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path: root/drivers/spi/spidev.c
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Diffstat (limited to 'drivers/spi/spidev.c')
-rw-r--r--drivers/spi/spidev.c584
1 files changed, 584 insertions, 0 deletions
diff --git a/drivers/spi/spidev.c b/drivers/spi/spidev.c
new file mode 100644
index 000000000000..c0a6dce800a3
--- /dev/null
+++ b/drivers/spi/spidev.c
@@ -0,0 +1,584 @@
+/*
+ * spidev.c -- 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/ioctl.h>
+#include <linux/fs.h>
+#include <linux/device.h>
+#include <linux/list.h>
+#include <linux/errno.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+
+#include <linux/spi/spi.h>
+#include <linux/spi/spidev.h>
+
+#include <asm/uaccess.h>
+
+
+/*
+ * This supports acccess 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 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 unsigned long minors[N_SPI_MINORS / BITS_PER_LONG];
+
+
+/* Bit masks for spi_device.mode management */
+#define SPI_MODE_MASK (SPI_CPHA | SPI_CPOL)
+
+
+struct spidev_data {
+ struct device dev;
+ struct spi_device *spi;
+ struct list_head device_entry;
+
+ struct mutex buf_lock;
+ unsigned users;
+ u8 *buffer;
+};
+
+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");
+
+/*-------------------------------------------------------------------------*/
+
+/* 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;
+ struct spi_device *spi;
+ ssize_t status = 0;
+
+ /* chipselect only toggles at start or end of operation */
+ if (count > bufsiz)
+ return -EMSGSIZE;
+
+ spidev = filp->private_data;
+ spi = spidev->spi;
+
+ mutex_lock(&spidev->buf_lock);
+ status = spi_read(spi, spidev->buffer, count);
+ if (status == 0) {
+ unsigned long missing;
+
+ missing = copy_to_user(buf, spidev->buffer, count);
+ if (count && missing == count)
+ status = -EFAULT;
+ else
+ status = count - 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;
+ struct spi_device *spi;
+ 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;
+ spi = spidev->spi;
+
+ mutex_lock(&spidev->buf_lock);
+ missing = copy_from_user(spidev->buffer, buf, count);
+ if (missing == 0) {
+ status = spi_write(spi, spidev->buffer, count);
+ if (status == 0)
+ status = 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;
+ struct spi_device *spi = spidev->spi;
+ unsigned n, total;
+ u8 *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.
+ */
+ mutex_lock(&spidev->buf_lock);
+ buf = spidev->buffer;
+ 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;
+
+ if (u_tmp->rx_buf) {
+ k_tmp->rx_buf = buf;
+ if (!access_ok(VERIFY_WRITE, u_tmp->rx_buf, u_tmp->len))
+ goto done;
+ }
+ if (u_tmp->tx_buf) {
+ k_tmp->tx_buf = buf;
+ if (copy_from_user(buf, (const u8 __user *)u_tmp->tx_buf,
+ u_tmp->len))
+ goto done;
+ }
+
+ total += k_tmp->len;
+ if (total > bufsiz) {
+ status = -EMSGSIZE;
+ goto done;
+ }
+ buf += k_tmp->len;
+
+ k_tmp->cs_change = !!u_tmp->cs_change;
+ 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;
+#ifdef VERBOSE
+ dev_dbg(&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 ? : spi->bits_per_word,
+ u_tmp->delay_usecs,
+ u_tmp->speed_hz ? : spi->max_speed_hz);
+#endif
+ spi_message_add_tail(k_tmp, &msg);
+ }
+
+ status = spi_sync(spi, &msg);
+ if (status < 0)
+ goto done;
+
+ /* copy any rx data out of bounce buffer */
+ buf = spidev->buffer;
+ for (n = n_xfers, u_tmp = u_xfers; n; n--, u_tmp++) {
+ if (u_tmp->rx_buf) {
+ if (__copy_to_user((u8 __user *)u_tmp->rx_buf, buf,
+ u_tmp->len)) {
+ status = -EFAULT;
+ goto done;
+ }
+ }
+ buf += u_tmp->len;
+ }
+ status = total;
+
+done:
+ mutex_unlock(&spidev->buf_lock);
+ kfree(k_xfers);
+ return status;
+}
+
+static int
+spidev_ioctl(struct inode *inode, 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;
+
+ spidev = filp->private_data;
+ spi = spidev->spi;
+
+ 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_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(spi->max_speed_hz, (__u32 __user *)arg);
+ break;
+
+ /* write requests */
+ case SPI_IOC_WR_MODE:
+ retval = __get_user(tmp, (u8 __user *)arg);
+ if (retval == 0) {
+ u8 save = spi->mode;
+
+ if (tmp & ~SPI_MODE_MASK) {
+ retval = -EINVAL;
+ break;
+ }
+
+ tmp |= spi->mode & ~SPI_MODE_MASK;
+ spi->mode = (u8)tmp;
+ retval = spi_setup(spi);
+ if (retval < 0)
+ spi->mode = save;
+ else
+ dev_dbg(&spi->dev, "spi mode %02x\n", tmp);
+ }
+ break;
+ case SPI_IOC_WR_LSB_FIRST:
+ retval = __get_user(tmp, (__u8 __user *)arg);
+ if (retval == 0) {
+ u8 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)
+ spi->max_speed_hz = save;
+ else
+ dev_dbg(&spi->dev, "%d Hz (max)\n", tmp);
+ }
+ break;
+
+ default:
+ /* segmented and/or full-duplex I/O request */
+ if (_IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0))
+ || _IOC_DIR(cmd) != _IOC_WRITE)
+ return -ENOTTY;
+
+ tmp = _IOC_SIZE(cmd);
+ if ((tmp % sizeof(struct spi_ioc_transfer)) != 0) {
+ retval = -EINVAL;
+ break;
+ }
+ n_ioc = tmp / sizeof(struct spi_ioc_transfer);
+ if (n_ioc == 0)
+ break;
+
+ /* copy into scratch area */
+ ioc = kmalloc(tmp, GFP_KERNEL);
+ if (!ioc) {
+ retval = -ENOMEM;
+ break;
+ }
+ if (__copy_from_user(ioc, (void __user *)arg, tmp)) {
+ retval = -EFAULT;
+ break;
+ }
+
+ /* translate to spi_message, execute */
+ retval = spidev_message(spidev, ioc, n_ioc);
+ kfree(ioc);
+ break;
+ }
+ return retval;
+}
+
+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->dev.devt == inode->i_rdev) {
+ status = 0;
+ break;
+ }
+ }
+ if (status == 0) {
+ if (!spidev->buffer) {
+ spidev->buffer = kmalloc(bufsiz, GFP_KERNEL);
+ if (!spidev->buffer) {
+ dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
+ status = -ENOMEM;
+ }
+ }
+ if (status == 0) {
+ spidev->users++;
+ filp->private_data = spidev;
+ nonseekable_open(inode, filp);
+ }
+ } else
+ pr_debug("spidev: nothing for minor %d\n", iminor(inode));
+
+ 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;
+ spidev->users--;
+ if (!spidev->users) {
+ kfree(spidev->buffer);
+ spidev->buffer = NULL;
+ }
+ mutex_unlock(&device_list_lock);
+
+ return status;
+}
+
+static 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,
+ .ioctl = spidev_ioctl,
+ .open = spidev_open,
+ .release = spidev_release,
+};
+
+/*-------------------------------------------------------------------------*/
+
+/* 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 void spidev_classdev_release(struct device *dev)
+{
+ struct spidev_data *spidev;
+
+ spidev = container_of(dev, struct spidev_data, dev);
+ kfree(spidev);
+}
+
+static struct class spidev_class = {
+ .name = "spidev",
+ .owner = THIS_MODULE,
+ .dev_release = spidev_classdev_release,
+};
+
+/*-------------------------------------------------------------------------*/
+
+static int spidev_probe(struct spi_device *spi)
+{
+ struct spidev_data *spidev;
+ int status;
+ unsigned long minor;
+
+ /* Allocate driver data */
+ spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);
+ if (!spidev)
+ return -ENOMEM;
+
+ /* Initialize the driver data */
+ spidev->spi = spi;
+ 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, ARRAY_SIZE(minors));
+ if (minor < N_SPI_MINORS) {
+ spidev->dev.parent = &spi->dev;
+ spidev->dev.class = &spidev_class;
+ spidev->dev.devt = MKDEV(SPIDEV_MAJOR, minor);
+ snprintf(spidev->dev.bus_id, sizeof spidev->dev.bus_id,
+ "spidev%d.%d",
+ spi->master->bus_num, spi->chip_select);
+ status = device_register(&spidev->dev);
+ } else {
+ dev_dbg(&spi->dev, "no minor number available!\n");
+ status = -ENODEV;
+ }
+ if (status == 0) {
+ set_bit(minor, minors);
+ dev_set_drvdata(&spi->dev, spidev);
+ list_add(&spidev->device_entry, &device_list);
+ }
+ mutex_unlock(&device_list_lock);
+
+ if (status != 0)
+ kfree(spidev);
+
+ return status;
+}
+
+static int spidev_remove(struct spi_device *spi)
+{
+ struct spidev_data *spidev = dev_get_drvdata(&spi->dev);
+
+ mutex_lock(&device_list_lock);
+
+ list_del(&spidev->device_entry);
+ dev_set_drvdata(&spi->dev, NULL);
+ clear_bit(MINOR(spidev->dev.devt), minors);
+ device_unregister(&spidev->dev);
+
+ mutex_unlock(&device_list_lock);
+
+ return 0;
+}
+
+static struct spi_driver spidev_spi = {
+ .driver = {
+ .name = "spidev",
+ .owner = THIS_MODULE,
+ },
+ .probe = spidev_probe,
+ .remove = __devexit_p(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;
+
+ status = class_register(&spidev_class);
+ if (status < 0) {
+ unregister_chrdev(SPIDEV_MAJOR, spidev_spi.driver.name);
+ return status;
+ }
+
+ status = spi_register_driver(&spidev_spi);
+ if (status < 0) {
+ class_unregister(&spidev_class);
+ unregister_chrdev(SPIDEV_MAJOR, spidev_spi.driver.name);
+ }
+ return status;
+}
+module_init(spidev_init);
+
+static void __exit spidev_exit(void)
+{
+ spi_unregister_driver(&spidev_spi);
+ class_unregister(&spidev_class);
+ unregister_chrdev(SPIDEV_MAJOR, spidev_spi.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");
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-28 02:17:42 +0000