acpi: Add new file for implementing Type-C Connector class

The USB Type-C Connector Class in the Linux kernel is not specific to
the ChromeOS EC, so this functionality is now split out into a separate
file, acpigen_usb.c. Documentation about the kernel side is available at
https://www.kernel.org/doc/html/latest/driver-api/usb/typec.html.

Change-Id: Ife5b8b517b261e7c0068c862ea65039c20382c5a
Signed-off-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/41539
Reviewed-by: Duncan Laurie <dlaurie@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/acpi/Makefile.inc

@@ -6,6 +6,7 @@ ramstage-y += acpi.c
 ramstage-y += acpigen.c
 ramstage-y += acpigen_dsm.c
 ramstage-y += acpigen_ps2_keybd.c
+ramstage-y += acpigen_usb.c
 ramstage-y += device.c
 ramstage-y += pld.c
 ramstage-y += sata.c

src/acpi/acpigen_usb.c

@@ -0,0 +1,136 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include <acpi/acpi.h>
+#include <acpi/acpi_device.h>
+#include <acpi/acpigen.h>
+#include <acpi/acpigen_usb.h>
+
+static const char *power_role_to_str(enum usb_typec_power_role power_role)
+{
+	switch (power_role) {
+	case TYPEC_POWER_ROLE_SOURCE:
+		return "source";
+	case TYPEC_POWER_ROLE_SINK:
+		return "sink";
+	case TYPEC_POWER_ROLE_DUAL:
+		return "dual";
+	default:
+		return "unknown";
+	}
+}
+
+static const char *try_power_role_to_str(enum usb_typec_try_power_role try_power_role)
+{
+	switch (try_power_role) {
+	case TYPEC_TRY_POWER_ROLE_NONE:
+		/*
+		 * This should never get returned; if there is no try-power role for a device,
+		 * then the try-power-role field is not added to the DSD. Thus, this is just
+		 * for completeness.
+		 */
+		return "none";
+	case TYPEC_TRY_POWER_ROLE_SINK:
+		return "sink";
+	case TYPEC_TRY_POWER_ROLE_SOURCE:
+		return "source";
+	default:
+		return "unknown";
+	}
+}
+
+static const char *data_role_to_str(enum usb_typec_data_role data_role)
+{
+	switch (data_role) {
+	case TYPEC_DATA_ROLE_DFP:
+		return "host";
+	case TYPEC_DATA_ROLE_UFP:
+		return "device";
+	case TYPEC_DATA_ROLE_DUAL:
+		return "dual";
+	default:
+		return "unknown";
+	}
+}
+
+/* Add port capabilities as DP properties */
+static void add_port_caps(struct acpi_dp *dsd,
+			  const struct typec_connector_class_config *config)
+{
+	acpi_dp_add_string(dsd, "power-role", power_role_to_str(config->power_role));
+	acpi_dp_add_string(dsd, "data-role", data_role_to_str(config->data_role));
+
+	if (config->try_power_role != TYPEC_TRY_POWER_ROLE_NONE)
+		acpi_dp_add_string(dsd, "try-power-role",
+				   try_power_role_to_str(config->try_power_role));
+}
+
+static void add_device_ref(struct acpi_dp *dsd,
+			   const char *prop_name,
+			   const struct device *dev)
+{
+	const char *path;
+	char *fresh;
+
+	if (!dev)
+		return;
+
+	/*
+	 * Unfortunately, the acpi_dp_* API doesn't write out the data immediately, thus we need
+	 * different storage areas for all of the strings, so strdup() is used for that. It is
+	 * safe to use strdup() here, because the strings are generated at build-time and are
+	 * guaranteed to be NUL-terminated (they come from the devicetree).
+	 */
+	path = acpi_device_path(dev);
+	if (path) {
+		fresh = strdup(path);
+		if (fresh)
+			acpi_dp_add_reference(dsd, prop_name, fresh);
+	}
+}
+
+static void add_device_references(struct acpi_dp *dsd,
+				  const struct typec_connector_class_config *config)
+{
+	/*
+	 * Add references to the USB port objects so that the consumer of this information can
+	 * know whether the port supports USB2, USB3, and/or USB4.
+	 */
+	add_device_ref(dsd, "usb2-port", config->usb2_port);
+	add_device_ref(dsd, "usb3-port", config->usb3_port);
+	add_device_ref(dsd, "usb4-port", config->usb4_port);
+
+	/*
+	 * Add references to the ACPI device(s) which control the orientation, USB data role and
+	 * data muxing.
+	 */
+	add_device_ref(dsd, "orientation-switch", config->orientation_switch);
+	add_device_ref(dsd, "usb-role-switch", config->usb_role_switch);
+	add_device_ref(dsd, "mode-switch", config->mode_switch);
+}
+
+void acpigen_write_typec_connector(const struct typec_connector_class_config *config,
+				   int port_number,
+				   add_custom_dsd_property_cb add_custom_dsd_property)
+{
+	struct acpi_dp *dsd;
+	char name[5];
+
+	/* Create a CONx device */
+	snprintf(name, sizeof(name), "CON%1X", port_number);
+	acpigen_write_device(name);
+	acpigen_write_name_integer("_ADR", port_number);
+
+	dsd = acpi_dp_new_table("_DSD");
+
+	/* Write out the _DSD table */
+	acpi_dp_add_integer(dsd, "port-number", port_number);
+	add_port_caps(dsd, config);
+	add_device_references(dsd, config);
+
+	/* Allow client to add custom properties if desired */
+	if (add_custom_dsd_property)
+		add_custom_dsd_property(dsd, port_number);
+	acpi_dp_write(dsd);
+
+	acpigen_pop_len(); /* Device */
+}

src/include/acpi/acpigen_usb.h

@@ -0,0 +1,61 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#ifndef ACPI_ACPIGEN_USB_H
+#define ACPI_ACPIGEN_USB_H
+
+enum usb_typec_power_role {
+	TYPEC_POWER_ROLE_SOURCE,
+	TYPEC_POWER_ROLE_SINK,
+	TYPEC_POWER_ROLE_DUAL,
+};
+
+enum usb_typec_try_power_role {
+	TYPEC_TRY_POWER_ROLE_NONE,
+	TYPEC_TRY_POWER_ROLE_SINK,
+	TYPEC_TRY_POWER_ROLE_SOURCE,
+};
+
+enum usb_typec_data_role {
+	TYPEC_DATA_ROLE_DFP,
+	TYPEC_DATA_ROLE_UFP,
+	TYPEC_DATA_ROLE_DUAL,
+};
+
+/**
+ * Configuration required to write out a Type-C Connector ACPI object.
+ *
+ * @power_role: DUAL if device supports being both a source and a sink, otherwise choose
+ *	the device's default power role
+ * @try_power_role: SINK if device supports Try.SNK, SOURCE if device supports Try.SRC,
+ *	otherwise choose NONE
+ * @data_role: Choose DUAL if device can alternate between UFP (host) & DFP (device),
+ *	otherwise specify UFP or DFP.
+ * @usb2_port: Reference to the ACPI device that represents the USB2 signals
+ * @usb3_port: Reference to the ACPI device that represents the USB3 signals
+ * @usb4_port: Reference to the ACPI device that represents the USB4 signals
+ * @orientation_switch: Reference to the ACPI device that controls the switching of
+ *	the orientation/polarity for Data and SBU lines.
+ * @usb_role_switch: Reference to the ACPI device that can select the USB role,
+ *	host or device, for the USB port
+ * @mode_switch: Reference to the ACPI device that controls routing of data lines to
+ *	various endpoints (xHCI, DP, etc.) on the SoC.
+ */
+struct typec_connector_class_config {
+	enum usb_typec_power_role power_role;
+	enum usb_typec_try_power_role try_power_role;
+	enum usb_typec_data_role data_role;
+	const struct device *usb2_port;
+	const struct device *usb3_port;
+	const struct device *usb4_port;
+	const struct device *orientation_switch;
+	const struct device *usb_role_switch;
+	const struct device *mode_switch;
+};
+
+typedef void (*add_custom_dsd_property_cb)(struct acpi_dp *dsd, int port_number);
+
+void acpigen_write_typec_connector(const struct typec_connector_class_config *config,
+				   int port_number,
+				   add_custom_dsd_property_cb add_custom_dsd_property);
+
+#endif /* ACPI_ACPIGEN_USB_H */