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 rx_buf += k_tmp->len;
259 /* this transfer needs space in TX bounce buffer */
260 tx_total += k_tmp->len;
261 if (tx_total > bufsiz) {
265 k_tmp->tx_buf = tx_buf;
266 if (copy_from_user(tx_buf, (const u8 __user *)
267 (uintptr_t) u_tmp->tx_buf,
270 tx_buf += k_tmp->len;
273 k_tmp->cs_change = !!u_tmp->cs_change;
274 k_tmp->tx_nbits = u_tmp->tx_nbits;
275 k_tmp->rx_nbits = u_tmp->rx_nbits;
276 k_tmp->bits_per_word = u_tmp->bits_per_word;
277 k_tmp->delay_usecs = u_tmp->delay_usecs;
278 k_tmp->speed_hz = u_tmp->speed_hz;
279 k_tmp->word_delay_usecs = u_tmp->word_delay_usecs;
280 if (!k_tmp->speed_hz)
281 k_tmp->speed_hz = spidev->speed_hz;
283 dev_dbg(&spidev->spi->dev,
284 " xfer len %u %s%s%s%dbits %u usec %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->word_delay_usecs,
292 u_tmp->speed_hz ? : spidev->spi->max_speed_hz);
294 spi_message_add_tail(k_tmp, &msg);
297 status = spidev_sync(spidev, &msg);
301 /* copy any rx data out of bounce buffer */
302 rx_buf = spidev->rx_buffer;
303 for (n = n_xfers, u_tmp = u_xfers; n; n--, u_tmp++) {
305 if (copy_to_user((u8 __user *)
306 (uintptr_t) u_tmp->rx_buf, rx_buf,
311 rx_buf += u_tmp->len;
321 static struct spi_ioc_transfer *
322 spidev_get_ioc_message(unsigned int cmd, struct spi_ioc_transfer __user *u_ioc,
327 /* Check type, command number and direction */
328 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC
329 || _IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0))
330 || _IOC_DIR(cmd) != _IOC_WRITE)
331 return ERR_PTR(-ENOTTY);
333 tmp = _IOC_SIZE(cmd);
334 if ((tmp % sizeof(struct spi_ioc_transfer)) != 0)
335 return ERR_PTR(-EINVAL);
336 *n_ioc = tmp / sizeof(struct spi_ioc_transfer);
340 /* copy into scratch area */
341 return memdup_user(u_ioc, tmp);
345 spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
348 struct spidev_data *spidev;
349 struct spi_device *spi;
352 struct spi_ioc_transfer *ioc;
354 /* Check type and command number */
355 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC)
358 /* guard against device removal before, or while,
359 * we issue this ioctl.
361 spidev = filp->private_data;
362 spin_lock_irq(&spidev->spi_lock);
363 spi = spi_dev_get(spidev->spi);
364 spin_unlock_irq(&spidev->spi_lock);
369 /* use the buffer lock here for triple duty:
370 * - prevent I/O (from us) so calling spi_setup() is safe;
371 * - prevent concurrent SPI_IOC_WR_* from morphing
372 * data fields while SPI_IOC_RD_* reads them;
373 * - SPI_IOC_MESSAGE needs the buffer locked "normally".
375 mutex_lock(&spidev->buf_lock);
379 case SPI_IOC_RD_MODE:
380 retval = put_user(spi->mode & SPI_MODE_MASK,
383 case SPI_IOC_RD_MODE32:
384 retval = put_user(spi->mode & SPI_MODE_MASK,
385 (__u32 __user *)arg);
387 case SPI_IOC_RD_LSB_FIRST:
388 retval = put_user((spi->mode & SPI_LSB_FIRST) ? 1 : 0,
391 case SPI_IOC_RD_BITS_PER_WORD:
392 retval = put_user(spi->bits_per_word, (__u8 __user *)arg);
394 case SPI_IOC_RD_MAX_SPEED_HZ:
395 retval = put_user(spidev->speed_hz, (__u32 __user *)arg);
399 case SPI_IOC_WR_MODE:
400 case SPI_IOC_WR_MODE32:
401 if (cmd == SPI_IOC_WR_MODE)
402 retval = get_user(tmp, (u8 __user *)arg);
404 retval = get_user(tmp, (u32 __user *)arg);
406 u32 save = spi->mode;
408 if (tmp & ~SPI_MODE_MASK) {
413 tmp |= spi->mode & ~SPI_MODE_MASK;
414 spi->mode = (u16)tmp;
415 retval = spi_setup(spi);
419 dev_dbg(&spi->dev, "spi mode %x\n", tmp);
422 case SPI_IOC_WR_LSB_FIRST:
423 retval = get_user(tmp, (__u8 __user *)arg);
425 u32 save = spi->mode;
428 spi->mode |= SPI_LSB_FIRST;
430 spi->mode &= ~SPI_LSB_FIRST;
431 retval = spi_setup(spi);
435 dev_dbg(&spi->dev, "%csb first\n",
439 case SPI_IOC_WR_BITS_PER_WORD:
440 retval = get_user(tmp, (__u8 __user *)arg);
442 u8 save = spi->bits_per_word;
444 spi->bits_per_word = tmp;
445 retval = spi_setup(spi);
447 spi->bits_per_word = save;
449 dev_dbg(&spi->dev, "%d bits per word\n", tmp);
452 case SPI_IOC_WR_MAX_SPEED_HZ:
453 retval = get_user(tmp, (__u32 __user *)arg);
455 u32 save = spi->max_speed_hz;
457 spi->max_speed_hz = tmp;
458 retval = spi_setup(spi);
460 spidev->speed_hz = tmp;
462 dev_dbg(&spi->dev, "%d Hz (max)\n", tmp);
463 spi->max_speed_hz = save;
468 /* segmented and/or full-duplex I/O request */
469 /* Check message and copy into scratch area */
470 ioc = spidev_get_ioc_message(cmd,
471 (struct spi_ioc_transfer __user *)arg, &n_ioc);
473 retval = PTR_ERR(ioc);
477 break; /* n_ioc is also 0 */
479 /* translate to spi_message, execute */
480 retval = spidev_message(spidev, ioc, n_ioc);
485 mutex_unlock(&spidev->buf_lock);
492 spidev_compat_ioc_message(struct file *filp, unsigned int cmd,
495 struct spi_ioc_transfer __user *u_ioc;
497 struct spidev_data *spidev;
498 struct spi_device *spi;
500 struct spi_ioc_transfer *ioc;
502 u_ioc = (struct spi_ioc_transfer __user *) compat_ptr(arg);
504 /* guard against device removal before, or while,
505 * we issue this ioctl.
507 spidev = filp->private_data;
508 spin_lock_irq(&spidev->spi_lock);
509 spi = spi_dev_get(spidev->spi);
510 spin_unlock_irq(&spidev->spi_lock);
515 /* SPI_IOC_MESSAGE needs the buffer locked "normally" */
516 mutex_lock(&spidev->buf_lock);
518 /* Check message and copy into scratch area */
519 ioc = spidev_get_ioc_message(cmd, u_ioc, &n_ioc);
521 retval = PTR_ERR(ioc);
525 goto done; /* n_ioc is also 0 */
527 /* Convert buffer pointers */
528 for (n = 0; n < n_ioc; n++) {
529 ioc[n].rx_buf = (uintptr_t) compat_ptr(ioc[n].rx_buf);
530 ioc[n].tx_buf = (uintptr_t) compat_ptr(ioc[n].tx_buf);
533 /* translate to spi_message, execute */
534 retval = spidev_message(spidev, ioc, n_ioc);
538 mutex_unlock(&spidev->buf_lock);
544 spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
546 if (_IOC_TYPE(cmd) == SPI_IOC_MAGIC
547 && _IOC_NR(cmd) == _IOC_NR(SPI_IOC_MESSAGE(0))
548 && _IOC_DIR(cmd) == _IOC_WRITE)
549 return spidev_compat_ioc_message(filp, cmd, arg);
551 return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
554 #define spidev_compat_ioctl NULL
555 #endif /* CONFIG_COMPAT */
557 static int spidev_open(struct inode *inode, struct file *filp)
559 struct spidev_data *spidev;
562 mutex_lock(&device_list_lock);
564 list_for_each_entry(spidev, &device_list, device_entry) {
565 if (spidev->devt == inode->i_rdev) {
572 pr_debug("spidev: nothing for minor %d\n", iminor(inode));
576 if (!spidev->tx_buffer) {
577 spidev->tx_buffer = kmalloc(bufsiz, GFP_KERNEL);
578 if (!spidev->tx_buffer) {
579 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
585 if (!spidev->rx_buffer) {
586 spidev->rx_buffer = kmalloc(bufsiz, GFP_KERNEL);
587 if (!spidev->rx_buffer) {
588 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
590 goto err_alloc_rx_buf;
595 filp->private_data = spidev;
596 stream_open(inode, filp);
598 mutex_unlock(&device_list_lock);
602 kfree(spidev->tx_buffer);
603 spidev->tx_buffer = NULL;
605 mutex_unlock(&device_list_lock);
609 static int spidev_release(struct inode *inode, struct file *filp)
611 struct spidev_data *spidev;
613 mutex_lock(&device_list_lock);
614 spidev = filp->private_data;
615 filp->private_data = NULL;
619 if (!spidev->users) {
622 kfree(spidev->tx_buffer);
623 spidev->tx_buffer = NULL;
625 kfree(spidev->rx_buffer);
626 spidev->rx_buffer = NULL;
628 spin_lock_irq(&spidev->spi_lock);
630 spidev->speed_hz = spidev->spi->max_speed_hz;
632 /* ... after we unbound from the underlying device? */
633 dofree = (spidev->spi == NULL);
634 spin_unlock_irq(&spidev->spi_lock);
639 mutex_unlock(&device_list_lock);
644 static const struct file_operations spidev_fops = {
645 .owner = THIS_MODULE,
646 /* REVISIT switch to aio primitives, so that userspace
647 * gets more complete API coverage. It'll simplify things
648 * too, except for the locking.
650 .write = spidev_write,
652 .unlocked_ioctl = spidev_ioctl,
653 .compat_ioctl = spidev_compat_ioctl,
655 .release = spidev_release,
659 /*-------------------------------------------------------------------------*/
661 /* The main reason to have this class is to make mdev/udev create the
662 * /dev/spidevB.C character device nodes exposing our userspace API.
663 * It also simplifies memory management.
666 static struct class *spidev_class;
669 static const struct of_device_id spidev_dt_ids[] = {
670 { .compatible = "rohm,dh2228fv" },
671 { .compatible = "lineartechnology,ltc2488" },
672 { .compatible = "ge,achc" },
673 { .compatible = "semtech,sx1301" },
674 { .compatible = "lwn,bk4" },
677 MODULE_DEVICE_TABLE(of, spidev_dt_ids);
682 /* Dummy SPI devices not to be used in production systems */
683 #define SPIDEV_ACPI_DUMMY 1
685 static const struct acpi_device_id spidev_acpi_ids[] = {
687 * The ACPI SPT000* devices are only meant for development and
688 * testing. Systems used in production should have a proper ACPI
689 * description of the connected peripheral and they should also use
690 * a proper driver instead of poking directly to the SPI bus.
692 { "SPT0001", SPIDEV_ACPI_DUMMY },
693 { "SPT0002", SPIDEV_ACPI_DUMMY },
694 { "SPT0003", SPIDEV_ACPI_DUMMY },
697 MODULE_DEVICE_TABLE(acpi, spidev_acpi_ids);
699 static void spidev_probe_acpi(struct spi_device *spi)
701 const struct acpi_device_id *id;
703 if (!has_acpi_companion(&spi->dev))
706 id = acpi_match_device(spidev_acpi_ids, &spi->dev);
710 if (id->driver_data == SPIDEV_ACPI_DUMMY)
711 dev_warn(&spi->dev, "do not use this driver in production systems!\n");
714 static inline void spidev_probe_acpi(struct spi_device *spi) {}
717 /*-------------------------------------------------------------------------*/
719 static int spidev_probe(struct spi_device *spi)
721 struct spidev_data *spidev;
726 * spidev should never be referenced in DT without a specific
727 * compatible string, it is a Linux implementation thing
728 * rather than a description of the hardware.
730 WARN(spi->dev.of_node &&
731 of_device_is_compatible(spi->dev.of_node, "spidev"),
732 "%pOF: buggy DT: spidev listed directly in DT\n", spi->dev.of_node);
734 spidev_probe_acpi(spi);
736 /* Allocate driver data */
737 spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);
741 /* Initialize the driver data */
743 spin_lock_init(&spidev->spi_lock);
744 mutex_init(&spidev->buf_lock);
746 INIT_LIST_HEAD(&spidev->device_entry);
748 /* If we can allocate a minor number, hook up this device.
749 * Reusing minors is fine so long as udev or mdev is working.
751 mutex_lock(&device_list_lock);
752 minor = find_first_zero_bit(minors, N_SPI_MINORS);
753 if (minor < N_SPI_MINORS) {
756 spidev->devt = MKDEV(SPIDEV_MAJOR, minor);
757 dev = device_create(spidev_class, &spi->dev, spidev->devt,
758 spidev, "spidev%d.%d",
759 spi->master->bus_num, spi->chip_select);
760 status = PTR_ERR_OR_ZERO(dev);
762 dev_dbg(&spi->dev, "no minor number available!\n");
766 set_bit(minor, minors);
767 list_add(&spidev->device_entry, &device_list);
769 mutex_unlock(&device_list_lock);
771 spidev->speed_hz = spi->max_speed_hz;
774 spi_set_drvdata(spi, spidev);
781 static int spidev_remove(struct spi_device *spi)
783 struct spidev_data *spidev = spi_get_drvdata(spi);
785 /* make sure ops on existing fds can abort cleanly */
786 spin_lock_irq(&spidev->spi_lock);
788 spin_unlock_irq(&spidev->spi_lock);
790 /* prevent new opens */
791 mutex_lock(&device_list_lock);
792 list_del(&spidev->device_entry);
793 device_destroy(spidev_class, spidev->devt);
794 clear_bit(MINOR(spidev->devt), minors);
795 if (spidev->users == 0)
797 mutex_unlock(&device_list_lock);
802 static struct spi_driver spidev_spi_driver = {
805 .of_match_table = of_match_ptr(spidev_dt_ids),
806 .acpi_match_table = ACPI_PTR(spidev_acpi_ids),
808 .probe = spidev_probe,
809 .remove = spidev_remove,
811 /* NOTE: suspend/resume methods are not necessary here.
812 * We don't do anything except pass the requests to/from
813 * the underlying controller. The refrigerator handles
814 * most issues; the controller driver handles the rest.
818 /*-------------------------------------------------------------------------*/
820 static int __init spidev_init(void)
824 /* Claim our 256 reserved device numbers. Then register a class
825 * that will key udev/mdev to add/remove /dev nodes. Last, register
826 * the driver which manages those device numbers.
828 BUILD_BUG_ON(N_SPI_MINORS > 256);
829 status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);
833 spidev_class = class_create(THIS_MODULE, "spidev");
834 if (IS_ERR(spidev_class)) {
835 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
836 return PTR_ERR(spidev_class);
839 status = spi_register_driver(&spidev_spi_driver);
841 class_destroy(spidev_class);
842 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
846 module_init(spidev_init);
848 static void __exit spidev_exit(void)
850 spi_unregister_driver(&spidev_spi_driver);
851 class_destroy(spidev_class);
852 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
854 module_exit(spidev_exit);
856 MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>");
857 MODULE_DESCRIPTION("User mode SPI device interface");
858 MODULE_LICENSE("GPL");
859 MODULE_ALIAS("spi:spidev");