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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
33#include <linux/spi/spi.h>
34#include <linux/spi/spidev.h>
35
36#include <linux/uaccess.h>
37
38
39/*
40 * This supports access to SPI devices using normal userspace I/O calls.
41 * Note that while traditional UNIX/POSIX I/O semantics are half duplex,
42 * and often mask message boundaries, full SPI support requires full duplex
43 * transfers. There are several kinds of internal message boundaries to
44 * handle chipselect management and other protocol options.
45 *
46 * SPI has a character major number assigned. We allocate minor numbers
47 * dynamically using a bitmask. You must use hotplug tools, such as udev
48 * (or mdev with busybox) to create and destroy the /dev/spidevB.C device
49 * nodes, since there is no fixed association of minor numbers with any
50 * particular SPI bus or device.
51 */
52#define SPIDEV_MAJOR 153 /* assigned */
53#define N_SPI_MINORS 32 /* ... up to 256 */
54
55static DECLARE_BITMAP(minors, N_SPI_MINORS);
56
57
58/* Bit masks for spi_device.mode management. Note that incorrect
59 * settings for some settings can cause *lots* of trouble for other
60 * devices on a shared bus:
61 *
62 * - CS_HIGH ... this device will be active when it shouldn't be
63 * - 3WIRE ... when active, it won't behave as it should
64 * - NO_CS ... there will be no explicit message boundaries; this
65 * is completely incompatible with the shared bus model
66 * - READY ... transfers may proceed when they shouldn't.
67 *
68 * REVISIT should changing those flags be privileged?
69 */
70#define SPI_MODE_MASK (SPI_CPHA | SPI_CPOL | SPI_CS_HIGH \
71 | SPI_LSB_FIRST | SPI_3WIRE | SPI_LOOP \
72 | SPI_NO_CS | SPI_READY | SPI_TX_DUAL \
73 | SPI_TX_QUAD | SPI_RX_DUAL | SPI_RX_QUAD)
74
75struct spidev_data {
76 dev_t devt;
77 spinlock_t spi_lock;
78 struct spi_device *spi;
79 struct list_head device_entry;
80
81 /* TX/RX buffers are NULL unless this device is open (users > 0) */
82 struct mutex buf_lock;
83 unsigned users;
84 u8 *tx_buffer;
85 u8 *rx_buffer;
86 u32 speed_hz;
87};
88
89static LIST_HEAD(device_list);
90static DEFINE_MUTEX(device_list_lock);
91
92static unsigned bufsiz = 4096;
93module_param(bufsiz, uint, S_IRUGO);
94MODULE_PARM_DESC(bufsiz, "data bytes in biggest supported SPI message");
95
96/*-------------------------------------------------------------------------*/
97
98static ssize_t
99spidev_sync(struct spidev_data *spidev, struct spi_message *message)
100{
101 DECLARE_COMPLETION_ONSTACK(done);
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
120static inline ssize_t
121spidev_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
135static inline ssize_t
136spidev_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 */
153static ssize_t
154spidev_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 */
182static ssize_t
183spidev_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
207static 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 k_tmp->len = u_tmp->len;
236
237 total += k_tmp->len;
238 /* Since the function returns the total length of transfers
239 * on success, restrict the total to positive int values to
240 * avoid the return value looking like an error. Also check
241 * each transfer length to avoid arithmetic overflow.
242 */
243 if (total > INT_MAX || k_tmp->len > INT_MAX) {
244 status = -EMSGSIZE;
245 goto done;
246 }
247
248 if (u_tmp->rx_buf) {
249 /* this transfer needs space in RX bounce buffer */
250 rx_total += k_tmp->len;
251 if (rx_total > bufsiz) {
252 status = -EMSGSIZE;
253 goto done;
254 }
255 k_tmp->rx_buf = rx_buf;
256 if (!access_ok(VERIFY_WRITE, (u8 __user *)
257 (uintptr_t) u_tmp->rx_buf,
258 u_tmp->len))
259 goto done;
260 rx_buf += k_tmp->len;
261 }
262 if (u_tmp->tx_buf) {
263 /* this transfer needs space in TX bounce buffer */
264 tx_total += k_tmp->len;
265 if (tx_total > bufsiz) {
266 status = -EMSGSIZE;
267 goto done;
268 }
269 k_tmp->tx_buf = tx_buf;
270 if (copy_from_user(tx_buf, (const u8 __user *)
271 (uintptr_t) u_tmp->tx_buf,
272 u_tmp->len))
273 goto done;
274 tx_buf += k_tmp->len;
275 }
276
277 k_tmp->cs_change = !!u_tmp->cs_change;
278 k_tmp->tx_nbits = u_tmp->tx_nbits;
279 k_tmp->rx_nbits = u_tmp->rx_nbits;
280 k_tmp->bits_per_word = u_tmp->bits_per_word;
281 k_tmp->delay_usecs = u_tmp->delay_usecs;
282 k_tmp->speed_hz = u_tmp->speed_hz;
283 if (!k_tmp->speed_hz)
284 k_tmp->speed_hz = spidev->speed_hz;
285#ifdef VERBOSE
286 dev_dbg(&spidev->spi->dev,
287 " xfer len %u %s%s%s%dbits %u usec %uHz\n",
288 u_tmp->len,
289 u_tmp->rx_buf ? "rx " : "",
290 u_tmp->tx_buf ? "tx " : "",
291 u_tmp->cs_change ? "cs " : "",
292 u_tmp->bits_per_word ? : spidev->spi->bits_per_word,
293 u_tmp->delay_usecs,
294 u_tmp->speed_hz ? : spidev->spi->max_speed_hz);
295#endif
296 spi_message_add_tail(k_tmp, &msg);
297 }
298
299 status = spidev_sync(spidev, &msg);
300 if (status < 0)
301 goto done;
302
303 /* copy any rx data out of bounce buffer */
304 rx_buf = spidev->rx_buffer;
305 for (n = n_xfers, u_tmp = u_xfers; n; n--, u_tmp++) {
306 if (u_tmp->rx_buf) {
307 if (__copy_to_user((u8 __user *)
308 (uintptr_t) u_tmp->rx_buf, rx_buf,
309 u_tmp->len)) {
310 status = -EFAULT;
311 goto done;
312 }
313 rx_buf += u_tmp->len;
314 }
315 }
316 status = total;
317
318done:
319 kfree(k_xfers);
320 return status;
321}
322
323static struct spi_ioc_transfer *
324spidev_get_ioc_message(unsigned int cmd, struct spi_ioc_transfer __user *u_ioc,
325 unsigned *n_ioc)
326{
327 struct spi_ioc_transfer *ioc;
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 ioc = kmalloc(tmp, GFP_KERNEL);
345 if (!ioc)
346 return ERR_PTR(-ENOMEM);
347 if (__copy_from_user(ioc, u_ioc, tmp)) {
348 kfree(ioc);
349 return ERR_PTR(-EFAULT);
350 }
351 return ioc;
352}
353
354static long
355spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
356{
357 int err = 0;
358 int retval = 0;
359 struct spidev_data *spidev;
360 struct spi_device *spi;
361 u32 tmp;
362 unsigned n_ioc;
363 struct spi_ioc_transfer *ioc;
364
365 /* Check type and command number */
366 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC)
367 return -ENOTTY;
368
369 /* Check access direction once here; don't repeat below.
370 * IOC_DIR is from the user perspective, while access_ok is
371 * from the kernel perspective; so they look reversed.
372 */
373 if (_IOC_DIR(cmd) & _IOC_READ)
374 err = !access_ok(VERIFY_WRITE,
375 (void __user *)arg, _IOC_SIZE(cmd));
376 if (err == 0 && _IOC_DIR(cmd) & _IOC_WRITE)
377 err = !access_ok(VERIFY_READ,
378 (void __user *)arg, _IOC_SIZE(cmd));
379 if (err)
380 return -EFAULT;
381
382 /* guard against device removal before, or while,
383 * we issue this ioctl.
384 */
385 spidev = filp->private_data;
386 spin_lock_irq(&spidev->spi_lock);
387 spi = spi_dev_get(spidev->spi);
388 spin_unlock_irq(&spidev->spi_lock);
389
390 if (spi == NULL)
391 return -ESHUTDOWN;
392
393 /* use the buffer lock here for triple duty:
394 * - prevent I/O (from us) so calling spi_setup() is safe;
395 * - prevent concurrent SPI_IOC_WR_* from morphing
396 * data fields while SPI_IOC_RD_* reads them;
397 * - SPI_IOC_MESSAGE needs the buffer locked "normally".
398 */
399 mutex_lock(&spidev->buf_lock);
400
401 switch (cmd) {
402 /* read requests */
403 case SPI_IOC_RD_MODE:
404 retval = __put_user(spi->mode & SPI_MODE_MASK,
405 (__u8 __user *)arg);
406 break;
407 case SPI_IOC_RD_MODE32:
408 retval = __put_user(spi->mode & SPI_MODE_MASK,
409 (__u32 __user *)arg);
410 break;
411 case SPI_IOC_RD_LSB_FIRST:
412 retval = __put_user((spi->mode & SPI_LSB_FIRST) ? 1 : 0,
413 (__u8 __user *)arg);
414 break;
415 case SPI_IOC_RD_BITS_PER_WORD:
416 retval = __put_user(spi->bits_per_word, (__u8 __user *)arg);
417 break;
418 case SPI_IOC_RD_MAX_SPEED_HZ:
419 retval = __put_user(spidev->speed_hz, (__u32 __user *)arg);
420 break;
421
422 /* write requests */
423 case SPI_IOC_WR_MODE:
424 case SPI_IOC_WR_MODE32:
425 if (cmd == SPI_IOC_WR_MODE)
426 retval = __get_user(tmp, (u8 __user *)arg);
427 else
428 retval = __get_user(tmp, (u32 __user *)arg);
429 if (retval == 0) {
430 u32 save = spi->mode;
431
432 if (tmp & ~SPI_MODE_MASK) {
433 retval = -EINVAL;
434 break;
435 }
436
437 tmp |= spi->mode & ~SPI_MODE_MASK;
438 spi->mode = (u16)tmp;
439 retval = spi_setup(spi);
440 if (retval < 0)
441 spi->mode = save;
442 else
443 dev_dbg(&spi->dev, "spi mode %x\n", tmp);
444 }
445 break;
446 case SPI_IOC_WR_LSB_FIRST:
447 retval = __get_user(tmp, (__u8 __user *)arg);
448 if (retval == 0) {
449 u32 save = spi->mode;
450
451 if (tmp)
452 spi->mode |= SPI_LSB_FIRST;
453 else
454 spi->mode &= ~SPI_LSB_FIRST;
455 retval = spi_setup(spi);
456 if (retval < 0)
457 spi->mode = save;
458 else
459 dev_dbg(&spi->dev, "%csb first\n",
460 tmp ? 'l' : 'm');
461 }
462 break;
463 case SPI_IOC_WR_BITS_PER_WORD:
464 retval = __get_user(tmp, (__u8 __user *)arg);
465 if (retval == 0) {
466 u8 save = spi->bits_per_word;
467
468 spi->bits_per_word = tmp;
469 retval = spi_setup(spi);
470 if (retval < 0)
471 spi->bits_per_word = save;
472 else
473 dev_dbg(&spi->dev, "%d bits per word\n", tmp);
474 }
475 break;
476 case SPI_IOC_WR_MAX_SPEED_HZ:
477 retval = __get_user(tmp, (__u32 __user *)arg);
478 if (retval == 0) {
479 u32 save = spi->max_speed_hz;
480
481 spi->max_speed_hz = tmp;
482 retval = spi_setup(spi);
483 if (retval >= 0)
484 spidev->speed_hz = tmp;
485 else
486 dev_dbg(&spi->dev, "%d Hz (max)\n", tmp);
487 spi->max_speed_hz = save;
488 }
489 break;
490
491 default:
492 /* segmented and/or full-duplex I/O request */
493 /* Check message and copy into scratch area */
494 ioc = spidev_get_ioc_message(cmd,
495 (struct spi_ioc_transfer __user *)arg, &n_ioc);
496 if (IS_ERR(ioc)) {
497 retval = PTR_ERR(ioc);
498 break;
499 }
500 if (!ioc)
501 break; /* n_ioc is also 0 */
502
503 /* translate to spi_message, execute */
504 retval = spidev_message(spidev, ioc, n_ioc);
505 kfree(ioc);
506 break;
507 }
508
509 mutex_unlock(&spidev->buf_lock);
510 spi_dev_put(spi);
511 return retval;
512}
513
514#ifdef CONFIG_COMPAT
515static long
516spidev_compat_ioc_message(struct file *filp, unsigned int cmd,
517 unsigned long arg)
518{
519 struct spi_ioc_transfer __user *u_ioc;
520 int retval = 0;
521 struct spidev_data *spidev;
522 struct spi_device *spi;
523 unsigned n_ioc, n;
524 struct spi_ioc_transfer *ioc;
525
526 u_ioc = (struct spi_ioc_transfer __user *) compat_ptr(arg);
527 if (!access_ok(VERIFY_READ, u_ioc, _IOC_SIZE(cmd)))
528 return -EFAULT;
529
530 /* guard against device removal before, or while,
531 * we issue this ioctl.
532 */
533 spidev = filp->private_data;
534 spin_lock_irq(&spidev->spi_lock);
535 spi = spi_dev_get(spidev->spi);
536 spin_unlock_irq(&spidev->spi_lock);
537
538 if (spi == NULL)
539 return -ESHUTDOWN;
540
541 /* SPI_IOC_MESSAGE needs the buffer locked "normally" */
542 mutex_lock(&spidev->buf_lock);
543
544 /* Check message and copy into scratch area */
545 ioc = spidev_get_ioc_message(cmd, u_ioc, &n_ioc);
546 if (IS_ERR(ioc)) {
547 retval = PTR_ERR(ioc);
548 goto done;
549 }
550 if (!ioc)
551 goto done; /* n_ioc is also 0 */
552
553 /* Convert buffer pointers */
554 for (n = 0; n < n_ioc; n++) {
555 ioc[n].rx_buf = (uintptr_t) compat_ptr(ioc[n].rx_buf);
556 ioc[n].tx_buf = (uintptr_t) compat_ptr(ioc[n].tx_buf);
557 }
558
559 /* translate to spi_message, execute */
560 retval = spidev_message(spidev, ioc, n_ioc);
561 kfree(ioc);
562
563done:
564 mutex_unlock(&spidev->buf_lock);
565 spi_dev_put(spi);
566 return retval;
567}
568
569static long
570spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
571{
572 if (_IOC_TYPE(cmd) == SPI_IOC_MAGIC
573 && _IOC_NR(cmd) == _IOC_NR(SPI_IOC_MESSAGE(0))
574 && _IOC_DIR(cmd) == _IOC_WRITE)
575 return spidev_compat_ioc_message(filp, cmd, arg);
576
577 return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
578}
579#else
580#define spidev_compat_ioctl NULL
581#endif /* CONFIG_COMPAT */
582
583static int spidev_open(struct inode *inode, struct file *filp)
584{
585 struct spidev_data *spidev;
586 int status = -ENXIO;
587
588 mutex_lock(&device_list_lock);
589
590 list_for_each_entry(spidev, &device_list, device_entry) {
591 if (spidev->devt == inode->i_rdev) {
592 status = 0;
593 break;
594 }
595 }
596
597 if (status) {
598 pr_debug("spidev: nothing for minor %d\n", iminor(inode));
599 goto err_find_dev;
600 }
601
602 if (!spidev->tx_buffer) {
603 spidev->tx_buffer = kmalloc(bufsiz, GFP_KERNEL);
604 if (!spidev->tx_buffer) {
605 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
606 status = -ENOMEM;
607 goto err_find_dev;
608 }
609 }
610
611 if (!spidev->rx_buffer) {
612 spidev->rx_buffer = kmalloc(bufsiz, GFP_KERNEL);
613 if (!spidev->rx_buffer) {
614 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
615 status = -ENOMEM;
616 goto err_alloc_rx_buf;
617 }
618 }
619
620 spidev->users++;
621 filp->private_data = spidev;
622 nonseekable_open(inode, filp);
623
624 mutex_unlock(&device_list_lock);
625 return 0;
626
627err_alloc_rx_buf:
628 kfree(spidev->tx_buffer);
629 spidev->tx_buffer = NULL;
630err_find_dev:
631 mutex_unlock(&device_list_lock);
632 return status;
633}
634
635static int spidev_release(struct inode *inode, struct file *filp)
636{
637 struct spidev_data *spidev;
638
639 mutex_lock(&device_list_lock);
640 spidev = filp->private_data;
641 filp->private_data = NULL;
642
643 /* last close? */
644 spidev->users--;
645 if (!spidev->users) {
646 int dofree;
647
648 kfree(spidev->tx_buffer);
649 spidev->tx_buffer = NULL;
650
651 kfree(spidev->rx_buffer);
652 spidev->rx_buffer = NULL;
653
654 spin_lock_irq(&spidev->spi_lock);
655 if (spidev->spi)
656 spidev->speed_hz = spidev->spi->max_speed_hz;
657
658 /* ... after we unbound from the underlying device? */
659 dofree = (spidev->spi == NULL);
660 spin_unlock_irq(&spidev->spi_lock);
661
662 if (dofree)
663 kfree(spidev);
664 }
665 mutex_unlock(&device_list_lock);
666
667 return 0;
668}
669
670static const struct file_operations spidev_fops = {
671 .owner = THIS_MODULE,
672 /* REVISIT switch to aio primitives, so that userspace
673 * gets more complete API coverage. It'll simplify things
674 * too, except for the locking.
675 */
676 .write = spidev_write,
677 .read = spidev_read,
678 .unlocked_ioctl = spidev_ioctl,
679 .compat_ioctl = spidev_compat_ioctl,
680 .open = spidev_open,
681 .release = spidev_release,
682 .llseek = no_llseek,
683};
684
685/*-------------------------------------------------------------------------*/
686
687/* The main reason to have this class is to make mdev/udev create the
688 * /dev/spidevB.C character device nodes exposing our userspace API.
689 * It also simplifies memory management.
690 */
691
692static struct class *spidev_class;
693
694#ifdef CONFIG_OF
695static const struct of_device_id spidev_dt_ids[] = {
696 { .compatible = "rohm,dh2228fv" },
697 { .compatible = "lineartechnology,ltc2488" },
698 {},
699};
700MODULE_DEVICE_TABLE(of, spidev_dt_ids);
701#endif
702
703/*-------------------------------------------------------------------------*/
704
705static int spidev_probe(struct spi_device *spi)
706{
707 struct spidev_data *spidev;
708 int status;
709 unsigned long minor;
710
711 /*
712 * spidev should never be referenced in DT without a specific
713 * compatible string, it is a Linux implementation thing
714 * rather than a description of the hardware.
715 */
716 if (spi->dev.of_node && !of_match_device(spidev_dt_ids, &spi->dev)) {
717 dev_err(&spi->dev, "buggy DT: spidev listed directly in DT\n");
718 WARN_ON(spi->dev.of_node &&
719 !of_match_device(spidev_dt_ids, &spi->dev));
720 }
721
722 /* Allocate driver data */
723 spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);
724 if (!spidev)
725 return -ENOMEM;
726
727 /* Initialize the driver data */
728 spidev->spi = spi;
729 spin_lock_init(&spidev->spi_lock);
730 mutex_init(&spidev->buf_lock);
731
732 INIT_LIST_HEAD(&spidev->device_entry);
733
734 /* If we can allocate a minor number, hook up this device.
735 * Reusing minors is fine so long as udev or mdev is working.
736 */
737 mutex_lock(&device_list_lock);
738 minor = find_first_zero_bit(minors, N_SPI_MINORS);
739 if (minor < N_SPI_MINORS) {
740 struct device *dev;
741
742 spidev->devt = MKDEV(SPIDEV_MAJOR, minor);
743 dev = device_create(spidev_class, &spi->dev, spidev->devt,
744 spidev, "spidev%d.%d",
745 spi->master->bus_num, spi->chip_select);
746 status = PTR_ERR_OR_ZERO(dev);
747 } else {
748 dev_dbg(&spi->dev, "no minor number available!\n");
749 status = -ENODEV;
750 }
751 if (status == 0) {
752 set_bit(minor, minors);
753 list_add(&spidev->device_entry, &device_list);
754 }
755 mutex_unlock(&device_list_lock);
756
757 spidev->speed_hz = spi->max_speed_hz;
758
759 if (status == 0)
760 spi_set_drvdata(spi, spidev);
761 else
762 kfree(spidev);
763
764 return status;
765}
766
767static int spidev_remove(struct spi_device *spi)
768{
769 struct spidev_data *spidev = spi_get_drvdata(spi);
770
771 /* make sure ops on existing fds can abort cleanly */
772 spin_lock_irq(&spidev->spi_lock);
773 spidev->spi = NULL;
774 spin_unlock_irq(&spidev->spi_lock);
775
776 /* prevent new opens */
777 mutex_lock(&device_list_lock);
778 list_del(&spidev->device_entry);
779 device_destroy(spidev_class, spidev->devt);
780 clear_bit(MINOR(spidev->devt), minors);
781 if (spidev->users == 0)
782 kfree(spidev);
783 mutex_unlock(&device_list_lock);
784
785 return 0;
786}
787
788static struct spi_driver spidev_spi_driver = {
789 .driver = {
790 .name = "spidev",
791 .of_match_table = of_match_ptr(spidev_dt_ids),
792 },
793 .probe = spidev_probe,
794 .remove = spidev_remove,
795
796 /* NOTE: suspend/resume methods are not necessary here.
797 * We don't do anything except pass the requests to/from
798 * the underlying controller. The refrigerator handles
799 * most issues; the controller driver handles the rest.
800 */
801};
802
803/*-------------------------------------------------------------------------*/
804
805static int __init spidev_init(void)
806{
807 int status;
808
809 /* Claim our 256 reserved device numbers. Then register a class
810 * that will key udev/mdev to add/remove /dev nodes. Last, register
811 * the driver which manages those device numbers.
812 */
813 BUILD_BUG_ON(N_SPI_MINORS > 256);
814 status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);
815 if (status < 0)
816 return status;
817
818 spidev_class = class_create(THIS_MODULE, "spidev");
819 if (IS_ERR(spidev_class)) {
820 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
821 return PTR_ERR(spidev_class);
822 }
823
824 status = spi_register_driver(&spidev_spi_driver);
825 if (status < 0) {
826 class_destroy(spidev_class);
827 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
828 }
829 return status;
830}
831module_init(spidev_init);
832
833static void __exit spidev_exit(void)
834{
835 spi_unregister_driver(&spidev_spi_driver);
836 class_destroy(spidev_class);
837 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
838}
839module_exit(spidev_exit);
840
841MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>");
842MODULE_DESCRIPTION("User mode SPI device interface");
843MODULE_LICENSE("GPL");
844MODULE_ALIAS("spi:spidev");
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");