linux/drivers/i2c/busses/i2c-cros-ec-tunnel.c
Wolfram Sang ea1558ce14 i2c: move drivers from strlcpy to strscpy
Follow the advice of the below link and prefer 'strscpy'. Conversion is
easy because no driver used the return value and has been done with a
simple sed invocation.

Link: https://lore.kernel.org/r/CAHk-=wgfRnXz0W3D37d01q3JFkr_i_uTL=V6A6G1oUZcprmknw@mail.gmail.com/
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
2022-08-11 23:02:51 +02:00

322 lines
7.9 KiB
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 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 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 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_NAK)
return -ENXIO;
else if (resp->i2c_status & EC_I2C_STATUS_ERROR)
return -EIO;
/* 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)
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 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 = device_property_read_u32(dev, "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;
strscpy(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 = pdev->dev.of_node;
bus->adap.retries = I2C_MAX_RETRIES;
ACPI_COMPANION_SET(&bus->adap.dev, ACPI_COMPANION(&pdev->dev));
err = i2c_add_adapter(&bus->adap);
if (err)
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;
}
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);
static const struct acpi_device_id cros_ec_i2c_tunnel_acpi_id[] = {
{ "GOOG0012", 0 },
{ }
};
MODULE_DEVICE_TABLE(acpi, cros_ec_i2c_tunnel_acpi_id);
static struct platform_driver ec_i2c_tunnel_driver = {
.probe = ec_i2c_probe,
.remove = ec_i2c_remove,
.driver = {
.name = "cros-ec-i2c-tunnel",
.acpi_match_table = ACPI_PTR(cros_ec_i2c_tunnel_acpi_id),
.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");