mb/asus/p8z77-m: Support AC97 front audio panel

Add a nvram option for front audio panel type.

If it is set to AC97, reprogram front line out and microphone
pins to match vendor firmware under same configuration.

TEST=On asus/p8z77-m housed in an AOpen H340D case with an AC97
front audio panel, front panel line out port is now available as
headphone port in Fedora 39 with this patch applied and option
set correctly. And it works. Without the patch (or with this option
set to HD Audio), front audio ports are completely inoperable.

Change-Id: I39ccf066d87c5744a697599861719182768e0728
Signed-off-by: Keith Hui <buurin@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/79734
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Nicholas Chin <nic.c3.14@gmail.com>

3 files changed, 42 insertions, 0 deletions

diff --git a/src/mainboard/asus/p8x7x-series/variants/p8z77-m/cmos.default b/src/mainboard/asus/p8x7x-series/variants/p8z77-m/cmos.default
index 3cc854d6c3..79ea560466 100644
--- a/src/mainboard/asus/p8x7x-series/variants/p8z77-m/cmos.default
+++ b/src/mainboard/asus/p8x7x-series/variants/p8z77-m/cmos.default
@@ -9,3 +9,4 @@ sata_mode=AHCI
 usb3_mode=Enable
 usb3_drv=Enable
 usb3_streams=Enable
+audio_panel_type=HDA
diff --git a/src/mainboard/asus/p8x7x-series/variants/p8z77-m/cmos.layout b/src/mainboard/asus/p8x7x-series/variants/p8z77-m/cmos.layout
index 3053b8d913..86bd35a907 100644
--- a/src/mainboard/asus/p8x7x-series/variants/p8z77-m/cmos.layout
+++ b/src/mainboard/asus/p8x7x-series/variants/p8z77-m/cmos.layout
@@ -51,6 +51,11 @@ entries
 #
 424          1       e       1        usb3_streams
 
+# audio_panel_type
+# HD Audio or AC'97
+#
+425          1       e       9        audio_panel_type
+
 # -----------------------------------------------------------------
 # Sandy/Ivy Bridge MRC Scrambler Seed values
 # note: MUST NOT be covered by checksum!
@@ -128,6 +133,10 @@ enumerations
 8     2     Auto
 8     3     SmartAuto
 
+# audio_panel_type
+9     0     HDA
+9     1     AC97
+
 # -----------------------------------------------------------------
 # <startBit[must be byte-aligned]> <endBit[must be byte aligned]>
 #     <bit where to start storing checksum[must be 16bits-aligned]>
diff --git a/src/mainboard/asus/p8x7x-series/variants/p8z77-m/hda_verb.c b/src/mainboard/asus/p8x7x-series/variants/p8z77-m/hda_verb.c
index 738ba53569..b553b17a84 100644
--- a/src/mainboard/asus/p8x7x-series/variants/p8z77-m/hda_verb.c
+++ b/src/mainboard/asus/p8x7x-series/variants/p8z77-m/hda_verb.c
@@ -1,6 +1,9 @@
 /* SPDX-License-Identifier: GPL-2.0-or-later */
 
 #include <device/azalia_device.h>
+#include <stdint.h>
+
+#include <option.h>
 
 const u32 cim_verb_data[] = {
 	0x10ec0887, /* Codec Vendor / Device ID: Realtek */
@@ -34,3 +37,32 @@ const u32 cim_verb_data[] = {
 const u32 pc_beep_verbs[0] = {};
 
 AZALIA_ARRAY_SIZES;
+
+void mainboard_azalia_program_runtime_verbs(u8 *base, u32 viddid)
+{
+	unsigned int ac97 = get_uint_option("audio_panel_type", 0) & 0x1;
+
+	/*
+	 * The verbs above are for a HD Audio front panel.
+	 * With vendor firmware, if audio front panel type is set as AC97, line out 2
+	 * (0x1b) and mic 2 (0x19) pins of ALC887 are configured differently.
+	 *
+	 * The differences are all in the "Misc" fields of configuration defaults (in byte 2)
+	 * as shown below. ALC887 datasheet did not offer details on what those bits
+	 * (listed as reserved in HDA spec) are, so we'll have to take their word for it.
+	 *
+	 * Pin  | 0x19 | 0x1b
+	 * -----+------+-----
+	 * HDA  | 1100 | 1100
+	 * AC97 | 1001 | 0001
+	 */
+
+	const u32 verbs[] = {
+		AZALIA_VERB_12B(0, 0x19, 0x71d, 0x99),
+		AZALIA_VERB_12B(0, 0x1b, 0x71d, 0x41)
+	};
+
+	if ((viddid == 0x10ec0887) && ac97) {
+		azalia_program_verb_table(base, verbs, ARRAY_SIZE(verbs));
+	}
+}