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/module.h>
#include <linux/platform_data/cros_ec_commands.h>
#include <linux/platform_data/cros_ec_proto.h>
#include <linux/slab.h>
#include <asm/unaligned.h>

#include "cros_ec_trace.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;
	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, ret);
	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);

			trace_cros_ec_request_start(status_msg);
			ret = (*xfer_fxn)(ec_dev, status_msg);
			trace_cros_ec_request_done(status_msg, ret);
			if (ret == -EAGAIN)
				continue;
			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;
}

/**
 * cros_ec_prepare_tx() - Prepare an outgoing message in the output buffer.
 * @ec_dev: Device to register.
 * @msg: Message to write.
 *
 * This is intended to be used by all ChromeOS EC drivers, but at present
 * only SPI uses it. Once LPC uses the same protocol it can start using it.
 * I2C could use it now, with a refactor of the existing code.
 *
 * Return: 0 on success or negative error code.
 */
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);

/**
 * cros_ec_check_result() - Check ec_msg->result.
 * @ec_dev: EC device.
 * @msg: Message to check.
 *
 * This is used by ChromeOS EC drivers to check the ec_msg->result for
 * errors and to warn about them.
 *
 * Return: 0 on success or negative error code.
 */
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);

/*
 * cros_ec_get_host_event_wake_mask
 *
 * Get the mask of host events that cause wake from suspend.
 *
 * @ec_dev: EC device to call
 * @msg: message structure to use
 * @mask: result when function returns >=0.
 *
 * LOCKING:
 * the caller has ec_dev->lock mutex, or the caller knows there is
 * no other command in progress.
 */
static int cros_ec_get_host_event_wake_mask(struct cros_ec_device *ec_dev,
					    struct cros_ec_command *msg,
					    uint32_t *mask)
{
	struct ec_response_host_event_mask *r;
	int ret;

	msg->command = EC_CMD_HOST_EVENT_GET_WAKE_MASK;
	msg->version = 0;
	msg->outsize = 0;
	msg->insize = sizeof(*r);

	ret = send_command(ec_dev, msg);
	if (ret > 0) {
		r = (struct ec_response_host_event_mask *)msg->data;
		*mask = r->mask;
	}

	return ret;
}

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;
}

/*
 * cros_ec_get_host_command_version_mask
 *
 * Get the version mask of a given command.
 *
 * @ec_dev: EC device to call
 * @msg: message structure to use
 * @cmd: command to get the version of.
 * @mask: result when function returns 0.
 *
 * @return 0 on success, error code otherwise
 *
 * LOCKING:
 * the caller has ec_dev->lock mutex or the caller knows there is
 * no other command in progress.
 */
static int cros_ec_get_host_command_version_mask(struct cros_ec_device *ec_dev,
	u16 cmd, u32 *mask)
{
	struct ec_params_get_cmd_versions *pver;
	struct ec_response_get_cmd_versions *rver;
	struct cros_ec_command *msg;
	int ret;

	msg = kmalloc(sizeof(*msg) + max(sizeof(*rver), sizeof(*pver)),
		      GFP_KERNEL);
	if (!msg)
		return -ENOMEM;

	msg->version = 0;
	msg->command = EC_CMD_GET_CMD_VERSIONS;
	msg->insize = sizeof(*rver);
	msg->outsize = sizeof(*pver);

	pver = (struct ec_params_get_cmd_versions *)msg->data;
	pver->cmd = cmd;

	ret = send_command(ec_dev, msg);
	if (ret > 0) {
		rver = (struct ec_response_get_cmd_versions *)msg->data;
		*mask = rver->version_mask;
	}

	kfree(msg);

	return ret;
}

/**
 * cros_ec_query_all() -  Query the protocol version supported by the
 *         ChromeOS EC.
 * @ec_dev: Device to register.
 *
 * Return: 0 on success or negative error code.
 */
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;
	u32 ver_mask = 0;
	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_PROTO2_MSG_BYTES;
			ec_dev->dout_size = EC_PROTO2_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;
	}

	/* Probe if MKBP event is supported */
	ret = cros_ec_get_host_command_version_mask(ec_dev,
						    EC_CMD_GET_NEXT_EVENT,
						    &ver_mask);
	if (ret < 0 || ver_mask == 0)
		ec_dev->mkbp_event_supported = 0;
	else
		ec_dev->mkbp_event_supported = fls(ver_mask);

	dev_dbg(ec_dev->dev, "MKBP support version %u\n",
		ec_dev->mkbp_event_supported - 1);

	/* Probe if host sleep v1 is supported for S0ix failure detection. */
	ret = cros_ec_get_host_command_version_mask(ec_dev,
						    EC_CMD_HOST_SLEEP_EVENT,
						    &ver_mask);
	ec_dev->host_sleep_v1 = (ret >= 0 && (ver_mask & EC_VER_MASK(1)));

	/*
	 * Get host event wake mask, assume all events are wake events
	 * if unavailable.
	 */
	ret = cros_ec_get_host_event_wake_mask(ec_dev, proto_msg,
					       &ec_dev->host_event_wake_mask);
	if (ret < 0)
		ec_dev->host_event_wake_mask = U32_MAX;

	ret = 0;

exit:
	kfree(proto_msg);
	return ret;
}
EXPORT_SYMBOL(cros_ec_query_all);

/**
 * cros_ec_cmd_xfer() - Send a command to the ChromeOS EC.
 * @ec_dev: EC device.
 * @msg: Message to write.
 *
 * Call this to send a command to the ChromeOS EC.  This should be used
 * instead of calling the EC's cmd_xfer() callback directly.
 *
 * Return: 0 on success or negative error code.
 */
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);

/**
 * cros_ec_cmd_xfer_status() - Send a command to the ChromeOS EC.
 * @ec_dev: EC device.
 * @msg: Message to write.
 *
 * This function is identical to cros_ec_cmd_xfer, except it returns success
 * status only if both the command was transmitted successfully and the EC
 * replied with success status. It's not necessary to check msg->result when
 * using this function.
 *
 * Return:
 * >=0 - The number of bytes transferred
 * -ENOTSUPP - Operation not supported
 * -EPROTO - Protocol error
 */
int cros_ec_cmd_xfer_status(struct cros_ec_device *ec_dev,
			    struct cros_ec_command *msg)
{
	int ret;

	ret = cros_ec_cmd_xfer(ec_dev, msg);
	if (ret < 0) {
		dev_err(ec_dev->dev, "Command xfer error (err:%d)\n", ret);
	} else if (msg->result == EC_RES_INVALID_VERSION) {
		dev_dbg(ec_dev->dev, "Command invalid version (err:%d)\n",
			msg->result);
		return -ENOTSUPP;
	} else if (msg->result != EC_RES_SUCCESS) {
		dev_dbg(ec_dev->dev, "Command result (err: %d)\n", msg->result);
		return -EPROTO;
	}

	return ret;
}
EXPORT_SYMBOL(cros_ec_cmd_xfer_status);

static int get_next_event_xfer(struct cros_ec_device *ec_dev,
			       struct cros_ec_command *msg,
			       struct ec_response_get_next_event_v1 *event,
			       int version, uint32_t size)
{
	int ret;

	msg->version = version;
	msg->command = EC_CMD_GET_NEXT_EVENT;
	msg->insize = size;
	msg->outsize = 0;

	ret = cros_ec_cmd_xfer(ec_dev, msg);
	if (ret > 0) {
		ec_dev->event_size = ret - 1;
		ec_dev->event_data = *event;
	}

	return ret;
}

static int get_next_event(struct cros_ec_device *ec_dev)
{
	struct {
		struct cros_ec_command msg;
		struct ec_response_get_next_event_v1 event;
	} __packed buf;
	struct cros_ec_command *msg = &buf.msg;
	struct ec_response_get_next_event_v1 *event = &buf.event;
	const int cmd_version = ec_dev->mkbp_event_supported - 1;

	memset(msg, 0, sizeof(*msg));
	if (ec_dev->suspended) {
		dev_dbg(ec_dev->dev, "Device suspended.\n");
		return -EHOSTDOWN;
	}

	if (cmd_version == 0)
		return get_next_event_xfer(ec_dev, msg, event, 0,
				  sizeof(struct ec_response_get_next_event));

	return get_next_event_xfer(ec_dev, msg, event, cmd_version,
				sizeof(struct ec_response_get_next_event_v1));
}

static int get_keyboard_state_event(struct cros_ec_device *ec_dev)
{
	u8 buffer[sizeof(struct cros_ec_command) +
		  sizeof(ec_dev->event_data.data)];
	struct cros_ec_command *msg = (struct cros_ec_command *)&buffer;

	msg->version = 0;
	msg->command = EC_CMD_MKBP_STATE;
	msg->insize = sizeof(ec_dev->event_data.data);
	msg->outsize = 0;

	ec_dev->event_size = cros_ec_cmd_xfer(ec_dev, msg);
	ec_dev->event_data.event_type = EC_MKBP_EVENT_KEY_MATRIX;
	memcpy(&ec_dev->event_data.data, msg->data,
	       sizeof(ec_dev->event_data.data));

	return ec_dev->event_size;
}

/**
 * cros_ec_get_next_event() - Fetch next event from the ChromeOS EC.
 * @ec_dev: Device to fetch event from.
 * @wake_event: Pointer to a bool set to true upon return if the event might be
 *              treated as a wake event. Ignored if null.
 * @has_more_events: Pointer to bool set to true if more than one event is
 *              pending.
 *              Some EC will set this flag to indicate cros_ec_get_next_event()
 *              can be called multiple times in a row.
 *              It is an optimization to prevent issuing a EC command for
 *              nothing or wait for another interrupt from the EC to process
 *              the next message.
 *              Ignored if null.
 *
 * Return: negative error code on errors; 0 for no data; or else number of
 * bytes received (i.e., an event was retrieved successfully). Event types are
 * written out to @ec_dev->event_data.event_type on success.
 */
int cros_ec_get_next_event(struct cros_ec_device *ec_dev,
			   bool *wake_event,
			   bool *has_more_events)
{
	u8 event_type;
	u32 host_event;
	int ret;

	/*
	 * Default value for wake_event.
	 * Wake up on keyboard event, wake up for spurious interrupt or link
	 * error to the EC.
	 */
	if (wake_event)
		*wake_event = true;

	/*
	 * Default value for has_more_events.
	 * EC will raise another interrupt if AP does not process all events
	 * anyway.
	 */
	if (has_more_events)
		*has_more_events = false;

	if (!ec_dev->mkbp_event_supported)
		return get_keyboard_state_event(ec_dev);

	ret = get_next_event(ec_dev);
	if (ret <= 0)
		return ret;

	if (has_more_events)
		*has_more_events = ec_dev->event_data.event_type &
			EC_MKBP_HAS_MORE_EVENTS;
	ec_dev->event_data.event_type &= EC_MKBP_EVENT_TYPE_MASK;

	if (wake_event) {
		event_type = ec_dev->event_data.event_type;
		host_event = cros_ec_get_host_event(ec_dev);

		/*
		 * Sensor events need to be parsed by the sensor sub-device.
		 * Defer them, and don't report the wakeup here.
		 */
		if (event_type == EC_MKBP_EVENT_SENSOR_FIFO)
			*wake_event = false;
		/* Masked host-events should not count as wake events. */
		else if (host_event &&
			 !(host_event & ec_dev->host_event_wake_mask))
			*wake_event = false;
	}

	return ret;
}
EXPORT_SYMBOL(cros_ec_get_next_event);

/**
 * cros_ec_get_host_event() - Return a mask of event set by the ChromeOS EC.
 * @ec_dev: Device to fetch event from.
 *
 * When MKBP is supported, when the EC raises an interrupt, we collect the
 * events raised and call the functions in the ec notifier. This function
 * is a helper to know which events are raised.
 *
 * Return: 0 on error or non-zero bitmask of one or more EC_HOST_EVENT_*.
 */
u32 cros_ec_get_host_event(struct cros_ec_device *ec_dev)
{
	u32 host_event;

	BUG_ON(!ec_dev->mkbp_event_supported);

	if (ec_dev->event_data.event_type != EC_MKBP_EVENT_HOST_EVENT)
		return 0;

	if (ec_dev->event_size != sizeof(host_event)) {
		dev_warn(ec_dev->dev, "Invalid host event size\n");
		return 0;
	}

	host_event = get_unaligned_le32(&ec_dev->event_data.data.host_event);

	return host_event;
}
EXPORT_SYMBOL(cros_ec_get_host_event);

/**
 * cros_ec_check_features() - Test for the presence of EC features
 *
 * @ec: EC device, does not have to be connected directly to the AP,
 *      can be daisy chained through another device.
 * @feature: One of ec_feature_code bit.
 *
 * Call this function to test whether the ChromeOS EC supports a feature.
 *
 * Return: 1 if supported, 0 if not
 */
int cros_ec_check_features(struct cros_ec_dev *ec, int feature)
{
	struct cros_ec_command *msg;
	int ret;

	if (ec->features[0] == -1U && ec->features[1] == -1U) {
		/* features bitmap not read yet */
		msg = kzalloc(sizeof(*msg) + sizeof(ec->features), GFP_KERNEL);
		if (!msg)
			return -ENOMEM;

		msg->command = EC_CMD_GET_FEATURES + ec->cmd_offset;
		msg->insize = sizeof(ec->features);

		ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
		if (ret < 0) {
			dev_warn(ec->dev, "cannot get EC features: %d/%d\n",
				 ret, msg->result);
			memset(ec->features, 0, sizeof(ec->features));
		} else {
			memcpy(ec->features, msg->data, sizeof(ec->features));
		}

		dev_dbg(ec->dev, "EC features %08x %08x\n",
			ec->features[0], ec->features[1]);

		kfree(msg);
	}

	return ec->features[feature / 32] & EC_FEATURE_MASK_0(feature);
}
EXPORT_SYMBOL_GPL(cros_ec_check_features);

/**
 * cros_ec_get_sensor_count() - Return the number of MEMS sensors supported.
 *
 * @ec: EC device, does not have to be connected directly to the AP,
 *      can be daisy chained through another device.
 * Return: < 0 in case of error.
 */
int cros_ec_get_sensor_count(struct cros_ec_dev *ec)
{
	/*
	 * Issue a command to get the number of sensor reported.
	 * If not supported, check for legacy mode.
	 */
	int ret, sensor_count;
	struct ec_params_motion_sense *params;
	struct ec_response_motion_sense *resp;
	struct cros_ec_command *msg;
	struct cros_ec_device *ec_dev = ec->ec_dev;
	u8 status;

	msg = kzalloc(sizeof(*msg) + max(sizeof(*params), sizeof(*resp)),
		      GFP_KERNEL);
	if (!msg)
		return -ENOMEM;

	msg->version = 1;
	msg->command = EC_CMD_MOTION_SENSE_CMD + ec->cmd_offset;
	msg->outsize = sizeof(*params);
	msg->insize = sizeof(*resp);

	params = (struct ec_params_motion_sense *)msg->data;
	params->cmd = MOTIONSENSE_CMD_DUMP;

	ret = cros_ec_cmd_xfer(ec->ec_dev, msg);
	if (ret < 0) {
		sensor_count = ret;
	} else if (msg->result != EC_RES_SUCCESS) {
		sensor_count = -EPROTO;
	} else {
		resp = (struct ec_response_motion_sense *)msg->data;
		sensor_count = resp->dump.sensor_count;
	}
	kfree(msg);

	/*
	 * Check legacy mode: Let's find out if sensors are accessible
	 * via LPC interface.
	 */
	if (sensor_count == -EPROTO &&
	    ec->cmd_offset == 0 &&
	    ec_dev->cmd_readmem) {
		ret = ec_dev->cmd_readmem(ec_dev, EC_MEMMAP_ACC_STATUS,
				1, &status);
		if (ret >= 0 &&
		    (status & EC_MEMMAP_ACC_STATUS_PRESENCE_BIT)) {
			/*
			 * We have 2 sensors, one in the lid, one in the base.
			 */
			sensor_count = 2;
		} else {
			/*
			 * EC uses LPC interface and no sensors are presented.
			 */
			sensor_count = 0;
		}
	} else if (sensor_count == -EPROTO) {
		/* EC responded, but does not understand DUMP command. */
		sensor_count = 0;
	}
	return sensor_count;
}
EXPORT_SYMBOL_GPL(cros_ec_get_sensor_count);