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