af5f218005e4cf1e34e1cea9bb932aebaf8daf08
[reactos.git] / reactos / drivers / storage / floppy / readwrite.c
1 /*
2 * ReactOS Floppy Driver
3 * Copyright (C) 2004, Vizzini (vizzini@plasmic.com)
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License along
16 * with this program; if not, write to the Free Software Foundation, Inc.,
17 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * PROJECT: ReactOS Floppy Driver
20 * FILE: readwrite.c
21 * PURPOSE: Read/Write handler routines
22 * PROGRAMMER: Vizzini (vizzini@plasmic.com)
23 * REVISIONS:
24 * 15-Feb-2004 vizzini - Created
25 * NOTES:
26 *
27 * READ/WRITE PROCESS
28 *
29 * This process is extracted from the Intel datasheet for the floppy controller.
30 *
31 * - Turn on the motor and set turnoff time
32 * - Program the drive's data rate
33 * - Seek
34 * - Read ID
35 * - Set up DMA
36 * - Send read/write command to FDC
37 * - Read result bytes
38 *
39 * This is mostly implemented in one big function, which watis on the SynchEvent
40 * as many times as necessary to get through the process. See ReadWritePassive() for
41 * more details.
42 *
43 * NOTES:
44 * - Currently doesn't support partial-sector transfers, which is really just a failing
45 * of RWComputeCHS. I've never seen Windows send a partial-sector request, though, so
46 * this may not be a bad thing. Should be looked into, regardless.
47 *
48 * TODO: Break up ReadWritePassive and handle errors better
49 * TODO: Figure out data rate issues
50 * TODO: Media type detection
51 * TODO: Figure out perf issue - waiting after call to read/write for about a second each time
52 * TODO: Figure out specify timings
53 */
54
55 #include "precomp.h"
56
57 #include <debug.h>
58
59 static IO_ALLOCATION_ACTION NTAPI
60 MapRegisterCallback(PDEVICE_OBJECT DeviceObject,
61 PIRP Irp,
62 PVOID MapRegisterBase,
63 PVOID Context)
64 /*
65 * FUNCTION: Acquire map registers in prep for DMA
66 * ARGUMENTS:
67 * DeviceObject: unused
68 * Irp: unused
69 * MapRegisterBase: returned to blocked thread via a member var
70 * Context: contains a pointer to the right ControllerInfo
71 * struct
72 * RETURNS:
73 * KeepObject, because that's what the DDK says to do
74 */
75 {
76 PCONTROLLER_INFO ControllerInfo = (PCONTROLLER_INFO)Context;
77 UNREFERENCED_PARAMETER(DeviceObject);
78 UNREFERENCED_PARAMETER(Irp);
79
80 TRACE_(FLOPPY, "MapRegisterCallback Called\n");
81
82 ControllerInfo->MapRegisterBase = MapRegisterBase;
83 KeSetEvent(&ControllerInfo->SynchEvent, 0, FALSE);
84
85 return KeepObject;
86 }
87
88
89 NTSTATUS NTAPI
90 ReadWrite(PDEVICE_OBJECT DeviceObject, PIRP Irp)
91 /*
92 * FUNCTION: Dispatch routine called for read or write IRPs
93 * ARGUMENTS:
94 * RETURNS:
95 * STATUS_PENDING if the IRP is queued
96 * STATUS_INVALID_PARAMETER if IRP is set up wrong
97 * NOTES:
98 * - This function validates arguments to the IRP and then queues it
99 * - Note that this function is implicitly serialized by the queue logic. Only
100 * one of these at a time is active in the system, no matter how many processors
101 * and threads we have.
102 * - This function stores the DeviceObject in the IRP's context area before dropping
103 * it onto the irp queue
104 */
105 {
106 TRACE_(FLOPPY, "ReadWrite called\n");
107
108 ASSERT(DeviceObject);
109 ASSERT(Irp);
110
111 if(!Irp->MdlAddress)
112 {
113 WARN_(FLOPPY, "ReadWrite(): MDL not found in IRP - Completing with STATUS_INVALID_PARAMETER\n");
114 Irp->IoStatus.Status = STATUS_INVALID_PARAMETER;
115 Irp->IoStatus.Information = 0;
116 IoCompleteRequest(Irp, IO_NO_INCREMENT);
117 return STATUS_INVALID_PARAMETER;
118 }
119
120 /*
121 * Queue the irp to the thread.
122 * The de-queue thread will look in DriverContext[0] for the Device Object.
123 */
124 Irp->Tail.Overlay.DriverContext[0] = DeviceObject;
125 IoCsqInsertIrp(&Csq, Irp, NULL);
126
127 return STATUS_PENDING;
128 }
129
130
131 static VOID NTAPI
132 RWFreeAdapterChannel(PADAPTER_OBJECT AdapterObject)
133 /*
134 * FUNCTION: Free the adapter DMA channel that we allocated
135 * ARGUMENTS:
136 * AdapterObject: the object with the map registers to free
137 * NOTES:
138 * - This function is primarily needed because IoFreeAdapterChannel wants to
139 * be called at DISPATCH_LEVEL
140 */
141 {
142 KIRQL Irql;
143
144 ASSERT(KeGetCurrentIrql() <= DISPATCH_LEVEL);
145
146 KeRaiseIrql(DISPATCH_LEVEL, &Irql);
147 IoFreeAdapterChannel(AdapterObject);
148 KeLowerIrql(Irql);
149 }
150
151
152 static NTSTATUS NTAPI
153 RWDetermineMediaType(PDRIVE_INFO DriveInfo)
154 /*
155 * FUNCTION: Determine the media type of the disk in the drive and fill in the geometry
156 * ARGUMENTS:
157 * DriveInfo: drive to look at
158 * RETURNS:
159 * STATUS_SUCCESS if the media was recognized and the geometry struct was filled in
160 * STATUS_UNRECOGNIZED_MEDIA if not
161 * STATUS_UNSUCCESSFUL if the controller can't be talked to
162 * NOTES:
163 * - Expects the motor to already be running
164 * - Currently only supports 1.44MB 3.5" disks
165 * - PAGED_CODE because it waits
166 * TODO:
167 * - Support more disk types
168 */
169 {
170 UCHAR HeadLoadTime;
171 UCHAR HeadUnloadTime;
172 UCHAR StepRateTime;
173
174 PAGED_CODE();
175
176 TRACE_(FLOPPY, "RWDetermineMediaType called\n");
177
178 /*
179 * This algorithm assumes that a 1.44MB floppy is in the drive. If it's not,
180 * it works backwards until the read works. Note that only 1.44 has been tested
181 * at all.
182 */
183
184 do
185 {
186 int i;
187
188 /* Program data rate */
189 if(HwSetDataRate(DriveInfo->ControllerInfo, DRSR_DSEL_500KBPS) != STATUS_SUCCESS)
190 {
191 WARN_(FLOPPY, "RWDetermineMediaType(): unable to set data rate\n");
192 return STATUS_UNSUCCESSFUL;
193 }
194
195 /* Specify */
196 HeadLoadTime = SPECIFY_HLT_500K;
197 HeadUnloadTime = SPECIFY_HUT_500K;
198 StepRateTime = SPECIFY_SRT_500K;
199
200 /* Don't disable DMA --> enable dma (dumb & confusing) */
201 if(HwSpecify(DriveInfo->ControllerInfo, HeadLoadTime, HeadUnloadTime, StepRateTime, FALSE) != STATUS_SUCCESS)
202 {
203 WARN_(FLOPPY, "RWDetermineMediaType(): specify failed\n");
204 return STATUS_UNSUCCESSFUL;
205 }
206
207 /* clear any spurious interrupts in preparation for recalibrate */
208 KeClearEvent(&DriveInfo->ControllerInfo->SynchEvent);
209
210 /* Recalibrate --> head over first track */
211 for(i=0; i < 2; i++)
212 {
213 NTSTATUS RecalStatus;
214
215 if(HwRecalibrate(DriveInfo) != STATUS_SUCCESS)
216 {
217 WARN_(FLOPPY, "RWDetermineMediaType(): Recalibrate failed\n");
218 return STATUS_UNSUCCESSFUL;
219 }
220
221 /* Wait for the recalibrate to finish */
222 WaitForControllerInterrupt(DriveInfo->ControllerInfo);
223
224 RecalStatus = HwRecalibrateResult(DriveInfo->ControllerInfo);
225
226 if(RecalStatus == STATUS_SUCCESS)
227 break;
228
229 if(i == 1) /* failed for 2nd time */
230 {
231 WARN_(FLOPPY, "RWDetermineMediaType(): RecalibrateResult failed\n");
232 return STATUS_UNSUCCESSFUL;
233 }
234 }
235
236 /* clear any spurious interrupts */
237 KeClearEvent(&DriveInfo->ControllerInfo->SynchEvent);
238
239 /* Try to read an ID */
240 if(HwReadId(DriveInfo, 0) != STATUS_SUCCESS) /* read the first ID we find, from head 0 */
241 {
242 WARN_(FLOPPY, "RWDetermineMediaType(): ReadId failed\n");
243 return STATUS_UNSUCCESSFUL; /* if we can't even write to the controller, it's hopeless */
244 }
245
246 /* Wait for the ReadID to finish */
247 WaitForControllerInterrupt(DriveInfo->ControllerInfo);
248
249 if(HwReadIdResult(DriveInfo->ControllerInfo, NULL, NULL) != STATUS_SUCCESS)
250 {
251 WARN_(FLOPPY, "RWDetermineMediaType(): ReadIdResult failed; continuing\n");
252 continue;
253 }
254
255 /* Found the media; populate the geometry now */
256 WARN_(FLOPPY, "Hardcoded media type!\n");
257 INFO_(FLOPPY, "RWDetermineMediaType(): Found 1.44 media; returning success\n");
258 DriveInfo->DiskGeometry.MediaType = GEOMETRY_144_MEDIATYPE;
259 DriveInfo->DiskGeometry.Cylinders.QuadPart = GEOMETRY_144_CYLINDERS;
260 DriveInfo->DiskGeometry.TracksPerCylinder = GEOMETRY_144_TRACKSPERCYLINDER;
261 DriveInfo->DiskGeometry.SectorsPerTrack = GEOMETRY_144_SECTORSPERTRACK;
262 DriveInfo->DiskGeometry.BytesPerSector = GEOMETRY_144_BYTESPERSECTOR;
263 DriveInfo->BytesPerSectorCode = HW_512_BYTES_PER_SECTOR;
264 return STATUS_SUCCESS;
265 }
266 while(FALSE);
267
268 TRACE_(FLOPPY, "RWDetermineMediaType(): failed to find media\n");
269 return STATUS_UNRECOGNIZED_MEDIA;
270 }
271
272
273 static NTSTATUS NTAPI
274 RWSeekToCylinder(PDRIVE_INFO DriveInfo, UCHAR Cylinder)
275 /*
276 * FUNCTION: Seek a particular drive to a particular track
277 * ARGUMENTS:
278 * DriveInfo: Drive to seek
279 * Cylinder: track to seek to
280 * RETURNS:
281 * STATUS_SUCCESS if the head was successfully seeked
282 * STATUS_UNSUCCESSFUL if not
283 * NOTES:
284 * - PAGED_CODE because it blocks
285 */
286 {
287 UCHAR CurCylinder;
288
289 PAGED_CODE();
290
291 TRACE_(FLOPPY, "RWSeekToCylinder called drive 0x%p cylinder %d\n", DriveInfo, Cylinder);
292
293 /* Clear any spurious interrupts */
294 KeClearEvent(&DriveInfo->ControllerInfo->SynchEvent);
295
296 /* queue seek command */
297 if(HwSeek(DriveInfo, Cylinder) != STATUS_SUCCESS)
298 {
299 WARN_(FLOPPY, "RWSeekToTrack(): unable to seek\n");
300 return STATUS_UNSUCCESSFUL;
301 }
302
303 WaitForControllerInterrupt(DriveInfo->ControllerInfo);
304
305 if(HwSenseInterruptStatus(DriveInfo->ControllerInfo) != STATUS_SUCCESS)
306 {
307 WARN_(FLOPPY, "RWSeekToTrack(): unable to get seek results\n");
308 return STATUS_UNSUCCESSFUL;
309 }
310
311 /* read ID mark from head 0 to verify */
312 if(HwReadId(DriveInfo, 0) != STATUS_SUCCESS)
313 {
314 WARN_(FLOPPY, "RWSeekToTrack(): unable to queue ReadId\n");
315 return STATUS_UNSUCCESSFUL;
316 }
317
318 WaitForControllerInterrupt(DriveInfo->ControllerInfo);
319
320 if(HwReadIdResult(DriveInfo->ControllerInfo, &CurCylinder, NULL) != STATUS_SUCCESS)
321 {
322 WARN_(FLOPPY, "RWSeekToTrack(): unable to get ReadId result\n");
323 return STATUS_UNSUCCESSFUL;
324 }
325
326 if(CurCylinder != Cylinder)
327 {
328 WARN_(FLOPPY, "RWSeekToTrack(): Seeek to track failed; current cylinder is 0x%x\n", CurCylinder);
329 return STATUS_UNSUCCESSFUL;
330 }
331
332 INFO_(FLOPPY, "RWSeekToCylinder: returning successfully, now on cyl %d\n", Cylinder);
333
334 return STATUS_SUCCESS;
335 }
336
337
338 static NTSTATUS NTAPI
339 RWComputeCHS(PDRIVE_INFO IN DriveInfo,
340 ULONG IN DiskByteOffset,
341 PUCHAR OUT Cylinder,
342 PUCHAR OUT Head,
343 PUCHAR OUT Sector)
344 /*
345 * FUNCTION: Compute the CHS from the absolute byte offset on disk
346 * ARGUMENTS:
347 * DriveInfo: Drive to compute on
348 * DiskByteOffset: Absolute offset on disk of the starting byte
349 * Cylinder: Cylinder that the byte is on
350 * Head: Head that the byte is on
351 * Sector: Sector that the byte is on
352 * RETURNS:
353 * STATUS_SUCCESS if CHS are determined correctly
354 * STATUS_UNSUCCESSFUL otherwise
355 * NOTES:
356 * - Lots of ugly typecasts here
357 * - Sectors are 1-based!
358 * - This is really crummy code. Please FIXME.
359 */
360 {
361 ULONG AbsoluteSector;
362 UCHAR SectorsPerCylinder = (UCHAR)DriveInfo->DiskGeometry.SectorsPerTrack * (UCHAR)DriveInfo->DiskGeometry.TracksPerCylinder;
363
364 TRACE_(FLOPPY, "RWComputeCHS: Called with offset 0x%x\n", DiskByteOffset);
365
366 /* First calculate the 1-based "absolute sector" based on the byte offset */
367 ASSERT(!(DiskByteOffset % DriveInfo->DiskGeometry.BytesPerSector)); /* FIXME: Only handle full sector transfers atm */
368
369 /* AbsoluteSector is zero-based to make the math a little easier */
370 AbsoluteSector = DiskByteOffset / DriveInfo->DiskGeometry.BytesPerSector; /* Num full sectors */
371
372 /* Cylinder number is floor(AbsoluteSector / SectorsPerCylinder) */
373 *Cylinder = (CHAR)(AbsoluteSector / SectorsPerCylinder);
374
375 /* Head number is 0 if the sector within the cylinder < SectorsPerTrack; 1 otherwise */
376 *Head = AbsoluteSector % SectorsPerCylinder < DriveInfo->DiskGeometry.SectorsPerTrack ? 0 : 1;
377
378 /*
379 * Sector number is the sector within the cylinder if on head 0; that minus SectorsPerTrack if it's on head 1
380 * (lots of casts to placate msvc). 1-based!
381 */
382 *Sector = ((UCHAR)(AbsoluteSector % SectorsPerCylinder) + 1) - ((*Head) * (UCHAR)DriveInfo->DiskGeometry.SectorsPerTrack);
383
384 INFO_(FLOPPY, "RWComputeCHS: offset 0x%x is c:0x%x h:0x%x s:0x%x\n", DiskByteOffset, *Cylinder, *Head, *Sector);
385
386 /* Sanity checking */
387 ASSERT(*Cylinder <= DriveInfo->DiskGeometry.Cylinders.QuadPart);
388 ASSERT(*Head <= DriveInfo->DiskGeometry.TracksPerCylinder);
389 ASSERT(*Sector <= DriveInfo->DiskGeometry.SectorsPerTrack);
390
391 return STATUS_SUCCESS;
392 }
393
394
395 VOID NTAPI
396 ReadWritePassive(PDRIVE_INFO DriveInfo, PIRP Irp)
397 /*
398 * FUNCTION: Handle the first phase of a read or write IRP
399 * ARGUMENTS:
400 * DeviceObject: DeviceObject that is the target of the IRP
401 * Irp: IRP to process
402 * RETURNS:
403 * STATUS_VERIFY_REQUIRED if the media has changed and we need the filesystems to re-synch
404 * STATUS_SUCCESS otherwise
405 * NOTES:
406 * - Must be called at PASSIVE_LEVEL
407 * - This function is about 250 lines longer than I wanted it to be. Sorry.
408 *
409 * DETAILS:
410 * This routine manages the whole process of servicing a read or write request. It goes like this:
411 * 1) Check the DO_VERIFY_VOLUME flag and return if it's set
412 * 2) Check the disk change line and notify the OS if it's set and return
413 * 3) Detect the media if we haven't already
414 * 4) Set up DiskByteOffset, Length, and WriteToDevice parameters
415 * 5) Get DMA map registers
416 * 6) Then, in a loop for each track, until all bytes are transferred:
417 * a) Compute the current CHS to set the read/write head to
418 * b) Seek to that spot
419 * c) Compute the last sector to transfer on that track
420 * d) Map the transfer through DMA
421 * e) Send the read or write command to the controller
422 * f) Read the results of the command
423 */
424 {
425 PDEVICE_OBJECT DeviceObject = DriveInfo->DeviceObject;
426 PIO_STACK_LOCATION Stack = IoGetCurrentIrpStackLocation(Irp);
427 BOOLEAN WriteToDevice;
428 ULONG Length;
429 ULONG DiskByteOffset;
430 KIRQL OldIrql;
431 NTSTATUS Status;
432 BOOLEAN DiskChanged;
433 ULONG_PTR TransferByteOffset;
434 UCHAR Gap;
435
436 PAGED_CODE();
437
438 TRACE_(FLOPPY, "ReadWritePassive called to %s 0x%x bytes from offset 0x%x\n",
439 (Stack->MajorFunction == IRP_MJ_READ ? "read" : "write"),
440 (Stack->MajorFunction == IRP_MJ_READ ? Stack->Parameters.Read.Length : Stack->Parameters.Write.Length),
441 (Stack->MajorFunction == IRP_MJ_READ ? Stack->Parameters.Read.ByteOffset.u.LowPart :
442 Stack->Parameters.Write.ByteOffset.u.LowPart));
443
444 /* Default return codes */
445 Irp->IoStatus.Status = STATUS_UNSUCCESSFUL;
446 Irp->IoStatus.Information = 0;
447
448 /*
449 * Check to see if the volume needs to be verified. If so,
450 * we can get out of here quickly.
451 */
452 if(DeviceObject->Flags & DO_VERIFY_VOLUME && !(Stack->Flags & SL_OVERRIDE_VERIFY_VOLUME))
453 {
454 INFO_(FLOPPY, "ReadWritePassive(): DO_VERIFY_VOLUME set; Completing with STATUS_VERIFY_REQUIRED\n");
455 Irp->IoStatus.Status = STATUS_VERIFY_REQUIRED;
456 IoCompleteRequest(Irp, IO_NO_INCREMENT);
457 return;
458 }
459
460 /*
461 * Check the change line, and if it's set, return
462 */
463 StartMotor(DriveInfo);
464 if(HwDiskChanged(DeviceObject->DeviceExtension, &DiskChanged) != STATUS_SUCCESS)
465 {
466 WARN_(FLOPPY, "ReadWritePassive(): unable to detect disk change; Completing with STATUS_UNSUCCESSFUL\n");
467 IoCompleteRequest(Irp, IO_NO_INCREMENT);
468 StopMotor(DriveInfo->ControllerInfo);
469 return;
470 }
471
472 if(DiskChanged)
473 {
474 INFO_(FLOPPY, "ReadWritePhase1(): signalling media changed; Completing with STATUS_MEDIA_CHANGED\n");
475
476 /* The following call sets IoStatus.Status and IoStatus.Information */
477 SignalMediaChanged(DeviceObject, Irp);
478
479 /*
480 * Guessing at something... see ioctl.c for more info
481 */
482 if(ResetChangeFlag(DriveInfo) == STATUS_NO_MEDIA_IN_DEVICE)
483 Irp->IoStatus.Status = STATUS_NO_MEDIA_IN_DEVICE;
484
485 IoCompleteRequest(Irp, IO_NO_INCREMENT);
486 StopMotor(DriveInfo->ControllerInfo);
487 return;
488 }
489
490 /*
491 * Figure out the media type, if we don't know it already
492 */
493 if(DriveInfo->DiskGeometry.MediaType == Unknown)
494 {
495 if(RWDetermineMediaType(DriveInfo) != STATUS_SUCCESS)
496 {
497 WARN_(FLOPPY, "ReadWritePassive(): unable to determine media type; completing with STATUS_UNSUCCESSFUL\n");
498 IoCompleteRequest(Irp, IO_NO_INCREMENT);
499 StopMotor(DriveInfo->ControllerInfo);
500 return;
501 }
502
503 if(DriveInfo->DiskGeometry.MediaType == Unknown)
504 {
505 WARN_(FLOPPY, "ReadWritePassive(): Unknown media in drive; completing with STATUS_UNRECOGNIZED_MEDIA\n");
506 Irp->IoStatus.Status = STATUS_UNRECOGNIZED_MEDIA;
507 IoCompleteRequest(Irp, IO_NO_INCREMENT);
508 StopMotor(DriveInfo->ControllerInfo);
509 return;
510 }
511 }
512
513 /* Set up parameters for read or write */
514 if(Stack->MajorFunction == IRP_MJ_READ)
515 {
516 Length = Stack->Parameters.Read.Length;
517 DiskByteOffset = Stack->Parameters.Read.ByteOffset.u.LowPart;
518 WriteToDevice = FALSE;
519 }
520 else
521 {
522 Length = Stack->Parameters.Write.Length;
523 DiskByteOffset = Stack->Parameters.Write.ByteOffset.u.LowPart;
524 WriteToDevice = TRUE;
525 }
526
527 /*
528 * FIXME:
529 * FloppyDeviceData.ReadWriteGapLength specify the value for the physical drive.
530 * We should set this value depend on the format of the inserted disk and possible
531 * depend on the request (read or write). A value of 0 results in one rotation
532 * between the sectors (7.2sec for reading a track).
533 */
534 Gap = DriveInfo->FloppyDeviceData.ReadWriteGapLength;
535
536 /*
537 * Set up DMA transfer
538 *
539 * This is as good of a place as any to document something that used to confuse me
540 * greatly (and I even wrote some of the kernel's DMA code, so if it confuses me, it
541 * probably confuses at least a couple of other people too).
542 *
543 * MmGetMdlVirtualAddress() returns the virtal address, as mapped in the buffer's original
544 * process context, of the MDL. In other words: say you start with a buffer at address X, then
545 * you build an MDL out of that buffer called Mdl. If you call MmGetMdlVirtualAddress(Mdl), it
546 * will return X.
547 *
548 * There are two parameters that the function looks at to produce X again, given the MDL: the
549 * first is the StartVa, which is the base virtual address of the page that the buffer starts
550 * in. If your buffer's virtual address is 0x12345678, StartVa will be 0x12345000, assuming 4K pages
551 * (which is (almost) always the case on x86). Note well: this address is only valid in the
552 * process context that you initially built the MDL from. The physical pages that make up
553 * the MDL might perhaps be mapped in other process contexts too (or even in the system space,
554 * above 0x80000000 (default; 0xc0000000 on current ReactOS or /3GB Windows)), but it will
555 * (possibly) be mapped at a different address.
556 *
557 * The second parameter is the ByteOffset. Given an original buffer address of 0x12345678,
558 * the ByteOffset would be 0x678. Because MDLs can only describe full pages (and therefore
559 * StartVa always points to the start address of a page), the ByteOffset must be used to
560 * find the real start of the buffer.
561 *
562 * In general, if you add the StartVa and ByteOffset together, you get back your original
563 * buffer pointer, which you are free to use if you're sure you're in the right process
564 * context. You could tell by accessing the (hidden and not-to-be-used) Process member of
565 * the MDL, but in general, if you have to ask whether or not you are in the right context,
566 * then you shouldn't be using this address for anything anyway. There are also security implications
567 * (big ones, really, I wouldn't kid about this) to directly accessing a user's buffer by VA, so
568 * Don't Do That.
569 *
570 * There is a somewhat weird but very common use of the virtual address associated with a MDL
571 * that pops up often in the context of DMA. DMA APIs (particularly MapTransfer()) need to
572 * know where the memory is that they should DMA into and out of. This memory is described
573 * by a MDL. The controller eventually needs to know a physical address on the host side,
574 * which is generally a 32-bit linear address (on x86), and not just a page address. Therefore,
575 * the DMA APIs look at the ByteOffset field of the MDL to reconstruct the real address that
576 * should be programmed into the DMA controller.
577 *
578 * It is often the case that a transfer needs to be broken down over more than one DMA operation,
579 * particularly when it is a big transfer and the HAL doesn't give you enough map registers
580 * to map the whole thing at once. Therefore, the APIs need a way to tell how far into the MDL
581 * they should look to transfer the next chunk of bytes. Now, Microsoft could have designed
582 * MapTransfer to take a "MDL offset" argument, starting with 0, for how far into the buffer to
583 * start, but it didn't. Instead, MapTransfer asks for the virtual address of the MDL as an "index" into
584 * the MDL. The way it computes how far into the page to start the transfer is by masking off all but
585 * the bottom 12 bits (on x86) of the number you supply as the CurrentVa and using *that* as the
586 * ByteOffset instead of the one in the MDL. (OK, this varies a bit by OS and version, but this
587 * is the effect).
588 *
589 * In other words, you get a number back from MmGetMdlVirtualAddress that represents the start of your
590 * buffer, and you pass it to the first MapTransfer call. Then, for each successive operation
591 * on the same buffer, you increment that address to point to the next spot in the MDL that
592 * you want to DMA to/from. The fact that the virtual address you're manipulating is probably not
593 * mapped into the process context that you're running in is irrelevant, since it's only being
594 * used to index into the MDL.
595 */
596
597 /* Get map registers for DMA */
598 KeRaiseIrql(DISPATCH_LEVEL, &OldIrql);
599 Status = IoAllocateAdapterChannel(DriveInfo->ControllerInfo->AdapterObject, DeviceObject,
600 DriveInfo->ControllerInfo->MapRegisters, MapRegisterCallback, DriveInfo->ControllerInfo);
601 KeLowerIrql(OldIrql);
602
603 if(Status != STATUS_SUCCESS)
604 {
605 WARN_(FLOPPY, "ReadWritePassive(): unable allocate an adapter channel; completing with STATUS_UNSUCCESSFUL\n");
606 IoCompleteRequest(Irp, IO_NO_INCREMENT);
607 StopMotor(DriveInfo->ControllerInfo);
608 return ;
609 }
610
611
612 /*
613 * Read from (or write to) the device
614 *
615 * This has to be called in a loop, as you can only transfer data to/from a single track at
616 * a time.
617 */
618 TransferByteOffset = 0;
619 while(TransferByteOffset < Length)
620 {
621 UCHAR Cylinder;
622 UCHAR Head;
623 UCHAR StartSector;
624 ULONG CurrentTransferBytes;
625 UCHAR CurrentTransferSectors;
626
627 INFO_(FLOPPY, "ReadWritePassive(): iterating in while (TransferByteOffset = 0x%x of 0x%x total) - allocating %d registers\n",
628 TransferByteOffset, Length, DriveInfo->ControllerInfo->MapRegisters);
629
630 KeClearEvent(&DriveInfo->ControllerInfo->SynchEvent);
631
632 /*
633 * Compute starting CHS
634 */
635 if(RWComputeCHS(DriveInfo, DiskByteOffset+TransferByteOffset, &Cylinder, &Head, &StartSector) != STATUS_SUCCESS)
636 {
637 WARN_(FLOPPY, "ReadWritePassive(): unable to compute CHS; completing with STATUS_UNSUCCESSFUL\n");
638 RWFreeAdapterChannel(DriveInfo->ControllerInfo->AdapterObject);
639 IoCompleteRequest(Irp, IO_NO_INCREMENT);
640 StopMotor(DriveInfo->ControllerInfo);
641 return;
642 }
643
644 /*
645 * Seek to the right track
646 */
647 if(!DriveInfo->ControllerInfo->ImpliedSeeks)
648 {
649 if(RWSeekToCylinder(DriveInfo, Cylinder) != STATUS_SUCCESS)
650 {
651 WARN_(FLOPPY, "ReadWritePassive(): unable to seek; completing with STATUS_UNSUCCESSFUL\n");
652 RWFreeAdapterChannel(DriveInfo->ControllerInfo->AdapterObject);
653 IoCompleteRequest(Irp, IO_NO_INCREMENT);
654 StopMotor(DriveInfo->ControllerInfo);
655 return ;
656 }
657 }
658
659 /*
660 * Compute last sector
661 *
662 * We can only ask for a transfer up to the end of the track. Then we have to re-seek and do more.
663 * TODO: Support the MT bit
664 */
665 INFO_(FLOPPY, "ReadWritePassive(): computing number of sectors to transfer (StartSector 0x%x): ", StartSector);
666
667 /* 1-based sector number */
668 if( (((DriveInfo->DiskGeometry.TracksPerCylinder - Head) * DriveInfo->DiskGeometry.SectorsPerTrack - StartSector) + 1 ) <
669 (Length - TransferByteOffset) / DriveInfo->DiskGeometry.BytesPerSector)
670 {
671 CurrentTransferSectors = (UCHAR)((DriveInfo->DiskGeometry.TracksPerCylinder - Head) * DriveInfo->DiskGeometry.SectorsPerTrack - StartSector) + 1;
672 }
673 else
674 {
675 CurrentTransferSectors = (UCHAR)((Length - TransferByteOffset) / DriveInfo->DiskGeometry.BytesPerSector);
676 }
677
678 INFO_(FLOPPY, "0x%x\n", CurrentTransferSectors);
679
680 CurrentTransferBytes = CurrentTransferSectors * DriveInfo->DiskGeometry.BytesPerSector;
681
682 /*
683 * Adjust to map registers
684 * BUG: Does this take into account page crossings?
685 */
686 INFO_(FLOPPY, "ReadWritePassive(): Trying to transfer 0x%x bytes\n", CurrentTransferBytes);
687
688 ASSERT(CurrentTransferBytes);
689
690 if(BYTES_TO_PAGES(CurrentTransferBytes) > DriveInfo->ControllerInfo->MapRegisters)
691 {
692 CurrentTransferSectors = (UCHAR)((DriveInfo->ControllerInfo->MapRegisters * PAGE_SIZE) /
693 DriveInfo->DiskGeometry.BytesPerSector);
694
695 CurrentTransferBytes = CurrentTransferSectors * DriveInfo->DiskGeometry.BytesPerSector;
696
697 INFO_(FLOPPY, "ReadWritePassive: limiting transfer to 0x%x bytes (0x%x sectors) due to map registers\n",
698 CurrentTransferBytes, CurrentTransferSectors);
699 }
700
701 /* set up this round's dma operation */
702 /* param 2 is ReadOperation --> opposite of WriteToDevice that IoMapTransfer takes. BAD MS. */
703 KeFlushIoBuffers(Irp->MdlAddress, !WriteToDevice, TRUE);
704
705 IoMapTransfer(DriveInfo->ControllerInfo->AdapterObject, Irp->MdlAddress,
706 DriveInfo->ControllerInfo->MapRegisterBase,
707 (PVOID)((ULONG_PTR)MmGetMdlVirtualAddress(Irp->MdlAddress) + TransferByteOffset),
708 &CurrentTransferBytes, WriteToDevice);
709
710 /*
711 * Read or Write
712 */
713 KeClearEvent(&DriveInfo->ControllerInfo->SynchEvent);
714
715 /* Issue the read/write command to the controller. Note that it expects the opposite of WriteToDevice. */
716 if(HwReadWriteData(DriveInfo->ControllerInfo, !WriteToDevice, DriveInfo->UnitNumber, Cylinder, Head, StartSector,
717 DriveInfo->BytesPerSectorCode, DriveInfo->DiskGeometry.SectorsPerTrack, Gap, 0xff) != STATUS_SUCCESS)
718 {
719 WARN_(FLOPPY, "ReadWritePassive(): HwReadWriteData returned failure; unable to read; completing with STATUS_UNSUCCESSFUL\n");
720 RWFreeAdapterChannel(DriveInfo->ControllerInfo->AdapterObject);
721 IoCompleteRequest(Irp, IO_NO_INCREMENT);
722 StopMotor(DriveInfo->ControllerInfo);
723 return ;
724 }
725
726 INFO_(FLOPPY, "ReadWritePassive(): HwReadWriteData returned -- waiting on event\n");
727
728 /*
729 * At this point, we block and wait for an interrupt
730 * FIXME: this seems to take too long
731 */
732 WaitForControllerInterrupt(DriveInfo->ControllerInfo);
733
734 /* Read is complete; flush & free adapter channel */
735 IoFlushAdapterBuffers(DriveInfo->ControllerInfo->AdapterObject, Irp->MdlAddress,
736 DriveInfo->ControllerInfo->MapRegisterBase,
737 (PVOID)((ULONG_PTR)MmGetMdlVirtualAddress(Irp->MdlAddress) + TransferByteOffset),
738 CurrentTransferBytes, WriteToDevice);
739
740 /* Read the results from the drive */
741 if(HwReadWriteResult(DriveInfo->ControllerInfo) != STATUS_SUCCESS)
742 {
743 WARN_(FLOPPY, "ReadWritePassive(): HwReadWriteResult returned failure; unable to read; completing with STATUS_UNSUCCESSFUL\n");
744 HwDumpRegisters(DriveInfo->ControllerInfo);
745 RWFreeAdapterChannel(DriveInfo->ControllerInfo->AdapterObject);
746 IoCompleteRequest(Irp, IO_NO_INCREMENT);
747 StopMotor(DriveInfo->ControllerInfo);
748 return ;
749 }
750
751 TransferByteOffset += CurrentTransferBytes;
752 }
753
754 RWFreeAdapterChannel(DriveInfo->ControllerInfo->AdapterObject);
755
756 /* That's all folks! */
757 INFO_(FLOPPY, "ReadWritePassive(): success; Completing with STATUS_SUCCESS\n");
758 Irp->IoStatus.Status = STATUS_SUCCESS;
759 Irp->IoStatus.Information = Length;
760 IoCompleteRequest(Irp, IO_DISK_INCREMENT);
761 StopMotor(DriveInfo->ControllerInfo);
762 }