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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
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
33#include <linux/spi/spi.h>
34#include <linux/spi/spidev.h>
35
36#include <linux/uaccess.h>
37
38
39/*
40 * This supports access to SPI devices using normal userspace I/O calls.
41 * Note that while traditional UNIX/POSIX I/O semantics are half duplex,
42 * and often mask message boundaries, full SPI support requires full duplex
43 * transfers. There are several kinds of internal message boundaries to
44 * handle chipselect management and other protocol options.
45 *
46 * SPI has a character major number assigned. We allocate minor numbers
47 * dynamically using a bitmask. You must use hotplug tools, such as udev
48 * (or mdev with busybox) to create and destroy the /dev/spidevB.C device
49 * nodes, since there is no fixed association of minor numbers with any
50 * particular SPI bus or device.
51 */
52#define SPIDEV_MAJOR 153 /* assigned */
53#define N_SPI_MINORS 32 /* ... up to 256 */
54
55static DECLARE_BITMAP(minors, N_SPI_MINORS);
56
57
58/* Bit masks for spi_device.mode management. Note that incorrect
59 * settings for some settings can cause *lots* of trouble for other
60 * devices on a shared bus:
61 *
62 * - CS_HIGH ... this device will be active when it shouldn't be
63 * - 3WIRE ... when active, it won't behave as it should
64 * - NO_CS ... there will be no explicit message boundaries; this
65 * is completely incompatible with the shared bus model
66 * - READY ... transfers may proceed when they shouldn't.
67 *
68 * REVISIT should changing those flags be privileged?
69 */
70#define SPI_MODE_MASK (SPI_CPHA | SPI_CPOL | SPI_CS_HIGH \
71 | SPI_LSB_FIRST | SPI_3WIRE | SPI_LOOP \
72 | SPI_NO_CS | SPI_READY | SPI_TX_DUAL \
73 | SPI_TX_QUAD | SPI_RX_DUAL | SPI_RX_QUAD)
74
75struct spidev_data {
76 dev_t devt;
77 spinlock_t spi_lock;
78 struct spi_device *spi;
79 struct list_head device_entry;
80
81 /* TX/RX buffers are NULL unless this device is open (users > 0) */
82 struct mutex buf_lock;
83 unsigned users;
84 u8 *tx_buffer;
85 u8 *rx_buffer;
86 u32 speed_hz;
87};
88
89static LIST_HEAD(device_list);
90static DEFINE_MUTEX(device_list_lock);
91
92static unsigned bufsiz = 4096;
93module_param(bufsiz, uint, S_IRUGO);
94MODULE_PARM_DESC(bufsiz, "data bytes in biggest supported SPI message");
95
96/*-------------------------------------------------------------------------*/
97
98static ssize_t
99spidev_sync(struct spidev_data *spidev, struct spi_message *message)
100{
101 DECLARE_COMPLETION_ONSTACK(done);
102 int status;
103 struct spi_device *spi;
104
105 spin_lock_irq(&spidev->spi_lock);
106 spi = spidev->spi;
107 spin_unlock_irq(&spidev->spi_lock);
108
109 if (spi == NULL)
110 status = -ESHUTDOWN;
111 else
112 status = spi_sync(spi, message);
113
114 if (status == 0)
115 status = message->actual_length;
116
117 return status;
118}
119
120static inline ssize_t
121spidev_sync_write(struct spidev_data *spidev, size_t len)
122{
123 struct spi_transfer t = {
124 .tx_buf = spidev->tx_buffer,
125 .len = len,
126 .speed_hz = spidev->speed_hz,
127 };
128 struct spi_message m;
129
130 spi_message_init(&m);
131 spi_message_add_tail(&t, &m);
132 return spidev_sync(spidev, &m);
133}
134
135static inline ssize_t
136spidev_sync_read(struct spidev_data *spidev, size_t len)
137{
138 struct spi_transfer t = {
139 .rx_buf = spidev->rx_buffer,
140 .len = len,
141 .speed_hz = spidev->speed_hz,
142 };
143 struct spi_message m;
144
145 spi_message_init(&m);
146 spi_message_add_tail(&t, &m);
147 return spidev_sync(spidev, &m);
148}
149
150/*-------------------------------------------------------------------------*/
151
152/* Read-only message with current device setup */
153static ssize_t
154spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
155{
156 struct spidev_data *spidev;
157 ssize_t status = 0;
158
159 /* chipselect only toggles at start or end of operation */
160 if (count > bufsiz)
161 return -EMSGSIZE;
162
163 spidev = filp->private_data;
164
165 mutex_lock(&spidev->buf_lock);
166 status = spidev_sync_read(spidev, count);
167 if (status > 0) {
168 unsigned long missing;
169
170 missing = copy_to_user(buf, spidev->rx_buffer, status);
171 if (missing == status)
172 status = -EFAULT;
173 else
174 status = status - missing;
175 }
176 mutex_unlock(&spidev->buf_lock);
177
178 return status;
179}
180
181/* Write-only message with current device setup */
182static ssize_t
183spidev_write(struct file *filp, const char __user *buf,
184 size_t count, loff_t *f_pos)
185{
186 struct spidev_data *spidev;
187 ssize_t status = 0;
188 unsigned long missing;
189
190 /* chipselect only toggles at start or end of operation */
191 if (count > bufsiz)
192 return -EMSGSIZE;
193
194 spidev = filp->private_data;
195
196 mutex_lock(&spidev->buf_lock);
197 missing = copy_from_user(spidev->tx_buffer, buf, count);
198 if (missing == 0)
199 status = spidev_sync_write(spidev, count);
200 else
201 status = -EFAULT;
202 mutex_unlock(&spidev->buf_lock);
203
204 return status;
205}
206
207static int spidev_message(struct spidev_data *spidev,
208 struct spi_ioc_transfer *u_xfers, unsigned n_xfers)
209{
210 struct spi_message msg;
211 struct spi_transfer *k_xfers;
212 struct spi_transfer *k_tmp;
213 struct spi_ioc_transfer *u_tmp;
214 unsigned n, total, tx_total, rx_total;
215 u8 *tx_buf, *rx_buf;
216 int status = -EFAULT;
217
218 spi_message_init(&msg);
219 k_xfers = kcalloc(n_xfers, sizeof(*k_tmp), GFP_KERNEL);
220 if (k_xfers == NULL)
221 return -ENOMEM;
222
223 /* Construct spi_message, copying any tx data to bounce buffer.
224 * We walk the array of user-provided transfers, using each one
225 * to initialize a kernel version of the same transfer.
226 */
227 tx_buf = spidev->tx_buffer;
228 rx_buf = spidev->rx_buffer;
229 total = 0;
230 tx_total = 0;
231 rx_total = 0;
232 for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers;
233 n;
234 n--, k_tmp++, u_tmp++) {
235 k_tmp->len = u_tmp->len;
236
237 total += k_tmp->len;
238 /* Since the function returns the total length of transfers
239 * on success, restrict the total to positive int values to
240 * avoid the return value looking like an error. Also check
241 * each transfer length to avoid arithmetic overflow.
242 */
243 if (total > INT_MAX || k_tmp->len > INT_MAX) {
244 status = -EMSGSIZE;
245 goto done;
246 }
247
248 if (u_tmp->rx_buf) {
249 /* this transfer needs space in RX bounce buffer */
250 rx_total += k_tmp->len;
251 if (rx_total > bufsiz) {
252 status = -EMSGSIZE;
253 goto done;
254 }
255 k_tmp->rx_buf = rx_buf;
256 if (!access_ok(VERIFY_WRITE, (u8 __user *)
257 (uintptr_t) u_tmp->rx_buf,
258 u_tmp->len))
259 goto done;
260 rx_buf += k_tmp->len;
261 }
262 if (u_tmp->tx_buf) {
263 /* this transfer needs space in TX bounce buffer */
264 tx_total += k_tmp->len;
265 if (tx_total > bufsiz) {
266 status = -EMSGSIZE;
267 goto done;
268 }
269 k_tmp->tx_buf = tx_buf;
270 if (copy_from_user(tx_buf, (const u8 __user *)
271 (uintptr_t) u_tmp->tx_buf,
272 u_tmp->len))
273 goto done;
274 tx_buf += k_tmp->len;
275 }
276
277 k_tmp->cs_change = !!u_tmp->cs_change;
278 k_tmp->tx_nbits = u_tmp->tx_nbits;
279 k_tmp->rx_nbits = u_tmp->rx_nbits;
280 k_tmp->bits_per_word = u_tmp->bits_per_word;
281 k_tmp->delay_usecs = u_tmp->delay_usecs;
282 k_tmp->speed_hz = u_tmp->speed_hz;
283 if (!k_tmp->speed_hz)
284 k_tmp->speed_hz = spidev->speed_hz;
285#ifdef VERBOSE
286 dev_dbg(&spidev->spi->dev,
287 " xfer len %u %s%s%s%dbits %u usec %uHz\n",
288 u_tmp->len,
289 u_tmp->rx_buf ? "rx " : "",
290 u_tmp->tx_buf ? "tx " : "",
291 u_tmp->cs_change ? "cs " : "",
292 u_tmp->bits_per_word ? : spidev->spi->bits_per_word,
293 u_tmp->delay_usecs,
294 u_tmp->speed_hz ? : spidev->spi->max_speed_hz);
295#endif
296 spi_message_add_tail(k_tmp, &msg);
297 }
298
299 status = spidev_sync(spidev, &msg);
300 if (status < 0)
301 goto done;
302
303 /* copy any rx data out of bounce buffer */
304 rx_buf = spidev->rx_buffer;
305 for (n = n_xfers, u_tmp = u_xfers; n; n--, u_tmp++) {
306 if (u_tmp->rx_buf) {
307 if (__copy_to_user((u8 __user *)
308 (uintptr_t) u_tmp->rx_buf, rx_buf,
309 u_tmp->len)) {
310 status = -EFAULT;
311 goto done;
312 }
313 rx_buf += u_tmp->len;
314 }
315 }
316 status = total;
317
318done:
319 kfree(k_xfers);
320 return status;
321}
322
323static struct spi_ioc_transfer *
324spidev_get_ioc_message(unsigned int cmd, struct spi_ioc_transfer __user *u_ioc,
325 unsigned *n_ioc)
326{
327 struct spi_ioc_transfer *ioc;
328 u32 tmp;
329
330 /* Check type, command number and direction */
331 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC
332 || _IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0))
333 || _IOC_DIR(cmd) != _IOC_WRITE)
334 return ERR_PTR(-ENOTTY);
335
336 tmp = _IOC_SIZE(cmd);
337 if ((tmp % sizeof(struct spi_ioc_transfer)) != 0)
338 return ERR_PTR(-EINVAL);
339 *n_ioc = tmp / sizeof(struct spi_ioc_transfer);
340 if (*n_ioc == 0)
341 return NULL;
342
343 /* copy into scratch area */
344 ioc = kmalloc(tmp, GFP_KERNEL);
345 if (!ioc)
346 return ERR_PTR(-ENOMEM);
347 if (__copy_from_user(ioc, u_ioc, tmp)) {
348 kfree(ioc);
349 return ERR_PTR(-EFAULT);
350 }
351 return ioc;
352}
353
354static long
355spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
356{
357 int err = 0;
358 int retval = 0;
359 struct spidev_data *spidev;
360 struct spi_device *spi;
361 u32 tmp;
362 unsigned n_ioc;
363 struct spi_ioc_transfer *ioc;
364
365 /* Check type and command number */
366 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC)
367 return -ENOTTY;
368
369 /* Check access direction once here; don't repeat below.
370 * IOC_DIR is from the user perspective, while access_ok is
371 * from the kernel perspective; so they look reversed.
372 */
373 if (_IOC_DIR(cmd) & _IOC_READ)
374 err = !access_ok(VERIFY_WRITE,
375 (void __user *)arg, _IOC_SIZE(cmd));
376 if (err == 0 && _IOC_DIR(cmd) & _IOC_WRITE)
377 err = !access_ok(VERIFY_READ,
378 (void __user *)arg, _IOC_SIZE(cmd));
379 if (err)
380 return -EFAULT;
381
382 /* guard against device removal before, or while,
383 * we issue this ioctl.
384 */
385 spidev = filp->private_data;
386 spin_lock_irq(&spidev->spi_lock);
387 spi = spi_dev_get(spidev->spi);
388 spin_unlock_irq(&spidev->spi_lock);
389
390 if (spi == NULL)
391 return -ESHUTDOWN;
392
393 /* use the buffer lock here for triple duty:
394 * - prevent I/O (from us) so calling spi_setup() is safe;
395 * - prevent concurrent SPI_IOC_WR_* from morphing
396 * data fields while SPI_IOC_RD_* reads them;
397 * - SPI_IOC_MESSAGE needs the buffer locked "normally".
398 */
399 mutex_lock(&spidev->buf_lock);
400
401 switch (cmd) {
402 /* read requests */
403 case SPI_IOC_RD_MODE:
404 retval = __put_user(spi->mode & SPI_MODE_MASK,
405 (__u8 __user *)arg);
406 break;
407 case SPI_IOC_RD_MODE32:
408 retval = __put_user(spi->mode & SPI_MODE_MASK,
409 (__u32 __user *)arg);
410 break;
411 case SPI_IOC_RD_LSB_FIRST:
412 retval = __put_user((spi->mode & SPI_LSB_FIRST) ? 1 : 0,
413 (__u8 __user *)arg);
414 break;
415 case SPI_IOC_RD_BITS_PER_WORD:
416 retval = __put_user(spi->bits_per_word, (__u8 __user *)arg);
417 break;
418 case SPI_IOC_RD_MAX_SPEED_HZ:
419 retval = __put_user(spidev->speed_hz, (__u32 __user *)arg);
420 break;
421
422 /* write requests */
423 case SPI_IOC_WR_MODE:
424 case SPI_IOC_WR_MODE32:
425 if (cmd == SPI_IOC_WR_MODE)
426 retval = __get_user(tmp, (u8 __user *)arg);
427 else
428 retval = __get_user(tmp, (u32 __user *)arg);
429 if (retval == 0) {
430 u32 save = spi->mode;
431
432 if (tmp & ~SPI_MODE_MASK) {
433 retval = -EINVAL;
434 break;
435 }
436
437 tmp |= spi->mode & ~SPI_MODE_MASK;
438 spi->mode = (u16)tmp;
439 retval = spi_setup(spi);
440 if (retval < 0)
441 spi->mode = save;
442 else
443 dev_dbg(&spi->dev, "spi mode %x\n", tmp);
444 }
445 break;
446 case SPI_IOC_WR_LSB_FIRST:
447 retval = __get_user(tmp, (__u8 __user *)arg);
448 if (retval == 0) {
449 u32 save = spi->mode;
450
451 if (tmp)
452 spi->mode |= SPI_LSB_FIRST;
453 else
454 spi->mode &= ~SPI_LSB_FIRST;
455 retval = spi_setup(spi);
456 if (retval < 0)
457 spi->mode = save;
458 else
459 dev_dbg(&spi->dev, "%csb first\n",
460 tmp ? 'l' : 'm');
461 }
462 break;
463 case SPI_IOC_WR_BITS_PER_WORD:
464 retval = __get_user(tmp, (__u8 __user *)arg);
465 if (retval == 0) {
466 u8 save = spi->bits_per_word;
467
468 spi->bits_per_word = tmp;
469 retval = spi_setup(spi);
470 if (retval < 0)
471 spi->bits_per_word = save;
472 else
473 dev_dbg(&spi->dev, "%d bits per word\n", tmp);
474 }
475 break;
476 case SPI_IOC_WR_MAX_SPEED_HZ:
477 retval = __get_user(tmp, (__u32 __user *)arg);
478 if (retval == 0) {
479 u32 save = spi->max_speed_hz;
480
481 spi->max_speed_hz = tmp;
482 retval = spi_setup(spi);
483 if (retval >= 0)
484 spidev->speed_hz = tmp;
485 else
486 dev_dbg(&spi->dev, "%d Hz (max)\n", tmp);
487 spi->max_speed_hz = save;
488 }
489 break;
490
491 default:
492 /* segmented and/or full-duplex I/O request */
493 /* Check message and copy into scratch area */
494 ioc = spidev_get_ioc_message(cmd,
495 (struct spi_ioc_transfer __user *)arg, &n_ioc);
496 if (IS_ERR(ioc)) {
497 retval = PTR_ERR(ioc);
498 break;
499 }
500 if (!ioc)
501 break; /* n_ioc is also 0 */
502
503 /* translate to spi_message, execute */
504 retval = spidev_message(spidev, ioc, n_ioc);
505 kfree(ioc);
506 break;
507 }
508
509 mutex_unlock(&spidev->buf_lock);
510 spi_dev_put(spi);
511 return retval;
512}
513
514#ifdef CONFIG_COMPAT
515static long
516spidev_compat_ioc_message(struct file *filp, unsigned int cmd,
517 unsigned long arg)
518{
519 struct spi_ioc_transfer __user *u_ioc;
520 int retval = 0;
521 struct spidev_data *spidev;
522 struct spi_device *spi;
523 unsigned n_ioc, n;
524 struct spi_ioc_transfer *ioc;
525
526 u_ioc = (struct spi_ioc_transfer __user *) compat_ptr(arg);
527 if (!access_ok(VERIFY_READ, u_ioc, _IOC_SIZE(cmd)))
528 return -EFAULT;
529
530 /* guard against device removal before, or while,
531 * we issue this ioctl.
532 */
533 spidev = filp->private_data;
534 spin_lock_irq(&spidev->spi_lock);
535 spi = spi_dev_get(spidev->spi);
536 spin_unlock_irq(&spidev->spi_lock);
537
538 if (spi == NULL)
539 return -ESHUTDOWN;
540
541 /* SPI_IOC_MESSAGE needs the buffer locked "normally" */
542 mutex_lock(&spidev->buf_lock);
543
544 /* Check message and copy into scratch area */
545 ioc = spidev_get_ioc_message(cmd, u_ioc, &n_ioc);
546 if (IS_ERR(ioc)) {
547 retval = PTR_ERR(ioc);
548 goto done;
549 }
550 if (!ioc)
551 goto done; /* n_ioc is also 0 */
552
553 /* Convert buffer pointers */
554 for (n = 0; n < n_ioc; n++) {
555 ioc[n].rx_buf = (uintptr_t) compat_ptr(ioc[n].rx_buf);
556 ioc[n].tx_buf = (uintptr_t) compat_ptr(ioc[n].tx_buf);
557 }
558
559 /* translate to spi_message, execute */
560 retval = spidev_message(spidev, ioc, n_ioc);
561 kfree(ioc);
562
563done:
564 mutex_unlock(&spidev->buf_lock);
565 spi_dev_put(spi);
566 return retval;
567}
568
569static long
570spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
571{
572 if (_IOC_TYPE(cmd) == SPI_IOC_MAGIC
573 && _IOC_NR(cmd) == _IOC_NR(SPI_IOC_MESSAGE(0))
574 && _IOC_DIR(cmd) == _IOC_WRITE)
575 return spidev_compat_ioc_message(filp, cmd, arg);
576
577 return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
578}
579#else
580#define spidev_compat_ioctl NULL
581#endif /* CONFIG_COMPAT */
582
583static int spidev_open(struct inode *inode, struct file *filp)
584{
585 struct spidev_data *spidev;
586 int status = -ENXIO;
587
588 mutex_lock(&device_list_lock);
589
590 list_for_each_entry(spidev, &device_list, device_entry) {
591 if (spidev->devt == inode->i_rdev) {
592 status = 0;
593 break;
594 }
595 }
596
597 if (status) {
598 pr_debug("spidev: nothing for minor %d\n", iminor(inode));
599 goto err_find_dev;
600 }
601
602 if (!spidev->tx_buffer) {
603 spidev->tx_buffer = kmalloc(bufsiz, GFP_KERNEL);
604 if (!spidev->tx_buffer) {
605 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
606 status = -ENOMEM;
607 goto err_find_dev;
608 }
609 }
610
611 if (!spidev->rx_buffer) {
612 spidev->rx_buffer = kmalloc(bufsiz, GFP_KERNEL);
613 if (!spidev->rx_buffer) {
614 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
615 status = -ENOMEM;
616 goto err_alloc_rx_buf;
617 }
618 }
619
620 spidev->users++;
621 filp->private_data = spidev;
622 nonseekable_open(inode, filp);
623
624 mutex_unlock(&device_list_lock);
625 return 0;
626
627err_alloc_rx_buf:
628 kfree(spidev->tx_buffer);
629 spidev->tx_buffer = NULL;
630err_find_dev:
631 mutex_unlock(&device_list_lock);
632 return status;
633}
634
635static int spidev_release(struct inode *inode, struct file *filp)
636{
637 struct spidev_data *spidev;
638
639 mutex_lock(&device_list_lock);
640 spidev = filp->private_data;
641 filp->private_data = NULL;
642
643 /* last close? */
644 spidev->users--;
645 if (!spidev->users) {
646 int dofree;
647
648 kfree(spidev->tx_buffer);
649 spidev->tx_buffer = NULL;
650
651 kfree(spidev->rx_buffer);
652 spidev->rx_buffer = NULL;
653
654 spin_lock_irq(&spidev->spi_lock);
655 if (spidev->spi)
656 spidev->speed_hz = spidev->spi->max_speed_hz;
657
658 /* ... after we unbound from the underlying device? */
659 dofree = (spidev->spi == NULL);
660 spin_unlock_irq(&spidev->spi_lock);
661
662 if (dofree)
663 kfree(spidev);
664 }
665 mutex_unlock(&device_list_lock);
666
667 return 0;
668}
669
670static const struct file_operations spidev_fops = {
671 .owner = THIS_MODULE,
672 /* REVISIT switch to aio primitives, so that userspace
673 * gets more complete API coverage. It'll simplify things
674 * too, except for the locking.
675 */
676 .write = spidev_write,
677 .read = spidev_read,
678 .unlocked_ioctl = spidev_ioctl,
679 .compat_ioctl = spidev_compat_ioctl,
680 .open = spidev_open,
681 .release = spidev_release,
682 .llseek = no_llseek,
683};
684
685/*-------------------------------------------------------------------------*/
686
687/* The main reason to have this class is to make mdev/udev create the
688 * /dev/spidevB.C character device nodes exposing our userspace API.
689 * It also simplifies memory management.
690 */
691
692static struct class *spidev_class;
693
694#ifdef CONFIG_OF
695static const struct of_device_id spidev_dt_ids[] = {
696 { .compatible = "rohm,dh2228fv" },
697 { .compatible = "lineartechnology,ltc2488" },
698 {},
699};
700MODULE_DEVICE_TABLE(of, spidev_dt_ids);
701#endif
702
703/*-------------------------------------------------------------------------*/
704
705static int spidev_probe(struct spi_device *spi)
706{
707 struct spidev_data *spidev;
708 int status;
709 unsigned long minor;
710
711 /*
712 * spidev should never be referenced in DT without a specific
713 * compatible string, it is a Linux implementation thing
714 * rather than a description of the hardware.
715 */
716 if (spi->dev.of_node && !of_match_device(spidev_dt_ids, &spi->dev)) {
717 dev_err(&spi->dev, "buggy DT: spidev listed directly in DT\n");
718 WARN_ON(spi->dev.of_node &&
719 !of_match_device(spidev_dt_ids, &spi->dev));
720 }
721
722 /* Allocate driver data */
723 spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);
724 if (!spidev)
725 return -ENOMEM;
726
727 /* Initialize the driver data */
728 spidev->spi = spi;
729 spin_lock_init(&spidev->spi_lock);
730 mutex_init(&spidev->buf_lock);
731
732 INIT_LIST_HEAD(&spidev->device_entry);
733
734 /* If we can allocate a minor number, hook up this device.
735 * Reusing minors is fine so long as udev or mdev is working.
736 */
737 mutex_lock(&device_list_lock);
738 minor = find_first_zero_bit(minors, N_SPI_MINORS);
739 if (minor < N_SPI_MINORS) {
740 struct device *dev;
741
742 spidev->devt = MKDEV(SPIDEV_MAJOR, minor);
743 dev = device_create(spidev_class, &spi->dev, spidev->devt,
744 spidev, "spidev%d.%d",
745 spi->master->bus_num, spi->chip_select);
746 status = PTR_ERR_OR_ZERO(dev);
747 } else {
748 dev_dbg(&spi->dev, "no minor number available!\n");
749 status = -ENODEV;
750 }
751 if (status == 0) {
752 set_bit(minor, minors);
753 list_add(&spidev->device_entry, &device_list);
754 }
755 mutex_unlock(&device_list_lock);
756
757 spidev->speed_hz = spi->max_speed_hz;
758
759 if (status == 0)
760 spi_set_drvdata(spi, spidev);
761 else
762 kfree(spidev);
763
764 return status;
765}
766
767static int spidev_remove(struct spi_device *spi)
768{
769 struct spidev_data *spidev = spi_get_drvdata(spi);
770
771 /* make sure ops on existing fds can abort cleanly */
772 spin_lock_irq(&spidev->spi_lock);
773 spidev->spi = NULL;
774 spin_unlock_irq(&spidev->spi_lock);
775
776 /* prevent new opens */
777 mutex_lock(&device_list_lock);
778 list_del(&spidev->device_entry);
779 device_destroy(spidev_class, spidev->devt);
780 clear_bit(MINOR(spidev->devt), minors);
781 if (spidev->users == 0)
782 kfree(spidev);
783 mutex_unlock(&device_list_lock);
784
785 return 0;
786}
787
788static struct spi_driver spidev_spi_driver = {
789 .driver = {
790 .name = "spidev",
791 .of_match_table = of_match_ptr(spidev_dt_ids),
792 },
793 .probe = spidev_probe,
794 .remove = spidev_remove,
795
796 /* NOTE: suspend/resume methods are not necessary here.
797 * We don't do anything except pass the requests to/from
798 * the underlying controller. The refrigerator handles
799 * most issues; the controller driver handles the rest.
800 */
801};
802
803/*-------------------------------------------------------------------------*/
804
805static int __init spidev_init(void)
806{
807 int status;
808
809 /* Claim our 256 reserved device numbers. Then register a class
810 * that will key udev/mdev to add/remove /dev nodes. Last, register
811 * the driver which manages those device numbers.
812 */
813 BUILD_BUG_ON(N_SPI_MINORS > 256);
814 status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);
815 if (status < 0)
816 return status;
817
818 spidev_class = class_create(THIS_MODULE, "spidev");
819 if (IS_ERR(spidev_class)) {
820 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
821 return PTR_ERR(spidev_class);
822 }
823
824 status = spi_register_driver(&spidev_spi_driver);
825 if (status < 0) {
826 class_destroy(spidev_class);
827 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
828 }
829 return status;
830}
831module_init(spidev_init);
832
833static void __exit spidev_exit(void)
834{
835 spi_unregister_driver(&spidev_spi_driver);
836 class_destroy(spidev_class);
837 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
838}
839module_exit(spidev_exit);
840
841MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>");
842MODULE_DESCRIPTION("User mode SPI device interface");
843MODULE_LICENSE("GPL");
844MODULE_ALIAS("spi:spidev");
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Simple synchronous userspace interface to SPI devices
4 *
5 * Copyright (C) 2006 SWAPP
6 * Andrea Paterniani <a.paterniani@swapp-eng.it>
7 * Copyright (C) 2007 David Brownell (simplification, cleanup)
8 */
9
10#include <linux/init.h>
11#include <linux/ioctl.h>
12#include <linux/fs.h>
13#include <linux/device.h>
14#include <linux/err.h>
15#include <linux/list.h>
16#include <linux/errno.h>
17#include <linux/mod_devicetable.h>
18#include <linux/module.h>
19#include <linux/mutex.h>
20#include <linux/property.h>
21#include <linux/slab.h>
22#include <linux/compat.h>
23
24#include <linux/spi/spi.h>
25#include <linux/spi/spidev.h>
26
27#include <linux/uaccess.h>
28
29
30/*
31 * This supports access to SPI devices using normal userspace I/O calls.
32 * Note that while traditional UNIX/POSIX I/O semantics are half duplex,
33 * and often mask message boundaries, full SPI support requires full duplex
34 * transfers. There are several kinds of internal message boundaries to
35 * handle chipselect management and other protocol options.
36 *
37 * SPI has a character major number assigned. We allocate minor numbers
38 * dynamically using a bitmask. You must use hotplug tools, such as udev
39 * (or mdev with busybox) to create and destroy the /dev/spidevB.C device
40 * nodes, since there is no fixed association of minor numbers with any
41 * particular SPI bus or device.
42 */
43#define SPIDEV_MAJOR 153 /* assigned */
44#define N_SPI_MINORS 32 /* ... up to 256 */
45
46static DECLARE_BITMAP(minors, N_SPI_MINORS);
47
48static_assert(N_SPI_MINORS > 0 && N_SPI_MINORS <= 256);
49
50/* Bit masks for spi_device.mode management. Note that incorrect
51 * settings for some settings can cause *lots* of trouble for other
52 * devices on a shared bus:
53 *
54 * - CS_HIGH ... this device will be active when it shouldn't be
55 * - 3WIRE ... when active, it won't behave as it should
56 * - NO_CS ... there will be no explicit message boundaries; this
57 * is completely incompatible with the shared bus model
58 * - READY ... transfers may proceed when they shouldn't.
59 *
60 * REVISIT should changing those flags be privileged?
61 */
62#define SPI_MODE_MASK (SPI_MODE_X_MASK | SPI_CS_HIGH \
63 | SPI_LSB_FIRST | SPI_3WIRE | SPI_LOOP \
64 | SPI_NO_CS | SPI_READY | SPI_TX_DUAL \
65 | SPI_TX_QUAD | SPI_TX_OCTAL | SPI_RX_DUAL \
66 | SPI_RX_QUAD | SPI_RX_OCTAL \
67 | SPI_RX_CPHA_FLIP | SPI_3WIRE_HIZ \
68 | SPI_MOSI_IDLE_LOW)
69
70struct spidev_data {
71 dev_t devt;
72 struct mutex spi_lock;
73 struct spi_device *spi;
74 struct list_head device_entry;
75
76 /* TX/RX buffers are NULL unless this device is open (users > 0) */
77 struct mutex buf_lock;
78 unsigned users;
79 u8 *tx_buffer;
80 u8 *rx_buffer;
81 u32 speed_hz;
82};
83
84static LIST_HEAD(device_list);
85static DEFINE_MUTEX(device_list_lock);
86
87static unsigned bufsiz = 4096;
88module_param(bufsiz, uint, S_IRUGO);
89MODULE_PARM_DESC(bufsiz, "data bytes in biggest supported SPI message");
90
91/*-------------------------------------------------------------------------*/
92
93static ssize_t
94spidev_sync_unlocked(struct spi_device *spi, struct spi_message *message)
95{
96 ssize_t status;
97
98 status = spi_sync(spi, message);
99 if (status == 0)
100 status = message->actual_length;
101
102 return status;
103}
104
105static ssize_t
106spidev_sync(struct spidev_data *spidev, struct spi_message *message)
107{
108 ssize_t status;
109 struct spi_device *spi;
110
111 mutex_lock(&spidev->spi_lock);
112 spi = spidev->spi;
113
114 if (spi == NULL)
115 status = -ESHUTDOWN;
116 else
117 status = spidev_sync_unlocked(spi, message);
118
119 mutex_unlock(&spidev->spi_lock);
120 return status;
121}
122
123static inline ssize_t
124spidev_sync_write(struct spidev_data *spidev, size_t len)
125{
126 struct spi_transfer t = {
127 .tx_buf = spidev->tx_buffer,
128 .len = len,
129 .speed_hz = spidev->speed_hz,
130 };
131 struct spi_message m;
132
133 spi_message_init(&m);
134 spi_message_add_tail(&t, &m);
135 return spidev_sync(spidev, &m);
136}
137
138static inline ssize_t
139spidev_sync_read(struct spidev_data *spidev, size_t len)
140{
141 struct spi_transfer t = {
142 .rx_buf = spidev->rx_buffer,
143 .len = len,
144 .speed_hz = spidev->speed_hz,
145 };
146 struct spi_message m;
147
148 spi_message_init(&m);
149 spi_message_add_tail(&t, &m);
150 return spidev_sync(spidev, &m);
151}
152
153/*-------------------------------------------------------------------------*/
154
155/* Read-only message with current device setup */
156static ssize_t
157spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
158{
159 struct spidev_data *spidev;
160 ssize_t status;
161
162 /* chipselect only toggles at start or end of operation */
163 if (count > bufsiz)
164 return -EMSGSIZE;
165
166 spidev = filp->private_data;
167
168 mutex_lock(&spidev->buf_lock);
169 status = spidev_sync_read(spidev, count);
170 if (status > 0) {
171 unsigned long missing;
172
173 missing = copy_to_user(buf, spidev->rx_buffer, status);
174 if (missing == status)
175 status = -EFAULT;
176 else
177 status = status - missing;
178 }
179 mutex_unlock(&spidev->buf_lock);
180
181 return status;
182}
183
184/* Write-only message with current device setup */
185static ssize_t
186spidev_write(struct file *filp, const char __user *buf,
187 size_t count, loff_t *f_pos)
188{
189 struct spidev_data *spidev;
190 ssize_t status;
191 unsigned long missing;
192
193 /* chipselect only toggles at start or end of operation */
194 if (count > bufsiz)
195 return -EMSGSIZE;
196
197 spidev = filp->private_data;
198
199 mutex_lock(&spidev->buf_lock);
200 missing = copy_from_user(spidev->tx_buffer, buf, count);
201 if (missing == 0)
202 status = spidev_sync_write(spidev, count);
203 else
204 status = -EFAULT;
205 mutex_unlock(&spidev->buf_lock);
206
207 return status;
208}
209
210static int spidev_message(struct spidev_data *spidev,
211 struct spi_ioc_transfer *u_xfers, unsigned n_xfers)
212{
213 struct spi_message msg;
214 struct spi_transfer *k_xfers;
215 struct spi_transfer *k_tmp;
216 struct spi_ioc_transfer *u_tmp;
217 unsigned n, total, tx_total, rx_total;
218 u8 *tx_buf, *rx_buf;
219 int status = -EFAULT;
220
221 spi_message_init(&msg);
222 k_xfers = kcalloc(n_xfers, sizeof(*k_tmp), GFP_KERNEL);
223 if (k_xfers == NULL)
224 return -ENOMEM;
225
226 /* Construct spi_message, copying any tx data to bounce buffer.
227 * We walk the array of user-provided transfers, using each one
228 * to initialize a kernel version of the same transfer.
229 */
230 tx_buf = spidev->tx_buffer;
231 rx_buf = spidev->rx_buffer;
232 total = 0;
233 tx_total = 0;
234 rx_total = 0;
235 for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers;
236 n;
237 n--, k_tmp++, u_tmp++) {
238 /* Ensure that also following allocations from rx_buf/tx_buf will meet
239 * DMA alignment requirements.
240 */
241 unsigned int len_aligned = ALIGN(u_tmp->len, ARCH_DMA_MINALIGN);
242
243 k_tmp->len = u_tmp->len;
244
245 total += k_tmp->len;
246 /* Since the function returns the total length of transfers
247 * on success, restrict the total to positive int values to
248 * avoid the return value looking like an error. Also check
249 * each transfer length to avoid arithmetic overflow.
250 */
251 if (total > INT_MAX || k_tmp->len > INT_MAX) {
252 status = -EMSGSIZE;
253 goto done;
254 }
255
256 if (u_tmp->rx_buf) {
257 /* this transfer needs space in RX bounce buffer */
258 rx_total += len_aligned;
259 if (rx_total > bufsiz) {
260 status = -EMSGSIZE;
261 goto done;
262 }
263 k_tmp->rx_buf = rx_buf;
264 rx_buf += len_aligned;
265 }
266 if (u_tmp->tx_buf) {
267 /* this transfer needs space in TX bounce buffer */
268 tx_total += len_aligned;
269 if (tx_total > bufsiz) {
270 status = -EMSGSIZE;
271 goto done;
272 }
273 k_tmp->tx_buf = tx_buf;
274 if (copy_from_user(tx_buf, (const u8 __user *)
275 (uintptr_t) u_tmp->tx_buf,
276 u_tmp->len))
277 goto done;
278 tx_buf += len_aligned;
279 }
280
281 k_tmp->cs_change = !!u_tmp->cs_change;
282 k_tmp->tx_nbits = u_tmp->tx_nbits;
283 k_tmp->rx_nbits = u_tmp->rx_nbits;
284 k_tmp->bits_per_word = u_tmp->bits_per_word;
285 k_tmp->delay.value = u_tmp->delay_usecs;
286 k_tmp->delay.unit = SPI_DELAY_UNIT_USECS;
287 k_tmp->speed_hz = u_tmp->speed_hz;
288 k_tmp->word_delay.value = u_tmp->word_delay_usecs;
289 k_tmp->word_delay.unit = SPI_DELAY_UNIT_USECS;
290 if (!k_tmp->speed_hz)
291 k_tmp->speed_hz = spidev->speed_hz;
292#ifdef VERBOSE
293 dev_dbg(&spidev->spi->dev,
294 " xfer len %u %s%s%s%dbits %u usec %u usec %uHz\n",
295 k_tmp->len,
296 k_tmp->rx_buf ? "rx " : "",
297 k_tmp->tx_buf ? "tx " : "",
298 k_tmp->cs_change ? "cs " : "",
299 k_tmp->bits_per_word ? : spidev->spi->bits_per_word,
300 k_tmp->delay.value,
301 k_tmp->word_delay.value,
302 k_tmp->speed_hz ? : spidev->spi->max_speed_hz);
303#endif
304 spi_message_add_tail(k_tmp, &msg);
305 }
306
307 status = spidev_sync_unlocked(spidev->spi, &msg);
308 if (status < 0)
309 goto done;
310
311 /* copy any rx data out of bounce buffer */
312 for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers;
313 n;
314 n--, k_tmp++, u_tmp++) {
315 if (u_tmp->rx_buf) {
316 if (copy_to_user((u8 __user *)
317 (uintptr_t) u_tmp->rx_buf, k_tmp->rx_buf,
318 u_tmp->len)) {
319 status = -EFAULT;
320 goto done;
321 }
322 }
323 }
324 status = total;
325
326done:
327 kfree(k_xfers);
328 return status;
329}
330
331static struct spi_ioc_transfer *
332spidev_get_ioc_message(unsigned int cmd, struct spi_ioc_transfer __user *u_ioc,
333 unsigned *n_ioc)
334{
335 u32 tmp;
336
337 /* Check type, command number and direction */
338 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC
339 || _IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0))
340 || _IOC_DIR(cmd) != _IOC_WRITE)
341 return ERR_PTR(-ENOTTY);
342
343 tmp = _IOC_SIZE(cmd);
344 if ((tmp % sizeof(struct spi_ioc_transfer)) != 0)
345 return ERR_PTR(-EINVAL);
346 *n_ioc = tmp / sizeof(struct spi_ioc_transfer);
347 if (*n_ioc == 0)
348 return NULL;
349
350 /* copy into scratch area */
351 return memdup_user(u_ioc, tmp);
352}
353
354static long
355spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
356{
357 int retval = 0;
358 struct spidev_data *spidev;
359 struct spi_device *spi;
360 struct spi_controller *ctlr;
361 u32 tmp;
362 unsigned n_ioc;
363 struct spi_ioc_transfer *ioc;
364
365 /* Check type and command number */
366 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC)
367 return -ENOTTY;
368
369 /* guard against device removal before, or while,
370 * we issue this ioctl.
371 */
372 spidev = filp->private_data;
373 mutex_lock(&spidev->spi_lock);
374 spi = spi_dev_get(spidev->spi);
375 if (spi == NULL) {
376 mutex_unlock(&spidev->spi_lock);
377 return -ESHUTDOWN;
378 }
379
380 ctlr = spi->controller;
381
382 /* use the buffer lock here for triple duty:
383 * - prevent I/O (from us) so calling spi_setup() is safe;
384 * - prevent concurrent SPI_IOC_WR_* from morphing
385 * data fields while SPI_IOC_RD_* reads them;
386 * - SPI_IOC_MESSAGE needs the buffer locked "normally".
387 */
388 mutex_lock(&spidev->buf_lock);
389
390 switch (cmd) {
391 /* read requests */
392 case SPI_IOC_RD_MODE:
393 case SPI_IOC_RD_MODE32:
394 tmp = spi->mode & SPI_MODE_MASK;
395
396 if (ctlr->use_gpio_descriptors && spi_get_csgpiod(spi, 0))
397 tmp &= ~SPI_CS_HIGH;
398
399 if (cmd == SPI_IOC_RD_MODE)
400 retval = put_user(tmp, (__u8 __user *)arg);
401 else
402 retval = put_user(tmp, (__u32 __user *)arg);
403 break;
404 case SPI_IOC_RD_LSB_FIRST:
405 retval = put_user((spi->mode & SPI_LSB_FIRST) ? 1 : 0,
406 (__u8 __user *)arg);
407 break;
408 case SPI_IOC_RD_BITS_PER_WORD:
409 retval = put_user(spi->bits_per_word, (__u8 __user *)arg);
410 break;
411 case SPI_IOC_RD_MAX_SPEED_HZ:
412 retval = put_user(spidev->speed_hz, (__u32 __user *)arg);
413 break;
414
415 /* write requests */
416 case SPI_IOC_WR_MODE:
417 case SPI_IOC_WR_MODE32:
418 if (cmd == SPI_IOC_WR_MODE)
419 retval = get_user(tmp, (u8 __user *)arg);
420 else
421 retval = get_user(tmp, (u32 __user *)arg);
422 if (retval == 0) {
423 u32 save = spi->mode;
424
425 if (tmp & ~SPI_MODE_MASK) {
426 retval = -EINVAL;
427 break;
428 }
429
430 if (ctlr->use_gpio_descriptors && spi_get_csgpiod(spi, 0))
431 tmp |= SPI_CS_HIGH;
432
433 tmp |= spi->mode & ~SPI_MODE_MASK;
434 spi->mode = tmp & SPI_MODE_USER_MASK;
435 retval = spi_setup(spi);
436 if (retval < 0)
437 spi->mode = save;
438 else
439 dev_dbg(&spi->dev, "spi mode %x\n", tmp);
440 }
441 break;
442 case SPI_IOC_WR_LSB_FIRST:
443 retval = get_user(tmp, (__u8 __user *)arg);
444 if (retval == 0) {
445 u32 save = spi->mode;
446
447 if (tmp)
448 spi->mode |= SPI_LSB_FIRST;
449 else
450 spi->mode &= ~SPI_LSB_FIRST;
451 retval = spi_setup(spi);
452 if (retval < 0)
453 spi->mode = save;
454 else
455 dev_dbg(&spi->dev, "%csb first\n",
456 tmp ? 'l' : 'm');
457 }
458 break;
459 case SPI_IOC_WR_BITS_PER_WORD:
460 retval = get_user(tmp, (__u8 __user *)arg);
461 if (retval == 0) {
462 u8 save = spi->bits_per_word;
463
464 spi->bits_per_word = tmp;
465 retval = spi_setup(spi);
466 if (retval < 0)
467 spi->bits_per_word = save;
468 else
469 dev_dbg(&spi->dev, "%d bits per word\n", tmp);
470 }
471 break;
472 case SPI_IOC_WR_MAX_SPEED_HZ: {
473 u32 save;
474
475 retval = get_user(tmp, (__u32 __user *)arg);
476 if (retval)
477 break;
478 if (tmp == 0) {
479 retval = -EINVAL;
480 break;
481 }
482
483 save = spi->max_speed_hz;
484
485 spi->max_speed_hz = tmp;
486 retval = spi_setup(spi);
487 if (retval == 0) {
488 spidev->speed_hz = tmp;
489 dev_dbg(&spi->dev, "%d Hz (max)\n", spidev->speed_hz);
490 }
491
492 spi->max_speed_hz = save;
493 break;
494 }
495 default:
496 /* segmented and/or full-duplex I/O request */
497 /* Check message and copy into scratch area */
498 ioc = spidev_get_ioc_message(cmd,
499 (struct spi_ioc_transfer __user *)arg, &n_ioc);
500 if (IS_ERR(ioc)) {
501 retval = PTR_ERR(ioc);
502 break;
503 }
504 if (!ioc)
505 break; /* n_ioc is also 0 */
506
507 /* translate to spi_message, execute */
508 retval = spidev_message(spidev, ioc, n_ioc);
509 kfree(ioc);
510 break;
511 }
512
513 mutex_unlock(&spidev->buf_lock);
514 spi_dev_put(spi);
515 mutex_unlock(&spidev->spi_lock);
516 return retval;
517}
518
519#ifdef CONFIG_COMPAT
520static long
521spidev_compat_ioc_message(struct file *filp, unsigned int cmd,
522 unsigned long arg)
523{
524 struct spi_ioc_transfer __user *u_ioc;
525 int retval = 0;
526 struct spidev_data *spidev;
527 struct spi_device *spi;
528 unsigned n_ioc, n;
529 struct spi_ioc_transfer *ioc;
530
531 u_ioc = (struct spi_ioc_transfer __user *) compat_ptr(arg);
532
533 /* guard against device removal before, or while,
534 * we issue this ioctl.
535 */
536 spidev = filp->private_data;
537 mutex_lock(&spidev->spi_lock);
538 spi = spi_dev_get(spidev->spi);
539 if (spi == NULL) {
540 mutex_unlock(&spidev->spi_lock);
541 return -ESHUTDOWN;
542 }
543
544 /* SPI_IOC_MESSAGE needs the buffer locked "normally" */
545 mutex_lock(&spidev->buf_lock);
546
547 /* Check message and copy into scratch area */
548 ioc = spidev_get_ioc_message(cmd, u_ioc, &n_ioc);
549 if (IS_ERR(ioc)) {
550 retval = PTR_ERR(ioc);
551 goto done;
552 }
553 if (!ioc)
554 goto done; /* n_ioc is also 0 */
555
556 /* Convert buffer pointers */
557 for (n = 0; n < n_ioc; n++) {
558 ioc[n].rx_buf = (uintptr_t) compat_ptr(ioc[n].rx_buf);
559 ioc[n].tx_buf = (uintptr_t) compat_ptr(ioc[n].tx_buf);
560 }
561
562 /* translate to spi_message, execute */
563 retval = spidev_message(spidev, ioc, n_ioc);
564 kfree(ioc);
565
566done:
567 mutex_unlock(&spidev->buf_lock);
568 spi_dev_put(spi);
569 mutex_unlock(&spidev->spi_lock);
570 return retval;
571}
572
573static long
574spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
575{
576 if (_IOC_TYPE(cmd) == SPI_IOC_MAGIC
577 && _IOC_NR(cmd) == _IOC_NR(SPI_IOC_MESSAGE(0))
578 && _IOC_DIR(cmd) == _IOC_WRITE)
579 return spidev_compat_ioc_message(filp, cmd, arg);
580
581 return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
582}
583#else
584#define spidev_compat_ioctl NULL
585#endif /* CONFIG_COMPAT */
586
587static int spidev_open(struct inode *inode, struct file *filp)
588{
589 struct spidev_data *spidev = NULL, *iter;
590 int status = -ENXIO;
591
592 mutex_lock(&device_list_lock);
593
594 list_for_each_entry(iter, &device_list, device_entry) {
595 if (iter->devt == inode->i_rdev) {
596 status = 0;
597 spidev = iter;
598 break;
599 }
600 }
601
602 if (!spidev) {
603 pr_debug("spidev: nothing for minor %d\n", iminor(inode));
604 goto err_find_dev;
605 }
606
607 if (!spidev->tx_buffer) {
608 spidev->tx_buffer = kmalloc(bufsiz, GFP_KERNEL);
609 if (!spidev->tx_buffer) {
610 status = -ENOMEM;
611 goto err_find_dev;
612 }
613 }
614
615 if (!spidev->rx_buffer) {
616 spidev->rx_buffer = kmalloc(bufsiz, GFP_KERNEL);
617 if (!spidev->rx_buffer) {
618 status = -ENOMEM;
619 goto err_alloc_rx_buf;
620 }
621 }
622
623 spidev->users++;
624 filp->private_data = spidev;
625 stream_open(inode, filp);
626
627 mutex_unlock(&device_list_lock);
628 return 0;
629
630err_alloc_rx_buf:
631 kfree(spidev->tx_buffer);
632 spidev->tx_buffer = NULL;
633err_find_dev:
634 mutex_unlock(&device_list_lock);
635 return status;
636}
637
638static int spidev_release(struct inode *inode, struct file *filp)
639{
640 struct spidev_data *spidev;
641 int dofree;
642
643 mutex_lock(&device_list_lock);
644 spidev = filp->private_data;
645 filp->private_data = NULL;
646
647 mutex_lock(&spidev->spi_lock);
648 /* ... after we unbound from the underlying device? */
649 dofree = (spidev->spi == NULL);
650 mutex_unlock(&spidev->spi_lock);
651
652 /* last close? */
653 spidev->users--;
654 if (!spidev->users) {
655
656 kfree(spidev->tx_buffer);
657 spidev->tx_buffer = NULL;
658
659 kfree(spidev->rx_buffer);
660 spidev->rx_buffer = NULL;
661
662 if (dofree)
663 kfree(spidev);
664 else
665 spidev->speed_hz = spidev->spi->max_speed_hz;
666 }
667#ifdef CONFIG_SPI_SLAVE
668 if (!dofree)
669 spi_target_abort(spidev->spi);
670#endif
671 mutex_unlock(&device_list_lock);
672
673 return 0;
674}
675
676static const struct file_operations spidev_fops = {
677 .owner = THIS_MODULE,
678 /* REVISIT switch to aio primitives, so that userspace
679 * gets more complete API coverage. It'll simplify things
680 * too, except for the locking.
681 */
682 .write = spidev_write,
683 .read = spidev_read,
684 .unlocked_ioctl = spidev_ioctl,
685 .compat_ioctl = spidev_compat_ioctl,
686 .open = spidev_open,
687 .release = spidev_release,
688};
689
690/*-------------------------------------------------------------------------*/
691
692/* The main reason to have this class is to make mdev/udev create the
693 * /dev/spidevB.C character device nodes exposing our userspace API.
694 * It also simplifies memory management.
695 */
696
697static const struct class spidev_class = {
698 .name = "spidev",
699};
700
701static const struct spi_device_id spidev_spi_ids[] = {
702 { .name = "bh2228fv" },
703 { .name = "dh2228fv" },
704 { .name = "jg10309-01" },
705 { .name = "ltc2488" },
706 { .name = "sx1301" },
707 { .name = "bk4" },
708 { .name = "dhcom-board" },
709 { .name = "m53cpld" },
710 { .name = "spi-petra" },
711 { .name = "spi-authenta" },
712 { .name = "em3581" },
713 { .name = "si3210" },
714 {},
715};
716MODULE_DEVICE_TABLE(spi, spidev_spi_ids);
717
718/*
719 * spidev should never be referenced in DT without a specific compatible string,
720 * it is a Linux implementation thing rather than a description of the hardware.
721 */
722static int spidev_of_check(struct device *dev)
723{
724 if (device_property_match_string(dev, "compatible", "spidev") < 0)
725 return 0;
726
727 dev_err(dev, "spidev listed directly in DT is not supported\n");
728 return -EINVAL;
729}
730
731static const struct of_device_id spidev_dt_ids[] = {
732 { .compatible = "cisco,spi-petra", .data = &spidev_of_check },
733 { .compatible = "dh,dhcom-board", .data = &spidev_of_check },
734 { .compatible = "elgin,jg10309-01", .data = &spidev_of_check },
735 { .compatible = "lineartechnology,ltc2488", .data = &spidev_of_check },
736 { .compatible = "lwn,bk4", .data = &spidev_of_check },
737 { .compatible = "menlo,m53cpld", .data = &spidev_of_check },
738 { .compatible = "micron,spi-authenta", .data = &spidev_of_check },
739 { .compatible = "rohm,bh2228fv", .data = &spidev_of_check },
740 { .compatible = "rohm,dh2228fv", .data = &spidev_of_check },
741 { .compatible = "semtech,sx1301", .data = &spidev_of_check },
742 { .compatible = "silabs,em3581", .data = &spidev_of_check },
743 { .compatible = "silabs,si3210", .data = &spidev_of_check },
744 {},
745};
746MODULE_DEVICE_TABLE(of, spidev_dt_ids);
747
748/* Dummy SPI devices not to be used in production systems */
749static int spidev_acpi_check(struct device *dev)
750{
751 dev_warn(dev, "do not use this driver in production systems!\n");
752 return 0;
753}
754
755static const struct acpi_device_id spidev_acpi_ids[] = {
756 /*
757 * The ACPI SPT000* devices are only meant for development and
758 * testing. Systems used in production should have a proper ACPI
759 * description of the connected peripheral and they should also use
760 * a proper driver instead of poking directly to the SPI bus.
761 */
762 { "SPT0001", (kernel_ulong_t)&spidev_acpi_check },
763 { "SPT0002", (kernel_ulong_t)&spidev_acpi_check },
764 { "SPT0003", (kernel_ulong_t)&spidev_acpi_check },
765 {},
766};
767MODULE_DEVICE_TABLE(acpi, spidev_acpi_ids);
768
769/*-------------------------------------------------------------------------*/
770
771static int spidev_probe(struct spi_device *spi)
772{
773 int (*match)(struct device *dev);
774 struct spidev_data *spidev;
775 int status;
776 unsigned long minor;
777
778 match = device_get_match_data(&spi->dev);
779 if (match) {
780 status = match(&spi->dev);
781 if (status)
782 return status;
783 }
784
785 /* Allocate driver data */
786 spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);
787 if (!spidev)
788 return -ENOMEM;
789
790 /* Initialize the driver data */
791 spidev->spi = spi;
792 mutex_init(&spidev->spi_lock);
793 mutex_init(&spidev->buf_lock);
794
795 INIT_LIST_HEAD(&spidev->device_entry);
796
797 /* If we can allocate a minor number, hook up this device.
798 * Reusing minors is fine so long as udev or mdev is working.
799 */
800 mutex_lock(&device_list_lock);
801 minor = find_first_zero_bit(minors, N_SPI_MINORS);
802 if (minor < N_SPI_MINORS) {
803 struct device *dev;
804
805 spidev->devt = MKDEV(SPIDEV_MAJOR, minor);
806 dev = device_create(&spidev_class, &spi->dev, spidev->devt,
807 spidev, "spidev%d.%d",
808 spi->controller->bus_num, spi_get_chipselect(spi, 0));
809 status = PTR_ERR_OR_ZERO(dev);
810 } else {
811 dev_dbg(&spi->dev, "no minor number available!\n");
812 status = -ENODEV;
813 }
814 if (status == 0) {
815 set_bit(minor, minors);
816 list_add(&spidev->device_entry, &device_list);
817 }
818 mutex_unlock(&device_list_lock);
819
820 spidev->speed_hz = spi->max_speed_hz;
821
822 if (status == 0)
823 spi_set_drvdata(spi, spidev);
824 else
825 kfree(spidev);
826
827 return status;
828}
829
830static void spidev_remove(struct spi_device *spi)
831{
832 struct spidev_data *spidev = spi_get_drvdata(spi);
833
834 /* prevent new opens */
835 mutex_lock(&device_list_lock);
836 /* make sure ops on existing fds can abort cleanly */
837 mutex_lock(&spidev->spi_lock);
838 spidev->spi = NULL;
839 mutex_unlock(&spidev->spi_lock);
840
841 list_del(&spidev->device_entry);
842 device_destroy(&spidev_class, spidev->devt);
843 clear_bit(MINOR(spidev->devt), minors);
844 if (spidev->users == 0)
845 kfree(spidev);
846 mutex_unlock(&device_list_lock);
847}
848
849static struct spi_driver spidev_spi_driver = {
850 .driver = {
851 .name = "spidev",
852 .of_match_table = spidev_dt_ids,
853 .acpi_match_table = spidev_acpi_ids,
854 },
855 .probe = spidev_probe,
856 .remove = spidev_remove,
857 .id_table = spidev_spi_ids,
858
859 /* NOTE: suspend/resume methods are not necessary here.
860 * We don't do anything except pass the requests to/from
861 * the underlying controller. The refrigerator handles
862 * most issues; the controller driver handles the rest.
863 */
864};
865
866/*-------------------------------------------------------------------------*/
867
868static int __init spidev_init(void)
869{
870 int status;
871
872 /* Claim our 256 reserved device numbers. Then register a class
873 * that will key udev/mdev to add/remove /dev nodes. Last, register
874 * the driver which manages those device numbers.
875 */
876 status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);
877 if (status < 0)
878 return status;
879
880 status = class_register(&spidev_class);
881 if (status) {
882 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
883 return status;
884 }
885
886 status = spi_register_driver(&spidev_spi_driver);
887 if (status < 0) {
888 class_unregister(&spidev_class);
889 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
890 }
891 return status;
892}
893module_init(spidev_init);
894
895static void __exit spidev_exit(void)
896{
897 spi_unregister_driver(&spidev_spi_driver);
898 class_unregister(&spidev_class);
899 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
900}
901module_exit(spidev_exit);
902
903MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>");
904MODULE_DESCRIPTION("User mode SPI device interface");
905MODULE_LICENSE("GPL");
906MODULE_ALIAS("spi:spidev");