sound: Add an ACPI driver for Maxim MAX98357ac

This chip is used on coral and we need to generate ACPI tables for sound
to make it work. Add a driver that does just this (i.e. at present does
not actually support playing sound).

Signed-off-by: Simon Glass <sjg@chromium.org>
[bmeng: Use the correct acpi_irq_polarity enum number]
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>

configs/sandbox_defconfig

@@ -211,6 +211,7 @@ CONFIG_SMEM=y
 CONFIG_SANDBOX_SMEM=y
 CONFIG_SOUND=y
 CONFIG_SOUND_DA7219=y
+CONFIG_SOUND_MAX98357A=y
 CONFIG_SOUND_SANDBOX=y
 CONFIG_SANDBOX_SPI=y
 CONFIG_SPMI=y

doc/device-tree-bindings/sound/max98357a.txt

@@ -0,0 +1,22 @@
+Maxim MAX98357A audio DAC
+
+This node models the Maxim MAX98357A DAC.
+
+Required properties:
+- compatible   : "maxim,max98357a"
+
+Optional properties:
+- sdmode-gpios : GPIO specifier for the chip's SD_MODE pin.
+        If this option is not specified then driver does not manage
+        the pin state (e.g. chip is always on).
+- sdmode-delay : specify delay time for SD_MODE pin.
+        If this option is specified, which means it's required i2s clocks
+        ready before SD_MODE is unmuted in order to avoid the speaker pop noise.
+        It's observed that 5ms is sufficient.
+
+Example:
+
+max98357a {
+	compatible = "maxim,max98357a";
+	sdmode-gpios = <&qcom_pinmux 25 0>;
+};

drivers/sound/Kconfig

@@ -113,6 +113,15 @@ config SOUND_MAX98095
 	  audio data and I2C for codec control. At present it only works
 	  with the Samsung I2S driver.
 
+config SOUND_MAX98357A
+	bool "Support Maxim max98357a audio codec"
+	depends on PCI
+	help
+	  Enable the max98357a audio codec. This is connected on PCI for
+	  audio data codec control. This is currently only capable of providing
+	  ACPI information. A full driver (with sound in U-Boot) is currently
+	  not available.
+
 config SOUND_RT5677
 	bool "Support Realtek RT5677 audio codec"
 	depends on SOUND

drivers/sound/Makefile

@@ -17,6 +17,7 @@ obj-$(CONFIG_SOUND_WM8994)	+= wm8994.o
 obj-$(CONFIG_SOUND_MAX98088)	+= max98088.o maxim_codec.o
 obj-$(CONFIG_SOUND_MAX98090)	+= max98090.o maxim_codec.o
 obj-$(CONFIG_SOUND_MAX98095)	+= max98095.o maxim_codec.o
+obj-$(CONFIG_SOUND_MAX98357A)	+= max98357a.o
 obj-$(CONFIG_SOUND_INTEL_HDA)	+= hda_codec.o
 obj-$(CONFIG_SOUND_I8254)	+= i8254_beep.o
 obj-$(CONFIG_SOUND_RT5677)	+= rt5677.o

drivers/sound/max98357a.c

@@ -0,0 +1,161 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * max98357a.c -- MAX98357A Audio driver
+ *
+ * Copyright 2019 Google LLC
+ * Parts taken from coreboot
+ */
+
+#include <common.h>
+#include <audio_codec.h>
+#include <dm.h>
+#include <log.h>
+#include <sound.h>
+#include <acpi/acpigen.h>
+#include <acpi/acpi_device.h>
+#include <acpi/acpi_dp.h>
+#include <asm-generic/gpio.h>
+#ifdef CONFIG_X86
+#include <asm/acpi_nhlt.h>
+#endif
+#include <dt-bindings/sound/nhlt.h>
+#include <dm/acpi.h>
+
+struct max98357a_priv {
+	struct gpio_desc sdmode_gpio;
+};
+
+static int max98357a_ofdata_to_platdata(struct udevice *dev)
+{
+	struct max98357a_priv *priv = dev_get_priv(dev);
+	int ret;
+
+	ret = gpio_request_by_name(dev, "sdmode-gpios", 0, &priv->sdmode_gpio,
+				   GPIOD_IS_IN);
+	if (ret)
+		return log_msg_ret("gpio", ret);
+
+	return 0;
+}
+
+static int max98357a_acpi_fill_ssdt(const struct udevice *dev,
+				    struct acpi_ctx *ctx)
+{
+	struct max98357a_priv *priv = dev_get_priv(dev);
+	char scope[ACPI_PATH_MAX];
+	char name[ACPI_NAME_MAX];
+	char path[ACPI_PATH_MAX];
+	struct acpi_dp *dp;
+	int ret;
+
+	ret = acpi_device_scope(dev, scope, sizeof(scope));
+	if (ret)
+		return log_msg_ret("scope", ret);
+	ret = acpi_get_name(dev, name);
+	if (ret)
+		return log_msg_ret("name", ret);
+
+	/* Device */
+	acpigen_write_scope(ctx, scope);
+	acpigen_write_device(ctx, name);
+	acpigen_write_name_string(ctx, "_HID",
+				  dev_read_string(dev, "acpi,hid"));
+	acpigen_write_name_integer(ctx, "_UID", 0);
+	acpigen_write_name_string(ctx, "_DDN",
+				  dev_read_string(dev, "acpi,ddn"));
+	acpigen_write_sta(ctx, acpi_device_status(dev));
+
+	/* Resources */
+	acpigen_write_name(ctx, "_CRS");
+	acpigen_write_resourcetemplate_header(ctx);
+	ret = acpi_device_write_gpio_desc(ctx, &priv->sdmode_gpio);
+	if (ret)
+		return log_msg_ret("gpio", ret);
+	acpigen_write_resourcetemplate_footer(ctx);
+
+	/* _DSD for devicetree properties */
+	/* This points to the first pin in the first gpio entry in _CRS */
+	ret = acpi_device_path(dev, path, sizeof(path));
+	if (ret)
+		return log_msg_ret("path", ret);
+	dp = acpi_dp_new_table("_DSD");
+	acpi_dp_add_gpio(dp, "sdmode-gpio", path, 0, 0,
+			 priv->sdmode_gpio.flags & GPIOD_ACTIVE_LOW ?
+			 ACPI_IRQ_ACTIVE_LOW : ACPI_IRQ_ACTIVE_HIGH);
+	acpi_dp_add_integer(dp, "sdmode-delay",
+			    dev_read_u32_default(dev, "sdmode-delay", 0));
+	acpi_dp_write(ctx, dp);
+
+	acpigen_pop_len(ctx); /* Device */
+	acpigen_pop_len(ctx); /* Scope */
+
+	return 0;
+}
+
+/* For now only X86 boards support NHLT */
+#ifdef CONFIG_X86
+static const struct nhlt_format_config max98357a_formats[] = {
+	/* 48 KHz 24-bits per sample. */
+	{
+		.num_channels = 2,
+		.sample_freq_khz = 48,
+		.container_bits_per_sample = 32,
+		.valid_bits_per_sample = 24,
+		.settings_file = "max98357-render-2ch-48khz-24b.dat",
+	},
+};
+
+static const struct nhlt_endp_descriptor max98357a_descriptors[] = {
+	{
+		.link = NHLT_LINK_SSP,
+		.device = NHLT_SSP_DEV_I2S,
+		.direction = NHLT_DIR_RENDER,
+		.vid = NHLT_VID,
+		.did = NHLT_DID_SSP,
+		.formats = max98357a_formats,
+		.num_formats = ARRAY_SIZE(max98357a_formats),
+	},
+};
+
+static int max98357a_acpi_setup_nhlt(const struct udevice *dev,
+				     struct acpi_ctx *ctx)
+{
+	u32 hwlink;
+	int ret;
+
+	if (dev_read_u32(dev, "acpi,audio-link", &hwlink))
+		return log_msg_ret("link", -EINVAL);
+
+	/* Virtual bus id of SSP links are the hardware port ids proper. */
+	ret = nhlt_add_ssp_endpoints(ctx->nhlt, hwlink, max98357a_descriptors,
+				     ARRAY_SIZE(max98357a_descriptors));
+	if (ret)
+		return log_msg_ret("add", ret);
+
+	return 0;
+}
+#endif
+
+struct acpi_ops max98357a_acpi_ops = {
+	.fill_ssdt	= max98357a_acpi_fill_ssdt,
+#ifdef CONFIG_X86
+	.setup_nhlt	= max98357a_acpi_setup_nhlt,
+#endif
+};
+
+static const struct audio_codec_ops max98357a_ops = {
+};
+
+static const struct udevice_id max98357a_ids[] = {
+	{ .compatible = "maxim,max98357a" },
+	{ }
+};
+
+U_BOOT_DRIVER(max98357a) = {
+	.name		= "max98357a",
+	.id		= UCLASS_AUDIO_CODEC,
+	.of_match	= max98357a_ids,
+	.ofdata_to_platdata	= max98357a_ofdata_to_platdata,
+	.ops		= &max98357a_ops,
+	ACPI_OPS_PTR(&max98357a_acpi_ops)
+};