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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
56static 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
76struct 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
90static LIST_HEAD(device_list);
91static DEFINE_MUTEX(device_list_lock);
92
93static unsigned bufsiz = 4096;
94module_param(bufsiz, uint, S_IRUGO);
95MODULE_PARM_DESC(bufsiz, "data bytes in biggest supported SPI message");
96
97/*-------------------------------------------------------------------------*/
98
99static ssize_t
100spidev_sync(struct spidev_data *spidev, struct spi_message *message)
101{
102 DECLARE_COMPLETION_ONSTACK(done);
103 int status;
104 struct spi_device *spi;
105
106 spin_lock_irq(&spidev->spi_lock);
107 spi = spidev->spi;
108 spin_unlock_irq(&spidev->spi_lock);
109
110 if (spi == NULL)
111 status = -ESHUTDOWN;
112 else
113 status = spi_sync(spi, message);
114
115 if (status == 0)
116 status = message->actual_length;
117
118 return status;
119}
120
121static inline ssize_t
122spidev_sync_write(struct spidev_data *spidev, size_t len)
123{
124 struct spi_transfer t = {
125 .tx_buf = spidev->tx_buffer,
126 .len = len,
127 .speed_hz = spidev->speed_hz,
128 };
129 struct spi_message m;
130
131 spi_message_init(&m);
132 spi_message_add_tail(&t, &m);
133 return spidev_sync(spidev, &m);
134}
135
136static inline ssize_t
137spidev_sync_read(struct spidev_data *spidev, size_t len)
138{
139 struct spi_transfer t = {
140 .rx_buf = spidev->rx_buffer,
141 .len = len,
142 .speed_hz = spidev->speed_hz,
143 };
144 struct spi_message m;
145
146 spi_message_init(&m);
147 spi_message_add_tail(&t, &m);
148 return spidev_sync(spidev, &m);
149}
150
151/*-------------------------------------------------------------------------*/
152
153/* Read-only message with current device setup */
154static ssize_t
155spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
156{
157 struct spidev_data *spidev;
158 ssize_t status = 0;
159
160 /* chipselect only toggles at start or end of operation */
161 if (count > bufsiz)
162 return -EMSGSIZE;
163
164 spidev = filp->private_data;
165
166 mutex_lock(&spidev->buf_lock);
167 status = spidev_sync_read(spidev, count);
168 if (status > 0) {
169 unsigned long missing;
170
171 missing = copy_to_user(buf, spidev->rx_buffer, status);
172 if (missing == status)
173 status = -EFAULT;
174 else
175 status = status - missing;
176 }
177 mutex_unlock(&spidev->buf_lock);
178
179 return status;
180}
181
182/* Write-only message with current device setup */
183static ssize_t
184spidev_write(struct file *filp, const char __user *buf,
185 size_t count, loff_t *f_pos)
186{
187 struct spidev_data *spidev;
188 ssize_t status = 0;
189 unsigned long missing;
190
191 /* chipselect only toggles at start or end of operation */
192 if (count > bufsiz)
193 return -EMSGSIZE;
194
195 spidev = filp->private_data;
196
197 mutex_lock(&spidev->buf_lock);
198 missing = copy_from_user(spidev->tx_buffer, buf, count);
199 if (missing == 0)
200 status = spidev_sync_write(spidev, count);
201 else
202 status = -EFAULT;
203 mutex_unlock(&spidev->buf_lock);
204
205 return status;
206}
207
208static int spidev_message(struct spidev_data *spidev,
209 struct spi_ioc_transfer *u_xfers, unsigned n_xfers)
210{
211 struct spi_message msg;
212 struct spi_transfer *k_xfers;
213 struct spi_transfer *k_tmp;
214 struct spi_ioc_transfer *u_tmp;
215 unsigned n, total, tx_total, rx_total;
216 u8 *tx_buf, *rx_buf;
217 int status = -EFAULT;
218
219 spi_message_init(&msg);
220 k_xfers = kcalloc(n_xfers, sizeof(*k_tmp), GFP_KERNEL);
221 if (k_xfers == NULL)
222 return -ENOMEM;
223
224 /* Construct spi_message, copying any tx data to bounce buffer.
225 * We walk the array of user-provided transfers, using each one
226 * to initialize a kernel version of the same transfer.
227 */
228 tx_buf = spidev->tx_buffer;
229 rx_buf = spidev->rx_buffer;
230 total = 0;
231 tx_total = 0;
232 rx_total = 0;
233 for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers;
234 n;
235 n--, k_tmp++, u_tmp++) {
236 k_tmp->len = u_tmp->len;
237
238 total += k_tmp->len;
239 /* Since the function returns the total length of transfers
240 * on success, restrict the total to positive int values to
241 * avoid the return value looking like an error. Also check
242 * each transfer length to avoid arithmetic overflow.
243 */
244 if (total > INT_MAX || k_tmp->len > INT_MAX) {
245 status = -EMSGSIZE;
246 goto done;
247 }
248
249 if (u_tmp->rx_buf) {
250 /* this transfer needs space in RX bounce buffer */
251 rx_total += k_tmp->len;
252 if (rx_total > bufsiz) {
253 status = -EMSGSIZE;
254 goto done;
255 }
256 k_tmp->rx_buf = rx_buf;
257 if (!access_ok(VERIFY_WRITE, (u8 __user *)
258 (uintptr_t) u_tmp->rx_buf,
259 u_tmp->len))
260 goto done;
261 rx_buf += k_tmp->len;
262 }
263 if (u_tmp->tx_buf) {
264 /* this transfer needs space in TX bounce buffer */
265 tx_total += k_tmp->len;
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 += k_tmp->len;
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 rx_buf = spidev->rx_buffer;
306 for (n = n_xfers, u_tmp = u_xfers; n; n--, u_tmp++) {
307 if (u_tmp->rx_buf) {
308 if (__copy_to_user((u8 __user *)
309 (uintptr_t) u_tmp->rx_buf, rx_buf,
310 u_tmp->len)) {
311 status = -EFAULT;
312 goto done;
313 }
314 rx_buf += u_tmp->len;
315 }
316 }
317 status = total;
318
319done:
320 kfree(k_xfers);
321 return status;
322}
323
324static struct spi_ioc_transfer *
325spidev_get_ioc_message(unsigned int cmd, struct spi_ioc_transfer __user *u_ioc,
326 unsigned *n_ioc)
327{
328 struct spi_ioc_transfer *ioc;
329 u32 tmp;
330
331 /* Check type, command number and direction */
332 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC
333 || _IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0))
334 || _IOC_DIR(cmd) != _IOC_WRITE)
335 return ERR_PTR(-ENOTTY);
336
337 tmp = _IOC_SIZE(cmd);
338 if ((tmp % sizeof(struct spi_ioc_transfer)) != 0)
339 return ERR_PTR(-EINVAL);
340 *n_ioc = tmp / sizeof(struct spi_ioc_transfer);
341 if (*n_ioc == 0)
342 return NULL;
343
344 /* copy into scratch area */
345 ioc = kmalloc(tmp, GFP_KERNEL);
346 if (!ioc)
347 return ERR_PTR(-ENOMEM);
348 if (__copy_from_user(ioc, u_ioc, tmp)) {
349 kfree(ioc);
350 return ERR_PTR(-EFAULT);
351 }
352 return ioc;
353}
354
355static long
356spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
357{
358 int err = 0;
359 int retval = 0;
360 struct spidev_data *spidev;
361 struct spi_device *spi;
362 u32 tmp;
363 unsigned n_ioc;
364 struct spi_ioc_transfer *ioc;
365
366 /* Check type and command number */
367 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC)
368 return -ENOTTY;
369
370 /* Check access direction once here; don't repeat below.
371 * IOC_DIR is from the user perspective, while access_ok is
372 * from the kernel perspective; so they look reversed.
373 */
374 if (_IOC_DIR(cmd) & _IOC_READ)
375 err = !access_ok(VERIFY_WRITE,
376 (void __user *)arg, _IOC_SIZE(cmd));
377 if (err == 0 && _IOC_DIR(cmd) & _IOC_WRITE)
378 err = !access_ok(VERIFY_READ,
379 (void __user *)arg, _IOC_SIZE(cmd));
380 if (err)
381 return -EFAULT;
382
383 /* guard against device removal before, or while,
384 * we issue this ioctl.
385 */
386 spidev = filp->private_data;
387 spin_lock_irq(&spidev->spi_lock);
388 spi = spi_dev_get(spidev->spi);
389 spin_unlock_irq(&spidev->spi_lock);
390
391 if (spi == NULL)
392 return -ESHUTDOWN;
393
394 /* use the buffer lock here for triple duty:
395 * - prevent I/O (from us) so calling spi_setup() is safe;
396 * - prevent concurrent SPI_IOC_WR_* from morphing
397 * data fields while SPI_IOC_RD_* reads them;
398 * - SPI_IOC_MESSAGE needs the buffer locked "normally".
399 */
400 mutex_lock(&spidev->buf_lock);
401
402 switch (cmd) {
403 /* read requests */
404 case SPI_IOC_RD_MODE:
405 retval = __put_user(spi->mode & SPI_MODE_MASK,
406 (__u8 __user *)arg);
407 break;
408 case SPI_IOC_RD_MODE32:
409 retval = __put_user(spi->mode & SPI_MODE_MASK,
410 (__u32 __user *)arg);
411 break;
412 case SPI_IOC_RD_LSB_FIRST:
413 retval = __put_user((spi->mode & SPI_LSB_FIRST) ? 1 : 0,
414 (__u8 __user *)arg);
415 break;
416 case SPI_IOC_RD_BITS_PER_WORD:
417 retval = __put_user(spi->bits_per_word, (__u8 __user *)arg);
418 break;
419 case SPI_IOC_RD_MAX_SPEED_HZ:
420 retval = __put_user(spidev->speed_hz, (__u32 __user *)arg);
421 break;
422
423 /* write requests */
424 case SPI_IOC_WR_MODE:
425 case SPI_IOC_WR_MODE32:
426 if (cmd == SPI_IOC_WR_MODE)
427 retval = __get_user(tmp, (u8 __user *)arg);
428 else
429 retval = __get_user(tmp, (u32 __user *)arg);
430 if (retval == 0) {
431 u32 save = spi->mode;
432
433 if (tmp & ~SPI_MODE_MASK) {
434 retval = -EINVAL;
435 break;
436 }
437
438 tmp |= spi->mode & ~SPI_MODE_MASK;
439 spi->mode = (u16)tmp;
440 retval = spi_setup(spi);
441 if (retval < 0)
442 spi->mode = save;
443 else
444 dev_dbg(&spi->dev, "spi mode %x\n", tmp);
445 }
446 break;
447 case SPI_IOC_WR_LSB_FIRST:
448 retval = __get_user(tmp, (__u8 __user *)arg);
449 if (retval == 0) {
450 u32 save = spi->mode;
451
452 if (tmp)
453 spi->mode |= SPI_LSB_FIRST;
454 else
455 spi->mode &= ~SPI_LSB_FIRST;
456 retval = spi_setup(spi);
457 if (retval < 0)
458 spi->mode = save;
459 else
460 dev_dbg(&spi->dev, "%csb first\n",
461 tmp ? 'l' : 'm');
462 }
463 break;
464 case SPI_IOC_WR_BITS_PER_WORD:
465 retval = __get_user(tmp, (__u8 __user *)arg);
466 if (retval == 0) {
467 u8 save = spi->bits_per_word;
468
469 spi->bits_per_word = tmp;
470 retval = spi_setup(spi);
471 if (retval < 0)
472 spi->bits_per_word = save;
473 else
474 dev_dbg(&spi->dev, "%d bits per word\n", tmp);
475 }
476 break;
477 case SPI_IOC_WR_MAX_SPEED_HZ:
478 retval = __get_user(tmp, (__u32 __user *)arg);
479 if (retval == 0) {
480 u32 save = spi->max_speed_hz;
481
482 spi->max_speed_hz = tmp;
483 retval = spi_setup(spi);
484 if (retval >= 0)
485 spidev->speed_hz = tmp;
486 else
487 dev_dbg(&spi->dev, "%d Hz (max)\n", tmp);
488 spi->max_speed_hz = save;
489 }
490 break;
491
492 default:
493 /* segmented and/or full-duplex I/O request */
494 /* Check message and copy into scratch area */
495 ioc = spidev_get_ioc_message(cmd,
496 (struct spi_ioc_transfer __user *)arg, &n_ioc);
497 if (IS_ERR(ioc)) {
498 retval = PTR_ERR(ioc);
499 break;
500 }
501 if (!ioc)
502 break; /* n_ioc is also 0 */
503
504 /* translate to spi_message, execute */
505 retval = spidev_message(spidev, ioc, n_ioc);
506 kfree(ioc);
507 break;
508 }
509
510 mutex_unlock(&spidev->buf_lock);
511 spi_dev_put(spi);
512 return retval;
513}
514
515#ifdef CONFIG_COMPAT
516static long
517spidev_compat_ioc_message(struct file *filp, unsigned int cmd,
518 unsigned long arg)
519{
520 struct spi_ioc_transfer __user *u_ioc;
521 int retval = 0;
522 struct spidev_data *spidev;
523 struct spi_device *spi;
524 unsigned n_ioc, n;
525 struct spi_ioc_transfer *ioc;
526
527 u_ioc = (struct spi_ioc_transfer __user *) compat_ptr(arg);
528 if (!access_ok(VERIFY_READ, u_ioc, _IOC_SIZE(cmd)))
529 return -EFAULT;
530
531 /* guard against device removal before, or while,
532 * we issue this ioctl.
533 */
534 spidev = filp->private_data;
535 spin_lock_irq(&spidev->spi_lock);
536 spi = spi_dev_get(spidev->spi);
537 spin_unlock_irq(&spidev->spi_lock);
538
539 if (spi == NULL)
540 return -ESHUTDOWN;
541
542 /* SPI_IOC_MESSAGE needs the buffer locked "normally" */
543 mutex_lock(&spidev->buf_lock);
544
545 /* Check message and copy into scratch area */
546 ioc = spidev_get_ioc_message(cmd, u_ioc, &n_ioc);
547 if (IS_ERR(ioc)) {
548 retval = PTR_ERR(ioc);
549 goto done;
550 }
551 if (!ioc)
552 goto done; /* n_ioc is also 0 */
553
554 /* Convert buffer pointers */
555 for (n = 0; n < n_ioc; n++) {
556 ioc[n].rx_buf = (uintptr_t) compat_ptr(ioc[n].rx_buf);
557 ioc[n].tx_buf = (uintptr_t) compat_ptr(ioc[n].tx_buf);
558 }
559
560 /* translate to spi_message, execute */
561 retval = spidev_message(spidev, ioc, n_ioc);
562 kfree(ioc);
563
564done:
565 mutex_unlock(&spidev->buf_lock);
566 spi_dev_put(spi);
567 return retval;
568}
569
570static long
571spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
572{
573 if (_IOC_TYPE(cmd) == SPI_IOC_MAGIC
574 && _IOC_NR(cmd) == _IOC_NR(SPI_IOC_MESSAGE(0))
575 && _IOC_DIR(cmd) == _IOC_WRITE)
576 return spidev_compat_ioc_message(filp, cmd, arg);
577
578 return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
579}
580#else
581#define spidev_compat_ioctl NULL
582#endif /* CONFIG_COMPAT */
583
584static int spidev_open(struct inode *inode, struct file *filp)
585{
586 struct spidev_data *spidev;
587 int status = -ENXIO;
588
589 mutex_lock(&device_list_lock);
590
591 list_for_each_entry(spidev, &device_list, device_entry) {
592 if (spidev->devt == inode->i_rdev) {
593 status = 0;
594 break;
595 }
596 }
597
598 if (status) {
599 pr_debug("spidev: nothing for minor %d\n", iminor(inode));
600 goto err_find_dev;
601 }
602
603 if (!spidev->tx_buffer) {
604 spidev->tx_buffer = kmalloc(bufsiz, GFP_KERNEL);
605 if (!spidev->tx_buffer) {
606 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
607 status = -ENOMEM;
608 goto err_find_dev;
609 }
610 }
611
612 if (!spidev->rx_buffer) {
613 spidev->rx_buffer = kmalloc(bufsiz, GFP_KERNEL);
614 if (!spidev->rx_buffer) {
615 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
616 status = -ENOMEM;
617 goto err_alloc_rx_buf;
618 }
619 }
620
621 spidev->users++;
622 filp->private_data = spidev;
623 nonseekable_open(inode, filp);
624
625 mutex_unlock(&device_list_lock);
626 return 0;
627
628err_alloc_rx_buf:
629 kfree(spidev->tx_buffer);
630 spidev->tx_buffer = NULL;
631err_find_dev:
632 mutex_unlock(&device_list_lock);
633 return status;
634}
635
636static int spidev_release(struct inode *inode, struct file *filp)
637{
638 struct spidev_data *spidev;
639
640 mutex_lock(&device_list_lock);
641 spidev = filp->private_data;
642 filp->private_data = NULL;
643
644 /* last close? */
645 spidev->users--;
646 if (!spidev->users) {
647 int dofree;
648
649 kfree(spidev->tx_buffer);
650 spidev->tx_buffer = NULL;
651
652 kfree(spidev->rx_buffer);
653 spidev->rx_buffer = NULL;
654
655 spin_lock_irq(&spidev->spi_lock);
656 if (spidev->spi)
657 spidev->speed_hz = spidev->spi->max_speed_hz;
658
659 /* ... after we unbound from the underlying device? */
660 dofree = (spidev->spi == NULL);
661 spin_unlock_irq(&spidev->spi_lock);
662
663 if (dofree)
664 kfree(spidev);
665 }
666 mutex_unlock(&device_list_lock);
667
668 return 0;
669}
670
671static const struct file_operations spidev_fops = {
672 .owner = THIS_MODULE,
673 /* REVISIT switch to aio primitives, so that userspace
674 * gets more complete API coverage. It'll simplify things
675 * too, except for the locking.
676 */
677 .write = spidev_write,
678 .read = spidev_read,
679 .unlocked_ioctl = spidev_ioctl,
680 .compat_ioctl = spidev_compat_ioctl,
681 .open = spidev_open,
682 .release = spidev_release,
683 .llseek = no_llseek,
684};
685
686/*-------------------------------------------------------------------------*/
687
688/* The main reason to have this class is to make mdev/udev create the
689 * /dev/spidevB.C character device nodes exposing our userspace API.
690 * It also simplifies memory management.
691 */
692
693static struct class *spidev_class;
694
695#ifdef CONFIG_OF
696static const struct of_device_id spidev_dt_ids[] = {
697 { .compatible = "rohm,dh2228fv" },
698 { .compatible = "lineartechnology,ltc2488" },
699 { .compatible = "ge,achc" },
700 {},
701};
702MODULE_DEVICE_TABLE(of, spidev_dt_ids);
703#endif
704
705#ifdef CONFIG_ACPI
706
707/* Dummy SPI devices not to be used in production systems */
708#define SPIDEV_ACPI_DUMMY 1
709
710static const struct acpi_device_id spidev_acpi_ids[] = {
711 /*
712 * The ACPI SPT000* devices are only meant for development and
713 * testing. Systems used in production should have a proper ACPI
714 * description of the connected peripheral and they should also use
715 * a proper driver instead of poking directly to the SPI bus.
716 */
717 { "SPT0001", SPIDEV_ACPI_DUMMY },
718 { "SPT0002", SPIDEV_ACPI_DUMMY },
719 { "SPT0003", SPIDEV_ACPI_DUMMY },
720 {},
721};
722MODULE_DEVICE_TABLE(acpi, spidev_acpi_ids);
723
724static void spidev_probe_acpi(struct spi_device *spi)
725{
726 const struct acpi_device_id *id;
727
728 if (!has_acpi_companion(&spi->dev))
729 return;
730
731 id = acpi_match_device(spidev_acpi_ids, &spi->dev);
732 if (WARN_ON(!id))
733 return;
734
735 if (id->driver_data == SPIDEV_ACPI_DUMMY)
736 dev_warn(&spi->dev, "do not use this driver in production systems!\n");
737}
738#else
739static inline void spidev_probe_acpi(struct spi_device *spi) {}
740#endif
741
742/*-------------------------------------------------------------------------*/
743
744static int spidev_probe(struct spi_device *spi)
745{
746 struct spidev_data *spidev;
747 int status;
748 unsigned long minor;
749
750 /*
751 * spidev should never be referenced in DT without a specific
752 * compatible string, it is a Linux implementation thing
753 * rather than a description of the hardware.
754 */
755 if (spi->dev.of_node && !of_match_device(spidev_dt_ids, &spi->dev)) {
756 dev_err(&spi->dev, "buggy DT: spidev listed directly in DT\n");
757 WARN_ON(spi->dev.of_node &&
758 !of_match_device(spidev_dt_ids, &spi->dev));
759 }
760
761 spidev_probe_acpi(spi);
762
763 /* Allocate driver data */
764 spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);
765 if (!spidev)
766 return -ENOMEM;
767
768 /* Initialize the driver data */
769 spidev->spi = spi;
770 spin_lock_init(&spidev->spi_lock);
771 mutex_init(&spidev->buf_lock);
772
773 INIT_LIST_HEAD(&spidev->device_entry);
774
775 /* If we can allocate a minor number, hook up this device.
776 * Reusing minors is fine so long as udev or mdev is working.
777 */
778 mutex_lock(&device_list_lock);
779 minor = find_first_zero_bit(minors, N_SPI_MINORS);
780 if (minor < N_SPI_MINORS) {
781 struct device *dev;
782
783 spidev->devt = MKDEV(SPIDEV_MAJOR, minor);
784 dev = device_create(spidev_class, &spi->dev, spidev->devt,
785 spidev, "spidev%d.%d",
786 spi->master->bus_num, spi->chip_select);
787 status = PTR_ERR_OR_ZERO(dev);
788 } else {
789 dev_dbg(&spi->dev, "no minor number available!\n");
790 status = -ENODEV;
791 }
792 if (status == 0) {
793 set_bit(minor, minors);
794 list_add(&spidev->device_entry, &device_list);
795 }
796 mutex_unlock(&device_list_lock);
797
798 spidev->speed_hz = spi->max_speed_hz;
799
800 if (status == 0)
801 spi_set_drvdata(spi, spidev);
802 else
803 kfree(spidev);
804
805 return status;
806}
807
808static int spidev_remove(struct spi_device *spi)
809{
810 struct spidev_data *spidev = spi_get_drvdata(spi);
811
812 /* make sure ops on existing fds can abort cleanly */
813 spin_lock_irq(&spidev->spi_lock);
814 spidev->spi = NULL;
815 spin_unlock_irq(&spidev->spi_lock);
816
817 /* prevent new opens */
818 mutex_lock(&device_list_lock);
819 list_del(&spidev->device_entry);
820 device_destroy(spidev_class, spidev->devt);
821 clear_bit(MINOR(spidev->devt), minors);
822 if (spidev->users == 0)
823 kfree(spidev);
824 mutex_unlock(&device_list_lock);
825
826 return 0;
827}
828
829static struct spi_driver spidev_spi_driver = {
830 .driver = {
831 .name = "spidev",
832 .of_match_table = of_match_ptr(spidev_dt_ids),
833 .acpi_match_table = ACPI_PTR(spidev_acpi_ids),
834 },
835 .probe = spidev_probe,
836 .remove = spidev_remove,
837
838 /* NOTE: suspend/resume methods are not necessary here.
839 * We don't do anything except pass the requests to/from
840 * the underlying controller. The refrigerator handles
841 * most issues; the controller driver handles the rest.
842 */
843};
844
845/*-------------------------------------------------------------------------*/
846
847static int __init spidev_init(void)
848{
849 int status;
850
851 /* Claim our 256 reserved device numbers. Then register a class
852 * that will key udev/mdev to add/remove /dev nodes. Last, register
853 * the driver which manages those device numbers.
854 */
855 BUILD_BUG_ON(N_SPI_MINORS > 256);
856 status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);
857 if (status < 0)
858 return status;
859
860 spidev_class = class_create(THIS_MODULE, "spidev");
861 if (IS_ERR(spidev_class)) {
862 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
863 return PTR_ERR(spidev_class);
864 }
865
866 status = spi_register_driver(&spidev_spi_driver);
867 if (status < 0) {
868 class_destroy(spidev_class);
869 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
870 }
871 return status;
872}
873module_init(spidev_init);
874
875static void __exit spidev_exit(void)
876{
877 spi_unregister_driver(&spidev_spi_driver);
878 class_destroy(spidev_class);
879 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
880}
881module_exit(spidev_exit);
882
883MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>");
884MODULE_DESCRIPTION("User mode SPI device interface");
885MODULE_LICENSE("GPL");
886MODULE_ALIAS("spi:spidev");
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Simple synchronous userspace interface to SPI devices
4 *
5 * Copyright (C) 2006 SWAPP
6 * Andrea Paterniani <a.paterniani@swapp-eng.it>
7 * Copyright (C) 2007 David Brownell (simplification, cleanup)
8 */
9
10#include <linux/init.h>
11#include <linux/module.h>
12#include <linux/ioctl.h>
13#include <linux/fs.h>
14#include <linux/device.h>
15#include <linux/err.h>
16#include <linux/list.h>
17#include <linux/errno.h>
18#include <linux/mutex.h>
19#include <linux/slab.h>
20#include <linux/compat.h>
21#include <linux/of.h>
22#include <linux/of_device.h>
23#include <linux/acpi.h>
24
25#include <linux/spi/spi.h>
26#include <linux/spi/spidev.h>
27
28#include <linux/uaccess.h>
29
30
31/*
32 * This supports access to SPI devices using normal userspace I/O calls.
33 * Note that while traditional UNIX/POSIX I/O semantics are half duplex,
34 * and often mask message boundaries, full SPI support requires full duplex
35 * transfers. There are several kinds of internal message boundaries to
36 * handle chipselect management and other protocol options.
37 *
38 * SPI has a character major number assigned. We allocate minor numbers
39 * dynamically using a bitmask. You must use hotplug tools, such as udev
40 * (or mdev with busybox) to create and destroy the /dev/spidevB.C device
41 * nodes, since there is no fixed association of minor numbers with any
42 * particular SPI bus or device.
43 */
44#define SPIDEV_MAJOR 153 /* assigned */
45#define N_SPI_MINORS 32 /* ... up to 256 */
46
47static DECLARE_BITMAP(minors, N_SPI_MINORS);
48
49
50/* Bit masks for spi_device.mode management. Note that incorrect
51 * settings for some settings can cause *lots* of trouble for other
52 * devices on a shared bus:
53 *
54 * - CS_HIGH ... this device will be active when it shouldn't be
55 * - 3WIRE ... when active, it won't behave as it should
56 * - NO_CS ... there will be no explicit message boundaries; this
57 * is completely incompatible with the shared bus model
58 * - READY ... transfers may proceed when they shouldn't.
59 *
60 * REVISIT should changing those flags be privileged?
61 */
62#define SPI_MODE_MASK (SPI_CPHA | SPI_CPOL | SPI_CS_HIGH \
63 | SPI_LSB_FIRST | SPI_3WIRE | SPI_LOOP \
64 | SPI_NO_CS | SPI_READY | SPI_TX_DUAL \
65 | SPI_TX_QUAD | SPI_RX_DUAL | SPI_RX_QUAD)
66
67struct spidev_data {
68 dev_t devt;
69 spinlock_t spi_lock;
70 struct spi_device *spi;
71 struct list_head device_entry;
72
73 /* TX/RX buffers are NULL unless this device is open (users > 0) */
74 struct mutex buf_lock;
75 unsigned users;
76 u8 *tx_buffer;
77 u8 *rx_buffer;
78 u32 speed_hz;
79};
80
81static LIST_HEAD(device_list);
82static DEFINE_MUTEX(device_list_lock);
83
84static unsigned bufsiz = 4096;
85module_param(bufsiz, uint, S_IRUGO);
86MODULE_PARM_DESC(bufsiz, "data bytes in biggest supported SPI message");
87
88/*-------------------------------------------------------------------------*/
89
90static ssize_t
91spidev_sync(struct spidev_data *spidev, struct spi_message *message)
92{
93 int status;
94 struct spi_device *spi;
95
96 spin_lock_irq(&spidev->spi_lock);
97 spi = spidev->spi;
98 spin_unlock_irq(&spidev->spi_lock);
99
100 if (spi == NULL)
101 status = -ESHUTDOWN;
102 else
103 status = spi_sync(spi, message);
104
105 if (status == 0)
106 status = message->actual_length;
107
108 return status;
109}
110
111static inline ssize_t
112spidev_sync_write(struct spidev_data *spidev, size_t len)
113{
114 struct spi_transfer t = {
115 .tx_buf = spidev->tx_buffer,
116 .len = len,
117 .speed_hz = spidev->speed_hz,
118 };
119 struct spi_message m;
120
121 spi_message_init(&m);
122 spi_message_add_tail(&t, &m);
123 return spidev_sync(spidev, &m);
124}
125
126static inline ssize_t
127spidev_sync_read(struct spidev_data *spidev, size_t len)
128{
129 struct spi_transfer t = {
130 .rx_buf = spidev->rx_buffer,
131 .len = len,
132 .speed_hz = spidev->speed_hz,
133 };
134 struct spi_message m;
135
136 spi_message_init(&m);
137 spi_message_add_tail(&t, &m);
138 return spidev_sync(spidev, &m);
139}
140
141/*-------------------------------------------------------------------------*/
142
143/* Read-only message with current device setup */
144static ssize_t
145spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
146{
147 struct spidev_data *spidev;
148 ssize_t status = 0;
149
150 /* chipselect only toggles at start or end of operation */
151 if (count > bufsiz)
152 return -EMSGSIZE;
153
154 spidev = filp->private_data;
155
156 mutex_lock(&spidev->buf_lock);
157 status = spidev_sync_read(spidev, count);
158 if (status > 0) {
159 unsigned long missing;
160
161 missing = copy_to_user(buf, spidev->rx_buffer, status);
162 if (missing == status)
163 status = -EFAULT;
164 else
165 status = status - missing;
166 }
167 mutex_unlock(&spidev->buf_lock);
168
169 return status;
170}
171
172/* Write-only message with current device setup */
173static ssize_t
174spidev_write(struct file *filp, const char __user *buf,
175 size_t count, loff_t *f_pos)
176{
177 struct spidev_data *spidev;
178 ssize_t status = 0;
179 unsigned long missing;
180
181 /* chipselect only toggles at start or end of operation */
182 if (count > bufsiz)
183 return -EMSGSIZE;
184
185 spidev = filp->private_data;
186
187 mutex_lock(&spidev->buf_lock);
188 missing = copy_from_user(spidev->tx_buffer, buf, count);
189 if (missing == 0)
190 status = spidev_sync_write(spidev, count);
191 else
192 status = -EFAULT;
193 mutex_unlock(&spidev->buf_lock);
194
195 return status;
196}
197
198static int spidev_message(struct spidev_data *spidev,
199 struct spi_ioc_transfer *u_xfers, unsigned n_xfers)
200{
201 struct spi_message msg;
202 struct spi_transfer *k_xfers;
203 struct spi_transfer *k_tmp;
204 struct spi_ioc_transfer *u_tmp;
205 unsigned n, total, tx_total, rx_total;
206 u8 *tx_buf, *rx_buf;
207 int status = -EFAULT;
208
209 spi_message_init(&msg);
210 k_xfers = kcalloc(n_xfers, sizeof(*k_tmp), GFP_KERNEL);
211 if (k_xfers == NULL)
212 return -ENOMEM;
213
214 /* Construct spi_message, copying any tx data to bounce buffer.
215 * We walk the array of user-provided transfers, using each one
216 * to initialize a kernel version of the same transfer.
217 */
218 tx_buf = spidev->tx_buffer;
219 rx_buf = spidev->rx_buffer;
220 total = 0;
221 tx_total = 0;
222 rx_total = 0;
223 for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers;
224 n;
225 n--, k_tmp++, u_tmp++) {
226 k_tmp->len = u_tmp->len;
227
228 total += k_tmp->len;
229 /* Since the function returns the total length of transfers
230 * on success, restrict the total to positive int values to
231 * avoid the return value looking like an error. Also check
232 * each transfer length to avoid arithmetic overflow.
233 */
234 if (total > INT_MAX || k_tmp->len > INT_MAX) {
235 status = -EMSGSIZE;
236 goto done;
237 }
238
239 if (u_tmp->rx_buf) {
240 /* this transfer needs space in RX bounce buffer */
241 rx_total += k_tmp->len;
242 if (rx_total > bufsiz) {
243 status = -EMSGSIZE;
244 goto done;
245 }
246 k_tmp->rx_buf = rx_buf;
247 rx_buf += k_tmp->len;
248 }
249 if (u_tmp->tx_buf) {
250 /* this transfer needs space in TX bounce buffer */
251 tx_total += k_tmp->len;
252 if (tx_total > bufsiz) {
253 status = -EMSGSIZE;
254 goto done;
255 }
256 k_tmp->tx_buf = tx_buf;
257 if (copy_from_user(tx_buf, (const u8 __user *)
258 (uintptr_t) u_tmp->tx_buf,
259 u_tmp->len))
260 goto done;
261 tx_buf += k_tmp->len;
262 }
263
264 k_tmp->cs_change = !!u_tmp->cs_change;
265 k_tmp->tx_nbits = u_tmp->tx_nbits;
266 k_tmp->rx_nbits = u_tmp->rx_nbits;
267 k_tmp->bits_per_word = u_tmp->bits_per_word;
268 k_tmp->delay_usecs = u_tmp->delay_usecs;
269 k_tmp->speed_hz = u_tmp->speed_hz;
270 k_tmp->word_delay_usecs = u_tmp->word_delay_usecs;
271 if (!k_tmp->speed_hz)
272 k_tmp->speed_hz = spidev->speed_hz;
273#ifdef VERBOSE
274 dev_dbg(&spidev->spi->dev,
275 " xfer len %u %s%s%s%dbits %u usec %u usec %uHz\n",
276 u_tmp->len,
277 u_tmp->rx_buf ? "rx " : "",
278 u_tmp->tx_buf ? "tx " : "",
279 u_tmp->cs_change ? "cs " : "",
280 u_tmp->bits_per_word ? : spidev->spi->bits_per_word,
281 u_tmp->delay_usecs,
282 u_tmp->word_delay_usecs,
283 u_tmp->speed_hz ? : spidev->spi->max_speed_hz);
284#endif
285 spi_message_add_tail(k_tmp, &msg);
286 }
287
288 status = spidev_sync(spidev, &msg);
289 if (status < 0)
290 goto done;
291
292 /* copy any rx data out of bounce buffer */
293 rx_buf = spidev->rx_buffer;
294 for (n = n_xfers, u_tmp = u_xfers; n; n--, u_tmp++) {
295 if (u_tmp->rx_buf) {
296 if (copy_to_user((u8 __user *)
297 (uintptr_t) u_tmp->rx_buf, rx_buf,
298 u_tmp->len)) {
299 status = -EFAULT;
300 goto done;
301 }
302 rx_buf += u_tmp->len;
303 }
304 }
305 status = total;
306
307done:
308 kfree(k_xfers);
309 return status;
310}
311
312static struct spi_ioc_transfer *
313spidev_get_ioc_message(unsigned int cmd, struct spi_ioc_transfer __user *u_ioc,
314 unsigned *n_ioc)
315{
316 u32 tmp;
317
318 /* Check type, command number and direction */
319 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC
320 || _IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0))
321 || _IOC_DIR(cmd) != _IOC_WRITE)
322 return ERR_PTR(-ENOTTY);
323
324 tmp = _IOC_SIZE(cmd);
325 if ((tmp % sizeof(struct spi_ioc_transfer)) != 0)
326 return ERR_PTR(-EINVAL);
327 *n_ioc = tmp / sizeof(struct spi_ioc_transfer);
328 if (*n_ioc == 0)
329 return NULL;
330
331 /* copy into scratch area */
332 return memdup_user(u_ioc, tmp);
333}
334
335static long
336spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
337{
338 int retval = 0;
339 struct spidev_data *spidev;
340 struct spi_device *spi;
341 u32 tmp;
342 unsigned n_ioc;
343 struct spi_ioc_transfer *ioc;
344
345 /* Check type and command number */
346 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC)
347 return -ENOTTY;
348
349 /* guard against device removal before, or while,
350 * we issue this ioctl.
351 */
352 spidev = filp->private_data;
353 spin_lock_irq(&spidev->spi_lock);
354 spi = spi_dev_get(spidev->spi);
355 spin_unlock_irq(&spidev->spi_lock);
356
357 if (spi == NULL)
358 return -ESHUTDOWN;
359
360 /* use the buffer lock here for triple duty:
361 * - prevent I/O (from us) so calling spi_setup() is safe;
362 * - prevent concurrent SPI_IOC_WR_* from morphing
363 * data fields while SPI_IOC_RD_* reads them;
364 * - SPI_IOC_MESSAGE needs the buffer locked "normally".
365 */
366 mutex_lock(&spidev->buf_lock);
367
368 switch (cmd) {
369 /* read requests */
370 case SPI_IOC_RD_MODE:
371 retval = put_user(spi->mode & SPI_MODE_MASK,
372 (__u8 __user *)arg);
373 break;
374 case SPI_IOC_RD_MODE32:
375 retval = put_user(spi->mode & SPI_MODE_MASK,
376 (__u32 __user *)arg);
377 break;
378 case SPI_IOC_RD_LSB_FIRST:
379 retval = put_user((spi->mode & SPI_LSB_FIRST) ? 1 : 0,
380 (__u8 __user *)arg);
381 break;
382 case SPI_IOC_RD_BITS_PER_WORD:
383 retval = put_user(spi->bits_per_word, (__u8 __user *)arg);
384 break;
385 case SPI_IOC_RD_MAX_SPEED_HZ:
386 retval = put_user(spidev->speed_hz, (__u32 __user *)arg);
387 break;
388
389 /* write requests */
390 case SPI_IOC_WR_MODE:
391 case SPI_IOC_WR_MODE32:
392 if (cmd == SPI_IOC_WR_MODE)
393 retval = get_user(tmp, (u8 __user *)arg);
394 else
395 retval = get_user(tmp, (u32 __user *)arg);
396 if (retval == 0) {
397 u32 save = spi->mode;
398
399 if (tmp & ~SPI_MODE_MASK) {
400 retval = -EINVAL;
401 break;
402 }
403
404 tmp |= spi->mode & ~SPI_MODE_MASK;
405 spi->mode = (u16)tmp;
406 retval = spi_setup(spi);
407 if (retval < 0)
408 spi->mode = save;
409 else
410 dev_dbg(&spi->dev, "spi mode %x\n", tmp);
411 }
412 break;
413 case SPI_IOC_WR_LSB_FIRST:
414 retval = get_user(tmp, (__u8 __user *)arg);
415 if (retval == 0) {
416 u32 save = spi->mode;
417
418 if (tmp)
419 spi->mode |= SPI_LSB_FIRST;
420 else
421 spi->mode &= ~SPI_LSB_FIRST;
422 retval = spi_setup(spi);
423 if (retval < 0)
424 spi->mode = save;
425 else
426 dev_dbg(&spi->dev, "%csb first\n",
427 tmp ? 'l' : 'm');
428 }
429 break;
430 case SPI_IOC_WR_BITS_PER_WORD:
431 retval = get_user(tmp, (__u8 __user *)arg);
432 if (retval == 0) {
433 u8 save = spi->bits_per_word;
434
435 spi->bits_per_word = tmp;
436 retval = spi_setup(spi);
437 if (retval < 0)
438 spi->bits_per_word = save;
439 else
440 dev_dbg(&spi->dev, "%d bits per word\n", tmp);
441 }
442 break;
443 case SPI_IOC_WR_MAX_SPEED_HZ:
444 retval = get_user(tmp, (__u32 __user *)arg);
445 if (retval == 0) {
446 u32 save = spi->max_speed_hz;
447
448 spi->max_speed_hz = tmp;
449 retval = spi_setup(spi);
450 if (retval >= 0)
451 spidev->speed_hz = tmp;
452 else
453 dev_dbg(&spi->dev, "%d Hz (max)\n", tmp);
454 spi->max_speed_hz = save;
455 }
456 break;
457
458 default:
459 /* segmented and/or full-duplex I/O request */
460 /* Check message and copy into scratch area */
461 ioc = spidev_get_ioc_message(cmd,
462 (struct spi_ioc_transfer __user *)arg, &n_ioc);
463 if (IS_ERR(ioc)) {
464 retval = PTR_ERR(ioc);
465 break;
466 }
467 if (!ioc)
468 break; /* n_ioc is also 0 */
469
470 /* translate to spi_message, execute */
471 retval = spidev_message(spidev, ioc, n_ioc);
472 kfree(ioc);
473 break;
474 }
475
476 mutex_unlock(&spidev->buf_lock);
477 spi_dev_put(spi);
478 return retval;
479}
480
481#ifdef CONFIG_COMPAT
482static long
483spidev_compat_ioc_message(struct file *filp, unsigned int cmd,
484 unsigned long arg)
485{
486 struct spi_ioc_transfer __user *u_ioc;
487 int retval = 0;
488 struct spidev_data *spidev;
489 struct spi_device *spi;
490 unsigned n_ioc, n;
491 struct spi_ioc_transfer *ioc;
492
493 u_ioc = (struct spi_ioc_transfer __user *) compat_ptr(arg);
494
495 /* guard against device removal before, or while,
496 * we issue this ioctl.
497 */
498 spidev = filp->private_data;
499 spin_lock_irq(&spidev->spi_lock);
500 spi = spi_dev_get(spidev->spi);
501 spin_unlock_irq(&spidev->spi_lock);
502
503 if (spi == NULL)
504 return -ESHUTDOWN;
505
506 /* SPI_IOC_MESSAGE needs the buffer locked "normally" */
507 mutex_lock(&spidev->buf_lock);
508
509 /* Check message and copy into scratch area */
510 ioc = spidev_get_ioc_message(cmd, u_ioc, &n_ioc);
511 if (IS_ERR(ioc)) {
512 retval = PTR_ERR(ioc);
513 goto done;
514 }
515 if (!ioc)
516 goto done; /* n_ioc is also 0 */
517
518 /* Convert buffer pointers */
519 for (n = 0; n < n_ioc; n++) {
520 ioc[n].rx_buf = (uintptr_t) compat_ptr(ioc[n].rx_buf);
521 ioc[n].tx_buf = (uintptr_t) compat_ptr(ioc[n].tx_buf);
522 }
523
524 /* translate to spi_message, execute */
525 retval = spidev_message(spidev, ioc, n_ioc);
526 kfree(ioc);
527
528done:
529 mutex_unlock(&spidev->buf_lock);
530 spi_dev_put(spi);
531 return retval;
532}
533
534static long
535spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
536{
537 if (_IOC_TYPE(cmd) == SPI_IOC_MAGIC
538 && _IOC_NR(cmd) == _IOC_NR(SPI_IOC_MESSAGE(0))
539 && _IOC_DIR(cmd) == _IOC_WRITE)
540 return spidev_compat_ioc_message(filp, cmd, arg);
541
542 return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
543}
544#else
545#define spidev_compat_ioctl NULL
546#endif /* CONFIG_COMPAT */
547
548static int spidev_open(struct inode *inode, struct file *filp)
549{
550 struct spidev_data *spidev;
551 int status = -ENXIO;
552
553 mutex_lock(&device_list_lock);
554
555 list_for_each_entry(spidev, &device_list, device_entry) {
556 if (spidev->devt == inode->i_rdev) {
557 status = 0;
558 break;
559 }
560 }
561
562 if (status) {
563 pr_debug("spidev: nothing for minor %d\n", iminor(inode));
564 goto err_find_dev;
565 }
566
567 if (!spidev->tx_buffer) {
568 spidev->tx_buffer = kmalloc(bufsiz, GFP_KERNEL);
569 if (!spidev->tx_buffer) {
570 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
571 status = -ENOMEM;
572 goto err_find_dev;
573 }
574 }
575
576 if (!spidev->rx_buffer) {
577 spidev->rx_buffer = kmalloc(bufsiz, GFP_KERNEL);
578 if (!spidev->rx_buffer) {
579 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
580 status = -ENOMEM;
581 goto err_alloc_rx_buf;
582 }
583 }
584
585 spidev->users++;
586 filp->private_data = spidev;
587 stream_open(inode, filp);
588
589 mutex_unlock(&device_list_lock);
590 return 0;
591
592err_alloc_rx_buf:
593 kfree(spidev->tx_buffer);
594 spidev->tx_buffer = NULL;
595err_find_dev:
596 mutex_unlock(&device_list_lock);
597 return status;
598}
599
600static int spidev_release(struct inode *inode, struct file *filp)
601{
602 struct spidev_data *spidev;
603
604 mutex_lock(&device_list_lock);
605 spidev = filp->private_data;
606 filp->private_data = NULL;
607
608 /* last close? */
609 spidev->users--;
610 if (!spidev->users) {
611 int dofree;
612
613 kfree(spidev->tx_buffer);
614 spidev->tx_buffer = NULL;
615
616 kfree(spidev->rx_buffer);
617 spidev->rx_buffer = NULL;
618
619 spin_lock_irq(&spidev->spi_lock);
620 if (spidev->spi)
621 spidev->speed_hz = spidev->spi->max_speed_hz;
622
623 /* ... after we unbound from the underlying device? */
624 dofree = (spidev->spi == NULL);
625 spin_unlock_irq(&spidev->spi_lock);
626
627 if (dofree)
628 kfree(spidev);
629 }
630 mutex_unlock(&device_list_lock);
631
632 return 0;
633}
634
635static const struct file_operations spidev_fops = {
636 .owner = THIS_MODULE,
637 /* REVISIT switch to aio primitives, so that userspace
638 * gets more complete API coverage. It'll simplify things
639 * too, except for the locking.
640 */
641 .write = spidev_write,
642 .read = spidev_read,
643 .unlocked_ioctl = spidev_ioctl,
644 .compat_ioctl = spidev_compat_ioctl,
645 .open = spidev_open,
646 .release = spidev_release,
647 .llseek = no_llseek,
648};
649
650/*-------------------------------------------------------------------------*/
651
652/* The main reason to have this class is to make mdev/udev create the
653 * /dev/spidevB.C character device nodes exposing our userspace API.
654 * It also simplifies memory management.
655 */
656
657static struct class *spidev_class;
658
659#ifdef CONFIG_OF
660static const struct of_device_id spidev_dt_ids[] = {
661 { .compatible = "rohm,dh2228fv" },
662 { .compatible = "lineartechnology,ltc2488" },
663 { .compatible = "ge,achc" },
664 { .compatible = "semtech,sx1301" },
665 { .compatible = "lwn,bk4" },
666 { .compatible = "dh,dhcom-board" },
667 { .compatible = "menlo,m53cpld" },
668 {},
669};
670MODULE_DEVICE_TABLE(of, spidev_dt_ids);
671#endif
672
673#ifdef CONFIG_ACPI
674
675/* Dummy SPI devices not to be used in production systems */
676#define SPIDEV_ACPI_DUMMY 1
677
678static const struct acpi_device_id spidev_acpi_ids[] = {
679 /*
680 * The ACPI SPT000* devices are only meant for development and
681 * testing. Systems used in production should have a proper ACPI
682 * description of the connected peripheral and they should also use
683 * a proper driver instead of poking directly to the SPI bus.
684 */
685 { "SPT0001", SPIDEV_ACPI_DUMMY },
686 { "SPT0002", SPIDEV_ACPI_DUMMY },
687 { "SPT0003", SPIDEV_ACPI_DUMMY },
688 {},
689};
690MODULE_DEVICE_TABLE(acpi, spidev_acpi_ids);
691
692static void spidev_probe_acpi(struct spi_device *spi)
693{
694 const struct acpi_device_id *id;
695
696 if (!has_acpi_companion(&spi->dev))
697 return;
698
699 id = acpi_match_device(spidev_acpi_ids, &spi->dev);
700 if (WARN_ON(!id))
701 return;
702
703 if (id->driver_data == SPIDEV_ACPI_DUMMY)
704 dev_warn(&spi->dev, "do not use this driver in production systems!\n");
705}
706#else
707static inline void spidev_probe_acpi(struct spi_device *spi) {}
708#endif
709
710/*-------------------------------------------------------------------------*/
711
712static int spidev_probe(struct spi_device *spi)
713{
714 struct spidev_data *spidev;
715 int status;
716 unsigned long minor;
717
718 /*
719 * spidev should never be referenced in DT without a specific
720 * compatible string, it is a Linux implementation thing
721 * rather than a description of the hardware.
722 */
723 WARN(spi->dev.of_node &&
724 of_device_is_compatible(spi->dev.of_node, "spidev"),
725 "%pOF: buggy DT: spidev listed directly in DT\n", spi->dev.of_node);
726
727 spidev_probe_acpi(spi);
728
729 /* Allocate driver data */
730 spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);
731 if (!spidev)
732 return -ENOMEM;
733
734 /* Initialize the driver data */
735 spidev->spi = spi;
736 spin_lock_init(&spidev->spi_lock);
737 mutex_init(&spidev->buf_lock);
738
739 INIT_LIST_HEAD(&spidev->device_entry);
740
741 /* If we can allocate a minor number, hook up this device.
742 * Reusing minors is fine so long as udev or mdev is working.
743 */
744 mutex_lock(&device_list_lock);
745 minor = find_first_zero_bit(minors, N_SPI_MINORS);
746 if (minor < N_SPI_MINORS) {
747 struct device *dev;
748
749 spidev->devt = MKDEV(SPIDEV_MAJOR, minor);
750 dev = device_create(spidev_class, &spi->dev, spidev->devt,
751 spidev, "spidev%d.%d",
752 spi->master->bus_num, spi->chip_select);
753 status = PTR_ERR_OR_ZERO(dev);
754 } else {
755 dev_dbg(&spi->dev, "no minor number available!\n");
756 status = -ENODEV;
757 }
758 if (status == 0) {
759 set_bit(minor, minors);
760 list_add(&spidev->device_entry, &device_list);
761 }
762 mutex_unlock(&device_list_lock);
763
764 spidev->speed_hz = spi->max_speed_hz;
765
766 if (status == 0)
767 spi_set_drvdata(spi, spidev);
768 else
769 kfree(spidev);
770
771 return status;
772}
773
774static int spidev_remove(struct spi_device *spi)
775{
776 struct spidev_data *spidev = spi_get_drvdata(spi);
777
778 /* make sure ops on existing fds can abort cleanly */
779 spin_lock_irq(&spidev->spi_lock);
780 spidev->spi = NULL;
781 spin_unlock_irq(&spidev->spi_lock);
782
783 /* prevent new opens */
784 mutex_lock(&device_list_lock);
785 list_del(&spidev->device_entry);
786 device_destroy(spidev_class, spidev->devt);
787 clear_bit(MINOR(spidev->devt), minors);
788 if (spidev->users == 0)
789 kfree(spidev);
790 mutex_unlock(&device_list_lock);
791
792 return 0;
793}
794
795static struct spi_driver spidev_spi_driver = {
796 .driver = {
797 .name = "spidev",
798 .of_match_table = of_match_ptr(spidev_dt_ids),
799 .acpi_match_table = ACPI_PTR(spidev_acpi_ids),
800 },
801 .probe = spidev_probe,
802 .remove = spidev_remove,
803
804 /* NOTE: suspend/resume methods are not necessary here.
805 * We don't do anything except pass the requests to/from
806 * the underlying controller. The refrigerator handles
807 * most issues; the controller driver handles the rest.
808 */
809};
810
811/*-------------------------------------------------------------------------*/
812
813static int __init spidev_init(void)
814{
815 int status;
816
817 /* Claim our 256 reserved device numbers. Then register a class
818 * that will key udev/mdev to add/remove /dev nodes. Last, register
819 * the driver which manages those device numbers.
820 */
821 BUILD_BUG_ON(N_SPI_MINORS > 256);
822 status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);
823 if (status < 0)
824 return status;
825
826 spidev_class = class_create(THIS_MODULE, "spidev");
827 if (IS_ERR(spidev_class)) {
828 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
829 return PTR_ERR(spidev_class);
830 }
831
832 status = spi_register_driver(&spidev_spi_driver);
833 if (status < 0) {
834 class_destroy(spidev_class);
835 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
836 }
837 return status;
838}
839module_init(spidev_init);
840
841static void __exit spidev_exit(void)
842{
843 spi_unregister_driver(&spidev_spi_driver);
844 class_destroy(spidev_class);
845 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
846}
847module_exit(spidev_exit);
848
849MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>");
850MODULE_DESCRIPTION("User mode SPI device interface");
851MODULE_LICENSE("GPL");
852MODULE_ALIAS("spi:spidev");