--- /dev/null
+/*
+ * 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);
Code Review / kvmfornfv.git / blobdiff