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;
226 unsigned n, total, tx_total, rx_total;
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;
244 for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers;
246 n--, k_tmp++, u_tmp++) {
247 k_tmp->len = u_tmp->len;
250 /* Since the function returns the total length of transfers
251 * on success, restrict the total to positive int values to
252 * avoid the return value looking like an error. Also check
253 * each transfer length to avoid arithmetic overflow.
255 if (total > INT_MAX || k_tmp->len > INT_MAX) {
261 /* this transfer needs space in RX bounce buffer */
262 rx_total += k_tmp->len;
263 if (rx_total > bufsiz) {
267 k_tmp->rx_buf = rx_buf;
268 if (!access_ok(VERIFY_WRITE, (u8 __user *)
269 (uintptr_t) u_tmp->rx_buf,
272 rx_buf += k_tmp->len;
275 /* this transfer needs space in TX bounce buffer */
276 tx_total += k_tmp->len;
277 if (tx_total > bufsiz) {
281 k_tmp->tx_buf = tx_buf;
282 if (copy_from_user(tx_buf, (const u8 __user *)
283 (uintptr_t) u_tmp->tx_buf,
286 tx_buf += k_tmp->len;
289 k_tmp->cs_change = !!u_tmp->cs_change;
290 k_tmp->tx_nbits = u_tmp->tx_nbits;
291 k_tmp->rx_nbits = u_tmp->rx_nbits;
292 k_tmp->bits_per_word = u_tmp->bits_per_word;
293 k_tmp->delay_usecs = u_tmp->delay_usecs;
294 k_tmp->speed_hz = u_tmp->speed_hz;
295 if (!k_tmp->speed_hz)
296 k_tmp->speed_hz = spidev->speed_hz;
298 dev_dbg(&spidev->spi->dev,
299 " xfer len %zd %s%s%s%dbits %u usec %uHz\n",
301 u_tmp->rx_buf ? "rx " : "",
302 u_tmp->tx_buf ? "tx " : "",
303 u_tmp->cs_change ? "cs " : "",
304 u_tmp->bits_per_word ? : spidev->spi->bits_per_word,
306 u_tmp->speed_hz ? : spidev->spi->max_speed_hz);
308 spi_message_add_tail(k_tmp, &msg);
311 status = spidev_sync(spidev, &msg);
315 /* copy any rx data out of bounce buffer */
316 rx_buf = spidev->rx_buffer;
317 for (n = n_xfers, u_tmp = u_xfers; n; n--, u_tmp++) {
319 if (__copy_to_user((u8 __user *)
320 (uintptr_t) u_tmp->rx_buf, rx_buf,
325 rx_buf += u_tmp->len;
335 static struct spi_ioc_transfer *
336 spidev_get_ioc_message(unsigned int cmd, struct spi_ioc_transfer __user *u_ioc,
339 struct spi_ioc_transfer *ioc;
342 /* Check type, command number and direction */
343 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC
344 || _IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0))
345 || _IOC_DIR(cmd) != _IOC_WRITE)
346 return ERR_PTR(-ENOTTY);
348 tmp = _IOC_SIZE(cmd);
349 if ((tmp % sizeof(struct spi_ioc_transfer)) != 0)
350 return ERR_PTR(-EINVAL);
351 *n_ioc = tmp / sizeof(struct spi_ioc_transfer);
355 /* copy into scratch area */
356 ioc = kmalloc(tmp, GFP_KERNEL);
358 return ERR_PTR(-ENOMEM);
359 if (__copy_from_user(ioc, u_ioc, tmp)) {
361 return ERR_PTR(-EFAULT);
367 spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
371 struct spidev_data *spidev;
372 struct spi_device *spi;
375 struct spi_ioc_transfer *ioc;
377 /* Check type and command number */
378 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC)
381 /* Check access direction once here; don't repeat below.
382 * IOC_DIR is from the user perspective, while access_ok is
383 * from the kernel perspective; so they look reversed.
385 if (_IOC_DIR(cmd) & _IOC_READ)
386 err = !access_ok(VERIFY_WRITE,
387 (void __user *)arg, _IOC_SIZE(cmd));
388 if (err == 0 && _IOC_DIR(cmd) & _IOC_WRITE)
389 err = !access_ok(VERIFY_READ,
390 (void __user *)arg, _IOC_SIZE(cmd));
394 /* guard against device removal before, or while,
395 * we issue this ioctl.
397 spidev = filp->private_data;
398 spin_lock_irq(&spidev->spi_lock);
399 spi = spi_dev_get(spidev->spi);
400 spin_unlock_irq(&spidev->spi_lock);
405 /* use the buffer lock here for triple duty:
406 * - prevent I/O (from us) so calling spi_setup() is safe;
407 * - prevent concurrent SPI_IOC_WR_* from morphing
408 * data fields while SPI_IOC_RD_* reads them;
409 * - SPI_IOC_MESSAGE needs the buffer locked "normally".
411 mutex_lock(&spidev->buf_lock);
415 case SPI_IOC_RD_MODE:
416 retval = __put_user(spi->mode & SPI_MODE_MASK,
419 case SPI_IOC_RD_MODE32:
420 retval = __put_user(spi->mode & SPI_MODE_MASK,
421 (__u32 __user *)arg);
423 case SPI_IOC_RD_LSB_FIRST:
424 retval = __put_user((spi->mode & SPI_LSB_FIRST) ? 1 : 0,
427 case SPI_IOC_RD_BITS_PER_WORD:
428 retval = __put_user(spi->bits_per_word, (__u8 __user *)arg);
430 case SPI_IOC_RD_MAX_SPEED_HZ:
431 retval = __put_user(spidev->speed_hz, (__u32 __user *)arg);
435 case SPI_IOC_WR_MODE:
436 case SPI_IOC_WR_MODE32:
437 if (cmd == SPI_IOC_WR_MODE)
438 retval = __get_user(tmp, (u8 __user *)arg);
440 retval = __get_user(tmp, (u32 __user *)arg);
442 u32 save = spi->mode;
444 if (tmp & ~SPI_MODE_MASK) {
449 tmp |= spi->mode & ~SPI_MODE_MASK;
450 spi->mode = (u16)tmp;
451 retval = spi_setup(spi);
455 dev_dbg(&spi->dev, "spi mode %x\n", tmp);
458 case SPI_IOC_WR_LSB_FIRST:
459 retval = __get_user(tmp, (__u8 __user *)arg);
461 u32 save = spi->mode;
464 spi->mode |= SPI_LSB_FIRST;
466 spi->mode &= ~SPI_LSB_FIRST;
467 retval = spi_setup(spi);
471 dev_dbg(&spi->dev, "%csb first\n",
475 case SPI_IOC_WR_BITS_PER_WORD:
476 retval = __get_user(tmp, (__u8 __user *)arg);
478 u8 save = spi->bits_per_word;
480 spi->bits_per_word = tmp;
481 retval = spi_setup(spi);
483 spi->bits_per_word = save;
485 dev_dbg(&spi->dev, "%d bits per word\n", tmp);
488 case SPI_IOC_WR_MAX_SPEED_HZ:
489 retval = __get_user(tmp, (__u32 __user *)arg);
491 u32 save = spi->max_speed_hz;
493 spi->max_speed_hz = tmp;
494 retval = spi_setup(spi);
496 spidev->speed_hz = tmp;
498 dev_dbg(&spi->dev, "%d Hz (max)\n", tmp);
499 spi->max_speed_hz = save;
504 /* segmented and/or full-duplex I/O request */
505 /* Check message and copy into scratch area */
506 ioc = spidev_get_ioc_message(cmd,
507 (struct spi_ioc_transfer __user *)arg, &n_ioc);
509 retval = PTR_ERR(ioc);
513 break; /* n_ioc is also 0 */
515 /* translate to spi_message, execute */
516 retval = spidev_message(spidev, ioc, n_ioc);
521 mutex_unlock(&spidev->buf_lock);
528 spidev_compat_ioc_message(struct file *filp, unsigned int cmd,
531 struct spi_ioc_transfer __user *u_ioc;
533 struct spidev_data *spidev;
534 struct spi_device *spi;
536 struct spi_ioc_transfer *ioc;
538 u_ioc = (struct spi_ioc_transfer __user *) compat_ptr(arg);
539 if (!access_ok(VERIFY_READ, u_ioc, _IOC_SIZE(cmd)))
542 /* guard against device removal before, or while,
543 * we issue this ioctl.
545 spidev = filp->private_data;
546 spin_lock_irq(&spidev->spi_lock);
547 spi = spi_dev_get(spidev->spi);
548 spin_unlock_irq(&spidev->spi_lock);
553 /* SPI_IOC_MESSAGE needs the buffer locked "normally" */
554 mutex_lock(&spidev->buf_lock);
556 /* Check message and copy into scratch area */
557 ioc = spidev_get_ioc_message(cmd, u_ioc, &n_ioc);
559 retval = PTR_ERR(ioc);
563 goto done; /* n_ioc is also 0 */
565 /* Convert buffer pointers */
566 for (n = 0; n < n_ioc; n++) {
567 ioc[n].rx_buf = (uintptr_t) compat_ptr(ioc[n].rx_buf);
568 ioc[n].tx_buf = (uintptr_t) compat_ptr(ioc[n].tx_buf);
571 /* translate to spi_message, execute */
572 retval = spidev_message(spidev, ioc, n_ioc);
576 mutex_unlock(&spidev->buf_lock);
582 spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
584 if (_IOC_TYPE(cmd) == SPI_IOC_MAGIC
585 && _IOC_NR(cmd) == _IOC_NR(SPI_IOC_MESSAGE(0))
586 && _IOC_DIR(cmd) == _IOC_WRITE)
587 return spidev_compat_ioc_message(filp, cmd, arg);
589 return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
592 #define spidev_compat_ioctl NULL
593 #endif /* CONFIG_COMPAT */
595 static int spidev_open(struct inode *inode, struct file *filp)
597 struct spidev_data *spidev;
600 mutex_lock(&device_list_lock);
602 list_for_each_entry(spidev, &device_list, device_entry) {
603 if (spidev->devt == inode->i_rdev) {
610 pr_debug("spidev: nothing for minor %d\n", iminor(inode));
614 if (!spidev->tx_buffer) {
615 spidev->tx_buffer = kmalloc(bufsiz, GFP_KERNEL);
616 if (!spidev->tx_buffer) {
617 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
623 if (!spidev->rx_buffer) {
624 spidev->rx_buffer = kmalloc(bufsiz, GFP_KERNEL);
625 if (!spidev->rx_buffer) {
626 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
628 goto err_alloc_rx_buf;
633 filp->private_data = spidev;
634 nonseekable_open(inode, filp);
636 mutex_unlock(&device_list_lock);
640 kfree(spidev->tx_buffer);
641 spidev->tx_buffer = NULL;
643 mutex_unlock(&device_list_lock);
647 static int spidev_release(struct inode *inode, struct file *filp)
649 struct spidev_data *spidev;
652 mutex_lock(&device_list_lock);
653 spidev = filp->private_data;
654 filp->private_data = NULL;
658 if (!spidev->users) {
661 kfree(spidev->tx_buffer);
662 spidev->tx_buffer = NULL;
664 kfree(spidev->rx_buffer);
665 spidev->rx_buffer = NULL;
667 spidev->speed_hz = spidev->spi->max_speed_hz;
669 /* ... after we unbound from the underlying device? */
670 spin_lock_irq(&spidev->spi_lock);
671 dofree = (spidev->spi == NULL);
672 spin_unlock_irq(&spidev->spi_lock);
677 mutex_unlock(&device_list_lock);
682 static const struct file_operations spidev_fops = {
683 .owner = THIS_MODULE,
684 /* REVISIT switch to aio primitives, so that userspace
685 * gets more complete API coverage. It'll simplify things
686 * too, except for the locking.
688 .write = spidev_write,
690 .unlocked_ioctl = spidev_ioctl,
691 .compat_ioctl = spidev_compat_ioctl,
693 .release = spidev_release,
697 /*-------------------------------------------------------------------------*/
699 /* The main reason to have this class is to make mdev/udev create the
700 * /dev/spidevB.C character device nodes exposing our userspace API.
701 * It also simplifies memory management.
704 static struct class *spidev_class;
707 static const struct of_device_id spidev_dt_ids[] = {
708 { .compatible = "rohm,dh2228fv" },
711 MODULE_DEVICE_TABLE(of, spidev_dt_ids);
714 /*-------------------------------------------------------------------------*/
716 static int spidev_probe(struct spi_device *spi)
718 struct spidev_data *spidev;
723 * spidev should never be referenced in DT without a specific
724 * compatbile string, it is a Linux implementation thing
725 * rather than a description of the hardware.
727 if (spi->dev.of_node && !of_match_device(spidev_dt_ids, &spi->dev)) {
728 dev_err(&spi->dev, "buggy DT: spidev listed directly in DT\n");
729 WARN_ON(spi->dev.of_node &&
730 !of_match_device(spidev_dt_ids, &spi->dev));
733 /* Allocate driver data */
734 spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);
738 /* Initialize the driver data */
740 spin_lock_init(&spidev->spi_lock);
741 mutex_init(&spidev->buf_lock);
743 INIT_LIST_HEAD(&spidev->device_entry);
745 /* If we can allocate a minor number, hook up this device.
746 * Reusing minors is fine so long as udev or mdev is working.
748 mutex_lock(&device_list_lock);
749 minor = find_first_zero_bit(minors, N_SPI_MINORS);
750 if (minor < N_SPI_MINORS) {
753 spidev->devt = MKDEV(SPIDEV_MAJOR, minor);
754 dev = device_create(spidev_class, &spi->dev, spidev->devt,
755 spidev, "spidev%d.%d",
756 spi->master->bus_num, spi->chip_select);
757 status = PTR_ERR_OR_ZERO(dev);
759 dev_dbg(&spi->dev, "no minor number available!\n");
763 set_bit(minor, minors);
764 list_add(&spidev->device_entry, &device_list);
766 mutex_unlock(&device_list_lock);
768 spidev->speed_hz = spi->max_speed_hz;
771 spi_set_drvdata(spi, spidev);
778 static int spidev_remove(struct spi_device *spi)
780 struct spidev_data *spidev = spi_get_drvdata(spi);
782 /* make sure ops on existing fds can abort cleanly */
783 spin_lock_irq(&spidev->spi_lock);
785 spin_unlock_irq(&spidev->spi_lock);
787 /* prevent new opens */
788 mutex_lock(&device_list_lock);
789 list_del(&spidev->device_entry);
790 device_destroy(spidev_class, spidev->devt);
791 clear_bit(MINOR(spidev->devt), minors);
792 if (spidev->users == 0)
794 mutex_unlock(&device_list_lock);
799 static struct spi_driver spidev_spi_driver = {
802 .owner = THIS_MODULE,
803 .of_match_table = of_match_ptr(spidev_dt_ids),
805 .probe = spidev_probe,
806 .remove = spidev_remove,
808 /* NOTE: suspend/resume methods are not necessary here.
809 * We don't do anything except pass the requests to/from
810 * the underlying controller. The refrigerator handles
811 * most issues; the controller driver handles the rest.
815 /*-------------------------------------------------------------------------*/
817 static int __init spidev_init(void)
821 /* Claim our 256 reserved device numbers. Then register a class
822 * that will key udev/mdev to add/remove /dev nodes. Last, register
823 * the driver which manages those device numbers.
825 BUILD_BUG_ON(N_SPI_MINORS > 256);
826 status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);
830 spidev_class = class_create(THIS_MODULE, "spidev");
831 if (IS_ERR(spidev_class)) {
832 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
833 return PTR_ERR(spidev_class);
836 status = spi_register_driver(&spidev_spi_driver);
838 class_destroy(spidev_class);
839 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
843 module_init(spidev_init);
845 static void __exit spidev_exit(void)
847 spi_unregister_driver(&spidev_spi_driver);
848 class_destroy(spidev_class);
849 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
851 module_exit(spidev_exit);
853 MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>");
854 MODULE_DESCRIPTION("User mode SPI device interface");
855 MODULE_LICENSE("GPL");
856 MODULE_ALIAS("spi:spidev");