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MICROSEQ(9) FreeBSD Kernel Developer's Manual MICROSEQ(9)
NAME
microseq - ppbus microsequencer developer's guide
SYNOPSIS
#include <sys/types.h>
#include <dev/ppbus/ppbconf.h>
#include <dev/ppbus/ppb_msq.h>
DESCRIPTION
See ppbus(4) for ppbus description and general info about the
microsequencer.
The purpose of this document is to encourage developers to use the
microsequencer mechanism in order to have:
1. a uniform programming model
2. efficient code
Before using microsequences, you are encouraged to look at ppc(4)
microsequencer implementation and an example of how using it in ppi(4).
PPBUS register model
Background
The parallel port model chosen for ppbus is the PC parallel port model.
Thus, any register described later has the same semantic than its
counterpart in a PC parallel port. For more info about ISA/ECP
programming, get the Microsoft standard referenced as "Extended
Capabilities Port Protocol 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
interface.
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
enabling some functions.
MICROINSTRUCTIONS
Description
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
send/receive
o the current value of the internal branch register
This data is modified by some of the microinstructions, not all.
MS_OP_GET and MS_OP_PUT
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.
Parameters:
1. register
2. character mask
3. pointer to the buffer
1. register
2. mask of bits to assert
3. mask of bits to clear
Predefined macro: MS_RSET(reg,assert,clear)
MS_OP_RASSERT - Register ASSERT
is used to assert all bits of a particular parallel port register.
Parameters:
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.
Parameter:
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.
Parameter:
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.
Parameter:
1. integer offset in the current executed (sub)microsequence.
Offset is added to the index of the next microinstruction to
execute.
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.
Parameter:
1. bits of the status register
2. integer offset in the current executed (sub)microsequence.
port are cleared.
Parameter:
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
execute.
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
microsequence. The return code is returned in the integer pointed by the
(int *) parameter of the ppb_MS_microseq().
Parameter:
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.
Parameter:
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
buffer. This pointer is passed to any C call (see above).
Parameter:
1. pointer to the buffer that shall be accessed by xxx_P()
microsequence 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.
Parameter:
1. delay in ms
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
status 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
execute.
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
mandatory 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
microsequence 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
currently 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
The delay is limited to 255 us to simplify and reduce the size
of the array.
Predefined macro: MS_TRIG(reg,len,array)
MICROSEQUENCES
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_microseq definition. For example,
struct ppb_microseq select_microseq[] = {
/* parameter list
*/
#define SELECT_TARGET MS_PARAM(0, 1, MS_TYP_INT)
#define SELECT_INITIATOR MS_PARAM(3, 1, MS_TYP_INT)
/* send the select command to the drive */
MS_DASS(MS_UNKNOWN),
MS_CASS(H_nAUTO | H_nSELIN | H_INIT | H_STROBE),
MS_CASS( H_AUTO | H_nSELIN | H_INIT | H_STROBE),
MS_DASS(MS_UNKNOWN),
MS_CASS( H_AUTO | H_nSELIN | H_nINIT | H_STROBE),
/* now, wait until the drive is ready */
MS_SET(VP0_SELTMO),
/* 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
HISTORY
The microseq manual page first appeared in FreeBSD 3.0.
AUTHORS
This manual page was written by Nicolas Souchu.
BUGS
Only one level of submicrosequences is allowed.
When triggering the port, maximum delay allowed is 255 us.
FreeBSD 14.0-RELEASE-p6 June 6, 1998 FreeBSD 14.0-RELEASE-p6