diff options
Diffstat (limited to 'drivers/staging/comedi/comedi_fops.c')
| -rw-r--r-- | drivers/staging/comedi/comedi_fops.c | 90 |
1 files changed, 90 insertions, 0 deletions
diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c index 79b852c6d868..f143cb64d69e 100644 --- a/drivers/staging/comedi/comedi_fops.c +++ b/drivers/staging/comedi/comedi_fops.c @@ -1847,6 +1847,90 @@ static int do_poll_ioctl(struct comedi_device *dev, unsigned long arg, return -EINVAL; } +/* + * COMEDI_SETRSUBD ioctl + * sets the current "read" subdevice on a per-file basis + * + * arg: + * subdevice number + * + * reads: + * nothing + * + * writes: + * nothing + */ +static int do_setrsubd_ioctl(struct comedi_device *dev, unsigned long arg, + struct file *file) +{ + struct comedi_file *cfp = file->private_data; + struct comedi_subdevice *s_old, *s_new; + + if (arg >= dev->n_subdevices) + return -EINVAL; + + s_new = &dev->subdevices[arg]; + s_old = comedi_file_read_subdevice(file); + if (s_old == s_new) + return 0; /* no change */ + + if (!(s_new->subdev_flags & SDF_CMD_READ)) + return -EINVAL; + + /* + * Check the file isn't still busy handling a "read" command on the + * old subdevice (if any). + */ + if (s_old && s_old->busy == file && s_old->async && + !(s_old->async->cmd.flags & CMDF_WRITE)) + return -EBUSY; + + ACCESS_ONCE(cfp->read_subdev) = s_new; + return 0; +} + +/* + * COMEDI_SETWSUBD ioctl + * sets the current "write" subdevice on a per-file basis + * + * arg: + * subdevice number + * + * reads: + * nothing + * + * writes: + * nothing + */ +static int do_setwsubd_ioctl(struct comedi_device *dev, unsigned long arg, + struct file *file) +{ + struct comedi_file *cfp = file->private_data; + struct comedi_subdevice *s_old, *s_new; + + if (arg >= dev->n_subdevices) + return -EINVAL; + + s_new = &dev->subdevices[arg]; + s_old = comedi_file_write_subdevice(file); + if (s_old == s_new) + return 0; /* no change */ + + if (!(s_new->subdev_flags & SDF_CMD_WRITE)) + return -EINVAL; + + /* + * Check the file isn't still busy handling a "write" command on the + * old subdevice (if any). + */ + if (s_old && s_old->busy == file && s_old->async && + (s_old->async->cmd.flags & CMDF_WRITE)) + return -EBUSY; + + ACCESS_ONCE(cfp->write_subdev) = s_new; + return 0; +} + static long comedi_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { @@ -1941,6 +2025,12 @@ static long comedi_unlocked_ioctl(struct file *file, unsigned int cmd, case COMEDI_POLL: rc = do_poll_ioctl(dev, arg, file); break; + case COMEDI_SETRSUBD: + rc = do_setrsubd_ioctl(dev, arg, file); + break; + case COMEDI_SETWSUBD: + rc = do_setwsubd_ioctl(dev, arg, file); + break; default: rc = -ENOTTY; break; |