linux/drivers/i2c/busses/i2c-cros-ec-tunnel.c

// SPDX-License-Identifier: GPL-2.0+
// Expose an I2C passthrough to the ChromeOS EC.
//
// Copyright (C) 2013 Google, Inc.

#include <linux/acpi.h>
#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/platform_data/cros_ec_commands.h>
#include <linux/platform_data/cros_ec_proto.h>
#include <linux/platform_device.h>
#include <linux/slab.h>

#define I2C_MAX_RETRIES …

/**
 * 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 { … };

/**
 * 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)
{ … }

/**
 * 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)
{ … }

/**
 * ec_i2c_count_response - Count bytes needed for ec_i2c_parse_response
 *
 * @i2c_msgs: The i2c messages 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)
{ … }

/**
 * 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 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)
{ … }

static int ec_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg i2c_msgs[],
		       int num)
{ … }

static u32 ec_i2c_functionality(struct i2c_adapter *adap)
{ … }

static const struct i2c_algorithm ec_i2c_algorithm = …;

static int ec_i2c_probe(struct platform_device *pdev)
{ … }

static void ec_i2c_remove(struct platform_device *dev)
{ … }

static const struct of_device_id cros_ec_i2c_of_match[] __maybe_unused = …;
MODULE_DEVICE_TABLE(of, cros_ec_i2c_of_match);

static const struct acpi_device_id cros_ec_i2c_tunnel_acpi_id[] __maybe_unused = …;
MODULE_DEVICE_TABLE(acpi, cros_ec_i2c_tunnel_acpi_id);

static struct platform_driver ec_i2c_tunnel_driver = …;

module_platform_driver(…) …;

MODULE_LICENSE(…) …;
MODULE_DESCRIPTION(…) …;
MODULE_ALIAS(…) …;