diff options
Diffstat (limited to 'Documentation/cdrom/cdrom-standard.rst')
| -rw-r--r-- | Documentation/cdrom/cdrom-standard.rst | 73 |
1 files changed, 29 insertions, 44 deletions
diff --git a/Documentation/cdrom/cdrom-standard.rst b/Documentation/cdrom/cdrom-standard.rst index dde4f7f7fdbf..7964fe134277 100644 --- a/Documentation/cdrom/cdrom-standard.rst +++ b/Documentation/cdrom/cdrom-standard.rst @@ -146,19 +146,18 @@ with the kernel as a block device by registering the following general *struct file_operations*:: struct file_operations cdrom_fops = { - NULL, /∗ lseek ∗/ - block _read , /∗ read—general block-dev read ∗/ - block _write, /∗ write—general block-dev write ∗/ - NULL, /∗ readdir ∗/ - NULL, /∗ select ∗/ - cdrom_ioctl, /∗ ioctl ∗/ - NULL, /∗ mmap ∗/ - cdrom_open, /∗ open ∗/ - cdrom_release, /∗ release ∗/ - NULL, /∗ fsync ∗/ - NULL, /∗ fasync ∗/ - cdrom_media_changed, /∗ media change ∗/ - NULL /∗ revalidate ∗/ + NULL, /* lseek */ + block _read , /* read--general block-dev read */ + block _write, /* write--general block-dev write */ + NULL, /* readdir */ + NULL, /* select */ + cdrom_ioctl, /* ioctl */ + NULL, /* mmap */ + cdrom_open, /* open */ + cdrom_release, /* release */ + NULL, /* fsync */ + NULL, /* fasync */ + NULL /* revalidate */ }; Every active CD-ROM device shares this *struct*. The routines @@ -219,7 +218,6 @@ current *struct* is:: int (*tray_move)(struct cdrom_device_info *, int); int (*lock_door)(struct cdrom_device_info *, int); int (*select_speed)(struct cdrom_device_info *, int); - int (*select_disc)(struct cdrom_device_info *, int); int (*get_last_session) (struct cdrom_device_info *, struct cdrom_multisession *); int (*get_mcn)(struct cdrom_device_info *, struct cdrom_mcn *); @@ -251,12 +249,12 @@ The drive-specific, minor-like information that is registered with `cdrom.c`, currently contains the following fields:: struct cdrom_device_info { - const struct cdrom_device_ops * ops; /* device operations for this major */ + const struct cdrom_device_ops * ops; /* device operations for this major */ struct list_head list; /* linked list of all device_info */ struct gendisk * disk; /* matching block layer disk */ void * handle; /* driver-dependent data */ - int mask; /* mask of capability: disables them */ + int mask; /* mask of capability: disables them */ int speed; /* maximum speed for reading data */ int capacity; /* number of discs in a jukebox */ @@ -368,19 +366,6 @@ which may or may not be in the drive). If the drive is not a changer, :: - int media_changed(struct cdrom_device_info *cdi, int disc_nr) - -This function is very similar to the original function in $struct -file_operations*. It returns 1 if the medium of the device *cdi->dev* -has changed since the last call, and 0 otherwise. The parameter -*disc_nr* identifies a specific slot in a juke-box, it should be -ignored for single-disc drives. Note that by `re-routing` this -function through *cdrom_media_changed()*, we can implement separate -queues for the VFS and a new *ioctl()* function that can report device -changes to software (e. g., an auto-mounting daemon). - -:: - int tray_move(struct cdrom_device_info *cdi, int position) This function, if implemented, should control the tray movement. (No @@ -435,15 +420,6 @@ return value indicates an error. :: - int select_disc(struct cdrom_device_info *cdi, int number) - -If the drive can store multiple discs (a juke-box) this function -will perform disc selection. It should return the number of the -selected disc on success, a negative value on error. Currently, only -the ide-cd driver supports this functionality. - -:: - int get_last_session(struct cdrom_device_info *cdi, struct cdrom_multisession *ms_info) @@ -571,7 +547,7 @@ phase. Currently, the capabilities are any of:: CDC_DRIVE_STATUS /* driver implements drive status */ The capability flag is declared *const*, to prevent drivers from -accidentally tampering with the contents. The capability fags actually +accidentally tampering with the contents. The capability flags actually inform `cdrom.c` of what the driver can do. If the drive found by the driver does not have the capability, is can be masked out by the *cdrom_device_info* variable *mask*. For instance, the SCSI CD-ROM @@ -583,7 +559,7 @@ the *CDC_CLOSE_TRAY* bit in *mask*. In the file `cdrom.c` you will encounter many constructions of the type:: - if (cdo->capability & ∼cdi->mask & CDC _⟨capability⟩) ... + if (cdo->capability & ~cdi->mask & CDC _<capability>) ... There is no *ioctl* to set the mask... The reason is that I think it is better to control the **behavior** rather than the @@ -750,7 +726,7 @@ Description of routines in `cdrom.c` Only a few routines in `cdrom.c` are exported to the drivers. In this new section we will discuss these, as well as the functions that `take -over' the CD-ROM interface to the kernel. The header file belonging +over` the CD-ROM interface to the kernel. The header file belonging to `cdrom.c` is called `cdrom.h`. Formerly, some of the contents of this file were placed in the file `ucdrom.h`, but this file has now been merged back into `cdrom.h`. @@ -917,12 +893,21 @@ commands can be identified by the underscores in their names. maximum number of discs in the juke-box found in the *cdrom_dops*. `CDROM_MEDIA_CHANGED` Returns 1 if a disc has been changed since the last call. - Note that calls to *cdrom_media_changed* by the VFS are treated - by an independent queue, so both mechanisms will detect a - media change once. For juke-boxes, an extra argument *arg* + For juke-boxes, an extra argument *arg* specifies the slot for which the information is given. The special value *CDSL_CURRENT* requests that information about the currently selected slot be returned. +`CDROM_TIMED_MEDIA_CHANGE` + Checks whether the disc has been changed since a user supplied time + and returns the time of the last disc change. + + *arg* is a pointer to a *cdrom_timed_media_change_info* struct. + *arg->last_media_change* may be set by calling code to signal + the timestamp of the last known media change (by the caller). + Upon successful return, this ioctl call will set + *arg->last_media_change* to the latest media change timestamp (in ms) + known by the kernel/driver and set *arg->has_changed* to 1 if + that timestamp is more recent than the timestamp set by the caller. `CDROM_DRIVE_STATUS` Returns the status of the drive by a call to *drive_status()*. Return values are defined in cdrom_drive_status_. |