diff options
Diffstat (limited to 'drivers/spi/spidev.c')
| -rw-r--r-- | drivers/spi/spidev.c | 907 |
1 files changed, 907 insertions, 0 deletions
diff --git a/drivers/spi/spidev.c b/drivers/spi/spidev.c new file mode 100644 index 0000000000..d13dc15cc1 --- /dev/null +++ b/drivers/spi/spidev.c @@ -0,0 +1,907 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Simple synchronous userspace interface to SPI devices + * + * Copyright (C) 2006 SWAPP + * Andrea Paterniani <a.paterniani@swapp-eng.it> + * Copyright (C) 2007 David Brownell (simplification, cleanup) + */ + +#include <linux/init.h> +#include <linux/ioctl.h> +#include <linux/fs.h> +#include <linux/device.h> +#include <linux/err.h> +#include <linux/list.h> +#include <linux/errno.h> +#include <linux/mod_devicetable.h> +#include <linux/module.h> +#include <linux/mutex.h> +#include <linux/property.h> +#include <linux/slab.h> +#include <linux/compat.h> + +#include <linux/spi/spi.h> +#include <linux/spi/spidev.h> + +#include <linux/uaccess.h> + + +/* + * 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); + +static_assert(N_SPI_MINORS > 0 && N_SPI_MINORS <= 256); + +/* 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_MODE_X_MASK | SPI_CS_HIGH \ + | SPI_LSB_FIRST | SPI_3WIRE | SPI_LOOP \ + | SPI_NO_CS | SPI_READY | SPI_TX_DUAL \ + | SPI_TX_QUAD | SPI_TX_OCTAL | SPI_RX_DUAL \ + | SPI_RX_QUAD | SPI_RX_OCTAL \ + | SPI_RX_CPHA_FLIP | SPI_3WIRE_HIZ \ + | SPI_MOSI_IDLE_LOW) + +struct spidev_data { + dev_t devt; + struct mutex 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_unlocked(struct spi_device *spi, struct spi_message *message) +{ + ssize_t status; + + status = spi_sync(spi, message); + if (status == 0) + status = message->actual_length; + + return status; +} + +static ssize_t +spidev_sync(struct spidev_data *spidev, struct spi_message *message) +{ + ssize_t status; + struct spi_device *spi; + + mutex_lock(&spidev->spi_lock); + spi = spidev->spi; + + if (spi == NULL) + status = -ESHUTDOWN; + else + status = spidev_sync_unlocked(spi, message); + + mutex_unlock(&spidev->spi_lock); + 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; + + /* 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; + 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++) { + /* Ensure that also following allocations from rx_buf/tx_buf will meet + * DMA alignment requirements. + */ + unsigned int len_aligned = ALIGN(u_tmp->len, ARCH_DMA_MINALIGN); + + 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 += len_aligned; + if (rx_total > bufsiz) { + status = -EMSGSIZE; + goto done; + } + k_tmp->rx_buf = rx_buf; + rx_buf += len_aligned; + } + if (u_tmp->tx_buf) { + /* this transfer needs space in TX bounce buffer */ + tx_total += len_aligned; + 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 += len_aligned; + } + + 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.value = u_tmp->delay_usecs; + k_tmp->delay.unit = SPI_DELAY_UNIT_USECS; + k_tmp->speed_hz = u_tmp->speed_hz; + k_tmp->word_delay.value = u_tmp->word_delay_usecs; + k_tmp->word_delay.unit = SPI_DELAY_UNIT_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", + k_tmp->len, + k_tmp->rx_buf ? "rx " : "", + k_tmp->tx_buf ? "tx " : "", + k_tmp->cs_change ? "cs " : "", + k_tmp->bits_per_word ? : spidev->spi->bits_per_word, + k_tmp->delay.value, + k_tmp->word_delay.value, + k_tmp->speed_hz ? : spidev->spi->max_speed_hz); +#endif + spi_message_add_tail(k_tmp, &msg); + } + + status = spidev_sync_unlocked(spidev->spi, &msg); + if (status < 0) + goto done; + + /* copy any rx data out of bounce buffer */ + for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers; + n; + n--, k_tmp++, u_tmp++) { + if (u_tmp->rx_buf) { + if (copy_to_user((u8 __user *) + (uintptr_t) u_tmp->rx_buf, k_tmp->rx_buf, + u_tmp->len)) { + status = -EFAULT; + goto done; + } + } + } + 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; + mutex_lock(&spidev->spi_lock); + spi = spi_dev_get(spidev->spi); + if (spi == NULL) { + mutex_unlock(&spidev->spi_lock); + 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: + case SPI_IOC_RD_MODE32: + tmp = spi->mode; + + { + struct spi_controller *ctlr = spi->controller; + + if (ctlr->use_gpio_descriptors && ctlr->cs_gpiods && + ctlr->cs_gpiods[spi_get_chipselect(spi, 0)]) + tmp &= ~SPI_CS_HIGH; + } + + if (cmd == SPI_IOC_RD_MODE) + retval = put_user(tmp & SPI_MODE_MASK, + (__u8 __user *)arg); + else + retval = put_user(tmp & 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_get_chipselect(spi, 0)]) + tmp |= SPI_CS_HIGH; + + tmp |= spi->mode & ~SPI_MODE_MASK; + spi->mode = tmp & SPI_MODE_USER_MASK; + 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: { + u32 save; + + retval = get_user(tmp, (__u32 __user *)arg); + if (retval) + break; + if (tmp == 0) { + retval = -EINVAL; + break; + } + + save = spi->max_speed_hz; + + spi->max_speed_hz = tmp; + retval = spi_setup(spi); + if (retval == 0) { + spidev->speed_hz = tmp; + dev_dbg(&spi->dev, "%d Hz (max)\n", spidev->speed_hz); + } + + 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); + mutex_unlock(&spidev->spi_lock); + 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; + mutex_lock(&spidev->spi_lock); + spi = spi_dev_get(spidev->spi); + if (spi == NULL) { + mutex_unlock(&spidev->spi_lock); + 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); + mutex_unlock(&spidev->spi_lock); + 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 = NULL, *iter; + int status = -ENXIO; + + mutex_lock(&device_list_lock); + + list_for_each_entry(iter, &device_list, device_entry) { + if (iter->devt == inode->i_rdev) { + status = 0; + spidev = iter; + break; + } + } + + if (!spidev) { + 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) { + status = -ENOMEM; + goto err_find_dev; + } + } + + if (!spidev->rx_buffer) { + spidev->rx_buffer = kmalloc(bufsiz, GFP_KERNEL); + if (!spidev->rx_buffer) { + 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; + int dofree; + + mutex_lock(&device_list_lock); + spidev = filp->private_data; + filp->private_data = NULL; + + mutex_lock(&spidev->spi_lock); + /* ... after we unbound from the underlying device? */ + dofree = (spidev->spi == NULL); + mutex_unlock(&spidev->spi_lock); + + /* last close? */ + spidev->users--; + if (!spidev->users) { + + kfree(spidev->tx_buffer); + spidev->tx_buffer = NULL; + + kfree(spidev->rx_buffer); + spidev->rx_buffer = NULL; + + if (dofree) + kfree(spidev); + else + spidev->speed_hz = spidev->spi->max_speed_hz; + } +#ifdef CONFIG_SPI_SLAVE + if (!dofree) + 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; + +static const struct spi_device_id spidev_spi_ids[] = { + { .name = "dh2228fv" }, + { .name = "ltc2488" }, + { .name = "sx1301" }, + { .name = "bk4" }, + { .name = "dhcom-board" }, + { .name = "m53cpld" }, + { .name = "spi-petra" }, + { .name = "spi-authenta" }, + { .name = "em3581" }, + { .name = "si3210" }, + {}, +}; +MODULE_DEVICE_TABLE(spi, spidev_spi_ids); + +/* + * 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. + */ +static int spidev_of_check(struct device *dev) +{ + if (device_property_match_string(dev, "compatible", "spidev") < 0) + return 0; + + dev_err(dev, "spidev listed directly in DT is not supported\n"); + return -EINVAL; +} + +static const struct of_device_id spidev_dt_ids[] = { + { .compatible = "cisco,spi-petra", .data = &spidev_of_check }, + { .compatible = "dh,dhcom-board", .data = &spidev_of_check }, + { .compatible = "lineartechnology,ltc2488", .data = &spidev_of_check }, + { .compatible = "lwn,bk4", .data = &spidev_of_check }, + { .compatible = "menlo,m53cpld", .data = &spidev_of_check }, + { .compatible = "micron,spi-authenta", .data = &spidev_of_check }, + { .compatible = "rohm,dh2228fv", .data = &spidev_of_check }, + { .compatible = "semtech,sx1301", .data = &spidev_of_check }, + { .compatible = "silabs,em3581", .data = &spidev_of_check }, + { .compatible = "silabs,si3210", .data = &spidev_of_check }, + {}, +}; +MODULE_DEVICE_TABLE(of, spidev_dt_ids); + +/* Dummy SPI devices not to be used in production systems */ +static int spidev_acpi_check(struct device *dev) +{ + dev_warn(dev, "do not use this driver in production systems!\n"); + return 0; +} + +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", (kernel_ulong_t)&spidev_acpi_check }, + { "SPT0002", (kernel_ulong_t)&spidev_acpi_check }, + { "SPT0003", (kernel_ulong_t)&spidev_acpi_check }, + {}, +}; +MODULE_DEVICE_TABLE(acpi, spidev_acpi_ids); + +/*-------------------------------------------------------------------------*/ + +static int spidev_probe(struct spi_device *spi) +{ + int (*match)(struct device *dev); + struct spidev_data *spidev; + int status; + unsigned long minor; + + match = device_get_match_data(&spi->dev); + if (match) { + status = match(&spi->dev); + if (status) + return status; + } + + /* Allocate driver data */ + spidev = kzalloc(sizeof(*spidev), GFP_KERNEL); + if (!spidev) + return -ENOMEM; + + /* Initialize the driver data */ + spidev->spi = spi; + mutex_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_get_chipselect(spi, 0)); + 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 void spidev_remove(struct spi_device *spi) +{ + struct spidev_data *spidev = spi_get_drvdata(spi); + + /* prevent new opens */ + mutex_lock(&device_list_lock); + /* make sure ops on existing fds can abort cleanly */ + mutex_lock(&spidev->spi_lock); + spidev->spi = NULL; + mutex_unlock(&spidev->spi_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); +} + +static struct spi_driver spidev_spi_driver = { + .driver = { + .name = "spidev", + .of_match_table = spidev_dt_ids, + .acpi_match_table = spidev_acpi_ids, + }, + .probe = spidev_probe, + .remove = spidev_remove, + .id_table = spidev_spi_ids, + + /* 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. + */ + status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops); + if (status < 0) + return status; + + spidev_class = class_create("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, <a.paterniani@swapp-eng.it>"); +MODULE_DESCRIPTION("User mode SPI device interface"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("spi:spidev"); |