[RFC 1/3] platform/chrome: Add Type C connector class driver

[Prashant Malani]

Add a the Type C connector class port driver for Chrome OS devices with
an EC (Embedded Controllers).

The driver relies on firmware device specifications for various port
attributes. On ACPI platforms, this is specified using the logical
device with HID GOOG0014. On DT platforms, this is specified using the
DT node with compatible string "google,cros-ec-typec".

This patch reads the device FW node and uses the port attributes to
register the typec ports with the Type C connector class framework, but
doesn't do much else.

Subsequent patches will add more functionality to the driver, including
obtaining current port information (polarity, vconn role, current power
role etc.) after querying the EC.

Signed-off-by: Prashant Malani <pmalani@xxxxxxxxxxxx>
---
 drivers/platform/chrome/Kconfig         |  11 ++
 drivers/platform/chrome/Makefile        |   1 +
 drivers/platform/chrome/cros_ec_typec.c | 198 ++++++++++++++++++++++++
 3 files changed, 210 insertions(+)
 create mode 100644 drivers/platform/chrome/cros_ec_typec.c

diff --git a/drivers/platform/chrome/Kconfig b/drivers/platform/chrome/Kconfig
index 5f57282a28da00..60e3dbd7975aeb 100644
--- a/drivers/platform/chrome/Kconfig
+++ b/drivers/platform/chrome/Kconfig
@@ -214,6 +214,17 @@ config CROS_EC_SYSFS
 	  To compile this driver as a module, choose M here: the
 	  module will be called cros_ec_sysfs.
 
+config CROS_EC_TYPEC
+	tristate "ChromeOS EC Type-C Connector Control"
+	depends on CROS_EC && TYPEC
+	default n
+	help
+	  If you say Y here, you get support for accessing Type C connector
+	  information from the Chrome OS EC.
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called cros_ec_typec.
+
 config CROS_USBPD_LOGGER
 	tristate "Logging driver for USB PD charger"
 	depends on CHARGER_CROS_USBPD
diff --git a/drivers/platform/chrome/Makefile b/drivers/platform/chrome/Makefile
index aacd5920d8a180..caf2a9cdb5e6d1 100644
--- a/drivers/platform/chrome/Makefile
+++ b/drivers/platform/chrome/Makefile
@@ -12,6 +12,7 @@ obj-$(CONFIG_CROS_EC_ISHTP)		+= cros_ec_ishtp.o
 obj-$(CONFIG_CROS_EC_RPMSG)		+= cros_ec_rpmsg.o
 obj-$(CONFIG_CROS_EC_SPI)		+= cros_ec_spi.o
 cros_ec_lpcs-objs			:= cros_ec_lpc.o cros_ec_lpc_mec.o
+obj-$(CONFIG_CROS_EC_TYPEC)		+= cros_ec_typec.o
 obj-$(CONFIG_CROS_EC_LPC)		+= cros_ec_lpcs.o
 obj-$(CONFIG_CROS_EC_PROTO)		+= cros_ec_proto.o cros_ec_trace.o
 obj-$(CONFIG_CROS_KBD_LED_BACKLIGHT)	+= cros_kbd_led_backlight.o
diff --git a/drivers/platform/chrome/cros_ec_typec.c b/drivers/platform/chrome/cros_ec_typec.c
new file mode 100644
index 00000000000000..f48bb0172c565f
--- /dev/null
+++ b/drivers/platform/chrome/cros_ec_typec.c
@@ -0,0 +1,198 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2020 Google LLC
+ *
+ * This driver provides the ability to view and manage Type C ports through the
+ * Chrome OS EC.
+ */
+
+#include <linux/acpi.h>
+#include <linux/mfd/cros_ec.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/platform_data/cros_ec_commands.h>
+#include <linux/platform_data/cros_ec_proto.h>
+#include <linux/usb/typec.h>
+
+#define DRV_NAME "cros-ec-typec"
+
+/* Platform-specific data for the Chrome OS EC Type C controller. */
+struct cros_typec_data {
+	struct device *dev;
+	struct cros_ec_device *ec;
+	int num_ports;
+	/* Array of ports, indexed by port number. */
+	struct typec_port *ports[EC_USB_PD_MAX_PORTS];
+};
+
+void cros_typec_parse_port_props(struct typec_capability *cap,
+				 const struct fwnode_handle *fwnode,
+				 struct device *dev)
+{
+	const char *buf;
+	int ret;
+
+	memset(cap, 0, sizeof(*cap));
+	ret = fwnode_property_read_string(fwnode, "power-role", &buf);
+	if (ret) {
+		dev_warn(dev, "power-role not found: %d\n", ret);
+	} else {
+		if (!strcmp(buf, "source"))
+			cap->type = TYPEC_PORT_SRC;
+		else if (!strcmp(buf, "sink"))
+			cap->type = TYPEC_PORT_SNK;
+		else if (!strcmp(buf, "dual"))
+			cap->type = TYPEC_PORT_DRP;
+		else
+			dev_warn(dev, "Unknown power-role: %s\n", buf);
+	}
+
+	ret = fwnode_property_read_string(fwnode, "data-role", &buf);
+	if (ret) {
+		dev_warn(dev, "data-role not found: %d\n", ret);
+	} else {
+		if (!strcmp(buf, "dfp"))
+			cap->data = TYPEC_PORT_UFP;
+		else if (!strcmp(buf, "ufp"))
+			cap->data = TYPEC_PORT_DFP;
+		else if (!strcmp(buf, "dual"))
+			cap->data = TYPEC_PORT_DRD;
+		else
+			dev_warn(dev, "Unknown data-role: %s\n", buf);
+	}
+
+	ret = fwnode_property_read_string(fwnode, "try-power-role", &buf);
+	if (ret) {
+		dev_warn(dev, "try-power-role not found: %d\n", ret);
+	} else {
+		if (!strcmp(buf, "source"))
+			cap->prefer_role = TYPEC_SOURCE;
+		else if (!strcmp(buf, "sink"))
+			cap->prefer_role = TYPEC_SINK;
+		else
+			dev_warn(dev, "Unknown try-power-role: %s\n", buf);
+	}
+}
+
+static int cros_typec_init_ports(struct cros_typec_data *typec)
+{
+	struct device *dev = typec->dev;
+	struct typec_capability cap;
+	struct fwnode_handle *fwnode;
+	int ret;
+	int i;
+	int nports;
+	u32 port_num;
+
+	nports = device_get_child_node_count(dev);
+	if (nports == 0) {
+		dev_err(dev, "No port entries found.\n");
+		return -ENODEV;
+	}
+
+	device_for_each_child_node(dev, fwnode) {
+		if (fwnode_property_read_u32(fwnode, "port-number",
+					     &port_num)) {
+			dev_warn(dev, "No port-number for port, skipping.\n");
+			continue;
+		}
+
+		if (port_num >= typec->num_ports) {
+			dev_err(dev, "Invalid port number.\n");
+			ret = -EINVAL;
+			goto unregister_ports;
+		}
+
+		dev_dbg(dev, "Registering port %d\n", port_num);
+		cros_typec_parse_port_props(&cap, fwnode, dev);
+		typec->ports[port_num] = typec_register_port(dev, &cap);
+		if (IS_ERR_OR_NULL(typec->ports[port_num])) {
+			dev_err(dev, "Failed to register port %d\n", port_num);
+			ret = PTR_ERR(typec->ports[port_num]);
+			goto unregister_ports;
+		}
+	}
+
+	return 0;
+
+unregister_ports:
+	for (i = 0; i < typec->num_ports; i++)
+		typec_unregister_port(typec->ports[i]);
+	return ret;
+}
+
+static int cros_typec_get_num_ports(struct cros_typec_data *typec)
+{
+	struct ec_response_usb_pd_ports resp;
+	int ret;
+
+	ret = cros_ec_send_cmd_msg(typec->ec, 0, EC_CMD_USB_PD_PORTS, NULL, 0,
+				   &resp, sizeof(resp));
+	if (ret < 0)
+		return ret;
+
+	typec->num_ports = resp.num_ports;
+
+	return 0;
+}
+
+static int cros_typec_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct cros_typec_data *typec;
+	int ret;
+
+	typec = devm_kzalloc(dev, sizeof(*typec), GFP_KERNEL);
+	if (!typec)
+		return -ENOMEM;
+	typec->dev = dev;
+	typec->ec = dev_get_drvdata(pdev->dev.parent);
+	platform_set_drvdata(pdev, typec);
+
+	ret = cros_typec_get_num_ports(typec);
+	if (ret < 0)
+		return ret;
+
+	if (typec->num_ports > EC_USB_PD_MAX_PORTS) {
+		dev_err(dev, "EC reported too many ports. got: %d, max: %d\n",
+			typec->num_ports, EC_USB_PD_MAX_PORTS);
+		return -EOVERFLOW;
+	}
+
+	ret = cros_typec_init_ports(typec);
+	if (!ret)
+		return ret;
+
+	return 0;
+}
+
+#ifdef CONFIG_ACPI
+static const struct acpi_device_id cros_typec_acpi_id[] = {
+	{ "GOOG0014", 0 },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(acpi, cros_typec_acpi_id);
+#endif
+
+#ifdef CONFIG_OF
+static const struct of_device_id cros_typec_of_match[] = {
+	{ .compatible = "google,cros-ec-typec", },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, cros_typec_of_match);
+#endif
+
+static struct platform_driver cros_typec_driver = {
+	.driver	= {
+		.name	= DRV_NAME,
+		.acpi_match_table = ACPI_PTR(cros_typec_acpi_id),
+		.of_match_table = of_match_ptr(cros_typec_of_match),
+	},
+	.probe		= cros_typec_probe,
+};
+
+module_platform_driver(cros_typec_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Chrome OS EC Type C control");
-- 
2.25.0.341.g760bfbb309-goog