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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_slave_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 .llseek = no_llseek,
689};
690
691/*-------------------------------------------------------------------------*/
692
693/* The main reason to have this class is to make mdev/udev create the
694 * /dev/spidevB.C character device nodes exposing our userspace API.
695 * It also simplifies memory management.
696 */
697
698static const struct class spidev_class = {
699 .name = "spidev",
700};
701
702static const struct spi_device_id spidev_spi_ids[] = {
703 { .name = "dh2228fv" },
704 { .name = "ltc2488" },
705 { .name = "sx1301" },
706 { .name = "bk4" },
707 { .name = "dhcom-board" },
708 { .name = "m53cpld" },
709 { .name = "spi-petra" },
710 { .name = "spi-authenta" },
711 { .name = "em3581" },
712 { .name = "si3210" },
713 {},
714};
715MODULE_DEVICE_TABLE(spi, spidev_spi_ids);
716
717/*
718 * spidev should never be referenced in DT without a specific compatible string,
719 * it is a Linux implementation thing rather than a description of the hardware.
720 */
721static int spidev_of_check(struct device *dev)
722{
723 if (device_property_match_string(dev, "compatible", "spidev") < 0)
724 return 0;
725
726 dev_err(dev, "spidev listed directly in DT is not supported\n");
727 return -EINVAL;
728}
729
730static const struct of_device_id spidev_dt_ids[] = {
731 { .compatible = "cisco,spi-petra", .data = &spidev_of_check },
732 { .compatible = "dh,dhcom-board", .data = &spidev_of_check },
733 { .compatible = "lineartechnology,ltc2488", .data = &spidev_of_check },
734 { .compatible = "lwn,bk4", .data = &spidev_of_check },
735 { .compatible = "menlo,m53cpld", .data = &spidev_of_check },
736 { .compatible = "micron,spi-authenta", .data = &spidev_of_check },
737 { .compatible = "rohm,dh2228fv", .data = &spidev_of_check },
738 { .compatible = "semtech,sx1301", .data = &spidev_of_check },
739 { .compatible = "silabs,em3581", .data = &spidev_of_check },
740 { .compatible = "silabs,si3210", .data = &spidev_of_check },
741 {},
742};
743MODULE_DEVICE_TABLE(of, spidev_dt_ids);
744
745/* Dummy SPI devices not to be used in production systems */
746static int spidev_acpi_check(struct device *dev)
747{
748 dev_warn(dev, "do not use this driver in production systems!\n");
749 return 0;
750}
751
752static const struct acpi_device_id spidev_acpi_ids[] = {
753 /*
754 * The ACPI SPT000* devices are only meant for development and
755 * testing. Systems used in production should have a proper ACPI
756 * description of the connected peripheral and they should also use
757 * a proper driver instead of poking directly to the SPI bus.
758 */
759 { "SPT0001", (kernel_ulong_t)&spidev_acpi_check },
760 { "SPT0002", (kernel_ulong_t)&spidev_acpi_check },
761 { "SPT0003", (kernel_ulong_t)&spidev_acpi_check },
762 {},
763};
764MODULE_DEVICE_TABLE(acpi, spidev_acpi_ids);
765
766/*-------------------------------------------------------------------------*/
767
768static int spidev_probe(struct spi_device *spi)
769{
770 int (*match)(struct device *dev);
771 struct spidev_data *spidev;
772 int status;
773 unsigned long minor;
774
775 match = device_get_match_data(&spi->dev);
776 if (match) {
777 status = match(&spi->dev);
778 if (status)
779 return status;
780 }
781
782 /* Allocate driver data */
783 spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);
784 if (!spidev)
785 return -ENOMEM;
786
787 /* Initialize the driver data */
788 spidev->spi = spi;
789 mutex_init(&spidev->spi_lock);
790 mutex_init(&spidev->buf_lock);
791
792 INIT_LIST_HEAD(&spidev->device_entry);
793
794 /* If we can allocate a minor number, hook up this device.
795 * Reusing minors is fine so long as udev or mdev is working.
796 */
797 mutex_lock(&device_list_lock);
798 minor = find_first_zero_bit(minors, N_SPI_MINORS);
799 if (minor < N_SPI_MINORS) {
800 struct device *dev;
801
802 spidev->devt = MKDEV(SPIDEV_MAJOR, minor);
803 dev = device_create(&spidev_class, &spi->dev, spidev->devt,
804 spidev, "spidev%d.%d",
805 spi->master->bus_num, spi_get_chipselect(spi, 0));
806 status = PTR_ERR_OR_ZERO(dev);
807 } else {
808 dev_dbg(&spi->dev, "no minor number available!\n");
809 status = -ENODEV;
810 }
811 if (status == 0) {
812 set_bit(minor, minors);
813 list_add(&spidev->device_entry, &device_list);
814 }
815 mutex_unlock(&device_list_lock);
816
817 spidev->speed_hz = spi->max_speed_hz;
818
819 if (status == 0)
820 spi_set_drvdata(spi, spidev);
821 else
822 kfree(spidev);
823
824 return status;
825}
826
827static void spidev_remove(struct spi_device *spi)
828{
829 struct spidev_data *spidev = spi_get_drvdata(spi);
830
831 /* prevent new opens */
832 mutex_lock(&device_list_lock);
833 /* make sure ops on existing fds can abort cleanly */
834 mutex_lock(&spidev->spi_lock);
835 spidev->spi = NULL;
836 mutex_unlock(&spidev->spi_lock);
837
838 list_del(&spidev->device_entry);
839 device_destroy(&spidev_class, spidev->devt);
840 clear_bit(MINOR(spidev->devt), minors);
841 if (spidev->users == 0)
842 kfree(spidev);
843 mutex_unlock(&device_list_lock);
844}
845
846static struct spi_driver spidev_spi_driver = {
847 .driver = {
848 .name = "spidev",
849 .of_match_table = spidev_dt_ids,
850 .acpi_match_table = spidev_acpi_ids,
851 },
852 .probe = spidev_probe,
853 .remove = spidev_remove,
854 .id_table = spidev_spi_ids,
855
856 /* NOTE: suspend/resume methods are not necessary here.
857 * We don't do anything except pass the requests to/from
858 * the underlying controller. The refrigerator handles
859 * most issues; the controller driver handles the rest.
860 */
861};
862
863/*-------------------------------------------------------------------------*/
864
865static int __init spidev_init(void)
866{
867 int status;
868
869 /* Claim our 256 reserved device numbers. Then register a class
870 * that will key udev/mdev to add/remove /dev nodes. Last, register
871 * the driver which manages those device numbers.
872 */
873 status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);
874 if (status < 0)
875 return status;
876
877 status = class_register(&spidev_class);
878 if (status) {
879 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
880 return status;
881 }
882
883 status = spi_register_driver(&spidev_spi_driver);
884 if (status < 0) {
885 class_unregister(&spidev_class);
886 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
887 }
888 return status;
889}
890module_init(spidev_init);
891
892static void __exit spidev_exit(void)
893{
894 spi_unregister_driver(&spidev_spi_driver);
895 class_unregister(&spidev_class);
896 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
897}
898module_exit(spidev_exit);
899
900MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>");
901MODULE_DESCRIPTION("User mode SPI device interface");
902MODULE_LICENSE("GPL");
903MODULE_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 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
21 */
22
23#include <linux/init.h>
24#include <linux/module.h>
25#include <linux/ioctl.h>
26#include <linux/fs.h>
27#include <linux/device.h>
28#include <linux/err.h>
29#include <linux/list.h>
30#include <linux/errno.h>
31#include <linux/mutex.h>
32#include <linux/slab.h>
33#include <linux/compat.h>
34
35#include <linux/spi/spi.h>
36#include <linux/spi/spidev.h>
37
38#include <asm/uaccess.h>
39
40
41/*
42 * This supports access to SPI devices using normal userspace I/O calls.
43 * Note that while traditional UNIX/POSIX I/O semantics are half duplex,
44 * and often mask message boundaries, full SPI support requires full duplex
45 * transfers. There are several kinds of internal message boundaries to
46 * handle chipselect management and other protocol options.
47 *
48 * SPI has a character major number assigned. We allocate minor numbers
49 * dynamically using a bitmask. You must use hotplug tools, such as udev
50 * (or mdev with busybox) to create and destroy the /dev/spidevB.C device
51 * nodes, since there is no fixed association of minor numbers with any
52 * particular SPI bus or device.
53 */
54#define SPIDEV_MAJOR 153 /* assigned */
55#define N_SPI_MINORS 32 /* ... up to 256 */
56
57static DECLARE_BITMAP(minors, N_SPI_MINORS);
58
59
60/* Bit masks for spi_device.mode management. Note that incorrect
61 * settings for some settings can cause *lots* of trouble for other
62 * devices on a shared bus:
63 *
64 * - CS_HIGH ... this device will be active when it shouldn't be
65 * - 3WIRE ... when active, it won't behave as it should
66 * - NO_CS ... there will be no explicit message boundaries; this
67 * is completely incompatible with the shared bus model
68 * - READY ... transfers may proceed when they shouldn't.
69 *
70 * REVISIT should changing those flags be privileged?
71 */
72#define SPI_MODE_MASK (SPI_CPHA | SPI_CPOL | SPI_CS_HIGH \
73 | SPI_LSB_FIRST | SPI_3WIRE | SPI_LOOP \
74 | SPI_NO_CS | SPI_READY)
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 /* buffer is NULL unless this device is open (users > 0) */
83 struct mutex buf_lock;
84 unsigned users;
85 u8 *buffer;
86};
87
88static LIST_HEAD(device_list);
89static DEFINE_MUTEX(device_list_lock);
90
91static unsigned bufsiz = 4096;
92module_param(bufsiz, uint, S_IRUGO);
93MODULE_PARM_DESC(bufsiz, "data bytes in biggest supported SPI message");
94
95/*-------------------------------------------------------------------------*/
96
97/*
98 * We can't use the standard synchronous wrappers for file I/O; we
99 * need to protect against async removal of the underlying spi_device.
100 */
101static void spidev_complete(void *arg)
102{
103 complete(arg);
104}
105
106static ssize_t
107spidev_sync(struct spidev_data *spidev, struct spi_message *message)
108{
109 DECLARE_COMPLETION_ONSTACK(done);
110 int status;
111
112 message->complete = spidev_complete;
113 message->context = &done;
114
115 spin_lock_irq(&spidev->spi_lock);
116 if (spidev->spi == NULL)
117 status = -ESHUTDOWN;
118 else
119 status = spi_async(spidev->spi, message);
120 spin_unlock_irq(&spidev->spi_lock);
121
122 if (status == 0) {
123 wait_for_completion(&done);
124 status = message->status;
125 if (status == 0)
126 status = message->actual_length;
127 }
128 return status;
129}
130
131static inline ssize_t
132spidev_sync_write(struct spidev_data *spidev, size_t len)
133{
134 struct spi_transfer t = {
135 .tx_buf = spidev->buffer,
136 .len = len,
137 };
138 struct spi_message m;
139
140 spi_message_init(&m);
141 spi_message_add_tail(&t, &m);
142 return spidev_sync(spidev, &m);
143}
144
145static inline ssize_t
146spidev_sync_read(struct spidev_data *spidev, size_t len)
147{
148 struct spi_transfer t = {
149 .rx_buf = spidev->buffer,
150 .len = len,
151 };
152 struct spi_message m;
153
154 spi_message_init(&m);
155 spi_message_add_tail(&t, &m);
156 return spidev_sync(spidev, &m);
157}
158
159/*-------------------------------------------------------------------------*/
160
161/* Read-only message with current device setup */
162static ssize_t
163spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
164{
165 struct spidev_data *spidev;
166 ssize_t status = 0;
167
168 /* chipselect only toggles at start or end of operation */
169 if (count > bufsiz)
170 return -EMSGSIZE;
171
172 spidev = filp->private_data;
173
174 mutex_lock(&spidev->buf_lock);
175 status = spidev_sync_read(spidev, count);
176 if (status > 0) {
177 unsigned long missing;
178
179 missing = copy_to_user(buf, spidev->buffer, status);
180 if (missing == status)
181 status = -EFAULT;
182 else
183 status = status - missing;
184 }
185 mutex_unlock(&spidev->buf_lock);
186
187 return status;
188}
189
190/* Write-only message with current device setup */
191static ssize_t
192spidev_write(struct file *filp, const char __user *buf,
193 size_t count, loff_t *f_pos)
194{
195 struct spidev_data *spidev;
196 ssize_t status = 0;
197 unsigned long missing;
198
199 /* chipselect only toggles at start or end of operation */
200 if (count > bufsiz)
201 return -EMSGSIZE;
202
203 spidev = filp->private_data;
204
205 mutex_lock(&spidev->buf_lock);
206 missing = copy_from_user(spidev->buffer, buf, count);
207 if (missing == 0) {
208 status = spidev_sync_write(spidev, count);
209 } else
210 status = -EFAULT;
211 mutex_unlock(&spidev->buf_lock);
212
213 return status;
214}
215
216static int spidev_message(struct spidev_data *spidev,
217 struct spi_ioc_transfer *u_xfers, unsigned n_xfers)
218{
219 struct spi_message msg;
220 struct spi_transfer *k_xfers;
221 struct spi_transfer *k_tmp;
222 struct spi_ioc_transfer *u_tmp;
223 unsigned n, total;
224 u8 *buf;
225 int status = -EFAULT;
226
227 spi_message_init(&msg);
228 k_xfers = kcalloc(n_xfers, sizeof(*k_tmp), GFP_KERNEL);
229 if (k_xfers == NULL)
230 return -ENOMEM;
231
232 /* Construct spi_message, copying any tx data to bounce buffer.
233 * We walk the array of user-provided transfers, using each one
234 * to initialize a kernel version of the same transfer.
235 */
236 buf = spidev->buffer;
237 total = 0;
238 for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers;
239 n;
240 n--, k_tmp++, u_tmp++) {
241 k_tmp->len = u_tmp->len;
242
243 total += k_tmp->len;
244 if (total > bufsiz) {
245 status = -EMSGSIZE;
246 goto done;
247 }
248
249 if (u_tmp->rx_buf) {
250 k_tmp->rx_buf = buf;
251 if (!access_ok(VERIFY_WRITE, (u8 __user *)
252 (uintptr_t) u_tmp->rx_buf,
253 u_tmp->len))
254 goto done;
255 }
256 if (u_tmp->tx_buf) {
257 k_tmp->tx_buf = buf;
258 if (copy_from_user(buf, (const u8 __user *)
259 (uintptr_t) u_tmp->tx_buf,
260 u_tmp->len))
261 goto done;
262 }
263 buf += k_tmp->len;
264
265 k_tmp->cs_change = !!u_tmp->cs_change;
266 k_tmp->bits_per_word = u_tmp->bits_per_word;
267 k_tmp->delay_usecs = u_tmp->delay_usecs;
268 k_tmp->speed_hz = u_tmp->speed_hz;
269#ifdef VERBOSE
270 dev_dbg(&spidev->spi->dev,
271 " xfer len %zd %s%s%s%dbits %u usec %uHz\n",
272 u_tmp->len,
273 u_tmp->rx_buf ? "rx " : "",
274 u_tmp->tx_buf ? "tx " : "",
275 u_tmp->cs_change ? "cs " : "",
276 u_tmp->bits_per_word ? : spidev->spi->bits_per_word,
277 u_tmp->delay_usecs,
278 u_tmp->speed_hz ? : spidev->spi->max_speed_hz);
279#endif
280 spi_message_add_tail(k_tmp, &msg);
281 }
282
283 status = spidev_sync(spidev, &msg);
284 if (status < 0)
285 goto done;
286
287 /* copy any rx data out of bounce buffer */
288 buf = spidev->buffer;
289 for (n = n_xfers, u_tmp = u_xfers; n; n--, u_tmp++) {
290 if (u_tmp->rx_buf) {
291 if (__copy_to_user((u8 __user *)
292 (uintptr_t) u_tmp->rx_buf, buf,
293 u_tmp->len)) {
294 status = -EFAULT;
295 goto done;
296 }
297 }
298 buf += u_tmp->len;
299 }
300 status = total;
301
302done:
303 kfree(k_xfers);
304 return status;
305}
306
307static long
308spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
309{
310 int err = 0;
311 int retval = 0;
312 struct spidev_data *spidev;
313 struct spi_device *spi;
314 u32 tmp;
315 unsigned n_ioc;
316 struct spi_ioc_transfer *ioc;
317
318 /* Check type and command number */
319 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC)
320 return -ENOTTY;
321
322 /* Check access direction once here; don't repeat below.
323 * IOC_DIR is from the user perspective, while access_ok is
324 * from the kernel perspective; so they look reversed.
325 */
326 if (_IOC_DIR(cmd) & _IOC_READ)
327 err = !access_ok(VERIFY_WRITE,
328 (void __user *)arg, _IOC_SIZE(cmd));
329 if (err == 0 && _IOC_DIR(cmd) & _IOC_WRITE)
330 err = !access_ok(VERIFY_READ,
331 (void __user *)arg, _IOC_SIZE(cmd));
332 if (err)
333 return -EFAULT;
334
335 /* guard against device removal before, or while,
336 * we issue this ioctl.
337 */
338 spidev = filp->private_data;
339 spin_lock_irq(&spidev->spi_lock);
340 spi = spi_dev_get(spidev->spi);
341 spin_unlock_irq(&spidev->spi_lock);
342
343 if (spi == NULL)
344 return -ESHUTDOWN;
345
346 /* use the buffer lock here for triple duty:
347 * - prevent I/O (from us) so calling spi_setup() is safe;
348 * - prevent concurrent SPI_IOC_WR_* from morphing
349 * data fields while SPI_IOC_RD_* reads them;
350 * - SPI_IOC_MESSAGE needs the buffer locked "normally".
351 */
352 mutex_lock(&spidev->buf_lock);
353
354 switch (cmd) {
355 /* read requests */
356 case SPI_IOC_RD_MODE:
357 retval = __put_user(spi->mode & SPI_MODE_MASK,
358 (__u8 __user *)arg);
359 break;
360 case SPI_IOC_RD_LSB_FIRST:
361 retval = __put_user((spi->mode & SPI_LSB_FIRST) ? 1 : 0,
362 (__u8 __user *)arg);
363 break;
364 case SPI_IOC_RD_BITS_PER_WORD:
365 retval = __put_user(spi->bits_per_word, (__u8 __user *)arg);
366 break;
367 case SPI_IOC_RD_MAX_SPEED_HZ:
368 retval = __put_user(spi->max_speed_hz, (__u32 __user *)arg);
369 break;
370
371 /* write requests */
372 case SPI_IOC_WR_MODE:
373 retval = __get_user(tmp, (u8 __user *)arg);
374 if (retval == 0) {
375 u8 save = spi->mode;
376
377 if (tmp & ~SPI_MODE_MASK) {
378 retval = -EINVAL;
379 break;
380 }
381
382 tmp |= spi->mode & ~SPI_MODE_MASK;
383 spi->mode = (u8)tmp;
384 retval = spi_setup(spi);
385 if (retval < 0)
386 spi->mode = save;
387 else
388 dev_dbg(&spi->dev, "spi mode %02x\n", tmp);
389 }
390 break;
391 case SPI_IOC_WR_LSB_FIRST:
392 retval = __get_user(tmp, (__u8 __user *)arg);
393 if (retval == 0) {
394 u8 save = spi->mode;
395
396 if (tmp)
397 spi->mode |= SPI_LSB_FIRST;
398 else
399 spi->mode &= ~SPI_LSB_FIRST;
400 retval = spi_setup(spi);
401 if (retval < 0)
402 spi->mode = save;
403 else
404 dev_dbg(&spi->dev, "%csb first\n",
405 tmp ? 'l' : 'm');
406 }
407 break;
408 case SPI_IOC_WR_BITS_PER_WORD:
409 retval = __get_user(tmp, (__u8 __user *)arg);
410 if (retval == 0) {
411 u8 save = spi->bits_per_word;
412
413 spi->bits_per_word = tmp;
414 retval = spi_setup(spi);
415 if (retval < 0)
416 spi->bits_per_word = save;
417 else
418 dev_dbg(&spi->dev, "%d bits per word\n", tmp);
419 }
420 break;
421 case SPI_IOC_WR_MAX_SPEED_HZ:
422 retval = __get_user(tmp, (__u32 __user *)arg);
423 if (retval == 0) {
424 u32 save = spi->max_speed_hz;
425
426 spi->max_speed_hz = tmp;
427 retval = spi_setup(spi);
428 if (retval < 0)
429 spi->max_speed_hz = save;
430 else
431 dev_dbg(&spi->dev, "%d Hz (max)\n", tmp);
432 }
433 break;
434
435 default:
436 /* segmented and/or full-duplex I/O request */
437 if (_IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0))
438 || _IOC_DIR(cmd) != _IOC_WRITE) {
439 retval = -ENOTTY;
440 break;
441 }
442
443 tmp = _IOC_SIZE(cmd);
444 if ((tmp % sizeof(struct spi_ioc_transfer)) != 0) {
445 retval = -EINVAL;
446 break;
447 }
448 n_ioc = tmp / sizeof(struct spi_ioc_transfer);
449 if (n_ioc == 0)
450 break;
451
452 /* copy into scratch area */
453 ioc = kmalloc(tmp, GFP_KERNEL);
454 if (!ioc) {
455 retval = -ENOMEM;
456 break;
457 }
458 if (__copy_from_user(ioc, (void __user *)arg, tmp)) {
459 kfree(ioc);
460 retval = -EFAULT;
461 break;
462 }
463
464 /* translate to spi_message, execute */
465 retval = spidev_message(spidev, ioc, n_ioc);
466 kfree(ioc);
467 break;
468 }
469
470 mutex_unlock(&spidev->buf_lock);
471 spi_dev_put(spi);
472 return retval;
473}
474
475#ifdef CONFIG_COMPAT
476static long
477spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
478{
479 return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
480}
481#else
482#define spidev_compat_ioctl NULL
483#endif /* CONFIG_COMPAT */
484
485static int spidev_open(struct inode *inode, struct file *filp)
486{
487 struct spidev_data *spidev;
488 int status = -ENXIO;
489
490 mutex_lock(&device_list_lock);
491
492 list_for_each_entry(spidev, &device_list, device_entry) {
493 if (spidev->devt == inode->i_rdev) {
494 status = 0;
495 break;
496 }
497 }
498 if (status == 0) {
499 if (!spidev->buffer) {
500 spidev->buffer = kmalloc(bufsiz, GFP_KERNEL);
501 if (!spidev->buffer) {
502 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
503 status = -ENOMEM;
504 }
505 }
506 if (status == 0) {
507 spidev->users++;
508 filp->private_data = spidev;
509 nonseekable_open(inode, filp);
510 }
511 } else
512 pr_debug("spidev: nothing for minor %d\n", iminor(inode));
513
514 mutex_unlock(&device_list_lock);
515 return status;
516}
517
518static int spidev_release(struct inode *inode, struct file *filp)
519{
520 struct spidev_data *spidev;
521 int status = 0;
522
523 mutex_lock(&device_list_lock);
524 spidev = filp->private_data;
525 filp->private_data = NULL;
526
527 /* last close? */
528 spidev->users--;
529 if (!spidev->users) {
530 int dofree;
531
532 kfree(spidev->buffer);
533 spidev->buffer = NULL;
534
535 /* ... after we unbound from the underlying device? */
536 spin_lock_irq(&spidev->spi_lock);
537 dofree = (spidev->spi == NULL);
538 spin_unlock_irq(&spidev->spi_lock);
539
540 if (dofree)
541 kfree(spidev);
542 }
543 mutex_unlock(&device_list_lock);
544
545 return status;
546}
547
548static const struct file_operations spidev_fops = {
549 .owner = THIS_MODULE,
550 /* REVISIT switch to aio primitives, so that userspace
551 * gets more complete API coverage. It'll simplify things
552 * too, except for the locking.
553 */
554 .write = spidev_write,
555 .read = spidev_read,
556 .unlocked_ioctl = spidev_ioctl,
557 .compat_ioctl = spidev_compat_ioctl,
558 .open = spidev_open,
559 .release = spidev_release,
560 .llseek = no_llseek,
561};
562
563/*-------------------------------------------------------------------------*/
564
565/* The main reason to have this class is to make mdev/udev create the
566 * /dev/spidevB.C character device nodes exposing our userspace API.
567 * It also simplifies memory management.
568 */
569
570static struct class *spidev_class;
571
572/*-------------------------------------------------------------------------*/
573
574static int __devinit spidev_probe(struct spi_device *spi)
575{
576 struct spidev_data *spidev;
577 int status;
578 unsigned long minor;
579
580 /* Allocate driver data */
581 spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);
582 if (!spidev)
583 return -ENOMEM;
584
585 /* Initialize the driver data */
586 spidev->spi = spi;
587 spin_lock_init(&spidev->spi_lock);
588 mutex_init(&spidev->buf_lock);
589
590 INIT_LIST_HEAD(&spidev->device_entry);
591
592 /* If we can allocate a minor number, hook up this device.
593 * Reusing minors is fine so long as udev or mdev is working.
594 */
595 mutex_lock(&device_list_lock);
596 minor = find_first_zero_bit(minors, N_SPI_MINORS);
597 if (minor < N_SPI_MINORS) {
598 struct device *dev;
599
600 spidev->devt = MKDEV(SPIDEV_MAJOR, minor);
601 dev = device_create(spidev_class, &spi->dev, spidev->devt,
602 spidev, "spidev%d.%d",
603 spi->master->bus_num, spi->chip_select);
604 status = IS_ERR(dev) ? PTR_ERR(dev) : 0;
605 } else {
606 dev_dbg(&spi->dev, "no minor number available!\n");
607 status = -ENODEV;
608 }
609 if (status == 0) {
610 set_bit(minor, minors);
611 list_add(&spidev->device_entry, &device_list);
612 }
613 mutex_unlock(&device_list_lock);
614
615 if (status == 0)
616 spi_set_drvdata(spi, spidev);
617 else
618 kfree(spidev);
619
620 return status;
621}
622
623static int __devexit spidev_remove(struct spi_device *spi)
624{
625 struct spidev_data *spidev = spi_get_drvdata(spi);
626
627 /* make sure ops on existing fds can abort cleanly */
628 spin_lock_irq(&spidev->spi_lock);
629 spidev->spi = NULL;
630 spi_set_drvdata(spi, NULL);
631 spin_unlock_irq(&spidev->spi_lock);
632
633 /* prevent new opens */
634 mutex_lock(&device_list_lock);
635 list_del(&spidev->device_entry);
636 device_destroy(spidev_class, spidev->devt);
637 clear_bit(MINOR(spidev->devt), minors);
638 if (spidev->users == 0)
639 kfree(spidev);
640 mutex_unlock(&device_list_lock);
641
642 return 0;
643}
644
645static struct spi_driver spidev_spi_driver = {
646 .driver = {
647 .name = "spidev",
648 .owner = THIS_MODULE,
649 },
650 .probe = spidev_probe,
651 .remove = __devexit_p(spidev_remove),
652
653 /* NOTE: suspend/resume methods are not necessary here.
654 * We don't do anything except pass the requests to/from
655 * the underlying controller. The refrigerator handles
656 * most issues; the controller driver handles the rest.
657 */
658};
659
660/*-------------------------------------------------------------------------*/
661
662static int __init spidev_init(void)
663{
664 int status;
665
666 /* Claim our 256 reserved device numbers. Then register a class
667 * that will key udev/mdev to add/remove /dev nodes. Last, register
668 * the driver which manages those device numbers.
669 */
670 BUILD_BUG_ON(N_SPI_MINORS > 256);
671 status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);
672 if (status < 0)
673 return status;
674
675 spidev_class = class_create(THIS_MODULE, "spidev");
676 if (IS_ERR(spidev_class)) {
677 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
678 return PTR_ERR(spidev_class);
679 }
680
681 status = spi_register_driver(&spidev_spi_driver);
682 if (status < 0) {
683 class_destroy(spidev_class);
684 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
685 }
686 return status;
687}
688module_init(spidev_init);
689
690static void __exit spidev_exit(void)
691{
692 spi_unregister_driver(&spidev_spi_driver);
693 class_destroy(spidev_class);
694 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
695}
696module_exit(spidev_exit);
697
698MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>");
699MODULE_DESCRIPTION("User mode SPI device interface");
700MODULE_LICENSE("GPL");
701MODULE_ALIAS("spi:spidev");