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");