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
gt215_pll_calc(struct nvkm_subdev * subdev,struct nvbios_pll * info,u32 freq,int * pN,int * pfN,int * pM,int * P)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 }
88