1 /* $NetBSD: nouveau_nvkm_subdev_clk_pllgt215.c,v 1.3 2021/12/18 23:45:39 riastradh Exp $ */
2
3 /*
4 * Copyright 2010 Red Hat Inc.
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a
7 * copy of this software and associated documentation files (the "Software"),
8 * to deal in the Software without restriction, including without limitation
9 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
10 * and/or sell copies of the Software, and to permit persons to whom the
11 * Software is furnished to do so, subject to the following conditions:
12 *
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portions of the Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
20 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
21 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
22 * OTHER DEALINGS IN THE SOFTWARE.
23 *
24 * Authors: Ben Skeggs
25 */
26 #include <sys/cdefs.h>
27 __KERNEL_RCSID(0, "$NetBSD: nouveau_nvkm_subdev_clk_pllgt215.c,v 1.3 2021/12/18 23:45:39 riastradh Exp $");
28
29 #include "pll.h"
30
31 #include <subdev/bios.h>
32 #include <subdev/bios/pll.h>
33
34 int
gt215_pll_calc(struct nvkm_subdev * subdev,struct nvbios_pll * info,u32 freq,int * pN,int * pfN,int * pM,int * P)35 gt215_pll_calc(struct nvkm_subdev *subdev, struct nvbios_pll *info,
36 u32 freq, int *pN, int *pfN, int *pM, int *P)
37 {
38 u32 best_err = ~0, err;
39 int M, lM, hM, N, fN;
40
41 *P = info->vco1.max_freq / freq;
42 if (*P > info->max_p)
43 *P = info->max_p;
44 if (*P < info->min_p)
45 *P = info->min_p;
46
47 lM = (info->refclk + info->vco1.max_inputfreq) / info->vco1.max_inputfreq;
48 lM = max(lM, (int)info->vco1.min_m);
49 hM = (info->refclk + info->vco1.min_inputfreq) / info->vco1.min_inputfreq;
50 hM = min(hM, (int)info->vco1.max_m);
51 lM = min(lM, hM);
52
53 for (M = lM; M <= hM; M++) {
54 u32 tmp = freq * *P * M;
55 N = tmp / info->refclk;
56 fN = tmp % info->refclk;
57
58 if (!pfN) {
59 if (fN >= info->refclk / 2)
60 N++;
61 } else {
62 if (fN < info->refclk / 2)
63 N--;
64 fN = tmp - (N * info->refclk);
65 }
66
67 if (N < info->vco1.min_n)
68 continue;
69 if (N > info->vco1.max_n)
70 break;
71
72 err = abs(freq - (info->refclk * N / M / *P));
73 if (err < best_err) {
74 best_err = err;
75 *pN = N;
76 *pM = M;
77 }
78
79 if (pfN) {
80 *pfN = ((fN << 13) + info->refclk / 2) / info->refclk;
81 *pfN = (*pfN - 4096) & 0xffff;
82 return freq;
83 }
84 }
85
86 if (unlikely(best_err == ~0)) {
87 nvkm_error(subdev, "unable to find matching pll values\n");
88 return -EINVAL;
89 }
90
91 return info->refclk * *pN / *pM / *P;
92 }
93