Merge branch 'upstream-linus' of master.kernel.org:/pub/scm/linux/kernel/git/jgarzik...
[linux-2.6] / drivers / scsi / atari_dma_emul.c
1 /*
2  * atari_dma_emul.c -- TT SCSI DMA emulator for the Hades.
3  *
4  * Copyright 1997 Wout Klaren <W.Klaren@inter.nl.net>
5  *
6  * This file is subject to the terms and conditions of the GNU General Public
7  * License.  See the file COPYING in the main directory of this archive
8  * for more details.
9  *
10  * This code was written using the Hades TOS source code as a
11  * reference. This source code can be found on the home page
12  * of Medusa Computer Systems.
13  *
14  * Version 0.1, 1997-09-24.
15  * 
16  * This code should be considered experimental. It has only been
17  * tested on a Hades with a 68060. It might not work on a Hades
18  * with a 68040. Make backups of your hard drives before using
19  * this code.
20  */
21
22 #include <linux/compiler.h>
23 #include <asm/thread_info.h>
24 #include <asm/uaccess.h>
25
26 #define hades_dma_ctrl          (*(unsigned char *) 0xffff8717)
27 #define hades_psdm_reg          (*(unsigned char *) 0xffff8741)
28
29 #define TRANSFER_SIZE           16
30
31 struct m68040_frame {
32         unsigned long  effaddr;  /* effective address */
33         unsigned short ssw;      /* special status word */
34         unsigned short wb3s;     /* write back 3 status */
35         unsigned short wb2s;     /* write back 2 status */
36         unsigned short wb1s;     /* write back 1 status */
37         unsigned long  faddr;    /* fault address */
38         unsigned long  wb3a;     /* write back 3 address */
39         unsigned long  wb3d;     /* write back 3 data */
40         unsigned long  wb2a;     /* write back 2 address */
41         unsigned long  wb2d;     /* write back 2 data */
42         unsigned long  wb1a;     /* write back 1 address */
43         unsigned long  wb1dpd0;  /* write back 1 data/push data 0*/
44         unsigned long  pd1;      /* push data 1*/
45         unsigned long  pd2;      /* push data 2*/
46         unsigned long  pd3;      /* push data 3*/
47 };
48
49 static void writeback (unsigned short wbs, unsigned long wba,
50                        unsigned long wbd, void *old_buserr)
51 {
52         mm_segment_t fs = get_fs();
53         static void *save_buserr;
54
55         __asm__ __volatile__ ("movec.l  %%vbr,%%a0\n\t"
56                               "move.l   %0,8(%%a0)\n\t"
57                               :
58                               : "r" (&&bus_error)
59                               : "a0" );
60
61         save_buserr = old_buserr;
62
63         set_fs (MAKE_MM_SEG(wbs & WBTM_040));
64
65         switch (wbs & WBSIZ_040) {
66             case BA_SIZE_BYTE:
67                 put_user (wbd & 0xff, (char *)wba);
68                 break;
69             case BA_SIZE_WORD:
70                 put_user (wbd & 0xffff, (short *)wba);
71                 break;
72             case BA_SIZE_LONG:
73                 put_user (wbd, (int *)wba);
74                 break;
75         }
76
77         set_fs (fs);
78         return;
79
80 bus_error:
81         __asm__ __volatile__ ("cmp.l    %0,2(%%sp)\n\t"
82                               "bcs.s    .jump_old\n\t"
83                               "cmp.l    %1,2(%%sp)\n\t"
84                               "bls.s    .restore_old\n"
85                         ".jump_old:\n\t"
86                               "move.l   %2,-(%%sp)\n\t"
87                               "rts\n"
88                         ".restore_old:\n\t"
89                               "move.l   %%a0,-(%%sp)\n\t"
90                               "movec.l  %%vbr,%%a0\n\t"
91                               "move.l   %2,8(%%a0)\n\t"
92                               "move.l   (%%sp)+,%%a0\n\t"
93                               "rte\n\t"
94                               :
95                               : "i" (writeback), "i" (&&bus_error),
96                                 "m" (save_buserr) );
97 }
98
99 /*
100  * static inline void set_restdata_reg(unsigned char *cur_addr)
101  *
102  * Set the rest data register if necessary.
103  */
104
105 static inline void set_restdata_reg(unsigned char *cur_addr)
106 {
107         if (((long) cur_addr & ~3) != 0)
108                 tt_scsi_dma.dma_restdata =
109                         *((unsigned long *) ((long) cur_addr & ~3));
110 }
111
112 /*
113  * void hades_dma_emulator(int irq, void *dummy)
114  * 
115  * This code emulates TT SCSI DMA on the Hades.
116  * 
117  * Note the following:
118  * 
119  * 1. When there is no byte available to read from the SCSI bus, or
120  *    when a byte cannot yet bet written to the SCSI bus, a bus
121  *    error occurs when reading or writing the pseudo DMA data
122  *    register (hades_psdm_reg). We have to catch this bus error
123  *    and try again to read or write the byte. If after several tries
124  *    we still get a bus error, the interrupt handler is left. When
125  *    the byte can be read or written, the interrupt handler is
126  *    called again.
127  * 
128  * 2. The SCSI interrupt must be disabled in this interrupt handler.
129  * 
130  * 3. If we set the EOP signal, the SCSI controller still expects one
131  *    byte to be read or written. Therefore the last byte is transferred
132  *    separately, after setting the EOP signal.
133  * 
134  * 4. When this function is left, the address pointer (start_addr) is
135  *    converted to a physical address. Because it points one byte
136  *    further than the last transferred byte, it can point outside the
137  *    current page. If virt_to_phys() is called with this address we
138  *    might get an access error. Therefore virt_to_phys() is called with
139  *    start_addr - 1 if the count has reached zero. The result is
140  *    increased with one.
141  */
142
143 static irqreturn_t hades_dma_emulator(int irq, void *dummy)
144 {
145         unsigned long dma_base;
146         register unsigned long dma_cnt asm ("d3");
147         static long save_buserr;
148         register unsigned long save_sp asm ("d4");
149         register int tries asm ("d5");
150         register unsigned char *start_addr asm ("a3"), *end_addr asm ("a4");
151         register unsigned char *eff_addr;
152         register unsigned char *psdm_reg;
153         unsigned long rem;
154
155         atari_disable_irq(IRQ_TT_MFP_SCSI);
156
157         /*
158          * Read the dma address and count registers.
159          */
160
161         dma_base = SCSI_DMA_READ_P(dma_addr);
162         dma_cnt = SCSI_DMA_READ_P(dma_cnt);
163
164         /*
165          * Check if DMA is still enabled.
166          */
167
168         if ((tt_scsi_dma.dma_ctrl & 2) == 0)
169         {
170                 atari_enable_irq(IRQ_TT_MFP_SCSI);
171                 return IRQ_HANDLED;
172         }
173
174         if (dma_cnt == 0)
175         {
176                 printk(KERN_NOTICE "DMA emulation: count is zero.\n");
177                 tt_scsi_dma.dma_ctrl &= 0xfd;   /* DMA ready. */
178                 atari_enable_irq(IRQ_TT_MFP_SCSI);
179                 return IRQ_HANDLED;
180         }
181
182         /*
183          * Install new bus error routine.
184          */
185
186         __asm__ __volatile__ ("movec.l  %%vbr,%%a0\n\t"
187                               "move.l   8(%%a0),%0\n\t"
188                               "move.l   %1,8(%%a0)\n\t"
189                               : "=&r" (save_buserr)
190                               : "r" (&&scsi_bus_error)
191                               : "a0" );
192
193         hades_dma_ctrl &= 0xfc;         /* Bus error and EOP off. */
194
195         /*
196          * Save the stack pointer.
197          */
198
199         __asm__ __volatile__ ("move.l   %%sp,%0\n\t"
200                               : "=&r" (save_sp) );
201
202         tries = 100;                    /* Maximum number of bus errors. */
203         start_addr = phys_to_virt(dma_base);
204         end_addr = start_addr + dma_cnt;
205
206 scsi_loop:
207         dma_cnt--;
208         rem = dma_cnt & (TRANSFER_SIZE - 1);
209         dma_cnt &= ~(TRANSFER_SIZE - 1);
210         psdm_reg = &hades_psdm_reg;
211
212         if (tt_scsi_dma.dma_ctrl & 1)   /* Read or write? */
213         {
214                 /*
215                  * SCSI write. Abort when count is zero.
216                  */
217
218                 switch (rem)
219                 {
220                 case 0:
221                         while (dma_cnt > 0)
222                         {
223                                 dma_cnt -= TRANSFER_SIZE;
224
225                                 *psdm_reg = *start_addr++;
226                 case 15:
227                                 *psdm_reg = *start_addr++;
228                 case 14:
229                                 *psdm_reg = *start_addr++;
230                 case 13:
231                                 *psdm_reg = *start_addr++;
232                 case 12:
233                                 *psdm_reg = *start_addr++;
234                 case 11:
235                                 *psdm_reg = *start_addr++;
236                 case 10:
237                                 *psdm_reg = *start_addr++;
238                 case 9:
239                                 *psdm_reg = *start_addr++;
240                 case 8:
241                                 *psdm_reg = *start_addr++;
242                 case 7:
243                                 *psdm_reg = *start_addr++;
244                 case 6:
245                                 *psdm_reg = *start_addr++;
246                 case 5:
247                                 *psdm_reg = *start_addr++;
248                 case 4:
249                                 *psdm_reg = *start_addr++;
250                 case 3:
251                                 *psdm_reg = *start_addr++;
252                 case 2:
253                                 *psdm_reg = *start_addr++;
254                 case 1:
255                                 *psdm_reg = *start_addr++;
256                         }
257                 }
258
259                 hades_dma_ctrl |= 1;    /* Set EOP. */
260                 udelay(10);
261                 *psdm_reg = *start_addr++;      /* Dummy byte. */
262                 tt_scsi_dma.dma_ctrl &= 0xfd;   /* DMA ready. */
263         }
264         else
265         {
266                 /*
267                  * SCSI read. Abort when count is zero.
268                  */
269
270                 switch (rem)
271                 {
272                 case 0:
273                         while (dma_cnt > 0)
274                         {
275                                 dma_cnt -= TRANSFER_SIZE;
276
277                                 *start_addr++ = *psdm_reg;
278                 case 15:
279                                 *start_addr++ = *psdm_reg;
280                 case 14:
281                                 *start_addr++ = *psdm_reg;
282                 case 13:
283                                 *start_addr++ = *psdm_reg;
284                 case 12:
285                                 *start_addr++ = *psdm_reg;
286                 case 11:
287                                 *start_addr++ = *psdm_reg;
288                 case 10:
289                                 *start_addr++ = *psdm_reg;
290                 case 9:
291                                 *start_addr++ = *psdm_reg;
292                 case 8:
293                                 *start_addr++ = *psdm_reg;
294                 case 7:
295                                 *start_addr++ = *psdm_reg;
296                 case 6:
297                                 *start_addr++ = *psdm_reg;
298                 case 5:
299                                 *start_addr++ = *psdm_reg;
300                 case 4:
301                                 *start_addr++ = *psdm_reg;
302                 case 3:
303                                 *start_addr++ = *psdm_reg;
304                 case 2:
305                                 *start_addr++ = *psdm_reg;
306                 case 1:
307                                 *start_addr++ = *psdm_reg;
308                         }
309                 }
310
311                 hades_dma_ctrl |= 1;    /* Set EOP. */
312                 udelay(10);
313                 *start_addr++ = *psdm_reg;
314                 tt_scsi_dma.dma_ctrl &= 0xfd;   /* DMA ready. */
315
316                 set_restdata_reg(start_addr);
317         }
318
319         if (start_addr != end_addr)
320                 printk(KERN_CRIT "DMA emulation: FATAL: Count is not zero at end of transfer.\n");
321
322         dma_cnt = end_addr - start_addr;
323
324 scsi_end:
325         dma_base = (dma_cnt == 0) ? virt_to_phys(start_addr - 1) + 1 :  
326                                     virt_to_phys(start_addr);
327
328         SCSI_DMA_WRITE_P(dma_addr, dma_base);
329         SCSI_DMA_WRITE_P(dma_cnt, dma_cnt);
330
331         /*
332          * Restore old bus error routine.
333          */
334
335         __asm__ __volatile__ ("movec.l  %%vbr,%%a0\n\t"
336                               "move.l   %0,8(%%a0)\n\t"
337                               :
338                               : "r" (save_buserr)
339                               : "a0" );
340
341         atari_enable_irq(IRQ_TT_MFP_SCSI);
342
343         return IRQ_HANDLED;
344
345 scsi_bus_error:
346         /*
347          * First check if the bus error is caused by our code.
348          * If not, call the original handler.
349          */
350
351         __asm__ __volatile__ ("cmp.l    %0,2(%%sp)\n\t"
352                               "bcs.s    .old_vector\n\t"
353                               "cmp.l    %1,2(%%sp)\n\t"
354                               "bls.s    .scsi_buserr\n"
355                         ".old_vector:\n\t"
356                               "move.l   %2,-(%%sp)\n\t"
357                               "rts\n"
358                         ".scsi_buserr:\n\t"
359                               :
360                               : "i" (&&scsi_loop), "i" (&&scsi_end),
361                                 "m" (save_buserr) );
362
363         if (CPU_IS_060)
364         {
365                 /*
366                  * Get effective address and restore the stack.
367                  */
368
369                 __asm__ __volatile__ ("move.l   8(%%sp),%0\n\t"
370                                       "move.l   %1,%%sp\n\t"
371                                       : "=a&" (eff_addr)
372                                       : "r" (save_sp) );
373         }
374         else
375         {
376                 register struct m68040_frame *frame;
377
378                 __asm__ __volatile__ ("lea      8(%%sp),%0\n\t"
379                                       : "=a&" (frame) );
380
381                 if (tt_scsi_dma.dma_ctrl & 1)
382                 {
383                         /*
384                          * Bus error while writing.
385                          */
386
387                         if (frame->wb3s & WBV_040)
388                         {
389                                 if (frame->wb3a == (long) &hades_psdm_reg)
390                                         start_addr--;
391                                 else
392                                         writeback(frame->wb3s, frame->wb3a,
393                                                   frame->wb3d, &&scsi_bus_error);
394                         }
395
396                         if (frame->wb2s & WBV_040)
397                         {
398                                 if (frame->wb2a == (long) &hades_psdm_reg)
399                                         start_addr--;
400                                 else
401                                         writeback(frame->wb2s, frame->wb2a,
402                                                   frame->wb2d, &&scsi_bus_error);
403                         }
404
405                         if (frame->wb1s & WBV_040)
406                         {
407                                 if (frame->wb1a == (long) &hades_psdm_reg)
408                                         start_addr--;
409                         }
410                 }
411                 else
412                 {
413                         /*
414                          * Bus error while reading.
415                          */
416
417                         if (frame->wb3s & WBV_040)
418                                 writeback(frame->wb3s, frame->wb3a,
419                                           frame->wb3d, &&scsi_bus_error);
420                 }
421
422                 eff_addr = (unsigned char *) frame->faddr;
423
424                 __asm__ __volatile__ ("move.l   %0,%%sp\n\t"
425                                       :
426                                       : "r" (save_sp) );
427         }
428
429         dma_cnt = end_addr - start_addr;
430
431         if (eff_addr == &hades_psdm_reg)
432         {
433                 /*
434                  * Bus error occurred while reading the pseudo
435                  * DMA register. Time out.
436                  */
437
438                 tries--;
439
440                 if (tries <= 0)
441                 {
442                         if ((tt_scsi_dma.dma_ctrl & 1) == 0)    /* Read or write? */
443                                 set_restdata_reg(start_addr);
444
445                         if (dma_cnt <= 1)
446                                 printk(KERN_CRIT "DMA emulation: Fatal "
447                                        "error while %s the last byte.\n",
448                                        (tt_scsi_dma.dma_ctrl & 1)
449                                        ? "writing" : "reading");
450
451                         goto scsi_end;
452                 }
453                 else
454                         goto scsi_loop;
455         }
456         else
457         {
458                 /*
459                  * Bus error during pseudo DMA transfer.
460                  * Terminate the DMA transfer.
461                  */
462
463                 hades_dma_ctrl |= 3;    /* Set EOP and bus error. */
464                 if ((tt_scsi_dma.dma_ctrl & 1) == 0)    /* Read or write? */
465                         set_restdata_reg(start_addr);
466                 goto scsi_end;
467         }
468 }