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>
33 #include <linux/spi/spi.h>
34 #include <linux/spi/spidev.h>
36 #include <linux/uaccess.h>
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.
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.
52 #define SPIDEV_MAJOR 153 /* assigned */
53 #define N_SPI_MINORS 32 /* ... up to 256 */
55 static DECLARE_BITMAP(minors, N_SPI_MINORS);
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:
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.
68 * REVISIT should changing those flags be privileged?
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)
78 struct spi_device *spi;
79 struct list_head device_entry;
81 /* TX/RX buffers are NULL unless this device is open (users > 0) */
82 struct mutex buf_lock;
89 static LIST_HEAD(device_list);
90 static DEFINE_MUTEX(device_list_lock);
92 static unsigned bufsiz = 4096;
93 module_param(bufsiz, uint, S_IRUGO);
94 MODULE_PARM_DESC(bufsiz, "data bytes in biggest supported SPI message");
96 /*-------------------------------------------------------------------------*/
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.
102 static void spidev_complete(void *arg)
108 spidev_sync(struct spidev_data *spidev, struct spi_message *message)
110 DECLARE_COMPLETION_ONSTACK(done);
113 message->complete = spidev_complete;
114 message->context = &done;
116 spin_lock_irq(&spidev->spi_lock);
117 if (spidev->spi == NULL)
120 status = spi_async(spidev->spi, message);
121 spin_unlock_irq(&spidev->spi_lock);
124 wait_for_completion(&done);
125 status = message->status;
127 status = message->actual_length;
132 static inline ssize_t
133 spidev_sync_write(struct spidev_data *spidev, size_t len)
135 struct spi_transfer t = {
136 .tx_buf = spidev->tx_buffer,
138 .speed_hz = spidev->speed_hz,
140 struct spi_message m;
142 spi_message_init(&m);
143 spi_message_add_tail(&t, &m);
144 return spidev_sync(spidev, &m);
147 static inline ssize_t
148 spidev_sync_read(struct spidev_data *spidev, size_t len)
150 struct spi_transfer t = {
151 .rx_buf = spidev->rx_buffer,
153 .speed_hz = spidev->speed_hz,
155 struct spi_message m;
157 spi_message_init(&m);
158 spi_message_add_tail(&t, &m);
159 return spidev_sync(spidev, &m);
162 /*-------------------------------------------------------------------------*/
164 /* Read-only message with current device setup */
166 spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
168 struct spidev_data *spidev;
171 /* chipselect only toggles at start or end of operation */
175 spidev = filp->private_data;
177 mutex_lock(&spidev->buf_lock);
178 status = spidev_sync_read(spidev, count);
180 unsigned long missing;
182 missing = copy_to_user(buf, spidev->rx_buffer, status);
183 if (missing == status)
186 status = status - missing;
188 mutex_unlock(&spidev->buf_lock);
193 /* Write-only message with current device setup */
195 spidev_write(struct file *filp, const char __user *buf,
196 size_t count, loff_t *f_pos)
198 struct spidev_data *spidev;
200 unsigned long missing;
202 /* chipselect only toggles at start or end of operation */
206 spidev = filp->private_data;
208 mutex_lock(&spidev->buf_lock);
209 missing = copy_from_user(spidev->tx_buffer, buf, count);
211 status = spidev_sync_write(spidev, count);
214 mutex_unlock(&spidev->buf_lock);
219 static int spidev_message(struct spidev_data *spidev,
220 struct spi_ioc_transfer *u_xfers, unsigned n_xfers)
222 struct spi_message msg;
223 struct spi_transfer *k_xfers;
224 struct spi_transfer *k_tmp;
225 struct spi_ioc_transfer *u_tmp;
228 int status = -EFAULT;
230 spi_message_init(&msg);
231 k_xfers = kcalloc(n_xfers, sizeof(*k_tmp), GFP_KERNEL);
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.
239 tx_buf = spidev->tx_buffer;
240 rx_buf = spidev->rx_buffer;
242 for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers;
244 n--, k_tmp++, u_tmp++) {
245 k_tmp->len = u_tmp->len;
248 if (total > bufsiz) {
254 k_tmp->rx_buf = rx_buf;
255 if (!access_ok(VERIFY_WRITE, (u8 __user *)
256 (uintptr_t) u_tmp->rx_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,
267 tx_buf += k_tmp->len;
268 rx_buf += k_tmp->len;
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;
279 dev_dbg(&spidev->spi->dev,
280 " xfer len %zd %s%s%s%dbits %u usec %uHz\n",
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,
287 u_tmp->speed_hz ? : spidev->spi->max_speed_hz);
289 spi_message_add_tail(k_tmp, &msg);
292 status = spidev_sync(spidev, &msg);
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++) {
300 if (__copy_to_user((u8 __user *)
301 (uintptr_t) u_tmp->rx_buf, rx_buf,
307 rx_buf += u_tmp->len;
316 static struct spi_ioc_transfer *
317 spidev_get_ioc_message(unsigned int cmd, struct spi_ioc_transfer __user *u_ioc,
320 struct spi_ioc_transfer *ioc;
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);
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);
336 /* copy into scratch area */
337 ioc = kmalloc(tmp, GFP_KERNEL);
339 return ERR_PTR(-ENOMEM);
340 if (__copy_from_user(ioc, u_ioc, tmp)) {
342 return ERR_PTR(-EFAULT);
348 spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
352 struct spidev_data *spidev;
353 struct spi_device *spi;
356 struct spi_ioc_transfer *ioc;
358 /* Check type and command number */
359 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC)
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.
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));
375 /* guard against device removal before, or while,
376 * we issue this ioctl.
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);
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".
392 mutex_lock(&spidev->buf_lock);
396 case SPI_IOC_RD_MODE:
397 retval = __put_user(spi->mode & SPI_MODE_MASK,
400 case SPI_IOC_RD_MODE32:
401 retval = __put_user(spi->mode & SPI_MODE_MASK,
402 (__u32 __user *)arg);
404 case SPI_IOC_RD_LSB_FIRST:
405 retval = __put_user((spi->mode & SPI_LSB_FIRST) ? 1 : 0,
408 case SPI_IOC_RD_BITS_PER_WORD:
409 retval = __put_user(spi->bits_per_word, (__u8 __user *)arg);
411 case SPI_IOC_RD_MAX_SPEED_HZ:
412 retval = __put_user(spidev->speed_hz, (__u32 __user *)arg);
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);
421 retval = __get_user(tmp, (u32 __user *)arg);
423 u32 save = spi->mode;
425 if (tmp & ~SPI_MODE_MASK) {
430 tmp |= spi->mode & ~SPI_MODE_MASK;
431 spi->mode = (u16)tmp;
432 retval = spi_setup(spi);
436 dev_dbg(&spi->dev, "spi mode %x\n", tmp);
439 case SPI_IOC_WR_LSB_FIRST:
440 retval = __get_user(tmp, (__u8 __user *)arg);
442 u32 save = spi->mode;
445 spi->mode |= SPI_LSB_FIRST;
447 spi->mode &= ~SPI_LSB_FIRST;
448 retval = spi_setup(spi);
452 dev_dbg(&spi->dev, "%csb first\n",
456 case SPI_IOC_WR_BITS_PER_WORD:
457 retval = __get_user(tmp, (__u8 __user *)arg);
459 u8 save = spi->bits_per_word;
461 spi->bits_per_word = tmp;
462 retval = spi_setup(spi);
464 spi->bits_per_word = save;
466 dev_dbg(&spi->dev, "%d bits per word\n", tmp);
469 case SPI_IOC_WR_MAX_SPEED_HZ:
470 retval = __get_user(tmp, (__u32 __user *)arg);
472 u32 save = spi->max_speed_hz;
474 spi->max_speed_hz = tmp;
475 retval = spi_setup(spi);
477 spidev->speed_hz = tmp;
479 dev_dbg(&spi->dev, "%d Hz (max)\n", tmp);
480 spi->max_speed_hz = save;
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);
490 retval = PTR_ERR(ioc);
494 break; /* n_ioc is also 0 */
496 /* translate to spi_message, execute */
497 retval = spidev_message(spidev, ioc, n_ioc);
502 mutex_unlock(&spidev->buf_lock);
509 spidev_compat_ioc_message(struct file *filp, unsigned int cmd,
512 struct spi_ioc_transfer __user *u_ioc;
514 struct spidev_data *spidev;
515 struct spi_device *spi;
517 struct spi_ioc_transfer *ioc;
519 u_ioc = (struct spi_ioc_transfer __user *) compat_ptr(arg);
520 if (!access_ok(VERIFY_READ, u_ioc, _IOC_SIZE(cmd)))
523 /* guard against device removal before, or while,
524 * we issue this ioctl.
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);
534 /* SPI_IOC_MESSAGE needs the buffer locked "normally" */
535 mutex_lock(&spidev->buf_lock);
537 /* Check message and copy into scratch area */
538 ioc = spidev_get_ioc_message(cmd, u_ioc, &n_ioc);
540 retval = PTR_ERR(ioc);
544 goto done; /* n_ioc is also 0 */
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);
552 /* translate to spi_message, execute */
553 retval = spidev_message(spidev, ioc, n_ioc);
557 mutex_unlock(&spidev->buf_lock);
563 spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
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);
570 return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
573 #define spidev_compat_ioctl NULL
574 #endif /* CONFIG_COMPAT */
576 static int spidev_open(struct inode *inode, struct file *filp)
578 struct spidev_data *spidev;
581 mutex_lock(&device_list_lock);
583 list_for_each_entry(spidev, &device_list, device_entry) {
584 if (spidev->devt == inode->i_rdev) {
591 pr_debug("spidev: nothing for minor %d\n", iminor(inode));
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");
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");
609 goto err_alloc_rx_buf;
614 filp->private_data = spidev;
615 nonseekable_open(inode, filp);
617 mutex_unlock(&device_list_lock);
621 kfree(spidev->tx_buffer);
622 spidev->tx_buffer = NULL;
624 mutex_unlock(&device_list_lock);
628 static int spidev_release(struct inode *inode, struct file *filp)
630 struct spidev_data *spidev;
633 mutex_lock(&device_list_lock);
634 spidev = filp->private_data;
635 filp->private_data = NULL;
639 if (!spidev->users) {
642 kfree(spidev->tx_buffer);
643 spidev->tx_buffer = NULL;
645 kfree(spidev->rx_buffer);
646 spidev->rx_buffer = NULL;
648 spidev->speed_hz = spidev->spi->max_speed_hz;
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);
658 mutex_unlock(&device_list_lock);
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.
669 .write = spidev_write,
671 .unlocked_ioctl = spidev_ioctl,
672 .compat_ioctl = spidev_compat_ioctl,
674 .release = spidev_release,
678 /*-------------------------------------------------------------------------*/
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.
685 static struct class *spidev_class;
687 /*-------------------------------------------------------------------------*/
689 static int spidev_probe(struct spi_device *spi)
691 struct spidev_data *spidev;
695 /* Allocate driver data */
696 spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);
700 /* Initialize the driver data */
702 spin_lock_init(&spidev->spi_lock);
703 mutex_init(&spidev->buf_lock);
705 INIT_LIST_HEAD(&spidev->device_entry);
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.
710 mutex_lock(&device_list_lock);
711 minor = find_first_zero_bit(minors, N_SPI_MINORS);
712 if (minor < N_SPI_MINORS) {
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);
721 dev_dbg(&spi->dev, "no minor number available!\n");
725 set_bit(minor, minors);
726 list_add(&spidev->device_entry, &device_list);
728 mutex_unlock(&device_list_lock);
730 spidev->speed_hz = spi->max_speed_hz;
733 spi_set_drvdata(spi, spidev);
740 static int spidev_remove(struct spi_device *spi)
742 struct spidev_data *spidev = spi_get_drvdata(spi);
744 /* make sure ops on existing fds can abort cleanly */
745 spin_lock_irq(&spidev->spi_lock);
747 spin_unlock_irq(&spidev->spi_lock);
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)
756 mutex_unlock(&device_list_lock);
761 static const struct of_device_id spidev_dt_ids[] = {
762 { .compatible = "rohm,dh2228fv" },
766 MODULE_DEVICE_TABLE(of, spidev_dt_ids);
768 static struct spi_driver spidev_spi_driver = {
771 .owner = THIS_MODULE,
772 .of_match_table = of_match_ptr(spidev_dt_ids),
774 .probe = spidev_probe,
775 .remove = spidev_remove,
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.
784 /*-------------------------------------------------------------------------*/
786 static int __init spidev_init(void)
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.
794 BUILD_BUG_ON(N_SPI_MINORS > 256);
795 status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);
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);
805 status = spi_register_driver(&spidev_spi_driver);
807 class_destroy(spidev_class);
808 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
812 module_init(spidev_init);
814 static void __exit spidev_exit(void)
816 spi_unregister_driver(&spidev_spi_driver);
817 class_destroy(spidev_class);
818 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
820 module_exit(spidev_exit);
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");