source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/Device/Serial/SerialCommand.asm@ 213

Last change on this file since 213 was 208, checked in by gregli@…, 13 years ago

Enhanced checksum for serial communications, much better at detecting single bit errors.
File size: 19.2 KB
Line 
1; Project name : XTIDE Universal BIOS
2; Description : Serial Device Command functions.
3
4; Section containing code
5SECTION .text
6
7;--------------- UART Equates -----------------------------
8;
9; Serial Programming References:
10; http://en.wikibooks.org/wiki/Serial_Programming
11;
12
13SerialCommand_UART_base EQU 0
14SerialCommand_UART_transmitByte EQU 0
15SerialCommand_UART_receiveByte EQU 0
16SerialCommand_UART_divisorLow EQU 0
17; Values for UART_divisorLow:
18; 60h = 1200, 30h = 2400, 18h = 4800, 0ch = 9600, 6 = 19200, 3 = 38400, 2 = 57600, 1 = 115200
19
20SerialCommand_UART_divisorLow_startingBaud EQU 030h
21; We support 4 baud rates, starting here going higher and skipping every other baud rate
22; Starting with 30h, that means 30h (1200 baud), 0ch (9600 baud), 3 (38400 baud), and 1 (115200 baud)
23; Note: hardware baud multipliers (2x, 4x) will impact the final baud rate and are not known at this level
24
25SerialCommand_UART_interruptEnable EQU 1
26SerialCommand_UART_divisorHigh EQU 1
27; UART_divisorHigh is zero for all speeds including and above 1200 baud
28
29SerialCommand_UART_interruptIdent EQU 2
30SerialCommand_UART_FIFOControl EQU 2
31
32SerialCommand_UART_lineControl EQU 3
33
34SerialCommand_UART_modemControl EQU 4
35
36SerialCommand_UART_lineStatus EQU 5
37
38SerialCommand_UART_modemStatus EQU 6
39
40SerialCommand_UART_scratch EQU 7
41
42SerialCommand_Protocol_Write EQU 3
43SerialCommand_Protocol_Read EQU 2
44SerialCommand_Protocol_Inquire EQU 0
45SerialCommand_Protocol_Header EQU 0a0h
46
47;--------------------------------------------------------------------
48; SerialCommand_OutputWithParameters
49; Parameters:
50; BH: Non-zero if 48-bit addressing used
51; (ignored at present as 48-bit addressing is not supported)
52; BL: IDE Status Register bit to poll after command
53; (ignored at present, since there is no IDE status register to poll)
54; ES:SI: Ptr to buffer (for data transfer commands)
55; DS:DI: Ptr to DPT (in RAMVARS segment)
56; SS:BP: Ptr to IDEREGS_AND_INTPACK
57; Returns:
58; AH: INT 13h Error Code
59; CF: Cleared if success, Set if error
60; Corrupts registers:
61; AL, BX, CX, DX, (ES:SI for data transfer commands)
62;--------------------------------------------------------------------
63ALIGN JUMP_ALIGN
64SerialCommand_OutputWithParameters:
65
66 mov ah,(SerialCommand_Protocol_Header | SerialCommand_Protocol_Read)
67
68 mov al,[bp+IDEPACK.bCommand]
69
70 cmp al,20h ; Read Sectors IDE command
71 jz .readOrWrite
72 inc ah ; now SerialCommand_Protocol_Write
73 cmp al,30h ; Write Sectors IDE command
74 jz .readOrWrite
75
76; all other commands return success
77; including function 0ech which should return drive information, this is handled with the identify functions
78 xor ah,ah ; also clears carry
79 ret
80
81.readOrWrite:
82 mov [bp+IDEPACK.bFeatures],ah ; store protocol command
83
84 mov dl, byte [di+DPT.bSerialPortAndBaud]
85
86; fall-through
87
88;--------------------------------------------------------------------
89; SerialCommand_OutputWithParameters_DeviceInDL
90; Parameters:
91; AH: Protocol Command
92; DL: Packed I/O port and baud rate
93; ES:SI: Ptr to buffer (for data transfer commands)
94; SS:BP: Ptr to IDEREGS_AND_INTPACK
95; Returns:
96; AH: INT 13h Error Code
97; CF: Cleared if success, Set if error
98; Corrupts registers:
99; AL, BX, CX, DX, (ES:SI for data transfer commands)
100;--------------------------------------------------------------------
101SerialCommand_OutputWithParameters_DeviceInDL:
102
103 push si
104 push di
105 push bp
106 push es
107
108;
109; Unpack I/O port and baud from DPT
110; Port to DX more or less for the remainder of the routine
111; Baud in CH until UART initialization is complete
112;
113 mov cl, dl
114
115 and cl, DEVICE_SERIAL_PACKEDPORTANDBAUD_BAUDMASK
116 shl cl, 1
117 mov ch, SerialCommand_UART_divisorLow_startingBaud
118 shr ch, cl
119 adc ch, 0
120
121 and dl, DEVICE_SERIAL_PACKEDPORTANDBAUD_PORTMASK
122 mov dh, 0
123 shl dx, 1 ; port offset already x4, needs one more shift to be x8
124 add dx, DEVICE_SERIAL_PACKEDPORTANDBAUD_STARTINGPORT
125
126;
127; Buffer is referenced through ES:DI throughout, since we need to store faster than we read
128;
129 mov di,si
130
131 mov al,[bp+IDEPACK.bSectorCount]
132
133;
134; Command byte and sector count live at the top of the stack, pop/push are used to access
135;
136 push ax
137
138; cld ; Shouldn't be needed. DF has already been cleared (line 24, Int13h.asm)
139
140;----------------------------------------------------------------------
141;
142; Initialize UART
143;
144; We do this each time since DOS (at boot) or another program may have
145; decided to reprogram the UART
146;
147 push dx
148
149 mov al,83h
150 add dl,SerialCommand_UART_lineControl
151 out dx,al
152
153 mov al,ch
154 pop dx ; divisor low
155 out dx,al
156
157 xor ax,ax
158 inc dx ; divisor high
159 push dx
160 out dx,al
161
162 mov al,047h
163 inc dx ; fifo
164 out dx,al
165
166 mov al,03h
167 inc dx ; linecontrol
168 out dx,al
169
170 mov al,0bh
171 inc dx ; modemcontrol
172 out dx,al
173
174 pop dx ; base, interrupts disabled
175 xor ax,ax
176 out dx,al
177 dec dx
178
179;
180; Start off with a normalized buffer pointer
181;
182 call Registers_NormalizeESDI
183
184;----------------------------------------------------------------------
185;
186; Send Command
187;
188; Sends first six bytes of IDEREGS_AND_INTPACK as the command
189;
190 push es ; save off real buffer location
191 push di
192
193 mov di,bp ; point to IDEREGS for command dispatch;
194 push ss
195 pop es
196
197 xor si,si ; initialize checksum for write
198 dec si
199 mov bp,si
200
201 mov bl,03h ; writing 3 words
202
203 call SerialCommand_WriteProtocol
204
205 pop di ; restore real buffer location
206 pop es
207
208 pop ax ; load command byte (done before call to .nextSector on subsequent iterations)
209 push ax
210
211;
212; Top of the read/write loop, one iteration per sector
213;
214.nextSector:
215 xor si,si ; initialize checksum for read or write
216 dec si
217 mov bp,si
218
219 mov bx,0100h
220
221 shr ah,1 ; command byte, are we doing a write?
222 jnc .readSector
223 call SerialCommand_WriteProtocol
224
225 xor bx,bx
226
227.readSector:
228 mov cx,bx
229 inc cx
230
231 mov bl,dl ; setup bl with proper values for read loop (bh comes later)
232
233;----------------------------------------------------------------------
234;
235; Timeout
236;
237; During read, we first poll in a tight loop, interrupts off, for the next character to come in
238; If that loop completes, then we assume there is a long delay involved, turn interrupts back on
239; and wait for a given number of timer ticks to pass.
240;
241; To save code space, we use the contents of DL to decide which byte in the word to return for reading.
242;
243.readTimeout:
244 push cx
245 xor cx,cx
246.readTimeoutLoop:
247 push dx
248 or dl,SerialCommand_UART_lineStatus
249 in al,dx
250 pop dx
251 shr al,1
252 jc .readTimeoutComplete
253 loop .readTimeoutLoop
254 sti
255 mov bh,1
256 call SerialCommand_WaitAndPoll_Init
257 cli
258.readTimeoutComplete:
259 mov bh,bl
260 or bh,SerialCommand_UART_lineStatus
261
262 pop cx
263 test dl,1
264 jz .readByte1Ready
265 jmp .readByte2Ready
266
267;----------------------------------------------------------------------------
268;
269; Read Block (without interrupts, used when there is a FIFO, high speed)
270;
271; NOTE: This loop is very time sensitive. Literally, another instruction
272; cannot be inserted into this loop without us falling behind at high
273; speed (460.8K baud) on a 4.77Mhz 8088, making it hard to receive
274; a full 512 byte block.
275;
276.readLoop:
277 stosw ; store word in caller's data buffer
278
279 add bp, ax ; update Fletcher's checksum
280 adc bp, 0
281 add si, bp
282 adc si, 0
283
284 mov dl,bh
285 in al,dx
286 shr al,1 ; data ready (byte 1)?
287 mov dl,bl ; get ready to read data
288 jnc .readTimeout ; nope not ready, update timeouts
289
290;
291; Entry point after initial timeout. We enter here so that the checksum word
292; is not stored (and is left in AX after the loop is complete).
293;
294.readByte1Ready:
295 in al, dx ; read data byte 1
296
297 mov ah, al ; store byte in ah for now
298
299;
300; note the placement of this reset of dl to bh, and that it is
301; before the return, which is assymetric with where this is done
302; above for byte 1. The value of dl is used by the timeout routine
303; to know which byte to return to (.read_byte1_ready or
304; .read_byte2_ready)
305;
306 mov dl,bh
307
308 in al,dx
309 shr al,1 ; data ready (byte 2)?
310 jnc .readTimeout
311.readByte2Ready:
312 mov dl,bl
313 in al, dx ; read data byte 2
314
315 xchg al, ah ; ah was holding byte 1, reverse byte order
316
317 loop .readLoop
318
319 sti ; interrupts back on ASAP, if we turned them off
320
321;
322; Compare checksums
323;
324 xchg ax,bp
325 xor ah,al
326 mov cx,si
327 xor cl,ch
328 mov al,cl
329 cmp ax,bp
330 jnz SerialCommand_OutputWithParameters_Error
331
332;
333; Normalize buffer pointer for next go round, if needed
334;
335 test di,di
336 jns .clearBuffer
337 call Registers_NormalizeESDI
338
339;----------------------------------------------------------------------
340;
341; Clear read buffer
342;
343; In case there are extra characters or an error in the FIFO, clear it out.
344; In theory the initialization of the UART registers above should have
345; taken care of this, but I have seen cases where this is not true.
346;
347
348.clearBuffer:
349 mov dl,bh
350 in al,dx
351 mov dl,bl
352 test al,08fh
353 jz .clearBufferComplete
354 shr al,1
355 in al,dx
356 jc .clearBuffer ; note CF from shr above
357 jmp SerialCommand_OutputWithParameters_Error
358
359.clearBufferComplete:
360
361 pop ax ; sector count and command byte
362 dec al ; decrememnt sector count
363 push ax ; save
364 jz SerialCommand_OutputWithParameters_ReturnCodeInALCF ; CF clear from .clearBuffer test above
365
366 cli ; interrupts back off for ACK byte to host
367 ; (host could start sending data immediately)
368 out dx,al ; ACK with next sector number
369
370 jmp .nextSector ; all is well, time for next sector
371
372;---------------------------------------------------------------------------
373;
374; Cleanup, error reporting, and exit
375;
376
377;
378; Used in situations where a call is underway, such as with SerialCommand_WaitAndPoll
379;
380SerialCommand_OutputWithParameters_ErrorAndPop2Words:
381 pop ax
382 pop ax
383
384SerialCommand_OutputWithParameters_Error:
385 stc
386 mov al,1
387
388SerialCommand_OutputWithParameters_ReturnCodeInALCF:
389 sti
390 mov ah,al
391
392 pop bp ; recover ax from stack, throw away
393
394 pop es
395 pop bp
396 pop di
397 pop si
398
399 ret
400
401;--------------------------------------------------------------------
402; SerialCommand_WaitAndPoll
403;
404; Parameters:
405; BH: UART_LineStatus bit to test (20h for write, or 1h for read)
406; DX: Port address (OK if already incremented to UART_lineStatus)
407; Stack: 2 words on the stack below the command/count word
408; Returns:
409; Returns when desired UART_LineStatus bit is cleared
410; Jumps directly to error exit if timeout elapses (and cleans up stack)
411; Corrupts registers:
412; CX, flags
413;--------------------------------------------------------------------
414
415SerialCommand_WaitAndPoll_SoftDelayTicks EQU 20
416
417ALIGN JUMP_ALIGN
418SerialCommand_WaitAndPoll_Init:
419 mov cl,SerialCommand_WaitAndPoll_SoftDelayTicks
420 call Timer_InitializeTimeoutWithTicksInCL
421; fall-through
422
423SerialCommand_WaitAndPoll:
424 call Timer_SetCFifTimeout
425 jc SerialCommand_OutputWithParameters_ErrorAndPop2Words
426 push dx
427 push ax
428 or dl,SerialCommand_UART_lineStatus
429 in al,dx
430 test al,bh
431 pop ax
432 pop dx
433 jz SerialCommand_WaitAndPoll
434; fall-through
435
436SerialCommand_WaitAndPoll_Done:
437 ret
438
439;--------------------------------------------------------------------
440; SerialCommand_WriteProtocol
441;
442; Parameters:
443; ES:DI: Ptr to buffer
444; BL: Words to write (1-255, or 0=256)
445; BP/SI: Initialized for Checksum (-1 in each)
446; DX: I/O Port
447; Returns:
448; BP/SI: Checksum for written bytes, compared against ACK from server in .readLoop
449; Corrupts registers:
450; AX, BX, CX, DI
451;--------------------------------------------------------------------
452ALIGN JUMP_ALIGN
453SerialCommand_WriteProtocol:
454 mov bh,20h
455
456.writeLoop:
457 test bh,1
458 jnz SerialCommand_WaitAndPoll_Done
459
460 mov ax,[es:di] ; fetch next word
461 inc di
462 inc di
463
464 add bp,ax ; update checksum
465 adc bp,0
466 add si,bp
467 adc si,0
468
469.writeLoopChecksum:
470 call SerialCommand_WaitAndPoll_Init
471
472 out dx,al ; output first byte
473
474 call SerialCommand_WaitAndPoll
475
476 mov al,ah ; output second byte
477 out dx,al
478
479 dec bl
480 jnz .writeLoop
481
482 inc bh
483
484 mov ax,bp ; merge checksum for possible write (last loop)
485 xor ah,al
486 mov cx,si
487 xor cl,ch
488 mov al,cl
489
490 jmp .writeLoopChecksum
491
492
493;--------------------------------------------------------------------
494; SerialCommand_IdentifyDeviceToBufferInESSIwithDriveSelectByteInBH
495; Parameters:
496; BH: Drive Select byte for Drive and Head Select Register
497; DS: Segment to RAMVARS
498; ES:SI: Ptr to buffer to receive 512-byte IDE Information
499; CS:BP: Ptr to IDEVARS
500; Returns:
501; AH: INT 13h Error Code
502; NOTE: Not set (or checked) during drive detection
503; CF: Cleared if success, Set if error
504; Corrupts registers:
505; AL, BL, CX, DX, SI, DI, ES
506;--------------------------------------------------------------------
507ALIGN JUMP_ALIGN
508SerialCommand_IdentifyDeviceToBufferInESSIwithDriveSelectByteInBH:
509;
510; To improve boot time, we do our best to avoid looking for slave serial drives when we already know the results
511; from the looking for a master. This is particuarly true when doing a COM port scan, as we will end up running
512; through all the COM ports and baud rates a second time.
513;
514; But drive detection isn't the only case - we also need to get the right drive when called on int13h/25h.
515;
516; The decision tree:
517;
518; Master:
519; bSerialPackedPortAndBaud Non-Zero: -> Continue with bSerialPackedAndBaud (1)
520; bSerialPackedPortAndBaud Zero:
521; bLastSerial Zero: -> Scan (2)
522; bLastSerial Non-Zero: -> Continue with bLastSerial (3)
523;
524; Slave:
525; bSerialPackedPortAndBaud Non-Zero:
526; bLastSerial Zero: -> Error - Not Found (4)
527; bLastSerial Non-Zero: -> Continue with bSerialPackedAndBaud (5)
528; bSerialPackedPortAndBaud Zero:
529; bLastSerial Zero: -> Error - Not Found (4)
530; bLastSerial Non-Zero: -> Continue with bLastSerial (6)
531;
532; (1) This was a port/baud that was explicilty set with the configurator. In the drive detection case, as this
533; is the Master, we are checking out a new controller, and so don't care about the value of bLastSerial.
534; And as with the int13h/25h case, we just go off and get the needed information using the user's setting.
535; (2) We are using the special .ideVarsSerialAuto strucutre. During drive detection, we would only be here
536; if bLastSerial is zero (since we only scan if no explicit drives are set), so we go off to scan.
537; (3) We are using the special .ideVarsSerialAuto strucutre. We won't get here during drive detection, but
538; we might get here on an int13h/25h call. If we have scanned COM drives, they are the ONLY serial drives
539; in use, and so bLastSerial will reflect the port/baud setting for the scanned COM drives.
540; (4) No master has been found yet, therefore no slave should be found. Avoiding the slave reduces boot time,
541; especially in the full COM port scan case. Note that this is different from the hardware IDE, where we
542; will scan for a slave even if a master is not present. Note that if ANY master had been previously found,
543; we will do the slave scan, which isn't harmful, it just wates time. But the most common case (by a wide
544; margin) will be just one serial controller.
545; (5) A COM port scan for a master had been previously completed, and a drive was found. In a multiple serial
546; controller scenario being called with int13h/25h, we need to use the value in bSerialPackedPortAndBaud
547; to make sure we get the proper drive.
548; (6) A COM port scan for a master had been previously completed, and a drive was found. We would only get here
549; if no serial drive was explicitly set by the user in the configurator or that drive had not been found.
550; Instead of performing the full COM port scan for the slave, use the port/baud value stored during the
551; master scan.
552;
553 mov dl,[cs:bp+IDEVARS.bSerialPackedPortAndBaud]
554 mov al, byte [RAMVARS.xlateVars+XLATEVARS.bLastSerial]
555
556 test bh, FLG_DRVNHEAD_DRV
557 jz .master
558
559 test al,al ; Take care of the case that is different between master and slave.
560 jz .error ; Because we do this here, the jz after the "or" below will not be taken
561
562; fall-through
563.master:
564 test dl,dl
565 jnz .identifyDeviceInDL
566
567 or dl,al ; Move bLast into position in dl, as well as test for zero
568 jz .scanSerial
569
570; fall-through
571.identifyDeviceInDL:
572
573 push bp ; setup fake IDEREGS_AND_INTPACK
574
575 push dx
576
577 mov cl,1 ; 1 sector to move
578 push cx
579
580 mov bl,0a0h ; protocol command to ah and onto stack with bh
581 mov ah,bl
582
583 push bx
584
585 mov bp,sp
586 call SerialCommand_OutputWithParameters_DeviceInDL
587
588 pop bx
589
590 pop cx
591 pop dx
592
593 pop bp
594;
595; place packed port/baud in RAMVARS, read by FinalizeDPT and DetectDrives
596;
597; Note that this will be set during an int13h/25h call as well. Which is OK since it is only used (at the
598; top of this routine) for drives found during a COM scan, and we only COM scan if there were no other
599; COM drives found. So we will only reaffirm the port/baud for the one COM port/baud that has a drive.
600;
601 jc .notFound ; only store bLastSerial if success
602 mov byte [RAMVARS.xlateVars+XLATEVARS.bLastSerial], dl
603
604.notFound:
605 ret
606
607;----------------------------------------------------------------------
608;
609; SerialCommand_AutoSerial
610;
611; When the SerialAuto IDEVARS entry is used, scans the COM ports on the machine for a possible serial connection.
612;
613
614.scanPortAddresses: db DEVICE_SERIAL_COM7 >> 2
615 db DEVICE_SERIAL_COM6 >> 2
616 db DEVICE_SERIAL_COM5 >> 2
617 db DEVICE_SERIAL_COM4 >> 2
618 db DEVICE_SERIAL_COM3 >> 2
619 db DEVICE_SERIAL_COM2 >> 2
620 db DEVICE_SERIAL_COM1 >> 2
621 db 0
622
623ALIGN JUMP_ALIGN
624.scanSerial:
625 mov di,.scanPortAddresses-1
626
627.nextPort:
628 inc di ; load next port address
629 mov dl,[cs:di]
630
631 mov dh,0 ; shift from one byte to two
632 eSHL_IM dx, 2
633 jz .error
634
635;
636; Test for COM port presence, write to and read from registers
637;
638 push dx
639 add dl,SerialCommand_UART_lineControl
640 mov al, 09ah
641 out dx, al
642 in al, dx
643 pop dx
644 cmp al, 09ah
645 jnz .nextPort
646
647 mov al, 0ch
648 out dx, al
649 in al, dx
650 cmp al, 0ch
651 jnz .nextPort
652
653;
654; Pack into dl, baud rate starts at 0
655;
656 add dx,-(DEVICE_SERIAL_PACKEDPORTANDBAUD_STARTINGPORT)
657 shr dx,1 ; dh is zero at this point, and will be sent to the server,
658 ; so we know this is an auto detect
659
660 jmp .testFirstBaud
661
662;
663; Walk through 4 possible baud rates
664;
665.nextBaud:
666 inc dx
667 test dl,3
668 jz .nextPort
669
670.testFirstBaud:
671 call .identifyDeviceInDL
672 jc .nextBaud
673
674 ret
675
676.error:
677 stc
678 ; mov ah,1 ; setting the error code is unnecessary as this path can only be taken during
679 ; drive detection, and drive detection works off CF and does not check AH
680 ret
681
682
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