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MICROSEQ(9)		 BSD Kernel Developer's	Manual		   MICROSEQ(9)

     microseq -- ppbus microseqencer developer's guide

     #include <sys/types.h>
     #include <dev/ppbus/ppbconf.h>
     #include <dev/ppbus/ppb_msq.h>

     See ppbus(4) for ppbus description	and general info about the microse-

     The purpose of this document is to	encourage developers to	use the	mi-
     crosequencer mechanism in order to	have:

	   1.	a uniform programming model

	   2.	efficient code

     Before using microsequences, you are encouraged to	look at	ppc(4) mi-
     crosequencer implementation and an	example	of how using it	in vpo(4).

PPBUS register model
     The parallel port model chosen for	ppbus is the PC	parallel port model.
     Thus, any register	described later	has the	same semantic than its coun-
     terpart in	a PC parallel port.  For more info about ISA/ECP programming,
     get the Microsoft standard	referenced as "Extended	Capabilities Port Pro-
     tocol and ISA interface Standard".	Registers described later are standard
     parallel port registers.

     Mask macros are defined in	the standard ppbus include files for each
     valid bit of parallel port	registers.

   Data	register
     In	compatible or nibble mode, writing to this register will drive data to
     the parallel port data lines.  In any other mode, drivers may be tri-
     stated by setting the direction bit (PCD) in the control register.	 Reads
     to	this register return the value on the data lines.

   Device status register
     This read-only register reflects the inputs on the	parallel port inter-

     Bit    Name    Description
     7	    nBUSY   inverted version of	parallel port Busy signal
     6	    nACK    version of parallel	port nAck signal
     5	    PERROR  version of parallel	port PERROR signal
     4	    SELECT  version of parallel	port Select signal
     3	    nFAULT  version of parallel	port nFault signal

     Others are	reserved and return undefined result when read.

   Device control register
     This register directly controls several output signals as well as en-
     abling some functions.

     Bit    Name	Description
     5	    PCD		direction bit in extended modes
     4	    IRQENABLE	1 enables an interrupt on the rising edge of nAck
     3	    SELECTIN	inverted and driven as parallel	port nSelectin signal
     2	    nINIT	driven as parallel port	nInit signal
     1	    AUTOFEED	inverted and driven as parallel	port nAutoFd signal
     0	    STROBE	inverted and driven as parallel	port nStrobe signal

     Microinstructions are either parallel port	accesses, program iterations,
     submicrosequence or C calls.  The parallel	port must be considered	as the
     logical model described in	ppbus(4).

     Available microinstructions are:

     #define MS_OP_GET	     0	     /*	get <ptr>, <len>		     */
     #define MS_OP_PUT	     1	     /*	put <ptr>, <len>		     */
     #define MS_OP_RFETCH    2	     /*	rfetch <reg>, <mask>, <ptr>	     */
     #define MS_OP_RSET	     3	     /*	rset <reg>, <mask>, <mask>	     */
     #define MS_OP_RASSERT   4	     /*	rassert	<reg>, <mask>		     */
     #define MS_OP_DELAY     5	     /*	delay <val>			     */
     #define MS_OP_SET	     6	     /*	set <val>			     */
     #define MS_OP_DBRA	     7	     /*	dbra <offset>			     */
     #define MS_OP_BRSET     8	     /*	brset <mask>, <offset>		     */
     #define MS_OP_BRCLEAR   9	     /*	brclear	<mask>,	<offset>	     */
     #define MS_OP_RET	     10	     /*	ret <retcode>			     */
     #define MS_OP_C_CALL    11	     /*	c_call <function>, <parameter>	     */
     #define MS_OP_PTR	     12	     /*	ptr <pointer>			     */
     #define MS_OP_ADELAY    13	     /*	adelay <val>			     */
     #define MS_OP_BRSTAT    14	     /*	brstat <mask>, <mask>, <offset>	     */
     #define MS_OP_SUBRET    15	     /*	subret <code>			     */
     #define MS_OP_CALL	     16	     /*	call <microsequence>		     */
     #define MS_OP_RASSERT_P 17	     /*	rassert_p <iter>, <reg>		     */
     #define MS_OP_RFETCH_P  18	     /*	rfetch_p <iter>, <reg>,	<mask>	     */
     #define MS_OP_TRIG	     19	     /*	trigger	<reg>, <len>, <array>	     */

   Execution context
     The execution context of microinstructions	is:

	   +o   the program counter which points	to the next microinstruction
	       to execute either in the	main microsequence or in a subcall

	   +o   the current value of ptr	which points to	the next char to

	   +o   the current value of the	internal branch	register

     This data is modified by some of the microinstructions, not all.

     are microinstructions used	to do either predefined	standard IEEE1284-1994
     transfers or programmed non-standard io.

   MS_OP_RFETCH	- Register FETCH
     is	used to	retrieve the current value of a	parallel port register,	apply
     a mask and	save it	in a buffer.


	   1.	register

	   2.	character mask

	   3.	pointer	to the buffer

     Predefined	macro: MS_RFETCH(reg,mask,ptr)

   MS_OP_RSET -	Register SET
     is	used to	assert/clear some bits of a particular parallel	port register,
     two masks are applied.


	   1.	register

	   2.	mask of	bits to	assert

	   3.	mask of	bits to	clear

     Predefined	macro: MS_RSET(reg,assert,clear)

     is	used to	assert all bits	of a particular	parallel port register.


	   1.	register

	   2.	byte to	assert

     Predefined	macro: MS_RASSERT(reg,byte)

   MS_OP_DELAY - microsecond DELAY
     is	used to	delay the execution of the microsequence.


	   1.	delay in microseconds

     Predefined	macro: MS_DELAY(delay)

   MS_OP_SET - SET internal branch register
     is	used to	set the	value of the internal branch register.


	   1.	integer	value

     Predefined	macro: MS_SET(accum)

   MS_OP_DBRA -	Do BRAnch
     is	used to	branch if internal branch register decremented by one result
     value is positive.


	   1.	integer	offset in the current executed (sub)microsequence.
		Offset is added	to the index of	the next microinstruction to

     Predefined	macro: MS_DBRA(offset)

   MS_OP_BRSET - BRanch	on SET
     is	used to	branch if some of the status register bits of the parallel
     port are set.


	   1.	bits of	the status register

	   2.	integer	offset in the current executed (sub)microsequence.
		Offset is added	to the index of	the next microinstruction to

     Predefined	macro: MS_BRSET(mask,offset)

     is	used to	branch if some of the status register bits of the parallel
     port are cleared.


	   1.	bits of	the status register

	   2.	integer	offset in the current executed (sub)microsequence.
		Offset is added	to the index of	the next microinstruction to

     Predefined	macro: MS_BRCLEAR(mask,offset)

   MS_OP_RET - RETurn
     is	used to	return from a microsequence.  This instruction is mandatory.
     This is the only way for the microsequencer to detect the end of the mi-
     crosequence.  The return code is returned in the integer pointed by the
     (int *) parameter of the ppb_MS_microseq().


	   1.	integer	return code

     Predefined	macro: MS_RET(code)

   MS_OP_C_CALL	- C function CALL
     is	used to	call C functions from microsequence execution.	This may be
     useful when a non-standard	i/o is performed to retrieve a data character
     from the parallel port.


	   1.	the C function to call

	   2.	the parameter to pass to the function call

     The C function shall be declared as a int(*)(void *p, char	*ptr).	The
     ptr parameter is the current position in the buffer currently scanned.

     Predefined	macro: MS_C_CALL(func,param)

   MS_OP_PTR - initialize internal PTR
     is	used to	initialize the internal	pointer	to the currently scanned buf-
     fer.  This	pointer	is passed to any C call	(see above).


	   1.	pointer	to the buffer that shall be accessed by	xxx_P()	mi-
		crosequence calls.  Note that this pointer is automatically
		incremented during xxx_P() calls

     Predefined	macro: MS_PTR(ptr)

   MS_OP_ADELAY	- do an	Asynchronous DELAY
     is	used to	make a tsleep()	during microsequence execution.	 The tsleep is
     executed at PPBPRI	level.


	   1.	delay in ms

     Predefined	macro: MS_ADELAY(delay)

   MS_OP_BRSTAT	- BRanch on STATe
     is	used to	branch on status register state	condition.


	   1.	mask of	asserted bits.	Bits that shall	be asserted in the
		status register	are set	in the mask

	   2.	mask of	cleared	bits.  Bits that shall be cleared in the sta-
		tus register are set in	the mask

	   3.	integer	offset in the current executed (sub)microsequence.
		Offset is added	to the index of	the next microinstruction to

     Predefined	macro: MS_BRSTAT(asserted_bits,clear_bits,offset)

   MS_OP_SUBRET	- SUBmicrosequence RETurn
     is	used to	return from the	submicrosequence call.	This action is manda-
     tory before a RET call.  Some microinstructions (PUT, GET)	may not	be
     callable within a submicrosequence.

     No	parameter.

     Predefined	macro: MS_SUBRET()

   MS_OP_CALL -	submicrosequence CALL
     is	used to	call a submicrosequence.  A submicrosequence is	a microse-
     quence with a SUBRET call.	 Parameter:

	   1.	the submicrosequence to	execute

     Predefined	macro: MS_CALL(microseq)

   MS_OP_RASSERT_P - Register ASSERT from internal PTR
     is	used to	assert a register with data currently pointed by the internal
     PTR pointer.  Parameter:

	   1.	amount of data to write	to the register

	   2.	register

     Predefined	macro: MS_RASSERT_P(iter,reg)

   MS_OP_RFETCH_P - Register FETCH to internal PTR
     is	used to	fetch data from	a register.  Data is stored in the buffer cur-
     rently pointed by the internal PTR	pointer.  Parameter:

	   1.	amount of data to read from the	register

	   2.	register

	   3.	mask applied to	fetched	data

     Predefined	macro: MS_RFETCH_P(iter,reg,mask)

   MS_OP_TRIG -	TRIG register
     is	used to	trigger	the parallel port.  This microinstruction is intended
     to	provide	a very efficient control of the	parallel port.	Triggering a
     register is writing data, wait a while, write data, wait a	while...  This
     allows to write magic sequences to	the port.  Parameter:

	   1.	amount of data to read from the	register

	   2.	register

	   3.	size of	the array

	   4.	array of unsigned chars.  Each couple of u_chars define	the
		data to	write to the register and the delay in us to wait.
		The delay is limited to	255 us to simplify and reduce the size
		of the array.

     Predefined	macro: MS_TRIG(reg,len,array)

   C structures
     union ppb_insarg {
	  int	  i;
	  char	  c;
	  void	  *p;
	  int	  (* f)(void *,	char *);

     struct ppb_microseq {
	  int			  opcode;	  /* microins. opcode */
	  union	ppb_insarg	  arg[PPB_MS_MAXARGS];	  /* arguments */

   Using microsequences
     To	instantiate a microsequence, just declare an array of ppb_microseq
     structures	and initialize it as needed.  You may either use predefined
     macros or code directly your microinstructions according to the ppb_mi-
     croseq definition.	 For example,

	  struct ppb_microseq select_microseq[]	= {

		  /* parameter list
		  #define SELECT_TARGET	   MS_PARAM(0, 1, MS_TYP_INT)

		  /* send the select command to	the drive */

		  /* now, wait until the drive is ready	*/
     /*	loop: */     MS_BRSET(H_ACK, 2 /* ready	*/),
		  MS_DBRA(-2 /*	loop */),
     /*	error: */    MS_RET(1),
     /*	ready: */    MS_RET(0)

     Here, some	parameters are undefined and must be filled before executing
     the microsequence.	 In order to initialize	each microsequence, one	should
     use the ppb_MS_init_msq() function	like this:

	  ppb_MS_init_msq(select_microseq, 2,
			  SELECT_TARGET, 1 << target,
			  SELECT_INITIATOR, 1 << initiator);

     and then execute the microsequence.

   The microsequencer
     The microsequencer	is executed either at ppbus or adapter level (see
     ppbus(4) for info about ppbus system layers). Most	of the microsequencer
     is	executed at ppc	level to avoid ppbus to	adapter	function call over-
     head.  But	some actions like deciding whereas the transfer	is
     IEEE1284-1994 compliant are executed at ppbus layer.

     Only one level of submicrosequences is allowed.

     When triggering the port, maximum delay allowed is	255 us.

     ppbus(4), ppc(4), vpo(4)

     The microseq manual page first appeared in	FreeBSD	3.0.

     This manual page was written by Nicolas Souchu.

BSD				 June 6, 1998				   BSD


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