// SPDX-License-Identifier: GPL-2.0-or-later /* * Simple synchronous userspace interface to SPI devices * * Copyright (C) 2006 SWAPP * Andrea Paterniani * Copyright (C) 2007 David Brownell (simplification, cleanup) */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * This supports access to SPI devices using normal userspace I/O calls. * Note that while traditional UNIX/POSIX I/O semantics are half duplex, * and often mask message boundaries, full SPI support requires full duplex * transfers. There are several kinds of internal message boundaries to * handle chipselect management and other protocol options. * * SPI has a character major number assigned. We allocate minor numbers * dynamically using a bitmask. You must use hotplug tools, such as udev * (or mdev with busybox) to create and destroy the /dev/spidevB.C device * nodes, since there is no fixed association of minor numbers with any * particular SPI bus or device. */ #define SPIDEV_MAJOR 153 /* assigned */ #define N_SPI_MINORS 32 /* ... up to 256 */ static DECLARE_BITMAP(minors, N_SPI_MINORS); /* Bit masks for spi_device.mode management. Note that incorrect * settings for some settings can cause *lots* of trouble for other * devices on a shared bus: * * - CS_HIGH ... this device will be active when it shouldn't be * - 3WIRE ... when active, it won't behave as it should * - NO_CS ... there will be no explicit message boundaries; this * is completely incompatible with the shared bus model * - READY ... transfers may proceed when they shouldn't. * * REVISIT should changing those flags be privileged? */ #define SPI_MODE_MASK (SPI_CPHA | SPI_CPOL | SPI_CS_HIGH \ | SPI_LSB_FIRST | SPI_3WIRE | SPI_LOOP \ | SPI_NO_CS | SPI_READY | SPI_TX_DUAL \ | SPI_TX_QUAD | SPI_RX_DUAL | SPI_RX_QUAD) struct spidev_data { dev_t devt; spinlock_t spi_lock; struct spi_device *spi; struct list_head device_entry; /* TX/RX buffers are NULL unless this device is open (users > 0) */ struct mutex buf_lock; unsigned users; u8 *tx_buffer; u8 *rx_buffer; u32 speed_hz; }; static LIST_HEAD(device_list); static DEFINE_MUTEX(device_list_lock); static unsigned bufsiz = 4096; module_param(bufsiz, uint, S_IRUGO); MODULE_PARM_DESC(bufsiz, "data bytes in biggest supported SPI message"); /*-------------------------------------------------------------------------*/ static ssize_t spidev_sync(struct spidev_data *spidev, struct spi_message *message) { int status; struct spi_device *spi; spin_lock_irq(&spidev->spi_lock); spi = spidev->spi; spin_unlock_irq(&spidev->spi_lock); if (spi == NULL) status = -ESHUTDOWN; else status = spi_sync(spi, message); if (status == 0) status = message->actual_length; return status; } static inline ssize_t spidev_sync_write(struct spidev_data *spidev, size_t len) { struct spi_transfer t = { .tx_buf = spidev->tx_buffer, .len = len, .speed_hz = spidev->speed_hz, }; struct spi_message m; spi_message_init(&m); spi_message_add_tail(&t, &m); return spidev_sync(spidev, &m); } static inline ssize_t spidev_sync_read(struct spidev_data *spidev, size_t len) { struct spi_transfer t = { .rx_buf = spidev->rx_buffer, .len = len, .speed_hz = spidev->speed_hz, }; struct spi_message m; spi_message_init(&m); spi_message_add_tail(&t, &m); return spidev_sync(spidev, &m); } /*-------------------------------------------------------------------------*/ /* Read-only message with current device setup */ static ssize_t spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos) { struct spidev_data *spidev; ssize_t status = 0; /* chipselect only toggles at start or end of operation */ if (count > bufsiz) return -EMSGSIZE; spidev = filp->private_data; mutex_lock(&spidev->buf_lock); status = spidev_sync_read(spidev, count); if (status > 0) { unsigned long missing; missing = copy_to_user(buf, spidev->rx_buffer, status); if (missing == status) status = -EFAULT; else status = status - missing; } mutex_unlock(&spidev->buf_lock); return status; } /* Write-only message with current device setup */ static ssize_t spidev_write(struct file *filp, const char __user *buf, size_t count, loff_t *f_pos) { struct spidev_data *spidev; ssize_t status = 0; unsigned long missing; /* chipselect only toggles at start or end of operation */ if (count > bufsiz) return -EMSGSIZE; spidev = filp->private_data; mutex_lock(&spidev->buf_lock); missing = copy_from_user(spidev->tx_buffer, buf, count); if (missing == 0) status = spidev_sync_write(spidev, count); else status = -EFAULT; mutex_unlock(&spidev->buf_lock); return status; } static int spidev_message(struct spidev_data *spidev, struct spi_ioc_transfer *u_xfers, unsigned n_xfers) { struct spi_message msg; struct spi_transfer *k_xfers; struct spi_transfer *k_tmp; struct spi_ioc_transfer *u_tmp; unsigned n, total, tx_total, rx_total; u8 *tx_buf, *rx_buf; int status = -EFAULT; spi_message_init(&msg); k_xfers = kcalloc(n_xfers, sizeof(*k_tmp), GFP_KERNEL); if (k_xfers == NULL) return -ENOMEM; /* Construct spi_message, copying any tx data to bounce buffer. * We walk the array of user-provided transfers, using each one * to initialize a kernel version of the same transfer. */ tx_buf = spidev->tx_buffer; rx_buf = spidev->rx_buffer; total = 0; tx_total = 0; rx_total = 0; for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers; n; n--, k_tmp++, u_tmp++) { k_tmp->len = u_tmp->len; total += k_tmp->len; /* Since the function returns the total length of transfers * on success, restrict the total to positive int values to * avoid the return value looking like an error. Also check * each transfer length to avoid arithmetic overflow. */ if (total > INT_MAX || k_tmp->len > INT_MAX) { status = -EMSGSIZE; goto done; } if (u_tmp->rx_buf) { /* this transfer needs space in RX bounce buffer */ rx_total += k_tmp->len; if (rx_total > bufsiz) { status = -EMSGSIZE; goto done; } k_tmp->rx_buf = rx_buf; rx_buf += k_tmp->len; } if (u_tmp->tx_buf) { /* this transfer needs space in TX bounce buffer */ tx_total += k_tmp->len; if (tx_total > bufsiz) { status = -EMSGSIZE; goto done; } k_tmp->tx_buf = tx_buf; if (copy_from_user(tx_buf, (const u8 __user *) (uintptr_t) u_tmp->tx_buf, u_tmp->len)) goto done; tx_buf += k_tmp->len; } k_tmp->cs_change = !!u_tmp->cs_change; k_tmp->tx_nbits = u_tmp->tx_nbits; k_tmp->rx_nbits = u_tmp->rx_nbits; k_tmp->bits_per_word = u_tmp->bits_per_word; k_tmp->delay_usecs = u_tmp->delay_usecs; k_tmp->speed_hz = u_tmp->speed_hz; k_tmp->word_delay_usecs = u_tmp->word_delay_usecs; if (!k_tmp->speed_hz) k_tmp->speed_hz = spidev->speed_hz; #ifdef VERBOSE dev_dbg(&spidev->spi->dev, " xfer len %u %s%s%s%dbits %u usec %u usec %uHz\n", u_tmp->len, u_tmp->rx_buf ? "rx " : "", u_tmp->tx_buf ? "tx " : "", u_tmp->cs_change ? "cs " : "", u_tmp->bits_per_word ? : spidev->spi->bits_per_word, u_tmp->delay_usecs, u_tmp->word_delay_usecs, u_tmp->speed_hz ? : spidev->spi->max_speed_hz); #endif spi_message_add_tail(k_tmp, &msg); } status = spidev_sync(spidev, &msg); if (status < 0) goto done; /* copy any rx data out of bounce buffer */ rx_buf = spidev->rx_buffer; for (n = n_xfers, u_tmp = u_xfers; n; n--, u_tmp++) { if (u_tmp->rx_buf) { if (copy_to_user((u8 __user *) (uintptr_t) u_tmp->rx_buf, rx_buf, u_tmp->len)) { status = -EFAULT; goto done; } rx_buf += u_tmp->len; } } status = total; done: kfree(k_xfers); return status; } static struct spi_ioc_transfer * spidev_get_ioc_message(unsigned int cmd, struct spi_ioc_transfer __user *u_ioc, unsigned *n_ioc) { u32 tmp; /* Check type, command number and direction */ if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC || _IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0)) || _IOC_DIR(cmd) != _IOC_WRITE) return ERR_PTR(-ENOTTY); tmp = _IOC_SIZE(cmd); if ((tmp % sizeof(struct spi_ioc_transfer)) != 0) return ERR_PTR(-EINVAL); *n_ioc = tmp / sizeof(struct spi_ioc_transfer); if (*n_ioc == 0) return NULL; /* copy into scratch area */ return memdup_user(u_ioc, tmp); } static long spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) { int retval = 0; struct spidev_data *spidev; struct spi_device *spi; u32 tmp; unsigned n_ioc; struct spi_ioc_transfer *ioc; /* Check type and command number */ if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC) return -ENOTTY; /* guard against device removal before, or while, * we issue this ioctl. */ spidev = filp->private_data; spin_lock_irq(&spidev->spi_lock); spi = spi_dev_get(spidev->spi); spin_unlock_irq(&spidev->spi_lock); if (spi == NULL) return -ESHUTDOWN; /* use the buffer lock here for triple duty: * - prevent I/O (from us) so calling spi_setup() is safe; * - prevent concurrent SPI_IOC_WR_* from morphing * data fields while SPI_IOC_RD_* reads them; * - SPI_IOC_MESSAGE needs the buffer locked "normally". */ mutex_lock(&spidev->buf_lock); switch (cmd) { /* read requests */ case SPI_IOC_RD_MODE: retval = put_user(spi->mode & SPI_MODE_MASK, (__u8 __user *)arg); break; case SPI_IOC_RD_MODE32: retval = put_user(spi->mode & SPI_MODE_MASK, (__u32 __user *)arg); break; case SPI_IOC_RD_LSB_FIRST: retval = put_user((spi->mode & SPI_LSB_FIRST) ? 1 : 0, (__u8 __user *)arg); break; case SPI_IOC_RD_BITS_PER_WORD: retval = put_user(spi->bits_per_word, (__u8 __user *)arg); break; case SPI_IOC_RD_MAX_SPEED_HZ: retval = put_user(spidev->speed_hz, (__u32 __user *)arg); break; /* write requests */ case SPI_IOC_WR_MODE: case SPI_IOC_WR_MODE32: if (cmd == SPI_IOC_WR_MODE) retval = get_user(tmp, (u8 __user *)arg); else retval = get_user(tmp, (u32 __user *)arg); if (retval == 0) { struct spi_controller *ctlr = spi->controller; u32 save = spi->mode; if (tmp & ~SPI_MODE_MASK) { retval = -EINVAL; break; } if (ctlr->use_gpio_descriptors && ctlr->cs_gpiods && ctlr->cs_gpiods[spi->chip_select]) tmp |= SPI_CS_HIGH; tmp |= spi->mode & ~SPI_MODE_MASK; spi->mode = (u16)tmp; retval = spi_setup(spi); if (retval < 0) spi->mode = save; else dev_dbg(&spi->dev, "spi mode %x\n", tmp); } break; case SPI_IOC_WR_LSB_FIRST: retval = get_user(tmp, (__u8 __user *)arg); if (retval == 0) { u32 save = spi->mode; if (tmp) spi->mode |= SPI_LSB_FIRST; else spi->mode &= ~SPI_LSB_FIRST; retval = spi_setup(spi); if (retval < 0) spi->mode = save; else dev_dbg(&spi->dev, "%csb first\n", tmp ? 'l' : 'm'); } break; case SPI_IOC_WR_BITS_PER_WORD: retval = get_user(tmp, (__u8 __user *)arg); if (retval == 0) { u8 save = spi->bits_per_word; spi->bits_per_word = tmp; retval = spi_setup(spi); if (retval < 0) spi->bits_per_word = save; else dev_dbg(&spi->dev, "%d bits per word\n", tmp); } break; case SPI_IOC_WR_MAX_SPEED_HZ: retval = get_user(tmp, (__u32 __user *)arg); if (retval == 0) { u32 save = spi->max_speed_hz; spi->max_speed_hz = tmp; retval = spi_setup(spi); if (retval >= 0) spidev->speed_hz = tmp; else dev_dbg(&spi->dev, "%d Hz (max)\n", tmp); spi->max_speed_hz = save; } break; default: /* segmented and/or full-duplex I/O request */ /* Check message and copy into scratch area */ ioc = spidev_get_ioc_message(cmd, (struct spi_ioc_transfer __user *)arg, &n_ioc); if (IS_ERR(ioc)) { retval = PTR_ERR(ioc); break; } if (!ioc) break; /* n_ioc is also 0 */ /* translate to spi_message, execute */ retval = spidev_message(spidev, ioc, n_ioc); kfree(ioc); break; } mutex_unlock(&spidev->buf_lock); spi_dev_put(spi); return retval; } #ifdef CONFIG_COMPAT static long spidev_compat_ioc_message(struct file *filp, unsigned int cmd, unsigned long arg) { struct spi_ioc_transfer __user *u_ioc; int retval = 0; struct spidev_data *spidev; struct spi_device *spi; unsigned n_ioc, n; struct spi_ioc_transfer *ioc; u_ioc = (struct spi_ioc_transfer __user *) compat_ptr(arg); /* guard against device removal before, or while, * we issue this ioctl. */ spidev = filp->private_data; spin_lock_irq(&spidev->spi_lock); spi = spi_dev_get(spidev->spi); spin_unlock_irq(&spidev->spi_lock); if (spi == NULL) return -ESHUTDOWN; /* SPI_IOC_MESSAGE needs the buffer locked "normally" */ mutex_lock(&spidev->buf_lock); /* Check message and copy into scratch area */ ioc = spidev_get_ioc_message(cmd, u_ioc, &n_ioc); if (IS_ERR(ioc)) { retval = PTR_ERR(ioc); goto done; } if (!ioc) goto done; /* n_ioc is also 0 */ /* Convert buffer pointers */ for (n = 0; n < n_ioc; n++) { ioc[n].rx_buf = (uintptr_t) compat_ptr(ioc[n].rx_buf); ioc[n].tx_buf = (uintptr_t) compat_ptr(ioc[n].tx_buf); } /* translate to spi_message, execute */ retval = spidev_message(spidev, ioc, n_ioc); kfree(ioc); done: mutex_unlock(&spidev->buf_lock); spi_dev_put(spi); return retval; } static long spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) { if (_IOC_TYPE(cmd) == SPI_IOC_MAGIC && _IOC_NR(cmd) == _IOC_NR(SPI_IOC_MESSAGE(0)) && _IOC_DIR(cmd) == _IOC_WRITE) return spidev_compat_ioc_message(filp, cmd, arg); return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg)); } #else #define spidev_compat_ioctl NULL #endif /* CONFIG_COMPAT */ static int spidev_open(struct inode *inode, struct file *filp) { struct spidev_data *spidev; int status = -ENXIO; mutex_lock(&device_list_lock); list_for_each_entry(spidev, &device_list, device_entry) { if (spidev->devt == inode->i_rdev) { status = 0; break; } } if (status) { pr_debug("spidev: nothing for minor %d\n", iminor(inode)); goto err_find_dev; } if (!spidev->tx_buffer) { spidev->tx_buffer = kmalloc(bufsiz, GFP_KERNEL); if (!spidev->tx_buffer) { dev_dbg(&spidev->spi->dev, "open/ENOMEM\n"); status = -ENOMEM; goto err_find_dev; } } if (!spidev->rx_buffer) { spidev->rx_buffer = kmalloc(bufsiz, GFP_KERNEL); if (!spidev->rx_buffer) { dev_dbg(&spidev->spi->dev, "open/ENOMEM\n"); status = -ENOMEM; goto err_alloc_rx_buf; } } spidev->users++; filp->private_data = spidev; stream_open(inode, filp); mutex_unlock(&device_list_lock); return 0; err_alloc_rx_buf: kfree(spidev->tx_buffer); spidev->tx_buffer = NULL; err_find_dev: mutex_unlock(&device_list_lock); return status; } static int spidev_release(struct inode *inode, struct file *filp) { struct spidev_data *spidev; mutex_lock(&device_list_lock); spidev = filp->private_data; filp->private_data = NULL; /* last close? */ spidev->users--; if (!spidev->users) { int dofree; kfree(spidev->tx_buffer); spidev->tx_buffer = NULL; kfree(spidev->rx_buffer); spidev->rx_buffer = NULL; spin_lock_irq(&spidev->spi_lock); if (spidev->spi) spidev->speed_hz = spidev->spi->max_speed_hz; /* ... after we unbound from the underlying device? */ dofree = (spidev->spi == NULL); spin_unlock_irq(&spidev->spi_lock); if (dofree) kfree(spidev); } #ifdef CONFIG_SPI_SLAVE spi_slave_abort(spidev->spi); #endif mutex_unlock(&device_list_lock); return 0; } static const struct file_operations spidev_fops = { .owner = THIS_MODULE, /* REVISIT switch to aio primitives, so that userspace * gets more complete API coverage. It'll simplify things * too, except for the locking. */ .write = spidev_write, .read = spidev_read, .unlocked_ioctl = spidev_ioctl, .compat_ioctl = spidev_compat_ioctl, .open = spidev_open, .release = spidev_release, .llseek = no_llseek, }; /*-------------------------------------------------------------------------*/ /* The main reason to have this class is to make mdev/udev create the * /dev/spidevB.C character device nodes exposing our userspace API. * It also simplifies memory management. */ static struct class *spidev_class; #ifdef CONFIG_OF static const struct of_device_id spidev_dt_ids[] = { { .compatible = "rohm,dh2228fv" }, { .compatible = "lineartechnology,ltc2488" }, { .compatible = "ge,achc" }, { .compatible = "semtech,sx1301" }, { .compatible = "lwn,bk4" }, { .compatible = "dh,dhcom-board" }, { .compatible = "menlo,m53cpld" }, {}, }; MODULE_DEVICE_TABLE(of, spidev_dt_ids); #endif #ifdef CONFIG_ACPI /* Dummy SPI devices not to be used in production systems */ #define SPIDEV_ACPI_DUMMY 1 static const struct acpi_device_id spidev_acpi_ids[] = { /* * The ACPI SPT000* devices are only meant for development and * testing. Systems used in production should have a proper ACPI * description of the connected peripheral and they should also use * a proper driver instead of poking directly to the SPI bus. */ { "SPT0001", SPIDEV_ACPI_DUMMY }, { "SPT0002", SPIDEV_ACPI_DUMMY }, { "SPT0003", SPIDEV_ACPI_DUMMY }, {}, }; MODULE_DEVICE_TABLE(acpi, spidev_acpi_ids); static void spidev_probe_acpi(struct spi_device *spi) { const struct acpi_device_id *id; if (!has_acpi_companion(&spi->dev)) return; id = acpi_match_device(spidev_acpi_ids, &spi->dev); if (WARN_ON(!id)) return; if (id->driver_data == SPIDEV_ACPI_DUMMY) dev_warn(&spi->dev, "do not use this driver in production systems!\n"); } #else static inline void spidev_probe_acpi(struct spi_device *spi) {} #endif /*-------------------------------------------------------------------------*/ static int spidev_probe(struct spi_device *spi) { struct spidev_data *spidev; int status; unsigned long minor; /* * spidev should never be referenced in DT without a specific * compatible string, it is a Linux implementation thing * rather than a description of the hardware. */ WARN(spi->dev.of_node && of_device_is_compatible(spi->dev.of_node, "spidev"), "%pOF: buggy DT: spidev listed directly in DT\n", spi->dev.of_node); spidev_probe_acpi(spi); /* Allocate driver data */ spidev = kzalloc(sizeof(*spidev), GFP_KERNEL); if (!spidev) return -ENOMEM; /* Initialize the driver data */ spidev->spi = spi; spin_lock_init(&spidev->spi_lock); mutex_init(&spidev->buf_lock); INIT_LIST_HEAD(&spidev->device_entry); /* If we can allocate a minor number, hook up this device. * Reusing minors is fine so long as udev or mdev is working. */ mutex_lock(&device_list_lock); minor = find_first_zero_bit(minors, N_SPI_MINORS); if (minor < N_SPI_MINORS) { struct device *dev; spidev->devt = MKDEV(SPIDEV_MAJOR, minor); dev = device_create(spidev_class, &spi->dev, spidev->devt, spidev, "spidev%d.%d", spi->master->bus_num, spi->chip_select); status = PTR_ERR_OR_ZERO(dev); } else { dev_dbg(&spi->dev, "no minor number available!\n"); status = -ENODEV; } if (status == 0) { set_bit(minor, minors); list_add(&spidev->device_entry, &device_list); } mutex_unlock(&device_list_lock); spidev->speed_hz = spi->max_speed_hz; if (status == 0) spi_set_drvdata(spi, spidev); else kfree(spidev); return status; } static int spidev_remove(struct spi_device *spi) { struct spidev_data *spidev = spi_get_drvdata(spi); /* make sure ops on existing fds can abort cleanly */ spin_lock_irq(&spidev->spi_lock); spidev->spi = NULL; spin_unlock_irq(&spidev->spi_lock); /* prevent new opens */ mutex_lock(&device_list_lock); list_del(&spidev->device_entry); device_destroy(spidev_class, spidev->devt); clear_bit(MINOR(spidev->devt), minors); if (spidev->users == 0) kfree(spidev); mutex_unlock(&device_list_lock); return 0; } static struct spi_driver spidev_spi_driver = { .driver = { .name = "spidev", .of_match_table = of_match_ptr(spidev_dt_ids), .acpi_match_table = ACPI_PTR(spidev_acpi_ids), }, .probe = spidev_probe, .remove = spidev_remove, /* NOTE: suspend/resume methods are not necessary here. * We don't do anything except pass the requests to/from * the underlying controller. The refrigerator handles * most issues; the controller driver handles the rest. */ }; /*-------------------------------------------------------------------------*/ static int __init spidev_init(void) { int status; /* Claim our 256 reserved device numbers. Then register a class * that will key udev/mdev to add/remove /dev nodes. Last, register * the driver which manages those device numbers. */ BUILD_BUG_ON(N_SPI_MINORS > 256); status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops); if (status < 0) return status; spidev_class = class_create(THIS_MODULE, "spidev"); if (IS_ERR(spidev_class)) { unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name); return PTR_ERR(spidev_class); } status = spi_register_driver(&spidev_spi_driver); if (status < 0) { class_destroy(spidev_class); unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name); } return status; } module_init(spidev_init); static void __exit spidev_exit(void) { spi_unregister_driver(&spidev_spi_driver); class_destroy(spidev_class); unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name); } module_exit(spidev_exit); MODULE_AUTHOR("Andrea Paterniani, "); MODULE_DESCRIPTION("User mode SPI device interface"); MODULE_LICENSE("GPL"); MODULE_ALIAS("spi:spidev");