1 files changed, 382 insertions, 0 deletions
diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/platform/chrome/cros_ec_proto.c
new file mode 100644
index 000000000000..990308ca384f
--- /dev/null
+++ b/drivers/platform/chrome/cros_ec_proto.c
@@ -0,0 +1,382 @@
+/*
+ * 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);