summaryrefslogtreecommitdiff
path: root/drivers/video/fbdev/aty/mach64_ct.c
blob: 51f29d627cebce988e18b8a535c12db82fe4e09c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649

/*
 *  ATI Mach64 CT/VT/GT/LT Support
 */

#include <linux/fb.h>
#include <linux/delay.h>
#include <asm/io.h>
#include <video/mach64.h>
#include "atyfb.h"
#ifdef CONFIG_PPC
#include <asm/machdep.h>
#endif

#undef DEBUG

static int aty_valid_pll_ct (const struct fb_info *info, u32 vclk_per, struct pll_ct *pll);
static int aty_dsp_gt       (const struct fb_info *info, u32 bpp, struct pll_ct *pll);
static int aty_var_to_pll_ct(const struct fb_info *info, u32 vclk_per, u32 bpp, union aty_pll *pll);
static u32 aty_pll_to_var_ct(const struct fb_info *info, const union aty_pll *pll);

u8 aty_ld_pll_ct(int offset, const struct atyfb_par *par)
{
	u8 res;

	/* write addr byte */
	aty_st_8(CLOCK_CNTL_ADDR, (offset << 2) & PLL_ADDR, par);
	/* read the register value */
	res = aty_ld_8(CLOCK_CNTL_DATA, par);
	return res;
}

static void aty_st_pll_ct(int offset, u8 val, const struct atyfb_par *par)
{
	/* write addr byte */
	aty_st_8(CLOCK_CNTL_ADDR, ((offset << 2) & PLL_ADDR) | PLL_WR_EN, par);
	/* write the register value */
	aty_st_8(CLOCK_CNTL_DATA, val & PLL_DATA, par);
	aty_st_8(CLOCK_CNTL_ADDR, ((offset << 2) & PLL_ADDR) & ~PLL_WR_EN, par);
}

/*
 * by Daniel Mantione
 *                                  <daniel.mantione@freepascal.org>
 *
 *
 * ATI Mach64 CT clock synthesis description.
 *
 * All clocks on the Mach64 can be calculated using the same principle:
 *
 *       XTALIN * x * FB_DIV
 * CLK = ----------------------
 *       PLL_REF_DIV * POST_DIV
 *
 * XTALIN is a fixed speed clock. Common speeds are 14.31 MHz and 29.50 MHz.
 * PLL_REF_DIV can be set by the user, but is the same for all clocks.
 * FB_DIV can be set by the user for each clock individually, it should be set
 * between 128 and 255, the chip will generate a bad clock signal for too low
 * values.
 * x depends on the type of clock; usually it is 2, but for the MCLK it can also
 * be set to 4.
 * POST_DIV can be set by the user for each clock individually, Possible values
 * are 1,2,4,8 and for some clocks other values are available too.
 * CLK is of course the clock speed that is generated.
 *
 * The Mach64 has these clocks:
 *
 * MCLK			The clock rate of the chip
 * XCLK			The clock rate of the on-chip memory
 * VCLK0		First pixel clock of first CRT controller
 * VCLK1    Second pixel clock of first CRT controller
 * VCLK2		Third pixel clock of first CRT controller
 * VCLK3    Fourth pixel clock of first CRT controller
 * VCLK			Selected pixel clock, one of VCLK0, VCLK1, VCLK2, VCLK3
 * V2CLK		Pixel clock of the second CRT controller.
 * SCLK			Multi-purpose clock
 *
 * - MCLK and XCLK use the same FB_DIV
 * - VCLK0 .. VCLK3 use the same FB_DIV
 * - V2CLK is needed when the second CRTC is used (can be used for dualhead);
 *   i.e. CRT monitor connected to laptop has different resolution than built
 *   in LCD monitor.
 * - SCLK is not available on all cards; it is know to exist on the Rage LT-PRO,
 *   Rage XL and Rage Mobility. It is know not to exist on the Mach64 VT.
 * - V2CLK is not available on all cards, most likely only the Rage LT-PRO,
 *   the Rage XL and the Rage Mobility
 *
 * SCLK can be used to:
 * - Clock the chip instead of MCLK
 * - Replace XTALIN with a user defined frequency
 * - Generate the pixel clock for the LCD monitor (instead of VCLK)
 */

 /*
  * It can be quite hard to calculate XCLK and MCLK if they don't run at the
  * same frequency. Luckily, until now all cards that need asynchrone clock
  * speeds seem to have SCLK.
  * So this driver uses SCLK to clock the chip and XCLK to clock the memory.
  */

/* ------------------------------------------------------------------------- */

/*
 *  PLL programming (Mach64 CT family)
 *
 *
 * This procedure sets the display fifo. The display fifo is a buffer that
 * contains data read from the video memory that waits to be processed by
 * the CRT controller.
 *
 * On the more modern Mach64 variants, the chip doesn't calculate the
 * interval after which the display fifo has to be reloaded from memory
 * automatically, the driver has to do it instead.
 */

#define Maximum_DSP_PRECISION 7
static u8 postdividers[] = {1,2,4,8,3};

static int aty_dsp_gt(const struct fb_info *info, u32 bpp, struct pll_ct *pll)
{
	u32 dsp_off, dsp_on, dsp_xclks;
	u32 multiplier, divider, ras_multiplier, ras_divider, tmp;
	u8 vshift, xshift;
	s8 dsp_precision;

	multiplier = ((u32)pll->mclk_fb_div) * pll->vclk_post_div_real;
	divider = ((u32)pll->vclk_fb_div) * pll->xclk_ref_div;

	ras_multiplier = pll->xclkmaxrasdelay;
	ras_divider = 1;

	if (bpp>=8)
		divider = divider * (bpp >> 2);

	vshift = (6 - 2) - pll->xclk_post_div;	/* FIFO is 64 bits wide in accelerator mode ... */

	if (bpp == 0)
		vshift--;	/* ... but only 32 bits in VGA mode. */

#ifdef CONFIG_FB_ATY_GENERIC_LCD
	if (pll->xres != 0) {
		struct atyfb_par *par = (struct atyfb_par *) info->par;

		multiplier = multiplier * par->lcd_width;
		divider = divider * pll->xres & ~7;

		ras_multiplier = ras_multiplier * par->lcd_width;
		ras_divider = ras_divider * pll->xres & ~7;
	}
#endif
	/* If we don't do this, 32 bits for multiplier & divider won't be
	enough in certain situations! */
	while (((multiplier | divider) & 1) == 0) {
		multiplier = multiplier >> 1;
		divider = divider >> 1;
	}

	/* Determine DSP precision first */
	tmp = ((multiplier * pll->fifo_size) << vshift) / divider;

	for (dsp_precision = -5;  tmp;  dsp_precision++)
		tmp >>= 1;
	if (dsp_precision < 0)
		dsp_precision = 0;
	else if (dsp_precision > Maximum_DSP_PRECISION)
		dsp_precision = Maximum_DSP_PRECISION;

	xshift = 6 - dsp_precision;
	vshift += xshift;

	/* Move on to dsp_off */
	dsp_off = ((multiplier * (pll->fifo_size - 1)) << vshift) / divider -
		(1 << (vshift - xshift));

/*    if (bpp == 0)
        dsp_on = ((multiplier * 20 << vshift) + divider) / divider;
    else */
	{
		dsp_on = ((multiplier << vshift) + divider) / divider;
		tmp = ((ras_multiplier << xshift) + ras_divider) / ras_divider;
		if (dsp_on < tmp)
		dsp_on = tmp;
		dsp_on = dsp_on + (tmp * 2) + (pll->xclkpagefaultdelay << xshift);
	}

	/* Calculate rounding factor and apply it to dsp_on */
	tmp = ((1 << (Maximum_DSP_PRECISION - dsp_precision)) - 1) >> 1;
	dsp_on = ((dsp_on + tmp) / (tmp + 1)) * (tmp + 1);

	if (dsp_on >= ((dsp_off / (tmp + 1)) * (tmp + 1))) {
		dsp_on = dsp_off - (multiplier << vshift) / divider;
		dsp_on = (dsp_on / (tmp + 1)) * (tmp + 1);
	}

	/* Last but not least:  dsp_xclks */
	dsp_xclks = ((multiplier << (vshift + 5)) + divider) / divider;

	/* Get register values. */
	pll->dsp_on_off = (dsp_on << 16) + dsp_off;
	pll->dsp_config = (dsp_precision << 20) | (pll->dsp_loop_latency << 16) | dsp_xclks;
#ifdef DEBUG
	printk("atyfb(%s): dsp_config 0x%08x, dsp_on_off 0x%08x\n",
		__func__, pll->dsp_config, pll->dsp_on_off);
#endif
	return 0;
}

static int aty_valid_pll_ct(const struct fb_info *info, u32 vclk_per, struct pll_ct *pll)
{
	u32 q;
	struct atyfb_par *par = (struct atyfb_par *) info->par;
	int pllvclk;

	/* FIXME: use the VTB/GTB /{3,6,12} post dividers if they're better suited */
	q = par->ref_clk_per * pll->pll_ref_div * 4 / vclk_per;
	if (q < 16*8 || q > 255*8) {
		printk(KERN_CRIT "atyfb: vclk out of range\n");
		return -EINVAL;
	} else {
		pll->vclk_post_div  = (q < 128*8);
		pll->vclk_post_div += (q <  64*8);
		pll->vclk_post_div += (q <  32*8);
	}
	pll->vclk_post_div_real = postdividers[pll->vclk_post_div];
	//    pll->vclk_post_div <<= 6;
	pll->vclk_fb_div = q * pll->vclk_post_div_real / 8;
	pllvclk = (1000000 * 2 * pll->vclk_fb_div) /
		(par->ref_clk_per * pll->pll_ref_div);
#ifdef DEBUG
	printk("atyfb(%s): pllvclk=%d MHz, vclk=%d MHz\n",
		__func__, pllvclk, pllvclk / pll->vclk_post_div_real);
#endif
	pll->pll_vclk_cntl = 0x03; /* VCLK = PLL_VCLK/VCLKx_POST */

	/* Set ECP (scaler/overlay clock) divider */
	if (par->pll_limits.ecp_max) {
		int ecp = pllvclk / pll->vclk_post_div_real;
		int ecp_div = 0;

		while (ecp > par->pll_limits.ecp_max && ecp_div < 2) {
			ecp >>= 1;
			ecp_div++;
		}
		pll->pll_vclk_cntl |= ecp_div << 4;
	}

	return 0;
}

static int aty_var_to_pll_ct(const struct fb_info *info, u32 vclk_per, u32 bpp, union aty_pll *pll)
{
	struct atyfb_par *par = (struct atyfb_par *) info->par;
	int err;

	if ((err = aty_valid_pll_ct(info, vclk_per, &pll->ct)))
		return err;
	if (M64_HAS(GTB_DSP) && (err = aty_dsp_gt(info, bpp, &pll->ct)))
		return err;
	/*aty_calc_pll_ct(info, &pll->ct);*/
	return 0;
}

static u32 aty_pll_to_var_ct(const struct fb_info *info, const union aty_pll *pll)
{
	struct atyfb_par *par = (struct atyfb_par *) info->par;
	u32 ret;
	ret = par->ref_clk_per * pll->ct.pll_ref_div * pll->ct.vclk_post_div_real / pll->ct.vclk_fb_div / 2;
#ifdef CONFIG_FB_ATY_GENERIC_LCD
	if(pll->ct.xres > 0) {
		ret *= par->lcd_width;
		ret /= pll->ct.xres;
	}
#endif
#ifdef DEBUG
	printk("atyfb(%s): calculated 0x%08X(%i)\n", __func__, ret, ret);
#endif
	return ret;
}

void aty_set_pll_ct(const struct fb_info *info, const union aty_pll *pll)
{
	struct atyfb_par *par = (struct atyfb_par *) info->par;
	u32 crtc_gen_cntl, lcd_gen_cntrl;
	u8 tmp, tmp2;

	lcd_gen_cntrl = 0;
#ifdef DEBUG
	printk("atyfb(%s): about to program:\n"
		"pll_ext_cntl=0x%02x pll_gen_cntl=0x%02x pll_vclk_cntl=0x%02x\n",
		__func__,
		pll->ct.pll_ext_cntl, pll->ct.pll_gen_cntl, pll->ct.pll_vclk_cntl);

	printk("atyfb(%s): setting clock %lu for FeedBackDivider %i, ReferenceDivider %i, PostDivider %i(%i)\n",
		__func__,
		par->clk_wr_offset, pll->ct.vclk_fb_div,
		pll->ct.pll_ref_div, pll->ct.vclk_post_div, pll->ct.vclk_post_div_real);
#endif
#ifdef CONFIG_FB_ATY_GENERIC_LCD
	if (par->lcd_table != 0) {
		/* turn off LCD */
		lcd_gen_cntrl = aty_ld_lcd(LCD_GEN_CNTL, par);
		aty_st_lcd(LCD_GEN_CNTL, lcd_gen_cntrl & ~LCD_ON, par);
	}
#endif
	aty_st_8(CLOCK_CNTL, par->clk_wr_offset | CLOCK_STROBE, par);

	/* Temporarily switch to accelerator mode */
	crtc_gen_cntl = aty_ld_le32(CRTC_GEN_CNTL, par);
	if (!(crtc_gen_cntl & CRTC_EXT_DISP_EN))
		aty_st_le32(CRTC_GEN_CNTL, crtc_gen_cntl | CRTC_EXT_DISP_EN, par);

	/* Reset VCLK generator */
	aty_st_pll_ct(PLL_VCLK_CNTL, pll->ct.pll_vclk_cntl, par);

	/* Set post-divider */
	tmp2 = par->clk_wr_offset << 1;
	tmp = aty_ld_pll_ct(VCLK_POST_DIV, par);
	tmp &= ~(0x03U << tmp2);
	tmp |= ((pll->ct.vclk_post_div & 0x03U) << tmp2);
	aty_st_pll_ct(VCLK_POST_DIV, tmp, par);

	/* Set extended post-divider */
	tmp = aty_ld_pll_ct(PLL_EXT_CNTL, par);
	tmp &= ~(0x10U << par->clk_wr_offset);
	tmp &= 0xF0U;
	tmp |= pll->ct.pll_ext_cntl;
	aty_st_pll_ct(PLL_EXT_CNTL, tmp, par);

	/* Set feedback divider */
	tmp = VCLK0_FB_DIV + par->clk_wr_offset;
	aty_st_pll_ct(tmp, (pll->ct.vclk_fb_div & 0xFFU), par);

	aty_st_pll_ct(PLL_GEN_CNTL, (pll->ct.pll_gen_cntl & (~(PLL_OVERRIDE | PLL_MCLK_RST))) | OSC_EN, par);

	/* End VCLK generator reset */
	aty_st_pll_ct(PLL_VCLK_CNTL, pll->ct.pll_vclk_cntl & ~(PLL_VCLK_RST), par);
	mdelay(5);

	aty_st_pll_ct(PLL_GEN_CNTL, pll->ct.pll_gen_cntl, par);
	aty_st_pll_ct(PLL_VCLK_CNTL, pll->ct.pll_vclk_cntl, par);
	mdelay(1);

	/* Restore mode register */
	if (!(crtc_gen_cntl & CRTC_EXT_DISP_EN))
		aty_st_le32(CRTC_GEN_CNTL, crtc_gen_cntl, par);

	if (M64_HAS(GTB_DSP)) {
		u8 dll_cntl;

		if (M64_HAS(XL_DLL))
			dll_cntl = 0x80;
		else if (par->ram_type >= SDRAM)
			dll_cntl = 0xa6;
		else
			dll_cntl = 0xa0;
		aty_st_pll_ct(DLL_CNTL, dll_cntl, par);
		aty_st_pll_ct(VFC_CNTL, 0x1b, par);
		aty_st_le32(DSP_CONFIG, pll->ct.dsp_config, par);
		aty_st_le32(DSP_ON_OFF, pll->ct.dsp_on_off, par);

		mdelay(10);
		aty_st_pll_ct(DLL_CNTL, dll_cntl, par);
		mdelay(10);
		aty_st_pll_ct(DLL_CNTL, dll_cntl | 0x40, par);
		mdelay(10);
		aty_st_pll_ct(DLL_CNTL, dll_cntl & ~0x40, par);
	}
#ifdef CONFIG_FB_ATY_GENERIC_LCD
	if (par->lcd_table != 0) {
		/* restore LCD */
		aty_st_lcd(LCD_GEN_CNTL, lcd_gen_cntrl, par);
	}
#endif
}

static void aty_get_pll_ct(const struct fb_info *info, union aty_pll *pll)
{
	struct atyfb_par *par = (struct atyfb_par *) info->par;
	u8 tmp, clock;

	clock = aty_ld_8(CLOCK_CNTL, par) & 0x03U;
	tmp = clock << 1;
	pll->ct.vclk_post_div = (aty_ld_pll_ct(VCLK_POST_DIV, par) >> tmp) & 0x03U;

	pll->ct.pll_ext_cntl = aty_ld_pll_ct(PLL_EXT_CNTL, par) & 0x0FU;
	pll->ct.vclk_fb_div = aty_ld_pll_ct(VCLK0_FB_DIV + clock, par) & 0xFFU;
	pll->ct.pll_ref_div = aty_ld_pll_ct(PLL_REF_DIV, par);
	pll->ct.mclk_fb_div = aty_ld_pll_ct(MCLK_FB_DIV, par);

	pll->ct.pll_gen_cntl = aty_ld_pll_ct(PLL_GEN_CNTL, par);
	pll->ct.pll_vclk_cntl = aty_ld_pll_ct(PLL_VCLK_CNTL, par);

	if (M64_HAS(GTB_DSP)) {
		pll->ct.dsp_config = aty_ld_le32(DSP_CONFIG, par);
		pll->ct.dsp_on_off = aty_ld_le32(DSP_ON_OFF, par);
	}
}

static int aty_init_pll_ct(const struct fb_info *info, union aty_pll *pll)
{
	struct atyfb_par *par = (struct atyfb_par *) info->par;
	u8 mpost_div, xpost_div, sclk_post_div_real;
	u32 q, memcntl, trp;
	u32 dsp_config, dsp_on_off, vga_dsp_config, vga_dsp_on_off;
#ifdef DEBUG
	int pllmclk, pllsclk;
#endif
	pll->ct.pll_ext_cntl = aty_ld_pll_ct(PLL_EXT_CNTL, par);
	pll->ct.xclk_post_div = pll->ct.pll_ext_cntl & 0x07;
	pll->ct.xclk_ref_div = 1;
	switch (pll->ct.xclk_post_div) {
	case 0:  case 1:  case 2:  case 3:
		break;

	case 4:
		pll->ct.xclk_ref_div = 3;
		pll->ct.xclk_post_div = 0;
		break;

	default:
		printk(KERN_CRIT "atyfb: Unsupported xclk source:  %d.\n", pll->ct.xclk_post_div);
		return -EINVAL;
	}
	pll->ct.mclk_fb_mult = 2;
	if(pll->ct.pll_ext_cntl & PLL_MFB_TIMES_4_2B) {
		pll->ct.mclk_fb_mult = 4;
		pll->ct.xclk_post_div -= 1;
	}

#ifdef DEBUG
	printk("atyfb(%s): mclk_fb_mult=%d, xclk_post_div=%d\n",
		__func__, pll->ct.mclk_fb_mult, pll->ct.xclk_post_div);
#endif

	memcntl = aty_ld_le32(MEM_CNTL, par);
	trp = (memcntl & 0x300) >> 8;

	pll->ct.xclkpagefaultdelay = ((memcntl & 0xc00) >> 10) + ((memcntl & 0x1000) >> 12) + trp + 2;
	pll->ct.xclkmaxrasdelay = ((memcntl & 0x70000) >> 16) + trp + 2;

	if (M64_HAS(FIFO_32)) {
		pll->ct.fifo_size = 32;
	} else {
		pll->ct.fifo_size = 24;
		pll->ct.xclkpagefaultdelay += 2;
		pll->ct.xclkmaxrasdelay += 3;
	}

	switch (par->ram_type) {
	case DRAM:
		if (info->fix.smem_len<=ONE_MB) {
			pll->ct.dsp_loop_latency = 10;
		} else {
			pll->ct.dsp_loop_latency = 8;
			pll->ct.xclkpagefaultdelay += 2;
		}
		break;
	case EDO:
	case PSEUDO_EDO:
		if (info->fix.smem_len<=ONE_MB) {
			pll->ct.dsp_loop_latency = 9;
		} else {
			pll->ct.dsp_loop_latency = 8;
			pll->ct.xclkpagefaultdelay += 1;
		}
		break;
	case SDRAM:
		if (info->fix.smem_len<=ONE_MB) {
			pll->ct.dsp_loop_latency = 11;
		} else {
			pll->ct.dsp_loop_latency = 10;
			pll->ct.xclkpagefaultdelay += 1;
		}
		break;
	case SGRAM:
		pll->ct.dsp_loop_latency = 8;
		pll->ct.xclkpagefaultdelay += 3;
		break;
	default:
		pll->ct.dsp_loop_latency = 11;
		pll->ct.xclkpagefaultdelay += 3;
		break;
	}

	if (pll->ct.xclkmaxrasdelay <= pll->ct.xclkpagefaultdelay)
		pll->ct.xclkmaxrasdelay = pll->ct.xclkpagefaultdelay + 1;

	/* Allow BIOS to override */
	dsp_config = aty_ld_le32(DSP_CONFIG, par);
	dsp_on_off = aty_ld_le32(DSP_ON_OFF, par);
	vga_dsp_config = aty_ld_le32(VGA_DSP_CONFIG, par);
	vga_dsp_on_off = aty_ld_le32(VGA_DSP_ON_OFF, par);

	if (dsp_config)
		pll->ct.dsp_loop_latency = (dsp_config & DSP_LOOP_LATENCY) >> 16;
#if 0
	FIXME: is it relevant for us?
	if ((!dsp_on_off && !M64_HAS(RESET_3D)) ||
		((dsp_on_off == vga_dsp_on_off) &&
		(!dsp_config || !((dsp_config ^ vga_dsp_config) & DSP_XCLKS_PER_QW)))) {
		vga_dsp_on_off &= VGA_DSP_OFF;
		vga_dsp_config &= VGA_DSP_XCLKS_PER_QW;
		if (ATIDivide(vga_dsp_on_off, vga_dsp_config, 5, 1) > 24)
			pll->ct.fifo_size = 32;
		else
			pll->ct.fifo_size = 24;
	}
#endif
	/* Exit if the user does not want us to tamper with the clock
	rates of her chip. */
	if (par->mclk_per == 0) {
		u8 mclk_fb_div, pll_ext_cntl;
		pll->ct.pll_ref_div = aty_ld_pll_ct(PLL_REF_DIV, par);
		pll_ext_cntl = aty_ld_pll_ct(PLL_EXT_CNTL, par);
		pll->ct.xclk_post_div_real = postdividers[pll_ext_cntl & 0x07];
		mclk_fb_div = aty_ld_pll_ct(MCLK_FB_DIV, par);
		if (pll_ext_cntl & PLL_MFB_TIMES_4_2B)
			mclk_fb_div <<= 1;
		pll->ct.mclk_fb_div = mclk_fb_div;
		return 0;
	}

	pll->ct.pll_ref_div = par->pll_per * 2 * 255 / par->ref_clk_per;

	/* FIXME: use the VTB/GTB /3 post divider if it's better suited */
	q = par->ref_clk_per * pll->ct.pll_ref_div * 8 /
		(pll->ct.mclk_fb_mult * par->xclk_per);

	if (q < 16*8 || q > 255*8) {
		printk(KERN_CRIT "atxfb: xclk out of range\n");
		return -EINVAL;
	} else {
		xpost_div  = (q < 128*8);
		xpost_div += (q <  64*8);
		xpost_div += (q <  32*8);
	}
	pll->ct.xclk_post_div_real = postdividers[xpost_div];
	pll->ct.mclk_fb_div = q * pll->ct.xclk_post_div_real / 8;

#ifdef CONFIG_PPC
	if (machine_is(powermac)) {
		/* Override PLL_EXT_CNTL & 0x07. */
		pll->ct.xclk_post_div = xpost_div;
		pll->ct.xclk_ref_div = 1;
	}
#endif

#ifdef DEBUG
	pllmclk = (1000000 * pll->ct.mclk_fb_mult * pll->ct.mclk_fb_div) /
			(par->ref_clk_per * pll->ct.pll_ref_div);
	printk("atyfb(%s): pllmclk=%d MHz, xclk=%d MHz\n",
		__func__, pllmclk, pllmclk / pll->ct.xclk_post_div_real);
#endif

	if (M64_HAS(SDRAM_MAGIC_PLL) && (par->ram_type >= SDRAM))
		pll->ct.pll_gen_cntl = OSC_EN;
	else
		pll->ct.pll_gen_cntl = OSC_EN | DLL_PWDN /* | FORCE_DCLK_TRI_STATE */;

	if (M64_HAS(MAGIC_POSTDIV))
		pll->ct.pll_ext_cntl = 0;
	else
		pll->ct.pll_ext_cntl = xpost_div;

	if (pll->ct.mclk_fb_mult == 4)
		pll->ct.pll_ext_cntl |= PLL_MFB_TIMES_4_2B;

	if (par->mclk_per == par->xclk_per) {
		pll->ct.pll_gen_cntl |= (xpost_div << 4); /* mclk == xclk */
	} else {
		/*
		* The chip clock is not equal to the memory clock.
		* Therefore we will use sclk to clock the chip.
		*/
		pll->ct.pll_gen_cntl |= (6 << 4); /* mclk == sclk */

		q = par->ref_clk_per * pll->ct.pll_ref_div * 4 / par->mclk_per;
		if (q < 16*8 || q > 255*8) {
			printk(KERN_CRIT "atyfb: mclk out of range\n");
			return -EINVAL;
		} else {
			mpost_div  = (q < 128*8);
			mpost_div += (q <  64*8);
			mpost_div += (q <  32*8);
		}
		sclk_post_div_real = postdividers[mpost_div];
		pll->ct.sclk_fb_div = q * sclk_post_div_real / 8;
		pll->ct.spll_cntl2 = mpost_div << 4;
#ifdef DEBUG
		pllsclk = (1000000 * 2 * pll->ct.sclk_fb_div) /
			(par->ref_clk_per * pll->ct.pll_ref_div);
		printk("atyfb(%s): use sclk, pllsclk=%d MHz, sclk=mclk=%d MHz\n",
			__func__, pllsclk, pllsclk / sclk_post_div_real);
#endif
	}

	/* Disable the extra precision pixel clock controls since we do not use them. */
	pll->ct.ext_vpll_cntl = aty_ld_pll_ct(EXT_VPLL_CNTL, par);
	pll->ct.ext_vpll_cntl &= ~(EXT_VPLL_EN | EXT_VPLL_VGA_EN | EXT_VPLL_INSYNC);

	return 0;
}

static void aty_resume_pll_ct(const struct fb_info *info,
			      union aty_pll *pll)
{
	struct atyfb_par *par = info->par;

	if (par->mclk_per != par->xclk_per) {
		/*
		* This disables the sclk, crashes the computer as reported:
		* aty_st_pll_ct(SPLL_CNTL2, 3, info);
		*
		* So it seems the sclk must be enabled before it is used;
		* so PLL_GEN_CNTL must be programmed *after* the sclk.
		*/
		aty_st_pll_ct(SCLK_FB_DIV, pll->ct.sclk_fb_div, par);
		aty_st_pll_ct(SPLL_CNTL2, pll->ct.spll_cntl2, par);
		/*
		 * SCLK has been started. Wait for the PLL to lock. 5 ms
		 * should be enough according to mach64 programmer's guide.
		 */
		mdelay(5);
	}

	aty_st_pll_ct(PLL_REF_DIV, pll->ct.pll_ref_div, par);
	aty_st_pll_ct(PLL_GEN_CNTL, pll->ct.pll_gen_cntl, par);
	aty_st_pll_ct(MCLK_FB_DIV, pll->ct.mclk_fb_div, par);
	aty_st_pll_ct(PLL_EXT_CNTL, pll->ct.pll_ext_cntl, par);
	aty_st_pll_ct(EXT_VPLL_CNTL, pll->ct.ext_vpll_cntl, par);
}

static int dummy(void)
{
	return 0;
}

const struct aty_dac_ops aty_dac_ct = {
	.set_dac	= (void *) dummy,
};

const struct aty_pll_ops aty_pll_ct = {
	.var_to_pll	= aty_var_to_pll_ct,
	.pll_to_var	= aty_pll_to_var_ct,
	.set_pll	= aty_set_pll_ct,
	.get_pll	= aty_get_pll_ct,
	.init_pll	= aty_init_pll_ct,
	.resume_pll	= aty_resume_pll_ct,
};