Linux 3.3-rc6
[linux/fpc-iii.git] / drivers / spi / spidev.c
blob830adbed1d7ace083697312cf4ed585606c4a35b
1 /*
2 * Simple synchronous userspace interface to SPI devices
4 * Copyright (C) 2006 SWAPP
5 * Andrea Paterniani <a.paterniani@swapp-eng.it>
6 * Copyright (C) 2007 David Brownell (simplification, cleanup)
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.
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.
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.
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>
35 #include <linux/spi/spi.h>
36 #include <linux/spi/spidev.h>
38 #include <asm/uaccess.h>
42 * This supports access to SPI devices using normal userspace I/O calls.
43 * Note that while traditional UNIX/POSIX I/O semantics are half duplex,
44 * and often mask message boundaries, full SPI support requires full duplex
45 * transfers. There are several kinds of internal message boundaries to
46 * handle chipselect management and other protocol options.
48 * SPI has a character major number assigned. We allocate minor numbers
49 * dynamically using a bitmask. You must use hotplug tools, such as udev
50 * (or mdev with busybox) to create and destroy the /dev/spidevB.C device
51 * nodes, since there is no fixed association of minor numbers with any
52 * particular SPI bus or device.
54 #define SPIDEV_MAJOR 153 /* assigned */
55 #define N_SPI_MINORS 32 /* ... up to 256 */
57 static DECLARE_BITMAP(minors, N_SPI_MINORS);
60 /* Bit masks for spi_device.mode management. Note that incorrect
61 * settings for some settings can cause *lots* of trouble for other
62 * devices on a shared bus:
64 * - CS_HIGH ... this device will be active when it shouldn't be
65 * - 3WIRE ... when active, it won't behave as it should
66 * - NO_CS ... there will be no explicit message boundaries; this
67 * is completely incompatible with the shared bus model
68 * - READY ... transfers may proceed when they shouldn't.
70 * REVISIT should changing those flags be privileged?
72 #define SPI_MODE_MASK (SPI_CPHA | SPI_CPOL | SPI_CS_HIGH \
73 | SPI_LSB_FIRST | SPI_3WIRE | SPI_LOOP \
74 | SPI_NO_CS | SPI_READY)
76 struct spidev_data {
77 dev_t devt;
78 spinlock_t spi_lock;
79 struct spi_device *spi;
80 struct list_head device_entry;
82 /* buffer is NULL unless this device is open (users > 0) */
83 struct mutex buf_lock;
84 unsigned users;
85 u8 *buffer;
88 static LIST_HEAD(device_list);
89 static DEFINE_MUTEX(device_list_lock);
91 static unsigned bufsiz = 4096;
92 module_param(bufsiz, uint, S_IRUGO);
93 MODULE_PARM_DESC(bufsiz, "data bytes in biggest supported SPI message");
95 /*-------------------------------------------------------------------------*/
98 * We can't use the standard synchronous wrappers for file I/O; we
99 * need to protect against async removal of the underlying spi_device.
101 static void spidev_complete(void *arg)
103 complete(arg);
106 static ssize_t
107 spidev_sync(struct spidev_data *spidev, struct spi_message *message)
109 DECLARE_COMPLETION_ONSTACK(done);
110 int status;
112 message->complete = spidev_complete;
113 message->context = &done;
115 spin_lock_irq(&spidev->spi_lock);
116 if (spidev->spi == NULL)
117 status = -ESHUTDOWN;
118 else
119 status = spi_async(spidev->spi, message);
120 spin_unlock_irq(&spidev->spi_lock);
122 if (status == 0) {
123 wait_for_completion(&done);
124 status = message->status;
125 if (status == 0)
126 status = message->actual_length;
128 return status;
131 static inline ssize_t
132 spidev_sync_write(struct spidev_data *spidev, size_t len)
134 struct spi_transfer t = {
135 .tx_buf = spidev->buffer,
136 .len = len,
138 struct spi_message m;
140 spi_message_init(&m);
141 spi_message_add_tail(&t, &m);
142 return spidev_sync(spidev, &m);
145 static inline ssize_t
146 spidev_sync_read(struct spidev_data *spidev, size_t len)
148 struct spi_transfer t = {
149 .rx_buf = spidev->buffer,
150 .len = len,
152 struct spi_message m;
154 spi_message_init(&m);
155 spi_message_add_tail(&t, &m);
156 return spidev_sync(spidev, &m);
159 /*-------------------------------------------------------------------------*/
161 /* Read-only message with current device setup */
162 static ssize_t
163 spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
165 struct spidev_data *spidev;
166 ssize_t status = 0;
168 /* chipselect only toggles at start or end of operation */
169 if (count > bufsiz)
170 return -EMSGSIZE;
172 spidev = filp->private_data;
174 mutex_lock(&spidev->buf_lock);
175 status = spidev_sync_read(spidev, count);
176 if (status > 0) {
177 unsigned long missing;
179 missing = copy_to_user(buf, spidev->buffer, status);
180 if (missing == status)
181 status = -EFAULT;
182 else
183 status = status - missing;
185 mutex_unlock(&spidev->buf_lock);
187 return status;
190 /* Write-only message with current device setup */
191 static ssize_t
192 spidev_write(struct file *filp, const char __user *buf,
193 size_t count, loff_t *f_pos)
195 struct spidev_data *spidev;
196 ssize_t status = 0;
197 unsigned long missing;
199 /* chipselect only toggles at start or end of operation */
200 if (count > bufsiz)
201 return -EMSGSIZE;
203 spidev = filp->private_data;
205 mutex_lock(&spidev->buf_lock);
206 missing = copy_from_user(spidev->buffer, buf, count);
207 if (missing == 0) {
208 status = spidev_sync_write(spidev, count);
209 } else
210 status = -EFAULT;
211 mutex_unlock(&spidev->buf_lock);
213 return status;
216 static int spidev_message(struct spidev_data *spidev,
217 struct spi_ioc_transfer *u_xfers, unsigned n_xfers)
219 struct spi_message msg;
220 struct spi_transfer *k_xfers;
221 struct spi_transfer *k_tmp;
222 struct spi_ioc_transfer *u_tmp;
223 unsigned n, total;
224 u8 *buf;
225 int status = -EFAULT;
227 spi_message_init(&msg);
228 k_xfers = kcalloc(n_xfers, sizeof(*k_tmp), GFP_KERNEL);
229 if (k_xfers == NULL)
230 return -ENOMEM;
232 /* Construct spi_message, copying any tx data to bounce buffer.
233 * We walk the array of user-provided transfers, using each one
234 * to initialize a kernel version of the same transfer.
236 buf = spidev->buffer;
237 total = 0;
238 for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers;
240 n--, k_tmp++, u_tmp++) {
241 k_tmp->len = u_tmp->len;
243 total += k_tmp->len;
244 if (total > bufsiz) {
245 status = -EMSGSIZE;
246 goto done;
249 if (u_tmp->rx_buf) {
250 k_tmp->rx_buf = buf;
251 if (!access_ok(VERIFY_WRITE, (u8 __user *)
252 (uintptr_t) u_tmp->rx_buf,
253 u_tmp->len))
254 goto done;
256 if (u_tmp->tx_buf) {
257 k_tmp->tx_buf = buf;
258 if (copy_from_user(buf, (const u8 __user *)
259 (uintptr_t) u_tmp->tx_buf,
260 u_tmp->len))
261 goto done;
263 buf += k_tmp->len;
265 k_tmp->cs_change = !!u_tmp->cs_change;
266 k_tmp->bits_per_word = u_tmp->bits_per_word;
267 k_tmp->delay_usecs = u_tmp->delay_usecs;
268 k_tmp->speed_hz = u_tmp->speed_hz;
269 #ifdef VERBOSE
270 dev_dbg(&spidev->spi->dev,
271 " xfer len %zd %s%s%s%dbits %u usec %uHz\n",
272 u_tmp->len,
273 u_tmp->rx_buf ? "rx " : "",
274 u_tmp->tx_buf ? "tx " : "",
275 u_tmp->cs_change ? "cs " : "",
276 u_tmp->bits_per_word ? : spidev->spi->bits_per_word,
277 u_tmp->delay_usecs,
278 u_tmp->speed_hz ? : spidev->spi->max_speed_hz);
279 #endif
280 spi_message_add_tail(k_tmp, &msg);
283 status = spidev_sync(spidev, &msg);
284 if (status < 0)
285 goto done;
287 /* copy any rx data out of bounce buffer */
288 buf = spidev->buffer;
289 for (n = n_xfers, u_tmp = u_xfers; n; n--, u_tmp++) {
290 if (u_tmp->rx_buf) {
291 if (__copy_to_user((u8 __user *)
292 (uintptr_t) u_tmp->rx_buf, buf,
293 u_tmp->len)) {
294 status = -EFAULT;
295 goto done;
298 buf += u_tmp->len;
300 status = total;
302 done:
303 kfree(k_xfers);
304 return status;
307 static long
308 spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
310 int err = 0;
311 int retval = 0;
312 struct spidev_data *spidev;
313 struct spi_device *spi;
314 u32 tmp;
315 unsigned n_ioc;
316 struct spi_ioc_transfer *ioc;
318 /* Check type and command number */
319 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC)
320 return -ENOTTY;
322 /* Check access direction once here; don't repeat below.
323 * IOC_DIR is from the user perspective, while access_ok is
324 * from the kernel perspective; so they look reversed.
326 if (_IOC_DIR(cmd) & _IOC_READ)
327 err = !access_ok(VERIFY_WRITE,
328 (void __user *)arg, _IOC_SIZE(cmd));
329 if (err == 0 && _IOC_DIR(cmd) & _IOC_WRITE)
330 err = !access_ok(VERIFY_READ,
331 (void __user *)arg, _IOC_SIZE(cmd));
332 if (err)
333 return -EFAULT;
335 /* guard against device removal before, or while,
336 * we issue this ioctl.
338 spidev = filp->private_data;
339 spin_lock_irq(&spidev->spi_lock);
340 spi = spi_dev_get(spidev->spi);
341 spin_unlock_irq(&spidev->spi_lock);
343 if (spi == NULL)
344 return -ESHUTDOWN;
346 /* use the buffer lock here for triple duty:
347 * - prevent I/O (from us) so calling spi_setup() is safe;
348 * - prevent concurrent SPI_IOC_WR_* from morphing
349 * data fields while SPI_IOC_RD_* reads them;
350 * - SPI_IOC_MESSAGE needs the buffer locked "normally".
352 mutex_lock(&spidev->buf_lock);
354 switch (cmd) {
355 /* read requests */
356 case SPI_IOC_RD_MODE:
357 retval = __put_user(spi->mode & SPI_MODE_MASK,
358 (__u8 __user *)arg);
359 break;
360 case SPI_IOC_RD_LSB_FIRST:
361 retval = __put_user((spi->mode & SPI_LSB_FIRST) ? 1 : 0,
362 (__u8 __user *)arg);
363 break;
364 case SPI_IOC_RD_BITS_PER_WORD:
365 retval = __put_user(spi->bits_per_word, (__u8 __user *)arg);
366 break;
367 case SPI_IOC_RD_MAX_SPEED_HZ:
368 retval = __put_user(spi->max_speed_hz, (__u32 __user *)arg);
369 break;
371 /* write requests */
372 case SPI_IOC_WR_MODE:
373 retval = __get_user(tmp, (u8 __user *)arg);
374 if (retval == 0) {
375 u8 save = spi->mode;
377 if (tmp & ~SPI_MODE_MASK) {
378 retval = -EINVAL;
379 break;
382 tmp |= spi->mode & ~SPI_MODE_MASK;
383 spi->mode = (u8)tmp;
384 retval = spi_setup(spi);
385 if (retval < 0)
386 spi->mode = save;
387 else
388 dev_dbg(&spi->dev, "spi mode %02x\n", tmp);
390 break;
391 case SPI_IOC_WR_LSB_FIRST:
392 retval = __get_user(tmp, (__u8 __user *)arg);
393 if (retval == 0) {
394 u8 save = spi->mode;
396 if (tmp)
397 spi->mode |= SPI_LSB_FIRST;
398 else
399 spi->mode &= ~SPI_LSB_FIRST;
400 retval = spi_setup(spi);
401 if (retval < 0)
402 spi->mode = save;
403 else
404 dev_dbg(&spi->dev, "%csb first\n",
405 tmp ? 'l' : 'm');
407 break;
408 case SPI_IOC_WR_BITS_PER_WORD:
409 retval = __get_user(tmp, (__u8 __user *)arg);
410 if (retval == 0) {
411 u8 save = spi->bits_per_word;
413 spi->bits_per_word = tmp;
414 retval = spi_setup(spi);
415 if (retval < 0)
416 spi->bits_per_word = save;
417 else
418 dev_dbg(&spi->dev, "%d bits per word\n", tmp);
420 break;
421 case SPI_IOC_WR_MAX_SPEED_HZ:
422 retval = __get_user(tmp, (__u32 __user *)arg);
423 if (retval == 0) {
424 u32 save = spi->max_speed_hz;
426 spi->max_speed_hz = tmp;
427 retval = spi_setup(spi);
428 if (retval < 0)
429 spi->max_speed_hz = save;
430 else
431 dev_dbg(&spi->dev, "%d Hz (max)\n", tmp);
433 break;
435 default:
436 /* segmented and/or full-duplex I/O request */
437 if (_IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0))
438 || _IOC_DIR(cmd) != _IOC_WRITE) {
439 retval = -ENOTTY;
440 break;
443 tmp = _IOC_SIZE(cmd);
444 if ((tmp % sizeof(struct spi_ioc_transfer)) != 0) {
445 retval = -EINVAL;
446 break;
448 n_ioc = tmp / sizeof(struct spi_ioc_transfer);
449 if (n_ioc == 0)
450 break;
452 /* copy into scratch area */
453 ioc = kmalloc(tmp, GFP_KERNEL);
454 if (!ioc) {
455 retval = -ENOMEM;
456 break;
458 if (__copy_from_user(ioc, (void __user *)arg, tmp)) {
459 kfree(ioc);
460 retval = -EFAULT;
461 break;
464 /* translate to spi_message, execute */
465 retval = spidev_message(spidev, ioc, n_ioc);
466 kfree(ioc);
467 break;
470 mutex_unlock(&spidev->buf_lock);
471 spi_dev_put(spi);
472 return retval;
475 #ifdef CONFIG_COMPAT
476 static long
477 spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
479 return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
481 #else
482 #define spidev_compat_ioctl NULL
483 #endif /* CONFIG_COMPAT */
485 static int spidev_open(struct inode *inode, struct file *filp)
487 struct spidev_data *spidev;
488 int status = -ENXIO;
490 mutex_lock(&device_list_lock);
492 list_for_each_entry(spidev, &device_list, device_entry) {
493 if (spidev->devt == inode->i_rdev) {
494 status = 0;
495 break;
498 if (status == 0) {
499 if (!spidev->buffer) {
500 spidev->buffer = kmalloc(bufsiz, GFP_KERNEL);
501 if (!spidev->buffer) {
502 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
503 status = -ENOMEM;
506 if (status == 0) {
507 spidev->users++;
508 filp->private_data = spidev;
509 nonseekable_open(inode, filp);
511 } else
512 pr_debug("spidev: nothing for minor %d\n", iminor(inode));
514 mutex_unlock(&device_list_lock);
515 return status;
518 static int spidev_release(struct inode *inode, struct file *filp)
520 struct spidev_data *spidev;
521 int status = 0;
523 mutex_lock(&device_list_lock);
524 spidev = filp->private_data;
525 filp->private_data = NULL;
527 /* last close? */
528 spidev->users--;
529 if (!spidev->users) {
530 int dofree;
532 kfree(spidev->buffer);
533 spidev->buffer = NULL;
535 /* ... after we unbound from the underlying device? */
536 spin_lock_irq(&spidev->spi_lock);
537 dofree = (spidev->spi == NULL);
538 spin_unlock_irq(&spidev->spi_lock);
540 if (dofree)
541 kfree(spidev);
543 mutex_unlock(&device_list_lock);
545 return status;
548 static const struct file_operations spidev_fops = {
549 .owner = THIS_MODULE,
550 /* REVISIT switch to aio primitives, so that userspace
551 * gets more complete API coverage. It'll simplify things
552 * too, except for the locking.
554 .write = spidev_write,
555 .read = spidev_read,
556 .unlocked_ioctl = spidev_ioctl,
557 .compat_ioctl = spidev_compat_ioctl,
558 .open = spidev_open,
559 .release = spidev_release,
560 .llseek = no_llseek,
563 /*-------------------------------------------------------------------------*/
565 /* The main reason to have this class is to make mdev/udev create the
566 * /dev/spidevB.C character device nodes exposing our userspace API.
567 * It also simplifies memory management.
570 static struct class *spidev_class;
572 /*-------------------------------------------------------------------------*/
574 static int __devinit spidev_probe(struct spi_device *spi)
576 struct spidev_data *spidev;
577 int status;
578 unsigned long minor;
580 /* Allocate driver data */
581 spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);
582 if (!spidev)
583 return -ENOMEM;
585 /* Initialize the driver data */
586 spidev->spi = spi;
587 spin_lock_init(&spidev->spi_lock);
588 mutex_init(&spidev->buf_lock);
590 INIT_LIST_HEAD(&spidev->device_entry);
592 /* If we can allocate a minor number, hook up this device.
593 * Reusing minors is fine so long as udev or mdev is working.
595 mutex_lock(&device_list_lock);
596 minor = find_first_zero_bit(minors, N_SPI_MINORS);
597 if (minor < N_SPI_MINORS) {
598 struct device *dev;
600 spidev->devt = MKDEV(SPIDEV_MAJOR, minor);
601 dev = device_create(spidev_class, &spi->dev, spidev->devt,
602 spidev, "spidev%d.%d",
603 spi->master->bus_num, spi->chip_select);
604 status = IS_ERR(dev) ? PTR_ERR(dev) : 0;
605 } else {
606 dev_dbg(&spi->dev, "no minor number available!\n");
607 status = -ENODEV;
609 if (status == 0) {
610 set_bit(minor, minors);
611 list_add(&spidev->device_entry, &device_list);
613 mutex_unlock(&device_list_lock);
615 if (status == 0)
616 spi_set_drvdata(spi, spidev);
617 else
618 kfree(spidev);
620 return status;
623 static int __devexit spidev_remove(struct spi_device *spi)
625 struct spidev_data *spidev = spi_get_drvdata(spi);
627 /* make sure ops on existing fds can abort cleanly */
628 spin_lock_irq(&spidev->spi_lock);
629 spidev->spi = NULL;
630 spi_set_drvdata(spi, NULL);
631 spin_unlock_irq(&spidev->spi_lock);
633 /* prevent new opens */
634 mutex_lock(&device_list_lock);
635 list_del(&spidev->device_entry);
636 device_destroy(spidev_class, spidev->devt);
637 clear_bit(MINOR(spidev->devt), minors);
638 if (spidev->users == 0)
639 kfree(spidev);
640 mutex_unlock(&device_list_lock);
642 return 0;
645 static struct spi_driver spidev_spi_driver = {
646 .driver = {
647 .name = "spidev",
648 .owner = THIS_MODULE,
650 .probe = spidev_probe,
651 .remove = __devexit_p(spidev_remove),
653 /* NOTE: suspend/resume methods are not necessary here.
654 * We don't do anything except pass the requests to/from
655 * the underlying controller. The refrigerator handles
656 * most issues; the controller driver handles the rest.
660 /*-------------------------------------------------------------------------*/
662 static int __init spidev_init(void)
664 int status;
666 /* Claim our 256 reserved device numbers. Then register a class
667 * that will key udev/mdev to add/remove /dev nodes. Last, register
668 * the driver which manages those device numbers.
670 BUILD_BUG_ON(N_SPI_MINORS > 256);
671 status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);
672 if (status < 0)
673 return status;
675 spidev_class = class_create(THIS_MODULE, "spidev");
676 if (IS_ERR(spidev_class)) {
677 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
678 return PTR_ERR(spidev_class);
681 status = spi_register_driver(&spidev_spi_driver);
682 if (status < 0) {
683 class_destroy(spidev_class);
684 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
686 return status;
688 module_init(spidev_init);
690 static void __exit spidev_exit(void)
692 spi_unregister_driver(&spidev_spi_driver);
693 class_destroy(spidev_class);
694 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
696 module_exit(spidev_exit);
698 MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>");
699 MODULE_DESCRIPTION("User mode SPI device interface");
700 MODULE_LICENSE("GPL");
701 MODULE_ALIAS("spi:spidev");