diff options
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/spi/spidev.c | 102 |
1 files changed, 89 insertions, 13 deletions
diff --git a/drivers/spi/spidev.c b/drivers/spi/spidev.c index b3518ca..41620c0 100644 --- a/drivers/spi/spidev.c +++ b/drivers/spi/spidev.c @@ -68,6 +68,7 @@ static unsigned long minors[N_SPI_MINORS / BITS_PER_LONG]; struct spidev_data { struct device dev; + spinlock_t spi_lock; struct spi_device *spi; struct list_head device_entry; @@ -85,12 +86,75 @@ MODULE_PARM_DESC(bufsiz, "data bytes in biggest supported SPI message"); /*-------------------------------------------------------------------------*/ +/* + * 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 */ @@ -98,10 +162,9 @@ spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos) return -EMSGSIZE; spidev = filp->private_data; - spi = spidev->spi; mutex_lock(&spidev->buf_lock); - status = spi_read(spi, spidev->buffer, count); + status = spidev_sync_read(spidev, count); if (status == 0) { unsigned long missing; @@ -122,7 +185,6 @@ 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; @@ -131,12 +193,11 @@ spidev_write(struct file *filp, const char __user *buf, 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); + status = spidev_sync_write(spidev, count); if (status == 0) status = count; } else @@ -153,7 +214,6 @@ static int spidev_message(struct spidev_data *spidev, 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; @@ -215,7 +275,7 @@ static int spidev_message(struct spidev_data *spidev, spi_message_add_tail(k_tmp, &msg); } - status = spi_sync(spi, &msg); + status = spidev_sync(spidev, &msg); if (status < 0) goto done; @@ -269,8 +329,16 @@ spidev_ioctl(struct inode *inode, struct file *filp, 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; switch (cmd) { /* read requests */ @@ -356,8 +424,10 @@ spidev_ioctl(struct inode *inode, struct file *filp, 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) { @@ -385,6 +455,7 @@ spidev_ioctl(struct inode *inode, struct file *filp, kfree(ioc); break; } + spi_dev_put(spi); return retval; } @@ -488,6 +559,7 @@ static int spidev_probe(struct spi_device *spi) /* Initialize the driver data */ spidev->spi = spi; + spin_lock_init(&spidev->spi_lock); mutex_init(&spidev->buf_lock); INIT_LIST_HEAD(&spidev->device_entry); @@ -526,13 +598,17 @@ static int spidev_remove(struct spi_device *spi) { struct spidev_data *spidev = dev_get_drvdata(&spi->dev); - mutex_lock(&device_list_lock); + /* make sure ops on existing fds can abort cleanly */ + spin_lock_irq(&spidev->spi_lock); + spidev->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); - mutex_unlock(&device_list_lock); return 0; |