#include <linux/ioctl.h>
#include <linux/fs.h>
#include <linux/device.h>
+#include <linux/err.h>
#include <linux/list.h>
#include <linux/errno.h>
#include <linux/mutex.h>
* 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
+ * transfers. There are several kinds of internal message boundaries to
* handle chipselect management and other protocol options.
*
* SPI has a character major number assigned. We allocate minor numbers
/* Bit masks for spi_device.mode management. Note that incorrect
- * settings for CS_HIGH and 3WIRE can cause *lots* of trouble for other
- * devices on a shared bus: CS_HIGH, because this device will be
- * active when it shouldn't be; 3WIRE, because when active it won't
- * behave as it should.
+ * settings for some settings can cause *lots* of trouble for other
+ * devices on a shared bus:
*
- * REVISIT should changing those two modes be privileged?
+ * - CS_HIGH ... this device will be active when it shouldn't be
+ * - 3WIRE ... when active, it won't behave as it should
+ * - NO_CS ... there will be no explicit message boundaries; this
+ * is completely incompatible with the shared bus model
+ * - READY ... transfers may proceed when they shouldn't.
+ *
+ * REVISIT should changing those flags be privileged?
*/
#define SPI_MODE_MASK (SPI_CPHA | SPI_CPOL | SPI_CS_HIGH \
- | SPI_LSB_FIRST | SPI_3WIRE | SPI_LOOP)
+ | SPI_LSB_FIRST | SPI_3WIRE | SPI_LOOP \
+ | SPI_NO_CS | SPI_READY)
struct spidev_data {
- struct device dev;
+ dev_t devt;
+ spinlock_t spi_lock;
struct spi_device *spi;
struct list_head device_entry;
+ /* buffer is NULL unless this device is open (users > 0) */
struct mutex buf_lock;
unsigned users;
u8 *buffer;
/*-------------------------------------------------------------------------*/
+/*
+ * We can't use the standard synchronous wrappers for file I/O; we
+ * need to protect against async removal of the underlying spi_device.
+ */
+static void spidev_complete(void *arg)
+{
+ complete(arg);
+}
+
+static ssize_t
+spidev_sync(struct spidev_data *spidev, struct spi_message *message)
+{
+ DECLARE_COMPLETION_ONSTACK(done);
+ int status;
+
+ message->complete = spidev_complete;
+ message->context = &done;
+
+ spin_lock_irq(&spidev->spi_lock);
+ if (spidev->spi == NULL)
+ status = -ESHUTDOWN;
+ else
+ status = spi_async(spidev->spi, message);
+ spin_unlock_irq(&spidev->spi_lock);
+
+ if (status == 0) {
+ wait_for_completion(&done);
+ status = message->status;
+ if (status == 0)
+ status = message->actual_length;
+ }
+ return status;
+}
+
+static inline ssize_t
+spidev_sync_write(struct spidev_data *spidev, size_t len)
+{
+ struct spi_transfer t = {
+ .tx_buf = spidev->buffer,
+ .len = len,
+ };
+ struct spi_message m;
+
+ spi_message_init(&m);
+ spi_message_add_tail(&t, &m);
+ return spidev_sync(spidev, &m);
+}
+
+static inline ssize_t
+spidev_sync_read(struct spidev_data *spidev, size_t len)
+{
+ struct spi_transfer t = {
+ .rx_buf = spidev->buffer,
+ .len = len,
+ };
+ struct spi_message m;
+
+ spi_message_init(&m);
+ spi_message_add_tail(&t, &m);
+ return spidev_sync(spidev, &m);
+}
+
+/*-------------------------------------------------------------------------*/
+
/* Read-only message with current device setup */
static ssize_t
spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
{
struct spidev_data *spidev;
- struct spi_device *spi;
ssize_t status = 0;
/* chipselect only toggles at start or end of operation */
return -EMSGSIZE;
spidev = filp->private_data;
- spi = spidev->spi;
mutex_lock(&spidev->buf_lock);
- status = spi_read(spi, spidev->buffer, count);
- if (status == 0) {
+ status = spidev_sync_read(spidev, count);
+ if (status > 0) {
unsigned long missing;
- missing = copy_to_user(buf, spidev->buffer, count);
- if (count && missing == count)
+ missing = copy_to_user(buf, spidev->buffer, status);
+ if (missing == status)
status = -EFAULT;
else
- status = count - missing;
+ status = status - missing;
}
mutex_unlock(&spidev->buf_lock);
size_t count, loff_t *f_pos)
{
struct spidev_data *spidev;
- struct spi_device *spi;
ssize_t status = 0;
unsigned long missing;
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;
+ status = spidev_sync_write(spidev, count);
} else
status = -EFAULT;
mutex_unlock(&spidev->buf_lock);
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;
* 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;
k_tmp->delay_usecs = u_tmp->delay_usecs;
k_tmp->speed_hz = u_tmp->speed_hz;
#ifdef VERBOSE
- dev_dbg(&spi->dev,
+ dev_dbg(&spidev->spi->dev,
" xfer len %zd %s%s%s%dbits %u usec %uHz\n",
u_tmp->len,
u_tmp->rx_buf ? "rx " : "",
u_tmp->tx_buf ? "tx " : "",
u_tmp->cs_change ? "cs " : "",
- u_tmp->bits_per_word ? : spi->bits_per_word,
+ u_tmp->bits_per_word ? : spidev->spi->bits_per_word,
u_tmp->delay_usecs,
- u_tmp->speed_hz ? : spi->max_speed_hz);
+ u_tmp->speed_hz ? : spidev->spi->max_speed_hz);
#endif
spi_message_add_tail(k_tmp, &msg);
}
- status = spi_sync(spi, &msg);
+ status = spidev_sync(spidev, &msg);
if (status < 0)
goto done;
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)
+static long
+spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
int err = 0;
int retval = 0;
if (err)
return -EFAULT;
+ /* guard against device removal before, or while,
+ * we issue this ioctl.
+ */
spidev = filp->private_data;
- spi = spidev->spi;
+ spin_lock_irq(&spidev->spi_lock);
+ spi = spi_dev_get(spidev->spi);
+ spin_unlock_irq(&spidev->spi_lock);
+
+ if (spi == NULL)
+ return -ESHUTDOWN;
+
+ /* use the buffer lock here for triple duty:
+ * - prevent I/O (from us) so calling spi_setup() is safe;
+ * - prevent concurrent SPI_IOC_WR_* from morphing
+ * data fields while SPI_IOC_RD_* reads them;
+ * - SPI_IOC_MESSAGE needs the buffer locked "normally".
+ */
+ mutex_lock(&spidev->buf_lock);
switch (cmd) {
/* read requests */
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;
+ || _IOC_DIR(cmd) != _IOC_WRITE) {
+ retval = -ENOTTY;
+ break;
+ }
tmp = _IOC_SIZE(cmd);
if ((tmp % sizeof(struct spi_ioc_transfer)) != 0) {
kfree(ioc);
break;
}
+
+ mutex_unlock(&spidev->buf_lock);
+ spi_dev_put(spi);
return retval;
}
mutex_lock(&device_list_lock);
list_for_each_entry(spidev, &device_list, device_entry) {
- if (spidev->dev.devt == inode->i_rdev) {
+ if (spidev->devt == inode->i_rdev) {
status = 0;
break;
}
mutex_lock(&device_list_lock);
spidev = filp->private_data;
filp->private_data = NULL;
+
+ /* last close? */
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 = {
+static const struct file_operations spidev_fops = {
.owner = THIS_MODULE,
/* REVISIT switch to aio primitives, so that userspace
* gets more complete API coverage. It'll simplify things
*/
.write = spidev_write,
.read = spidev_read,
- .ioctl = spidev_ioctl,
+ .unlocked_ioctl = spidev_ioctl,
.open = spidev_open,
.release = spidev_release,
};
* 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 struct class *spidev_class;
/*-------------------------------------------------------------------------*/
/* Initialize the driver data */
spidev->spi = spi;
+ spin_lock_init(&spidev->spi_lock);
mutex_init(&spidev->buf_lock);
INIT_LIST_HEAD(&spidev->device_entry);
mutex_lock(&device_list_lock);
minor = find_first_zero_bit(minors, N_SPI_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);
+ 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);
- dev_set_drvdata(&spi->dev, spidev);
list_add(&spidev->device_entry, &device_list);
}
mutex_unlock(&device_list_lock);
- if (status != 0)
+ if (status == 0)
+ spi_set_drvdata(spi, spidev);
+ else
kfree(spidev);
return status;
static int spidev_remove(struct spi_device *spi)
{
- struct spidev_data *spidev = dev_get_drvdata(&spi->dev);
+ struct spidev_data *spidev = spi_get_drvdata(spi);
- mutex_lock(&device_list_lock);
+ /* 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);
- dev_set_drvdata(&spi->dev, NULL);
- clear_bit(MINOR(spidev->dev.devt), minors);
- device_unregister(&spidev->dev);
-
+ 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;
if (status < 0)
return status;
- status = class_register(&spidev_class);
- if (status < 0) {
+ spidev_class = class_create(THIS_MODULE, "spidev");
+ if (IS_ERR(spidev_class)) {
unregister_chrdev(SPIDEV_MAJOR, spidev_spi.driver.name);
- return status;
+ return PTR_ERR(spidev_class);
}
status = spi_register_driver(&spidev_spi);
if (status < 0) {
- class_unregister(&spidev_class);
+ class_destroy(spidev_class);
unregister_chrdev(SPIDEV_MAJOR, spidev_spi.driver.name);
}
return status;
static void __exit spidev_exit(void)
{
spi_unregister_driver(&spidev_spi);
- class_unregister(&spidev_class);
+ 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");
+MODULE_ALIAS("spi:spidev");
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff