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
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 */
44static 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(a: *nom, b: *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 * @adev: amdgpu_device pointer
73 * @nom: nominator
74 * @den: denominator
75 * @post_div: post divider
76 * @fb_div_max: feedback divider maximum
77 * @ref_div_max: reference divider maximum
78 * @fb_div: resulting feedback divider
79 * @ref_div: resulting reference divider
80 *
81 * Calculate feedback and reference divider for a given post divider. Makes
82 * sure we stay within the limits.
83 */
84static void amdgpu_pll_get_fb_ref_div(struct amdgpu_device *adev, unsigned int nom,
85 unsigned int den, unsigned int post_div,
86 unsigned int fb_div_max, unsigned int ref_div_max,
87 unsigned int *fb_div, unsigned int *ref_div)
88{
89
90 /* limit reference * post divider to a maximum */
91 if (adev->family == AMDGPU_FAMILY_SI)
92 ref_div_max = min(100 / post_div, ref_div_max);
93 else
94 ref_div_max = min(128 / post_div, ref_div_max);
95
96 /* get matching reference and feedback divider */
97 *ref_div = clamp(DIV_ROUND_CLOSEST(den, post_div), 1u, ref_div_max);
98 *fb_div = DIV_ROUND_CLOSEST(nom * *ref_div * post_div, den);
99
100 /* limit fb divider to its maximum */
101 if (*fb_div > fb_div_max) {
102 *ref_div = DIV_ROUND_CLOSEST(*ref_div * fb_div_max, *fb_div);
103 *fb_div = fb_div_max;
104 }
105}
106
107/**
108 * amdgpu_pll_compute - compute PLL paramaters
109 *
110 * @adev: amdgpu_device pointer
111 * @pll: information about the PLL
112 * @freq: requested frequency
113 * @dot_clock_p: resulting pixel clock
114 * @fb_div_p: resulting feedback divider
115 * @frac_fb_div_p: fractional part of the feedback divider
116 * @ref_div_p: resulting reference divider
117 * @post_div_p: resulting reference divider
118 *
119 * Try to calculate the PLL parameters to generate the given frequency:
120 * dot_clock = (ref_freq * feedback_div) / (ref_div * post_div)
121 */
122void amdgpu_pll_compute(struct amdgpu_device *adev,
123 struct amdgpu_pll *pll,
124 u32 freq,
125 u32 *dot_clock_p,
126 u32 *fb_div_p,
127 u32 *frac_fb_div_p,
128 u32 *ref_div_p,
129 u32 *post_div_p)
130{
131 unsigned target_clock = pll->flags & AMDGPU_PLL_USE_FRAC_FB_DIV ?
132 freq : freq / 10;
133
134 unsigned fb_div_min, fb_div_max, fb_div;
135 unsigned post_div_min, post_div_max, post_div;
136 unsigned ref_div_min, ref_div_max, ref_div;
137 unsigned post_div_best, diff_best;
138 unsigned nom, den;
139
140 /* determine allowed feedback divider range */
141 fb_div_min = pll->min_feedback_div;
142 fb_div_max = pll->max_feedback_div;
143
144 if (pll->flags & AMDGPU_PLL_USE_FRAC_FB_DIV) {
145 fb_div_min *= 10;
146 fb_div_max *= 10;
147 }
148
149 /* determine allowed ref divider range */
150 if (pll->flags & AMDGPU_PLL_USE_REF_DIV)
151 ref_div_min = pll->reference_div;
152 else
153 ref_div_min = pll->min_ref_div;
154
155 if (pll->flags & AMDGPU_PLL_USE_FRAC_FB_DIV &&
156 pll->flags & AMDGPU_PLL_USE_REF_DIV)
157 ref_div_max = pll->reference_div;
158 else
159 ref_div_max = pll->max_ref_div;
160
161 /* determine allowed post divider range */
162 if (pll->flags & AMDGPU_PLL_USE_POST_DIV) {
163 post_div_min = pll->post_div;
164 post_div_max = pll->post_div;
165 } else {
166 unsigned vco_min, vco_max;
167
168 if (pll->flags & AMDGPU_PLL_IS_LCD) {
169 vco_min = pll->lcd_pll_out_min;
170 vco_max = pll->lcd_pll_out_max;
171 } else {
172 vco_min = pll->pll_out_min;
173 vco_max = pll->pll_out_max;
174 }
175
176 if (pll->flags & AMDGPU_PLL_USE_FRAC_FB_DIV) {
177 vco_min *= 10;
178 vco_max *= 10;
179 }
180
181 post_div_min = vco_min / target_clock;
182 if ((target_clock * post_div_min) < vco_min)
183 ++post_div_min;
184 if (post_div_min < pll->min_post_div)
185 post_div_min = pll->min_post_div;
186
187 post_div_max = vco_max / target_clock;
188 if ((target_clock * post_div_max) > vco_max)
189 --post_div_max;
190 if (post_div_max > pll->max_post_div)
191 post_div_max = pll->max_post_div;
192 }
193
194 /* represent the searched ratio as fractional number */
195 nom = target_clock;
196 den = pll->reference_freq;
197
198 /* reduce the numbers to a simpler ratio */
199 amdgpu_pll_reduce_ratio(nom: &nom, den: &den, nom_min: fb_div_min, den_min: post_div_min);
200
201 /* now search for a post divider */
202 if (pll->flags & AMDGPU_PLL_PREFER_MINM_OVER_MAXP)
203 post_div_best = post_div_min;
204 else
205 post_div_best = post_div_max;
206 diff_best = ~0;
207
208 for (post_div = post_div_min; post_div <= post_div_max; ++post_div) {
209 unsigned diff;
210 amdgpu_pll_get_fb_ref_div(adev, nom, den, post_div, fb_div_max,
211 ref_div_max, fb_div: &fb_div, ref_div: &ref_div);
212 diff = abs(target_clock - (pll->reference_freq * fb_div) /
213 (ref_div * post_div));
214
215 if (diff < diff_best || (diff == diff_best &&
216 !(pll->flags & AMDGPU_PLL_PREFER_MINM_OVER_MAXP))) {
217
218 post_div_best = post_div;
219 diff_best = diff;
220 }
221 }
222 post_div = post_div_best;
223
224 /* get the feedback and reference divider for the optimal value */
225 amdgpu_pll_get_fb_ref_div(adev, nom, den, post_div, fb_div_max, ref_div_max,
226 fb_div: &fb_div, ref_div: &ref_div);
227
228 /* reduce the numbers to a simpler ratio once more */
229 /* this also makes sure that the reference divider is large enough */
230 amdgpu_pll_reduce_ratio(nom: &fb_div, den: &ref_div, nom_min: fb_div_min, den_min: ref_div_min);
231
232 /* avoid high jitter with small fractional dividers */
233 if (pll->flags & AMDGPU_PLL_USE_FRAC_FB_DIV && (fb_div % 10)) {
234 fb_div_min = max(fb_div_min, (9 - (fb_div % 10)) * 20 + 60);
235 if (fb_div < fb_div_min) {
236 unsigned tmp = DIV_ROUND_UP(fb_div_min, fb_div);
237 fb_div *= tmp;
238 ref_div *= tmp;
239 }
240 }
241
242 /* and finally save the result */
243 if (pll->flags & AMDGPU_PLL_USE_FRAC_FB_DIV) {
244 *fb_div_p = fb_div / 10;
245 *frac_fb_div_p = fb_div % 10;
246 } else {
247 *fb_div_p = fb_div;
248 *frac_fb_div_p = 0;
249 }
250
251 *dot_clock_p = ((pll->reference_freq * *fb_div_p * 10) +
252 (pll->reference_freq * *frac_fb_div_p)) /
253 (ref_div * post_div * 10);
254 *ref_div_p = ref_div;
255 *post_div_p = post_div;
256
257 DRM_DEBUG_KMS("%d - %d, pll dividers - fb: %d.%d ref: %d, post %d\n",
258 freq, *dot_clock_p * 10, *fb_div_p, *frac_fb_div_p,
259 ref_div, post_div);
260}
261
262/**
263 * amdgpu_pll_get_use_mask - look up a mask of which pplls are in use
264 *
265 * @crtc: drm crtc
266 *
267 * Returns the mask of which PPLLs (Pixel PLLs) are in use.
268 */
269u32 amdgpu_pll_get_use_mask(struct drm_crtc *crtc)
270{
271 struct drm_device *dev = crtc->dev;
272 struct drm_crtc *test_crtc;
273 struct amdgpu_crtc *test_amdgpu_crtc;
274 u32 pll_in_use = 0;
275
276 list_for_each_entry(test_crtc, &dev->mode_config.crtc_list, head) {
277 if (crtc == test_crtc)
278 continue;
279
280 test_amdgpu_crtc = to_amdgpu_crtc(test_crtc);
281 if (test_amdgpu_crtc->pll_id != ATOM_PPLL_INVALID)
282 pll_in_use |= (1 << test_amdgpu_crtc->pll_id);
283 }
284 return pll_in_use;
285}
286
287/**
288 * amdgpu_pll_get_shared_dp_ppll - return the PPLL used by another crtc for DP
289 *
290 * @crtc: drm crtc
291 *
292 * Returns the PPLL (Pixel PLL) used by another crtc/encoder which is
293 * also in DP mode. For DP, a single PPLL can be used for all DP
294 * crtcs/encoders.
295 */
296int amdgpu_pll_get_shared_dp_ppll(struct drm_crtc *crtc)
297{
298 struct drm_device *dev = crtc->dev;
299 struct drm_crtc *test_crtc;
300 struct amdgpu_crtc *test_amdgpu_crtc;
301
302 list_for_each_entry(test_crtc, &dev->mode_config.crtc_list, head) {
303 if (crtc == test_crtc)
304 continue;
305 test_amdgpu_crtc = to_amdgpu_crtc(test_crtc);
306 if (test_amdgpu_crtc->encoder &&
307 ENCODER_MODE_IS_DP(amdgpu_atombios_encoder_get_encoder_mode(test_amdgpu_crtc->encoder))) {
308 /* for DP use the same PLL for all */
309 if (test_amdgpu_crtc->pll_id != ATOM_PPLL_INVALID)
310 return test_amdgpu_crtc->pll_id;
311 }
312 }
313 return ATOM_PPLL_INVALID;
314}
315
316/**
317 * amdgpu_pll_get_shared_nondp_ppll - return the PPLL used by another non-DP crtc
318 *
319 * @crtc: drm crtc
320 *
321 * Returns the PPLL (Pixel PLL) used by another non-DP crtc/encoder which can
322 * be shared (i.e., same clock).
323 */
324int amdgpu_pll_get_shared_nondp_ppll(struct drm_crtc *crtc)
325{
326 struct amdgpu_crtc *amdgpu_crtc = to_amdgpu_crtc(crtc);
327 struct drm_device *dev = crtc->dev;
328 struct drm_crtc *test_crtc;
329 struct amdgpu_crtc *test_amdgpu_crtc;
330 u32 adjusted_clock, test_adjusted_clock;
331
332 adjusted_clock = amdgpu_crtc->adjusted_clock;
333
334 if (adjusted_clock == 0)
335 return ATOM_PPLL_INVALID;
336
337 list_for_each_entry(test_crtc, &dev->mode_config.crtc_list, head) {
338 if (crtc == test_crtc)
339 continue;
340 test_amdgpu_crtc = to_amdgpu_crtc(test_crtc);
341 if (test_amdgpu_crtc->encoder &&
342 !ENCODER_MODE_IS_DP(amdgpu_atombios_encoder_get_encoder_mode(test_amdgpu_crtc->encoder))) {
343 /* check if we are already driving this connector with another crtc */
344 if (test_amdgpu_crtc->connector == amdgpu_crtc->connector) {
345 /* if we are, return that pll */
346 if (test_amdgpu_crtc->pll_id != ATOM_PPLL_INVALID)
347 return test_amdgpu_crtc->pll_id;
348 }
349 /* for non-DP check the clock */
350 test_adjusted_clock = test_amdgpu_crtc->adjusted_clock;
351 if ((crtc->mode.clock == test_crtc->mode.clock) &&
352 (adjusted_clock == test_adjusted_clock) &&
353 (amdgpu_crtc->ss_enabled == test_amdgpu_crtc->ss_enabled) &&
354 (test_amdgpu_crtc->pll_id != ATOM_PPLL_INVALID))
355 return test_amdgpu_crtc->pll_id;
356 }
357 }
358 return ATOM_PPLL_INVALID;
359}
360

source code of linux/drivers/gpu/drm/amd/amdgpu/amdgpu_pll.c