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
46 static DECLARE_BITMAP(minors, N_SPI_MINORS);
47
48 static_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
70 struct 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
84 static LIST_HEAD(device_list);
85 static DEFINE_MUTEX(device_list_lock);
86
87 static unsigned bufsiz = 4096;
88 module_param(bufsiz, uint, S_IRUGO);
89 MODULE_PARM_DESC(bufsiz, "data bytes in biggest supported SPI message");
90
91 /*-------------------------------------------------------------------------*/
92
93 static ssize_t
spidev_sync_unlocked(struct spi_device * spi,struct spi_message * message)94 spidev_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
105 static ssize_t
spidev_sync(struct spidev_data * spidev,struct spi_message * message)106 spidev_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
123 static inline ssize_t
spidev_sync_write(struct spidev_data * spidev,size_t len)124 spidev_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
138 static inline ssize_t
spidev_sync_read(struct spidev_data * spidev,size_t len)139 spidev_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 */
156 static ssize_t
spidev_read(struct file * filp,char __user * buf,size_t count,loff_t * f_pos)157 spidev_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 */
185 static ssize_t
spidev_write(struct file * filp,const char __user * buf,size_t count,loff_t * f_pos)186 spidev_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
spidev_message(struct spidev_data * spidev,struct spi_ioc_transfer * u_xfers,unsigned n_xfers)210 static 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
326 done:
327 kfree(k_xfers);
328 return status;
329 }
330
331 static struct spi_ioc_transfer *
spidev_get_ioc_message(unsigned int cmd,struct spi_ioc_transfer __user * u_ioc,unsigned * n_ioc)332 spidev_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
354 static long
spidev_ioctl(struct file * filp,unsigned int cmd,unsigned long arg)355 spidev_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_get_chipselect(spi, 0)])
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_get_chipselect(spi, 0)])
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
526 static long
spidev_compat_ioc_message(struct file * filp,unsigned int cmd,unsigned long arg)527 spidev_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
572 done:
573 mutex_unlock(&spidev->buf_lock);
574 spi_dev_put(spi);
575 mutex_unlock(&spidev->spi_lock);
576 return retval;
577 }
578
579 static long
spidev_compat_ioctl(struct file * filp,unsigned int cmd,unsigned long arg)580 spidev_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
spidev_open(struct inode * inode,struct file * filp)593 static 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
636 err_alloc_rx_buf:
637 kfree(spidev->tx_buffer);
638 spidev->tx_buffer = NULL;
639 err_find_dev:
640 mutex_unlock(&device_list_lock);
641 return status;
642 }
643
spidev_release(struct inode * inode,struct file * filp)644 static 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
682 static 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
704 static struct class *spidev_class;
705
706 static 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 { .name = "em3581" },
716 { .name = "si3210" },
717 {},
718 };
719 MODULE_DEVICE_TABLE(spi, spidev_spi_ids);
720
721 /*
722 * spidev should never be referenced in DT without a specific compatible string,
723 * it is a Linux implementation thing rather than a description of the hardware.
724 */
spidev_of_check(struct device * dev)725 static int spidev_of_check(struct device *dev)
726 {
727 if (device_property_match_string(dev, "compatible", "spidev") < 0)
728 return 0;
729
730 dev_err(dev, "spidev listed directly in DT is not supported\n");
731 return -EINVAL;
732 }
733
734 static const struct of_device_id spidev_dt_ids[] = {
735 { .compatible = "cisco,spi-petra", .data = &spidev_of_check },
736 { .compatible = "dh,dhcom-board", .data = &spidev_of_check },
737 { .compatible = "lineartechnology,ltc2488", .data = &spidev_of_check },
738 { .compatible = "lwn,bk4", .data = &spidev_of_check },
739 { .compatible = "menlo,m53cpld", .data = &spidev_of_check },
740 { .compatible = "micron,spi-authenta", .data = &spidev_of_check },
741 { .compatible = "rohm,dh2228fv", .data = &spidev_of_check },
742 { .compatible = "semtech,sx1301", .data = &spidev_of_check },
743 { .compatible = "silabs,em3581", .data = &spidev_of_check },
744 { .compatible = "silabs,si3210", .data = &spidev_of_check },
745 {},
746 };
747 MODULE_DEVICE_TABLE(of, spidev_dt_ids);
748
749 /* Dummy SPI devices not to be used in production systems */
spidev_acpi_check(struct device * dev)750 static int spidev_acpi_check(struct device *dev)
751 {
752 dev_warn(dev, "do not use this driver in production systems!\n");
753 return 0;
754 }
755
756 static const struct acpi_device_id spidev_acpi_ids[] = {
757 /*
758 * The ACPI SPT000* devices are only meant for development and
759 * testing. Systems used in production should have a proper ACPI
760 * description of the connected peripheral and they should also use
761 * a proper driver instead of poking directly to the SPI bus.
762 */
763 { "SPT0001", (kernel_ulong_t)&spidev_acpi_check },
764 { "SPT0002", (kernel_ulong_t)&spidev_acpi_check },
765 { "SPT0003", (kernel_ulong_t)&spidev_acpi_check },
766 {},
767 };
768 MODULE_DEVICE_TABLE(acpi, spidev_acpi_ids);
769
770 /*-------------------------------------------------------------------------*/
771
spidev_probe(struct spi_device * spi)772 static int spidev_probe(struct spi_device *spi)
773 {
774 int (*match)(struct device *dev);
775 struct spidev_data *spidev;
776 int status;
777 unsigned long minor;
778
779 match = device_get_match_data(&spi->dev);
780 if (match) {
781 status = match(&spi->dev);
782 if (status)
783 return status;
784 }
785
786 /* Allocate driver data */
787 spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);
788 if (!spidev)
789 return -ENOMEM;
790
791 /* Initialize the driver data */
792 spidev->spi = spi;
793 mutex_init(&spidev->spi_lock);
794 mutex_init(&spidev->buf_lock);
795
796 INIT_LIST_HEAD(&spidev->device_entry);
797
798 /* If we can allocate a minor number, hook up this device.
799 * Reusing minors is fine so long as udev or mdev is working.
800 */
801 mutex_lock(&device_list_lock);
802 minor = find_first_zero_bit(minors, N_SPI_MINORS);
803 if (minor < N_SPI_MINORS) {
804 struct device *dev;
805
806 spidev->devt = MKDEV(SPIDEV_MAJOR, minor);
807 dev = device_create(spidev_class, &spi->dev, spidev->devt,
808 spidev, "spidev%d.%d",
809 spi->master->bus_num, spi_get_chipselect(spi, 0));
810 status = PTR_ERR_OR_ZERO(dev);
811 } else {
812 dev_dbg(&spi->dev, "no minor number available!\n");
813 status = -ENODEV;
814 }
815 if (status == 0) {
816 set_bit(minor, minors);
817 list_add(&spidev->device_entry, &device_list);
818 }
819 mutex_unlock(&device_list_lock);
820
821 spidev->speed_hz = spi->max_speed_hz;
822
823 if (status == 0)
824 spi_set_drvdata(spi, spidev);
825 else
826 kfree(spidev);
827
828 return status;
829 }
830
spidev_remove(struct spi_device * spi)831 static void spidev_remove(struct spi_device *spi)
832 {
833 struct spidev_data *spidev = spi_get_drvdata(spi);
834
835 /* prevent new opens */
836 mutex_lock(&device_list_lock);
837 /* make sure ops on existing fds can abort cleanly */
838 mutex_lock(&spidev->spi_lock);
839 spidev->spi = NULL;
840 mutex_unlock(&spidev->spi_lock);
841
842 list_del(&spidev->device_entry);
843 device_destroy(spidev_class, spidev->devt);
844 clear_bit(MINOR(spidev->devt), minors);
845 if (spidev->users == 0)
846 kfree(spidev);
847 mutex_unlock(&device_list_lock);
848 }
849
850 static struct spi_driver spidev_spi_driver = {
851 .driver = {
852 .name = "spidev",
853 .of_match_table = spidev_dt_ids,
854 .acpi_match_table = spidev_acpi_ids,
855 },
856 .probe = spidev_probe,
857 .remove = spidev_remove,
858 .id_table = spidev_spi_ids,
859
860 /* NOTE: suspend/resume methods are not necessary here.
861 * We don't do anything except pass the requests to/from
862 * the underlying controller. The refrigerator handles
863 * most issues; the controller driver handles the rest.
864 */
865 };
866
867 /*-------------------------------------------------------------------------*/
868
spidev_init(void)869 static int __init spidev_init(void)
870 {
871 int status;
872
873 /* Claim our 256 reserved device numbers. Then register a class
874 * that will key udev/mdev to add/remove /dev nodes. Last, register
875 * the driver which manages those device numbers.
876 */
877 status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);
878 if (status < 0)
879 return status;
880
881 spidev_class = class_create("spidev");
882 if (IS_ERR(spidev_class)) {
883 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
884 return PTR_ERR(spidev_class);
885 }
886
887 status = spi_register_driver(&spidev_spi_driver);
888 if (status < 0) {
889 class_destroy(spidev_class);
890 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
891 }
892 return status;
893 }
894 module_init(spidev_init);
895
spidev_exit(void)896 static void __exit spidev_exit(void)
897 {
898 spi_unregister_driver(&spidev_spi_driver);
899 class_destroy(spidev_class);
900 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
901 }
902 module_exit(spidev_exit);
903
904 MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>");
905 MODULE_DESCRIPTION("User mode SPI device interface");
906 MODULE_LICENSE("GPL");
907 MODULE_ALIAS("spi:spidev");
908