1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * Simple synchronous userspace interface to SPI devices
5 * Copyright (C) 2006 SWAPP
6 * Andrea Paterniani <a.paterniani@swapp-eng.it>
7 * Copyright (C) 2007 David Brownell (simplification, cleanup)
10 #include <linux/init.h>
11 #include <linux/module.h>
12 #include <linux/ioctl.h>
14 #include <linux/device.h>
15 #include <linux/err.h>
16 #include <linux/list.h>
17 #include <linux/errno.h>
18 #include <linux/mutex.h>
19 #include <linux/slab.h>
20 #include <linux/compat.h>
22 #include <linux/of_device.h>
23 #include <linux/acpi.h>
25 #include <linux/spi/spi.h>
26 #include <linux/spi/spidev.h>
28 #include <linux/uaccess.h>
32 * This supports access to SPI devices using normal userspace I/O calls.
33 * Note that while traditional UNIX/POSIX I/O semantics are half duplex,
34 * and often mask message boundaries, full SPI support requires full duplex
35 * transfers. There are several kinds of internal message boundaries to
36 * handle chipselect management and other protocol options.
38 * SPI has a character major number assigned. We allocate minor numbers
39 * dynamically using a bitmask. You must use hotplug tools, such as udev
40 * (or mdev with busybox) to create and destroy the /dev/spidevB.C device
41 * nodes, since there is no fixed association of minor numbers with any
42 * particular SPI bus or device.
44 #define SPIDEV_MAJOR 153 /* assigned */
45 #define N_SPI_MINORS 32 /* ... up to 256 */
47 static DECLARE_BITMAP(minors, N_SPI_MINORS);
50 /* Bit masks for spi_device.mode management. Note that incorrect
51 * settings for some settings can cause *lots* of trouble for other
52 * devices on a shared bus:
54 * - CS_HIGH ... this device will be active when it shouldn't be
55 * - 3WIRE ... when active, it won't behave as it should
56 * - NO_CS ... there will be no explicit message boundaries; this
57 * is completely incompatible with the shared bus model
58 * - READY ... transfers may proceed when they shouldn't.
60 * REVISIT should changing those flags be privileged?
62 #define SPI_MODE_MASK (SPI_CPHA | SPI_CPOL | SPI_CS_HIGH \
63 | SPI_LSB_FIRST | SPI_3WIRE | SPI_LOOP \
64 | SPI_NO_CS | SPI_READY | SPI_TX_DUAL \
65 | SPI_TX_QUAD | SPI_RX_DUAL | SPI_RX_QUAD)
70 struct spi_device *spi;
71 struct list_head device_entry;
73 /* TX/RX buffers are NULL unless this device is open (users > 0) */
74 struct mutex buf_lock;
81 static LIST_HEAD(device_list);
82 static DEFINE_MUTEX(device_list_lock);
84 static unsigned bufsiz = 4096;
85 module_param(bufsiz, uint, S_IRUGO);
86 MODULE_PARM_DESC(bufsiz, "data bytes in biggest supported SPI message");
88 /*-------------------------------------------------------------------------*/
91 spidev_sync(struct spidev_data *spidev, struct spi_message *message)
94 struct spi_device *spi;
96 spin_lock_irq(&spidev->spi_lock);
98 spin_unlock_irq(&spidev->spi_lock);
103 status = spi_sync(spi, message);
106 status = message->actual_length;
111 static inline ssize_t
112 spidev_sync_write(struct spidev_data *spidev, size_t len)
114 struct spi_transfer t = {
115 .tx_buf = spidev->tx_buffer,
117 .speed_hz = spidev->speed_hz,
119 struct spi_message m;
121 spi_message_init(&m);
122 spi_message_add_tail(&t, &m);
123 return spidev_sync(spidev, &m);
126 static inline ssize_t
127 spidev_sync_read(struct spidev_data *spidev, size_t len)
129 struct spi_transfer t = {
130 .rx_buf = spidev->rx_buffer,
132 .speed_hz = spidev->speed_hz,
134 struct spi_message m;
136 spi_message_init(&m);
137 spi_message_add_tail(&t, &m);
138 return spidev_sync(spidev, &m);
141 /*-------------------------------------------------------------------------*/
143 /* Read-only message with current device setup */
145 spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
147 struct spidev_data *spidev;
150 /* chipselect only toggles at start or end of operation */
154 spidev = filp->private_data;
156 mutex_lock(&spidev->buf_lock);
157 status = spidev_sync_read(spidev, count);
159 unsigned long missing;
161 missing = copy_to_user(buf, spidev->rx_buffer, status);
162 if (missing == status)
165 status = status - missing;
167 mutex_unlock(&spidev->buf_lock);
172 /* Write-only message with current device setup */
174 spidev_write(struct file *filp, const char __user *buf,
175 size_t count, loff_t *f_pos)
177 struct spidev_data *spidev;
179 unsigned long missing;
181 /* chipselect only toggles at start or end of operation */
185 spidev = filp->private_data;
187 mutex_lock(&spidev->buf_lock);
188 missing = copy_from_user(spidev->tx_buffer, buf, count);
190 status = spidev_sync_write(spidev, count);
193 mutex_unlock(&spidev->buf_lock);
198 static int spidev_message(struct spidev_data *spidev,
199 struct spi_ioc_transfer *u_xfers, unsigned n_xfers)
201 struct spi_message msg;
202 struct spi_transfer *k_xfers;
203 struct spi_transfer *k_tmp;
204 struct spi_ioc_transfer *u_tmp;
205 unsigned n, total, tx_total, rx_total;
207 int status = -EFAULT;
209 spi_message_init(&msg);
210 k_xfers = kcalloc(n_xfers, sizeof(*k_tmp), GFP_KERNEL);
214 /* Construct spi_message, copying any tx data to bounce buffer.
215 * We walk the array of user-provided transfers, using each one
216 * to initialize a kernel version of the same transfer.
218 tx_buf = spidev->tx_buffer;
219 rx_buf = spidev->rx_buffer;
223 for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers;
225 n--, k_tmp++, u_tmp++) {
226 k_tmp->len = u_tmp->len;
229 /* Since the function returns the total length of transfers
230 * on success, restrict the total to positive int values to
231 * avoid the return value looking like an error. Also check
232 * each transfer length to avoid arithmetic overflow.
234 if (total > INT_MAX || k_tmp->len > INT_MAX) {
240 /* this transfer needs space in RX bounce buffer */
241 rx_total += k_tmp->len;
242 if (rx_total > bufsiz) {
246 k_tmp->rx_buf = rx_buf;
247 rx_buf += k_tmp->len;
250 /* this transfer needs space in TX bounce buffer */
251 tx_total += k_tmp->len;
252 if (tx_total > bufsiz) {
256 k_tmp->tx_buf = tx_buf;
257 if (copy_from_user(tx_buf, (const u8 __user *)
258 (uintptr_t) u_tmp->tx_buf,
261 tx_buf += k_tmp->len;
264 k_tmp->cs_change = !!u_tmp->cs_change;
265 k_tmp->tx_nbits = u_tmp->tx_nbits;
266 k_tmp->rx_nbits = u_tmp->rx_nbits;
267 k_tmp->bits_per_word = u_tmp->bits_per_word;
268 k_tmp->delay.value = u_tmp->delay_usecs;
269 k_tmp->delay.unit = SPI_DELAY_UNIT_USECS;
270 k_tmp->speed_hz = u_tmp->speed_hz;
271 k_tmp->word_delay.value = u_tmp->word_delay_usecs;
272 k_tmp->word_delay.unit = SPI_DELAY_UNIT_USECS;
273 if (!k_tmp->speed_hz)
274 k_tmp->speed_hz = spidev->speed_hz;
276 dev_dbg(&spidev->spi->dev,
277 " xfer len %u %s%s%s%dbits %u usec %u usec %uHz\n",
279 u_tmp->rx_buf ? "rx " : "",
280 u_tmp->tx_buf ? "tx " : "",
281 u_tmp->cs_change ? "cs " : "",
282 u_tmp->bits_per_word ? : spidev->spi->bits_per_word,
284 u_tmp->word_delay_usecs,
285 u_tmp->speed_hz ? : spidev->spi->max_speed_hz);
287 spi_message_add_tail(k_tmp, &msg);
290 status = spidev_sync(spidev, &msg);
294 /* copy any rx data out of bounce buffer */
295 rx_buf = spidev->rx_buffer;
296 for (n = n_xfers, u_tmp = u_xfers; n; n--, u_tmp++) {
298 if (copy_to_user((u8 __user *)
299 (uintptr_t) u_tmp->rx_buf, rx_buf,
304 rx_buf += u_tmp->len;
314 static struct spi_ioc_transfer *
315 spidev_get_ioc_message(unsigned int cmd, struct spi_ioc_transfer __user *u_ioc,
320 /* Check type, command number and direction */
321 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC
322 || _IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0))
323 || _IOC_DIR(cmd) != _IOC_WRITE)
324 return ERR_PTR(-ENOTTY);
326 tmp = _IOC_SIZE(cmd);
327 if ((tmp % sizeof(struct spi_ioc_transfer)) != 0)
328 return ERR_PTR(-EINVAL);
329 *n_ioc = tmp / sizeof(struct spi_ioc_transfer);
333 /* copy into scratch area */
334 return memdup_user(u_ioc, tmp);
338 spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
341 struct spidev_data *spidev;
342 struct spi_device *spi;
345 struct spi_ioc_transfer *ioc;
347 /* Check type and command number */
348 if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC)
351 /* guard against device removal before, or while,
352 * we issue this ioctl.
354 spidev = filp->private_data;
355 spin_lock_irq(&spidev->spi_lock);
356 spi = spi_dev_get(spidev->spi);
357 spin_unlock_irq(&spidev->spi_lock);
362 /* use the buffer lock here for triple duty:
363 * - prevent I/O (from us) so calling spi_setup() is safe;
364 * - prevent concurrent SPI_IOC_WR_* from morphing
365 * data fields while SPI_IOC_RD_* reads them;
366 * - SPI_IOC_MESSAGE needs the buffer locked "normally".
368 mutex_lock(&spidev->buf_lock);
372 case SPI_IOC_RD_MODE:
373 retval = put_user(spi->mode & SPI_MODE_MASK,
376 case SPI_IOC_RD_MODE32:
377 retval = put_user(spi->mode & SPI_MODE_MASK,
378 (__u32 __user *)arg);
380 case SPI_IOC_RD_LSB_FIRST:
381 retval = put_user((spi->mode & SPI_LSB_FIRST) ? 1 : 0,
384 case SPI_IOC_RD_BITS_PER_WORD:
385 retval = put_user(spi->bits_per_word, (__u8 __user *)arg);
387 case SPI_IOC_RD_MAX_SPEED_HZ:
388 retval = put_user(spidev->speed_hz, (__u32 __user *)arg);
392 case SPI_IOC_WR_MODE:
393 case SPI_IOC_WR_MODE32:
394 if (cmd == SPI_IOC_WR_MODE)
395 retval = get_user(tmp, (u8 __user *)arg);
397 retval = get_user(tmp, (u32 __user *)arg);
399 struct spi_controller *ctlr = spi->controller;
400 u32 save = spi->mode;
402 if (tmp & ~SPI_MODE_MASK) {
407 if (ctlr->use_gpio_descriptors && ctlr->cs_gpiods &&
408 ctlr->cs_gpiods[spi->chip_select])
411 tmp |= spi->mode & ~SPI_MODE_MASK;
412 spi->mode = (u16)tmp;
413 retval = spi_setup(spi);
417 dev_dbg(&spi->dev, "spi mode %x\n", tmp);
420 case SPI_IOC_WR_LSB_FIRST:
421 retval = get_user(tmp, (__u8 __user *)arg);
423 u32 save = spi->mode;
426 spi->mode |= SPI_LSB_FIRST;
428 spi->mode &= ~SPI_LSB_FIRST;
429 retval = spi_setup(spi);
433 dev_dbg(&spi->dev, "%csb first\n",
437 case SPI_IOC_WR_BITS_PER_WORD:
438 retval = get_user(tmp, (__u8 __user *)arg);
440 u8 save = spi->bits_per_word;
442 spi->bits_per_word = tmp;
443 retval = spi_setup(spi);
445 spi->bits_per_word = save;
447 dev_dbg(&spi->dev, "%d bits per word\n", tmp);
450 case SPI_IOC_WR_MAX_SPEED_HZ:
451 retval = get_user(tmp, (__u32 __user *)arg);
453 u32 save = spi->max_speed_hz;
455 spi->max_speed_hz = tmp;
456 retval = spi_setup(spi);
458 spidev->speed_hz = tmp;
460 dev_dbg(&spi->dev, "%d Hz (max)\n", tmp);
461 spi->max_speed_hz = save;
466 /* segmented and/or full-duplex I/O request */
467 /* Check message and copy into scratch area */
468 ioc = spidev_get_ioc_message(cmd,
469 (struct spi_ioc_transfer __user *)arg, &n_ioc);
471 retval = PTR_ERR(ioc);
475 break; /* n_ioc is also 0 */
477 /* translate to spi_message, execute */
478 retval = spidev_message(spidev, ioc, n_ioc);
483 mutex_unlock(&spidev->buf_lock);
490 spidev_compat_ioc_message(struct file *filp, unsigned int cmd,
493 struct spi_ioc_transfer __user *u_ioc;
495 struct spidev_data *spidev;
496 struct spi_device *spi;
498 struct spi_ioc_transfer *ioc;
500 u_ioc = (struct spi_ioc_transfer __user *) compat_ptr(arg);
502 /* guard against device removal before, or while,
503 * we issue this ioctl.
505 spidev = filp->private_data;
506 spin_lock_irq(&spidev->spi_lock);
507 spi = spi_dev_get(spidev->spi);
508 spin_unlock_irq(&spidev->spi_lock);
513 /* SPI_IOC_MESSAGE needs the buffer locked "normally" */
514 mutex_lock(&spidev->buf_lock);
516 /* Check message and copy into scratch area */
517 ioc = spidev_get_ioc_message(cmd, u_ioc, &n_ioc);
519 retval = PTR_ERR(ioc);
523 goto done; /* n_ioc is also 0 */
525 /* Convert buffer pointers */
526 for (n = 0; n < n_ioc; n++) {
527 ioc[n].rx_buf = (uintptr_t) compat_ptr(ioc[n].rx_buf);
528 ioc[n].tx_buf = (uintptr_t) compat_ptr(ioc[n].tx_buf);
531 /* translate to spi_message, execute */
532 retval = spidev_message(spidev, ioc, n_ioc);
536 mutex_unlock(&spidev->buf_lock);
542 spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
544 if (_IOC_TYPE(cmd) == SPI_IOC_MAGIC
545 && _IOC_NR(cmd) == _IOC_NR(SPI_IOC_MESSAGE(0))
546 && _IOC_DIR(cmd) == _IOC_WRITE)
547 return spidev_compat_ioc_message(filp, cmd, arg);
549 return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
552 #define spidev_compat_ioctl NULL
553 #endif /* CONFIG_COMPAT */
555 static int spidev_open(struct inode *inode, struct file *filp)
557 struct spidev_data *spidev;
560 mutex_lock(&device_list_lock);
562 list_for_each_entry(spidev, &device_list, device_entry) {
563 if (spidev->devt == inode->i_rdev) {
570 pr_debug("spidev: nothing for minor %d\n", iminor(inode));
574 if (!spidev->tx_buffer) {
575 spidev->tx_buffer = kmalloc(bufsiz, GFP_KERNEL);
576 if (!spidev->tx_buffer) {
577 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
583 if (!spidev->rx_buffer) {
584 spidev->rx_buffer = kmalloc(bufsiz, GFP_KERNEL);
585 if (!spidev->rx_buffer) {
586 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
588 goto err_alloc_rx_buf;
593 filp->private_data = spidev;
594 stream_open(inode, filp);
596 mutex_unlock(&device_list_lock);
600 kfree(spidev->tx_buffer);
601 spidev->tx_buffer = NULL;
603 mutex_unlock(&device_list_lock);
607 static int spidev_release(struct inode *inode, struct file *filp)
609 struct spidev_data *spidev;
611 mutex_lock(&device_list_lock);
612 spidev = filp->private_data;
613 filp->private_data = NULL;
617 if (!spidev->users) {
620 kfree(spidev->tx_buffer);
621 spidev->tx_buffer = NULL;
623 kfree(spidev->rx_buffer);
624 spidev->rx_buffer = NULL;
626 spin_lock_irq(&spidev->spi_lock);
628 spidev->speed_hz = spidev->spi->max_speed_hz;
630 /* ... after we unbound from the underlying device? */
631 dofree = (spidev->spi == NULL);
632 spin_unlock_irq(&spidev->spi_lock);
637 #ifdef CONFIG_SPI_SLAVE
638 spi_slave_abort(spidev->spi);
640 mutex_unlock(&device_list_lock);
645 static const struct file_operations spidev_fops = {
646 .owner = THIS_MODULE,
647 /* REVISIT switch to aio primitives, so that userspace
648 * gets more complete API coverage. It'll simplify things
649 * too, except for the locking.
651 .write = spidev_write,
653 .unlocked_ioctl = spidev_ioctl,
654 .compat_ioctl = spidev_compat_ioctl,
656 .release = spidev_release,
660 /*-------------------------------------------------------------------------*/
662 /* The main reason to have this class is to make mdev/udev create the
663 * /dev/spidevB.C character device nodes exposing our userspace API.
664 * It also simplifies memory management.
667 static struct class *spidev_class;
670 static const struct of_device_id spidev_dt_ids[] = {
671 { .compatible = "rohm,dh2228fv" },
672 { .compatible = "lineartechnology,ltc2488" },
673 { .compatible = "ge,achc" },
674 { .compatible = "semtech,sx1301" },
675 { .compatible = "lwn,bk4" },
676 { .compatible = "dh,dhcom-board" },
677 { .compatible = "menlo,m53cpld" },
680 MODULE_DEVICE_TABLE(of, spidev_dt_ids);
685 /* Dummy SPI devices not to be used in production systems */
686 #define SPIDEV_ACPI_DUMMY 1
688 static const struct acpi_device_id spidev_acpi_ids[] = {
690 * The ACPI SPT000* devices are only meant for development and
691 * testing. Systems used in production should have a proper ACPI
692 * description of the connected peripheral and they should also use
693 * a proper driver instead of poking directly to the SPI bus.
695 { "SPT0001", SPIDEV_ACPI_DUMMY },
696 { "SPT0002", SPIDEV_ACPI_DUMMY },
697 { "SPT0003", SPIDEV_ACPI_DUMMY },
700 MODULE_DEVICE_TABLE(acpi, spidev_acpi_ids);
702 static void spidev_probe_acpi(struct spi_device *spi)
704 const struct acpi_device_id *id;
706 if (!has_acpi_companion(&spi->dev))
709 id = acpi_match_device(spidev_acpi_ids, &spi->dev);
713 if (id->driver_data == SPIDEV_ACPI_DUMMY)
714 dev_warn(&spi->dev, "do not use this driver in production systems!\n");
717 static inline void spidev_probe_acpi(struct spi_device *spi) {}
720 /*-------------------------------------------------------------------------*/
722 static int spidev_probe(struct spi_device *spi)
724 struct spidev_data *spidev;
729 * spidev should never be referenced in DT without a specific
730 * compatible string, it is a Linux implementation thing
731 * rather than a description of the hardware.
733 WARN(spi->dev.of_node &&
734 of_device_is_compatible(spi->dev.of_node, "spidev"),
735 "%pOF: buggy DT: spidev listed directly in DT\n", spi->dev.of_node);
737 spidev_probe_acpi(spi);
739 /* Allocate driver data */
740 spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);
744 /* Initialize the driver data */
746 spin_lock_init(&spidev->spi_lock);
747 mutex_init(&spidev->buf_lock);
749 INIT_LIST_HEAD(&spidev->device_entry);
751 /* If we can allocate a minor number, hook up this device.
752 * Reusing minors is fine so long as udev or mdev is working.
754 mutex_lock(&device_list_lock);
755 minor = find_first_zero_bit(minors, N_SPI_MINORS);
756 if (minor < N_SPI_MINORS) {
759 spidev->devt = MKDEV(SPIDEV_MAJOR, minor);
760 dev = device_create(spidev_class, &spi->dev, spidev->devt,
761 spidev, "spidev%d.%d",
762 spi->master->bus_num, spi->chip_select);
763 status = PTR_ERR_OR_ZERO(dev);
765 dev_dbg(&spi->dev, "no minor number available!\n");
769 set_bit(minor, minors);
770 list_add(&spidev->device_entry, &device_list);
772 mutex_unlock(&device_list_lock);
774 spidev->speed_hz = spi->max_speed_hz;
777 spi_set_drvdata(spi, spidev);
784 static int spidev_remove(struct spi_device *spi)
786 struct spidev_data *spidev = spi_get_drvdata(spi);
788 /* make sure ops on existing fds can abort cleanly */
789 spin_lock_irq(&spidev->spi_lock);
791 spin_unlock_irq(&spidev->spi_lock);
793 /* prevent new opens */
794 mutex_lock(&device_list_lock);
795 list_del(&spidev->device_entry);
796 device_destroy(spidev_class, spidev->devt);
797 clear_bit(MINOR(spidev->devt), minors);
798 if (spidev->users == 0)
800 mutex_unlock(&device_list_lock);
805 static struct spi_driver spidev_spi_driver = {
808 .of_match_table = of_match_ptr(spidev_dt_ids),
809 .acpi_match_table = ACPI_PTR(spidev_acpi_ids),
811 .probe = spidev_probe,
812 .remove = spidev_remove,
814 /* NOTE: suspend/resume methods are not necessary here.
815 * We don't do anything except pass the requests to/from
816 * the underlying controller. The refrigerator handles
817 * most issues; the controller driver handles the rest.
821 /*-------------------------------------------------------------------------*/
823 static int __init spidev_init(void)
827 /* Claim our 256 reserved device numbers. Then register a class
828 * that will key udev/mdev to add/remove /dev nodes. Last, register
829 * the driver which manages those device numbers.
831 BUILD_BUG_ON(N_SPI_MINORS > 256);
832 status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);
836 spidev_class = class_create(THIS_MODULE, "spidev");
837 if (IS_ERR(spidev_class)) {
838 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
839 return PTR_ERR(spidev_class);
842 status = spi_register_driver(&spidev_spi_driver);
844 class_destroy(spidev_class);
845 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
849 module_init(spidev_init);
851 static void __exit spidev_exit(void)
853 spi_unregister_driver(&spidev_spi_driver);
854 class_destroy(spidev_class);
855 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
857 module_exit(spidev_exit);
859 MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>");
860 MODULE_DESCRIPTION("User mode SPI device interface");
861 MODULE_LICENSE("GPL");
862 MODULE_ALIAS("spi:spidev");