drivers/i2c/busses/i2c-cros-ec-tunnel.c - kernel/bruno - Git at Google

 /*
  *  Copyright (C) 2013 Google, Inc
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
  *  the Free Software Foundation; either version 2 of the License, or
  *  (at your option) any later version.
  *
  * Expose an I2C passthrough to the ChromeOS EC.
  */

 #include <linux/module.h>
 #include <linux/i2c.h>
 #include <linux/mfd/cros_ec.h>
 #include <linux/mfd/cros_ec_commands.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>

 #define I2C_MAX_RETRIES 3

 /**
  * struct ec_i2c_device - Driver data for I2C tunnel
  *
  * @dev: Device node
  * @adap: I2C adapter
  * @ec: Pointer to EC device
  * @remote_bus: The EC bus number we tunnel to on the other side.
  * @request_buf: Buffer for transmitting data; we expect most transfers to fit.
  * @response_buf: Buffer for receiving data; we expect most transfers to fit.
  */

 struct ec_i2c_device {
 	struct device *dev;
 	struct i2c_adapter adap;
 	struct cros_ec_device *ec;

 	u16 remote_bus;

 	u8 request_buf[256];
 	u8 response_buf[256];
 };

 /**
  * ec_i2c_count_message - Count bytes needed for ec_i2c_construct_message
  *
  * @i2c_msgs: The i2c messages to read
  * @num: The number of i2c messages.
  *
  * Returns the number of bytes the messages will take up.
  */
 static int ec_i2c_count_message(const struct i2c_msg i2c_msgs[], int num)
 {
 	int i;
 	int size;

 	size = sizeof(struct ec_params_i2c_passthru);
 	size += num * sizeof(struct ec_params_i2c_passthru_msg);
 	for (i = 0; i < num; i++)
 		if (!(i2c_msgs[i].flags & I2C_M_RD))
 			size += i2c_msgs[i].len;

 	return size;
 }

 /**
  * ec_i2c_construct_message - construct a message to go to the EC
  *
  * This function effectively stuffs the standard i2c_msg format of Linux into
  * a format that the EC understands.
  *
  * @buf: The buffer to fill.  We assume that the buffer is big enough.
  * @i2c_msgs: The i2c messages to read.
  * @num: The number of i2c messages.
  * @bus_num: The remote bus number we want to talk to.
  *
  * Returns 0 or a negative error number.
  */
 static int ec_i2c_construct_message(u8 *buf, const struct i2c_msg i2c_msgs[],
 				    int num, u16 bus_num)
 {
 	struct ec_params_i2c_passthru *params;
 	u8 *out_data;
 	int i;

 	out_data = buf + sizeof(struct ec_params_i2c_passthru) +
 		   num * sizeof(struct ec_params_i2c_passthru_msg);

 	params = (struct ec_params_i2c_passthru *)buf;
 	params->port = bus_num;
 	params->num_msgs = num;
 	for (i = 0; i < num; i++) {
 		const struct i2c_msg *i2c_msg = &i2c_msgs[i];
 		struct ec_params_i2c_passthru_msg *msg = &params->msg[i];

 		msg->len = i2c_msg->len;
 		msg->addr_flags = i2c_msg->addr;

 		if (i2c_msg->flags & I2C_M_TEN)
 			return -EINVAL;

 		if (i2c_msg->flags & I2C_M_RD) {
 			msg->addr_flags |= EC_I2C_FLAG_READ;
 		} else {
 			memcpy(out_data, i2c_msg->buf, msg->len);
 			out_data += msg->len;
 		}
 	}

 	return 0;
 }

 /**
  * ec_i2c_count_response - Count bytes needed for ec_i2c_parse_response
  *
  * @i2c_msgs: The i2c messages to to fill up.
  * @num: The number of i2c messages expected.
  *
  * Returns the number of response bytes expeced.
  */
 static int ec_i2c_count_response(struct i2c_msg i2c_msgs[], int num)
 {
 	int size;
 	int i;

 	size = sizeof(struct ec_response_i2c_passthru);
 	for (i = 0; i < num; i++)
 		if (i2c_msgs[i].flags & I2C_M_RD)
 			size += i2c_msgs[i].len;

 	return size;
 }

 /**
  * ec_i2c_parse_response - Parse a response from the EC
  *
  * We'll take the EC's response and copy it back into msgs.
  *
  * @buf: The buffer to parse.
  * @i2c_msgs: The i2c messages to to fill up.
  * @num: The number of i2c messages; will be modified to include the actual
  *	 number received.
  *
  * Returns 0 or a negative error number.
  */
 static int ec_i2c_parse_response(const u8 *buf, struct i2c_msg i2c_msgs[],
 				 int *num)
 {
 	const struct ec_response_i2c_passthru *resp;
 	const u8 *in_data;
 	int i;

 	in_data = buf + sizeof(struct ec_response_i2c_passthru);

 	resp = (const struct ec_response_i2c_passthru *)buf;
 	if (resp->i2c_status & EC_I2C_STATUS_TIMEOUT)
 		return -ETIMEDOUT;
 	else if (resp->i2c_status & EC_I2C_STATUS_ERROR)
 		return -EREMOTEIO;

 	/* Other side could send us back fewer messages, but not more */
 	if (resp->num_msgs > *num)
 		return -EPROTO;
 	*num = resp->num_msgs;

 	for (i = 0; i < *num; i++) {
 		struct i2c_msg *i2c_msg = &i2c_msgs[i];

 		if (i2c_msgs[i].flags & I2C_M_RD) {
 			memcpy(i2c_msg->buf, in_data, i2c_msg->len);
 			in_data += i2c_msg->len;
 		}
 	}

 	return 0;
 }

 static int ec_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg i2c_msgs[],
 		       int num)
 {
 	struct ec_i2c_device *bus = adap->algo_data;
 	struct device *dev = bus->dev;
 	const u16 bus_num = bus->remote_bus;
 	int request_len;
 	int response_len;
 	int alloc_size;
 	int result;
 	struct cros_ec_command *msg;

 	request_len = ec_i2c_count_message(i2c_msgs, num);
 	if (request_len < 0) {
 		dev_warn(dev, "Error constructing message %d\n", request_len);
 		return request_len;
 	}

 	response_len = ec_i2c_count_response(i2c_msgs, num);
 	if (response_len < 0) {
 		/* Unexpected; no errors should come when NULL response */
 		dev_warn(dev, "Error preparing response %d\n", response_len);
 		return response_len;
 	}

 	alloc_size = max(request_len, response_len);
 	msg = kmalloc(sizeof(*msg) + alloc_size, GFP_KERNEL);
 	if (!msg)
 		return -ENOMEM;

 	result = ec_i2c_construct_message(msg->data, i2c_msgs, num, bus_num);
 	if (result) {
 		dev_err(dev, "Error constructing EC i2c message %d\n", result);
 		goto exit;
 	}

 	msg->version = 0;
 	msg->command = EC_CMD_I2C_PASSTHRU;
 	msg->outsize = request_len;
 	msg->insize = response_len;

 	result = cros_ec_cmd_xfer_status(bus->ec, msg);
 	if (result < 0) {
 		dev_err(dev, "Error transferring EC i2c message %d\n", result);
 		goto exit;
 	}

 	result = ec_i2c_parse_response(msg->data, i2c_msgs, &num);
 	if (result < 0) {
 		dev_err(dev, "Error parsing EC i2c message %d\n", result);
 		goto exit;
 	}

 	/* Indicate success by saying how many messages were sent */
 	result = num;
 exit:
 	kfree(msg);
 	return result;
 }

 static u32 ec_i2c_functionality(struct i2c_adapter *adap)
 {
 	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 }

 static const struct i2c_algorithm ec_i2c_algorithm = {
 	.master_xfer	= ec_i2c_xfer,
 	.functionality	= ec_i2c_functionality,
 };

 static int ec_i2c_probe(struct platform_device *pdev)
 {
 	struct device_node *np = pdev->dev.of_node;
 	struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent);
 	struct device *dev = &pdev->dev;
 	struct ec_i2c_device *bus = NULL;
 	u32 remote_bus;
 	int err;

 	if (!ec->cmd_xfer) {
 		dev_err(dev, "Missing sendrecv\n");
 		return -EINVAL;
 	}

 	bus = devm_kzalloc(dev, sizeof(*bus), GFP_KERNEL);
 	if (bus == NULL)
 		return -ENOMEM;

 	err = of_property_read_u32(np, "google,remote-bus", &remote_bus);
 	if (err) {
 		dev_err(dev, "Couldn't read remote-bus property\n");
 		return err;
 	}
 	bus->remote_bus = remote_bus;

 	bus->ec = ec;
 	bus->dev = dev;

 	bus->adap.owner = THIS_MODULE;
 	strlcpy(bus->adap.name, "cros-ec-i2c-tunnel", sizeof(bus->adap.name));
 	bus->adap.algo = &ec_i2c_algorithm;
 	bus->adap.algo_data = bus;
 	bus->adap.dev.parent = &pdev->dev;
 	bus->adap.dev.of_node = np;
 	bus->adap.retries = I2C_MAX_RETRIES;

 	err = i2c_add_adapter(&bus->adap);
 	if (err) {
 		dev_err(dev, "cannot register i2c adapter\n");
 		return err;
 	}
 	platform_set_drvdata(pdev, bus);

 	return err;
 }

 static int ec_i2c_remove(struct platform_device *dev)
 {
 	struct ec_i2c_device *bus = platform_get_drvdata(dev);

 	i2c_del_adapter(&bus->adap);

 	return 0;
 }

 #ifdef CONFIG_OF
 static const struct of_device_id cros_ec_i2c_of_match[] = {
 	{ .compatible = "google,cros-ec-i2c-tunnel" },
 	{},
 };
 MODULE_DEVICE_TABLE(of, cros_ec_i2c_of_match);
 #endif

 static struct platform_driver ec_i2c_tunnel_driver = {
 	.probe = ec_i2c_probe,
 	.remove = ec_i2c_remove,
 	.driver = {
 		.name = "cros-ec-i2c-tunnel",
 		.of_match_table = of_match_ptr(cros_ec_i2c_of_match),
 	},
 };

 module_platform_driver(ec_i2c_tunnel_driver);

 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("EC I2C tunnel driver");
 MODULE_ALIAS("platform:cros-ec-i2c-tunnel");
	/*
	* Copyright (C) 2013 Google, Inc
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*
	* Expose an I2C passthrough to the ChromeOS EC.
	*/

	#include <linux/module.h>
	#include <linux/i2c.h>
	#include <linux/mfd/cros_ec.h>
	#include <linux/mfd/cros_ec_commands.h>
	#include <linux/platform_device.h>
	#include <linux/slab.h>

	#define I2C_MAX_RETRIES 3

	/**
	* struct ec_i2c_device - Driver data for I2C tunnel
	*
	* @dev: Device node
	* @adap: I2C adapter
	* @ec: Pointer to EC device
	* @remote_bus: The EC bus number we tunnel to on the other side.
	* @request_buf: Buffer for transmitting data; we expect most transfers to fit.
	* @response_buf: Buffer for receiving data; we expect most transfers to fit.
	*/

	struct ec_i2c_device {
	struct device *dev;
	struct i2c_adapter adap;
	struct cros_ec_device *ec;

	u16 remote_bus;

	u8 request_buf[256];
	u8 response_buf[256];
	};

	/**
	* ec_i2c_count_message - Count bytes needed for ec_i2c_construct_message
	*
	* @i2c_msgs: The i2c messages to read
	* @num: The number of i2c messages.
	*
	* Returns the number of bytes the messages will take up.
	*/
	static int ec_i2c_count_message(const struct i2c_msg i2c_msgs[], int num)
	{
	int i;
	int size;

	size = sizeof(struct ec_params_i2c_passthru);
	size += num * sizeof(struct ec_params_i2c_passthru_msg);
	for (i = 0; i < num; i++)
	if (!(i2c_msgs[i].flags & I2C_M_RD))
	size += i2c_msgs[i].len;

	return size;
	}

	/**
	* ec_i2c_construct_message - construct a message to go to the EC
	*
	* This function effectively stuffs the standard i2c_msg format of Linux into
	* a format that the EC understands.
	*
	* @buf: The buffer to fill. We assume that the buffer is big enough.
	* @i2c_msgs: The i2c messages to read.
	* @num: The number of i2c messages.
	* @bus_num: The remote bus number we want to talk to.
	*
	* Returns 0 or a negative error number.
	*/
	static int ec_i2c_construct_message(u8 *buf, const struct i2c_msg i2c_msgs[],
	int num, u16 bus_num)
	{
	struct ec_params_i2c_passthru *params;
	u8 *out_data;
	int i;

	out_data = buf + sizeof(struct ec_params_i2c_passthru) +
	num * sizeof(struct ec_params_i2c_passthru_msg);

	params = (struct ec_params_i2c_passthru *)buf;
	params->port = bus_num;
	params->num_msgs = num;
	for (i = 0; i < num; i++) {
	const struct i2c_msg *i2c_msg = &i2c_msgs[i];
	struct ec_params_i2c_passthru_msg *msg = &params->msg[i];

	msg->len = i2c_msg->len;
	msg->addr_flags = i2c_msg->addr;

	if (i2c_msg->flags & I2C_M_TEN)
	return -EINVAL;

	if (i2c_msg->flags & I2C_M_RD) {
	msg->addr_flags \|= EC_I2C_FLAG_READ;
	} else {
	memcpy(out_data, i2c_msg->buf, msg->len);
	out_data += msg->len;
	}
	}

	return 0;
	}

	/**
	* ec_i2c_count_response - Count bytes needed for ec_i2c_parse_response
	*
	* @i2c_msgs: The i2c messages to to fill up.
	* @num: The number of i2c messages expected.
	*
	* Returns the number of response bytes expeced.
	*/
	static int ec_i2c_count_response(struct i2c_msg i2c_msgs[], int num)
	{
	int size;
	int i;

	size = sizeof(struct ec_response_i2c_passthru);
	for (i = 0; i < num; i++)
	if (i2c_msgs[i].flags & I2C_M_RD)
	size += i2c_msgs[i].len;

	return size;
	}

	/**
	* ec_i2c_parse_response - Parse a response from the EC
	*
	* We'll take the EC's response and copy it back into msgs.
	*
	* @buf: The buffer to parse.
	* @i2c_msgs: The i2c messages to to fill up.
	* @num: The number of i2c messages; will be modified to include the actual
	* number received.
	*
	* Returns 0 or a negative error number.
	*/
	static int ec_i2c_parse_response(const u8 *buf, struct i2c_msg i2c_msgs[],
	int *num)
	{
	const struct ec_response_i2c_passthru *resp;
	const u8 *in_data;
	int i;

	in_data = buf + sizeof(struct ec_response_i2c_passthru);

	resp = (const struct ec_response_i2c_passthru *)buf;
	if (resp->i2c_status & EC_I2C_STATUS_TIMEOUT)
	return -ETIMEDOUT;
	else if (resp->i2c_status & EC_I2C_STATUS_ERROR)
	return -EREMOTEIO;

	/* Other side could send us back fewer messages, but not more */
	if (resp->num_msgs > *num)
	return -EPROTO;
	*num = resp->num_msgs;

	for (i = 0; i < *num; i++) {
	struct i2c_msg *i2c_msg = &i2c_msgs[i];

	if (i2c_msgs[i].flags & I2C_M_RD) {
	memcpy(i2c_msg->buf, in_data, i2c_msg->len);
	in_data += i2c_msg->len;
	}
	}

	return 0;
	}

	static int ec_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg i2c_msgs[],
	int num)
	{
	struct ec_i2c_device *bus = adap->algo_data;
	struct device *dev = bus->dev;
	const u16 bus_num = bus->remote_bus;
	int request_len;
	int response_len;
	int alloc_size;
	int result;
	struct cros_ec_command *msg;

	request_len = ec_i2c_count_message(i2c_msgs, num);
	if (request_len < 0) {
	dev_warn(dev, "Error constructing message %d\n", request_len);
	return request_len;
	}

	response_len = ec_i2c_count_response(i2c_msgs, num);
	if (response_len < 0) {
	/* Unexpected; no errors should come when NULL response */
	dev_warn(dev, "Error preparing response %d\n", response_len);
	return response_len;
	}

	alloc_size = max(request_len, response_len);
	msg = kmalloc(sizeof(*msg) + alloc_size, GFP_KERNEL);
	if (!msg)
	return -ENOMEM;

	result = ec_i2c_construct_message(msg->data, i2c_msgs, num, bus_num);
	if (result) {
	dev_err(dev, "Error constructing EC i2c message %d\n", result);
	goto exit;
	}

	msg->version = 0;
	msg->command = EC_CMD_I2C_PASSTHRU;
	msg->outsize = request_len;
	msg->insize = response_len;

	result = cros_ec_cmd_xfer_status(bus->ec, msg);
	if (result < 0) {
	dev_err(dev, "Error transferring EC i2c message %d\n", result);
	goto exit;
	}

	result = ec_i2c_parse_response(msg->data, i2c_msgs, &num);
	if (result < 0) {
	dev_err(dev, "Error parsing EC i2c message %d\n", result);
	goto exit;
	}

	/* Indicate success by saying how many messages were sent */
	result = num;
	exit:
	kfree(msg);
	return result;
	}

	static u32 ec_i2c_functionality(struct i2c_adapter *adap)
	{
	return I2C_FUNC_I2C \| I2C_FUNC_SMBUS_EMUL;
	}

	static const struct i2c_algorithm ec_i2c_algorithm = {
	.master_xfer = ec_i2c_xfer,
	.functionality = ec_i2c_functionality,
	};

	static int ec_i2c_probe(struct platform_device *pdev)
	{
	struct device_node *np = pdev->dev.of_node;
	struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent);
	struct device *dev = &pdev->dev;
	struct ec_i2c_device *bus = NULL;
	u32 remote_bus;
	int err;

	if (!ec->cmd_xfer) {
	dev_err(dev, "Missing sendrecv\n");
	return -EINVAL;
	}

	bus = devm_kzalloc(dev, sizeof(*bus), GFP_KERNEL);
	if (bus == NULL)
	return -ENOMEM;

	err = of_property_read_u32(np, "google,remote-bus", &remote_bus);
	if (err) {
	dev_err(dev, "Couldn't read remote-bus property\n");
	return err;
	}
	bus->remote_bus = remote_bus;

	bus->ec = ec;
	bus->dev = dev;

	bus->adap.owner = THIS_MODULE;
	strlcpy(bus->adap.name, "cros-ec-i2c-tunnel", sizeof(bus->adap.name));
	bus->adap.algo = &ec_i2c_algorithm;
	bus->adap.algo_data = bus;
	bus->adap.dev.parent = &pdev->dev;
	bus->adap.dev.of_node = np;
	bus->adap.retries = I2C_MAX_RETRIES;

	err = i2c_add_adapter(&bus->adap);
	if (err) {
	dev_err(dev, "cannot register i2c adapter\n");
	return err;
	}
	platform_set_drvdata(pdev, bus);

	return err;
	}

	static int ec_i2c_remove(struct platform_device *dev)
	{
	struct ec_i2c_device *bus = platform_get_drvdata(dev);

	i2c_del_adapter(&bus->adap);

	return 0;
	}

	#ifdef CONFIG_OF
	static const struct of_device_id cros_ec_i2c_of_match[] = {
	{ .compatible = "google,cros-ec-i2c-tunnel" },
	{},
	};
	MODULE_DEVICE_TABLE(of, cros_ec_i2c_of_match);
	#endif

	static struct platform_driver ec_i2c_tunnel_driver = {
	.probe = ec_i2c_probe,
	.remove = ec_i2c_remove,
	.driver = {
	.name = "cros-ec-i2c-tunnel",
	.of_match_table = of_match_ptr(cros_ec_i2c_of_match),
	},
	};

	module_platform_driver(ec_i2c_tunnel_driver);

	MODULE_LICENSE("GPL");
	MODULE_DESCRIPTION("EC I2C tunnel driver");
	MODULE_ALIAS("platform:cros-ec-i2c-tunnel");