drivers/usb: Add chip driver for external USB hub

Add chip driver for soldered down external USB hub. This driver adds
ACPI objects for the hub and any downstream facing ports.

BUG=b:227761300
TEST=Build and boot to OS in Skyrim. Ensure that the hub and any
configured ports have ACPI devices defined in SSDT.

Signed-off-by: Karthikeyan Ramasubramanian <kramasub@google.com>
Change-Id: I11d7ccc42d3dce8e136eb771f120825980e5c027
Reviewed-on: https://review.coreboot.org/c/coreboot/+/63968
Reviewed-by: Raul Rangel <rrangel@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/drivers/usb/hub/Kconfig

@@ -0,0 +1,8 @@
+config DRIVERS_USB_HUB
+	bool
+	default n
+	depends on HAVE_ACPI_TABLES
+	help
+	   This driver is for soldered down USB Hub in the mainboard. When enabled,
+	   this driver will add ACPI support for the USB hub and any devices on the
+	   downstream facing ports.

src/drivers/usb/hub/Makefile.inc

@@ -0,0 +1 @@
+ramstage-$(CONFIG_DRIVERS_USB_HUB) += acpi.c

src/drivers/usb/hub/acpi.c

@@ -0,0 +1,88 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include <acpi/acpigen.h>
+#include <acpi/acpi_device.h>
+#include <stdlib.h>
+
+#include "chip.h"
+
+static const char *usb_hub_acpi_name(const struct device *dev)
+{
+	char *name;
+	const char *pattern;
+
+	/* USB ACPI driver does not have acpi_name operation defined. Hence return
+	   the ACPI name for both the hub and any downstream facing ports. */
+	switch (dev->path.usb.port_type) {
+	case 0:
+		return "EHUB";
+	case 2:
+		pattern = "HS%02d";
+		break;
+	case 3:
+		pattern = "SS%02d";
+		break;
+	default:
+		return NULL;
+	}
+
+	name = malloc(ACPI_NAME_BUFFER_SIZE);
+	snprintf(name, ACPI_NAME_BUFFER_SIZE, pattern, dev->path.usb.port_id + 1);
+	name[4] = '\0';
+
+	return name;
+}
+
+static void usb_hub_add_ports(const struct device *dev)
+{
+	const struct drivers_usb_hub_config *config = config_of(dev);
+	struct device *port = NULL;
+	unsigned int child_count = 0;
+
+	while ((port = dev_bus_each_child(dev->link_list, port)) != NULL) {
+		if (child_count++ >= config->port_count) {
+			printk(BIOS_WARNING, "%s cannot be added. Port Count limit reached.\n",
+			       dev_name(port));
+			continue;
+		}
+		acpigen_write_device(usb_hub_acpi_name(port));
+		acpigen_write_name_byte("_ADR", port->path.usb.port_id + 1);
+		acpigen_write_device_end();
+	}
+}
+
+static void usb_hub_acpi_fill_ssdt(const struct device *dev)
+{
+	const struct drivers_usb_hub_config *config = config_of(dev);
+	const char *scope = acpi_device_scope(dev);
+	const char *name = acpi_device_name(dev);
+
+	acpigen_write_scope(scope);
+	acpigen_write_device(name);
+	acpigen_write_ADR(0);
+	if (config->name)
+		acpigen_write_name_string("_DDN", config->name);
+	if (config->desc)
+		acpigen_write_name_unicode("_STR", config->desc);
+	usb_hub_add_ports(dev);
+	acpigen_write_device_end();
+	acpigen_write_scope_end();
+}
+
+static struct device_operations usb_hub_ops = {
+	.read_resources	= noop_read_resources,
+	.set_resources	= noop_set_resources,
+	.scan_bus	= scan_static_bus,
+	.acpi_fill_ssdt	= usb_hub_acpi_fill_ssdt,
+	.acpi_name	= usb_hub_acpi_name
+};
+
+static void usb_hub_acpi_enable(struct device *dev)
+{
+	dev->ops = &usb_hub_ops;
+}
+
+struct chip_operations drivers_usb_hub_ops = {
+	 CHIP_NAME("USB Hub")
+	.enable_dev = usb_hub_acpi_enable
+};

src/drivers/usb/hub/chip.h

@@ -0,0 +1,12 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef __DRIVERS_USB_HUB_CHIP_H__
+#define __DRIVERS_USB_HUB_CHIP_H__
+
+struct drivers_usb_hub_config {
+	const char *name;
+	const char *desc;
+	unsigned int port_count; /* Number of Super-speed or High-speed ports */
+};
+
+#endif /* __DRIVERS_USB_HUB_CHIP_H__ */