platform/chrome: cros_ec: Add EC host command support using rpmsg (2de89fd9) · Commits · e / devices / android_kernel_fairphone_FP5

drivers/platform/chrome/Kconfig

+12 −0

Original line number	Diff line number	Diff line
		@@ -59,6 +59,18 @@ config CROS_EC_I2C
		a checksum. Failing accesses will be retried three times to
		improve reliability.

		config CROS_EC_RPMSG
		tristate "ChromeOS Embedded Controller (rpmsg)"
		depends on MFD_CROS_EC && RPMSG && OF
		help
		If you say Y here, you get support for talking to the ChromeOS EC
		through rpmsg. This uses a simple byte-level protocol with a
		checksum. Also since there's no addition EC-to-host interrupt, this
		use a byte in message to distinguish host event from host command.

		To compile this driver as a module, choose M here: the
		module will be called cros_ec_rpmsg.

		config CROS_EC_SPI
		tristate "ChromeOS Embedded Controller (SPI)"
		depends on MFD_CROS_EC && SPI

drivers/platform/chrome/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -4,6 +4,7 @@ obj-$(CONFIG_CHROMEOS_LAPTOP) += chromeos_laptop.o
		obj-$(CONFIG_CHROMEOS_PSTORE) += chromeos_pstore.o
		obj-$(CONFIG_CHROMEOS_TBMC) += chromeos_tbmc.o
		obj-$(CONFIG_CROS_EC_I2C) += cros_ec_i2c.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_reg.o
		cros_ec_lpcs-$(CONFIG_CROS_EC_LPC_MEC) += cros_ec_lpc_mec.o

drivers/platform/chrome/cros_ec_rpmsg.c

0 → 100644

+258 −0

Original line number	Diff line number	Diff line
		// SPDX-License-Identifier: GPL-2.0
		//
		// Copyright 2018 Google LLC.

		#include <linux/completion.h>
		#include <linux/delay.h>
		#include <linux/kernel.h>
		#include <linux/module.h>
		#include <linux/mfd/cros_ec.h>
		#include <linux/mfd/cros_ec_commands.h>
		#include <linux/of.h>
		#include <linux/platform_device.h>
		#include <linux/rpmsg.h>
		#include <linux/slab.h>

		#define EC_MSG_TIMEOUT_MS 200
		#define HOST_COMMAND_MARK 1
		#define HOST_EVENT_MARK 2

		/**
		* struct cros_ec_rpmsg_response - rpmsg message format from from EC.
		*
		* @type: The type of message, should be either HOST_COMMAND_MARK or
		* HOST_EVENT_MARK, representing that the message is a response to
		* host command, or a host event.
		* @data: ec_host_response for host command.
		*/
		struct cros_ec_rpmsg_response {
		u8 type;
		u8 data[] __aligned(4);
		};

		/**
		* struct cros_ec_rpmsg - information about a EC over rpmsg.
		*
		* @rpdev: rpmsg device we are connected to
		* @xfer_ack: completion for host command transfer.
		* @host_event_work: Work struct for pending host event.
		*/
		struct cros_ec_rpmsg {
		struct rpmsg_device *rpdev;
		struct completion xfer_ack;
		struct work_struct host_event_work;
		};

		/**
		* cros_ec_cmd_xfer_rpmsg - Transfer a message over rpmsg and receive the reply
		*
		* @ec_dev: ChromeOS EC device
		* @ec_msg: Message to transfer
		*
		* This is only used for old EC proto version, and is not supported for this
		* driver.
		*
		* Return: -EINVAL
		*/
		static int cros_ec_cmd_xfer_rpmsg(struct cros_ec_device *ec_dev,
		struct cros_ec_command *ec_msg)
		{
		return -EINVAL;
		}

		/**
		* cros_ec_pkt_xfer_rpmsg - Transfer a packet over rpmsg and receive the reply
		*
		* @ec_dev: ChromeOS EC device
		* @ec_msg: Message to transfer
		*
		* Return: number of bytes of the reply on success or negative error code.
		*/
		static int cros_ec_pkt_xfer_rpmsg(struct cros_ec_device *ec_dev,
		struct cros_ec_command *ec_msg)
		{
		struct cros_ec_rpmsg *ec_rpmsg = ec_dev->priv;
		struct rpmsg_device *rpdev = ec_rpmsg->rpdev;
		struct ec_host_response *response;
		unsigned long timeout;
		int len;
		int ret;
		u8 sum;
		int i;

		ec_msg->result = 0;
		len = cros_ec_prepare_tx(ec_dev, ec_msg);
		dev_dbg(ec_dev->dev, "prepared, len=%d\n", len);

		reinit_completion(&ec_rpmsg->xfer_ack);
		ret = rpmsg_send(rpdev->ept, ec_dev->dout, len);
		if (ret) {
		dev_err(ec_dev->dev, "rpmsg send failed\n");
		return ret;
		}

		timeout = msecs_to_jiffies(EC_MSG_TIMEOUT_MS);
		ret = wait_for_completion_timeout(&ec_rpmsg->xfer_ack, timeout);
		if (!ret) {
		dev_err(ec_dev->dev, "rpmsg send timeout\n");
		return -EIO;
		}

		/* check response error code */
		response = (struct ec_host_response *)ec_dev->din;
		ec_msg->result = response->result;

		ret = cros_ec_check_result(ec_dev, ec_msg);
		if (ret)
		goto exit;

		if (response->data_len > ec_msg->insize) {
		dev_err(ec_dev->dev, "packet too long (%d bytes, expected %d)",
		response->data_len, ec_msg->insize);
		ret = -EMSGSIZE;
		goto exit;
		}

		/* copy response packet payload and compute checksum */
		memcpy(ec_msg->data, ec_dev->din + sizeof(*response),
		response->data_len);

		sum = 0;
		for (i = 0; i < sizeof(*response) + response->data_len; i++)
		sum += ec_dev->din[i];

		if (sum) {
		dev_err(ec_dev->dev, "bad packet checksum, calculated %x\n",
		sum);
		ret = -EBADMSG;
		goto exit;
		}

		ret = response->data_len;
		exit:
		if (ec_msg->command == EC_CMD_REBOOT_EC)
		msleep(EC_REBOOT_DELAY_MS);

		return ret;
		}

		static void
		cros_ec_rpmsg_host_event_function(struct work_struct *host_event_work)
		{
		struct cros_ec_rpmsg *ec_rpmsg = container_of(host_event_work,
		struct cros_ec_rpmsg,
		host_event_work);
		struct cros_ec_device *ec_dev = dev_get_drvdata(&ec_rpmsg->rpdev->dev);
		bool wake_event = true;
		int ret;

		ret = cros_ec_get_next_event(ec_dev, &wake_event);

		/*
		* Signal only if wake host events or any interrupt if
		* cros_ec_get_next_event() returned an error (default value for
		* wake_event is true)
		*/
		if (wake_event && device_may_wakeup(ec_dev->dev))
		pm_wakeup_event(ec_dev->dev, 0);

		if (ret > 0)
		blocking_notifier_call_chain(&ec_dev->event_notifier,
		0, ec_dev);
		}

		static int cros_ec_rpmsg_callback(struct rpmsg_device rpdev, void data,
		int len, void *priv, u32 src)
		{
		struct cros_ec_device *ec_dev = dev_get_drvdata(&rpdev->dev);
		struct cros_ec_rpmsg *ec_rpmsg = ec_dev->priv;
		struct cros_ec_rpmsg_response *resp;

		if (!len) {
		dev_warn(ec_dev->dev, "rpmsg received empty response");
		return -EINVAL;
		}

		resp = data;
		len -= offsetof(struct cros_ec_rpmsg_response, data);
		if (resp->type == HOST_COMMAND_MARK) {
		if (len > ec_dev->din_size) {
		dev_warn(ec_dev->dev,
		"received length %d > din_size %d, truncating",
		len, ec_dev->din_size);
		len = ec_dev->din_size;
		}

		memcpy(ec_dev->din, resp->data, len);
		complete(&ec_rpmsg->xfer_ack);
		} else if (resp->type == HOST_EVENT_MARK) {
		schedule_work(&ec_rpmsg->host_event_work);
		} else {
		dev_warn(ec_dev->dev, "rpmsg received invalid type = %d",
		resp->type);
		return -EINVAL;
		}

		return 0;
		}

		static int cros_ec_rpmsg_probe(struct rpmsg_device *rpdev)
		{
		struct device *dev = &rpdev->dev;
		struct cros_ec_rpmsg *ec_rpmsg;
		struct cros_ec_device *ec_dev;

		ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
		if (!ec_dev)
		return -ENOMEM;

		ec_rpmsg = devm_kzalloc(dev, sizeof(*ec_rpmsg), GFP_KERNEL);
		if (!ec_rpmsg)
		return -ENOMEM;

		ec_dev->dev = dev;
		ec_dev->priv = ec_rpmsg;
		ec_dev->cmd_xfer = cros_ec_cmd_xfer_rpmsg;
		ec_dev->pkt_xfer = cros_ec_pkt_xfer_rpmsg;
		ec_dev->phys_name = dev_name(&rpdev->dev);
		ec_dev->din_size = sizeof(struct ec_host_response) +
		sizeof(struct ec_response_get_protocol_info);
		ec_dev->dout_size = sizeof(struct ec_host_request);
		dev_set_drvdata(dev, ec_dev);

		ec_rpmsg->rpdev = rpdev;
		init_completion(&ec_rpmsg->xfer_ack);
		INIT_WORK(&ec_rpmsg->host_event_work,
		cros_ec_rpmsg_host_event_function);

		return cros_ec_register(ec_dev);
		}

		static void cros_ec_rpmsg_remove(struct rpmsg_device *rpdev)
		{
		struct cros_ec_device *ec_dev = dev_get_drvdata(&rpdev->dev);
		struct cros_ec_rpmsg *ec_rpmsg = ec_dev->priv;

		cancel_work_sync(&ec_rpmsg->host_event_work);
		}

		static const struct of_device_id cros_ec_rpmsg_of_match[] = {
		{ .compatible = "google,cros-ec-rpmsg", },
		{ }
		};
		MODULE_DEVICE_TABLE(of, cros_ec_rpmsg_of_match);

		static struct rpmsg_driver cros_ec_driver_rpmsg = {
		.drv = {
		.name = "cros-ec-rpmsg",
		.of_match_table = cros_ec_rpmsg_of_match,
		},
		.probe = cros_ec_rpmsg_probe,
		.remove = cros_ec_rpmsg_remove,
		.callback = cros_ec_rpmsg_callback,
		};

		module_rpmsg_driver(cros_ec_driver_rpmsg);

		MODULE_LICENSE("GPL v2");
		MODULE_DESCRIPTION("ChromeOS EC multi function device (rpmsg)");