| // SPDX-License-Identifier: GPL-2.0+ |
| // Expose an I2C passthrough to the ChromeOS EC. |
| // |
| // Copyright (C) 2013 Google, Inc. |
| |
| #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 = ¶ms->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_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 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) |
| 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"); |