--- /dev/null
+/*
+ * 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)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/init.h>
+#include <linux/module.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/mutex.h>
+#include <linux/slab.h>
+#include <linux/compat.h>
+#include <linux/of.h>
+#include <linux/of_device.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);
+
+
+/* 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");
+
+/*-------------------------------------------------------------------------*/
+
+/*
+ * We can't use the standard synchronous wrappers for file I/O; we
+ * need to protect against async removal of the underlying spi_device.
+ */
+static void spidev_complete(void *arg)
+{
+ complete(arg);
+}
+
+static ssize_t
+spidev_sync(struct spidev_data *spidev, struct spi_message *message)
+{
+ DECLARE_COMPLETION_ONSTACK(done);
+ int status;
+
+ message->complete = spidev_complete;
+ message->context = &done;
+
+ spin_lock_irq(&spidev->spi_lock);
+ if (spidev->spi == NULL)
+ status = -ESHUTDOWN;
+ else
+ status = spi_async(spidev->spi, message);
+ spin_unlock_irq(&spidev->spi_lock);
+
+ if (status == 0) {
+ wait_for_completion(&done);
+ status = message->status;
+ 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;
+ if (!access_ok(VERIFY_WRITE, (u8 __user *)
+ (uintptr_t) u_tmp->rx_buf,
+ u_tmp->len))
+ goto done;
+ 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;
+ if (!k_tmp->speed_hz)
+ k_tmp->speed_hz = spidev->speed_hz;
+#ifdef VERBOSE
+ dev_dbg(&spidev->spi->dev,
+ " xfer len %zd %s%s%s%dbits %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->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)
+{
+ struct spi_ioc_transfer *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 */
+ ioc = kmalloc(tmp, GFP_KERNEL);
+ if (!ioc)
+ return ERR_PTR(-ENOMEM);
+ if (__copy_from_user(ioc, u_ioc, tmp)) {
+ kfree(ioc);
+ return ERR_PTR(-EFAULT);
+ }
+ return ioc;
+}
+
+static long
+spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
+{
+ int err = 0;
+ 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;
+
+ /* Check access direction once here; don't repeat below.
+ * IOC_DIR is from the user perspective, while access_ok is
+ * from the kernel perspective; so they look reversed.
+ */
+ if (_IOC_DIR(cmd) & _IOC_READ)
+ err = !access_ok(VERIFY_WRITE,
+ (void __user *)arg, _IOC_SIZE(cmd));
+ if (err == 0 && _IOC_DIR(cmd) & _IOC_WRITE)
+ err = !access_ok(VERIFY_READ,
+ (void __user *)arg, _IOC_SIZE(cmd));
+ if (err)
+ return -EFAULT;
+
+ /* 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) {
+ u32 save = spi->mode;
+
+ if (tmp & ~SPI_MODE_MASK) {
+ retval = -EINVAL;
+ break;
+ }
+
+ 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);
+ if (!access_ok(VERIFY_READ, u_ioc, _IOC_SIZE(cmd)))
+ return -EFAULT;
+
+ /* 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;
+ nonseekable_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 status = 0;
+
+ 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;
+
+ spidev->speed_hz = spidev->spi->max_speed_hz;
+
+ /* ... after we unbound from the underlying device? */
+ spin_lock_irq(&spidev->spi_lock);
+ dofree = (spidev->spi == NULL);
+ spin_unlock_irq(&spidev->spi_lock);
+
+ if (dofree)
+ kfree(spidev);
+ }
+ mutex_unlock(&device_list_lock);
+
+ return status;
+}
+
+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" },
+ {},
+};
+MODULE_DEVICE_TABLE(of, spidev_dt_ids);
+#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
+ * compatbile string, it is a Linux implementation thing
+ * rather than a description of the hardware.
+ */
+ if (spi->dev.of_node && !of_match_device(spidev_dt_ids, &spi->dev)) {
+ dev_err(&spi->dev, "buggy DT: spidev listed directly in DT\n");
+ WARN_ON(spi->dev.of_node &&
+ !of_match_device(spidev_dt_ids, &spi->dev));
+ }
+
+ /* 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",
+ .owner = THIS_MODULE,
+ .of_match_table = of_match_ptr(spidev_dt_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, <a.paterniani@swapp-eng.it>");
+MODULE_DESCRIPTION("User mode SPI device interface");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("spi:spidev");
Code Review / kvmfornfv.git / blobdiff