blob: 225d6b2f82ddcbc4a4e9031d072e23b2fada88a3 [file] [log] [blame]
Andrea Paterniani814a8d52007-05-08 00:32:15 -07001/*
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
55static 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
62struct 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
72static LIST_HEAD(device_list);
73static DEFINE_MUTEX(device_list_lock);
74
75static unsigned bufsiz = 4096;
76module_param(bufsiz, uint, S_IRUGO);
77MODULE_PARM_DESC(bufsiz, "data bytes in biggest supported SPI message");
78
79/*-------------------------------------------------------------------------*/
80
81/* Read-only message with current device setup */
82static ssize_t
83spidev_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 */
113static ssize_t
114spidev_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
142static 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
171 if (u_tmp->rx_buf) {
172 k_tmp->rx_buf = buf;
173 if (!access_ok(VERIFY_WRITE, u_tmp->rx_buf, u_tmp->len))
174 goto done;
175 }
176 if (u_tmp->tx_buf) {
177 k_tmp->tx_buf = buf;
178 if (copy_from_user(buf, (const u8 __user *)u_tmp->tx_buf,
179 u_tmp->len))
180 goto done;
181 }
182
183 total += k_tmp->len;
184 if (total > bufsiz) {
185 status = -EMSGSIZE;
186 goto done;
187 }
188 buf += k_tmp->len;
189
190 k_tmp->cs_change = !!u_tmp->cs_change;
191 k_tmp->bits_per_word = u_tmp->bits_per_word;
192 k_tmp->delay_usecs = u_tmp->delay_usecs;
193 k_tmp->speed_hz = u_tmp->speed_hz;
194#ifdef VERBOSE
195 dev_dbg(&spi->dev,
196 " xfer len %zd %s%s%s%dbits %u usec %uHz\n",
197 u_tmp->len,
198 u_tmp->rx_buf ? "rx " : "",
199 u_tmp->tx_buf ? "tx " : "",
200 u_tmp->cs_change ? "cs " : "",
201 u_tmp->bits_per_word ? : spi->bits_per_word,
202 u_tmp->delay_usecs,
203 u_tmp->speed_hz ? : spi->max_speed_hz);
204#endif
205 spi_message_add_tail(k_tmp, &msg);
206 }
207
208 status = spi_sync(spi, &msg);
209 if (status < 0)
210 goto done;
211
212 /* copy any rx data out of bounce buffer */
213 buf = spidev->buffer;
214 for (n = n_xfers, u_tmp = u_xfers; n; n--, u_tmp++) {
215 if (u_tmp->rx_buf) {
216 if (__copy_to_user((u8 __user *)u_tmp->rx_buf, buf,
217 u_tmp->len)) {
218 status = -EFAULT;
219 goto done;
220 }
221 }
222 buf += u_tmp->len;
223 }
224 status = total;
225
226done:
227 mutex_unlock(&spidev->buf_lock);
228 kfree(k_xfers);
229 return status;
230}
231
232static int
233spidev_ioctl(struct inode *inode, struct file *filp,
234 unsigned int cmd, unsigned long arg)
235{
236 int err = 0;
237 int retval = 0;
238 struct spidev_data *spidev;
239 struct spi_device *spi;
240 u32 tmp;
241 unsigned n_ioc;
242 struct spi_ioc_transfer *ioc;
243
244 /* Check type and command number */
245 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC)
246 return -ENOTTY;
247
248 /* Check access direction once here; don't repeat below.
249 * IOC_DIR is from the user perspective, while access_ok is
250 * from the kernel perspective; so they look reversed.
251 */
252 if (_IOC_DIR(cmd) & _IOC_READ)
253 err = !access_ok(VERIFY_WRITE,
254 (void __user *)arg, _IOC_SIZE(cmd));
255 if (err == 0 && _IOC_DIR(cmd) & _IOC_WRITE)
256 err = !access_ok(VERIFY_READ,
257 (void __user *)arg, _IOC_SIZE(cmd));
258 if (err)
259 return -EFAULT;
260
261 spidev = filp->private_data;
262 spi = spidev->spi;
263
264 switch (cmd) {
265 /* read requests */
266 case SPI_IOC_RD_MODE:
267 retval = __put_user(spi->mode & SPI_MODE_MASK,
268 (__u8 __user *)arg);
269 break;
270 case SPI_IOC_RD_LSB_FIRST:
271 retval = __put_user((spi->mode & SPI_LSB_FIRST) ? 1 : 0,
272 (__u8 __user *)arg);
273 break;
274 case SPI_IOC_RD_BITS_PER_WORD:
275 retval = __put_user(spi->bits_per_word, (__u8 __user *)arg);
276 break;
277 case SPI_IOC_RD_MAX_SPEED_HZ:
278 retval = __put_user(spi->max_speed_hz, (__u32 __user *)arg);
279 break;
280
281 /* write requests */
282 case SPI_IOC_WR_MODE:
283 retval = __get_user(tmp, (u8 __user *)arg);
284 if (retval == 0) {
285 u8 save = spi->mode;
286
287 if (tmp & ~SPI_MODE_MASK) {
288 retval = -EINVAL;
289 break;
290 }
291
292 tmp |= spi->mode & ~SPI_MODE_MASK;
293 spi->mode = (u8)tmp;
294 retval = spi_setup(spi);
295 if (retval < 0)
296 spi->mode = save;
297 else
298 dev_dbg(&spi->dev, "spi mode %02x\n", tmp);
299 }
300 break;
301 case SPI_IOC_WR_LSB_FIRST:
302 retval = __get_user(tmp, (__u8 __user *)arg);
303 if (retval == 0) {
304 u8 save = spi->mode;
305
306 if (tmp)
307 spi->mode |= SPI_LSB_FIRST;
308 else
309 spi->mode &= ~SPI_LSB_FIRST;
310 retval = spi_setup(spi);
311 if (retval < 0)
312 spi->mode = save;
313 else
314 dev_dbg(&spi->dev, "%csb first\n",
315 tmp ? 'l' : 'm');
316 }
317 break;
318 case SPI_IOC_WR_BITS_PER_WORD:
319 retval = __get_user(tmp, (__u8 __user *)arg);
320 if (retval == 0) {
321 u8 save = spi->bits_per_word;
322
323 spi->bits_per_word = tmp;
324 retval = spi_setup(spi);
325 if (retval < 0)
326 spi->bits_per_word = save;
327 else
328 dev_dbg(&spi->dev, "%d bits per word\n", tmp);
329 }
330 break;
331 case SPI_IOC_WR_MAX_SPEED_HZ:
332 retval = __get_user(tmp, (__u32 __user *)arg);
333 if (retval == 0) {
334 u32 save = spi->max_speed_hz;
335
336 spi->max_speed_hz = tmp;
337 retval = spi_setup(spi);
338 if (retval < 0)
339 spi->max_speed_hz = save;
340 else
341 dev_dbg(&spi->dev, "%d Hz (max)\n", tmp);
342 }
343 break;
344
345 default:
346 /* segmented and/or full-duplex I/O request */
347 if (_IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0))
348 || _IOC_DIR(cmd) != _IOC_WRITE)
349 return -ENOTTY;
350
351 tmp = _IOC_SIZE(cmd);
352 if ((tmp % sizeof(struct spi_ioc_transfer)) != 0) {
353 retval = -EINVAL;
354 break;
355 }
356 n_ioc = tmp / sizeof(struct spi_ioc_transfer);
357 if (n_ioc == 0)
358 break;
359
360 /* copy into scratch area */
361 ioc = kmalloc(tmp, GFP_KERNEL);
362 if (!ioc) {
363 retval = -ENOMEM;
364 break;
365 }
366 if (__copy_from_user(ioc, (void __user *)arg, tmp)) {
367 retval = -EFAULT;
368 break;
369 }
370
371 /* translate to spi_message, execute */
372 retval = spidev_message(spidev, ioc, n_ioc);
373 kfree(ioc);
374 break;
375 }
376 return retval;
377}
378
379static int spidev_open(struct inode *inode, struct file *filp)
380{
381 struct spidev_data *spidev;
382 int status = -ENXIO;
383
384 mutex_lock(&device_list_lock);
385
386 list_for_each_entry(spidev, &device_list, device_entry) {
387 if (spidev->dev.devt == inode->i_rdev) {
388 status = 0;
389 break;
390 }
391 }
392 if (status == 0) {
393 if (!spidev->buffer) {
394 spidev->buffer = kmalloc(bufsiz, GFP_KERNEL);
395 if (!spidev->buffer) {
396 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
397 status = -ENOMEM;
398 }
399 }
400 if (status == 0) {
401 spidev->users++;
402 filp->private_data = spidev;
403 nonseekable_open(inode, filp);
404 }
405 } else
406 pr_debug("spidev: nothing for minor %d\n", iminor(inode));
407
408 mutex_unlock(&device_list_lock);
409 return status;
410}
411
412static int spidev_release(struct inode *inode, struct file *filp)
413{
414 struct spidev_data *spidev;
415 int status = 0;
416
417 mutex_lock(&device_list_lock);
418 spidev = filp->private_data;
419 filp->private_data = NULL;
420 spidev->users--;
421 if (!spidev->users) {
422 kfree(spidev->buffer);
423 spidev->buffer = NULL;
424 }
425 mutex_unlock(&device_list_lock);
426
427 return status;
428}
429
430static struct file_operations spidev_fops = {
431 .owner = THIS_MODULE,
432 /* REVISIT switch to aio primitives, so that userspace
433 * gets more complete API coverage. It'll simplify things
434 * too, except for the locking.
435 */
436 .write = spidev_write,
437 .read = spidev_read,
438 .ioctl = spidev_ioctl,
439 .open = spidev_open,
440 .release = spidev_release,
441};
442
443/*-------------------------------------------------------------------------*/
444
445/* The main reason to have this class is to make mdev/udev create the
446 * /dev/spidevB.C character device nodes exposing our userspace API.
447 * It also simplifies memory management.
448 */
449
450static void spidev_classdev_release(struct device *dev)
451{
452 struct spidev_data *spidev;
453
454 spidev = container_of(dev, struct spidev_data, dev);
455 kfree(spidev);
456}
457
458static struct class spidev_class = {
459 .name = "spidev",
460 .owner = THIS_MODULE,
461 .dev_release = spidev_classdev_release,
462};
463
464/*-------------------------------------------------------------------------*/
465
466static int spidev_probe(struct spi_device *spi)
467{
468 struct spidev_data *spidev;
469 int status;
470 unsigned long minor;
471
472 /* Allocate driver data */
473 spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);
474 if (!spidev)
475 return -ENOMEM;
476
477 /* Initialize the driver data */
478 spidev->spi = spi;
479 mutex_init(&spidev->buf_lock);
480
481 INIT_LIST_HEAD(&spidev->device_entry);
482
483 /* If we can allocate a minor number, hook up this device.
484 * Reusing minors is fine so long as udev or mdev is working.
485 */
486 mutex_lock(&device_list_lock);
Domen Puncer0a4dd772007-05-15 23:57:05 -0700487 minor = find_first_zero_bit(minors, N_SPI_MINORS);
Andrea Paterniani814a8d52007-05-08 00:32:15 -0700488 if (minor < N_SPI_MINORS) {
489 spidev->dev.parent = &spi->dev;
490 spidev->dev.class = &spidev_class;
491 spidev->dev.devt = MKDEV(SPIDEV_MAJOR, minor);
492 snprintf(spidev->dev.bus_id, sizeof spidev->dev.bus_id,
493 "spidev%d.%d",
494 spi->master->bus_num, spi->chip_select);
495 status = device_register(&spidev->dev);
496 } else {
497 dev_dbg(&spi->dev, "no minor number available!\n");
498 status = -ENODEV;
499 }
500 if (status == 0) {
501 set_bit(minor, minors);
502 dev_set_drvdata(&spi->dev, spidev);
503 list_add(&spidev->device_entry, &device_list);
504 }
505 mutex_unlock(&device_list_lock);
506
507 if (status != 0)
508 kfree(spidev);
509
510 return status;
511}
512
513static int spidev_remove(struct spi_device *spi)
514{
515 struct spidev_data *spidev = dev_get_drvdata(&spi->dev);
516
517 mutex_lock(&device_list_lock);
518
519 list_del(&spidev->device_entry);
520 dev_set_drvdata(&spi->dev, NULL);
521 clear_bit(MINOR(spidev->dev.devt), minors);
522 device_unregister(&spidev->dev);
523
524 mutex_unlock(&device_list_lock);
525
526 return 0;
527}
528
529static struct spi_driver spidev_spi = {
530 .driver = {
531 .name = "spidev",
532 .owner = THIS_MODULE,
533 },
534 .probe = spidev_probe,
535 .remove = __devexit_p(spidev_remove),
536
537 /* NOTE: suspend/resume methods are not necessary here.
538 * We don't do anything except pass the requests to/from
539 * the underlying controller. The refrigerator handles
540 * most issues; the controller driver handles the rest.
541 */
542};
543
544/*-------------------------------------------------------------------------*/
545
546static int __init spidev_init(void)
547{
548 int status;
549
550 /* Claim our 256 reserved device numbers. Then register a class
551 * that will key udev/mdev to add/remove /dev nodes. Last, register
552 * the driver which manages those device numbers.
553 */
554 BUILD_BUG_ON(N_SPI_MINORS > 256);
555 status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);
556 if (status < 0)
557 return status;
558
559 status = class_register(&spidev_class);
560 if (status < 0) {
561 unregister_chrdev(SPIDEV_MAJOR, spidev_spi.driver.name);
562 return status;
563 }
564
565 status = spi_register_driver(&spidev_spi);
566 if (status < 0) {
567 class_unregister(&spidev_class);
568 unregister_chrdev(SPIDEV_MAJOR, spidev_spi.driver.name);
569 }
570 return status;
571}
572module_init(spidev_init);
573
574static void __exit spidev_exit(void)
575{
576 spi_unregister_driver(&spidev_spi);
577 class_unregister(&spidev_class);
578 unregister_chrdev(SPIDEV_MAJOR, spidev_spi.driver.name);
579}
580module_exit(spidev_exit);
581
582MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>");
583MODULE_DESCRIPTION("User mode SPI device interface");
584MODULE_LICENSE("GPL");