Version:  2.0.40 2.2.26 2.4.37 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4 4.5

Linux/drivers/spi/spidev.c

  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 
 33 #include <linux/spi/spi.h>
 34 #include <linux/spi/spidev.h>
 35 
 36 #include <linux/uaccess.h>
 37 
 38 
 39 /*
 40  * This supports access 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 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 DECLARE_BITMAP(minors, N_SPI_MINORS);
 56 
 57 
 58 /* Bit masks for spi_device.mode management.  Note that incorrect
 59  * settings for some settings can cause *lots* of trouble for other
 60  * devices on a shared bus:
 61  *
 62  *  - CS_HIGH ... this device will be active when it shouldn't be
 63  *  - 3WIRE ... when active, it won't behave as it should
 64  *  - NO_CS ... there will be no explicit message boundaries; this
 65  *      is completely incompatible with the shared bus model
 66  *  - READY ... transfers may proceed when they shouldn't.
 67  *
 68  * REVISIT should changing those flags be privileged?
 69  */
 70 #define SPI_MODE_MASK           (SPI_CPHA | SPI_CPOL | SPI_CS_HIGH \
 71                                 | SPI_LSB_FIRST | SPI_3WIRE | SPI_LOOP \
 72                                 | SPI_NO_CS | SPI_READY | SPI_TX_DUAL \
 73                                 | SPI_TX_QUAD | SPI_RX_DUAL | SPI_RX_QUAD)
 74 
 75 struct spidev_data {
 76         dev_t                   devt;
 77         spinlock_t              spi_lock;
 78         struct spi_device       *spi;
 79         struct list_head        device_entry;
 80 
 81         /* TX/RX buffers are NULL unless this device is open (users > 0) */
 82         struct mutex            buf_lock;
 83         unsigned                users;
 84         u8                      *tx_buffer;
 85         u8                      *rx_buffer;
 86         u32                     speed_hz;
 87 };
 88 
 89 static LIST_HEAD(device_list);
 90 static DEFINE_MUTEX(device_list_lock);
 91 
 92 static unsigned bufsiz = 4096;
 93 module_param(bufsiz, uint, S_IRUGO);
 94 MODULE_PARM_DESC(bufsiz, "data bytes in biggest supported SPI message");
 95 
 96 /*-------------------------------------------------------------------------*/
 97 
 98 static ssize_t
 99 spidev_sync(struct spidev_data *spidev, struct spi_message *message)
100 {
101         DECLARE_COMPLETION_ONSTACK(done);
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 
120 static inline ssize_t
121 spidev_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 
135 static inline ssize_t
136 spidev_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 */
153 static ssize_t
154 spidev_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 */
182 static ssize_t
183 spidev_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 
207 static 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                         if (!access_ok(VERIFY_WRITE, (u8 __user *)
257                                                 (uintptr_t) u_tmp->rx_buf,
258                                                 u_tmp->len))
259                                 goto done;
260                         rx_buf += k_tmp->len;
261                 }
262                 if (u_tmp->tx_buf) {
263                         /* this transfer needs space in TX bounce buffer */
264                         tx_total += k_tmp->len;
265                         if (tx_total > bufsiz) {
266                                 status = -EMSGSIZE;
267                                 goto done;
268                         }
269                         k_tmp->tx_buf = tx_buf;
270                         if (copy_from_user(tx_buf, (const u8 __user *)
271                                                 (uintptr_t) u_tmp->tx_buf,
272                                         u_tmp->len))
273                                 goto done;
274                         tx_buf += k_tmp->len;
275                 }
276 
277                 k_tmp->cs_change = !!u_tmp->cs_change;
278                 k_tmp->tx_nbits = u_tmp->tx_nbits;
279                 k_tmp->rx_nbits = u_tmp->rx_nbits;
280                 k_tmp->bits_per_word = u_tmp->bits_per_word;
281                 k_tmp->delay_usecs = u_tmp->delay_usecs;
282                 k_tmp->speed_hz = u_tmp->speed_hz;
283                 if (!k_tmp->speed_hz)
284                         k_tmp->speed_hz = spidev->speed_hz;
285 #ifdef VERBOSE
286                 dev_dbg(&spidev->spi->dev,
287                         "  xfer len %u %s%s%s%dbits %u usec %uHz\n",
288                         u_tmp->len,
289                         u_tmp->rx_buf ? "rx " : "",
290                         u_tmp->tx_buf ? "tx " : "",
291                         u_tmp->cs_change ? "cs " : "",
292                         u_tmp->bits_per_word ? : spidev->spi->bits_per_word,
293                         u_tmp->delay_usecs,
294                         u_tmp->speed_hz ? : spidev->spi->max_speed_hz);
295 #endif
296                 spi_message_add_tail(k_tmp, &msg);
297         }
298 
299         status = spidev_sync(spidev, &msg);
300         if (status < 0)
301                 goto done;
302 
303         /* copy any rx data out of bounce buffer */
304         rx_buf = spidev->rx_buffer;
305         for (n = n_xfers, u_tmp = u_xfers; n; n--, u_tmp++) {
306                 if (u_tmp->rx_buf) {
307                         if (__copy_to_user((u8 __user *)
308                                         (uintptr_t) u_tmp->rx_buf, rx_buf,
309                                         u_tmp->len)) {
310                                 status = -EFAULT;
311                                 goto done;
312                         }
313                         rx_buf += u_tmp->len;
314                 }
315         }
316         status = total;
317 
318 done:
319         kfree(k_xfers);
320         return status;
321 }
322 
323 static struct spi_ioc_transfer *
324 spidev_get_ioc_message(unsigned int cmd, struct spi_ioc_transfer __user *u_ioc,
325                 unsigned *n_ioc)
326 {
327         struct spi_ioc_transfer *ioc;
328         u32     tmp;
329 
330         /* Check type, command number and direction */
331         if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC
332                         || _IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0))
333                         || _IOC_DIR(cmd) != _IOC_WRITE)
334                 return ERR_PTR(-ENOTTY);
335 
336         tmp = _IOC_SIZE(cmd);
337         if ((tmp % sizeof(struct spi_ioc_transfer)) != 0)
338                 return ERR_PTR(-EINVAL);
339         *n_ioc = tmp / sizeof(struct spi_ioc_transfer);
340         if (*n_ioc == 0)
341                 return NULL;
342 
343         /* copy into scratch area */
344         ioc = kmalloc(tmp, GFP_KERNEL);
345         if (!ioc)
346                 return ERR_PTR(-ENOMEM);
347         if (__copy_from_user(ioc, u_ioc, tmp)) {
348                 kfree(ioc);
349                 return ERR_PTR(-EFAULT);
350         }
351         return ioc;
352 }
353 
354 static long
355 spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
356 {
357         int                     err = 0;
358         int                     retval = 0;
359         struct spidev_data      *spidev;
360         struct spi_device       *spi;
361         u32                     tmp;
362         unsigned                n_ioc;
363         struct spi_ioc_transfer *ioc;
364 
365         /* Check type and command number */
366         if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC)
367                 return -ENOTTY;
368 
369         /* Check access direction once here; don't repeat below.
370          * IOC_DIR is from the user perspective, while access_ok is
371          * from the kernel perspective; so they look reversed.
372          */
373         if (_IOC_DIR(cmd) & _IOC_READ)
374                 err = !access_ok(VERIFY_WRITE,
375                                 (void __user *)arg, _IOC_SIZE(cmd));
376         if (err == 0 && _IOC_DIR(cmd) & _IOC_WRITE)
377                 err = !access_ok(VERIFY_READ,
378                                 (void __user *)arg, _IOC_SIZE(cmd));
379         if (err)
380                 return -EFAULT;
381 
382         /* guard against device removal before, or while,
383          * we issue this ioctl.
384          */
385         spidev = filp->private_data;
386         spin_lock_irq(&spidev->spi_lock);
387         spi = spi_dev_get(spidev->spi);
388         spin_unlock_irq(&spidev->spi_lock);
389 
390         if (spi == NULL)
391                 return -ESHUTDOWN;
392 
393         /* use the buffer lock here for triple duty:
394          *  - prevent I/O (from us) so calling spi_setup() is safe;
395          *  - prevent concurrent SPI_IOC_WR_* from morphing
396          *    data fields while SPI_IOC_RD_* reads them;
397          *  - SPI_IOC_MESSAGE needs the buffer locked "normally".
398          */
399         mutex_lock(&spidev->buf_lock);
400 
401         switch (cmd) {
402         /* read requests */
403         case SPI_IOC_RD_MODE:
404                 retval = __put_user(spi->mode & SPI_MODE_MASK,
405                                         (__u8 __user *)arg);
406                 break;
407         case SPI_IOC_RD_MODE32:
408                 retval = __put_user(spi->mode & SPI_MODE_MASK,
409                                         (__u32 __user *)arg);
410                 break;
411         case SPI_IOC_RD_LSB_FIRST:
412                 retval = __put_user((spi->mode & SPI_LSB_FIRST) ?  1 : 0,
413                                         (__u8 __user *)arg);
414                 break;
415         case SPI_IOC_RD_BITS_PER_WORD:
416                 retval = __put_user(spi->bits_per_word, (__u8 __user *)arg);
417                 break;
418         case SPI_IOC_RD_MAX_SPEED_HZ:
419                 retval = __put_user(spidev->speed_hz, (__u32 __user *)arg);
420                 break;
421 
422         /* write requests */
423         case SPI_IOC_WR_MODE:
424         case SPI_IOC_WR_MODE32:
425                 if (cmd == SPI_IOC_WR_MODE)
426                         retval = __get_user(tmp, (u8 __user *)arg);
427                 else
428                         retval = __get_user(tmp, (u32 __user *)arg);
429                 if (retval == 0) {
430                         u32     save = spi->mode;
431 
432                         if (tmp & ~SPI_MODE_MASK) {
433                                 retval = -EINVAL;
434                                 break;
435                         }
436 
437                         tmp |= spi->mode & ~SPI_MODE_MASK;
438                         spi->mode = (u16)tmp;
439                         retval = spi_setup(spi);
440                         if (retval < 0)
441                                 spi->mode = save;
442                         else
443                                 dev_dbg(&spi->dev, "spi mode %x\n", tmp);
444                 }
445                 break;
446         case SPI_IOC_WR_LSB_FIRST:
447                 retval = __get_user(tmp, (__u8 __user *)arg);
448                 if (retval == 0) {
449                         u32     save = spi->mode;
450 
451                         if (tmp)
452                                 spi->mode |= SPI_LSB_FIRST;
453                         else
454                                 spi->mode &= ~SPI_LSB_FIRST;
455                         retval = spi_setup(spi);
456                         if (retval < 0)
457                                 spi->mode = save;
458                         else
459                                 dev_dbg(&spi->dev, "%csb first\n",
460                                                 tmp ? 'l' : 'm');
461                 }
462                 break;
463         case SPI_IOC_WR_BITS_PER_WORD:
464                 retval = __get_user(tmp, (__u8 __user *)arg);
465                 if (retval == 0) {
466                         u8      save = spi->bits_per_word;
467 
468                         spi->bits_per_word = tmp;
469                         retval = spi_setup(spi);
470                         if (retval < 0)
471                                 spi->bits_per_word = save;
472                         else
473                                 dev_dbg(&spi->dev, "%d bits per word\n", tmp);
474                 }
475                 break;
476         case SPI_IOC_WR_MAX_SPEED_HZ:
477                 retval = __get_user(tmp, (__u32 __user *)arg);
478                 if (retval == 0) {
479                         u32     save = spi->max_speed_hz;
480 
481                         spi->max_speed_hz = tmp;
482                         retval = spi_setup(spi);
483                         if (retval >= 0)
484                                 spidev->speed_hz = tmp;
485                         else
486                                 dev_dbg(&spi->dev, "%d Hz (max)\n", tmp);
487                         spi->max_speed_hz = save;
488                 }
489                 break;
490 
491         default:
492                 /* segmented and/or full-duplex I/O request */
493                 /* Check message and copy into scratch area */
494                 ioc = spidev_get_ioc_message(cmd,
495                                 (struct spi_ioc_transfer __user *)arg, &n_ioc);
496                 if (IS_ERR(ioc)) {
497                         retval = PTR_ERR(ioc);
498                         break;
499                 }
500                 if (!ioc)
501                         break;  /* n_ioc is also 0 */
502 
503                 /* translate to spi_message, execute */
504                 retval = spidev_message(spidev, ioc, n_ioc);
505                 kfree(ioc);
506                 break;
507         }
508 
509         mutex_unlock(&spidev->buf_lock);
510         spi_dev_put(spi);
511         return retval;
512 }
513 
514 #ifdef CONFIG_COMPAT
515 static long
516 spidev_compat_ioc_message(struct file *filp, unsigned int cmd,
517                 unsigned long arg)
518 {
519         struct spi_ioc_transfer __user  *u_ioc;
520         int                             retval = 0;
521         struct spidev_data              *spidev;
522         struct spi_device               *spi;
523         unsigned                        n_ioc, n;
524         struct spi_ioc_transfer         *ioc;
525 
526         u_ioc = (struct spi_ioc_transfer __user *) compat_ptr(arg);
527         if (!access_ok(VERIFY_READ, u_ioc, _IOC_SIZE(cmd)))
528                 return -EFAULT;
529 
530         /* guard against device removal before, or while,
531          * we issue this ioctl.
532          */
533         spidev = filp->private_data;
534         spin_lock_irq(&spidev->spi_lock);
535         spi = spi_dev_get(spidev->spi);
536         spin_unlock_irq(&spidev->spi_lock);
537 
538         if (spi == NULL)
539                 return -ESHUTDOWN;
540 
541         /* SPI_IOC_MESSAGE needs the buffer locked "normally" */
542         mutex_lock(&spidev->buf_lock);
543 
544         /* Check message and copy into scratch area */
545         ioc = spidev_get_ioc_message(cmd, u_ioc, &n_ioc);
546         if (IS_ERR(ioc)) {
547                 retval = PTR_ERR(ioc);
548                 goto done;
549         }
550         if (!ioc)
551                 goto done;      /* n_ioc is also 0 */
552 
553         /* Convert buffer pointers */
554         for (n = 0; n < n_ioc; n++) {
555                 ioc[n].rx_buf = (uintptr_t) compat_ptr(ioc[n].rx_buf);
556                 ioc[n].tx_buf = (uintptr_t) compat_ptr(ioc[n].tx_buf);
557         }
558 
559         /* translate to spi_message, execute */
560         retval = spidev_message(spidev, ioc, n_ioc);
561         kfree(ioc);
562 
563 done:
564         mutex_unlock(&spidev->buf_lock);
565         spi_dev_put(spi);
566         return retval;
567 }
568 
569 static long
570 spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
571 {
572         if (_IOC_TYPE(cmd) == SPI_IOC_MAGIC
573                         && _IOC_NR(cmd) == _IOC_NR(SPI_IOC_MESSAGE(0))
574                         && _IOC_DIR(cmd) == _IOC_WRITE)
575                 return spidev_compat_ioc_message(filp, cmd, arg);
576 
577         return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
578 }
579 #else
580 #define spidev_compat_ioctl NULL
581 #endif /* CONFIG_COMPAT */
582 
583 static int spidev_open(struct inode *inode, struct file *filp)
584 {
585         struct spidev_data      *spidev;
586         int                     status = -ENXIO;
587 
588         mutex_lock(&device_list_lock);
589 
590         list_for_each_entry(spidev, &device_list, device_entry) {
591                 if (spidev->devt == inode->i_rdev) {
592                         status = 0;
593                         break;
594                 }
595         }
596 
597         if (status) {
598                 pr_debug("spidev: nothing for minor %d\n", iminor(inode));
599                 goto err_find_dev;
600         }
601 
602         if (!spidev->tx_buffer) {
603                 spidev->tx_buffer = kmalloc(bufsiz, GFP_KERNEL);
604                 if (!spidev->tx_buffer) {
605                         dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
606                         status = -ENOMEM;
607                         goto err_find_dev;
608                 }
609         }
610 
611         if (!spidev->rx_buffer) {
612                 spidev->rx_buffer = kmalloc(bufsiz, GFP_KERNEL);
613                 if (!spidev->rx_buffer) {
614                         dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
615                         status = -ENOMEM;
616                         goto err_alloc_rx_buf;
617                 }
618         }
619 
620         spidev->users++;
621         filp->private_data = spidev;
622         nonseekable_open(inode, filp);
623 
624         mutex_unlock(&device_list_lock);
625         return 0;
626 
627 err_alloc_rx_buf:
628         kfree(spidev->tx_buffer);
629         spidev->tx_buffer = NULL;
630 err_find_dev:
631         mutex_unlock(&device_list_lock);
632         return status;
633 }
634 
635 static int spidev_release(struct inode *inode, struct file *filp)
636 {
637         struct spidev_data      *spidev;
638 
639         mutex_lock(&device_list_lock);
640         spidev = filp->private_data;
641         filp->private_data = NULL;
642 
643         /* last close? */
644         spidev->users--;
645         if (!spidev->users) {
646                 int             dofree;
647 
648                 kfree(spidev->tx_buffer);
649                 spidev->tx_buffer = NULL;
650 
651                 kfree(spidev->rx_buffer);
652                 spidev->rx_buffer = NULL;
653 
654                 spin_lock_irq(&spidev->spi_lock);
655                 if (spidev->spi)
656                         spidev->speed_hz = spidev->spi->max_speed_hz;
657 
658                 /* ... after we unbound from the underlying device? */
659                 dofree = (spidev->spi == NULL);
660                 spin_unlock_irq(&spidev->spi_lock);
661 
662                 if (dofree)
663                         kfree(spidev);
664         }
665         mutex_unlock(&device_list_lock);
666 
667         return 0;
668 }
669 
670 static const struct file_operations spidev_fops = {
671         .owner =        THIS_MODULE,
672         /* REVISIT switch to aio primitives, so that userspace
673          * gets more complete API coverage.  It'll simplify things
674          * too, except for the locking.
675          */
676         .write =        spidev_write,
677         .read =         spidev_read,
678         .unlocked_ioctl = spidev_ioctl,
679         .compat_ioctl = spidev_compat_ioctl,
680         .open =         spidev_open,
681         .release =      spidev_release,
682         .llseek =       no_llseek,
683 };
684 
685 /*-------------------------------------------------------------------------*/
686 
687 /* The main reason to have this class is to make mdev/udev create the
688  * /dev/spidevB.C character device nodes exposing our userspace API.
689  * It also simplifies memory management.
690  */
691 
692 static struct class *spidev_class;
693 
694 #ifdef CONFIG_OF
695 static const struct of_device_id spidev_dt_ids[] = {
696         { .compatible = "rohm,dh2228fv" },
697         { .compatible = "lineartechnology,ltc2488" },
698         {},
699 };
700 MODULE_DEVICE_TABLE(of, spidev_dt_ids);
701 #endif
702 
703 /*-------------------------------------------------------------------------*/
704 
705 static int spidev_probe(struct spi_device *spi)
706 {
707         struct spidev_data      *spidev;
708         int                     status;
709         unsigned long           minor;
710 
711         /*
712          * spidev should never be referenced in DT without a specific
713          * compatible string, it is a Linux implementation thing
714          * rather than a description of the hardware.
715          */
716         if (spi->dev.of_node && !of_match_device(spidev_dt_ids, &spi->dev)) {
717                 dev_err(&spi->dev, "buggy DT: spidev listed directly in DT\n");
718                 WARN_ON(spi->dev.of_node &&
719                         !of_match_device(spidev_dt_ids, &spi->dev));
720         }
721 
722         /* Allocate driver data */
723         spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);
724         if (!spidev)
725                 return -ENOMEM;
726 
727         /* Initialize the driver data */
728         spidev->spi = spi;
729         spin_lock_init(&spidev->spi_lock);
730         mutex_init(&spidev->buf_lock);
731 
732         INIT_LIST_HEAD(&spidev->device_entry);
733 
734         /* If we can allocate a minor number, hook up this device.
735          * Reusing minors is fine so long as udev or mdev is working.
736          */
737         mutex_lock(&device_list_lock);
738         minor = find_first_zero_bit(minors, N_SPI_MINORS);
739         if (minor < N_SPI_MINORS) {
740                 struct device *dev;
741 
742                 spidev->devt = MKDEV(SPIDEV_MAJOR, minor);
743                 dev = device_create(spidev_class, &spi->dev, spidev->devt,
744                                     spidev, "spidev%d.%d",
745                                     spi->master->bus_num, spi->chip_select);
746                 status = PTR_ERR_OR_ZERO(dev);
747         } else {
748                 dev_dbg(&spi->dev, "no minor number available!\n");
749                 status = -ENODEV;
750         }
751         if (status == 0) {
752                 set_bit(minor, minors);
753                 list_add(&spidev->device_entry, &device_list);
754         }
755         mutex_unlock(&device_list_lock);
756 
757         spidev->speed_hz = spi->max_speed_hz;
758 
759         if (status == 0)
760                 spi_set_drvdata(spi, spidev);
761         else
762                 kfree(spidev);
763 
764         return status;
765 }
766 
767 static int spidev_remove(struct spi_device *spi)
768 {
769         struct spidev_data      *spidev = spi_get_drvdata(spi);
770 
771         /* make sure ops on existing fds can abort cleanly */
772         spin_lock_irq(&spidev->spi_lock);
773         spidev->spi = NULL;
774         spin_unlock_irq(&spidev->spi_lock);
775 
776         /* prevent new opens */
777         mutex_lock(&device_list_lock);
778         list_del(&spidev->device_entry);
779         device_destroy(spidev_class, spidev->devt);
780         clear_bit(MINOR(spidev->devt), minors);
781         if (spidev->users == 0)
782                 kfree(spidev);
783         mutex_unlock(&device_list_lock);
784 
785         return 0;
786 }
787 
788 static struct spi_driver spidev_spi_driver = {
789         .driver = {
790                 .name =         "spidev",
791                 .of_match_table = of_match_ptr(spidev_dt_ids),
792         },
793         .probe =        spidev_probe,
794         .remove =       spidev_remove,
795 
796         /* NOTE:  suspend/resume methods are not necessary here.
797          * We don't do anything except pass the requests to/from
798          * the underlying controller.  The refrigerator handles
799          * most issues; the controller driver handles the rest.
800          */
801 };
802 
803 /*-------------------------------------------------------------------------*/
804 
805 static int __init spidev_init(void)
806 {
807         int status;
808 
809         /* Claim our 256 reserved device numbers.  Then register a class
810          * that will key udev/mdev to add/remove /dev nodes.  Last, register
811          * the driver which manages those device numbers.
812          */
813         BUILD_BUG_ON(N_SPI_MINORS > 256);
814         status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);
815         if (status < 0)
816                 return status;
817 
818         spidev_class = class_create(THIS_MODULE, "spidev");
819         if (IS_ERR(spidev_class)) {
820                 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
821                 return PTR_ERR(spidev_class);
822         }
823 
824         status = spi_register_driver(&spidev_spi_driver);
825         if (status < 0) {
826                 class_destroy(spidev_class);
827                 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
828         }
829         return status;
830 }
831 module_init(spidev_init);
832 
833 static void __exit spidev_exit(void)
834 {
835         spi_unregister_driver(&spidev_spi_driver);
836         class_destroy(spidev_class);
837         unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
838 }
839 module_exit(spidev_exit);
840 
841 MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>");
842 MODULE_DESCRIPTION("User mode SPI device interface");
843 MODULE_LICENSE("GPL");
844 MODULE_ALIAS("spi:spidev");
845 

This page was automatically generated by LXR 0.3.1 (source).  •  Linux is a registered trademark of Linus Torvalds  •  Contact us