spidev compiler warning gone
[linux-2.6] / drivers / spi / spidev.c
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
171                 total += k_tmp->len;
172                 if (total > bufsiz) {
173                         status = -EMSGSIZE;
174                         goto done;
175                 }
176
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;
184                         if (copy_from_user(buf, (const u8 __user *)
185                                                 (ptrdiff_t) u_tmp->tx_buf,
186                                         u_tmp->len))
187                                 goto done;
188                 }
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) {
217                         if (__copy_to_user((u8 __user *)
218                                         (ptrdiff_t) u_tmp->rx_buf, buf,
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)) {
369                         kfree(ioc);
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);
490         minor = find_first_zero_bit(minors, N_SPI_MINORS);
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");