soc/broadwell: set EM4/EM5 registers based on cdclk

The EM4/EM5 registers in the mini-HD audio device must be set based
on the GPU cdclk value in order for HDMI audio to function properly.
Add variables to save the correct values when initializing the GPU,
and accessor functions to retrieve them in order to set the registers
when initializing the mini-HD audio device.

Change-Id: Icce7d5981f0b2ccb09d3861b28b843a260c8aeba
Signed-off-by: Matt DeVillier <matt.devillier@gmail.com>
Reviewed-on: https://review.coreboot.org/17718
Tested-by: build bot (Jenkins)
Reviewed-by: Nico Huber <nico.h@gmx.de>

src/soc/intel/broadwell/igd.c

@@ -31,6 +31,7 @@
 #include <soc/systemagent.h>
 #include <soc/intel/broadwell/chip.h>
 #include <vboot/vbnv.h>
+#include <soc/igd.h>
 
 #define GT_RETRY 		1000
 #define GT_CDCLK_337		0
@@ -38,6 +39,12 @@
 #define GT_CDCLK_540		2
 #define GT_CDCLK_675		3
 
+static u32 reg_em4;
+static u32 reg_em5;
+
+u32 igd_get_reg_em4(void) { return reg_em4; }
+u32 igd_get_reg_em5(void) { return reg_em5; }
+
 struct reg_script haswell_early_init_script[] = {
 	/* Enable Force Wake */
 	REG_RES_WRITE32(PCI_BASE_ADDRESS_0, 0xa180, 0x00000020),
@@ -364,14 +371,20 @@ static void igd_cdclk_init_haswell(struct device *dev)
 	case GT_CDCLK_337:
 		dpdiv = 169;
 		lpcll = (1 << 26);
+		reg_em4 = 16;
+		reg_em5 = 225;
 		break;
 	case GT_CDCLK_450:
 		dpdiv = 225;
 		lpcll = 0;
+		reg_em4 = 4;
+		reg_em5 = 75;
 		break;
 	case GT_CDCLK_540:
 		dpdiv = 270;
 		lpcll = (1 << 26);
+		reg_em4 = 4;
+		reg_em5 = 90;
 		break;
 	default:
 		return;
@@ -432,24 +445,32 @@ static void igd_cdclk_init_broadwell(struct device *dev)
 		lpcll = (1 << 27);
 		pwctl = 2;
 		dpdiv = 169;
+		reg_em4 = 16;
+		reg_em5 = 225;
 		break;
 	case GT_CDCLK_450:
 		cdset = 449;
 		lpcll = 0;
 		pwctl = 0;
 		dpdiv = 225;
+		reg_em4 = 4;
+		reg_em5 = 75;
 		break;
 	case GT_CDCLK_540:
 		cdset = 539;
 		lpcll = (1 << 26);
 		pwctl = 1;
 		dpdiv = 270;
+		reg_em4 = 4;
+		reg_em5 = 90;
 		break;
 	case GT_CDCLK_675:
 		cdset = 674;
 		lpcll = (1 << 26) | (1 << 27);
 		pwctl = 3;
 		dpdiv = 338;
+		reg_em4 = 8;
+		reg_em5 = 225;
 	default:
 		return;
 	}

src/soc/intel/broadwell/include/soc/igd.h

@@ -0,0 +1,20 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef SOC_INTEL_BROADWELL_GMA_H
+#define SOC_INTEL_BROADWELL_GMA_H
+
+u32 igd_get_reg_em4(void);
+u32 igd_get_reg_em5(void);
+
+#endif /* SOC_INTEL_BROADWELL_GMA_H */

src/soc/intel/broadwell/minihd.c

@@ -25,6 +25,7 @@
 #include <stdlib.h>
 #include <soc/intel/common/hda_verb.h>
 #include <soc/ramstage.h>
+#include <soc/igd.h>
 
 static const u32 minihd_verb_table[] = {
 	/* coreboot specific header */
@@ -101,6 +102,10 @@ static void minihd_init(struct device *dev)
 					       minihd_verb_table);
 		}
 	}
+
+	/* Set EM4/EM5 registers */
+	write32(base + 0x0100c, igd_get_reg_em4());
+	write32(base + 0x01010, igd_get_reg_em5());
 }
 
 static struct device_operations minihd_ops = {