generic: Add a Maxim 98357A codec driver

The Maxim Integrated 98357A codec is an I2S slave device that has no
control channel for configuration and instead provides a GPIO that is
used for channel selection and power down.  This means it does not fit
into a bus hierarchy easily and is instead represented as a generic
device and found with a static bus scan using the devicetree.

This driver provides configuration options for passing the "sdmode" GPIO
descriptor as well as a second option for "sdmode delay" which can
configure the timing of the sdmode toggling in relation to the I2S
channel output.

In addition an GPIO can be provided to indicate to the driver whether
this device is present or not.  This can be used for board designs that
may have different codec possibilities that are selected by HW strap.

Sample usage for this device driver:

device pci 1f.3 on
  chip drivers/generic/max98357a
    register "sdmode_gpio" = "ACPI_GPIO_OUTPUT(GPP_C6)"
    register "sdmode_delay" = "100"
    device generic 0 on end
  end
end

Will result in the following code in the SSDT:

Scope (\_SB.PCI0.HDAS) {
  Device (MAXM) {
    Name (_HID, "MX98357A")
    Name (_UID, Zero)
    Name (_DDN, "Maxim Integrated 98357A Amplifier")
    Method (_STA) { Return (0xF) }
    Name (_CRS, ResourceTemplate () {
      GpioIo (Exclusive, PullDefault, 0, 0, IoRestrictionOutputOnly,
              "\\_SB.PCI0.GPIO", 0, ResourceConsumer)
    })
    Name (_DSD, Package () {
      ToUUID ("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
      Package () {
        Package () { "maxim,sdmode-gpio", \_SB.PCI0.HDAS.MAXM, 0, 0, 0 }
        Package () { "maxim,sdmode-delay", 100 }
        Package () { "sdmode-delay", 100 }
      }
    })
  }
}

Change-Id: Ia0bafe49bea9bbe4a3cc0f9f9cdb6f6390da57b5
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: https://review.coreboot.org/15017
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/drivers/generic/max98357a/Kconfig

@@ -0,0 +1,2 @@
+config DRIVERS_GENERIC_MAX98357A
+	bool

src/drivers/generic/max98357a/Makefile.inc

@@ -0,0 +1 @@
+ramstage-$(CONFIG_DRIVERS_GENERIC_MAX98357A) += max98357a.c

src/drivers/generic/max98357a/chip.h

@@ -0,0 +1,13 @@
+#include <arch/acpi_device.h>
+
+struct drivers_generic_max98357a_config {
+	/* SDMODE GPIO */
+	struct acpi_gpio sdmode_gpio;
+
+	/* SDMODE Delay */
+	unsigned sdmode_delay;
+
+	/* GPIO used to indicate if this device is present */
+	unsigned device_present_gpio;
+	unsigned device_present_gpio_invert;
+};

src/drivers/generic/max98357a/max98357a.c

@@ -0,0 +1,109 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2016 Google Inc.
+ *
+ * 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.
+ */
+
+#include <arch/acpi_device.h>
+#include <arch/acpigen.h>
+#include <console/console.h>
+#include <device/device.h>
+#include <device/path.h>
+#include <gpio.h>
+#include <stdint.h>
+#include <string.h>
+#include "chip.h"
+
+#if IS_ENABLED(CONFIG_HAVE_ACPI_TABLES)
+
+#define MAX98357A_ACPI_NAME	"MAXM"
+#define MAX98357A_ACPI_HID	"MX98357A"
+
+static void max98357a_fill_ssdt(struct device *dev)
+{
+	struct drivers_generic_max98357a_config *config = dev->chip_info;
+	const char *path = acpi_device_path(dev);
+
+	if (!dev->enabled || !path || !config)
+		return;
+
+	/* Device */
+	acpigen_write_scope(acpi_device_scope(dev));
+	acpigen_write_device(acpi_device_name(dev));
+	acpigen_write_name_string("_HID", MAX98357A_ACPI_HID);
+	acpigen_write_name_integer("_UID", 0);
+	acpigen_write_name_string("_DDN", dev->chip_ops->name);
+	acpigen_write_STA(ACPI_STATUS_DEVICE_ALL_ON);
+
+	/* Resources */
+	acpigen_write_name("_CRS");
+	acpigen_write_resourcetemplate_header();
+	acpi_device_write_gpio(&config->sdmode_gpio);
+	acpigen_write_resourcetemplate_footer();
+
+	/* _DSD for devicetree properties */
+	acpi_dp_write_header();
+	/* This points to the first pin in the first gpio entry in _CRS */
+	acpi_dp_write_gpio("maxim,sdmode-gpio", path, 0, 0, 0);
+	/* This is the correctly formatted Device Property name */
+	acpi_dp_write_integer("maxim,sdmode-delay", config->sdmode_delay);
+	/* This is used by the chromium kernel but is not upstream */
+	acpi_dp_write_integer("sdmode-delay", config->sdmode_delay);
+	acpi_dp_write_footer();
+
+	acpigen_pop_len(); /* Device */
+	acpigen_pop_len(); /* Scope */
+
+	printk(BIOS_INFO, "%s: %s\n", path, dev->chip_ops->name);
+}
+
+static const char *max98357a_acpi_name(struct device *dev)
+{
+	return MAX98357A_ACPI_NAME;
+}
+#endif
+
+static struct device_operations max98357a_ops = {
+	.read_resources		  = DEVICE_NOOP,
+	.set_resources		  = DEVICE_NOOP,
+	.enable_resources	  = DEVICE_NOOP,
+#if IS_ENABLED(CONFIG_HAVE_ACPI_TABLES)
+	.acpi_name                = &max98357a_acpi_name,
+	.acpi_fill_ssdt_generator = &max98357a_fill_ssdt,
+#endif
+};
+
+static void max98357a_enable(struct device *dev)
+{
+	struct drivers_generic_max98357a_config *config = dev->chip_info;
+
+	/* Check if device is present by reading GPIO */
+	if (config->device_present_gpio) {
+		int present = gpio_get(config->device_present_gpio);
+		present ^= config->device_present_gpio_invert;
+
+		printk(BIOS_INFO, "%s is %spresent\n",
+		       dev->chip_ops->name, present ? "" : "not ");
+
+		if (!present) {
+			dev->enabled = 0;
+			return;
+		}
+	}
+
+	dev->ops = &max98357a_ops;
+}
+
+struct chip_operations drivers_generic_max98357a_ops = {
+	CHIP_NAME("Maxim Integrated 98357A Amplifier")
+	.enable_dev = &max98357a_enable
+};