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");