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* ChromeOS EC communication protocol helper functions
*
* Copyright (C) 2015 Google, Inc
*
* This software is licensed under the terms of the GNU General Public
* License version 2, as published by the Free Software Foundation, and
* may be copied, distributed, and modified under those terms.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
*/
#include <linux/mfd/cros_ec.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/module.h>
#include <linux/slab.h>
#define EC_COMMAND_RETRIES 50
static int prepare_packet(struct cros_ec_device *ec_dev,
struct cros_ec_command *msg)
{
struct ec_host_request *request;
u8 *out;
int i;
u8 csum = 0;
BUG_ON(ec_dev->proto_version != EC_HOST_REQUEST_VERSION);
BUG_ON(msg->outsize + sizeof(*request) > ec_dev->dout_size);
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 send_command(struct cros_ec_device *ec_dev,
struct cros_ec_command *msg)
{
int ret;
if (ec_dev->proto_version > 2)
ret = ec_dev->pkt_xfer(ec_dev, msg);
else
ret = ec_dev->cmd_xfer(ec_dev, msg);
if (msg->result == EC_RES_IN_PROGRESS) {
int i;
struct cros_ec_command *status_msg;
struct ec_response_get_comms_status *status;
status_msg = kmalloc(sizeof(*status_msg) + sizeof(*status),
GFP_KERNEL);
if (!status_msg)
return -ENOMEM;
status_msg->version = 0;
status_msg->command = EC_CMD_GET_COMMS_STATUS;
status_msg->insize = sizeof(*status);
status_msg->outsize = 0;
/*
* Query the EC's status until it's no longer busy or
* we encounter an error.
*/
for (i = 0; i < EC_COMMAND_RETRIES; i++) {
usleep_range(10000, 11000);
ret = ec_dev->cmd_xfer(ec_dev, status_msg);
if (ret < 0)
break;
msg->result = status_msg->result;
if (status_msg->result != EC_RES_SUCCESS)
break;
status = (struct ec_response_get_comms_status *)
status_msg->data;
if (!(status->flags & EC_COMMS_STATUS_PROCESSING))
break;
}
kfree(status_msg);
}
return ret;
}
int cros_ec_prepare_tx(struct cros_ec_device *ec_dev,
struct cros_ec_command *msg)
{
u8 *out;
u8 csum;
int i;
if (ec_dev->proto_version > 2)
return prepare_packet(ec_dev, msg);
BUG_ON(msg->outsize > EC_PROTO2_MAX_PARAM_SIZE);
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;
}
EXPORT_SYMBOL(cros_ec_prepare_tx);
int cros_ec_check_result(struct cros_ec_device *ec_dev,
struct cros_ec_command *msg)
{
switch (msg->result) {
case EC_RES_SUCCESS:
return 0;
case EC_RES_IN_PROGRESS:
dev_dbg(ec_dev->dev, "command 0x%02x in progress\n",
msg->command);
return -EAGAIN;
default:
dev_dbg(ec_dev->dev, "command 0x%02x returned %d\n",
msg->command, msg->result);
return 0;
}
}
EXPORT_SYMBOL(cros_ec_check_result);
static int cros_ec_host_command_proto_query(struct cros_ec_device *ec_dev,
int devidx,
struct cros_ec_command *msg)
{
/*
* Try using v3+ to query for supported protocols. If this
* command fails, fall back to v2. Returns the highest protocol
* supported by the EC.
* Also sets the max request/response/passthru size.
*/
int ret;
if (!ec_dev->pkt_xfer)
return -EPROTONOSUPPORT;
memset(msg, 0, sizeof(*msg));
msg->command = EC_CMD_PASSTHRU_OFFSET(devidx) | EC_CMD_GET_PROTOCOL_INFO;
msg->insize = sizeof(struct ec_response_get_protocol_info);
ret = send_command(ec_dev, msg);
if (ret < 0) {
dev_dbg(ec_dev->dev,
"failed to check for EC[%d] protocol version: %d\n",
devidx, ret);
return ret;
}
if (devidx > 0 && msg->result == EC_RES_INVALID_COMMAND)
return -ENODEV;
else if (msg->result != EC_RES_SUCCESS)
return msg->result;
return 0;
}
static int cros_ec_host_command_proto_query_v2(struct cros_ec_device *ec_dev)
{
struct cros_ec_command *msg;
struct ec_params_hello *hello_params;
struct ec_response_hello *hello_response;
int ret;
int len = max(sizeof(*hello_params), sizeof(*hello_response));
msg = kmalloc(sizeof(*msg) + len, GFP_KERNEL);
if (!msg)
return -ENOMEM;
msg->version = 0;
msg->command = EC_CMD_HELLO;
hello_params = (struct ec_params_hello *)msg->data;
msg->outsize = sizeof(*hello_params);
hello_response = (struct ec_response_hello *)msg->data;
msg->insize = sizeof(*hello_response);
hello_params->in_data = 0xa0b0c0d0;
ret = send_command(ec_dev, msg);
if (ret < 0) {
dev_dbg(ec_dev->dev,
"EC failed to respond to v2 hello: %d\n",
ret);
goto exit;
} else if (msg->result != EC_RES_SUCCESS) {
dev_err(ec_dev->dev,
"EC responded to v2 hello with error: %d\n",
msg->result);
ret = msg->result;
goto exit;
} else if (hello_response->out_data != 0xa1b2c3d4) {
dev_err(ec_dev->dev,
"EC responded to v2 hello with bad result: %u\n",
hello_response->out_data);
ret = -EBADMSG;
goto exit;
}
ret = 0;
exit:
kfree(msg);
return ret;
}
int cros_ec_query_all(struct cros_ec_device *ec_dev)
{
struct device *dev = ec_dev->dev;
struct cros_ec_command *proto_msg;
struct ec_response_get_protocol_info *proto_info;
int ret;
proto_msg = kzalloc(sizeof(*proto_msg) + sizeof(*proto_info),
GFP_KERNEL);
if (!proto_msg)
return -ENOMEM;
/* First try sending with proto v3. */
ec_dev->proto_version = 3;
ret = cros_ec_host_command_proto_query(ec_dev, 0, proto_msg);
if (ret == 0) {
proto_info = (struct ec_response_get_protocol_info *)
proto_msg->data;
ec_dev->max_request = proto_info->max_request_packet_size -
sizeof(struct ec_host_request);
ec_dev->max_response = proto_info->max_response_packet_size -
sizeof(struct ec_host_response);
ec_dev->proto_version =
min(EC_HOST_REQUEST_VERSION,
fls(proto_info->protocol_versions) - 1);
dev_dbg(ec_dev->dev,
"using proto v%u\n",
ec_dev->proto_version);
ec_dev->din_size = ec_dev->max_response +
sizeof(struct ec_host_response) +
EC_MAX_RESPONSE_OVERHEAD;
ec_dev->dout_size = ec_dev->max_request +
sizeof(struct ec_host_request) +
EC_MAX_REQUEST_OVERHEAD;
/*
* Check for PD
*/
ret = cros_ec_host_command_proto_query(ec_dev, 1, proto_msg);
if (ret) {
dev_dbg(ec_dev->dev, "no PD chip found: %d\n", ret);
ec_dev->max_passthru = 0;
} else {
dev_dbg(ec_dev->dev, "found PD chip\n");
ec_dev->max_passthru =
proto_info->max_request_packet_size -
sizeof(struct ec_host_request);
}
} else {
/* Try querying with a v2 hello message. */
ec_dev->proto_version = 2;
ret = cros_ec_host_command_proto_query_v2(ec_dev);
if (ret == 0) {
/* V2 hello succeeded. */
dev_dbg(ec_dev->dev, "falling back to proto v2\n");
ec_dev->max_request = EC_PROTO2_MAX_PARAM_SIZE;
ec_dev->max_response = EC_PROTO2_MAX_PARAM_SIZE;
ec_dev->max_passthru = 0;
ec_dev->pkt_xfer = NULL;
ec_dev->din_size = EC_MSG_BYTES;
ec_dev->dout_size = EC_MSG_BYTES;
} else {
/*
* It's possible for a test to occur too early when
* the EC isn't listening. If this happens, we'll
* test later when the first command is run.
*/
ec_dev->proto_version = EC_PROTO_VERSION_UNKNOWN;
dev_dbg(ec_dev->dev, "EC query failed: %d\n", ret);
goto exit;
}
}
devm_kfree(dev, ec_dev->din);
devm_kfree(dev, ec_dev->dout);
ec_dev->din = devm_kzalloc(dev, ec_dev->din_size, GFP_KERNEL);
if (!ec_dev->din) {
ret = -ENOMEM;
goto exit;
}
ec_dev->dout = devm_kzalloc(dev, ec_dev->dout_size, GFP_KERNEL);
if (!ec_dev->dout) {
devm_kfree(dev, ec_dev->din);
ret = -ENOMEM;
goto exit;
}
exit:
kfree(proto_msg);
return ret;
}
EXPORT_SYMBOL(cros_ec_query_all);
int cros_ec_cmd_xfer(struct cros_ec_device *ec_dev,
struct cros_ec_command *msg)
{
int ret;
mutex_lock(&ec_dev->lock);
if (ec_dev->proto_version == EC_PROTO_VERSION_UNKNOWN) {
ret = cros_ec_query_all(ec_dev);
if (ret) {
dev_err(ec_dev->dev,
"EC version unknown and query failed; aborting command\n");
mutex_unlock(&ec_dev->lock);
return ret;
}
}
if (msg->insize > ec_dev->max_response) {
dev_dbg(ec_dev->dev, "clamping message receive buffer\n");
msg->insize = ec_dev->max_response;
}
if (msg->command < EC_CMD_PASSTHRU_OFFSET(1)) {
if (msg->outsize > ec_dev->max_request) {
dev_err(ec_dev->dev,
"request of size %u is too big (max: %u)\n",
msg->outsize,
ec_dev->max_request);
mutex_unlock(&ec_dev->lock);
return -EMSGSIZE;
}
} else {
if (msg->outsize > ec_dev->max_passthru) {
dev_err(ec_dev->dev,
"passthru rq of size %u is too big (max: %u)\n",
msg->outsize,
ec_dev->max_passthru);
mutex_unlock(&ec_dev->lock);
return -EMSGSIZE;
}
}
ret = send_command(ec_dev, msg);
mutex_unlock(&ec_dev->lock);
return ret;
}
EXPORT_SYMBOL(cros_ec_cmd_xfer);
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