struct spi_transfer t = {
152 .rx_buf = spidev->buffer,
153 .len = len,
154 };
155 struct spi_message m;
156
157 spi_message_init(&m);
158 spi_message_add_tail(&t, &m);
159 return spidev_sync(spidev, &m);
160}
161
162/*-------------------------------------------------------------------------*/
163
164/* Read-only message with current device setup */
165static ssize_t
166spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
167{
168 struct spidev_data *spidev;
169 ssize_t status = 0;
170
171 /* chipselect only toggles at start or end of operation */
172 if (count > bufsiz)
173 return -EMSGSIZE;
174
175 spidev = filp->private_data;
176
177 mutex_lock(&spidev->buf_lock);
178 status = spidev_sync_read(spidev, count);
179 if (status > 0) {
180 unsigned long missing;
181
182 missing = copy_to_user(buf, spidev->buffer, status);
183 if (missing == status)
184 status = -EFAULT;
185 else
186 status = status - missing;
187 }
188 mutex_unlock(&spidev->buf_lock);
189
190 return status;
191}
192
193/* Write-only message with current device setup */
194static ssize_t
195spidev_write(struct file *filp, const char __user *buf,
196 size_t count, loff_t *f_pos)
197{
198 struct spidev_data *spidev;
199 ssize_t status = 0;
200 unsigned long missing;
201
202 /* chipselect only toggles at start or end of operation */
203 if (count > bufsiz)
204 return -EMSGSIZE;
205
206 spidev = filp->private_data;
207
208 mutex_lock(&spidev->buf_lock);
209 missing = copy_from_user(spidev->buffer, buf, count);
210 if (missing == 0)
211 status = spidev_sync_write(spidev, count);
212 else
213 status = -EFAULT;
214 mutex_unlock(&spidev->buf_lock);
215
216 return status;
217}
218
219static int spidev_message(struct spidev_data *spidev,
220 struct spi_ioc_transfer *u_xfers, unsigned n_xfers)
221{
222 struct spi_message msg;
223 struct spi_transfer *k_xfers;
224 struct spi_transfer *k_tmp;
225 struct spi_ioc_transfer *u_tmp;
226 unsigned n, total;
227 u8 *buf;
228 int status = -EFAULT;
229
230 spi_message_init(&msg);
231 k_xfers = kcalloc(n_xfers, sizeof(*k_tmp), GFP_KERNEL);
232 if (k_xfers == NULL)
233 return -ENOMEM;
234
235 /* Construct spi_message, copying any tx data to bounce buffer.
236 * We walk the array of user-provided transfers, using each one
237 * to initialize a kernel version of the same transfer.
238 */
239 buf = spidev->buffer;
240 total = 0;
241 for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers;
242 n;
243 n--, k_tmp++, u_tmp++) {
244 k_tmp->len = u_tmp->len;
245
246 total += k_tmp->len;
247 if (total > bufsiz) {
248 status = -EMSGSIZE;
249 goto done;
250 }
251
252 if (u_tmp->rx_buf) {
253 k_tmp->rx_buf = buf;
254 if (!access_ok(VERIFY_WRITE, (u8 __user *)
255 (uintptr_t) u_tmp->rx_buf,
256 u_tmp->len))
257 goto done;
258 }
259 if (u_tmp->tx_buf) {
260 k_tmp->tx_buf = buf;
261 if (copy_from_user(buf, (const u8 __user *)
262 (uintptr_t) u_tmp->tx_buf,
263 u_tmp->len))
264 goto done;
265 }
266 buf += k_tmp->len;
267
268 k_tmp->cs_change = !!u_tmp->cs_change;
269 k_tmp->tx_nbits = u_tmp->tx_nbits;
270 k_tmp->rx_nbits = u_tmp->rx_nbits;
271 k_tmp->bits_per_word = u_tmp->bits_per_word;
272 k_tmp->delay_usecs = u_tmp->delay_usecs;
273 k_tmp->speed_hz = u_tmp->speed_hz;
274#ifdef VERBOSE
275 dev_dbg(&spidev->spi->dev,
276 " xfer len %zd %s%s%s%dbits %u usec %uHz\n",
277 u_tmp->len,
278 u_tmp->rx_buf ? "rx " : "",
279 u_tmp->tx_buf ? "tx " : "",
280 u_tmp->cs_change ? "cs " : "",
281 u_tmp->bits_per_word ? : spidev->spi->bits_per_word,
282 u_tmp->delay_usecs,
283 u_tmp->speed_hz ? : spidev->spi->max_speed_hz);
284#endif
285 spi_message_add_tail(k_tmp, &msg);
286 }
287
288 status = spidev_sync(spidev, &msg);
289 if (status < 0)
290 goto done;
291
292 /* copy any rx data out of bounce buffer */
293 buf = spidev->buffer;
294 for (n = n_xfers, u_tmp = u_xfers; n; n--, u_tmp++) {
295 if (u_tmp->rx_buf) {
296 if (__copy_to_user((u8 __user *)
297 (uintptr_t) u_tmp->rx_buf, buf,
298 u_tmp->len)) {
299 status = -EFAULT;
300 goto done;
301 }
302 }
303 buf += u_tmp->len;
304 }
305 status = total;
306
307done:
308 kfree(k_xfers);
309 return status;
310}
311
312static long
313spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
314{
315 int err = 0;
316 int retval = 0;
317 struct spidev_data *spidev;
318 struct spi_device *spi;
319 u32 tmp;
320 unsigned n_ioc;
321 struct spi_ioc_transfer *ioc;
322
323 /* Check type and command number */
324 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC)
325 return -ENOTTY;
326
327 /* Check access direction once here; don't repeat below.
328 * IOC_DIR is from the user perspective, while access_ok is
329 * from the kernel perspective; so they look reversed.
330 */
331 if (_IOC_DIR(cmd) & _IOC_READ)
332 err = !access_ok(VERIFY_WRITE,
333 (void __user *)arg, _IOC_SIZE(cmd));
334 if (err == 0 && _IOC_DIR(cmd) & _IOC_WRITE)
335 err = !access_ok(VERIFY_READ,
336 (void __user *)arg, _IOC_SIZE(cmd));
337 if (err)
338 return -EFAULT;
339
340 /* guard against device removal before, or while,
341 * we issue this ioctl.
342 */
343 spidev = filp->private_data;
344 spin_lock_irq(&spidev->spi_lock);
345 spi = spi_dev_get(spidev->spi);
346 spin_unlock_irq(&spidev->spi_lock);
347
348 if (spi == NULL)
349 return -ESHUTDOWN;
350
351 /* use the buffer lock here for triple duty:
352 * - prevent I/O (from us) so calling spi_setup() is safe;
353 * - prevent concurrent SPI_IOC_WR_* from morphing
354 * data fields while SPI_IOC_RD_* reads them;
355 * - SPI_IOC_MESSAGE needs the buffer locked "normally".
356 */
357 mutex_lock(&spidev->buf_lock);
358
359 switch (cmd) {
360 /* read requests */
361 case SPI_IOC_RD_MODE:
362 retval = __put_user(spi->mode & SPI_MODE_MASK,
363 (__u8 __user *)arg);
364 break;
365 case SPI_IOC_RD_MODE32:
366 retval = __put_user(spi->mode & SPI_MODE_MASK,
367 (__u32 __user *)arg);
368 break;
369 case SPI_IOC_RD_LSB_FIRST:
370 retval = __put_user((spi->mode & SPI_LSB_FIRST) ? 1 : 0,
371 (__u8 __user *)arg);
372 break;
373 case SPI_IOC_RD_BITS_PER_WORD:
374 retval = __put_user(spi->bits_per_word, (__u8 __user *)arg);
375 break;
376 case SPI_IOC_RD_MAX_SPEED_HZ:
377 retval = __put_user(spi->max_speed_hz, (__u32 __user *)arg);
378 break;
379
380 /* write requests */
381 case SPI_IOC_WR_MODE:
382 case SPI_IOC_WR_MODE32:
383 if (cmd == SPI_IOC_WR_MODE)
384 retval = __get_user(tmp, (u8 __user *)arg);
385 else
386 retval = __get_user(tmp, (u32 __user *)arg);
387 if (retval == 0) {
388 u32 save = spi->mode;
389
390 if (tmp & ~SPI_MODE_MASK) {
391 retval = -EINVAL;
392 break;
393 }
394
395 tmp |= spi->mode & ~SPI_MODE_MASK;
396 spi->mode = (u16)tmp;
397 retval = spi_setup(spi);
398 if (retval < 0)
399 spi->mode = save;
400 else
401 dev_dbg(&spi->dev, "spi mode %x\n", tmp);
402 }
403 break;
404 case SPI_IOC_WR_LSB_FIRST:
405 retval = __get_user(tmp, (__u8 __user *)arg);
406 if (retval == 0) {
407 u32 save = spi->mode;
408
409 if (tmp)
410 spi->mode |= SPI_LSB_FIRST;
411 else
412 spi->mode &= ~SPI_LSB_FIRST;
413 retval = spi_setup(spi);
414 if (retval < 0)
415 spi->mode = save;
416 else
417 dev_dbg(&spi->dev, "%csb first\n",
418 tmp ? 'l' : 'm');
419 }
420 break;
421 case SPI_IOC_WR_BITS_PER_WORD:
422 retval = __get_user(tmp, (__u8 __user *)arg);
423 if (retval == 0) {
424 u8 save = spi->bits_per_word;
425
426 spi->bits_per_word = tmp;
427 retval = spi_setup(spi);
428 if (retval < 0)
429 spi->bits_per_word = save;
430 else
431 dev_dbg(&spi->dev, "%d bits per word\n", tmp);
432 }
433 break;
434 case SPI_IOC_WR_MAX_SPEED_HZ:
435 retval = __get_user(tmp, (__u32 __user *)arg);
436 if (retval == 0) {
437 u32 save = spi->max_speed_hz;
438
439 spi->max_speed_hz = tmp;
440 retval = spi_setup(spi);
441 if (retval < 0)
442 spi->max_speed_hz = save;
443 else
444 dev_dbg(&spi->dev, "%d Hz (max)\n", tmp);
445 }
446 break;
447
448 default:
449 /* segmented and/or full-duplex I/O request */
450 if (_IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0))
451 || _IOC_DIR(cmd) != _IOC_WRITE) {
452 retval = -ENOTTY;
453 break;
454 }
455
456 tmp = _IOC_SIZE(cmd);
457 if ((tmp % sizeof(struct spi_ioc_transfer)) != 0) {
458 retval = -EINVAL;
459 break;
460 }
461 n_ioc = tmp / sizeof(struct spi_ioc_transfer);
462 if (n_ioc == 0)
463 break;
464
465 /* copy into scratch area */
466 ioc = kmalloc(tmp, GFP_KERNEL);
467 if (!ioc) {
468 retval = -ENOMEM;
469 break;
470 }
471 if (__copy_from_user(ioc, (void __user *)arg, tmp)) {
472 kfree(ioc);
473 retval = -EFAULT;
474 break;
475 }
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
489static long
490spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
491{
492 return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
493}
494#else
495#define spidev_compat_ioctl NULL
496#endif /* CONFIG_COMPAT */
497
498static int spidev_open(struct inode *inode, struct file *filp)
499{
500 struct spidev_data *spidev;
501 int status = -ENXIO;
502
503 mutex_lock(&device_list_lock);
504
505 list_for_each_entry(spidev, &device_list, device_entry) {
506 if (spidev->devt == inode->i_rdev) {
507 status = 0;
508 break;
509 }
510 }
511 if (status == 0) {
512 if (!spidev->buffer) {
513 spidev->buffer = kmalloc(bufsiz, GFP_KERNEL);
514 if (!spidev->buffer) {
515 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
516 status = -ENOMEM;
517 }
518 }
519 if (status == 0) {
520 spidev->users++;
521 filp->private_data = spidev;
522 nonseekable_open(inode, filp);
523 }
524 } else
525 pr_debug("spidev: nothing for minor %d\n", iminor(inode));
526
527 mutex_unlock(&device_list_lock);
528 return status;
529}
530
531static int spidev_release(struct inode *inode, struct file *filp)
532{
533 struct spidev_data *spidev;
534 int status = 0;
535
536 mutex_lock(&device_list_lock);
537 spidev = filp->private_data;
538 filp->private_data = NULL;
539
540 /* last close? */
541 spidev->users--;
542 if (!spidev->users) {
543 int dofree;
544
545 kfree(spidev->buffer);
546 spidev->buffer = NULL;
547
548 /* ... after we unbound from the underlying device? */
549 spin_lock_irq(&spidev->spi_lock);
550 dofree = (spidev->spi == NULL);
551 spin_unlock_irq(&spidev->spi_lock);
552
553 if (dofree)
554 kfree(spidev);
555 }
556 mutex_unlock(&device_list_lock);
557
558 return status;
559}
560
561static const struct file_operations spidev_fops = {
562 .owner = THIS_MODULE,
563 /* REVISIT switch to aio primitives, so that userspace
564 * gets more complete API coverage. It'll simplify things
565 * too, except for the locking.
566 */
567 .write = spidev_write,
568 .read = spidev_read,
569 .unlocked_ioctl = spidev_ioctl,
570 .compat_ioctl = spidev_compat_ioctl,
571 .open = spidev_open,
572 .release = spidev_release,
573 .llseek = no_llseek,
574};
575
576/*-------------------------------------------------------------------------*/
577
578/* The main reason to have this class is to make mdev/udev create the
579 * /dev/spidevB.C character device nodes exposing our userspace API.
580 * It also simplifies memory management.
581 */
582
583static struct class *spidev_class;
584
585/*-------------------------------------------------------------------------*/
586
587static int spidev_probe(struct spi_device *spi)
588{
589 struct spidev_data *spidev;
590 int status;
591 unsigned long minor;
592
593 /* Allocate driver data */
594 spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);
595 if (!spidev)
596 return -ENOMEM;
597
598 /* Initialize the driver data */
599 spidev->spi = spi;
600 spin_lock_init(&spidev->spi_lock);
601 mutex_init(&spidev->buf_lock);
602
603 INIT_LIST_HEAD(&spidev->device_entry);
604
605 /* If we can allocate a minor number, hook up this device.
606 * Reusing minors is fine so long as udev or mdev is working.
607 */
608 mutex_lock(&device_list_lock);
609 minor = find_first_zero_bit(minors, N_SPI_MINORS);
610 if (minor < N_SPI_MINORS) {
611 struct device *dev;
612
613 spidev->devt = MKDEV(SPIDEV_MAJOR, minor);
614 dev = device_create(spidev_class, &spi->dev, spidev->devt,
615 spidev, "spidev%d.%d",
616 spi->master->bus_num, spi->chip_select);
617 status = PTR_ERR_OR_ZERO(dev);
618 } else {
619 dev_dbg(&spi->dev, "no minor number available!\n");
620 status = -ENODEV;
621 }
622 if (status == 0) {
623 set_bit(minor, minors);
624 list_add(&spidev->device_entry, &device_list);
625 }
626 mutex_unlock(&device_list_lock);
627
628 if (status == 0)
629 spi_set_drvdata(spi, spidev);
630 else
631 kfree(spidev);
632
633 return status;
634}
635
636static int spidev_remove(struct spi_device *spi)
637{
638 struct spidev_data *spidev = spi_get_drvdata(spi);
639
640 /* make sure ops on existing fds can abort cleanly */
641 spin_lock_irq(&spidev->spi_lock);
642 spidev->spi = NULL;
643 spin_unlock_irq(&spidev->spi_lock);
644
645 /* prevent new opens */
646 mutex_lock(&device_list_lock);
647 list_del(&spidev->device_entry);
648 device_destroy(spidev_class, spidev->devt);
649 clear_bit(MINOR(spidev->devt), minors);
650 if (spidev->users == 0)
651 kfree(spidev);
652 mutex_unlock(&device_list_lock);
653
654 return 0;
655}
656
657static const struct of_device_id spidev_dt_ids[] = {
658 { .compatible = "rohm,dh2228fv" },
659 {},
660};
661
662MODULE_DEVICE_TABLE(of, spidev_dt_ids);
663
664static struct spi_driver spidev_spi_driver = {
665 .driver = {
666 .name = "spidev",
667 .owner = THIS_MODULE,
668 .of_match_table = of_match_ptr(spidev_dt_ids),
669 },
670 .probe = spidev_probe,
671 .remove = spidev_remove,
672
673 /* NOTE: suspend/resume methods are not necessary here.
674 * We don't do anything except pass the requests to/from
675 * the underlying controller. The refrigerator handles
676 * most issues; the controller driver handles the rest.
677 */
678};
679
680/*-------------------------------------------------------------------------*/
681
682static int __init spidev_init(void)
683{
684 int status;
685
686 /* Claim our 256 reserved device numbers. Then register a class
687 * that will key udev/mdev to add/remove /dev nodes. Last, register
688 * the driver which manages those device numbers.
689 */
690 BUILD_BUG_ON(N_SPI_MINORS > 256);
691 status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);
692 if (status < 0)
693 return status;
694
695 spidev_class = class_create(THIS_MODULE, "spidev");
696 if (IS_ERR(spidev_class)) {
697 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
698 return PTR_ERR(spidev_class);
699 }
700
701 status = spi_register_driver(&spidev_spi_driver);
702 if (status < 0) {
703 class_destroy(spidev_class);
704 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
705 }
706 return status;
707}
708module_init(spidev_init);
709
710static void __exit spidev_exit(void)
711{
712 spi_unregister_driver(&spidev_spi_driver);
713 class_destroy(spidev_class);
714 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
715}
716module_exit(spidev_exit);
717
718MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>");
719MODULE_DESCRIPTION("User mode SPI device interface");
720MODULE_LICENSE("GPL");
721MODULE_ALIAS("spi:spidev");