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