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![Greg Kroah-Hartman](/assets/img/avatar_default.png)
Now that device_create() has been audited, rename things back to the original call to be sane. Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
683 lines
17 KiB
C
683 lines
17 KiB
C
/*
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* spidev.c -- simple synchronous userspace interface to SPI devices
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*
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* Copyright (C) 2006 SWAPP
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* Andrea Paterniani <a.paterniani@swapp-eng.it>
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* Copyright (C) 2007 David Brownell (simplification, cleanup)
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/ioctl.h>
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#include <linux/fs.h>
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#include <linux/device.h>
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#include <linux/err.h>
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#include <linux/list.h>
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#include <linux/errno.h>
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#include <linux/mutex.h>
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#include <linux/slab.h>
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#include <linux/smp_lock.h>
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#include <linux/spi/spi.h>
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#include <linux/spi/spidev.h>
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#include <asm/uaccess.h>
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/*
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* This supports acccess to SPI devices using normal userspace I/O calls.
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* Note that while traditional UNIX/POSIX I/O semantics are half duplex,
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* and often mask message boundaries, full SPI support requires full duplex
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* transfers. There are several kinds of of internal message boundaries to
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* handle chipselect management and other protocol options.
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*
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* SPI has a character major number assigned. We allocate minor numbers
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* dynamically using a bitmask. You must use hotplug tools, such as udev
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* (or mdev with busybox) to create and destroy the /dev/spidevB.C device
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* nodes, since there is no fixed association of minor numbers with any
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* particular SPI bus or device.
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*/
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#define SPIDEV_MAJOR 153 /* assigned */
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#define N_SPI_MINORS 32 /* ... up to 256 */
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static unsigned long minors[N_SPI_MINORS / BITS_PER_LONG];
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/* Bit masks for spi_device.mode management. Note that incorrect
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* settings for CS_HIGH and 3WIRE can cause *lots* of trouble for other
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* devices on a shared bus: CS_HIGH, because this device will be
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* active when it shouldn't be; 3WIRE, because when active it won't
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* behave as it should.
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*
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* REVISIT should changing those two modes be privileged?
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*/
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#define SPI_MODE_MASK (SPI_CPHA | SPI_CPOL | SPI_CS_HIGH \
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| SPI_LSB_FIRST | SPI_3WIRE | SPI_LOOP)
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struct spidev_data {
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dev_t devt;
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spinlock_t spi_lock;
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struct spi_device *spi;
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struct list_head device_entry;
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/* buffer is NULL unless this device is open (users > 0) */
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struct mutex buf_lock;
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unsigned users;
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u8 *buffer;
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};
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static LIST_HEAD(device_list);
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static DEFINE_MUTEX(device_list_lock);
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static unsigned bufsiz = 4096;
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module_param(bufsiz, uint, S_IRUGO);
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MODULE_PARM_DESC(bufsiz, "data bytes in biggest supported SPI message");
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/*-------------------------------------------------------------------------*/
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/*
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* We can't use the standard synchronous wrappers for file I/O; we
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* need to protect against async removal of the underlying spi_device.
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*/
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static void spidev_complete(void *arg)
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{
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complete(arg);
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}
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static ssize_t
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spidev_sync(struct spidev_data *spidev, struct spi_message *message)
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{
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DECLARE_COMPLETION_ONSTACK(done);
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int status;
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message->complete = spidev_complete;
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message->context = &done;
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spin_lock_irq(&spidev->spi_lock);
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if (spidev->spi == NULL)
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status = -ESHUTDOWN;
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else
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status = spi_async(spidev->spi, message);
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spin_unlock_irq(&spidev->spi_lock);
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if (status == 0) {
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wait_for_completion(&done);
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status = message->status;
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if (status == 0)
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status = message->actual_length;
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}
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return status;
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}
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static inline ssize_t
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spidev_sync_write(struct spidev_data *spidev, size_t len)
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{
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struct spi_transfer t = {
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.tx_buf = spidev->buffer,
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.len = len,
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};
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struct spi_message m;
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spi_message_init(&m);
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spi_message_add_tail(&t, &m);
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return spidev_sync(spidev, &m);
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}
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static inline ssize_t
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spidev_sync_read(struct spidev_data *spidev, size_t len)
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{
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struct spi_transfer t = {
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.rx_buf = spidev->buffer,
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.len = len,
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};
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struct spi_message m;
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spi_message_init(&m);
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spi_message_add_tail(&t, &m);
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return spidev_sync(spidev, &m);
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}
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/*-------------------------------------------------------------------------*/
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/* Read-only message with current device setup */
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static ssize_t
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spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
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{
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struct spidev_data *spidev;
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ssize_t status = 0;
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/* chipselect only toggles at start or end of operation */
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if (count > bufsiz)
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return -EMSGSIZE;
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spidev = filp->private_data;
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mutex_lock(&spidev->buf_lock);
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status = spidev_sync_read(spidev, count);
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if (status > 0) {
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unsigned long missing;
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missing = copy_to_user(buf, spidev->buffer, status);
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if (missing == status)
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status = -EFAULT;
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else
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status = status - missing;
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}
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mutex_unlock(&spidev->buf_lock);
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return status;
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}
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/* Write-only message with current device setup */
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static ssize_t
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spidev_write(struct file *filp, const char __user *buf,
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size_t count, loff_t *f_pos)
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{
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struct spidev_data *spidev;
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ssize_t status = 0;
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unsigned long missing;
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/* chipselect only toggles at start or end of operation */
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if (count > bufsiz)
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return -EMSGSIZE;
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spidev = filp->private_data;
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mutex_lock(&spidev->buf_lock);
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missing = copy_from_user(spidev->buffer, buf, count);
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if (missing == 0) {
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status = spidev_sync_write(spidev, count);
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} else
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status = -EFAULT;
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mutex_unlock(&spidev->buf_lock);
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return status;
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}
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static int spidev_message(struct spidev_data *spidev,
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struct spi_ioc_transfer *u_xfers, unsigned n_xfers)
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{
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struct spi_message msg;
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struct spi_transfer *k_xfers;
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struct spi_transfer *k_tmp;
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struct spi_ioc_transfer *u_tmp;
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unsigned n, total;
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u8 *buf;
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int status = -EFAULT;
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spi_message_init(&msg);
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k_xfers = kcalloc(n_xfers, sizeof(*k_tmp), GFP_KERNEL);
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if (k_xfers == NULL)
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return -ENOMEM;
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/* Construct spi_message, copying any tx data to bounce buffer.
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* We walk the array of user-provided transfers, using each one
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* to initialize a kernel version of the same transfer.
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*/
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buf = spidev->buffer;
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total = 0;
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for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers;
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n;
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n--, k_tmp++, u_tmp++) {
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k_tmp->len = u_tmp->len;
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total += k_tmp->len;
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if (total > bufsiz) {
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status = -EMSGSIZE;
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goto done;
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}
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if (u_tmp->rx_buf) {
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k_tmp->rx_buf = buf;
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if (!access_ok(VERIFY_WRITE, (u8 __user *)
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(uintptr_t) u_tmp->rx_buf,
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u_tmp->len))
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goto done;
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}
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if (u_tmp->tx_buf) {
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k_tmp->tx_buf = buf;
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if (copy_from_user(buf, (const u8 __user *)
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(uintptr_t) u_tmp->tx_buf,
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u_tmp->len))
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goto done;
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}
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buf += k_tmp->len;
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k_tmp->cs_change = !!u_tmp->cs_change;
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k_tmp->bits_per_word = u_tmp->bits_per_word;
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k_tmp->delay_usecs = u_tmp->delay_usecs;
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k_tmp->speed_hz = u_tmp->speed_hz;
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#ifdef VERBOSE
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dev_dbg(&spi->dev,
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" xfer len %zd %s%s%s%dbits %u usec %uHz\n",
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u_tmp->len,
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u_tmp->rx_buf ? "rx " : "",
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u_tmp->tx_buf ? "tx " : "",
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u_tmp->cs_change ? "cs " : "",
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u_tmp->bits_per_word ? : spi->bits_per_word,
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u_tmp->delay_usecs,
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u_tmp->speed_hz ? : spi->max_speed_hz);
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#endif
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spi_message_add_tail(k_tmp, &msg);
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}
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status = spidev_sync(spidev, &msg);
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if (status < 0)
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goto done;
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/* copy any rx data out of bounce buffer */
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buf = spidev->buffer;
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for (n = n_xfers, u_tmp = u_xfers; n; n--, u_tmp++) {
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if (u_tmp->rx_buf) {
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if (__copy_to_user((u8 __user *)
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(uintptr_t) u_tmp->rx_buf, buf,
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u_tmp->len)) {
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status = -EFAULT;
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goto done;
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}
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}
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buf += u_tmp->len;
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}
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status = total;
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done:
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kfree(k_xfers);
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return status;
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}
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static long
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spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
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{
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int err = 0;
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int retval = 0;
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struct spidev_data *spidev;
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struct spi_device *spi;
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u32 tmp;
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unsigned n_ioc;
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struct spi_ioc_transfer *ioc;
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/* Check type and command number */
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if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC)
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return -ENOTTY;
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/* Check access direction once here; don't repeat below.
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* IOC_DIR is from the user perspective, while access_ok is
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* from the kernel perspective; so they look reversed.
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*/
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if (_IOC_DIR(cmd) & _IOC_READ)
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err = !access_ok(VERIFY_WRITE,
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(void __user *)arg, _IOC_SIZE(cmd));
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if (err == 0 && _IOC_DIR(cmd) & _IOC_WRITE)
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err = !access_ok(VERIFY_READ,
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(void __user *)arg, _IOC_SIZE(cmd));
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if (err)
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return -EFAULT;
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/* guard against device removal before, or while,
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* we issue this ioctl.
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*/
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spidev = filp->private_data;
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spin_lock_irq(&spidev->spi_lock);
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spi = spi_dev_get(spidev->spi);
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spin_unlock_irq(&spidev->spi_lock);
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if (spi == NULL)
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return -ESHUTDOWN;
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/* use the buffer lock here for triple duty:
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* - prevent I/O (from us) so calling spi_setup() is safe;
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* - prevent concurrent SPI_IOC_WR_* from morphing
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* data fields while SPI_IOC_RD_* reads them;
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* - SPI_IOC_MESSAGE needs the buffer locked "normally".
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*/
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mutex_lock(&spidev->buf_lock);
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switch (cmd) {
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/* read requests */
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case SPI_IOC_RD_MODE:
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retval = __put_user(spi->mode & SPI_MODE_MASK,
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(__u8 __user *)arg);
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break;
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case SPI_IOC_RD_LSB_FIRST:
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retval = __put_user((spi->mode & SPI_LSB_FIRST) ? 1 : 0,
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(__u8 __user *)arg);
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break;
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case SPI_IOC_RD_BITS_PER_WORD:
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retval = __put_user(spi->bits_per_word, (__u8 __user *)arg);
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break;
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case SPI_IOC_RD_MAX_SPEED_HZ:
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retval = __put_user(spi->max_speed_hz, (__u32 __user *)arg);
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break;
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/* write requests */
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case SPI_IOC_WR_MODE:
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retval = __get_user(tmp, (u8 __user *)arg);
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if (retval == 0) {
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u8 save = spi->mode;
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if (tmp & ~SPI_MODE_MASK) {
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retval = -EINVAL;
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break;
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}
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tmp |= spi->mode & ~SPI_MODE_MASK;
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spi->mode = (u8)tmp;
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retval = spi_setup(spi);
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if (retval < 0)
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spi->mode = save;
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else
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dev_dbg(&spi->dev, "spi mode %02x\n", tmp);
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}
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break;
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case SPI_IOC_WR_LSB_FIRST:
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retval = __get_user(tmp, (__u8 __user *)arg);
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if (retval == 0) {
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u8 save = spi->mode;
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if (tmp)
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spi->mode |= SPI_LSB_FIRST;
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else
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spi->mode &= ~SPI_LSB_FIRST;
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retval = spi_setup(spi);
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if (retval < 0)
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spi->mode = save;
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else
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dev_dbg(&spi->dev, "%csb first\n",
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tmp ? 'l' : 'm');
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}
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break;
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case SPI_IOC_WR_BITS_PER_WORD:
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retval = __get_user(tmp, (__u8 __user *)arg);
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if (retval == 0) {
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u8 save = spi->bits_per_word;
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spi->bits_per_word = tmp;
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retval = spi_setup(spi);
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if (retval < 0)
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spi->bits_per_word = save;
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else
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dev_dbg(&spi->dev, "%d bits per word\n", tmp);
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}
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break;
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case SPI_IOC_WR_MAX_SPEED_HZ:
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retval = __get_user(tmp, (__u32 __user *)arg);
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if (retval == 0) {
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u32 save = spi->max_speed_hz;
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spi->max_speed_hz = tmp;
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retval = spi_setup(spi);
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if (retval < 0)
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spi->max_speed_hz = save;
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else
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dev_dbg(&spi->dev, "%d Hz (max)\n", tmp);
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}
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break;
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default:
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/* segmented and/or full-duplex I/O request */
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if (_IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0))
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|| _IOC_DIR(cmd) != _IOC_WRITE) {
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retval = -ENOTTY;
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break;
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}
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tmp = _IOC_SIZE(cmd);
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if ((tmp % sizeof(struct spi_ioc_transfer)) != 0) {
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retval = -EINVAL;
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break;
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}
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n_ioc = tmp / sizeof(struct spi_ioc_transfer);
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if (n_ioc == 0)
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break;
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/* copy into scratch area */
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ioc = kmalloc(tmp, GFP_KERNEL);
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if (!ioc) {
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retval = -ENOMEM;
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break;
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}
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if (__copy_from_user(ioc, (void __user *)arg, tmp)) {
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kfree(ioc);
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retval = -EFAULT;
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break;
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}
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/* translate to spi_message, execute */
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retval = spidev_message(spidev, ioc, n_ioc);
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kfree(ioc);
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break;
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}
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mutex_unlock(&spidev->buf_lock);
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spi_dev_put(spi);
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return retval;
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}
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static int spidev_open(struct inode *inode, struct file *filp)
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{
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struct spidev_data *spidev;
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int status = -ENXIO;
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lock_kernel();
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mutex_lock(&device_list_lock);
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list_for_each_entry(spidev, &device_list, device_entry) {
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if (spidev->devt == inode->i_rdev) {
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status = 0;
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break;
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}
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}
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if (status == 0) {
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if (!spidev->buffer) {
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spidev->buffer = kmalloc(bufsiz, GFP_KERNEL);
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if (!spidev->buffer) {
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dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
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status = -ENOMEM;
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}
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}
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if (status == 0) {
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spidev->users++;
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filp->private_data = spidev;
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nonseekable_open(inode, filp);
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}
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} else
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pr_debug("spidev: nothing for minor %d\n", iminor(inode));
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mutex_unlock(&device_list_lock);
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unlock_kernel();
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return status;
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}
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static int spidev_release(struct inode *inode, struct file *filp)
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{
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struct spidev_data *spidev;
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int status = 0;
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mutex_lock(&device_list_lock);
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spidev = filp->private_data;
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filp->private_data = NULL;
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/* last close? */
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spidev->users--;
|
|
if (!spidev->users) {
|
|
int dofree;
|
|
|
|
kfree(spidev->buffer);
|
|
spidev->buffer = NULL;
|
|
|
|
/* ... 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 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,
|
|
.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 struct class *spidev_class;
|
|
|
|
/*-------------------------------------------------------------------------*/
|
|
|
|
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;
|
|
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 = IS_ERR(dev) ? PTR_ERR(dev) : 0;
|
|
} 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);
|
|
|
|
if (status != 0)
|
|
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;
|
|
spi_set_drvdata(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 = {
|
|
.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;
|
|
|
|
spidev_class = class_create(THIS_MODULE, "spidev");
|
|
if (IS_ERR(spidev_class)) {
|
|
unregister_chrdev(SPIDEV_MAJOR, spidev_spi.driver.name);
|
|
return PTR_ERR(spidev_class);
|
|
}
|
|
|
|
status = spi_register_driver(&spidev_spi);
|
|
if (status < 0) {
|
|
class_destroy(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_destroy(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");
|