1 /*
2 * Copyright 2010 Red Hat 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 * Authors: Ben Skeggs
23 */
24 #include "pll.h"
25
26 #include <subdev/bios.h>
27 #include <subdev/bios/pll.h>
28
29 int
30 gt215_pll_calc(struct nvkm_subdev *subdev, struct nvbios_pll *info,
31 u32 freq, int *pN, int *pfN, int *pM, int *P)
32 {
33 u32 best_err = ~0, err;
34 int M, lM, hM, N, fN;
35
36 *P = info->vco1.max_freq / freq;
37 if (*P > info->max_p)
38 *P = info->max_p;
39 if (*P < info->min_p)
40 *P = info->min_p;
41
42 lM = (info->refclk + info->vco1.max_inputfreq) / info->vco1.max_inputfreq;
43 lM = max(lM, (int)info->vco1.min_m);
44 hM = (info->refclk + info->vco1.min_inputfreq) / info->vco1.min_inputfreq;
45 hM = min(hM, (int)info->vco1.max_m);
46 lM = min(lM, hM);
47
48 for (M = lM; M <= hM; M++) {
49 u32 tmp = freq * *P * M;
50 N = tmp / info->refclk;
51 fN = tmp % info->refclk;
52
53 if (!pfN) {
54 if (fN >= info->refclk / 2)
55 N++;
56 } else {
57 if (fN < info->refclk / 2)
58 N--;
59 fN = tmp - (N * info->refclk);
60 }
61
62 if (N < info->vco1.min_n)
63 continue;
64 if (N > info->vco1.max_n)
65 break;
66
67 err = abs(freq - (info->refclk * N / M / *P));
68 if (err < best_err) {
69 best_err = err;
70 *pN = N;
71 *pM = M;
72 }
73
74 if (pfN) {
75 *pfN = ((fN << 13) + info->refclk / 2) / info->refclk;
76 *pfN = (*pfN - 4096) & 0xffff;
77 return freq;
78 }
79 }
80
81 if (unlikely(best_err == ~0)) {
82 nvkm_error(subdev, "unable to find matching pll values\n");
83 return -EINVAL;
84 }
85
86 return info->refclk * *pN / *pM / *P;
87 }