/* * Copyright 2008 Advanced Micro Devices, Inc. * Copyright 2008 Red Hat Inc. * Copyright 2009 Christian König. * * Permission is hereby granted, free of charge, to any person obtaining a * copy of this software and associated documentation files (the "Software"), * to deal in the Software without restriction, including without limitation * the rights to use, copy, modify, merge, publish, distribute, sublicense, * and/or sell copies of the Software, and to permit persons to whom the * Software is furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR * OTHER DEALINGS IN THE SOFTWARE. * * Authors: Christian König */#include <linux/hdmi.h>#include <linux/gcd.h> #include <drm/amdgpu_drm.h>#include "amdgpu.h" static const struct amdgpu_afmt_acr amdgpu_afmt_predefined_acr[] = {    /*	     32kHz	  44.1kHz	48kHz    */    /* Clock      N     CTS      N     CTS      N     CTS */    {  25175,  4096,  25175, 28224, 125875,  6144,  25175 }, /*  25,20/1.001 MHz */    {  25200,  4096,  25200,  6272,  28000,  6144,  25200 }, /*  25.20       MHz */    {  27000,  4096,  27000,  6272,  30000,  6144,  27000 }, /*  27.00       MHz */    {  27027,  4096,  27027,  6272,  30030,  6144,  27027 }, /*  27.00*1.001 MHz */    {  54000,  4096,  54000,  6272,  60000,  6144,  54000 }, /*  54.00       MHz */    {  54054,  4096,  54054,  6272,  60060,  6144,  54054 }, /*  54.00*1.001 MHz */    {  74176,  4096,  74176,  5733,  75335,  6144,  74176 }, /*  74.25/1.001 MHz */    {  74250,  4096,  74250,  6272,  82500,  6144,  74250 }, /*  74.25       MHz */    { 148352,  4096, 148352,  5733, 150670,  6144, 148352 }, /* 148.50/1.001 MHz */    { 148500,  4096, 148500,  6272, 165000,  6144, 148500 }, /* 148.50       MHz */};  /* * calculate CTS and N values if they are not found in the table */static void amdgpu_afmt_calc_cts(uint32_t clock, int *CTS, int *N, int freq){	int n, cts;	unsigned long div, mul; 	/* Safe, but overly large values */	n = 128 * freq;	cts = clock * 1000; 	/* Smallest valid fraction */	div = gcd(n, cts); 	n /= div;	cts /= div; 	/*	 * The optimal N is 128*freq/1000. Calculate the closest larger	 * value that doesn't truncate any bits.	 */	mul = ((128*freq/1000) + (n-1))/n; 	n *= mul;	cts *= mul; 	/* Check that we are in spec (not always possible) */	if (n < (128*freq/1500))		pr_warn("Calculated ACR N value is too small. You may experience audio problems.\n");	if (n > (128*freq/300))		pr_warn("Calculated ACR N value is too large. You may experience audio problems.\n"); 	*N = n;	*CTS = cts; 	DRM_DEBUG("Calculated ACR timing N=%d CTS=%d for frequency %d\n",		  *N, *CTS, freq);} struct amdgpu_afmt_acr amdgpu_afmt_acr(uint32_t clock){	struct amdgpu_afmt_acr res;	u8 i; 	/* Precalculated values for common clocks */	for (i = 0; i < ARRAY_SIZE(amdgpu_afmt_predefined_acr); i++) {		if (amdgpu_afmt_predefined_acr[i].clock == clock)			return amdgpu_afmt_predefined_acr[i];	} 	/* And odd clocks get manually calculated */	amdgpu_afmt_calc_cts(clock, &res.cts_32khz, &res.n_32khz, 32000);	amdgpu_afmt_calc_cts(clock, &res.cts_44_1khz, &res.n_44_1khz, 44100);	amdgpu_afmt_calc_cts(clock, &res.cts_48khz, &res.n_48khz, 48000);	res.clock = clock; 	return res;}