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 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
520 static long
spidev_compat_ioc_message(struct file * filp,unsigned int cmd,unsigned long arg)521 spidev_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
566 done:
567 mutex_unlock(&spidev->buf_lock);
568 spi_dev_put(spi);
569 mutex_unlock(&spidev->spi_lock);
570 return retval;
571 }
572
573 static long
spidev_compat_ioctl(struct file * filp,unsigned int cmd,unsigned long arg)574 spidev_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
spidev_open(struct inode * inode,struct file * filp)587 static 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
630 err_alloc_rx_buf:
631 kfree(spidev->tx_buffer);
632 spidev->tx_buffer = NULL;
633 err_find_dev:
634 mutex_unlock(&device_list_lock);
635 return status;
636 }
637
spidev_release(struct inode * inode,struct file * filp)638 static 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
676 static 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
697 static const struct class spidev_class = {
698 .name = "spidev",
699 };
700
701 static 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 };
716 MODULE_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 */
spidev_of_check(struct device * dev)722 static 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
731 static 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 };
746 MODULE_DEVICE_TABLE(of, spidev_dt_ids);
747
748 /* Dummy SPI devices not to be used in production systems */
spidev_acpi_check(struct device * dev)749 static 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
755 static 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 };
767 MODULE_DEVICE_TABLE(acpi, spidev_acpi_ids);
768
769 /*-------------------------------------------------------------------------*/
770
spidev_probe(struct spi_device * spi)771 static 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
spidev_remove(struct spi_device * spi)830 static 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
849 static 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
spidev_init(void)868 static 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 }
893 module_init(spidev_init);
894
spidev_exit(void)895 static 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 }
901 module_exit(spidev_exit);
902
903 MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>");
904 MODULE_DESCRIPTION("User mode SPI device interface");
905 MODULE_LICENSE("GPL");
906 MODULE_ALIAS("spi:spidev");
907