xref: /openbmc/qemu/hw/misc/macio/mac_dbdma.c (revision 49ab747f)
1 /*
2  * PowerMac descriptor-based DMA emulation
3  *
4  * Copyright (c) 2005-2007 Fabrice Bellard
5  * Copyright (c) 2007 Jocelyn Mayer
6  * Copyright (c) 2009 Laurent Vivier
7  *
8  * some parts from linux-2.6.28, arch/powerpc/include/asm/dbdma.h
9  *
10  *   Definitions for using the Apple Descriptor-Based DMA controller
11  *   in Power Macintosh computers.
12  *
13  *   Copyright (C) 1996 Paul Mackerras.
14  *
15  * some parts from mol 0.9.71
16  *
17  *   Descriptor based DMA emulation
18  *
19  *   Copyright (C) 1998-2004 Samuel Rydh (samuel@ibrium.se)
20  *
21  * Permission is hereby granted, free of charge, to any person obtaining a copy
22  * of this software and associated documentation files (the "Software"), to deal
23  * in the Software without restriction, including without limitation the rights
24  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
25  * copies of the Software, and to permit persons to whom the Software is
26  * furnished to do so, subject to the following conditions:
27  *
28  * The above copyright notice and this permission notice shall be included in
29  * all copies or substantial portions of the Software.
30  *
31  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
32  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
33  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
34  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
35  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
36  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
37  * THE SOFTWARE.
38  */
39 #include "hw/hw.h"
40 #include "hw/isa/isa.h"
41 #include "hw/ppc/mac_dbdma.h"
42 #include "qemu/main-loop.h"
43 
44 /* debug DBDMA */
45 //#define DEBUG_DBDMA
46 
47 #ifdef DEBUG_DBDMA
48 #define DBDMA_DPRINTF(fmt, ...)                                 \
49     do { printf("DBDMA: " fmt , ## __VA_ARGS__); } while (0)
50 #else
51 #define DBDMA_DPRINTF(fmt, ...)
52 #endif
53 
54 /*
55  */
56 
57 /*
58  * DBDMA control/status registers.  All little-endian.
59  */
60 
61 #define DBDMA_CONTROL         0x00
62 #define DBDMA_STATUS          0x01
63 #define DBDMA_CMDPTR_HI       0x02
64 #define DBDMA_CMDPTR_LO       0x03
65 #define DBDMA_INTR_SEL        0x04
66 #define DBDMA_BRANCH_SEL      0x05
67 #define DBDMA_WAIT_SEL        0x06
68 #define DBDMA_XFER_MODE       0x07
69 #define DBDMA_DATA2PTR_HI     0x08
70 #define DBDMA_DATA2PTR_LO     0x09
71 #define DBDMA_RES1            0x0A
72 #define DBDMA_ADDRESS_HI      0x0B
73 #define DBDMA_BRANCH_ADDR_HI  0x0C
74 #define DBDMA_RES2            0x0D
75 #define DBDMA_RES3            0x0E
76 #define DBDMA_RES4            0x0F
77 
78 #define DBDMA_REGS            16
79 #define DBDMA_SIZE            (DBDMA_REGS * sizeof(uint32_t))
80 
81 #define DBDMA_CHANNEL_SHIFT   7
82 #define DBDMA_CHANNEL_SIZE    (1 << DBDMA_CHANNEL_SHIFT)
83 
84 #define DBDMA_CHANNELS        (0x1000 >> DBDMA_CHANNEL_SHIFT)
85 
86 /* Bits in control and status registers */
87 
88 #define RUN	0x8000
89 #define PAUSE	0x4000
90 #define FLUSH	0x2000
91 #define WAKE	0x1000
92 #define DEAD	0x0800
93 #define ACTIVE	0x0400
94 #define BT	0x0100
95 #define DEVSTAT	0x00ff
96 
97 /*
98  * DBDMA command structure.  These fields are all little-endian!
99  */
100 
101 typedef struct dbdma_cmd {
102     uint16_t req_count;	  /* requested byte transfer count */
103     uint16_t command;	  /* command word (has bit-fields) */
104     uint32_t phy_addr;	  /* physical data address */
105     uint32_t cmd_dep;	  /* command-dependent field */
106     uint16_t res_count;	  /* residual count after completion */
107     uint16_t xfer_status; /* transfer status */
108 } dbdma_cmd;
109 
110 /* DBDMA command values in command field */
111 
112 #define COMMAND_MASK    0xf000
113 #define OUTPUT_MORE	0x0000	/* transfer memory data to stream */
114 #define OUTPUT_LAST	0x1000	/* ditto followed by end marker */
115 #define INPUT_MORE	0x2000	/* transfer stream data to memory */
116 #define INPUT_LAST	0x3000	/* ditto, expect end marker */
117 #define STORE_WORD	0x4000	/* write word (4 bytes) to device reg */
118 #define LOAD_WORD	0x5000	/* read word (4 bytes) from device reg */
119 #define DBDMA_NOP	0x6000	/* do nothing */
120 #define DBDMA_STOP	0x7000	/* suspend processing */
121 
122 /* Key values in command field */
123 
124 #define KEY_MASK        0x0700
125 #define KEY_STREAM0	0x0000	/* usual data stream */
126 #define KEY_STREAM1	0x0100	/* control/status stream */
127 #define KEY_STREAM2	0x0200	/* device-dependent stream */
128 #define KEY_STREAM3	0x0300	/* device-dependent stream */
129 #define KEY_STREAM4	0x0400	/* reserved */
130 #define KEY_REGS	0x0500	/* device register space */
131 #define KEY_SYSTEM	0x0600	/* system memory-mapped space */
132 #define KEY_DEVICE	0x0700	/* device memory-mapped space */
133 
134 /* Interrupt control values in command field */
135 
136 #define INTR_MASK       0x0030
137 #define INTR_NEVER	0x0000	/* don't interrupt */
138 #define INTR_IFSET	0x0010	/* intr if condition bit is 1 */
139 #define INTR_IFCLR	0x0020	/* intr if condition bit is 0 */
140 #define INTR_ALWAYS	0x0030	/* always interrupt */
141 
142 /* Branch control values in command field */
143 
144 #define BR_MASK         0x000c
145 #define BR_NEVER	0x0000	/* don't branch */
146 #define BR_IFSET	0x0004	/* branch if condition bit is 1 */
147 #define BR_IFCLR	0x0008	/* branch if condition bit is 0 */
148 #define BR_ALWAYS	0x000c	/* always branch */
149 
150 /* Wait control values in command field */
151 
152 #define WAIT_MASK       0x0003
153 #define WAIT_NEVER	0x0000	/* don't wait */
154 #define WAIT_IFSET	0x0001	/* wait if condition bit is 1 */
155 #define WAIT_IFCLR	0x0002	/* wait if condition bit is 0 */
156 #define WAIT_ALWAYS	0x0003	/* always wait */
157 
158 typedef struct DBDMA_channel {
159     int channel;
160     uint32_t regs[DBDMA_REGS];
161     qemu_irq irq;
162     DBDMA_io io;
163     DBDMA_rw rw;
164     DBDMA_flush flush;
165     dbdma_cmd current;
166     int processing;
167 } DBDMA_channel;
168 
169 typedef struct {
170     MemoryRegion mem;
171     DBDMA_channel channels[DBDMA_CHANNELS];
172 } DBDMAState;
173 
174 #ifdef DEBUG_DBDMA
175 static void dump_dbdma_cmd(dbdma_cmd *cmd)
176 {
177     printf("dbdma_cmd %p\n", cmd);
178     printf("    req_count 0x%04x\n", le16_to_cpu(cmd->req_count));
179     printf("    command 0x%04x\n", le16_to_cpu(cmd->command));
180     printf("    phy_addr 0x%08x\n", le32_to_cpu(cmd->phy_addr));
181     printf("    cmd_dep 0x%08x\n", le32_to_cpu(cmd->cmd_dep));
182     printf("    res_count 0x%04x\n", le16_to_cpu(cmd->res_count));
183     printf("    xfer_status 0x%04x\n", le16_to_cpu(cmd->xfer_status));
184 }
185 #else
186 static void dump_dbdma_cmd(dbdma_cmd *cmd)
187 {
188 }
189 #endif
190 static void dbdma_cmdptr_load(DBDMA_channel *ch)
191 {
192     DBDMA_DPRINTF("dbdma_cmdptr_load 0x%08x\n",
193                   ch->regs[DBDMA_CMDPTR_LO]);
194     cpu_physical_memory_read(ch->regs[DBDMA_CMDPTR_LO],
195                              (uint8_t*)&ch->current, sizeof(dbdma_cmd));
196 }
197 
198 static void dbdma_cmdptr_save(DBDMA_channel *ch)
199 {
200     DBDMA_DPRINTF("dbdma_cmdptr_save 0x%08x\n",
201                   ch->regs[DBDMA_CMDPTR_LO]);
202     DBDMA_DPRINTF("xfer_status 0x%08x res_count 0x%04x\n",
203                   le16_to_cpu(ch->current.xfer_status),
204                   le16_to_cpu(ch->current.res_count));
205     cpu_physical_memory_write(ch->regs[DBDMA_CMDPTR_LO],
206                               (uint8_t*)&ch->current, sizeof(dbdma_cmd));
207 }
208 
209 static void kill_channel(DBDMA_channel *ch)
210 {
211     DBDMA_DPRINTF("kill_channel\n");
212 
213     ch->regs[DBDMA_STATUS] |= DEAD;
214     ch->regs[DBDMA_STATUS] &= ~ACTIVE;
215 
216     qemu_irq_raise(ch->irq);
217 }
218 
219 static void conditional_interrupt(DBDMA_channel *ch)
220 {
221     dbdma_cmd *current = &ch->current;
222     uint16_t intr;
223     uint16_t sel_mask, sel_value;
224     uint32_t status;
225     int cond;
226 
227     DBDMA_DPRINTF("conditional_interrupt\n");
228 
229     intr = le16_to_cpu(current->command) & INTR_MASK;
230 
231     switch(intr) {
232     case INTR_NEVER:  /* don't interrupt */
233         return;
234     case INTR_ALWAYS: /* always interrupt */
235         qemu_irq_raise(ch->irq);
236         return;
237     }
238 
239     status = ch->regs[DBDMA_STATUS] & DEVSTAT;
240 
241     sel_mask = (ch->regs[DBDMA_INTR_SEL] >> 16) & 0x0f;
242     sel_value = ch->regs[DBDMA_INTR_SEL] & 0x0f;
243 
244     cond = (status & sel_mask) == (sel_value & sel_mask);
245 
246     switch(intr) {
247     case INTR_IFSET:  /* intr if condition bit is 1 */
248         if (cond)
249             qemu_irq_raise(ch->irq);
250         return;
251     case INTR_IFCLR:  /* intr if condition bit is 0 */
252         if (!cond)
253             qemu_irq_raise(ch->irq);
254         return;
255     }
256 }
257 
258 static int conditional_wait(DBDMA_channel *ch)
259 {
260     dbdma_cmd *current = &ch->current;
261     uint16_t wait;
262     uint16_t sel_mask, sel_value;
263     uint32_t status;
264     int cond;
265 
266     DBDMA_DPRINTF("conditional_wait\n");
267 
268     wait = le16_to_cpu(current->command) & WAIT_MASK;
269 
270     switch(wait) {
271     case WAIT_NEVER:  /* don't wait */
272         return 0;
273     case WAIT_ALWAYS: /* always wait */
274         return 1;
275     }
276 
277     status = ch->regs[DBDMA_STATUS] & DEVSTAT;
278 
279     sel_mask = (ch->regs[DBDMA_WAIT_SEL] >> 16) & 0x0f;
280     sel_value = ch->regs[DBDMA_WAIT_SEL] & 0x0f;
281 
282     cond = (status & sel_mask) == (sel_value & sel_mask);
283 
284     switch(wait) {
285     case WAIT_IFSET:  /* wait if condition bit is 1 */
286         if (cond)
287             return 1;
288         return 0;
289     case WAIT_IFCLR:  /* wait if condition bit is 0 */
290         if (!cond)
291             return 1;
292         return 0;
293     }
294     return 0;
295 }
296 
297 static void next(DBDMA_channel *ch)
298 {
299     uint32_t cp;
300 
301     ch->regs[DBDMA_STATUS] &= ~BT;
302 
303     cp = ch->regs[DBDMA_CMDPTR_LO];
304     ch->regs[DBDMA_CMDPTR_LO] = cp + sizeof(dbdma_cmd);
305     dbdma_cmdptr_load(ch);
306 }
307 
308 static void branch(DBDMA_channel *ch)
309 {
310     dbdma_cmd *current = &ch->current;
311 
312     ch->regs[DBDMA_CMDPTR_LO] = current->cmd_dep;
313     ch->regs[DBDMA_STATUS] |= BT;
314     dbdma_cmdptr_load(ch);
315 }
316 
317 static void conditional_branch(DBDMA_channel *ch)
318 {
319     dbdma_cmd *current = &ch->current;
320     uint16_t br;
321     uint16_t sel_mask, sel_value;
322     uint32_t status;
323     int cond;
324 
325     DBDMA_DPRINTF("conditional_branch\n");
326 
327     /* check if we must branch */
328 
329     br = le16_to_cpu(current->command) & BR_MASK;
330 
331     switch(br) {
332     case BR_NEVER:  /* don't branch */
333         next(ch);
334         return;
335     case BR_ALWAYS: /* always branch */
336         branch(ch);
337         return;
338     }
339 
340     status = ch->regs[DBDMA_STATUS] & DEVSTAT;
341 
342     sel_mask = (ch->regs[DBDMA_BRANCH_SEL] >> 16) & 0x0f;
343     sel_value = ch->regs[DBDMA_BRANCH_SEL] & 0x0f;
344 
345     cond = (status & sel_mask) == (sel_value & sel_mask);
346 
347     switch(br) {
348     case BR_IFSET:  /* branch if condition bit is 1 */
349         if (cond)
350             branch(ch);
351         else
352             next(ch);
353         return;
354     case BR_IFCLR:  /* branch if condition bit is 0 */
355         if (!cond)
356             branch(ch);
357         else
358             next(ch);
359         return;
360     }
361 }
362 
363 static QEMUBH *dbdma_bh;
364 static void channel_run(DBDMA_channel *ch);
365 
366 static void dbdma_end(DBDMA_io *io)
367 {
368     DBDMA_channel *ch = io->channel;
369     dbdma_cmd *current = &ch->current;
370 
371     if (conditional_wait(ch))
372         goto wait;
373 
374     current->xfer_status = cpu_to_le16(ch->regs[DBDMA_STATUS]);
375     current->res_count = cpu_to_le16(io->len);
376     dbdma_cmdptr_save(ch);
377     if (io->is_last)
378         ch->regs[DBDMA_STATUS] &= ~FLUSH;
379 
380     conditional_interrupt(ch);
381     conditional_branch(ch);
382 
383 wait:
384     ch->processing = 0;
385     if ((ch->regs[DBDMA_STATUS] & RUN) &&
386         (ch->regs[DBDMA_STATUS] & ACTIVE))
387         channel_run(ch);
388 }
389 
390 static void start_output(DBDMA_channel *ch, int key, uint32_t addr,
391                         uint16_t req_count, int is_last)
392 {
393     DBDMA_DPRINTF("start_output\n");
394 
395     /* KEY_REGS, KEY_DEVICE and KEY_STREAM
396      * are not implemented in the mac-io chip
397      */
398 
399     DBDMA_DPRINTF("addr 0x%x key 0x%x\n", addr, key);
400     if (!addr || key > KEY_STREAM3) {
401         kill_channel(ch);
402         return;
403     }
404 
405     ch->io.addr = addr;
406     ch->io.len = req_count;
407     ch->io.is_last = is_last;
408     ch->io.dma_end = dbdma_end;
409     ch->io.is_dma_out = 1;
410     ch->processing = 1;
411     if (ch->rw) {
412         ch->rw(&ch->io);
413     }
414 }
415 
416 static void start_input(DBDMA_channel *ch, int key, uint32_t addr,
417                        uint16_t req_count, int is_last)
418 {
419     DBDMA_DPRINTF("start_input\n");
420 
421     /* KEY_REGS, KEY_DEVICE and KEY_STREAM
422      * are not implemented in the mac-io chip
423      */
424 
425     if (!addr || key > KEY_STREAM3) {
426         kill_channel(ch);
427         return;
428     }
429 
430     ch->io.addr = addr;
431     ch->io.len = req_count;
432     ch->io.is_last = is_last;
433     ch->io.dma_end = dbdma_end;
434     ch->io.is_dma_out = 0;
435     ch->processing = 1;
436     if (ch->rw) {
437         ch->rw(&ch->io);
438     }
439 }
440 
441 static void load_word(DBDMA_channel *ch, int key, uint32_t addr,
442                      uint16_t len)
443 {
444     dbdma_cmd *current = &ch->current;
445     uint32_t val;
446 
447     DBDMA_DPRINTF("load_word\n");
448 
449     /* only implements KEY_SYSTEM */
450 
451     if (key != KEY_SYSTEM) {
452         printf("DBDMA: LOAD_WORD, unimplemented key %x\n", key);
453         kill_channel(ch);
454         return;
455     }
456 
457     cpu_physical_memory_read(addr, (uint8_t*)&val, len);
458 
459     if (len == 2)
460         val = (val << 16) | (current->cmd_dep & 0x0000ffff);
461     else if (len == 1)
462         val = (val << 24) | (current->cmd_dep & 0x00ffffff);
463 
464     current->cmd_dep = val;
465 
466     if (conditional_wait(ch))
467         goto wait;
468 
469     current->xfer_status = cpu_to_le16(ch->regs[DBDMA_STATUS]);
470     dbdma_cmdptr_save(ch);
471     ch->regs[DBDMA_STATUS] &= ~FLUSH;
472 
473     conditional_interrupt(ch);
474     next(ch);
475 
476 wait:
477     qemu_bh_schedule(dbdma_bh);
478 }
479 
480 static void store_word(DBDMA_channel *ch, int key, uint32_t addr,
481                       uint16_t len)
482 {
483     dbdma_cmd *current = &ch->current;
484     uint32_t val;
485 
486     DBDMA_DPRINTF("store_word\n");
487 
488     /* only implements KEY_SYSTEM */
489 
490     if (key != KEY_SYSTEM) {
491         printf("DBDMA: STORE_WORD, unimplemented key %x\n", key);
492         kill_channel(ch);
493         return;
494     }
495 
496     val = current->cmd_dep;
497     if (len == 2)
498         val >>= 16;
499     else if (len == 1)
500         val >>= 24;
501 
502     cpu_physical_memory_write(addr, (uint8_t*)&val, len);
503 
504     if (conditional_wait(ch))
505         goto wait;
506 
507     current->xfer_status = cpu_to_le16(ch->regs[DBDMA_STATUS]);
508     dbdma_cmdptr_save(ch);
509     ch->regs[DBDMA_STATUS] &= ~FLUSH;
510 
511     conditional_interrupt(ch);
512     next(ch);
513 
514 wait:
515     qemu_bh_schedule(dbdma_bh);
516 }
517 
518 static void nop(DBDMA_channel *ch)
519 {
520     dbdma_cmd *current = &ch->current;
521 
522     if (conditional_wait(ch))
523         goto wait;
524 
525     current->xfer_status = cpu_to_le16(ch->regs[DBDMA_STATUS]);
526     dbdma_cmdptr_save(ch);
527 
528     conditional_interrupt(ch);
529     conditional_branch(ch);
530 
531 wait:
532     qemu_bh_schedule(dbdma_bh);
533 }
534 
535 static void stop(DBDMA_channel *ch)
536 {
537     ch->regs[DBDMA_STATUS] &= ~(ACTIVE|DEAD|FLUSH);
538 
539     /* the stop command does not increment command pointer */
540 }
541 
542 static void channel_run(DBDMA_channel *ch)
543 {
544     dbdma_cmd *current = &ch->current;
545     uint16_t cmd, key;
546     uint16_t req_count;
547     uint32_t phy_addr;
548 
549     DBDMA_DPRINTF("channel_run\n");
550     dump_dbdma_cmd(current);
551 
552     /* clear WAKE flag at command fetch */
553 
554     ch->regs[DBDMA_STATUS] &= ~WAKE;
555 
556     cmd = le16_to_cpu(current->command) & COMMAND_MASK;
557 
558     switch (cmd) {
559     case DBDMA_NOP:
560         nop(ch);
561 	return;
562 
563     case DBDMA_STOP:
564         stop(ch);
565 	return;
566     }
567 
568     key = le16_to_cpu(current->command) & 0x0700;
569     req_count = le16_to_cpu(current->req_count);
570     phy_addr = le32_to_cpu(current->phy_addr);
571 
572     if (key == KEY_STREAM4) {
573         printf("command %x, invalid key 4\n", cmd);
574         kill_channel(ch);
575         return;
576     }
577 
578     switch (cmd) {
579     case OUTPUT_MORE:
580         start_output(ch, key, phy_addr, req_count, 0);
581 	return;
582 
583     case OUTPUT_LAST:
584         start_output(ch, key, phy_addr, req_count, 1);
585 	return;
586 
587     case INPUT_MORE:
588         start_input(ch, key, phy_addr, req_count, 0);
589 	return;
590 
591     case INPUT_LAST:
592         start_input(ch, key, phy_addr, req_count, 1);
593 	return;
594     }
595 
596     if (key < KEY_REGS) {
597         printf("command %x, invalid key %x\n", cmd, key);
598         key = KEY_SYSTEM;
599     }
600 
601     /* for LOAD_WORD and STORE_WORD, req_count is on 3 bits
602      * and BRANCH is invalid
603      */
604 
605     req_count = req_count & 0x0007;
606     if (req_count & 0x4) {
607         req_count = 4;
608         phy_addr &= ~3;
609     } else if (req_count & 0x2) {
610         req_count = 2;
611         phy_addr &= ~1;
612     } else
613         req_count = 1;
614 
615     switch (cmd) {
616     case LOAD_WORD:
617         load_word(ch, key, phy_addr, req_count);
618 	return;
619 
620     case STORE_WORD:
621         store_word(ch, key, phy_addr, req_count);
622 	return;
623     }
624 }
625 
626 static void DBDMA_run(DBDMAState *s)
627 {
628     int channel;
629 
630     for (channel = 0; channel < DBDMA_CHANNELS; channel++) {
631         DBDMA_channel *ch = &s->channels[channel];
632         uint32_t status = ch->regs[DBDMA_STATUS];
633         if (!ch->processing && (status & RUN) && (status & ACTIVE)) {
634             channel_run(ch);
635         }
636     }
637 }
638 
639 static void DBDMA_run_bh(void *opaque)
640 {
641     DBDMAState *s = opaque;
642 
643     DBDMA_DPRINTF("DBDMA_run_bh\n");
644 
645     DBDMA_run(s);
646 }
647 
648 void DBDMA_register_channel(void *dbdma, int nchan, qemu_irq irq,
649                             DBDMA_rw rw, DBDMA_flush flush,
650                             void *opaque)
651 {
652     DBDMAState *s = dbdma;
653     DBDMA_channel *ch = &s->channels[nchan];
654 
655     DBDMA_DPRINTF("DBDMA_register_channel 0x%x\n", nchan);
656 
657     ch->irq = irq;
658     ch->channel = nchan;
659     ch->rw = rw;
660     ch->flush = flush;
661     ch->io.opaque = opaque;
662     ch->io.channel = ch;
663 }
664 
665 static void
666 dbdma_control_write(DBDMA_channel *ch)
667 {
668     uint16_t mask, value;
669     uint32_t status;
670 
671     mask = (ch->regs[DBDMA_CONTROL] >> 16) & 0xffff;
672     value = ch->regs[DBDMA_CONTROL] & 0xffff;
673 
674     value &= (RUN | PAUSE | FLUSH | WAKE | DEVSTAT);
675 
676     status = ch->regs[DBDMA_STATUS];
677 
678     status = (value & mask) | (status & ~mask);
679 
680     if (status & WAKE)
681         status |= ACTIVE;
682     if (status & RUN) {
683         status |= ACTIVE;
684         status &= ~DEAD;
685     }
686     if (status & PAUSE)
687         status &= ~ACTIVE;
688     if ((ch->regs[DBDMA_STATUS] & RUN) && !(status & RUN)) {
689         /* RUN is cleared */
690         status &= ~(ACTIVE|DEAD);
691         if ((status & FLUSH) && ch->flush) {
692             ch->flush(&ch->io);
693             status &= ~FLUSH;
694         }
695     }
696 
697     DBDMA_DPRINTF("    status 0x%08x\n", status);
698 
699     ch->regs[DBDMA_STATUS] = status;
700 
701     if (status & ACTIVE)
702         qemu_bh_schedule(dbdma_bh);
703     if ((status & FLUSH) && ch->flush)
704         ch->flush(&ch->io);
705 }
706 
707 static void dbdma_write(void *opaque, hwaddr addr,
708                         uint64_t value, unsigned size)
709 {
710     int channel = addr >> DBDMA_CHANNEL_SHIFT;
711     DBDMAState *s = opaque;
712     DBDMA_channel *ch = &s->channels[channel];
713     int reg = (addr - (channel << DBDMA_CHANNEL_SHIFT)) >> 2;
714 
715     DBDMA_DPRINTF("writel 0x" TARGET_FMT_plx " <= 0x%08x\n", addr, value);
716     DBDMA_DPRINTF("channel 0x%x reg 0x%x\n",
717                   (uint32_t)addr >> DBDMA_CHANNEL_SHIFT, reg);
718 
719     /* cmdptr cannot be modified if channel is RUN or ACTIVE */
720 
721     if (reg == DBDMA_CMDPTR_LO &&
722         (ch->regs[DBDMA_STATUS] & (RUN | ACTIVE)))
723 	return;
724 
725     ch->regs[reg] = value;
726 
727     switch(reg) {
728     case DBDMA_CONTROL:
729         dbdma_control_write(ch);
730         break;
731     case DBDMA_CMDPTR_LO:
732         /* 16-byte aligned */
733         ch->regs[DBDMA_CMDPTR_LO] &= ~0xf;
734         dbdma_cmdptr_load(ch);
735         break;
736     case DBDMA_STATUS:
737     case DBDMA_INTR_SEL:
738     case DBDMA_BRANCH_SEL:
739     case DBDMA_WAIT_SEL:
740         /* nothing to do */
741         break;
742     case DBDMA_XFER_MODE:
743     case DBDMA_CMDPTR_HI:
744     case DBDMA_DATA2PTR_HI:
745     case DBDMA_DATA2PTR_LO:
746     case DBDMA_ADDRESS_HI:
747     case DBDMA_BRANCH_ADDR_HI:
748     case DBDMA_RES1:
749     case DBDMA_RES2:
750     case DBDMA_RES3:
751     case DBDMA_RES4:
752         /* unused */
753         break;
754     }
755 }
756 
757 static uint64_t dbdma_read(void *opaque, hwaddr addr,
758                            unsigned size)
759 {
760     uint32_t value;
761     int channel = addr >> DBDMA_CHANNEL_SHIFT;
762     DBDMAState *s = opaque;
763     DBDMA_channel *ch = &s->channels[channel];
764     int reg = (addr - (channel << DBDMA_CHANNEL_SHIFT)) >> 2;
765 
766     value = ch->regs[reg];
767 
768     DBDMA_DPRINTF("readl 0x" TARGET_FMT_plx " => 0x%08x\n", addr, value);
769     DBDMA_DPRINTF("channel 0x%x reg 0x%x\n",
770                   (uint32_t)addr >> DBDMA_CHANNEL_SHIFT, reg);
771 
772     switch(reg) {
773     case DBDMA_CONTROL:
774         value = 0;
775         break;
776     case DBDMA_STATUS:
777     case DBDMA_CMDPTR_LO:
778     case DBDMA_INTR_SEL:
779     case DBDMA_BRANCH_SEL:
780     case DBDMA_WAIT_SEL:
781         /* nothing to do */
782         break;
783     case DBDMA_XFER_MODE:
784     case DBDMA_CMDPTR_HI:
785     case DBDMA_DATA2PTR_HI:
786     case DBDMA_DATA2PTR_LO:
787     case DBDMA_ADDRESS_HI:
788     case DBDMA_BRANCH_ADDR_HI:
789         /* unused */
790         value = 0;
791         break;
792     case DBDMA_RES1:
793     case DBDMA_RES2:
794     case DBDMA_RES3:
795     case DBDMA_RES4:
796         /* reserved */
797         break;
798     }
799 
800     return value;
801 }
802 
803 static const MemoryRegionOps dbdma_ops = {
804     .read = dbdma_read,
805     .write = dbdma_write,
806     .endianness = DEVICE_LITTLE_ENDIAN,
807     .valid = {
808         .min_access_size = 4,
809         .max_access_size = 4,
810     },
811 };
812 
813 static const VMStateDescription vmstate_dbdma_channel = {
814     .name = "dbdma_channel",
815     .version_id = 0,
816     .minimum_version_id = 0,
817     .minimum_version_id_old = 0,
818     .fields      = (VMStateField[]) {
819         VMSTATE_UINT32_ARRAY(regs, struct DBDMA_channel, DBDMA_REGS),
820         VMSTATE_END_OF_LIST()
821     }
822 };
823 
824 static const VMStateDescription vmstate_dbdma = {
825     .name = "dbdma",
826     .version_id = 2,
827     .minimum_version_id = 2,
828     .minimum_version_id_old = 2,
829     .fields      = (VMStateField[]) {
830         VMSTATE_STRUCT_ARRAY(channels, DBDMAState, DBDMA_CHANNELS, 1,
831                              vmstate_dbdma_channel, DBDMA_channel),
832         VMSTATE_END_OF_LIST()
833     }
834 };
835 
836 static void dbdma_reset(void *opaque)
837 {
838     DBDMAState *s = opaque;
839     int i;
840 
841     for (i = 0; i < DBDMA_CHANNELS; i++)
842         memset(s->channels[i].regs, 0, DBDMA_SIZE);
843 }
844 
845 void* DBDMA_init (MemoryRegion **dbdma_mem)
846 {
847     DBDMAState *s;
848 
849     s = g_malloc0(sizeof(DBDMAState));
850 
851     memory_region_init_io(&s->mem, &dbdma_ops, s, "dbdma", 0x1000);
852     *dbdma_mem = &s->mem;
853     vmstate_register(NULL, -1, &vmstate_dbdma, s);
854     qemu_register_reset(dbdma_reset, s);
855 
856     dbdma_bh = qemu_bh_new(DBDMA_run_bh, s);
857 
858     return s;
859 }
860