1/*
2 * Copyright 2008 Advanced Micro Devices, Inc.
3 * Copyright 2008 Red Hat Inc.
4 * Copyright 2009 Christian K��nig.
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: Christian K��nig
25 */
26#include <linux/hdmi.h>
27#include <linux/gcd.h>
28#include <drm/drmP.h>
29#include <drm/amdgpu_drm.h>
30#include "amdgpu.h"
31
32static const struct amdgpu_afmt_acr amdgpu_afmt_predefined_acr[] = {
33    /*	     32kHz	  44.1kHz	48kHz    */
34    /* Clock      N     CTS      N     CTS      N     CTS */
35    {  25175,  4096,  25175, 28224, 125875,  6144,  25175 }, /*  25,20/1.001 MHz */
36    {  25200,  4096,  25200,  6272,  28000,  6144,  25200 }, /*  25.20       MHz */
37    {  27000,  4096,  27000,  6272,  30000,  6144,  27000 }, /*  27.00       MHz */
38    {  27027,  4096,  27027,  6272,  30030,  6144,  27027 }, /*  27.00*1.001 MHz */
39    {  54000,  4096,  54000,  6272,  60000,  6144,  54000 }, /*  54.00       MHz */
40    {  54054,  4096,  54054,  6272,  60060,  6144,  54054 }, /*  54.00*1.001 MHz */
41    {  74176,  4096,  74176,  5733,  75335,  6144,  74176 }, /*  74.25/1.001 MHz */
42    {  74250,  4096,  74250,  6272,  82500,  6144,  74250 }, /*  74.25       MHz */
43    { 148352,  4096, 148352,  5733, 150670,  6144, 148352 }, /* 148.50/1.001 MHz */
44    { 148500,  4096, 148500,  6272, 165000,  6144, 148500 }, /* 148.50       MHz */
45};
46
47
48/*
49 * calculate CTS and N values if they are not found in the table
50 */
51static void amdgpu_afmt_calc_cts(uint32_t clock, int *CTS, int *N, int freq)
52{
53	int n, cts;
54	unsigned long div, mul;
55
56	/* Safe, but overly large values */
57	n = 128 * freq;
58	cts = clock * 1000;
59
60	/* Smallest valid fraction */
61	div = gcd(n, cts);
62
63	n /= div;
64	cts /= div;
65
66	/*
67	 * The optimal N is 128*freq/1000. Calculate the closest larger
68	 * value that doesn't truncate any bits.
69	 */
70	mul = ((128*freq/1000) + (n-1))/n;
71
72	n *= mul;
73	cts *= mul;
74
75	/* Check that we are in spec (not always possible) */
76	if (n < (128*freq/1500))
77		printk(KERN_WARNING "Calculated ACR N value is too small. You may experience audio problems.\n");
78	if (n > (128*freq/300))
79		printk(KERN_WARNING "Calculated ACR N value is too large. You may experience audio problems.\n");
80
81	*N = n;
82	*CTS = cts;
83
84	DRM_DEBUG("Calculated ACR timing N=%d CTS=%d for frequency %d\n",
85		  *N, *CTS, freq);
86}
87
88struct amdgpu_afmt_acr amdgpu_afmt_acr(uint32_t clock)
89{
90	struct amdgpu_afmt_acr res;
91	u8 i;
92
93	/* Precalculated values for common clocks */
94	for (i = 0; i < ARRAY_SIZE(amdgpu_afmt_predefined_acr); i++) {
95		if (amdgpu_afmt_predefined_acr[i].clock == clock)
96			return amdgpu_afmt_predefined_acr[i];
97	}
98
99	/* And odd clocks get manually calculated */
100	amdgpu_afmt_calc_cts(clock, &res.cts_32khz, &res.n_32khz, 32000);
101	amdgpu_afmt_calc_cts(clock, &res.cts_44_1khz, &res.n_44_1khz, 44100);
102	amdgpu_afmt_calc_cts(clock, &res.cts_48khz, &res.n_48khz, 48000);
103
104	return res;
105}
106