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source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/Device/Serial/SerialCommand.asm @ 208

Last change on this file since 208 was 208, checked in by gregli@…, 12 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
5	SECTION .text
6
7	;--------------- UART Equates -----------------------------
8	;
9	; Serial Programming References:
10	; http://en.wikibooks.org/wiki/Serial_Programming
11	;
12
13	SerialCommand_UART_base EQU 0
14	SerialCommand_UART_transmitByte EQU 0
15	SerialCommand_UART_receiveByte EQU 0
16	SerialCommand_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
20	SerialCommand_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
25	SerialCommand_UART_interruptEnable EQU 1
26	SerialCommand_UART_divisorHigh EQU 1
27	; UART_divisorHigh is zero for all speeds including and above 1200 baud
28
29	SerialCommand_UART_interruptIdent EQU 2
30	SerialCommand_UART_FIFOControl EQU 2
31
32	SerialCommand_UART_lineControl EQU 3
33
34	SerialCommand_UART_modemControl EQU 4
35
36	SerialCommand_UART_lineStatus EQU 5
37
38	SerialCommand_UART_modemStatus EQU 6
39
40	SerialCommand_UART_scratch EQU 7
41
42	SerialCommand_Protocol_Write EQU 3
43	SerialCommand_Protocol_Read EQU 2
44	SerialCommand_Protocol_Inquire EQU 0
45	SerialCommand_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	;--------------------------------------------------------------------
63	ALIGN JUMP_ALIGN
64	SerialCommand_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	;--------------------------------------------------------------------
101	SerialCommand_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	;
380	SerialCommand_OutputWithParameters_ErrorAndPop2Words:
381	pop ax
382	pop ax
383
384	SerialCommand_OutputWithParameters_Error:
385	stc
386	mov al,1
387
388	SerialCommand_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
415	SerialCommand_WaitAndPoll_SoftDelayTicks EQU 20
416
417	ALIGN JUMP_ALIGN
418	SerialCommand_WaitAndPoll_Init:
419	mov cl,SerialCommand_WaitAndPoll_SoftDelayTicks
420	call Timer_InitializeTimeoutWithTicksInCL
421	; fall-through
422
423	SerialCommand_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
436	SerialCommand_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	;--------------------------------------------------------------------
452	ALIGN JUMP_ALIGN
453	SerialCommand_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	;--------------------------------------------------------------------
507	ALIGN JUMP_ALIGN
508	SerialCommand_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
623	ALIGN 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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