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