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