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1da177e4 LT |
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 | ||
8c65b4a6 TS |
22 | #include <linux/compiler.h> |
23 | #include <asm/thread_info.h> | |
1da177e4 LT |
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 | /* | |
7d12e780 | 113 | * void hades_dma_emulator(int irq, void *dummy) |
1da177e4 LT |
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 | ||
7d12e780 | 143 | static irqreturn_t hades_dma_emulator(int irq, void *dummy) |
1da177e4 LT |
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 | } |