[SCSI] add scsi changer driver

This patch adds a device driver for scsi media changer devices.
Signed-off-by: NGerd Knorr <kraxel@bytesex.org>
Signed-off-by: NJames Bottomley <James.Bottomley@SteelEye.com>

Documentation/scsi/scsi-changer.txt

+
+README for the SCSI media changer driver
+========================================
+
+This is a driver for SCSI Medium Changer devices, which are listed
+with "Type: Medium Changer" in /proc/scsi/scsi.
+
+This is for *real* Jukeboxes.  It is *not* supported to work with
+common small CD-ROM changers, neither one-lun-per-slot SCSI changers
+nor IDE drives.
+
+Userland tools available from here:
+	http://linux.bytesex.org/misc/changer.html
+
+
+General Information
+-------------------
+
+First some words about how changers work: A changer has 2 (possibly
+more) SCSI ID's. One for the changer device which controls the robot,
+and one for the device which actually reads and writes the data. The
+later may be anything, a MOD, a CD-ROM, a tape or whatever. For the
+changer device this is a "don't care", he *only* shuffles around the
+media, nothing else.
+
+
+The SCSI changer model is complex, compared to - for example - IDE-CD
+changers. But it allows to handle nearly all possible cases. It knows
+4 different types of changer elements:
+
+  media transport - this one shuffles around the media, i.e. the
+                    transport arm.  Also known as "picker".
+  storage         - a slot which can hold a media.
+  import/export   - the same as above, but is accessable from outside,
+                    i.e. there the operator (you !) can use this to
+                    fill in and remove media from the changer.
+		    Sometimes named "mailslot".
+  data transfer   - this is the device which reads/writes, i.e. the
+		    CD-ROM / Tape / whatever drive.
+
+None of these is limited to one: A huge Jukebox could have slots for
+123 CD-ROM's, 5 CD-ROM readers (and therefore 6 SCSI ID's: the changer
+and each CD-ROM) and 2 transport arms. No problem to handle.
+
+
+How it is implemented
+---------------------
+
+I implemented the driver as character device driver with a NetBSD-like
+ioctl interface. Just grabbed NetBSD's header file and one of the
+other linux SCSI device drivers as starting point. The interface
+should be source code compatible with NetBSD. So if there is any
+software (anybody knows ???) which supports a BSDish changer driver,
+it should work with this driver too.
+
+Over time a few more ioctls where added, volume tag support for example
+wasn't covered by the NetBSD ioctl API.
+
+
+Current State
+-------------
+
+Support for more than one transport arm is not implemented yet (and
+nobody asked for it so far...).
+
+I test and use the driver myself with a 35 slot cdrom jukebox from
+Grundig.  I got some reports telling it works ok with tape autoloaders
+(Exabyte, HP and DEC).  Some People use this driver with amanda.  It
+works fine with small (11 slots) and a huge (4 MOs, 88 slots)
+magneto-optical Jukebox.  Probably with lots of other changers too, most
+(but not all :-) people mail me only if it does *not* work...
+
+I don't have any device lists, neither black-list nor white-list.  Thus
+it is quite useless to ask me whenever a specific device is supported or
+not.  In theory every changer device which supports the SCSI-2 media
+changer command set should work out-of-the-box with this driver.  If it
+doesn't, it is a bug.  Either within the driver or within the firmware
+of the changer device.
+
+
+Using it
+--------
+
+This is a character device with major number is 86, so use
+"mknod /dev/sch0 c 86 0" to create the special file for the driver.
+
+If the module finds the changer, it prints some messages about the
+device [ try "dmesg" if you don't see anything ] and should show up in
+/proc/devices. If not....  some changers use ID ? / LUN 0 for the
+device and ID ? / LUN 1 for the robot mechanism. But Linux does *not*
+look for LUN's other than 0 as default, becauce there are to many
+broken devices. So you can try:
+
+  1) echo "scsi add-single-device 0 0 ID 1" > /proc/scsi/scsi
+     (replace ID with the SCSI-ID of the device)
+  2) boot the kernel with "max_scsi_luns=1" on the command line
+     (append="max_scsi_luns=1" in lilo.conf should do the trick)
+
+
+Trouble?
+--------
+
+If you insmod the driver with "insmod debug=1", it will be verbose and
+prints a lot of stuff to the syslog.  Compiling the kernel with
+CONFIG_SCSI_CONSTANTS=y improves the quality of the error messages alot
+because the kernel will translate the error codes into human-readable
+strings then.
+
+You can display these messages with the dmesg command (or check the
+logfiles).  If you email me some question becauce of a problem with the
+driver, please include these messages.
+
+
+Insmod options
+--------------
+
+debug=0/1
+	Enable debug messages (see above, default: 0).
+
+verbose=0/1
+	Be verbose (default: 1).
+
+init=0/1
+	Send INITIALIZE ELEMENT STATUS command to the changer
+	at insmod time (default: 1).
+
+timeout_init=<seconds>
+	timeout for the INITIALIZE ELEMENT STATUS command
+	(default: 3600).
+
+timeout_move=<seconds>
+	timeout for all other commands (default: 120).
+
+dt_id=<id1>,<id2>,...
+dt_lun=<lun1>,<lun2>,...
+	These two allow to specify the SCSI ID and LUN for the data
+	transfer elements.  You likely don't need this as the jukebox
+	should provide this information.  But some devices don't ...
+
+vendor_firsts=
+vendor_counts=
+vendor_labels=
+	These insmod options can be used to tell the driver that there
+	are some vendor-specific element types.  Grundig for example
+	does this.  Some jukeboxes have a printer to label fresh burned
+	CDs, which is addressed as element 0xc000 (type 5).  To tell the
+	driver about this vendor-specific element, use this:
+		$ insmod ch			\
+			vendor_firsts=0xc000	\
+			vendor_counts=1		\
+			vendor_labels=printer
+	All three insmod options accept up to four comma-separated
+	values, this way you can configure the element types 5-8.
+	You likely need the SCSI specs for the device in question to
+	find the correct values as they are not covered by the SCSI-2
+	standard.
+
+
+Credits
+-------
+
+I wrote this driver using the famous mailing-patches-around-the-world
+method.  With (more or less) help from:
+
+	Daniel Moehwald <moehwald@hdg.de>
+	Dane Jasper <dane@sonic.net>
+	R. Scott Bailey <sbailey@dsddi.eds.com>
+	Jonathan Corbet <corbet@lwn.net>
+
+Special thanks go to
+	Martin Kuehne <martin.kuehne@bnbt.de>
+for a old, second-hand (but full functional) cdrom jukebox which I use
+to develop/test driver and tools now.
+
+Have fun,
+
+   Gerd
+
+-- 
+Gerd Knorr <kraxel@bytesex.org>

drivers/scsi/Kconfig

@@ -137,6 +137,24 @@ config CHR_DEV_SG
 
 	  If unsure, say N.
 
+config CHR_DEV_SCH
+	tristate "SCSI media changer support"
+	depends on SCSI
+	---help---
+	  This is a driver for SCSI media changers.  Most common devices are
+	  tape libraries and MOD/CDROM jukeboxes.  *Real* jukeboxes, you
+	  don't need this for those tiny 6-slot cdrom changers.  Media
+	  changers are listed as "Type: Medium Changer" in /proc/scsi/scsi.
+	  If you have such hardware and want to use it with linux, say Y
+	  here.  Check <file:Documentation/scsi-changer.txt> for details.
+	
+	  If you want to compile this as a module ( = code which can be
+	  inserted in and removed from the running kernel whenever you want),
+	  say M here and read <file:Documentation/modules.txt> and
+	  <file:Documentation/scsi.txt>. The module will be called ch.o.
+	  If unsure, say N.
+	
+
 comment "Some SCSI devices (e.g. CD jukebox) support multiple LUNs"
 	depends on SCSI
 

drivers/scsi/Makefile

@@ -140,6 +140,7 @@ obj-$(CONFIG_CHR_DEV_OSST)	+= osst.o
 obj-$(CONFIG_BLK_DEV_SD)	+= sd_mod.o
 obj-$(CONFIG_BLK_DEV_SR)	+= sr_mod.o
 obj-$(CONFIG_CHR_DEV_SG)	+= sg.o
+obj-$(CONFIG_CHR_DEV_SCH)	+= ch.o
 
 scsi_mod-y			+= scsi.o hosts.o scsi_ioctl.o constants.o \
 				   scsicam.o scsi_error.o scsi_lib.o \

include/linux/chio.h

+/*
+ * ioctl interface for the scsi media changer driver
+ */
+
+/* changer element types */
+#define CHET_MT   0	/* media transport element (robot) */
+#define CHET_ST   1	/* storage element (media slots) */
+#define CHET_IE   2	/* import/export element */
+#define CHET_DT   3	/* data transfer element (tape/cdrom/whatever) */
+#define CHET_V1   4	/* vendor specific #1 */
+#define CHET_V2   5	/* vendor specific #2 */
+#define CHET_V3   6	/* vendor specific #3 */
+#define CHET_V4   7	/* vendor specific #4 */
+
+
+/*
+ * CHIOGPARAMS
+ *    query changer properties
+ *
+ * CHIOVGPARAMS
+ *    query vendor-specific element types
+ *
+ *    accessing elements works by specifing type and unit of the element.
+ *    for eample, storage elements are addressed with type = CHET_ST and
+ *    unit = 0 .. cp_nslots-1
+ *
+ */
+struct changer_params {
+	int cp_curpicker;  /* current transport element */
+	int cp_npickers;   /* number of transport elements      (CHET_MT) */
+	int cp_nslots;     /* number of storage elements        (CHET_ST) */
+	int cp_nportals;   /* number of import/export elements  (CHET_IE) */
+	int cp_ndrives;    /* number of data transfer elements  (CHET_DT) */
+};
+struct changer_vendor_params {
+	int  cvp_n1;       /* number of vendor specific elems   (CHET_V1) */
+	char cvp_label1[16];
+	int  cvp_n2;       /* number of vendor specific elems   (CHET_V2) */
+	char cvp_label2[16];
+	int  cvp_n3;       /* number of vendor specific elems   (CHET_V3) */
+	char cvp_label3[16];
+	int  cvp_n4;       /* number of vendor specific elems   (CHET_V4) */
+	char cvp_label4[16];
+	int  reserved[8];
+};
+
+
+/*
+ * CHIOMOVE
+ *    move a medium from one element to another
+ */
+struct changer_move {
+	int cm_fromtype;	/* type/unit of source element */
+	int cm_fromunit;	
+	int cm_totype;	/* type/unit of destination element */
+	int cm_tounit;
+	int cm_flags;
+};
+#define CM_INVERT   1   /* flag: rotate media (for double-sided like MOD) */
+
+
+/*
+ * CHIOEXCHANGE
+ *    move one medium from element #1 to element #2,
+ *    and another one from element #2 to element #3.
+ *    element #1 and #3 are allowed to be identical.
+ */
+struct changer_exchange {
+	int ce_srctype;	    /* type/unit of element #1 */
+	int ce_srcunit;
+	int ce_fdsttype;    /* type/unit of element #2 */
+	int ce_fdstunit;
+	int ce_sdsttype;    /* type/unit of element #3 */
+	int ce_sdstunit;
+	int ce_flags;
+};
+#define CE_INVERT1   1
+#define CE_INVERT2   2
+
+
+/*
+ * CHIOPOSITION
+ *    move the transport element (robot arm) to a specific element.
+ */
+struct changer_position {
+	int cp_type;
+	int cp_unit;
+	int cp_flags;
+};
+#define CP_INVERT   1
+
+
+/*
+ * CHIOGSTATUS
+ *    get element status for all elements of a specific type
+ */
+struct changer_element_status {
+	int             ces_type;
+	unsigned char   *ces_data;
+};
+#define CESTATUS_FULL     0x01 /* full */
+#define CESTATUS_IMPEXP   0x02	/* media was imported (inserted by sysop) */
+#define CESTATUS_EXCEPT   0x04	/* error condition */
+#define CESTATUS_ACCESS   0x08	/* access allowed */
+#define CESTATUS_EXENAB   0x10	/* element can export media */
+#define CESTATUS_INENAB   0x20	/* element can import media */
+
+
+/*
+ * CHIOGELEM
+ *    get more detailed status informtion for a single element
+ */
+struct changer_get_element {
+	int	cge_type;	 /* type/unit */
+	int	cge_unit;
+	int	cge_status;      /* status */
+	int     cge_errno;       /* errno */
+	int     cge_srctype;     /* source element of the last move/exchange */
+	int     cge_srcunit;
+	int     cge_id;          /* scsi id  (for data transfer elements) */
+	int     cge_lun;         /* scsi lun (for data transfer elements) */
+	char    cge_pvoltag[36]; /* primary volume tag */
+	char    cge_avoltag[36]; /* alternate volume tag */
+	int     cge_flags;
+};
+/* flags */
+#define CGE_ERRNO     0x01       /* errno available       */
+#define CGE_INVERT    0x02       /* media inverted        */
+#define CGE_SRC       0x04       /* media src available   */
+#define CGE_IDLUN     0x08       /* ID+LUN available      */
+#define CGE_PVOLTAG   0x10       /* primary volume tag available */
+#define CGE_AVOLTAG   0x20       /* alternate volume tag available */
+
+
+/*
+ * CHIOSVOLTAG
+ *    set volume tag
+ */
+struct changer_set_voltag {
+	int	csv_type;	 /* type/unit */
+	int	csv_unit;
+	char    csv_voltag[36];  /* volume tag */
+	int     csv_flags;
+};
+#define CSV_PVOLTAG   0x01       /* primary volume tag */
+#define CSV_AVOLTAG   0x02       /* alternate volume tag */
+#define CSV_CLEARTAG  0x04       /* clear volume tag */
+
+/* ioctls */
+#define CHIOMOVE       _IOW('c', 1,struct changer_move)
+#define CHIOEXCHANGE   _IOW('c', 2,struct changer_exchange)
+#define CHIOPOSITION   _IOW('c', 3,struct changer_position)
+#define CHIOGPICKER    _IOR('c', 4,int)                        /* not impl. */
+#define CHIOSPICKER    _IOW('c', 5,int)                        /* not impl. */
+#define CHIOGPARAMS    _IOR('c', 6,struct changer_params)
+#define CHIOGSTATUS    _IOW('c', 8,struct changer_element_status)
+#define CHIOGELEM      _IOW('c',16,struct changer_get_element)
+#define CHIOINITELEM   _IO('c',17)
+#define CHIOSVOLTAG    _IOW('c',18,struct changer_set_voltag)
+#define CHIOGVPARAMS   _IOR('c',19,struct changer_vendor_params)
+
+/* ---------------------------------------------------------------------- */
+
+/*
+ * Local variables:
+ * c-basic-offset: 8
+ * End:
+ */

include/linux/major.h

@@ -100,6 +100,7 @@
 #define I2O_MAJOR		80	/* 80->87 */
 
 #define SHMIQ_MAJOR		85   /* Linux/mips, SGI /dev/shmiq */
+#define SCSI_CHANGER_MAJOR      86
 
 #define IDE6_MAJOR		88
 #define IDE7_MAJOR		89

include/scsi/scsi.h

@@ -41,6 +41,7 @@ extern const char *const scsi_device_types[MAX_SCSI_DEVICE_CODE];
 #define FORMAT_UNIT           0x04
 #define READ_BLOCK_LIMITS     0x05
 #define REASSIGN_BLOCKS       0x07
+#define INITIALIZE_ELEMENT_STATUS 0x07
 #define READ_6                0x08
 #define WRITE_6               0x0a
 #define SEEK_6                0x0b
@@ -65,6 +66,7 @@ extern const char *const scsi_device_types[MAX_SCSI_DEVICE_CODE];
 #define READ_10               0x28
 #define WRITE_10              0x2a
 #define SEEK_10               0x2b
+#define POSITION_TO_ELEMENT   0x2b
 #define WRITE_VERIFY          0x2e
 #define VERIFY                0x2f
 #define SEARCH_HIGH           0x30
@@ -97,6 +99,7 @@ extern const char *const scsi_device_types[MAX_SCSI_DEVICE_CODE];
 #define PERSISTENT_RESERVE_OUT 0x5f
 #define REPORT_LUNS           0xa0
 #define MOVE_MEDIUM           0xa5
+#define EXCHANGE_MEDIUM       0xa6
 #define READ_12               0xa8
 #define WRITE_12              0xaa
 #define WRITE_VERIFY_12       0xae