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/* SPDX-License-Identifier: GPL-2.0-only */
/* This file is part of the coreboot project. */
#include <console/console.h>
#include <stdint.h>
#include <string.h>
#include "ec.h"
#include "ec_commands.h"
#include "ec_message.h"
/* Common utilities */
void *__weak crosec_get_buffer(size_t size, int req)
{
printk(BIOS_DEBUG, "crosec_get_buffer() implementation required.\n");
return NULL;
}
/* Dumps EC command / response data into debug output.
*
* @param name Message prefix name.
* @param cmd Command code, or -1 to ignore cmd message.
* @param data Data buffer to print.
* @param len Length of data.
*/
static void cros_ec_dump_data(const char *name, int cmd, const uint8_t *data,
int len)
{
int i;
printk(BIOS_DEBUG, "%s: ", name);
if (cmd != -1)
printk(BIOS_DEBUG, "cmd=%#x: ", cmd);
for (i = 0; i < len; i++)
printk(BIOS_DEBUG, "%02x ", data[i]);
printk(BIOS_DEBUG, "\n");
}
/* Calculate a simple 8-bit checksum of a data block
*
* @param data Data block to checksum
* @param size Size of data block in bytes
* @return checksum value (0 to 255)
*/
static int cros_ec_calc_checksum(const uint8_t *data, int size)
{
int csum, i;
for (i = csum = 0; i < size; i++)
csum += data[i];
return csum & 0xff;
}
/* Standard Chrome EC protocol, version 3 */
struct ec_command_v3 {
struct ec_host_request header;
uint8_t data[MSG_BYTES];
};
struct ec_response_v3 {
struct ec_host_response header;
uint8_t data[MSG_BYTES];
};
/**
* Create a request packet for protocol version 3.
*
* @param cec_command Command description.
* @param cmd Packed command bit stream.
* @return packet size in bytes, or <0 if error.
*/
static int create_proto3_request(const struct chromeec_command *cec_command,
struct ec_command_v3 *cmd)
{
struct ec_host_request *rq = &cmd->header;
int out_bytes = cec_command->cmd_size_in + sizeof(*rq);
/* Fail if output size is too big */
if (out_bytes > sizeof(*cmd)) {
printk(BIOS_ERR, "%s: Cannot send %d bytes\n", __func__,
cec_command->cmd_size_in);
return -EC_RES_REQUEST_TRUNCATED;
}
/* Fill in request packet */
rq->struct_version = EC_HOST_REQUEST_VERSION;
rq->checksum = 0;
rq->command = cec_command->cmd_code;
rq->command_version = cec_command->cmd_version;
rq->reserved = 0;
rq->data_len = cec_command->cmd_size_in;
/* Copy data after header */
memcpy(cmd->data, cec_command->cmd_data_in, cec_command->cmd_size_in);
/* Write checksum field so the entire packet sums to 0 */
rq->checksum = (uint8_t)(-cros_ec_calc_checksum(
(const uint8_t*)cmd, out_bytes));
cros_ec_dump_data("out", rq->command, (const uint8_t *)cmd, out_bytes);
/* Return size of request packet */
return out_bytes;
}
/**
* Prepare the device to receive a protocol version 3 response.
*
* @param cec_command Command description.
* @param resp Response buffer.
* @return maximum expected number of bytes in response, or <0 if error.
*/
static int prepare_proto3_response_buffer(
const struct chromeec_command *cec_command,
struct ec_response_v3 *resp)
{
int in_bytes = cec_command->cmd_size_out + sizeof(resp->header);
/* Fail if input size is too big */
if (in_bytes > sizeof(*resp)) {
printk(BIOS_ERR, "%s: Cannot receive %d bytes\n", __func__,
cec_command->cmd_size_out);
return -EC_RES_RESPONSE_TOO_BIG;
}
/* Return expected size of response packet */
return in_bytes;
}
/**
* Handle a protocol version 3 response packet.
*
* The packet must already be stored in the response buffer.
*
* @param resp Response buffer.
* @param cec_command Command structure to receive valid response.
* @return number of bytes of response data, or <0 if error
*/
static int handle_proto3_response(struct ec_response_v3 *resp,
struct chromeec_command *cec_command)
{
struct ec_host_response *rs = &resp->header;
int in_bytes;
int csum;
cros_ec_dump_data("in-header", -1, (const uint8_t*)rs, sizeof(*rs));
/* Check input data */
if (rs->struct_version != EC_HOST_RESPONSE_VERSION) {
printk(BIOS_ERR, "%s: EC response version mismatch\n", __func__);
return -EC_RES_INVALID_RESPONSE;
}
if (rs->reserved) {
printk(BIOS_ERR, "%s: EC response reserved != 0\n", __func__);
return -EC_RES_INVALID_RESPONSE;
}
if (rs->data_len > sizeof(resp->data) ||
rs->data_len > cec_command->cmd_size_out) {
printk(BIOS_ERR, "%s: EC returned too much data\n", __func__);
return -EC_RES_RESPONSE_TOO_BIG;
}
cros_ec_dump_data("in-data", -1, resp->data, rs->data_len);
/* Update in_bytes to actual data size */
in_bytes = sizeof(*rs) + rs->data_len;
/* Verify checksum */
csum = cros_ec_calc_checksum((const uint8_t *)resp, in_bytes);
if (csum) {
printk(BIOS_ERR, "%s: EC response checksum invalid: 0x%02x\n",
__func__, csum);
return -EC_RES_INVALID_CHECKSUM;
}
/* Return raw response. */
cec_command->cmd_code = rs->result;
cec_command->cmd_size_out = rs->data_len;
memcpy(cec_command->cmd_data_out, resp->data, rs->data_len);
/* Return error result, if any */
if (rs->result) {
printk(BIOS_ERR, "%s: EC response with error code: %d\n",
__func__, rs->result);
return -(int)rs->result;
}
return rs->data_len;
}
static int send_command_proto3(struct chromeec_command *cec_command,
crosec_io_t crosec_io, void *context)
{
int out_bytes, in_bytes;
int rv;
struct ec_command_v3 *cmd;
struct ec_response_v3 *resp;
if ((cmd = crosec_get_buffer(sizeof(*cmd), 1)) == NULL)
return -EC_RES_ERROR;
if ((resp = crosec_get_buffer(sizeof(*resp), 0)) == NULL)
return -EC_RES_ERROR;
/* Create request packet */
out_bytes = create_proto3_request(cec_command, cmd);
if (out_bytes < 0) {
return out_bytes;
}
/* Prepare response buffer */
in_bytes = prepare_proto3_response_buffer(cec_command, resp);
if (in_bytes < 0) {
return in_bytes;
}
rv = crosec_io(out_bytes, in_bytes, context);
if (rv != 0) {
printk(BIOS_ERR, "%s: failed to complete I/O: Err = %#x.\n",
__func__, rv >= 0 ? rv : -rv);
return -EC_RES_ERROR;
}
/* Process the response */
return handle_proto3_response(resp, cec_command);
}
static int crosec_command_proto_v3(struct chromeec_command *cec_command,
crosec_io_t crosec_io, void *context)
{
int rv = send_command_proto3(cec_command, crosec_io, context);
if (rv < 0) {
cec_command->cmd_code = rv;
return 1;
}
return 0;
}
int crosec_command_proto(struct chromeec_command *cec_command,
crosec_io_t crosec_io, void *context)
{
// TODO(hungte) Detect and fallback to v2 if we need.
return crosec_command_proto_v3(cec_command, crosec_io, context);
}
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