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.
19 #include <linux/init.h>
20 #include <linux/module.h>
21 #include <linux/ioctl.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>
31 #include <linux/of_device.h>
32 #include <linux/acpi.h>
34 #include <linux/spi/spi.h>
35 #include <linux/spi/spidev.h>
37 #include <linux/uaccess.h>
41 * This supports access to SPI devices using normal userspace I/O calls.
42 * Note that while traditional UNIX/POSIX I/O semantics are half duplex,
43 * and often mask message boundaries, full SPI support requires full duplex
44 * transfers. There are several kinds of internal message boundaries to
45 * handle chipselect management and other protocol options.
47 * SPI has a character major number assigned. We allocate minor numbers
48 * dynamically using a bitmask. You must use hotplug tools, such as udev
49 * (or mdev with busybox) to create and destroy the /dev/spidevB.C device
50 * nodes, since there is no fixed association of minor numbers with any
51 * particular SPI bus or device.
53 #define SPIDEV_MAJOR 153 /* assigned */
54 #define N_SPI_MINORS 32 /* ... up to 256 */
56 static DECLARE_BITMAP(minors
, N_SPI_MINORS
);
59 /* Bit masks for spi_device.mode management. Note that incorrect
60 * settings for some settings can cause *lots* of trouble for other
61 * devices on a shared bus:
63 * - CS_HIGH ... this device will be active when it shouldn't be
64 * - 3WIRE ... when active, it won't behave as it should
65 * - NO_CS ... there will be no explicit message boundaries; this
66 * is completely incompatible with the shared bus model
67 * - READY ... transfers may proceed when they shouldn't.
69 * REVISIT should changing those flags be privileged?
71 #define SPI_MODE_MASK (SPI_CPHA | SPI_CPOL | SPI_CS_HIGH \
72 | SPI_LSB_FIRST | SPI_3WIRE | SPI_LOOP \
73 | SPI_NO_CS | SPI_READY | SPI_TX_DUAL \
74 | SPI_TX_QUAD | SPI_RX_DUAL | SPI_RX_QUAD)
79 struct spi_device
*spi
;
80 struct list_head device_entry
;
82 /* TX/RX buffers are NULL unless this device is open (users > 0) */
83 struct mutex buf_lock
;
90 static LIST_HEAD(device_list
);
91 static DEFINE_MUTEX(device_list_lock
);
93 static unsigned bufsiz
= 4096;
94 module_param(bufsiz
, uint
, S_IRUGO
);
95 MODULE_PARM_DESC(bufsiz
, "data bytes in biggest supported SPI message");
97 /*-------------------------------------------------------------------------*/
100 spidev_sync(struct spidev_data
*spidev
, struct spi_message
*message
)
103 struct spi_device
*spi
;
105 spin_lock_irq(&spidev
->spi_lock
);
107 spin_unlock_irq(&spidev
->spi_lock
);
112 status
= spi_sync(spi
, message
);
115 status
= message
->actual_length
;
120 static inline ssize_t
121 spidev_sync_write(struct spidev_data
*spidev
, size_t len
)
123 struct spi_transfer t
= {
124 .tx_buf
= spidev
->tx_buffer
,
126 .speed_hz
= spidev
->speed_hz
,
128 struct spi_message m
;
130 spi_message_init(&m
);
131 spi_message_add_tail(&t
, &m
);
132 return spidev_sync(spidev
, &m
);
135 static inline ssize_t
136 spidev_sync_read(struct spidev_data
*spidev
, size_t len
)
138 struct spi_transfer t
= {
139 .rx_buf
= spidev
->rx_buffer
,
141 .speed_hz
= spidev
->speed_hz
,
143 struct spi_message m
;
145 spi_message_init(&m
);
146 spi_message_add_tail(&t
, &m
);
147 return spidev_sync(spidev
, &m
);
150 /*-------------------------------------------------------------------------*/
152 /* Read-only message with current device setup */
154 spidev_read(struct file
*filp
, char __user
*buf
, size_t count
, loff_t
*f_pos
)
156 struct spidev_data
*spidev
;
159 /* chipselect only toggles at start or end of operation */
163 spidev
= filp
->private_data
;
165 mutex_lock(&spidev
->buf_lock
);
166 status
= spidev_sync_read(spidev
, count
);
168 unsigned long missing
;
170 missing
= copy_to_user(buf
, spidev
->rx_buffer
, status
);
171 if (missing
== status
)
174 status
= status
- missing
;
176 mutex_unlock(&spidev
->buf_lock
);
181 /* Write-only message with current device setup */
183 spidev_write(struct file
*filp
, const char __user
*buf
,
184 size_t count
, loff_t
*f_pos
)
186 struct spidev_data
*spidev
;
188 unsigned long missing
;
190 /* chipselect only toggles at start or end of operation */
194 spidev
= filp
->private_data
;
196 mutex_lock(&spidev
->buf_lock
);
197 missing
= copy_from_user(spidev
->tx_buffer
, buf
, count
);
199 status
= spidev_sync_write(spidev
, count
);
202 mutex_unlock(&spidev
->buf_lock
);
207 static int spidev_message(struct spidev_data
*spidev
,
208 struct spi_ioc_transfer
*u_xfers
, unsigned n_xfers
)
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
;
216 int status
= -EFAULT
;
218 spi_message_init(&msg
);
219 k_xfers
= kcalloc(n_xfers
, sizeof(*k_tmp
), GFP_KERNEL
);
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.
227 tx_buf
= spidev
->tx_buffer
;
228 rx_buf
= spidev
->rx_buffer
;
232 for (n
= n_xfers
, k_tmp
= k_xfers
, u_tmp
= u_xfers
;
234 n
--, k_tmp
++, u_tmp
++) {
235 k_tmp
->len
= u_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.
243 if (total
> INT_MAX
|| k_tmp
->len
> INT_MAX
) {
249 /* this transfer needs space in RX bounce buffer */
250 rx_total
+= k_tmp
->len
;
251 if (rx_total
> bufsiz
) {
255 k_tmp
->rx_buf
= rx_buf
;
256 if (!access_ok(VERIFY_WRITE
, (u8 __user
*)
257 (uintptr_t) u_tmp
->rx_buf
,
260 rx_buf
+= k_tmp
->len
;
263 /* this transfer needs space in TX bounce buffer */
264 tx_total
+= k_tmp
->len
;
265 if (tx_total
> bufsiz
) {
269 k_tmp
->tx_buf
= tx_buf
;
270 if (copy_from_user(tx_buf
, (const u8 __user
*)
271 (uintptr_t) u_tmp
->tx_buf
,
274 tx_buf
+= k_tmp
->len
;
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
;
286 dev_dbg(&spidev
->spi
->dev
,
287 " xfer len %u %s%s%s%dbits %u usec %uHz\n",
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
,
294 u_tmp
->speed_hz
? : spidev
->spi
->max_speed_hz
);
296 spi_message_add_tail(k_tmp
, &msg
);
299 status
= spidev_sync(spidev
, &msg
);
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
++) {
307 if (__copy_to_user((u8 __user
*)
308 (uintptr_t) u_tmp
->rx_buf
, rx_buf
,
313 rx_buf
+= u_tmp
->len
;
323 static struct spi_ioc_transfer
*
324 spidev_get_ioc_message(unsigned int cmd
, struct spi_ioc_transfer __user
*u_ioc
,
329 /* Check type, command number and direction */
330 if (_IOC_TYPE(cmd
) != SPI_IOC_MAGIC
331 || _IOC_NR(cmd
) != _IOC_NR(SPI_IOC_MESSAGE(0))
332 || _IOC_DIR(cmd
) != _IOC_WRITE
)
333 return ERR_PTR(-ENOTTY
);
335 tmp
= _IOC_SIZE(cmd
);
336 if ((tmp
% sizeof(struct spi_ioc_transfer
)) != 0)
337 return ERR_PTR(-EINVAL
);
338 *n_ioc
= tmp
/ sizeof(struct spi_ioc_transfer
);
342 /* copy into scratch area */
343 return memdup_user(u_ioc
, tmp
);
347 spidev_ioctl(struct file
*filp
, unsigned int cmd
, unsigned long arg
)
351 struct spidev_data
*spidev
;
352 struct spi_device
*spi
;
355 struct spi_ioc_transfer
*ioc
;
357 /* Check type and command number */
358 if (_IOC_TYPE(cmd
) != SPI_IOC_MAGIC
)
361 /* Check access direction once here; don't repeat below.
362 * IOC_DIR is from the user perspective, while access_ok is
363 * from the kernel perspective; so they look reversed.
365 if (_IOC_DIR(cmd
) & _IOC_READ
)
366 err
= !access_ok(VERIFY_WRITE
,
367 (void __user
*)arg
, _IOC_SIZE(cmd
));
368 if (err
== 0 && _IOC_DIR(cmd
) & _IOC_WRITE
)
369 err
= !access_ok(VERIFY_READ
,
370 (void __user
*)arg
, _IOC_SIZE(cmd
));
374 /* guard against device removal before, or while,
375 * we issue this ioctl.
377 spidev
= filp
->private_data
;
378 spin_lock_irq(&spidev
->spi_lock
);
379 spi
= spi_dev_get(spidev
->spi
);
380 spin_unlock_irq(&spidev
->spi_lock
);
385 /* use the buffer lock here for triple duty:
386 * - prevent I/O (from us) so calling spi_setup() is safe;
387 * - prevent concurrent SPI_IOC_WR_* from morphing
388 * data fields while SPI_IOC_RD_* reads them;
389 * - SPI_IOC_MESSAGE needs the buffer locked "normally".
391 mutex_lock(&spidev
->buf_lock
);
395 case SPI_IOC_RD_MODE
:
396 retval
= __put_user(spi
->mode
& SPI_MODE_MASK
,
399 case SPI_IOC_RD_MODE32
:
400 retval
= __put_user(spi
->mode
& SPI_MODE_MASK
,
401 (__u32 __user
*)arg
);
403 case SPI_IOC_RD_LSB_FIRST
:
404 retval
= __put_user((spi
->mode
& SPI_LSB_FIRST
) ? 1 : 0,
407 case SPI_IOC_RD_BITS_PER_WORD
:
408 retval
= __put_user(spi
->bits_per_word
, (__u8 __user
*)arg
);
410 case SPI_IOC_RD_MAX_SPEED_HZ
:
411 retval
= __put_user(spidev
->speed_hz
, (__u32 __user
*)arg
);
415 case SPI_IOC_WR_MODE
:
416 case SPI_IOC_WR_MODE32
:
417 if (cmd
== SPI_IOC_WR_MODE
)
418 retval
= __get_user(tmp
, (u8 __user
*)arg
);
420 retval
= __get_user(tmp
, (u32 __user
*)arg
);
422 u32 save
= spi
->mode
;
424 if (tmp
& ~SPI_MODE_MASK
) {
429 tmp
|= spi
->mode
& ~SPI_MODE_MASK
;
430 spi
->mode
= (u16
)tmp
;
431 retval
= spi_setup(spi
);
435 dev_dbg(&spi
->dev
, "spi mode %x\n", tmp
);
438 case SPI_IOC_WR_LSB_FIRST
:
439 retval
= __get_user(tmp
, (__u8 __user
*)arg
);
441 u32 save
= spi
->mode
;
444 spi
->mode
|= SPI_LSB_FIRST
;
446 spi
->mode
&= ~SPI_LSB_FIRST
;
447 retval
= spi_setup(spi
);
451 dev_dbg(&spi
->dev
, "%csb first\n",
455 case SPI_IOC_WR_BITS_PER_WORD
:
456 retval
= __get_user(tmp
, (__u8 __user
*)arg
);
458 u8 save
= spi
->bits_per_word
;
460 spi
->bits_per_word
= tmp
;
461 retval
= spi_setup(spi
);
463 spi
->bits_per_word
= save
;
465 dev_dbg(&spi
->dev
, "%d bits per word\n", tmp
);
468 case SPI_IOC_WR_MAX_SPEED_HZ
:
469 retval
= __get_user(tmp
, (__u32 __user
*)arg
);
471 u32 save
= spi
->max_speed_hz
;
473 spi
->max_speed_hz
= tmp
;
474 retval
= spi_setup(spi
);
476 spidev
->speed_hz
= tmp
;
478 dev_dbg(&spi
->dev
, "%d Hz (max)\n", tmp
);
479 spi
->max_speed_hz
= save
;
484 /* segmented and/or full-duplex I/O request */
485 /* Check message and copy into scratch area */
486 ioc
= spidev_get_ioc_message(cmd
,
487 (struct spi_ioc_transfer __user
*)arg
, &n_ioc
);
489 retval
= PTR_ERR(ioc
);
493 break; /* n_ioc is also 0 */
495 /* translate to spi_message, execute */
496 retval
= spidev_message(spidev
, ioc
, n_ioc
);
501 mutex_unlock(&spidev
->buf_lock
);
508 spidev_compat_ioc_message(struct file
*filp
, unsigned int cmd
,
511 struct spi_ioc_transfer __user
*u_ioc
;
513 struct spidev_data
*spidev
;
514 struct spi_device
*spi
;
516 struct spi_ioc_transfer
*ioc
;
518 u_ioc
= (struct spi_ioc_transfer __user
*) compat_ptr(arg
);
519 if (!access_ok(VERIFY_READ
, u_ioc
, _IOC_SIZE(cmd
)))
522 /* guard against device removal before, or while,
523 * we issue this ioctl.
525 spidev
= filp
->private_data
;
526 spin_lock_irq(&spidev
->spi_lock
);
527 spi
= spi_dev_get(spidev
->spi
);
528 spin_unlock_irq(&spidev
->spi_lock
);
533 /* SPI_IOC_MESSAGE needs the buffer locked "normally" */
534 mutex_lock(&spidev
->buf_lock
);
536 /* Check message and copy into scratch area */
537 ioc
= spidev_get_ioc_message(cmd
, u_ioc
, &n_ioc
);
539 retval
= PTR_ERR(ioc
);
543 goto done
; /* n_ioc is also 0 */
545 /* Convert buffer pointers */
546 for (n
= 0; n
< n_ioc
; n
++) {
547 ioc
[n
].rx_buf
= (uintptr_t) compat_ptr(ioc
[n
].rx_buf
);
548 ioc
[n
].tx_buf
= (uintptr_t) compat_ptr(ioc
[n
].tx_buf
);
551 /* translate to spi_message, execute */
552 retval
= spidev_message(spidev
, ioc
, n_ioc
);
556 mutex_unlock(&spidev
->buf_lock
);
562 spidev_compat_ioctl(struct file
*filp
, unsigned int cmd
, unsigned long arg
)
564 if (_IOC_TYPE(cmd
) == SPI_IOC_MAGIC
565 && _IOC_NR(cmd
) == _IOC_NR(SPI_IOC_MESSAGE(0))
566 && _IOC_DIR(cmd
) == _IOC_WRITE
)
567 return spidev_compat_ioc_message(filp
, cmd
, arg
);
569 return spidev_ioctl(filp
, cmd
, (unsigned long)compat_ptr(arg
));
572 #define spidev_compat_ioctl NULL
573 #endif /* CONFIG_COMPAT */
575 static int spidev_open(struct inode
*inode
, struct file
*filp
)
577 struct spidev_data
*spidev
;
580 mutex_lock(&device_list_lock
);
582 list_for_each_entry(spidev
, &device_list
, device_entry
) {
583 if (spidev
->devt
== inode
->i_rdev
) {
590 pr_debug("spidev: nothing for minor %d\n", iminor(inode
));
594 if (!spidev
->tx_buffer
) {
595 spidev
->tx_buffer
= kmalloc(bufsiz
, GFP_KERNEL
);
596 if (!spidev
->tx_buffer
) {
597 dev_dbg(&spidev
->spi
->dev
, "open/ENOMEM\n");
603 if (!spidev
->rx_buffer
) {
604 spidev
->rx_buffer
= kmalloc(bufsiz
, GFP_KERNEL
);
605 if (!spidev
->rx_buffer
) {
606 dev_dbg(&spidev
->spi
->dev
, "open/ENOMEM\n");
608 goto err_alloc_rx_buf
;
613 filp
->private_data
= spidev
;
614 nonseekable_open(inode
, filp
);
616 mutex_unlock(&device_list_lock
);
620 kfree(spidev
->tx_buffer
);
621 spidev
->tx_buffer
= NULL
;
623 mutex_unlock(&device_list_lock
);
627 static int spidev_release(struct inode
*inode
, struct file
*filp
)
629 struct spidev_data
*spidev
;
631 mutex_lock(&device_list_lock
);
632 spidev
= filp
->private_data
;
633 filp
->private_data
= NULL
;
637 if (!spidev
->users
) {
640 kfree(spidev
->tx_buffer
);
641 spidev
->tx_buffer
= NULL
;
643 kfree(spidev
->rx_buffer
);
644 spidev
->rx_buffer
= NULL
;
646 spin_lock_irq(&spidev
->spi_lock
);
648 spidev
->speed_hz
= spidev
->spi
->max_speed_hz
;
650 /* ... after we unbound from the underlying device? */
651 dofree
= (spidev
->spi
== NULL
);
652 spin_unlock_irq(&spidev
->spi_lock
);
657 mutex_unlock(&device_list_lock
);
662 static const struct file_operations spidev_fops
= {
663 .owner
= THIS_MODULE
,
664 /* REVISIT switch to aio primitives, so that userspace
665 * gets more complete API coverage. It'll simplify things
666 * too, except for the locking.
668 .write
= spidev_write
,
670 .unlocked_ioctl
= spidev_ioctl
,
671 .compat_ioctl
= spidev_compat_ioctl
,
673 .release
= spidev_release
,
677 /*-------------------------------------------------------------------------*/
679 /* The main reason to have this class is to make mdev/udev create the
680 * /dev/spidevB.C character device nodes exposing our userspace API.
681 * It also simplifies memory management.
684 static struct class *spidev_class
;
687 static const struct of_device_id spidev_dt_ids
[] = {
688 { .compatible
= "rohm,dh2228fv" },
689 { .compatible
= "lineartechnology,ltc2488" },
690 { .compatible
= "ge,achc" },
691 { .compatible
= "semtech,sx1301" },
694 MODULE_DEVICE_TABLE(of
, spidev_dt_ids
);
699 /* Dummy SPI devices not to be used in production systems */
700 #define SPIDEV_ACPI_DUMMY 1
702 static const struct acpi_device_id spidev_acpi_ids
[] = {
704 * The ACPI SPT000* devices are only meant for development and
705 * testing. Systems used in production should have a proper ACPI
706 * description of the connected peripheral and they should also use
707 * a proper driver instead of poking directly to the SPI bus.
709 { "SPT0001", SPIDEV_ACPI_DUMMY
},
710 { "SPT0002", SPIDEV_ACPI_DUMMY
},
711 { "SPT0003", SPIDEV_ACPI_DUMMY
},
714 MODULE_DEVICE_TABLE(acpi
, spidev_acpi_ids
);
716 static void spidev_probe_acpi(struct spi_device
*spi
)
718 const struct acpi_device_id
*id
;
720 if (!has_acpi_companion(&spi
->dev
))
723 id
= acpi_match_device(spidev_acpi_ids
, &spi
->dev
);
727 if (id
->driver_data
== SPIDEV_ACPI_DUMMY
)
728 dev_warn(&spi
->dev
, "do not use this driver in production systems!\n");
731 static inline void spidev_probe_acpi(struct spi_device
*spi
) {}
734 /*-------------------------------------------------------------------------*/
736 static int spidev_probe(struct spi_device
*spi
)
738 struct spidev_data
*spidev
;
743 * spidev should never be referenced in DT without a specific
744 * compatible string, it is a Linux implementation thing
745 * rather than a description of the hardware.
747 if (spi
->dev
.of_node
&& !of_match_device(spidev_dt_ids
, &spi
->dev
)) {
748 dev_err(&spi
->dev
, "buggy DT: spidev listed directly in DT\n");
749 WARN_ON(spi
->dev
.of_node
&&
750 !of_match_device(spidev_dt_ids
, &spi
->dev
));
753 spidev_probe_acpi(spi
);
755 /* Allocate driver data */
756 spidev
= kzalloc(sizeof(*spidev
), GFP_KERNEL
);
760 /* Initialize the driver data */
762 spin_lock_init(&spidev
->spi_lock
);
763 mutex_init(&spidev
->buf_lock
);
765 INIT_LIST_HEAD(&spidev
->device_entry
);
767 /* If we can allocate a minor number, hook up this device.
768 * Reusing minors is fine so long as udev or mdev is working.
770 mutex_lock(&device_list_lock
);
771 minor
= find_first_zero_bit(minors
, N_SPI_MINORS
);
772 if (minor
< N_SPI_MINORS
) {
775 spidev
->devt
= MKDEV(SPIDEV_MAJOR
, minor
);
776 dev
= device_create(spidev_class
, &spi
->dev
, spidev
->devt
,
777 spidev
, "spidev%d.%d",
778 spi
->master
->bus_num
, spi
->chip_select
);
779 status
= PTR_ERR_OR_ZERO(dev
);
781 dev_dbg(&spi
->dev
, "no minor number available!\n");
785 set_bit(minor
, minors
);
786 list_add(&spidev
->device_entry
, &device_list
);
788 mutex_unlock(&device_list_lock
);
790 spidev
->speed_hz
= spi
->max_speed_hz
;
793 spi_set_drvdata(spi
, spidev
);
800 static int spidev_remove(struct spi_device
*spi
)
802 struct spidev_data
*spidev
= spi_get_drvdata(spi
);
804 /* make sure ops on existing fds can abort cleanly */
805 spin_lock_irq(&spidev
->spi_lock
);
807 spin_unlock_irq(&spidev
->spi_lock
);
809 /* prevent new opens */
810 mutex_lock(&device_list_lock
);
811 list_del(&spidev
->device_entry
);
812 device_destroy(spidev_class
, spidev
->devt
);
813 clear_bit(MINOR(spidev
->devt
), minors
);
814 if (spidev
->users
== 0)
816 mutex_unlock(&device_list_lock
);
821 static struct spi_driver spidev_spi_driver
= {
824 .of_match_table
= of_match_ptr(spidev_dt_ids
),
825 .acpi_match_table
= ACPI_PTR(spidev_acpi_ids
),
827 .probe
= spidev_probe
,
828 .remove
= spidev_remove
,
830 /* NOTE: suspend/resume methods are not necessary here.
831 * We don't do anything except pass the requests to/from
832 * the underlying controller. The refrigerator handles
833 * most issues; the controller driver handles the rest.
837 /*-------------------------------------------------------------------------*/
839 static int __init
spidev_init(void)
843 /* Claim our 256 reserved device numbers. Then register a class
844 * that will key udev/mdev to add/remove /dev nodes. Last, register
845 * the driver which manages those device numbers.
847 BUILD_BUG_ON(N_SPI_MINORS
> 256);
848 status
= register_chrdev(SPIDEV_MAJOR
, "spi", &spidev_fops
);
852 spidev_class
= class_create(THIS_MODULE
, "spidev");
853 if (IS_ERR(spidev_class
)) {
854 unregister_chrdev(SPIDEV_MAJOR
, spidev_spi_driver
.driver
.name
);
855 return PTR_ERR(spidev_class
);
858 status
= spi_register_driver(&spidev_spi_driver
);
860 class_destroy(spidev_class
);
861 unregister_chrdev(SPIDEV_MAJOR
, spidev_spi_driver
.driver
.name
);
865 module_init(spidev_init
);
867 static void __exit
spidev_exit(void)
869 spi_unregister_driver(&spidev_spi_driver
);
870 class_destroy(spidev_class
);
871 unregister_chrdev(SPIDEV_MAJOR
, spidev_spi_driver
.driver
.name
);
873 module_exit(spidev_exit
);
875 MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>");
876 MODULE_DESCRIPTION("User mode SPI device interface");
877 MODULE_LICENSE("GPL");
878 MODULE_ALIAS("spi:spidev");