path: root/drivers/platform/chrome/cros_ec_proto.c

// SPDX-License-Identifier: GPL-2.0
// ChromeOS EC communication protocol helper functions
//
// Copyright (C) 2015 Google, Inc

#include <linux/delay.h>
#include <linux/device.h>
#include <linux/limits.h>
#include <linux/module.h>
#include <linux/platform_data/cros_ec_commands.h>
#include <linux/platform_data/cros_ec_proto.h>
#include <linux/slab.h>
#include <linux/unaligned.h>

#include "cros_ec_trace.h"

#define EC_COMMAND_RETRIES	50

static const int cros_ec_error_map[] = {
	[EC_RES_INVALID_COMMAND] = -EOPNOTSUPP,
	[EC_RES_ERROR] = -EIO,
	[EC_RES_INVALID_PARAM] = -EINVAL,
	[EC_RES_ACCESS_DENIED] = -EACCES,
	[EC_RES_INVALID_RESPONSE] = -EPROTO,
	[EC_RES_INVALID_VERSION] = -ENOPROTOOPT,
	[EC_RES_INVALID_CHECKSUM] = -EBADMSG,
	[EC_RES_IN_PROGRESS] = -EINPROGRESS,
	[EC_RES_UNAVAILABLE] = -ENODATA,
	[EC_RES_TIMEOUT] = -ETIMEDOUT,
	[EC_RES_OVERFLOW] = -EOVERFLOW,
	[EC_RES_INVALID_HEADER] = -EBADR,
	[EC_RES_REQUEST_TRUNCATED] = -EBADR,
	[EC_RES_RESPONSE_TOO_BIG] = -EFBIG,
	[EC_RES_BUS_ERROR] = -EFAULT,
	[EC_RES_BUSY] = -EBUSY,
	[EC_RES_INVALID_HEADER_VERSION] = -EBADMSG,
	[EC_RES_INVALID_HEADER_CRC] = -EBADMSG,
	[EC_RES_INVALID_DATA_CRC] = -EBADMSG,
	[EC_RES_DUP_UNAVAILABLE] = -ENODATA,
};

static int cros_ec_map_error(uint32_t result)
{
	int ret = 0;

	if (result != EC_RES_SUCCESS) {
		if (result < ARRAY_SIZE(cros_ec_error_map) && cros_ec_error_map[result])
			ret = cros_ec_error_map[result];
		else
			ret = -EPROTO;
	}

	return ret;
}

static int prepare_tx(struct cros_ec_device *ec_dev,
		      struct cros_ec_command *msg)
{
	struct ec_host_request *request;
	u8 *out;
	int i;
	u8 csum = 0;

	if (msg->outsize + sizeof(*request) > ec_dev->dout_size)
		return -EINVAL;

	out = ec_dev->dout;
	request = (struct ec_host_request *)out;
	request->struct_version = EC_HOST_REQUEST_VERSION;
	request->checksum = 0;
	request->command = msg->command;
	request->command_version = msg->version;
	request->reserved = 0;
	request->data_len = msg->outsize;

	for (i = 0; i < sizeof(*request); i++)
		csum += out[i];

	/* Copy data and update checksum */
	memcpy(out + sizeof(*request), msg->data, msg->outsize);
	for (i = 0; i < msg->outsize; i++)
		csum += msg->data[i];

	request->checksum = -csum;

	return sizeof(*request) + msg->outsize;
}

static int prepare_tx_legacy(struct cros_ec_device *ec_dev,
			     struct cros_ec_command *msg)
{
	u8 *out;
	u8 csum;
	int i;

	if (msg->outsize > EC_PROTO2_MAX_PARAM_SIZE)
		return -EINVAL;

	out = ec_dev->dout;
	out[0] = EC_CMD_VERSION0 + msg->version;
	out[1] = msg->command;
	out[2] = msg->outsize;
	csum = out[0] + out[1] + out[2];
	for (i = 0; i < msg->outsize; i++)
		csum += out[EC_MSG_TX_HEADER_BYTES + i] = msg->data[i];
	out[EC_MSG_TX_HEADER_BYTES + msg->outsize] = csum;

	return EC_MSG_TX_PROTO_BYTES + msg->outsize;
}

static int cros_ec_xfer_command(struct cros_ec_device *ec_dev, struct cros_ec_command *msg)
{
	int ret;
	int (*xfer_fxn)(struct cros_ec_device *ec, struct cros_ec_command *msg);

	if (ec_dev->proto_version > 2)
		xfer_fxn = ec_dev->pkt_xfer;
	else
		xfer_fxn = ec_dev->cmd_xfer;

	if (!xfer_fxn) {
		/*
		 * This error can happen if a communication error happened and
		 * the EC is trying to use protocol v2, on an underlying
		 * communication mechanism that does not support v2.
		 */
		dev_err_once(ec_dev->dev, "missing EC transfer API, cannot send command\n");
		return -EIO;
	}

	trace_cros_ec_request_start(msg);
	ret = (*xfer_fxn)(ec_dev, msg);
	trace_cros_ec_request_done(msg