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814a8d50 AP |
1 | /* |
2 | * spidev.c -- 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/list.h> | |
29 | #include <linux/errno.h> | |
30 | #include <linux/mutex.h> | |
31 | #include <linux/slab.h> | |
32 | ||
33 | #include <linux/spi/spi.h> | |
34 | #include <linux/spi/spidev.h> | |
35 | ||
36 | #include <asm/uaccess.h> | |
37 | ||
38 | ||
39 | /* | |
40 | * This supports acccess to SPI devices using normal userspace I/O calls. | |
41 | * Note that while traditional UNIX/POSIX I/O semantics are half duplex, | |
42 | * and often mask message boundaries, full SPI support requires full duplex | |
43 | * transfers. There are several kinds of of internal message boundaries to | |
44 | * handle chipselect management and other protocol options. | |
45 | * | |
46 | * SPI has a character major number assigned. We allocate minor numbers | |
47 | * dynamically using a bitmask. You must use hotplug tools, such as udev | |
48 | * (or mdev with busybox) to create and destroy the /dev/spidevB.C device | |
49 | * nodes, since there is no fixed association of minor numbers with any | |
50 | * particular SPI bus or device. | |
51 | */ | |
52 | #define SPIDEV_MAJOR 153 /* assigned */ | |
53 | #define N_SPI_MINORS 32 /* ... up to 256 */ | |
54 | ||
55 | static unsigned long minors[N_SPI_MINORS / BITS_PER_LONG]; | |
56 | ||
57 | ||
58 | /* Bit masks for spi_device.mode management */ | |
59 | #define SPI_MODE_MASK (SPI_CPHA | SPI_CPOL) | |
60 | ||
61 | ||
62 | struct spidev_data { | |
63 | struct device dev; | |
64 | struct spi_device *spi; | |
65 | struct list_head device_entry; | |
66 | ||
67 | struct mutex buf_lock; | |
68 | unsigned users; | |
69 | u8 *buffer; | |
70 | }; | |
71 | ||
72 | static LIST_HEAD(device_list); | |
73 | static DEFINE_MUTEX(device_list_lock); | |
74 | ||
75 | static unsigned bufsiz = 4096; | |
76 | module_param(bufsiz, uint, S_IRUGO); | |
77 | MODULE_PARM_DESC(bufsiz, "data bytes in biggest supported SPI message"); | |
78 | ||
79 | /*-------------------------------------------------------------------------*/ | |
80 | ||
81 | /* Read-only message with current device setup */ | |
82 | static ssize_t | |
83 | spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos) | |
84 | { | |
85 | struct spidev_data *spidev; | |
86 | struct spi_device *spi; | |
87 | ssize_t status = 0; | |
88 | ||
89 | /* chipselect only toggles at start or end of operation */ | |
90 | if (count > bufsiz) | |
91 | return -EMSGSIZE; | |
92 | ||
93 | spidev = filp->private_data; | |
94 | spi = spidev->spi; | |
95 | ||
96 | mutex_lock(&spidev->buf_lock); | |
97 | status = spi_read(spi, spidev->buffer, count); | |
98 | if (status == 0) { | |
99 | unsigned long missing; | |
100 | ||
101 | missing = copy_to_user(buf, spidev->buffer, count); | |
102 | if (count && missing == count) | |
103 | status = -EFAULT; | |
104 | else | |
105 | status = count - missing; | |
106 | } | |
107 | mutex_unlock(&spidev->buf_lock); | |
108 | ||
109 | return status; | |
110 | } | |
111 | ||
112 | /* Write-only message with current device setup */ | |
113 | static ssize_t | |
114 | spidev_write(struct file *filp, const char __user *buf, | |
115 | size_t count, loff_t *f_pos) | |
116 | { | |
117 | struct spidev_data *spidev; | |
118 | struct spi_device *spi; | |
119 | ssize_t status = 0; | |
120 | unsigned long missing; | |
121 | ||
122 | /* chipselect only toggles at start or end of operation */ | |
123 | if (count > bufsiz) | |
124 | return -EMSGSIZE; | |
125 | ||
126 | spidev = filp->private_data; | |
127 | spi = spidev->spi; | |
128 | ||
129 | mutex_lock(&spidev->buf_lock); | |
130 | missing = copy_from_user(spidev->buffer, buf, count); | |
131 | if (missing == 0) { | |
132 | status = spi_write(spi, spidev->buffer, count); | |
133 | if (status == 0) | |
134 | status = count; | |
135 | } else | |
136 | status = -EFAULT; | |
137 | mutex_unlock(&spidev->buf_lock); | |
138 | ||
139 | return status; | |
140 | } | |
141 | ||
142 | static int spidev_message(struct spidev_data *spidev, | |
143 | struct spi_ioc_transfer *u_xfers, unsigned n_xfers) | |
144 | { | |
145 | struct spi_message msg; | |
146 | struct spi_transfer *k_xfers; | |
147 | struct spi_transfer *k_tmp; | |
148 | struct spi_ioc_transfer *u_tmp; | |
149 | struct spi_device *spi = spidev->spi; | |
150 | unsigned n, total; | |
151 | u8 *buf; | |
152 | int status = -EFAULT; | |
153 | ||
154 | spi_message_init(&msg); | |
155 | k_xfers = kcalloc(n_xfers, sizeof(*k_tmp), GFP_KERNEL); | |
156 | if (k_xfers == NULL) | |
157 | return -ENOMEM; | |
158 | ||
159 | /* Construct spi_message, copying any tx data to bounce buffer. | |
160 | * We walk the array of user-provided transfers, using each one | |
161 | * to initialize a kernel version of the same transfer. | |
162 | */ | |
163 | mutex_lock(&spidev->buf_lock); | |
164 | buf = spidev->buffer; | |
165 | total = 0; | |
166 | for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers; | |
167 | n; | |
168 | n--, k_tmp++, u_tmp++) { | |
169 | k_tmp->len = u_tmp->len; | |
170 | ||
da90fa8f DP |
171 | total += k_tmp->len; |
172 | if (total > bufsiz) { | |
173 | status = -EMSGSIZE; | |
174 | goto done; | |
175 | } | |
176 | ||
814a8d50 AP |
177 | if (u_tmp->rx_buf) { |
178 | k_tmp->rx_buf = buf; | |
179 | if (!access_ok(VERIFY_WRITE, u_tmp->rx_buf, u_tmp->len)) | |
180 | goto done; | |
181 | } | |
182 | if (u_tmp->tx_buf) { | |
183 | k_tmp->tx_buf = buf; | |
4917d927 DB |
184 | if (copy_from_user(buf, (const u8 __user *) |
185 | (ptrdiff_t) u_tmp->tx_buf, | |
814a8d50 AP |
186 | u_tmp->len)) |
187 | goto done; | |
188 | } | |
814a8d50 AP |
189 | buf += k_tmp->len; |
190 | ||
191 | k_tmp->cs_change = !!u_tmp->cs_change; | |
192 | k_tmp->bits_per_word = u_tmp->bits_per_word; | |
193 | k_tmp->delay_usecs = u_tmp->delay_usecs; | |
194 | k_tmp->speed_hz = u_tmp->speed_hz; | |
195 | #ifdef VERBOSE | |
196 | dev_dbg(&spi->dev, | |
197 | " xfer len %zd %s%s%s%dbits %u usec %uHz\n", | |
198 | u_tmp->len, | |
199 | u_tmp->rx_buf ? "rx " : "", | |
200 | u_tmp->tx_buf ? "tx " : "", | |
201 | u_tmp->cs_change ? "cs " : "", | |
202 | u_tmp->bits_per_word ? : spi->bits_per_word, | |
203 | u_tmp->delay_usecs, | |
204 | u_tmp->speed_hz ? : spi->max_speed_hz); | |
205 | #endif | |
206 | spi_message_add_tail(k_tmp, &msg); | |
207 | } | |
208 | ||
209 | status = spi_sync(spi, &msg); | |
210 | if (status < 0) | |
211 | goto done; | |
212 | ||
213 | /* copy any rx data out of bounce buffer */ | |
214 | buf = spidev->buffer; | |
215 | for (n = n_xfers, u_tmp = u_xfers; n; n--, u_tmp++) { | |
216 | if (u_tmp->rx_buf) { | |
4917d927 DB |
217 | if (__copy_to_user((u8 __user *) |
218 | (ptrdiff_t) u_tmp->rx_buf, buf, | |
814a8d50 AP |
219 | u_tmp->len)) { |
220 | status = -EFAULT; | |
221 | goto done; | |
222 | } | |
223 | } | |
224 | buf += u_tmp->len; | |
225 | } | |
226 | status = total; | |
227 | ||
228 | done: | |
229 | mutex_unlock(&spidev->buf_lock); | |
230 | kfree(k_xfers); | |
231 | return status; | |
232 | } | |
233 | ||
234 | static int | |
235 | spidev_ioctl(struct inode *inode, struct file *filp, | |
236 | unsigned int cmd, unsigned long arg) | |
237 | { | |
238 | int err = 0; | |
239 | int retval = 0; | |
240 | struct spidev_data *spidev; | |
241 | struct spi_device *spi; | |
242 | u32 tmp; | |
243 | unsigned n_ioc; | |
244 | struct spi_ioc_transfer *ioc; | |
245 | ||
246 | /* Check type and command number */ | |
247 | if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC) | |
248 | return -ENOTTY; | |
249 | ||
250 | /* Check access direction once here; don't repeat below. | |
251 | * IOC_DIR is from the user perspective, while access_ok is | |
252 | * from the kernel perspective; so they look reversed. | |
253 | */ | |
254 | if (_IOC_DIR(cmd) & _IOC_READ) | |
255 | err = !access_ok(VERIFY_WRITE, | |
256 | (void __user *)arg, _IOC_SIZE(cmd)); | |
257 | if (err == 0 && _IOC_DIR(cmd) & _IOC_WRITE) | |
258 | err = !access_ok(VERIFY_READ, | |
259 | (void __user *)arg, _IOC_SIZE(cmd)); | |
260 | if (err) | |
261 | return -EFAULT; | |
262 | ||
263 | spidev = filp->private_data; | |
264 | spi = spidev->spi; | |
265 | ||
266 | switch (cmd) { | |
267 | /* read requests */ | |
268 | case SPI_IOC_RD_MODE: | |
269 | retval = __put_user(spi->mode & SPI_MODE_MASK, | |
270 | (__u8 __user *)arg); | |
271 | break; | |
272 | case SPI_IOC_RD_LSB_FIRST: | |
273 | retval = __put_user((spi->mode & SPI_LSB_FIRST) ? 1 : 0, | |
274 | (__u8 __user *)arg); | |
275 | break; | |
276 | case SPI_IOC_RD_BITS_PER_WORD: | |
277 | retval = __put_user(spi->bits_per_word, (__u8 __user *)arg); | |
278 | break; | |
279 | case SPI_IOC_RD_MAX_SPEED_HZ: | |
280 | retval = __put_user(spi->max_speed_hz, (__u32 __user *)arg); | |
281 | break; | |
282 | ||
283 | /* write requests */ | |
284 | case SPI_IOC_WR_MODE: | |
285 | retval = __get_user(tmp, (u8 __user *)arg); | |
286 | if (retval == 0) { | |
287 | u8 save = spi->mode; | |
288 | ||
289 | if (tmp & ~SPI_MODE_MASK) { | |
290 | retval = -EINVAL; | |
291 | break; | |
292 | } | |
293 | ||
294 | tmp |= spi->mode & ~SPI_MODE_MASK; | |
295 | spi->mode = (u8)tmp; | |
296 | retval = spi_setup(spi); | |
297 | if (retval < 0) | |
298 | spi->mode = save; | |
299 | else | |
300 | dev_dbg(&spi->dev, "spi mode %02x\n", tmp); | |
301 | } | |
302 | break; | |
303 | case SPI_IOC_WR_LSB_FIRST: | |
304 | retval = __get_user(tmp, (__u8 __user *)arg); | |
305 | if (retval == 0) { | |
306 | u8 save = spi->mode; | |
307 | ||
308 | if (tmp) | |
309 | spi->mode |= SPI_LSB_FIRST; | |
310 | else | |
311 | spi->mode &= ~SPI_LSB_FIRST; | |
312 | retval = spi_setup(spi); | |
313 | if (retval < 0) | |
314 | spi->mode = save; | |
315 | else | |
316 | dev_dbg(&spi->dev, "%csb first\n", | |
317 | tmp ? 'l' : 'm'); | |
318 | } | |
319 | break; | |
320 | case SPI_IOC_WR_BITS_PER_WORD: | |
321 | retval = __get_user(tmp, (__u8 __user *)arg); | |
322 | if (retval == 0) { | |
323 | u8 save = spi->bits_per_word; | |
324 | ||
325 | spi->bits_per_word = tmp; | |
326 | retval = spi_setup(spi); | |
327 | if (retval < 0) | |
328 | spi->bits_per_word = save; | |
329 | else | |
330 | dev_dbg(&spi->dev, "%d bits per word\n", tmp); | |
331 | } | |
332 | break; | |
333 | case SPI_IOC_WR_MAX_SPEED_HZ: | |
334 | retval = __get_user(tmp, (__u32 __user *)arg); | |
335 | if (retval == 0) { | |
336 | u32 save = spi->max_speed_hz; | |
337 | ||
338 | spi->max_speed_hz = tmp; | |
339 | retval = spi_setup(spi); | |
340 | if (retval < 0) | |
341 | spi->max_speed_hz = save; | |
342 | else | |
343 | dev_dbg(&spi->dev, "%d Hz (max)\n", tmp); | |
344 | } | |
345 | break; | |
346 | ||
347 | default: | |
348 | /* segmented and/or full-duplex I/O request */ | |
349 | if (_IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0)) | |
350 | || _IOC_DIR(cmd) != _IOC_WRITE) | |
351 | return -ENOTTY; | |
352 | ||
353 | tmp = _IOC_SIZE(cmd); | |
354 | if ((tmp % sizeof(struct spi_ioc_transfer)) != 0) { | |
355 | retval = -EINVAL; | |
356 | break; | |
357 | } | |
358 | n_ioc = tmp / sizeof(struct spi_ioc_transfer); | |
359 | if (n_ioc == 0) | |
360 | break; | |
361 | ||
362 | /* copy into scratch area */ | |
363 | ioc = kmalloc(tmp, GFP_KERNEL); | |
364 | if (!ioc) { | |
365 | retval = -ENOMEM; | |
366 | break; | |
367 | } | |
368 | if (__copy_from_user(ioc, (void __user *)arg, tmp)) { | |
9bea3f29 | 369 | kfree(ioc); |
814a8d50 AP |
370 | retval = -EFAULT; |
371 | break; | |
372 | } | |
373 | ||
374 | /* translate to spi_message, execute */ | |
375 | retval = spidev_message(spidev, ioc, n_ioc); | |
376 | kfree(ioc); | |
377 | break; | |
378 | } | |
379 | return retval; | |
380 | } | |
381 | ||
382 | static int spidev_open(struct inode *inode, struct file *filp) | |
383 | { | |
384 | struct spidev_data *spidev; | |
385 | int status = -ENXIO; | |
386 | ||
387 | mutex_lock(&device_list_lock); | |
388 | ||
389 | list_for_each_entry(spidev, &device_list, device_entry) { | |
390 | if (spidev->dev.devt == inode->i_rdev) { | |
391 | status = 0; | |
392 | break; | |
393 | } | |
394 | } | |
395 | if (status == 0) { | |
396 | if (!spidev->buffer) { | |
397 | spidev->buffer = kmalloc(bufsiz, GFP_KERNEL); | |
398 | if (!spidev->buffer) { | |
399 | dev_dbg(&spidev->spi->dev, "open/ENOMEM\n"); | |
400 | status = -ENOMEM; | |
401 | } | |
402 | } | |
403 | if (status == 0) { | |
404 | spidev->users++; | |
405 | filp->private_data = spidev; | |
406 | nonseekable_open(inode, filp); | |
407 | } | |
408 | } else | |
409 | pr_debug("spidev: nothing for minor %d\n", iminor(inode)); | |
410 | ||
411 | mutex_unlock(&device_list_lock); | |
412 | return status; | |
413 | } | |
414 | ||
415 | static int spidev_release(struct inode *inode, struct file *filp) | |
416 | { | |
417 | struct spidev_data *spidev; | |
418 | int status = 0; | |
419 | ||
420 | mutex_lock(&device_list_lock); | |
421 | spidev = filp->private_data; | |
422 | filp->private_data = NULL; | |
423 | spidev->users--; | |
424 | if (!spidev->users) { | |
425 | kfree(spidev->buffer); | |
426 | spidev->buffer = NULL; | |
427 | } | |
428 | mutex_unlock(&device_list_lock); | |
429 | ||
430 | return status; | |
431 | } | |
432 | ||
433 | static struct file_operations spidev_fops = { | |
434 | .owner = THIS_MODULE, | |
435 | /* REVISIT switch to aio primitives, so that userspace | |
436 | * gets more complete API coverage. It'll simplify things | |
437 | * too, except for the locking. | |
438 | */ | |
439 | .write = spidev_write, | |
440 | .read = spidev_read, | |
441 | .ioctl = spidev_ioctl, | |
442 | .open = spidev_open, | |
443 | .release = spidev_release, | |
444 | }; | |
445 | ||
446 | /*-------------------------------------------------------------------------*/ | |
447 | ||
448 | /* The main reason to have this class is to make mdev/udev create the | |
449 | * /dev/spidevB.C character device nodes exposing our userspace API. | |
450 | * It also simplifies memory management. | |
451 | */ | |
452 | ||
453 | static void spidev_classdev_release(struct device *dev) | |
454 | { | |
455 | struct spidev_data *spidev; | |
456 | ||
457 | spidev = container_of(dev, struct spidev_data, dev); | |
458 | kfree(spidev); | |
459 | } | |
460 | ||
461 | static struct class spidev_class = { | |
462 | .name = "spidev", | |
463 | .owner = THIS_MODULE, | |
464 | .dev_release = spidev_classdev_release, | |
465 | }; | |
466 | ||
467 | /*-------------------------------------------------------------------------*/ | |
468 | ||
469 | static int spidev_probe(struct spi_device *spi) | |
470 | { | |
471 | struct spidev_data *spidev; | |
472 | int status; | |
473 | unsigned long minor; | |
474 | ||
475 | /* Allocate driver data */ | |
476 | spidev = kzalloc(sizeof(*spidev), GFP_KERNEL); | |
477 | if (!spidev) | |
478 | return -ENOMEM; | |
479 | ||
480 | /* Initialize the driver data */ | |
481 | spidev->spi = spi; | |
482 | mutex_init(&spidev->buf_lock); | |
483 | ||
484 | INIT_LIST_HEAD(&spidev->device_entry); | |
485 | ||
486 | /* If we can allocate a minor number, hook up this device. | |
487 | * Reusing minors is fine so long as udev or mdev is working. | |
488 | */ | |
489 | mutex_lock(&device_list_lock); | |
0a4dd778 | 490 | minor = find_first_zero_bit(minors, N_SPI_MINORS); |
814a8d50 AP |
491 | if (minor < N_SPI_MINORS) { |
492 | spidev->dev.parent = &spi->dev; | |
493 | spidev->dev.class = &spidev_class; | |
494 | spidev->dev.devt = MKDEV(SPIDEV_MAJOR, minor); | |
495 | snprintf(spidev->dev.bus_id, sizeof spidev->dev.bus_id, | |
496 | "spidev%d.%d", | |
497 | spi->master->bus_num, spi->chip_select); | |
498 | status = device_register(&spidev->dev); | |
499 | } else { | |
500 | dev_dbg(&spi->dev, "no minor number available!\n"); | |
501 | status = -ENODEV; | |
502 | } | |
503 | if (status == 0) { | |
504 | set_bit(minor, minors); | |
505 | dev_set_drvdata(&spi->dev, spidev); | |
506 | list_add(&spidev->device_entry, &device_list); | |
507 | } | |
508 | mutex_unlock(&device_list_lock); | |
509 | ||
510 | if (status != 0) | |
511 | kfree(spidev); | |
512 | ||
513 | return status; | |
514 | } | |
515 | ||
516 | static int spidev_remove(struct spi_device *spi) | |
517 | { | |
518 | struct spidev_data *spidev = dev_get_drvdata(&spi->dev); | |
519 | ||
520 | mutex_lock(&device_list_lock); | |
521 | ||
522 | list_del(&spidev->device_entry); | |
523 | dev_set_drvdata(&spi->dev, NULL); | |
524 | clear_bit(MINOR(spidev->dev.devt), minors); | |
525 | device_unregister(&spidev->dev); | |
526 | ||
527 | mutex_unlock(&device_list_lock); | |
528 | ||
529 | return 0; | |
530 | } | |
531 | ||
532 | static struct spi_driver spidev_spi = { | |
533 | .driver = { | |
534 | .name = "spidev", | |
535 | .owner = THIS_MODULE, | |
536 | }, | |
537 | .probe = spidev_probe, | |
538 | .remove = __devexit_p(spidev_remove), | |
539 | ||
540 | /* NOTE: suspend/resume methods are not necessary here. | |
541 | * We don't do anything except pass the requests to/from | |
542 | * the underlying controller. The refrigerator handles | |
543 | * most issues; the controller driver handles the rest. | |
544 | */ | |
545 | }; | |
546 | ||
547 | /*-------------------------------------------------------------------------*/ | |
548 | ||
549 | static int __init spidev_init(void) | |
550 | { | |
551 | int status; | |
552 | ||
553 | /* Claim our 256 reserved device numbers. Then register a class | |
554 | * that will key udev/mdev to add/remove /dev nodes. Last, register | |
555 | * the driver which manages those device numbers. | |
556 | */ | |
557 | BUILD_BUG_ON(N_SPI_MINORS > 256); | |
558 | status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops); | |
559 | if (status < 0) | |
560 | return status; | |
561 | ||
562 | status = class_register(&spidev_class); | |
563 | if (status < 0) { | |
564 | unregister_chrdev(SPIDEV_MAJOR, spidev_spi.driver.name); | |
565 | return status; | |
566 | } | |
567 | ||
568 | status = spi_register_driver(&spidev_spi); | |
569 | if (status < 0) { | |
570 | class_unregister(&spidev_class); | |
571 | unregister_chrdev(SPIDEV_MAJOR, spidev_spi.driver.name); | |
572 | } | |
573 | return status; | |
574 | } | |
575 | module_init(spidev_init); | |
576 | ||
577 | static void __exit spidev_exit(void) | |
578 | { | |
579 | spi_unregister_driver(&spidev_spi); | |
580 | class_unregister(&spidev_class); | |
581 | unregister_chrdev(SPIDEV_MAJOR, spidev_spi.driver.name); | |
582 | } | |
583 | module_exit(spidev_exit); | |
584 | ||
585 | MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>"); | |
586 | MODULE_DESCRIPTION("User mode SPI device interface"); | |
587 | MODULE_LICENSE("GPL"); |