[PATCH v5 2/4] platform/chrome: Add Type C connector class driver

[Prashant Malani]

Add a driver to implement the Type C connector class for Chrome OS
devices with ECs (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".

The driver 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>
Reviewed-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
---

Changes in v5:
- Added Reviewed-by tag which was missed in earlier version.

Changes in v4:
- Added Reviewed-by tag from previous review cycle
- Added code to store port caps within the Cros EC type C data structure
- Added code to use reg to get the port-number in DT platforms.

Changes in v3:
- Fixed minor spacing nits, and moved a modification to probe() if check
  from later patch to here instead.

Changes in v2:
- Updated Kconfig to default to MFD_CROS_EC_DEV.
- Fixed code comments.
- Moved get_num_ports() code into probe().
- Added module author.

 drivers/platform/chrome/Kconfig         |  11 ++
 drivers/platform/chrome/Makefile        |   1 +
 drivers/platform/chrome/cros_ec_typec.c | 238 ++++++++++++++++++++++++
 3 files changed, 250 insertions(+)
 create mode 100644 drivers/platform/chrome/cros_ec_typec.c

diff --git a/drivers/platform/chrome/Kconfig b/drivers/platform/chrome/Kconfig
index 5f57282a28da0..2320a4f0d9301 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 MFD_CROS_EC_DEV && TYPEC
+	default MFD_CROS_EC_DEV
+	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 aacd5920d8a18..caf2a9cdb5e6d 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 0000000000000..02e6d5cbbbf7a
--- /dev/null
+++ b/drivers/platform/chrome/cros_ec_typec.c
@@ -0,0 +1,238 @@
+// 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/module.h>
+#include <linux/of.h>
+#include <linux/platform_data/cros_ec_commands.h>
+#include <linux/platform_data/cros_ec_proto.h>
+#include <linux/platform_device.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];
+	/* Initial capabilities for each port. */
+	struct typec_capability *caps[EC_USB_PD_MAX_PORTS];
+};
+
+static int cros_typec_parse_port_props(struct typec_capability *cap,
+				       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_err(dev, "power-role not found: %d\n", ret);
+		return ret;
+	}
+
+	ret = typec_find_port_power_role(buf);
+	if (ret < 0)
+		return ret;
+	cap->type = ret;
+
+	ret = fwnode_property_read_string(fwnode, "data-role", &buf);
+	if (ret) {
+		dev_err(dev, "data-role not found: %d\n", ret);
+		return ret;
+	}
+
+	ret = typec_find_port_data_role(buf);
+	if (ret < 0)
+		return ret;
+	cap->data = ret;
+
+	ret = fwnode_property_read_string(fwnode, "try-power-role", &buf);
+	if (ret) {
+		dev_err(dev, "try-power-role not found: %d\n", ret);
+		return ret;
+	}
+
+	ret = typec_find_power_role(buf);
+	if (ret < 0)
+		return ret;
+	cap->prefer_role = ret;
+
+	cap->fwnode = fwnode;
+
+	return 0;
+}
+
+static int cros_typec_init_ports(struct cros_typec_data *typec)
+{
+	struct device *dev = typec->dev;
+	struct typec_capability *cap;
+	struct fwnode_handle *fwnode;
+	const char *port_prop;
+	int ret;
+	int i;
+	int nports;
+	u32 port_num = 0;
+
+	nports = device_get_child_node_count(dev);
+	if (nports == 0) {
+		dev_err(dev, "No port entries found.\n");
+		return -ENODEV;
+	}
+
+	if (nports > typec->num_ports) {
+		dev_err(dev, "More ports listed than can be supported.\n");
+		return -EINVAL;
+	}
+
+	/* DT uses "reg" to specify port number. */
+	port_prop = dev->of_node ? "reg" : "port-number";
+	device_for_each_child_node(dev, fwnode) {
+		if (fwnode_property_read_u32(fwnode, port_prop, &port_num)) {
+			ret = -EINVAL;
+			dev_err(dev, "No port-number for port, aborting.\n");
+			goto unregister_ports;
+		}
+
+		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);
+
+		cap = devm_kzalloc(dev, sizeof(*cap), GFP_KERNEL);
+		if (!cap) {
+			ret = -ENOMEM;
+			goto unregister_ports;
+		}
+
+		typec->caps[port_num] = cap;
+
+		ret = cros_typec_parse_port_props(cap, fwnode, dev);
+		if (ret < 0)
+			goto unregister_ports;
+
+		typec->ports[port_num] = typec_register_port(dev, cap);
+		if (IS_ERR(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_ec_command(struct cros_typec_data *typec,
+				 unsigned int version,
+				 unsigned int command,
+				 void *outdata,
+				 unsigned int outsize,
+				 void *indata,
+				 unsigned int insize)
+{
+	struct cros_ec_command *msg;
+	int ret;
+
+	msg = kzalloc(sizeof(*msg) + max(outsize, insize), GFP_KERNEL);
+	if (!msg)
+		return -ENOMEM;
+
+	msg->version = version;
+	msg->command = command;
+	msg->outsize = outsize;
+	msg->insize = insize;
+
+	if (outsize)
+		memcpy(msg->data, outdata, outsize);
+
+	ret = cros_ec_cmd_xfer_status(typec->ec, msg);
+	if (ret >= 0 && insize)
+		memcpy(indata, msg->data, insize);
+
+	kfree(msg);
+	return ret;
+}
+
+#ifdef CONFIG_ACPI
+static const struct acpi_device_id cros_typec_acpi_id[] = {
+	{ "GOOG0014", 0 },
+	{}
+};
+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", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, cros_typec_of_match);
+#endif
+
+static int cros_typec_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct cros_typec_data *typec;
+	struct ec_response_usb_pd_ports resp;
+	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_ec_command(typec, 0, EC_CMD_USB_PD_PORTS, NULL, 0,
+				    &resp, sizeof(resp));
+	if (ret < 0)
+		return ret;
+
+	typec->num_ports = resp.num_ports;
+	if (typec->num_ports > EC_USB_PD_MAX_PORTS) {
+		dev_warn(typec->dev,
+			 "Too many ports reported: %d, limiting to max: %d\n",
+			 typec->num_ports, EC_USB_PD_MAX_PORTS);
+		typec->num_ports = EC_USB_PD_MAX_PORTS;
+	}
+
+	ret = cros_typec_init_ports(typec);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+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_AUTHOR("Prashant Malani <pmalani@xxxxxxxxxxxx>");
+MODULE_DESCRIPTION("Chrome OS EC Type C control");
+MODULE_LICENSE("GPL");
-- 
2.25.1.481.gfbce0eb801-goog