Version:  2.0.40 2.2.26 2.4.37 3.4 3.5 3.6 3.7 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

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 /*
 99  * We can't use the standard synchronous wrappers for file I/O; we
100  * need to protect against async removal of the underlying spi_device.
101  */
102 static void spidev_complete(void *arg)
103 {
104         complete(arg);
105 }
106 
107 static ssize_t
108 spidev_sync(struct spidev_data *spidev, struct spi_message *message)
109 {
110         DECLARE_COMPLETION_ONSTACK(done);
111         int status;
112 
113         message->complete = spidev_complete;
114         message->context = &done;
115 
116         spin_lock_irq(&spidev->spi_lock);
117         if (spidev->spi == NULL)
118                 status = -ESHUTDOWN;
119         else
120                 status = spi_async(spidev->spi, message);
121         spin_unlock_irq(&spidev->spi_lock);
122 
123         if (status == 0) {
124                 wait_for_completion(&done);
125                 status = message->status;
126                 if (status == 0)
127                         status = message->actual_length;
128         }
129         return status;
130 }
131 
132 static inline ssize_t
133 spidev_sync_write(struct spidev_data *spidev, size_t len)
134 {
135         struct spi_transfer     t = {
136                         .tx_buf         = spidev->tx_buffer,
137                         .len            = len,
138                         .speed_hz       = spidev->speed_hz,
139                 };
140         struct spi_message      m;
141 
142         spi_message_init(&m);
143         spi_message_add_tail(&t, &m);
144         return spidev_sync(spidev, &m);
145 }
146 
147 static inline ssize_t
148 spidev_sync_read(struct spidev_data *spidev, size_t len)
149 {
150         struct spi_transfer     t = {
151                         .rx_buf         = spidev->rx_buffer,
152                         .len            = len,
153                         .speed_hz       = spidev->speed_hz,
154                 };
155         struct spi_message      m;
156 
157         spi_message_init(&m);
158         spi_message_add_tail(&t, &m);
159         return spidev_sync(spidev, &m);
160 }
161 
162 /*-------------------------------------------------------------------------*/
163 
164 /* Read-only message with current device setup */
165 static ssize_t
166 spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
167 {
168         struct spidev_data      *spidev;
169         ssize_t                 status = 0;
170 
171         /* chipselect only toggles at start or end of operation */
172         if (count > bufsiz)
173                 return -EMSGSIZE;
174 
175         spidev = filp->private_data;
176 
177         mutex_lock(&spidev->buf_lock);
178         status = spidev_sync_read(spidev, count);
179         if (status > 0) {
180                 unsigned long   missing;
181 
182                 missing = copy_to_user(buf, spidev->rx_buffer, status);
183                 if (missing == status)
184                         status = -EFAULT;
185                 else
186                         status = status - missing;
187         }
188         mutex_unlock(&spidev->buf_lock);
189 
190         return status;
191 }
192 
193 /* Write-only message with current device setup */
194 static ssize_t
195 spidev_write(struct file *filp, const char __user *buf,
196                 size_t count, loff_t *f_pos)
197 {
198         struct spidev_data      *spidev;
199         ssize_t                 status = 0;
200         unsigned long           missing;
201 
202         /* chipselect only toggles at start or end of operation */
203         if (count > bufsiz)
204                 return -EMSGSIZE;
205 
206         spidev = filp->private_data;
207 
208         mutex_lock(&spidev->buf_lock);
209         missing = copy_from_user(spidev->tx_buffer, buf, count);
210         if (missing == 0)
211                 status = spidev_sync_write(spidev, count);
212         else
213                 status = -EFAULT;
214         mutex_unlock(&spidev->buf_lock);
215 
216         return status;
217 }
218 
219 static int spidev_message(struct spidev_data *spidev,
220                 struct spi_ioc_transfer *u_xfers, unsigned n_xfers)
221 {
222         struct spi_message      msg;
223         struct spi_transfer     *k_xfers;
224         struct spi_transfer     *k_tmp;
225         struct spi_ioc_transfer *u_tmp;
226         unsigned                n, total;
227         u8                      *tx_buf, *rx_buf;
228         int                     status = -EFAULT;
229 
230         spi_message_init(&msg);
231         k_xfers = kcalloc(n_xfers, sizeof(*k_tmp), GFP_KERNEL);
232         if (k_xfers == NULL)
233                 return -ENOMEM;
234 
235         /* Construct spi_message, copying any tx data to bounce buffer.
236          * We walk the array of user-provided transfers, using each one
237          * to initialize a kernel version of the same transfer.
238          */
239         tx_buf = spidev->tx_buffer;
240         rx_buf = spidev->rx_buffer;
241         total = 0;
242         for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers;
243                         n;
244                         n--, k_tmp++, u_tmp++) {
245                 k_tmp->len = u_tmp->len;
246 
247                 total += k_tmp->len;
248                 if (total > bufsiz) {
249                         status = -EMSGSIZE;
250                         goto done;
251                 }
252 
253                 if (u_tmp->rx_buf) {
254                         k_tmp->rx_buf = rx_buf;
255                         if (!access_ok(VERIFY_WRITE, (u8 __user *)
256                                                 (uintptr_t) u_tmp->rx_buf,
257                                                 u_tmp->len))
258                                 goto done;
259                 }
260                 if (u_tmp->tx_buf) {
261                         k_tmp->tx_buf = tx_buf;
262                         if (copy_from_user(tx_buf, (const u8 __user *)
263                                                 (uintptr_t) u_tmp->tx_buf,
264                                         u_tmp->len))
265                                 goto done;
266                 }
267                 tx_buf += k_tmp->len;
268                 rx_buf += k_tmp->len;
269 
270                 k_tmp->cs_change = !!u_tmp->cs_change;
271                 k_tmp->tx_nbits = u_tmp->tx_nbits;
272                 k_tmp->rx_nbits = u_tmp->rx_nbits;
273                 k_tmp->bits_per_word = u_tmp->bits_per_word;
274                 k_tmp->delay_usecs = u_tmp->delay_usecs;
275                 k_tmp->speed_hz = u_tmp->speed_hz;
276                 if (!k_tmp->speed_hz)
277                         k_tmp->speed_hz = spidev->speed_hz;
278 #ifdef VERBOSE
279                 dev_dbg(&spidev->spi->dev,
280                         "  xfer len %zd %s%s%s%dbits %u usec %uHz\n",
281                         u_tmp->len,
282                         u_tmp->rx_buf ? "rx " : "",
283                         u_tmp->tx_buf ? "tx " : "",
284                         u_tmp->cs_change ? "cs " : "",
285                         u_tmp->bits_per_word ? : spidev->spi->bits_per_word,
286                         u_tmp->delay_usecs,
287                         u_tmp->speed_hz ? : spidev->spi->max_speed_hz);
288 #endif
289                 spi_message_add_tail(k_tmp, &msg);
290         }
291 
292         status = spidev_sync(spidev, &msg);
293         if (status < 0)
294                 goto done;
295 
296         /* copy any rx data out of bounce buffer */
297         rx_buf = spidev->rx_buffer;
298         for (n = n_xfers, u_tmp = u_xfers; n; n--, u_tmp++) {
299                 if (u_tmp->rx_buf) {
300                         if (__copy_to_user((u8 __user *)
301                                         (uintptr_t) u_tmp->rx_buf, rx_buf,
302                                         u_tmp->len)) {
303                                 status = -EFAULT;
304                                 goto done;
305                         }
306                 }
307                 rx_buf += u_tmp->len;
308         }
309         status = total;
310 
311 done:
312         kfree(k_xfers);
313         return status;
314 }
315 
316 static struct spi_ioc_transfer *
317 spidev_get_ioc_message(unsigned int cmd, struct spi_ioc_transfer __user *u_ioc,
318                 unsigned *n_ioc)
319 {
320         struct spi_ioc_transfer *ioc;
321         u32     tmp;
322 
323         /* Check type, command number and direction */
324         if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC
325                         || _IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0))
326                         || _IOC_DIR(cmd) != _IOC_WRITE)
327                 return ERR_PTR(-ENOTTY);
328 
329         tmp = _IOC_SIZE(cmd);
330         if ((tmp % sizeof(struct spi_ioc_transfer)) != 0)
331                 return ERR_PTR(-EINVAL);
332         *n_ioc = tmp / sizeof(struct spi_ioc_transfer);
333         if (*n_ioc == 0)
334                 return NULL;
335 
336         /* copy into scratch area */
337         ioc = kmalloc(tmp, GFP_KERNEL);
338         if (!ioc)
339                 return ERR_PTR(-ENOMEM);
340         if (__copy_from_user(ioc, u_ioc, tmp)) {
341                 kfree(ioc);
342                 return ERR_PTR(-EFAULT);
343         }
344         return ioc;
345 }
346 
347 static long
348 spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
349 {
350         int                     err = 0;
351         int                     retval = 0;
352         struct spidev_data      *spidev;
353         struct spi_device       *spi;
354         u32                     tmp;
355         unsigned                n_ioc;
356         struct spi_ioc_transfer *ioc;
357 
358         /* Check type and command number */
359         if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC)
360                 return -ENOTTY;
361 
362         /* Check access direction once here; don't repeat below.
363          * IOC_DIR is from the user perspective, while access_ok is
364          * from the kernel perspective; so they look reversed.
365          */
366         if (_IOC_DIR(cmd) & _IOC_READ)
367                 err = !access_ok(VERIFY_WRITE,
368                                 (void __user *)arg, _IOC_SIZE(cmd));
369         if (err == 0 && _IOC_DIR(cmd) & _IOC_WRITE)
370                 err = !access_ok(VERIFY_READ,
371                                 (void __user *)arg, _IOC_SIZE(cmd));
372         if (err)
373                 return -EFAULT;
374 
375         /* guard against device removal before, or while,
376          * we issue this ioctl.
377          */
378         spidev = filp->private_data;
379         spin_lock_irq(&spidev->spi_lock);
380         spi = spi_dev_get(spidev->spi);
381         spin_unlock_irq(&spidev->spi_lock);
382 
383         if (spi == NULL)
384                 return -ESHUTDOWN;
385 
386         /* use the buffer lock here for triple duty:
387          *  - prevent I/O (from us) so calling spi_setup() is safe;
388          *  - prevent concurrent SPI_IOC_WR_* from morphing
389          *    data fields while SPI_IOC_RD_* reads them;
390          *  - SPI_IOC_MESSAGE needs the buffer locked "normally".
391          */
392         mutex_lock(&spidev->buf_lock);
393 
394         switch (cmd) {
395         /* read requests */
396         case SPI_IOC_RD_MODE:
397                 retval = __put_user(spi->mode & SPI_MODE_MASK,
398                                         (__u8 __user *)arg);
399                 break;
400         case SPI_IOC_RD_MODE32:
401                 retval = __put_user(spi->mode & SPI_MODE_MASK,
402                                         (__u32 __user *)arg);
403                 break;
404         case SPI_IOC_RD_LSB_FIRST:
405                 retval = __put_user((spi->mode & SPI_LSB_FIRST) ?  1 : 0,
406                                         (__u8 __user *)arg);
407                 break;
408         case SPI_IOC_RD_BITS_PER_WORD:
409                 retval = __put_user(spi->bits_per_word, (__u8 __user *)arg);
410                 break;
411         case SPI_IOC_RD_MAX_SPEED_HZ:
412                 retval = __put_user(spidev->speed_hz, (__u32 __user *)arg);
413                 break;
414 
415         /* write requests */
416         case SPI_IOC_WR_MODE:
417         case SPI_IOC_WR_MODE32:
418                 if (cmd == SPI_IOC_WR_MODE)
419                         retval = __get_user(tmp, (u8 __user *)arg);
420                 else
421                         retval = __get_user(tmp, (u32 __user *)arg);
422                 if (retval == 0) {
423                         u32     save = spi->mode;
424 
425                         if (tmp & ~SPI_MODE_MASK) {
426                                 retval = -EINVAL;
427                                 break;
428                         }
429 
430                         tmp |= spi->mode & ~SPI_MODE_MASK;
431                         spi->mode = (u16)tmp;
432                         retval = spi_setup(spi);
433                         if (retval < 0)
434                                 spi->mode = save;
435                         else
436                                 dev_dbg(&spi->dev, "spi mode %x\n", tmp);
437                 }
438                 break;
439         case SPI_IOC_WR_LSB_FIRST:
440                 retval = __get_user(tmp, (__u8 __user *)arg);
441                 if (retval == 0) {
442                         u32     save = spi->mode;
443 
444                         if (tmp)
445                                 spi->mode |= SPI_LSB_FIRST;
446                         else
447                                 spi->mode &= ~SPI_LSB_FIRST;
448                         retval = spi_setup(spi);
449                         if (retval < 0)
450                                 spi->mode = save;
451                         else
452                                 dev_dbg(&spi->dev, "%csb first\n",
453                                                 tmp ? 'l' : 'm');
454                 }
455                 break;
456         case SPI_IOC_WR_BITS_PER_WORD:
457                 retval = __get_user(tmp, (__u8 __user *)arg);
458                 if (retval == 0) {
459                         u8      save = spi->bits_per_word;
460 
461                         spi->bits_per_word = tmp;
462                         retval = spi_setup(spi);
463                         if (retval < 0)
464                                 spi->bits_per_word = save;
465                         else
466                                 dev_dbg(&spi->dev, "%d bits per word\n", tmp);
467                 }
468                 break;
469         case SPI_IOC_WR_MAX_SPEED_HZ:
470                 retval = __get_user(tmp, (__u32 __user *)arg);
471                 if (retval == 0) {
472                         u32     save = spi->max_speed_hz;
473 
474                         spi->max_speed_hz = tmp;
475                         retval = spi_setup(spi);
476                         if (retval >= 0)
477                                 spidev->speed_hz = tmp;
478                         else
479                                 dev_dbg(&spi->dev, "%d Hz (max)\n", tmp);
480                         spi->max_speed_hz = save;
481                 }
482                 break;
483 
484         default:
485                 /* segmented and/or full-duplex I/O request */
486                 /* Check message and copy into scratch area */
487                 ioc = spidev_get_ioc_message(cmd,
488                                 (struct spi_ioc_transfer __user *)arg, &n_ioc);
489                 if (IS_ERR(ioc)) {
490                         retval = PTR_ERR(ioc);
491                         break;
492                 }
493                 if (!ioc)
494                         break;  /* n_ioc is also 0 */
495 
496                 /* translate to spi_message, execute */
497                 retval = spidev_message(spidev, ioc, n_ioc);
498                 kfree(ioc);
499                 break;
500         }
501 
502         mutex_unlock(&spidev->buf_lock);
503         spi_dev_put(spi);
504         return retval;
505 }
506 
507 #ifdef CONFIG_COMPAT
508 static long
509 spidev_compat_ioc_message(struct file *filp, unsigned int cmd,
510                 unsigned long arg)
511 {
512         struct spi_ioc_transfer __user  *u_ioc;
513         int                             retval = 0;
514         struct spidev_data              *spidev;
515         struct spi_device               *spi;
516         unsigned                        n_ioc, n;
517         struct spi_ioc_transfer         *ioc;
518 
519         u_ioc = (struct spi_ioc_transfer __user *) compat_ptr(arg);
520         if (!access_ok(VERIFY_READ, u_ioc, _IOC_SIZE(cmd)))
521                 return -EFAULT;
522 
523         /* guard against device removal before, or while,
524          * we issue this ioctl.
525          */
526         spidev = filp->private_data;
527         spin_lock_irq(&spidev->spi_lock);
528         spi = spi_dev_get(spidev->spi);
529         spin_unlock_irq(&spidev->spi_lock);
530 
531         if (spi == NULL)
532                 return -ESHUTDOWN;
533 
534         /* SPI_IOC_MESSAGE needs the buffer locked "normally" */
535         mutex_lock(&spidev->buf_lock);
536 
537         /* Check message and copy into scratch area */
538         ioc = spidev_get_ioc_message(cmd, u_ioc, &n_ioc);
539         if (IS_ERR(ioc)) {
540                 retval = PTR_ERR(ioc);
541                 goto done;
542         }
543         if (!ioc)
544                 goto done;      /* n_ioc is also 0 */
545 
546         /* Convert buffer pointers */
547         for (n = 0; n < n_ioc; n++) {
548                 ioc[n].rx_buf = (uintptr_t) compat_ptr(ioc[n].rx_buf);
549                 ioc[n].tx_buf = (uintptr_t) compat_ptr(ioc[n].tx_buf);
550         }
551 
552         /* translate to spi_message, execute */
553         retval = spidev_message(spidev, ioc, n_ioc);
554         kfree(ioc);
555 
556 done:
557         mutex_unlock(&spidev->buf_lock);
558         spi_dev_put(spi);
559         return retval;
560 }
561 
562 static long
563 spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
564 {
565         if (_IOC_TYPE(cmd) == SPI_IOC_MAGIC
566                         && _IOC_NR(cmd) == _IOC_NR(SPI_IOC_MESSAGE(0))
567                         && _IOC_DIR(cmd) == _IOC_WRITE)
568                 return spidev_compat_ioc_message(filp, cmd, arg);
569 
570         return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
571 }
572 #else
573 #define spidev_compat_ioctl NULL
574 #endif /* CONFIG_COMPAT */
575 
576 static int spidev_open(struct inode *inode, struct file *filp)
577 {
578         struct spidev_data      *spidev;
579         int                     status = -ENXIO;
580 
581         mutex_lock(&device_list_lock);
582 
583         list_for_each_entry(spidev, &device_list, device_entry) {
584                 if (spidev->devt == inode->i_rdev) {
585                         status = 0;
586                         break;
587                 }
588         }
589 
590         if (status) {
591                 pr_debug("spidev: nothing for minor %d\n", iminor(inode));
592                 goto err_find_dev;
593         }
594 
595         if (!spidev->tx_buffer) {
596                 spidev->tx_buffer = kmalloc(bufsiz, GFP_KERNEL);
597                 if (!spidev->tx_buffer) {
598                                 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
599                                 status = -ENOMEM;
600                         goto err_find_dev;
601                         }
602                 }
603 
604         if (!spidev->rx_buffer) {
605                 spidev->rx_buffer = kmalloc(bufsiz, GFP_KERNEL);
606                 if (!spidev->rx_buffer) {
607                         dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
608                         status = -ENOMEM;
609                         goto err_alloc_rx_buf;
610                 }
611         }
612 
613         spidev->users++;
614         filp->private_data = spidev;
615         nonseekable_open(inode, filp);
616 
617         mutex_unlock(&device_list_lock);
618         return 0;
619 
620 err_alloc_rx_buf:
621         kfree(spidev->tx_buffer);
622         spidev->tx_buffer = NULL;
623 err_find_dev:
624         mutex_unlock(&device_list_lock);
625         return status;
626 }
627 
628 static int spidev_release(struct inode *inode, struct file *filp)
629 {
630         struct spidev_data      *spidev;
631         int                     status = 0;
632 
633         mutex_lock(&device_list_lock);
634         spidev = filp->private_data;
635         filp->private_data = NULL;
636 
637         /* last close? */
638         spidev->users--;
639         if (!spidev->users) {
640                 int             dofree;
641 
642                 kfree(spidev->tx_buffer);
643                 spidev->tx_buffer = NULL;
644 
645                 kfree(spidev->rx_buffer);
646                 spidev->rx_buffer = NULL;
647 
648                 spidev->speed_hz = spidev->spi->max_speed_hz;
649 
650                 /* ... after we unbound from the underlying device? */
651                 spin_lock_irq(&spidev->spi_lock);
652                 dofree = (spidev->spi == NULL);
653                 spin_unlock_irq(&spidev->spi_lock);
654 
655                 if (dofree)
656                         kfree(spidev);
657         }
658         mutex_unlock(&device_list_lock);
659 
660         return status;
661 }
662 
663 static const struct file_operations spidev_fops = {
664         .owner =        THIS_MODULE,
665         /* REVISIT switch to aio primitives, so that userspace
666          * gets more complete API coverage.  It'll simplify things
667          * too, except for the locking.
668          */
669         .write =        spidev_write,
670         .read =         spidev_read,
671         .unlocked_ioctl = spidev_ioctl,
672         .compat_ioctl = spidev_compat_ioctl,
673         .open =         spidev_open,
674         .release =      spidev_release,
675         .llseek =       no_llseek,
676 };
677 
678 /*-------------------------------------------------------------------------*/
679 
680 /* The main reason to have this class is to make mdev/udev create the
681  * /dev/spidevB.C character device nodes exposing our userspace API.
682  * It also simplifies memory management.
683  */
684 
685 static struct class *spidev_class;
686 
687 /*-------------------------------------------------------------------------*/
688 
689 static int spidev_probe(struct spi_device *spi)
690 {
691         struct spidev_data      *spidev;
692         int                     status;
693         unsigned long           minor;
694 
695         /* Allocate driver data */
696         spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);
697         if (!spidev)
698                 return -ENOMEM;
699 
700         /* Initialize the driver data */
701         spidev->spi = spi;
702         spin_lock_init(&spidev->spi_lock);
703         mutex_init(&spidev->buf_lock);
704 
705         INIT_LIST_HEAD(&spidev->device_entry);
706 
707         /* If we can allocate a minor number, hook up this device.
708          * Reusing minors is fine so long as udev or mdev is working.
709          */
710         mutex_lock(&device_list_lock);
711         minor = find_first_zero_bit(minors, N_SPI_MINORS);
712         if (minor < N_SPI_MINORS) {
713                 struct device *dev;
714 
715                 spidev->devt = MKDEV(SPIDEV_MAJOR, minor);
716                 dev = device_create(spidev_class, &spi->dev, spidev->devt,
717                                     spidev, "spidev%d.%d",
718                                     spi->master->bus_num, spi->chip_select);
719                 status = PTR_ERR_OR_ZERO(dev);
720         } else {
721                 dev_dbg(&spi->dev, "no minor number available!\n");
722                 status = -ENODEV;
723         }
724         if (status == 0) {
725                 set_bit(minor, minors);
726                 list_add(&spidev->device_entry, &device_list);
727         }
728         mutex_unlock(&device_list_lock);
729 
730         spidev->speed_hz = spi->max_speed_hz;
731 
732         if (status == 0)
733                 spi_set_drvdata(spi, spidev);
734         else
735                 kfree(spidev);
736 
737         return status;
738 }
739 
740 static int spidev_remove(struct spi_device *spi)
741 {
742         struct spidev_data      *spidev = spi_get_drvdata(spi);
743 
744         /* make sure ops on existing fds can abort cleanly */
745         spin_lock_irq(&spidev->spi_lock);
746         spidev->spi = NULL;
747         spin_unlock_irq(&spidev->spi_lock);
748 
749         /* prevent new opens */
750         mutex_lock(&device_list_lock);
751         list_del(&spidev->device_entry);
752         device_destroy(spidev_class, spidev->devt);
753         clear_bit(MINOR(spidev->devt), minors);
754         if (spidev->users == 0)
755                 kfree(spidev);
756         mutex_unlock(&device_list_lock);
757 
758         return 0;
759 }
760 
761 static const struct of_device_id spidev_dt_ids[] = {
762         { .compatible = "rohm,dh2228fv" },
763         {},
764 };
765 
766 MODULE_DEVICE_TABLE(of, spidev_dt_ids);
767 
768 static struct spi_driver spidev_spi_driver = {
769         .driver = {
770                 .name =         "spidev",
771                 .owner =        THIS_MODULE,
772                 .of_match_table = of_match_ptr(spidev_dt_ids),
773         },
774         .probe =        spidev_probe,
775         .remove =       spidev_remove,
776 
777         /* NOTE:  suspend/resume methods are not necessary here.
778          * We don't do anything except pass the requests to/from
779          * the underlying controller.  The refrigerator handles
780          * most issues; the controller driver handles the rest.
781          */
782 };
783 
784 /*-------------------------------------------------------------------------*/
785 
786 static int __init spidev_init(void)
787 {
788         int status;
789 
790         /* Claim our 256 reserved device numbers.  Then register a class
791          * that will key udev/mdev to add/remove /dev nodes.  Last, register
792          * the driver which manages those device numbers.
793          */
794         BUILD_BUG_ON(N_SPI_MINORS > 256);
795         status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);
796         if (status < 0)
797                 return status;
798 
799         spidev_class = class_create(THIS_MODULE, "spidev");
800         if (IS_ERR(spidev_class)) {
801                 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
802                 return PTR_ERR(spidev_class);
803         }
804 
805         status = spi_register_driver(&spidev_spi_driver);
806         if (status < 0) {
807                 class_destroy(spidev_class);
808                 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
809         }
810         return status;
811 }
812 module_init(spidev_init);
813 
814 static void __exit spidev_exit(void)
815 {
816         spi_unregister_driver(&spidev_spi_driver);
817         class_destroy(spidev_class);
818         unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
819 }
820 module_exit(spidev_exit);
821 
822 MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>");
823 MODULE_DESCRIPTION("User mode SPI device interface");
824 MODULE_LICENSE("GPL");
825 MODULE_ALIAS("spi:spidev");
826 

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