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