diff options
Diffstat (limited to 'drivers/spi/spidev.c')
| -rw-r--r-- | drivers/spi/spidev.c | 584 |
1 files changed, 584 insertions, 0 deletions
diff --git a/drivers/spi/spidev.c b/drivers/spi/spidev.c new file mode 100644 index 0000000..c0a6dce --- /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"); |
