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
29int
30gt215_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