1 /*
2  * Copyright 2014 Advanced Micro Devices, Inc.
3  *
4  * Permission is hereby granted, free of charge, to any person obtaining a
5  * copy of this software and associated documentation files (the "Software"),
6  * to deal in the Software without restriction, including without limitation
7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8  * and/or sell copies of the Software, and to permit persons to whom the
9  * Software is furnished to do so, subject to the following conditions:
10  *
11  * The above copyright notice and this permission notice shall be included in
12  * all copies or substantial portions of the Software.
13  *
14  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
15  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
17  * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
18  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
19  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
20  * OTHER DEALINGS IN THE SOFTWARE.
21  *
22  */
23 #include <drm/drmP.h>
24 #include <drm/amdgpu_drm.h>
25 #include "amdgpu.h"
26 #include "atom.h"
27 #include "atombios_encoders.h"
28 #include "amdgpu_pll.h"
29 #include <asm/div64.h>
30 #include <linux/gcd.h>
31 
32 /**
33  * amdgpu_pll_reduce_ratio - fractional number reduction
34  *
35  * @nom: nominator
36  * @den: denominator
37  * @nom_min: minimum value for nominator
38  * @den_min: minimum value for denominator
39  *
40  * Find the greatest common divisor and apply it on both nominator and
41  * denominator, but make nominator and denominator are at least as large
42  * as their minimum values.
43  */
44 static void amdgpu_pll_reduce_ratio(unsigned *nom, unsigned *den,
45 				    unsigned nom_min, unsigned den_min)
46 {
47 	unsigned tmp;
48 
49 	/* reduce the numbers to a simpler ratio */
50 	tmp = gcd(*nom, *den);
51 	*nom /= tmp;
52 	*den /= tmp;
53 
54 	/* make sure nominator is large enough */
55 	if (*nom < nom_min) {
56 		tmp = DIV_ROUND_UP(nom_min, *nom);
57 		*nom *= tmp;
58 		*den *= tmp;
59 	}
60 
61 	/* make sure the denominator is large enough */
62 	if (*den < den_min) {
63 		tmp = DIV_ROUND_UP(den_min, *den);
64 		*nom *= tmp;
65 		*den *= tmp;
66 	}
67 }
68 
69 /**
70  * amdgpu_pll_get_fb_ref_div - feedback and ref divider calculation
71  *
72  * @nom: nominator
73  * @den: denominator
74  * @post_div: post divider
75  * @fb_div_max: feedback divider maximum
76  * @ref_div_max: reference divider maximum
77  * @fb_div: resulting feedback divider
78  * @ref_div: resulting reference divider
79  *
80  * Calculate feedback and reference divider for a given post divider. Makes
81  * sure we stay within the limits.
82  */
83 static void amdgpu_pll_get_fb_ref_div(unsigned nom, unsigned den, unsigned post_div,
84 				      unsigned fb_div_max, unsigned ref_div_max,
85 				      unsigned *fb_div, unsigned *ref_div)
86 {
87 	/* limit reference * post divider to a maximum */
88 	ref_div_max = min(128 / post_div, ref_div_max);
89 
90 	/* get matching reference and feedback divider */
91 	*ref_div = min(max(DIV_ROUND_CLOSEST(den, post_div), 1u), ref_div_max);
92 	*fb_div = DIV_ROUND_CLOSEST(nom * *ref_div * post_div, den);
93 
94 	/* limit fb divider to its maximum */
95 	if (*fb_div > fb_div_max) {
96 		*ref_div = DIV_ROUND_CLOSEST(*ref_div * fb_div_max, *fb_div);
97 		*fb_div = fb_div_max;
98 	}
99 }
100 
101 /**
102  * amdgpu_pll_compute - compute PLL paramaters
103  *
104  * @pll: information about the PLL
105  * @dot_clock_p: resulting pixel clock
106  * fb_div_p: resulting feedback divider
107  * frac_fb_div_p: fractional part of the feedback divider
108  * ref_div_p: resulting reference divider
109  * post_div_p: resulting reference divider
110  *
111  * Try to calculate the PLL parameters to generate the given frequency:
112  * dot_clock = (ref_freq * feedback_div) / (ref_div * post_div)
113  */
114 void amdgpu_pll_compute(struct amdgpu_pll *pll,
115 			u32 freq,
116 			u32 *dot_clock_p,
117 			u32 *fb_div_p,
118 			u32 *frac_fb_div_p,
119 			u32 *ref_div_p,
120 			u32 *post_div_p)
121 {
122 	unsigned target_clock = pll->flags & AMDGPU_PLL_USE_FRAC_FB_DIV ?
123 		freq : freq / 10;
124 
125 	unsigned fb_div_min, fb_div_max, fb_div;
126 	unsigned post_div_min, post_div_max, post_div;
127 	unsigned ref_div_min, ref_div_max, ref_div;
128 	unsigned post_div_best, diff_best;
129 	unsigned nom, den;
130 
131 	/* determine allowed feedback divider range */
132 	fb_div_min = pll->min_feedback_div;
133 	fb_div_max = pll->max_feedback_div;
134 
135 	if (pll->flags & AMDGPU_PLL_USE_FRAC_FB_DIV) {
136 		fb_div_min *= 10;
137 		fb_div_max *= 10;
138 	}
139 
140 	/* determine allowed ref divider range */
141 	if (pll->flags & AMDGPU_PLL_USE_REF_DIV)
142 		ref_div_min = pll->reference_div;
143 	else
144 		ref_div_min = pll->min_ref_div;
145 
146 	if (pll->flags & AMDGPU_PLL_USE_FRAC_FB_DIV &&
147 	    pll->flags & AMDGPU_PLL_USE_REF_DIV)
148 		ref_div_max = pll->reference_div;
149 	else
150 		ref_div_max = pll->max_ref_div;
151 
152 	/* determine allowed post divider range */
153 	if (pll->flags & AMDGPU_PLL_USE_POST_DIV) {
154 		post_div_min = pll->post_div;
155 		post_div_max = pll->post_div;
156 	} else {
157 		unsigned vco_min, vco_max;
158 
159 		if (pll->flags & AMDGPU_PLL_IS_LCD) {
160 			vco_min = pll->lcd_pll_out_min;
161 			vco_max = pll->lcd_pll_out_max;
162 		} else {
163 			vco_min = pll->pll_out_min;
164 			vco_max = pll->pll_out_max;
165 		}
166 
167 		if (pll->flags & AMDGPU_PLL_USE_FRAC_FB_DIV) {
168 			vco_min *= 10;
169 			vco_max *= 10;
170 		}
171 
172 		post_div_min = vco_min / target_clock;
173 		if ((target_clock * post_div_min) < vco_min)
174 			++post_div_min;
175 		if (post_div_min < pll->min_post_div)
176 			post_div_min = pll->min_post_div;
177 
178 		post_div_max = vco_max / target_clock;
179 		if ((target_clock * post_div_max) > vco_max)
180 			--post_div_max;
181 		if (post_div_max > pll->max_post_div)
182 			post_div_max = pll->max_post_div;
183 	}
184 
185 	/* represent the searched ratio as fractional number */
186 	nom = target_clock;
187 	den = pll->reference_freq;
188 
189 	/* reduce the numbers to a simpler ratio */
190 	amdgpu_pll_reduce_ratio(&nom, &den, fb_div_min, post_div_min);
191 
192 	/* now search for a post divider */
193 	if (pll->flags & AMDGPU_PLL_PREFER_MINM_OVER_MAXP)
194 		post_div_best = post_div_min;
195 	else
196 		post_div_best = post_div_max;
197 	diff_best = ~0;
198 
199 	for (post_div = post_div_min; post_div <= post_div_max; ++post_div) {
200 		unsigned diff;
201 		amdgpu_pll_get_fb_ref_div(nom, den, post_div, fb_div_max,
202 					  ref_div_max, &fb_div, &ref_div);
203 		diff = abs(target_clock - (pll->reference_freq * fb_div) /
204 			(ref_div * post_div));
205 
206 		if (diff < diff_best || (diff == diff_best &&
207 		    !(pll->flags & AMDGPU_PLL_PREFER_MINM_OVER_MAXP))) {
208 
209 			post_div_best = post_div;
210 			diff_best = diff;
211 		}
212 	}
213 	post_div = post_div_best;
214 
215 	/* get the feedback and reference divider for the optimal value */
216 	amdgpu_pll_get_fb_ref_div(nom, den, post_div, fb_div_max, ref_div_max,
217 				  &fb_div, &ref_div);
218 
219 	/* reduce the numbers to a simpler ratio once more */
220 	/* this also makes sure that the reference divider is large enough */
221 	amdgpu_pll_reduce_ratio(&fb_div, &ref_div, fb_div_min, ref_div_min);
222 
223 	/* avoid high jitter with small fractional dividers */
224 	if (pll->flags & AMDGPU_PLL_USE_FRAC_FB_DIV && (fb_div % 10)) {
225 		fb_div_min = max(fb_div_min, (9 - (fb_div % 10)) * 20 + 60);
226 		if (fb_div < fb_div_min) {
227 			unsigned tmp = DIV_ROUND_UP(fb_div_min, fb_div);
228 			fb_div *= tmp;
229 			ref_div *= tmp;
230 		}
231 	}
232 
233 	/* and finally save the result */
234 	if (pll->flags & AMDGPU_PLL_USE_FRAC_FB_DIV) {
235 		*fb_div_p = fb_div / 10;
236 		*frac_fb_div_p = fb_div % 10;
237 	} else {
238 		*fb_div_p = fb_div;
239 		*frac_fb_div_p = 0;
240 	}
241 
242 	*dot_clock_p = ((pll->reference_freq * *fb_div_p * 10) +
243 			(pll->reference_freq * *frac_fb_div_p)) /
244 		       (ref_div * post_div * 10);
245 	*ref_div_p = ref_div;
246 	*post_div_p = post_div;
247 
248 	DRM_DEBUG_KMS("%d - %d, pll dividers - fb: %d.%d ref: %d, post %d\n",
249 		      freq, *dot_clock_p * 10, *fb_div_p, *frac_fb_div_p,
250 		      ref_div, post_div);
251 }
252 
253 /**
254  * amdgpu_pll_get_use_mask - look up a mask of which pplls are in use
255  *
256  * @crtc: drm crtc
257  *
258  * Returns the mask of which PPLLs (Pixel PLLs) are in use.
259  */
260 u32 amdgpu_pll_get_use_mask(struct drm_crtc *crtc)
261 {
262 	struct drm_device *dev = crtc->dev;
263 	struct drm_crtc *test_crtc;
264 	struct amdgpu_crtc *test_amdgpu_crtc;
265 	u32 pll_in_use = 0;
266 
267 	list_for_each_entry(test_crtc, &dev->mode_config.crtc_list, head) {
268 		if (crtc == test_crtc)
269 			continue;
270 
271 		test_amdgpu_crtc = to_amdgpu_crtc(test_crtc);
272 		if (test_amdgpu_crtc->pll_id != ATOM_PPLL_INVALID)
273 			pll_in_use |= (1 << test_amdgpu_crtc->pll_id);
274 	}
275 	return pll_in_use;
276 }
277 
278 /**
279  * amdgpu_pll_get_shared_dp_ppll - return the PPLL used by another crtc for DP
280  *
281  * @crtc: drm crtc
282  *
283  * Returns the PPLL (Pixel PLL) used by another crtc/encoder which is
284  * also in DP mode.  For DP, a single PPLL can be used for all DP
285  * crtcs/encoders.
286  */
287 int amdgpu_pll_get_shared_dp_ppll(struct drm_crtc *crtc)
288 {
289 	struct drm_device *dev = crtc->dev;
290 	struct drm_crtc *test_crtc;
291 	struct amdgpu_crtc *test_amdgpu_crtc;
292 
293 	list_for_each_entry(test_crtc, &dev->mode_config.crtc_list, head) {
294 		if (crtc == test_crtc)
295 			continue;
296 		test_amdgpu_crtc = to_amdgpu_crtc(test_crtc);
297 		if (test_amdgpu_crtc->encoder &&
298 		    ENCODER_MODE_IS_DP(amdgpu_atombios_encoder_get_encoder_mode(test_amdgpu_crtc->encoder))) {
299 			/* for DP use the same PLL for all */
300 			if (test_amdgpu_crtc->pll_id != ATOM_PPLL_INVALID)
301 				return test_amdgpu_crtc->pll_id;
302 		}
303 	}
304 	return ATOM_PPLL_INVALID;
305 }
306 
307 /**
308  * amdgpu_pll_get_shared_nondp_ppll - return the PPLL used by another non-DP crtc
309  *
310  * @crtc: drm crtc
311  * @encoder: drm encoder
312  *
313  * Returns the PPLL (Pixel PLL) used by another non-DP crtc/encoder which can
314  * be shared (i.e., same clock).
315  */
316 int amdgpu_pll_get_shared_nondp_ppll(struct drm_crtc *crtc)
317 {
318 	struct amdgpu_crtc *amdgpu_crtc = to_amdgpu_crtc(crtc);
319 	struct drm_device *dev = crtc->dev;
320 	struct drm_crtc *test_crtc;
321 	struct amdgpu_crtc *test_amdgpu_crtc;
322 	u32 adjusted_clock, test_adjusted_clock;
323 
324 	adjusted_clock = amdgpu_crtc->adjusted_clock;
325 
326 	if (adjusted_clock == 0)
327 		return ATOM_PPLL_INVALID;
328 
329 	list_for_each_entry(test_crtc, &dev->mode_config.crtc_list, head) {
330 		if (crtc == test_crtc)
331 			continue;
332 		test_amdgpu_crtc = to_amdgpu_crtc(test_crtc);
333 		if (test_amdgpu_crtc->encoder &&
334 		    !ENCODER_MODE_IS_DP(amdgpu_atombios_encoder_get_encoder_mode(test_amdgpu_crtc->encoder))) {
335 			/* check if we are already driving this connector with another crtc */
336 			if (test_amdgpu_crtc->connector == amdgpu_crtc->connector) {
337 				/* if we are, return that pll */
338 				if (test_amdgpu_crtc->pll_id != ATOM_PPLL_INVALID)
339 					return test_amdgpu_crtc->pll_id;
340 			}
341 			/* for non-DP check the clock */
342 			test_adjusted_clock = test_amdgpu_crtc->adjusted_clock;
343 			if ((crtc->mode.clock == test_crtc->mode.clock) &&
344 			    (adjusted_clock == test_adjusted_clock) &&
345 			    (amdgpu_crtc->ss_enabled == test_amdgpu_crtc->ss_enabled) &&
346 			    (test_amdgpu_crtc->pll_id != ATOM_PPLL_INVALID))
347 				return test_amdgpu_crtc->pll_id;
348 		}
349 	}
350 	return ATOM_PPLL_INVALID;
351 }
352