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