2 * Simple synchronous userspace interface to SPI devices
4 * Copyright (C) 2006 SWAPP
5 * Andrea Paterniani <a.paterniani@swapp-eng.it>
6 * Copyright (C) 2007 David Brownell (simplification, cleanup)
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
23 #include <linux/init.h>
24 #include <linux/module.h>
25 #include <linux/ioctl.h>
27 #include <linux/device.h>
28 #include <linux/err.h>
29 #include <linux/list.h>
30 #include <linux/errno.h>
31 #include <linux/mutex.h>
32 #include <linux/slab.h>
33 #include <linux/compat.h>
35 #include <linux/of_device.h>
37 #include <linux/spi/spi.h>
38 #include <linux/spi/spidev.h>
40 #include <linux/uaccess.h>
44 * This supports access to SPI devices using normal userspace I/O calls.
45 * Note that while traditional UNIX/POSIX I/O semantics are half duplex,
46 * and often mask message boundaries, full SPI support requires full duplex
47 * transfers. There are several kinds of internal message boundaries to
48 * handle chipselect management and other protocol options.
50 * SPI has a character major number assigned. We allocate minor numbers
51 * dynamically using a bitmask. You must use hotplug tools, such as udev
52 * (or mdev with busybox) to create and destroy the /dev/spidevB.C device
53 * nodes, since there is no fixed association of minor numbers with any
54 * particular SPI bus or device.
56 #define SPIDEV_MAJOR 153 /* assigned */
57 #define N_SPI_MINORS 32 /* ... up to 256 */
59 static DECLARE_BITMAP(minors
, N_SPI_MINORS
);
62 /* Bit masks for spi_device.mode management. Note that incorrect
63 * settings for some settings can cause *lots* of trouble for other
64 * devices on a shared bus:
66 * - CS_HIGH ... this device will be active when it shouldn't be
67 * - 3WIRE ... when active, it won't behave as it should
68 * - NO_CS ... there will be no explicit message boundaries; this
69 * is completely incompatible with the shared bus model
70 * - READY ... transfers may proceed when they shouldn't.
72 * REVISIT should changing those flags be privileged?
74 #define SPI_MODE_MASK (SPI_CPHA | SPI_CPOL | SPI_CS_HIGH \
75 | SPI_LSB_FIRST | SPI_3WIRE | SPI_LOOP \
76 | SPI_NO_CS | SPI_READY | SPI_TX_DUAL \
77 | SPI_TX_QUAD | SPI_RX_DUAL | SPI_RX_QUAD)
82 struct spi_device
*spi
;
83 struct list_head device_entry
;
85 /* TX/RX buffers are NULL unless this device is open (users > 0) */
86 struct mutex buf_lock
;
93 static LIST_HEAD(device_list
);
94 static DEFINE_MUTEX(device_list_lock
);
96 static unsigned bufsiz
= 4096;
97 module_param(bufsiz
, uint
, S_IRUGO
);
98 MODULE_PARM_DESC(bufsiz
, "data bytes in biggest supported SPI message");
100 /*-------------------------------------------------------------------------*/
103 * We can't use the standard synchronous wrappers for file I/O; we
104 * need to protect against async removal of the underlying spi_device.
106 static void spidev_complete(void *arg
)
112 spidev_sync(struct spidev_data
*spidev
, struct spi_message
*message
)
114 DECLARE_COMPLETION_ONSTACK(done
);
117 message
->complete
= spidev_complete
;
118 message
->context
= &done
;
120 spin_lock_irq(&spidev
->spi_lock
);
121 if (spidev
->spi
== NULL
)
124 status
= spi_async(spidev
->spi
, message
);
125 spin_unlock_irq(&spidev
->spi_lock
);
128 wait_for_completion(&done
);
129 status
= message
->status
;
131 status
= message
->actual_length
;
136 static inline ssize_t
137 spidev_sync_write(struct spidev_data
*spidev
, size_t len
)
139 struct spi_transfer t
= {
140 .tx_buf
= spidev
->tx_buffer
,
142 .speed_hz
= spidev
->speed_hz
,
144 struct spi_message m
;
146 spi_message_init(&m
);
147 spi_message_add_tail(&t
, &m
);
148 return spidev_sync(spidev
, &m
);
151 static inline ssize_t
152 spidev_sync_read(struct spidev_data
*spidev
, size_t len
)
154 struct spi_transfer t
= {
155 .rx_buf
= spidev
->rx_buffer
,
157 .speed_hz
= spidev
->speed_hz
,
159 struct spi_message m
;
161 spi_message_init(&m
);
162 spi_message_add_tail(&t
, &m
);
163 return spidev_sync(spidev
, &m
);
166 /*-------------------------------------------------------------------------*/
168 /* Read-only message with current device setup */
170 spidev_read(struct file
*filp
, char __user
*buf
, size_t count
, loff_t
*f_pos
)
172 struct spidev_data
*spidev
;
175 /* chipselect only toggles at start or end of operation */
179 spidev
= filp
->private_data
;
181 mutex_lock(&spidev
->buf_lock
);
182 status
= spidev_sync_read(spidev
, count
);
184 unsigned long missing
;
186 missing
= copy_to_user(buf
, spidev
->rx_buffer
, status
);
187 if (missing
== status
)
190 status
= status
- missing
;
192 mutex_unlock(&spidev
->buf_lock
);
197 /* Write-only message with current device setup */
199 spidev_write(struct file
*filp
, const char __user
*buf
,
200 size_t count
, loff_t
*f_pos
)
202 struct spidev_data
*spidev
;
204 unsigned long missing
;
206 /* chipselect only toggles at start or end of operation */
210 spidev
= filp
->private_data
;
212 mutex_lock(&spidev
->buf_lock
);
213 missing
= copy_from_user(spidev
->tx_buffer
, buf
, count
);
215 status
= spidev_sync_write(spidev
, count
);
218 mutex_unlock(&spidev
->buf_lock
);
223 static int spidev_message(struct spidev_data
*spidev
,
224 struct spi_ioc_transfer
*u_xfers
, unsigned n_xfers
)
226 struct spi_message msg
;
227 struct spi_transfer
*k_xfers
;
228 struct spi_transfer
*k_tmp
;
229 struct spi_ioc_transfer
*u_tmp
;
232 int status
= -EFAULT
;
234 spi_message_init(&msg
);
235 k_xfers
= kcalloc(n_xfers
, sizeof(*k_tmp
), GFP_KERNEL
);
239 /* Construct spi_message, copying any tx data to bounce buffer.
240 * We walk the array of user-provided transfers, using each one
241 * to initialize a kernel version of the same transfer.
243 tx_buf
= spidev
->tx_buffer
;
244 rx_buf
= spidev
->rx_buffer
;
246 for (n
= n_xfers
, k_tmp
= k_xfers
, u_tmp
= u_xfers
;
248 n
--, k_tmp
++, u_tmp
++) {
249 k_tmp
->len
= u_tmp
->len
;
252 if (total
> bufsiz
) {
258 k_tmp
->rx_buf
= rx_buf
;
259 if (!access_ok(VERIFY_WRITE
, (u8 __user
*)
260 (uintptr_t) u_tmp
->rx_buf
,
265 k_tmp
->tx_buf
= tx_buf
;
266 if (copy_from_user(tx_buf
, (const u8 __user
*)
267 (uintptr_t) u_tmp
->tx_buf
,
271 tx_buf
+= k_tmp
->len
;
272 rx_buf
+= k_tmp
->len
;
274 k_tmp
->cs_change
= !!u_tmp
->cs_change
;
275 k_tmp
->tx_nbits
= u_tmp
->tx_nbits
;
276 k_tmp
->rx_nbits
= u_tmp
->rx_nbits
;
277 k_tmp
->bits_per_word
= u_tmp
->bits_per_word
;
278 k_tmp
->delay_usecs
= u_tmp
->delay_usecs
;
279 k_tmp
->speed_hz
= u_tmp
->speed_hz
;
280 if (!k_tmp
->speed_hz
)
281 k_tmp
->speed_hz
= spidev
->speed_hz
;
283 dev_dbg(&spidev
->spi
->dev
,
284 " xfer len %zd %s%s%s%dbits %u usec %uHz\n",
286 u_tmp
->rx_buf
? "rx " : "",
287 u_tmp
->tx_buf
? "tx " : "",
288 u_tmp
->cs_change
? "cs " : "",
289 u_tmp
->bits_per_word
? : spidev
->spi
->bits_per_word
,
291 u_tmp
->speed_hz
? : spidev
->spi
->max_speed_hz
);
293 spi_message_add_tail(k_tmp
, &msg
);
296 status
= spidev_sync(spidev
, &msg
);
300 /* copy any rx data out of bounce buffer */
301 rx_buf
= spidev
->rx_buffer
;
302 for (n
= n_xfers
, u_tmp
= u_xfers
; n
; n
--, u_tmp
++) {
304 if (__copy_to_user((u8 __user
*)
305 (uintptr_t) u_tmp
->rx_buf
, rx_buf
,
311 rx_buf
+= u_tmp
->len
;
321 spidev_ioctl(struct file
*filp
, unsigned int cmd
, unsigned long arg
)
325 struct spidev_data
*spidev
;
326 struct spi_device
*spi
;
329 struct spi_ioc_transfer
*ioc
;
331 /* Check type and command number */
332 if (_IOC_TYPE(cmd
) != SPI_IOC_MAGIC
)
335 /* Check access direction once here; don't repeat below.
336 * IOC_DIR is from the user perspective, while access_ok is
337 * from the kernel perspective; so they look reversed.
339 if (_IOC_DIR(cmd
) & _IOC_READ
)
340 err
= !access_ok(VERIFY_WRITE
,
341 (void __user
*)arg
, _IOC_SIZE(cmd
));
342 if (err
== 0 && _IOC_DIR(cmd
) & _IOC_WRITE
)
343 err
= !access_ok(VERIFY_READ
,
344 (void __user
*)arg
, _IOC_SIZE(cmd
));
348 /* guard against device removal before, or while,
349 * we issue this ioctl.
351 spidev
= filp
->private_data
;
352 spin_lock_irq(&spidev
->spi_lock
);
353 spi
= spi_dev_get(spidev
->spi
);
354 spin_unlock_irq(&spidev
->spi_lock
);
359 /* use the buffer lock here for triple duty:
360 * - prevent I/O (from us) so calling spi_setup() is safe;
361 * - prevent concurrent SPI_IOC_WR_* from morphing
362 * data fields while SPI_IOC_RD_* reads them;
363 * - SPI_IOC_MESSAGE needs the buffer locked "normally".
365 mutex_lock(&spidev
->buf_lock
);
369 case SPI_IOC_RD_MODE
:
370 retval
= __put_user(spi
->mode
& SPI_MODE_MASK
,
373 case SPI_IOC_RD_MODE32
:
374 retval
= __put_user(spi
->mode
& SPI_MODE_MASK
,
375 (__u32 __user
*)arg
);
377 case SPI_IOC_RD_LSB_FIRST
:
378 retval
= __put_user((spi
->mode
& SPI_LSB_FIRST
) ? 1 : 0,
381 case SPI_IOC_RD_BITS_PER_WORD
:
382 retval
= __put_user(spi
->bits_per_word
, (__u8 __user
*)arg
);
384 case SPI_IOC_RD_MAX_SPEED_HZ
:
385 retval
= __put_user(spidev
->speed_hz
, (__u32 __user
*)arg
);
389 case SPI_IOC_WR_MODE
:
390 case SPI_IOC_WR_MODE32
:
391 if (cmd
== SPI_IOC_WR_MODE
)
392 retval
= __get_user(tmp
, (u8 __user
*)arg
);
394 retval
= __get_user(tmp
, (u32 __user
*)arg
);
396 u32 save
= spi
->mode
;
398 if (tmp
& ~SPI_MODE_MASK
) {
403 tmp
|= spi
->mode
& ~SPI_MODE_MASK
;
404 spi
->mode
= (u16
)tmp
;
405 retval
= spi_setup(spi
);
409 dev_dbg(&spi
->dev
, "spi mode %x\n", tmp
);
412 case SPI_IOC_WR_LSB_FIRST
:
413 retval
= __get_user(tmp
, (__u8 __user
*)arg
);
415 u32 save
= spi
->mode
;
418 spi
->mode
|= SPI_LSB_FIRST
;
420 spi
->mode
&= ~SPI_LSB_FIRST
;
421 retval
= spi_setup(spi
);
425 dev_dbg(&spi
->dev
, "%csb first\n",
429 case SPI_IOC_WR_BITS_PER_WORD
:
430 retval
= __get_user(tmp
, (__u8 __user
*)arg
);
432 u8 save
= spi
->bits_per_word
;
434 spi
->bits_per_word
= tmp
;
435 retval
= spi_setup(spi
);
437 spi
->bits_per_word
= save
;
439 dev_dbg(&spi
->dev
, "%d bits per word\n", tmp
);
442 case SPI_IOC_WR_MAX_SPEED_HZ
:
443 retval
= __get_user(tmp
, (__u32 __user
*)arg
);
445 u32 save
= spi
->max_speed_hz
;
447 spi
->max_speed_hz
= tmp
;
448 retval
= spi_setup(spi
);
450 spidev
->speed_hz
= tmp
;
452 dev_dbg(&spi
->dev
, "%d Hz (max)\n", tmp
);
453 spi
->max_speed_hz
= save
;
458 /* segmented and/or full-duplex I/O request */
459 if (_IOC_NR(cmd
) != _IOC_NR(SPI_IOC_MESSAGE(0))
460 || _IOC_DIR(cmd
) != _IOC_WRITE
) {
465 tmp
= _IOC_SIZE(cmd
);
466 if ((tmp
% sizeof(struct spi_ioc_transfer
)) != 0) {
470 n_ioc
= tmp
/ sizeof(struct spi_ioc_transfer
);
474 /* copy into scratch area */
475 ioc
= kmalloc(tmp
, GFP_KERNEL
);
480 if (__copy_from_user(ioc
, (void __user
*)arg
, tmp
)) {
486 /* translate to spi_message, execute */
487 retval
= spidev_message(spidev
, ioc
, n_ioc
);
492 mutex_unlock(&spidev
->buf_lock
);
499 spidev_compat_ioctl(struct file
*filp
, unsigned int cmd
, unsigned long arg
)
501 return spidev_ioctl(filp
, cmd
, (unsigned long)compat_ptr(arg
));
504 #define spidev_compat_ioctl NULL
505 #endif /* CONFIG_COMPAT */
507 static int spidev_open(struct inode
*inode
, struct file
*filp
)
509 struct spidev_data
*spidev
;
512 mutex_lock(&device_list_lock
);
514 list_for_each_entry(spidev
, &device_list
, device_entry
) {
515 if (spidev
->devt
== inode
->i_rdev
) {
522 pr_debug("spidev: nothing for minor %d\n", iminor(inode
));
526 if (!spidev
->tx_buffer
) {
527 spidev
->tx_buffer
= kmalloc(bufsiz
, GFP_KERNEL
);
528 if (!spidev
->tx_buffer
) {
529 dev_dbg(&spidev
->spi
->dev
, "open/ENOMEM\n");
535 if (!spidev
->rx_buffer
) {
536 spidev
->rx_buffer
= kmalloc(bufsiz
, GFP_KERNEL
);
537 if (!spidev
->rx_buffer
) {
538 dev_dbg(&spidev
->spi
->dev
, "open/ENOMEM\n");
540 goto err_alloc_rx_buf
;
545 filp
->private_data
= spidev
;
546 nonseekable_open(inode
, filp
);
548 mutex_unlock(&device_list_lock
);
552 kfree(spidev
->tx_buffer
);
553 spidev
->tx_buffer
= NULL
;
555 mutex_unlock(&device_list_lock
);
559 static int spidev_release(struct inode
*inode
, struct file
*filp
)
561 struct spidev_data
*spidev
;
564 mutex_lock(&device_list_lock
);
565 spidev
= filp
->private_data
;
566 filp
->private_data
= NULL
;
570 if (!spidev
->users
) {
573 kfree(spidev
->tx_buffer
);
574 spidev
->tx_buffer
= NULL
;
576 kfree(spidev
->rx_buffer
);
577 spidev
->rx_buffer
= NULL
;
579 spidev
->speed_hz
= spidev
->spi
->max_speed_hz
;
581 /* ... after we unbound from the underlying device? */
582 spin_lock_irq(&spidev
->spi_lock
);
583 dofree
= (spidev
->spi
== NULL
);
584 spin_unlock_irq(&spidev
->spi_lock
);
589 mutex_unlock(&device_list_lock
);
594 static const struct file_operations spidev_fops
= {
595 .owner
= THIS_MODULE
,
596 /* REVISIT switch to aio primitives, so that userspace
597 * gets more complete API coverage. It'll simplify things
598 * too, except for the locking.
600 .write
= spidev_write
,
602 .unlocked_ioctl
= spidev_ioctl
,
603 .compat_ioctl
= spidev_compat_ioctl
,
605 .release
= spidev_release
,
609 /*-------------------------------------------------------------------------*/
611 /* The main reason to have this class is to make mdev/udev create the
612 * /dev/spidevB.C character device nodes exposing our userspace API.
613 * It also simplifies memory management.
616 static struct class *spidev_class
;
618 /*-------------------------------------------------------------------------*/
620 static int spidev_probe(struct spi_device
*spi
)
622 struct spidev_data
*spidev
;
626 /* Allocate driver data */
627 spidev
= kzalloc(sizeof(*spidev
), GFP_KERNEL
);
631 /* Initialize the driver data */
633 spin_lock_init(&spidev
->spi_lock
);
634 mutex_init(&spidev
->buf_lock
);
636 INIT_LIST_HEAD(&spidev
->device_entry
);
638 /* If we can allocate a minor number, hook up this device.
639 * Reusing minors is fine so long as udev or mdev is working.
641 mutex_lock(&device_list_lock
);
642 minor
= find_first_zero_bit(minors
, N_SPI_MINORS
);
643 if (minor
< N_SPI_MINORS
) {
646 spidev
->devt
= MKDEV(SPIDEV_MAJOR
, minor
);
647 dev
= device_create(spidev_class
, &spi
->dev
, spidev
->devt
,
648 spidev
, "spidev%d.%d",
649 spi
->master
->bus_num
, spi
->chip_select
);
650 status
= PTR_ERR_OR_ZERO(dev
);
652 dev_dbg(&spi
->dev
, "no minor number available!\n");
656 set_bit(minor
, minors
);
657 list_add(&spidev
->device_entry
, &device_list
);
659 mutex_unlock(&device_list_lock
);
661 spidev
->speed_hz
= spi
->max_speed_hz
;
664 spi_set_drvdata(spi
, spidev
);
671 static int spidev_remove(struct spi_device
*spi
)
673 struct spidev_data
*spidev
= spi_get_drvdata(spi
);
675 /* make sure ops on existing fds can abort cleanly */
676 spin_lock_irq(&spidev
->spi_lock
);
678 spin_unlock_irq(&spidev
->spi_lock
);
680 /* prevent new opens */
681 mutex_lock(&device_list_lock
);
682 list_del(&spidev
->device_entry
);
683 device_destroy(spidev_class
, spidev
->devt
);
684 clear_bit(MINOR(spidev
->devt
), minors
);
685 if (spidev
->users
== 0)
687 mutex_unlock(&device_list_lock
);
692 static const struct of_device_id spidev_dt_ids
[] = {
693 { .compatible
= "rohm,dh2228fv" },
697 MODULE_DEVICE_TABLE(of
, spidev_dt_ids
);
699 static struct spi_driver spidev_spi_driver
= {
702 .owner
= THIS_MODULE
,
703 .of_match_table
= of_match_ptr(spidev_dt_ids
),
705 .probe
= spidev_probe
,
706 .remove
= spidev_remove
,
708 /* NOTE: suspend/resume methods are not necessary here.
709 * We don't do anything except pass the requests to/from
710 * the underlying controller. The refrigerator handles
711 * most issues; the controller driver handles the rest.
715 /*-------------------------------------------------------------------------*/
717 static int __init
spidev_init(void)
721 /* Claim our 256 reserved device numbers. Then register a class
722 * that will key udev/mdev to add/remove /dev nodes. Last, register
723 * the driver which manages those device numbers.
725 BUILD_BUG_ON(N_SPI_MINORS
> 256);
726 status
= register_chrdev(SPIDEV_MAJOR
, "spi", &spidev_fops
);
730 spidev_class
= class_create(THIS_MODULE
, "spidev");
731 if (IS_ERR(spidev_class
)) {
732 unregister_chrdev(SPIDEV_MAJOR
, spidev_spi_driver
.driver
.name
);
733 return PTR_ERR(spidev_class
);
736 status
= spi_register_driver(&spidev_spi_driver
);
738 class_destroy(spidev_class
);
739 unregister_chrdev(SPIDEV_MAJOR
, spidev_spi_driver
.driver
.name
);
743 module_init(spidev_init
);
745 static void __exit
spidev_exit(void)
747 spi_unregister_driver(&spidev_spi_driver
);
748 class_destroy(spidev_class
);
749 unregister_chrdev(SPIDEV_MAJOR
, spidev_spi_driver
.driver
.name
);
751 module_exit(spidev_exit
);
753 MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>");
754 MODULE_DESCRIPTION("User mode SPI device interface");
755 MODULE_LICENSE("GPL");
756 MODULE_ALIAS("spi:spidev");