ec/google/chromeec: Add driver for audio codec device

This change adds driver for audio codec device (HID `GOOG0013`) living
behind Chrome EC. This driver generates the required ACPI node for the
codec device. In a later change, GOOG0013 device will be dropped
the .asl file.

Change-Id: Ib2759eac60265ef81df70af1d4f1f72bd9d987e8
Signed-off-by: Furquan Shaikh <furquan@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/43041
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/ec/google/chromeec/Makefile.inc

@@ -1,5 +1,6 @@
 ifeq ($(CONFIG_EC_GOOGLE_CHROMEEC),y)
 
+subdirs-y += audio_codec
 subdirs-y += i2c_tunnel
 
 bootblock-$(CONFIG_EC_GOOGLE_CHROMEEC_BOARDID) += ec_boardid.c

src/ec/google/chromeec/audio_codec/Kconfig

@@ -0,0 +1,10 @@
+if EC_GOOGLE_CHROMEEC
+
+config EC_GOOGLE_CHROMEEC_AUDIO_CODEC
+	bool
+	depends on HAVE_ACPI_TABLES
+	help
+	  This enables the Cros EC audio codec driver that is required to fill the
+	  SSDT nodes for the codec device used by the mainboard.
+
+endif

src/ec/google/chromeec/audio_codec/Makefile.inc

@@ -0,0 +1 @@
+ramstage-$(CONFIG_EC_GOOGLE_CHROMEEC_AUDIO_CODEC) += audio_codec.c

src/ec/google/chromeec/audio_codec/audio_codec.c

@@ -0,0 +1,64 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include <acpi/acpi_device.h>
+#include <acpi/acpigen.h>
+#include <console/console.h>
+#include <device/device.h>
+#include <device/path.h>
+#include "chip.h"
+
+#define CROS_EC_AUDIO_CODEC_HID		"GOOG0013"
+#define CROS_EC_AUDIO_CODEC_DDN		"Cros EC audio codec"
+
+static void crosec_audio_codec_fill_ssdt(const struct device *dev)
+{
+	const char *scope = acpi_device_scope(dev);
+	struct ec_google_chromeec_audio_codec_config *cfg = dev->chip_info;
+
+	if (!dev->enabled || !scope || !cfg)
+		return;
+
+	acpigen_write_scope(scope);
+
+	acpigen_write_device(acpi_device_name(dev));
+	acpigen_write_name_string("_HID", CROS_EC_AUDIO_CODEC_HID);
+	acpigen_write_name_integer("_UID", cfg->uid);
+	acpigen_write_name_string("_DDN", CROS_EC_AUDIO_CODEC_DDN);
+	acpigen_write_STA(acpi_device_status(dev));
+
+	acpigen_pop_len(); /* Device */
+	acpigen_pop_len(); /* Scope */
+
+	printk(BIOS_INFO, "%s: %s at %s\n", acpi_device_path(dev), CROS_EC_AUDIO_CODEC_DDN,
+						dev_path(dev));
+}
+
+static const char *crosec_audio_codec_acpi_name(const struct device *dev)
+{
+	struct ec_google_chromeec_audio_codec_config *cfg = dev->chip_info;
+	static char name[5];
+
+	if (cfg->name)
+		return cfg->name;
+
+	snprintf(name, sizeof(name), "ECA%X", dev->path.generic.id);
+	return name;
+}
+
+static struct device_operations crosec_audio_codec_ops = {
+	.read_resources		= noop_read_resources,
+	.set_resources		= noop_set_resources,
+	.acpi_name		= crosec_audio_codec_acpi_name,
+	.acpi_fill_ssdt		= crosec_audio_codec_fill_ssdt,
+	.scan_bus		= scan_static_bus,
+};
+
+static void crosec_audio_codec_enable(struct device *dev)
+{
+	dev->ops = &crosec_audio_codec_ops;
+}
+
+struct chip_operations ec_google_chromeec_audio_codec_ops = {
+	CHIP_NAME("CrosEC Audio Codec Device")
+	.enable_dev = crosec_audio_codec_enable
+};

src/ec/google/chromeec/audio_codec/chip.h

@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#ifndef __EC_GOOGLE_CHROMEEC_AUDIO_CODEC__
+#define __EC_GOOGLE_CHROMEEC_AUDIO_CODEC__
+
+struct ec_google_chromeec_audio_codec_config {
+	/* ACPI device name */
+	const char *name;
+	/* ACPI _UID */
+	unsigned int uid;
+};
+
+#endif /* __EC_GOOGLE_CHROMEEC_AUDIO_CODEC__ */