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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Simple synchronous userspace interface to SPI devices
4 *
5 * Copyright (C) 2006 SWAPP
6 * Andrea Paterniani <a.paterniani@swapp-eng.it>
7 * Copyright (C) 2007 David Brownell (simplification, cleanup)
8 */
9
10#include <linux/init.h>
11#include <linux/ioctl.h>
12#include <linux/fs.h>
13#include <linux/device.h>
14#include <linux/err.h>
15#include <linux/list.h>
16#include <linux/errno.h>
17#include <linux/mod_devicetable.h>
18#include <linux/module.h>
19#include <linux/mutex.h>
20#include <linux/property.h>
21#include <linux/slab.h>
22#include <linux/compat.h>
23
24#include <linux/spi/spi.h>
25#include <linux/spi/spidev.h>
26
27#include <linux/uaccess.h>
28
29
30/*
31 * This supports access to SPI devices using normal userspace I/O calls.
32 * Note that while traditional UNIX/POSIX I/O semantics are half duplex,
33 * and often mask message boundaries, full SPI support requires full duplex
34 * transfers. There are several kinds of internal message boundaries to
35 * handle chipselect management and other protocol options.
36 *
37 * SPI has a character major number assigned. We allocate minor numbers
38 * dynamically using a bitmask. You must use hotplug tools, such as udev
39 * (or mdev with busybox) to create and destroy the /dev/spidevB.C device
40 * nodes, since there is no fixed association of minor numbers with any
41 * particular SPI bus or device.
42 */
43#define SPIDEV_MAJOR 153 /* assigned */
44#define N_SPI_MINORS 32 /* ... up to 256 */
45
46static DECLARE_BITMAP(minors, N_SPI_MINORS);
47
48static_assert(N_SPI_MINORS > 0 && N_SPI_MINORS <= 256);
49
50/* Bit masks for spi_device.mode management. Note that incorrect
51 * settings for some settings can cause *lots* of trouble for other
52 * devices on a shared bus:
53 *
54 * - CS_HIGH ... this device will be active when it shouldn't be
55 * - 3WIRE ... when active, it won't behave as it should
56 * - NO_CS ... there will be no explicit message boundaries; this
57 * is completely incompatible with the shared bus model
58 * - READY ... transfers may proceed when they shouldn't.
59 *
60 * REVISIT should changing those flags be privileged?
61 */
62#define SPI_MODE_MASK (SPI_MODE_X_MASK | SPI_CS_HIGH \
63 | SPI_LSB_FIRST | SPI_3WIRE | SPI_LOOP \
64 | SPI_NO_CS | SPI_READY | SPI_TX_DUAL \
65 | SPI_TX_QUAD | SPI_TX_OCTAL | SPI_RX_DUAL \
66 | SPI_RX_QUAD | SPI_RX_OCTAL \
67 | SPI_RX_CPHA_FLIP | SPI_3WIRE_HIZ \
68 | SPI_MOSI_IDLE_LOW)
69
70struct spidev_data {
71 dev_t devt;
72 struct mutex spi_lock;
73 struct spi_device *spi;
74 struct list_head device_entry;
75
76 /* TX/RX buffers are NULL unless this device is open (users > 0) */
77 struct mutex buf_lock;
78 unsigned users;
79 u8 *tx_buffer;
80 u8 *rx_buffer;
81 u32 speed_hz;
82};
83
84static LIST_HEAD(device_list);
85static DEFINE_MUTEX(device_list_lock);
86
87static unsigned bufsiz = 4096;
88module_param(bufsiz, uint, S_IRUGO);
89MODULE_PARM_DESC(bufsiz, "data bytes in biggest supported SPI message");
90
91/*-------------------------------------------------------------------------*/
92
93static ssize_t
94spidev_sync_unlocked(struct spi_device *spi, struct spi_message *message)
95{
96 ssize_t status;
97
98 status = spi_sync(spi, message);
99 if (status == 0)
100 status = message->actual_length;
101
102 return status;
103}
104
105static ssize_t
106spidev_sync(struct spidev_data *spidev, struct spi_message *message)
107{
108 ssize_t status;
109 struct spi_device *spi;
110
111 mutex_lock(&spidev->spi_lock);
112 spi = spidev->spi;
113
114 if (spi == NULL)
115 status = -ESHUTDOWN;
116 else
117 status = spidev_sync_unlocked(spi, message);
118
119 mutex_unlock(&spidev->spi_lock);
120 return status;
121}
122
123static inline ssize_t
124spidev_sync_write(struct spidev_data *spidev, size_t len)
125{
126 struct spi_transfer t = {
127 .tx_buf = spidev->tx_buffer,
128 .len = len,
129 .speed_hz = spidev->speed_hz,
130 };
131 struct spi_message m;
132
133 spi_message_init(&m);
134 spi_message_add_tail(&t, &m);
135 return spidev_sync(spidev, &m);
136}
137
138static inline ssize_t
139spidev_sync_read(struct spidev_data *spidev, size_t len)
140{
141 struct spi_transfer t = {
142 .rx_buf = spidev->rx_buffer,
143 .len = len,
144 .speed_hz = spidev->speed_hz,
145 };
146 struct spi_message m;
147
148 spi_message_init(&m);
149 spi_message_add_tail(&t, &m);
150 return spidev_sync(spidev, &m);
151}
152
153/*-------------------------------------------------------------------------*/
154
155/* Read-only message with current device setup */
156static ssize_t
157spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
158{
159 struct spidev_data *spidev;
160 ssize_t status;
161
162 /* chipselect only toggles at start or end of operation */
163 if (count > bufsiz)
164 return -EMSGSIZE;
165
166 spidev = filp->private_data;
167
168 mutex_lock(&spidev->buf_lock);
169 status = spidev_sync_read(spidev, count);
170 if (status > 0) {
171 unsigned long missing;
172
173 missing = copy_to_user(buf, spidev->rx_buffer, status);
174 if (missing == status)
175 status = -EFAULT;
176 else
177 status = status - missing;
178 }
179 mutex_unlock(&spidev->buf_lock);
180
181 return status;
182}
183
184/* Write-only message with current device setup */
185static ssize_t
186spidev_write(struct file *filp, const char __user *buf,
187 size_t count, loff_t *f_pos)
188{
189 struct spidev_data *spidev;
190 ssize_t status;
191 unsigned long missing;
192
193 /* chipselect only toggles at start or end of operation */
194 if (count > bufsiz)
195 return -EMSGSIZE;
196
197 spidev = filp->private_data;
198
199 mutex_lock(&spidev->buf_lock);
200 missing = copy_from_user(spidev->tx_buffer, buf, count);
201 if (missing == 0)
202 status = spidev_sync_write(spidev, count);
203 else
204 status = -EFAULT;
205 mutex_unlock(&spidev->buf_lock);
206
207 return status;
208}
209
210static int spidev_message(struct spidev_data *spidev,
211 struct spi_ioc_transfer *u_xfers, unsigned n_xfers)
212{
213 struct spi_message msg;
214 struct spi_transfer *k_xfers;
215 struct spi_transfer *k_tmp;
216 struct spi_ioc_transfer *u_tmp;
217 unsigned n, total, tx_total, rx_total;
218 u8 *tx_buf, *rx_buf;
219 int status = -EFAULT;
220
221 spi_message_init(&msg);
222 k_xfers = kcalloc(n_xfers, sizeof(*k_tmp), GFP_KERNEL);
223 if (k_xfers == NULL)
224 return -ENOMEM;
225
226 /* Construct spi_message, copying any tx data to bounce buffer.
227 * We walk the array of user-provided transfers, using each one
228 * to initialize a kernel version of the same transfer.
229 */
230 tx_buf = spidev->tx_buffer;
231 rx_buf = spidev->rx_buffer;
232 total = 0;
233 tx_total = 0;
234 rx_total = 0;
235 for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers;
236 n;
237 n--, k_tmp++, u_tmp++) {
238 /* Ensure that also following allocations from rx_buf/tx_buf will meet
239 * DMA alignment requirements.
240 */
241 unsigned int len_aligned = ALIGN(u_tmp->len, ARCH_DMA_MINALIGN);
242
243 k_tmp->len = u_tmp->len;
244
245 total += k_tmp->len;
246 /* Since the function returns the total length of transfers
247 * on success, restrict the total to positive int values to
248 * avoid the return value looking like an error. Also check
249 * each transfer length to avoid arithmetic overflow.
250 */
251 if (total > INT_MAX || k_tmp->len > INT_MAX) {
252 status = -EMSGSIZE;
253 goto done;
254 }
255
256 if (u_tmp->rx_buf) {
257 /* this transfer needs space in RX bounce buffer */
258 rx_total += len_aligned;
259 if (rx_total > bufsiz) {
260 status = -EMSGSIZE;
261 goto done;
262 }
263 k_tmp->rx_buf = rx_buf;
264 rx_buf += len_aligned;
265 }
266 if (u_tmp->tx_buf) {
267 /* this transfer needs space in TX bounce buffer */
268 tx_total += len_aligned;
269 if (tx_total > bufsiz) {
270 status = -EMSGSIZE;
271 goto done;
272 }
273 k_tmp->tx_buf = tx_buf;
274 if (copy_from_user(tx_buf, (const u8 __user *)
275 (uintptr_t) u_tmp->tx_buf,
276 u_tmp->len))
277 goto done;
278 tx_buf += len_aligned;
279 }
280
281 k_tmp->cs_change = !!u_tmp->cs_change;
282 k_tmp->tx_nbits = u_tmp->tx_nbits;
283 k_tmp->rx_nbits = u_tmp->rx_nbits;
284 k_tmp->bits_per_word = u_tmp->bits_per_word;
285 k_tmp->delay.value = u_tmp->delay_usecs;
286 k_tmp->delay.unit = SPI_DELAY_UNIT_USECS;
287 k_tmp->speed_hz = u_tmp->speed_hz;
288 k_tmp->word_delay.value = u_tmp->word_delay_usecs;
289 k_tmp->word_delay.unit = SPI_DELAY_UNIT_USECS;
290 if (!k_tmp->speed_hz)
291 k_tmp->speed_hz = spidev->speed_hz;
292#ifdef VERBOSE
293 dev_dbg(&spidev->spi->dev,
294 " xfer len %u %s%s%s%dbits %u usec %u usec %uHz\n",
295 k_tmp->len,
296 k_tmp->rx_buf ? "rx " : "",
297 k_tmp->tx_buf ? "tx " : "",
298 k_tmp->cs_change ? "cs " : "",
299 k_tmp->bits_per_word ? : spidev->spi->bits_per_word,
300 k_tmp->delay.value,
301 k_tmp->word_delay.value,
302 k_tmp->speed_hz ? : spidev->spi->max_speed_hz);
303#endif
304 spi_message_add_tail(k_tmp, &msg);
305 }
306
307 status = spidev_sync_unlocked(spidev->spi, &msg);
308 if (status < 0)
309 goto done;
310
311 /* copy any rx data out of bounce buffer */
312 for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers;
313 n;
314 n--, k_tmp++, u_tmp++) {
315 if (u_tmp->rx_buf) {
316 if (copy_to_user((u8 __user *)
317 (uintptr_t) u_tmp->rx_buf, k_tmp->rx_buf,
318 u_tmp->len)) {
319 status = -EFAULT;
320 goto done;
321 }
322 }
323 }
324 status = total;
325
326done:
327 kfree(k_xfers);
328 return status;
329}
330
331static struct spi_ioc_transfer *
332spidev_get_ioc_message(unsigned int cmd, struct spi_ioc_transfer __user *u_ioc,
333 unsigned *n_ioc)
334{
335 u32 tmp;
336
337 /* Check type, command number and direction */
338 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC
339 || _IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0))
340 || _IOC_DIR(cmd) != _IOC_WRITE)
341 return ERR_PTR(-ENOTTY);
342
343 tmp = _IOC_SIZE(cmd);
344 if ((tmp % sizeof(struct spi_ioc_transfer)) != 0)
345 return ERR_PTR(-EINVAL);
346 *n_ioc = tmp / sizeof(struct spi_ioc_transfer);
347 if (*n_ioc == 0)
348 return NULL;
349
350 /* copy into scratch area */
351 return memdup_user(u_ioc, tmp);
352}
353
354static long
355spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
356{
357 int retval = 0;
358 struct spidev_data *spidev;
359 struct spi_device *spi;
360 struct spi_controller *ctlr;
361 u32 tmp;
362 unsigned n_ioc;
363 struct spi_ioc_transfer *ioc;
364
365 /* Check type and command number */
366 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC)
367 return -ENOTTY;
368
369 /* guard against device removal before, or while,
370 * we issue this ioctl.
371 */
372 spidev = filp->private_data;
373 mutex_lock(&spidev->spi_lock);
374 spi = spi_dev_get(spidev->spi);
375 if (spi == NULL) {
376 mutex_unlock(&spidev->spi_lock);
377 return -ESHUTDOWN;
378 }
379
380 ctlr = spi->controller;
381
382 /* use the buffer lock here for triple duty:
383 * - prevent I/O (from us) so calling spi_setup() is safe;
384 * - prevent concurrent SPI_IOC_WR_* from morphing
385 * data fields while SPI_IOC_RD_* reads them;
386 * - SPI_IOC_MESSAGE needs the buffer locked "normally".
387 */
388 mutex_lock(&spidev->buf_lock);
389
390 switch (cmd) {
391 /* read requests */
392 case SPI_IOC_RD_MODE:
393 case SPI_IOC_RD_MODE32:
394 tmp = spi->mode & SPI_MODE_MASK;
395
396 if (ctlr->use_gpio_descriptors && spi_get_csgpiod(spi, 0))
397 tmp &= ~SPI_CS_HIGH;
398
399 if (cmd == SPI_IOC_RD_MODE)
400 retval = put_user(tmp, (__u8 __user *)arg);
401 else
402 retval = put_user(tmp, (__u32 __user *)arg);
403 break;
404 case SPI_IOC_RD_LSB_FIRST:
405 retval = put_user((spi->mode & SPI_LSB_FIRST) ? 1 : 0,
406 (__u8 __user *)arg);
407 break;
408 case SPI_IOC_RD_BITS_PER_WORD:
409 retval = put_user(spi->bits_per_word, (__u8 __user *)arg);
410 break;
411 case SPI_IOC_RD_MAX_SPEED_HZ:
412 retval = put_user(spidev->speed_hz, (__u32 __user *)arg);
413 break;
414
415 /* write requests */
416 case SPI_IOC_WR_MODE:
417 case SPI_IOC_WR_MODE32:
418 if (cmd == SPI_IOC_WR_MODE)
419 retval = get_user(tmp, (u8 __user *)arg);
420 else
421 retval = get_user(tmp, (u32 __user *)arg);
422 if (retval == 0) {
423 u32 save = spi->mode;
424
425 if (tmp & ~SPI_MODE_MASK) {
426 retval = -EINVAL;
427 break;
428 }
429
430 if (ctlr->use_gpio_descriptors && spi_get_csgpiod(spi, 0))
431 tmp |= SPI_CS_HIGH;
432
433 tmp |= spi->mode & ~SPI_MODE_MASK;
434 spi->mode = tmp & SPI_MODE_USER_MASK;
435 retval = spi_setup(spi);
436 if (retval < 0)
437 spi->mode = save;
438 else
439 dev_dbg(&spi->dev, "spi mode %x\n", tmp);
440 }
441 break;
442 case SPI_IOC_WR_LSB_FIRST:
443 retval = get_user(tmp, (__u8 __user *)arg);
444 if (retval == 0) {
445 u32 save = spi->mode;
446
447 if (tmp)
448 spi->mode |= SPI_LSB_FIRST;
449 else
450 spi->mode &= ~SPI_LSB_FIRST;
451 retval = spi_setup(spi);
452 if (retval < 0)
453 spi->mode = save;
454 else
455 dev_dbg(&spi->dev, "%csb first\n",
456 tmp ? 'l' : 'm');
457 }
458 break;
459 case SPI_IOC_WR_BITS_PER_WORD:
460 retval = get_user(tmp, (__u8 __user *)arg);
461 if (retval == 0) {
462 u8 save = spi->bits_per_word;
463
464 spi->bits_per_word = tmp;
465 retval = spi_setup(spi);
466 if (retval < 0)
467 spi->bits_per_word = save;
468 else
469 dev_dbg(&spi->dev, "%d bits per word\n", tmp);
470 }
471 break;
472 case SPI_IOC_WR_MAX_SPEED_HZ: {
473 u32 save;
474
475 retval = get_user(tmp, (__u32 __user *)arg);
476 if (retval)
477 break;
478 if (tmp == 0) {
479 retval = -EINVAL;
480 break;
481 }
482
483 save = spi->max_speed_hz;
484
485 spi->max_speed_hz = tmp;
486 retval = spi_setup(spi);
487 if (retval == 0) {
488 spidev->speed_hz = tmp;
489 dev_dbg(&spi->dev, "%d Hz (max)\n", spidev->speed_hz);
490 }
491
492 spi->max_speed_hz = save;
493 break;
494 }
495 default:
496 /* segmented and/or full-duplex I/O request */
497 /* Check message and copy into scratch area */
498 ioc = spidev_get_ioc_message(cmd,
499 (struct spi_ioc_transfer __user *)arg, &n_ioc);
500 if (IS_ERR(ioc)) {
501 retval = PTR_ERR(ioc);
502 break;
503 }
504 if (!ioc)
505 break; /* n_ioc is also 0 */
506
507 /* translate to spi_message, execute */
508 retval = spidev_message(spidev, ioc, n_ioc);
509 kfree(ioc);
510 break;
511 }
512
513 mutex_unlock(&spidev->buf_lock);
514 spi_dev_put(spi);
515 mutex_unlock(&spidev->spi_lock);
516 return retval;
517}
518
519#ifdef CONFIG_COMPAT
520static long
521spidev_compat_ioc_message(struct file *filp, unsigned int cmd,
522 unsigned long arg)
523{
524 struct spi_ioc_transfer __user *u_ioc;
525 int retval = 0;
526 struct spidev_data *spidev;
527 struct spi_device *spi;
528 unsigned n_ioc, n;
529 struct spi_ioc_transfer *ioc;
530
531 u_ioc = (struct spi_ioc_transfer __user *) compat_ptr(arg);
532
533 /* guard against device removal before, or while,
534 * we issue this ioctl.
535 */
536 spidev = filp->private_data;
537 mutex_lock(&spidev->spi_lock);
538 spi = spi_dev_get(spidev->spi);
539 if (spi == NULL) {
540 mutex_unlock(&spidev->spi_lock);
541 return -ESHUTDOWN;
542 }
543
544 /* SPI_IOC_MESSAGE needs the buffer locked "normally" */
545 mutex_lock(&spidev->buf_lock);
546
547 /* Check message and copy into scratch area */
548 ioc = spidev_get_ioc_message(cmd, u_ioc, &n_ioc);
549 if (IS_ERR(ioc)) {
550 retval = PTR_ERR(ioc);
551 goto done;
552 }
553 if (!ioc)
554 goto done; /* n_ioc is also 0 */
555
556 /* Convert buffer pointers */
557 for (n = 0; n < n_ioc; n++) {
558 ioc[n].rx_buf = (uintptr_t) compat_ptr(ioc[n].rx_buf);
559 ioc[n].tx_buf = (uintptr_t) compat_ptr(ioc[n].tx_buf);
560 }
561
562 /* translate to spi_message, execute */
563 retval = spidev_message(spidev, ioc, n_ioc);
564 kfree(ioc);
565
566done:
567 mutex_unlock(&spidev->buf_lock);
568 spi_dev_put(spi);
569 mutex_unlock(&spidev->spi_lock);
570 return retval;
571}
572
573static long
574spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
575{
576 if (_IOC_TYPE(cmd) == SPI_IOC_MAGIC
577 && _IOC_NR(cmd) == _IOC_NR(SPI_IOC_MESSAGE(0))
578 && _IOC_DIR(cmd) == _IOC_WRITE)
579 return spidev_compat_ioc_message(filp, cmd, arg);
580
581 return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
582}
583#else
584#define spidev_compat_ioctl NULL
585#endif /* CONFIG_COMPAT */
586
587static int spidev_open(struct inode *inode, struct file *filp)
588{
589 struct spidev_data *spidev = NULL, *iter;
590 int status = -ENXIO;
591
592 mutex_lock(&device_list_lock);
593
594 list_for_each_entry(iter, &device_list, device_entry) {
595 if (iter->devt == inode->i_rdev) {
596 status = 0;
597 spidev = iter;
598 break;
599 }
600 }
601
602 if (!spidev) {
603 pr_debug("spidev: nothing for minor %d\n", iminor(inode));
604 goto err_find_dev;
605 }
606
607 if (!spidev->tx_buffer) {
608 spidev->tx_buffer = kmalloc(bufsiz, GFP_KERNEL);
609 if (!spidev->tx_buffer) {
610 status = -ENOMEM;
611 goto err_find_dev;
612 }
613 }
614
615 if (!spidev->rx_buffer) {
616 spidev->rx_buffer = kmalloc(bufsiz, GFP_KERNEL);
617 if (!spidev->rx_buffer) {
618 status = -ENOMEM;
619 goto err_alloc_rx_buf;
620 }
621 }
622
623 spidev->users++;
624 filp->private_data = spidev;
625 stream_open(inode, filp);
626
627 mutex_unlock(&device_list_lock);
628 return 0;
629
630err_alloc_rx_buf:
631 kfree(spidev->tx_buffer);
632 spidev->tx_buffer = NULL;
633err_find_dev:
634 mutex_unlock(&device_list_lock);
635 return status;
636}
637
638static int spidev_release(struct inode *inode, struct file *filp)
639{
640 struct spidev_data *spidev;
641 int dofree;
642
643 mutex_lock(&device_list_lock);
644 spidev = filp->private_data;
645 filp->private_data = NULL;
646
647 mutex_lock(&spidev->spi_lock);
648 /* ... after we unbound from the underlying device? */
649 dofree = (spidev->spi == NULL);
650 mutex_unlock(&spidev->spi_lock);
651
652 /* last close? */
653 spidev->users--;
654 if (!spidev->users) {
655
656 kfree(spidev->tx_buffer);
657 spidev->tx_buffer = NULL;
658
659 kfree(spidev->rx_buffer);
660 spidev->rx_buffer = NULL;
661
662 if (dofree)
663 kfree(spidev);
664 else
665 spidev->speed_hz = spidev->spi->max_speed_hz;
666 }
667#ifdef CONFIG_SPI_SLAVE
668 if (!dofree)
669 spi_target_abort(spidev->spi);
670#endif
671 mutex_unlock(&device_list_lock);
672
673 return 0;
674}
675
676static const struct file_operations spidev_fops = {
677 .owner = THIS_MODULE,
678 /* REVISIT switch to aio primitives, so that userspace
679 * gets more complete API coverage. It'll simplify things
680 * too, except for the locking.
681 */
682 .write = spidev_write,
683 .read = spidev_read,
684 .unlocked_ioctl = spidev_ioctl,
685 .compat_ioctl = spidev_compat_ioctl,
686 .open = spidev_open,
687 .release = spidev_release,
688};
689
690/*-------------------------------------------------------------------------*/
691
692/* The main reason to have this class is to make mdev/udev create the
693 * /dev/spidevB.C character device nodes exposing our userspace API.
694 * It also simplifies memory management.
695 */
696
697static const struct class spidev_class = {
698 .name = "spidev",
699};
700
701static const struct spi_device_id spidev_spi_ids[] = {
702 { .name = "bh2228fv" },
703 { .name = "dh2228fv" },
704 { .name = "jg10309-01" },
705 { .name = "ltc2488" },
706 { .name = "sx1301" },
707 { .name = "bk4" },
708 { .name = "dhcom-board" },
709 { .name = "m53cpld" },
710 { .name = "spi-petra" },
711 { .name = "spi-authenta" },
712 { .name = "em3581" },
713 { .name = "si3210" },
714 {},
715};
716MODULE_DEVICE_TABLE(spi, spidev_spi_ids);
717
718/*
719 * spidev should never be referenced in DT without a specific compatible string,
720 * it is a Linux implementation thing rather than a description of the hardware.
721 */
722static int spidev_of_check(struct device *dev)
723{
724 if (device_property_match_string(dev, "compatible", "spidev") < 0)
725 return 0;
726
727 dev_err(dev, "spidev listed directly in DT is not supported\n");
728 return -EINVAL;
729}
730
731static const struct of_device_id spidev_dt_ids[] = {
732 { .compatible = "cisco,spi-petra", .data = &spidev_of_check },
733 { .compatible = "dh,dhcom-board", .data = &spidev_of_check },
734 { .compatible = "elgin,jg10309-01", .data = &spidev_of_check },
735 { .compatible = "lineartechnology,ltc2488", .data = &spidev_of_check },
736 { .compatible = "lwn,bk4", .data = &spidev_of_check },
737 { .compatible = "menlo,m53cpld", .data = &spidev_of_check },
738 { .compatible = "micron,spi-authenta", .data = &spidev_of_check },
739 { .compatible = "rohm,bh2228fv", .data = &spidev_of_check },
740 { .compatible = "rohm,dh2228fv", .data = &spidev_of_check },
741 { .compatible = "semtech,sx1301", .data = &spidev_of_check },
742 { .compatible = "silabs,em3581", .data = &spidev_of_check },
743 { .compatible = "silabs,si3210", .data = &spidev_of_check },
744 {},
745};
746MODULE_DEVICE_TABLE(of, spidev_dt_ids);
747
748/* Dummy SPI devices not to be used in production systems */
749static int spidev_acpi_check(struct device *dev)
750{
751 dev_warn(dev, "do not use this driver in production systems!\n");
752 return 0;
753}
754
755static const struct acpi_device_id spidev_acpi_ids[] = {
756 /*
757 * The ACPI SPT000* devices are only meant for development and
758 * testing. Systems used in production should have a proper ACPI
759 * description of the connected peripheral and they should also use
760 * a proper driver instead of poking directly to the SPI bus.
761 */
762 { "SPT0001", (kernel_ulong_t)&spidev_acpi_check },
763 { "SPT0002", (kernel_ulong_t)&spidev_acpi_check },
764 { "SPT0003", (kernel_ulong_t)&spidev_acpi_check },
765 {},
766};
767MODULE_DEVICE_TABLE(acpi, spidev_acpi_ids);
768
769/*-------------------------------------------------------------------------*/
770
771static int spidev_probe(struct spi_device *spi)
772{
773 int (*match)(struct device *dev);
774 struct spidev_data *spidev;
775 int status;
776 unsigned long minor;
777
778 match = device_get_match_data(&spi->dev);
779 if (match) {
780 status = match(&spi->dev);
781 if (status)
782 return status;
783 }
784
785 /* Allocate driver data */
786 spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);
787 if (!spidev)
788 return -ENOMEM;
789
790 /* Initialize the driver data */
791 spidev->spi = spi;
792 mutex_init(&spidev->spi_lock);
793 mutex_init(&spidev->buf_lock);
794
795 INIT_LIST_HEAD(&spidev->device_entry);
796
797 /* If we can allocate a minor number, hook up this device.
798 * Reusing minors is fine so long as udev or mdev is working.
799 */
800 mutex_lock(&device_list_lock);
801 minor = find_first_zero_bit(minors, N_SPI_MINORS);
802 if (minor < N_SPI_MINORS) {
803 struct device *dev;
804
805 spidev->devt = MKDEV(SPIDEV_MAJOR, minor);
806 dev = device_create(&spidev_class, &spi->dev, spidev->devt,
807 spidev, "spidev%d.%d",
808 spi->controller->bus_num, spi_get_chipselect(spi, 0));
809 status = PTR_ERR_OR_ZERO(dev);
810 } else {
811 dev_dbg(&spi->dev, "no minor number available!\n");
812 status = -ENODEV;
813 }
814 if (status == 0) {
815 set_bit(minor, minors);
816 list_add(&spidev->device_entry, &device_list);
817 }
818 mutex_unlock(&device_list_lock);
819
820 spidev->speed_hz = spi->max_speed_hz;
821
822 if (status == 0)
823 spi_set_drvdata(spi, spidev);
824 else
825 kfree(spidev);
826
827 return status;
828}
829
830static void spidev_remove(struct spi_device *spi)
831{
832 struct spidev_data *spidev = spi_get_drvdata(spi);
833
834 /* prevent new opens */
835 mutex_lock(&device_list_lock);
836 /* make sure ops on existing fds can abort cleanly */
837 mutex_lock(&spidev->spi_lock);
838 spidev->spi = NULL;
839 mutex_unlock(&spidev->spi_lock);
840
841 list_del(&spidev->device_entry);
842 device_destroy(&spidev_class, spidev->devt);
843 clear_bit(MINOR(spidev->devt), minors);
844 if (spidev->users == 0)
845 kfree(spidev);
846 mutex_unlock(&device_list_lock);
847}
848
849static struct spi_driver spidev_spi_driver = {
850 .driver = {
851 .name = "spidev",
852 .of_match_table = spidev_dt_ids,
853 .acpi_match_table = spidev_acpi_ids,
854 },
855 .probe = spidev_probe,
856 .remove = spidev_remove,
857 .id_table = spidev_spi_ids,
858
859 /* NOTE: suspend/resume methods are not necessary here.
860 * We don't do anything except pass the requests to/from
861 * the underlying controller. The refrigerator handles
862 * most issues; the controller driver handles the rest.
863 */
864};
865
866/*-------------------------------------------------------------------------*/
867
868static int __init spidev_init(void)
869{
870 int status;
871
872 /* Claim our 256 reserved device numbers. Then register a class
873 * that will key udev/mdev to add/remove /dev nodes. Last, register
874 * the driver which manages those device numbers.
875 */
876 status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);
877 if (status < 0)
878 return status;
879
880 status = class_register(&spidev_class);
881 if (status) {
882 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
883 return status;
884 }
885
886 status = spi_register_driver(&spidev_spi_driver);
887 if (status < 0) {
888 class_unregister(&spidev_class);
889 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
890 }
891 return status;
892}
893module_init(spidev_init);
894
895static void __exit spidev_exit(void)
896{
897 spi_unregister_driver(&spidev_spi_driver);
898 class_unregister(&spidev_class);
899 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
900}
901module_exit(spidev_exit);
902
903MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>");
904MODULE_DESCRIPTION("User mode SPI device interface");
905MODULE_LICENSE("GPL");
906MODULE_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");