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1// SPDX-License-Identifier: GPL-2.0+2// Expose an I2C passthrough to the ChromeOS EC.3//4// Copyright (C) 2013 Google, Inc.5 6#include <linux/acpi.h>7#include <linux/module.h>8#include <linux/i2c.h>9#include <linux/platform_data/cros_ec_commands.h>10#include <linux/platform_data/cros_ec_proto.h>11#include <linux/platform_device.h>12#include <linux/slab.h>13 14#define I2C_MAX_RETRIES 315 16/**17 * struct ec_i2c_device - Driver data for I2C tunnel18 *19 * @dev: Device node20 * @adap: I2C adapter21 * @ec: Pointer to EC device22 * @remote_bus: The EC bus number we tunnel to on the other side.23 * @request_buf: Buffer for transmitting data; we expect most transfers to fit.24 * @response_buf: Buffer for receiving data; we expect most transfers to fit.25 */26 27struct ec_i2c_device {28 struct device *dev;29 struct i2c_adapter adap;30 struct cros_ec_device *ec;31 32 u16 remote_bus;33 34 u8 request_buf[256];35 u8 response_buf[256];36};37 38/**39 * ec_i2c_count_message - Count bytes needed for ec_i2c_construct_message40 *41 * @i2c_msgs: The i2c messages to read42 * @num: The number of i2c messages.43 *44 * Returns the number of bytes the messages will take up.45 */46static int ec_i2c_count_message(const struct i2c_msg i2c_msgs[], int num)47{48 int i;49 int size;50 51 size = sizeof(struct ec_params_i2c_passthru);52 size += num * sizeof(struct ec_params_i2c_passthru_msg);53 for (i = 0; i < num; i++)54 if (!(i2c_msgs[i].flags & I2C_M_RD))55 size += i2c_msgs[i].len;56 57 return size;58}59 60/**61 * ec_i2c_construct_message - construct a message to go to the EC62 *63 * This function effectively stuffs the standard i2c_msg format of Linux into64 * a format that the EC understands.65 *66 * @buf: The buffer to fill. We assume that the buffer is big enough.67 * @i2c_msgs: The i2c messages to read.68 * @num: The number of i2c messages.69 * @bus_num: The remote bus number we want to talk to.70 *71 * Returns 0 or a negative error number.72 */73static int ec_i2c_construct_message(u8 *buf, const struct i2c_msg i2c_msgs[],74 int num, u16 bus_num)75{76 struct ec_params_i2c_passthru *params;77 u8 *out_data;78 int i;79 80 out_data = buf + sizeof(struct ec_params_i2c_passthru) +81 num * sizeof(struct ec_params_i2c_passthru_msg);82 83 params = (struct ec_params_i2c_passthru *)buf;84 params->port = bus_num;85 params->num_msgs = num;86 for (i = 0; i < num; i++) {87 const struct i2c_msg *i2c_msg = &i2c_msgs[i];88 struct ec_params_i2c_passthru_msg *msg = ¶ms->msg[i];89 90 msg->len = i2c_msg->len;91 msg->addr_flags = i2c_msg->addr;92 93 if (i2c_msg->flags & I2C_M_TEN)94 return -EINVAL;95 96 if (i2c_msg->flags & I2C_M_RD) {97 msg->addr_flags |= EC_I2C_FLAG_READ;98 } else {99 memcpy(out_data, i2c_msg->buf, msg->len);100 out_data += msg->len;101 }102 }103 104 return 0;105}106 107/**108 * ec_i2c_count_response - Count bytes needed for ec_i2c_parse_response109 *110 * @i2c_msgs: The i2c messages to fill up.111 * @num: The number of i2c messages expected.112 *113 * Returns the number of response bytes expeced.114 */115static int ec_i2c_count_response(struct i2c_msg i2c_msgs[], int num)116{117 int size;118 int i;119 120 size = sizeof(struct ec_response_i2c_passthru);121 for (i = 0; i < num; i++)122 if (i2c_msgs[i].flags & I2C_M_RD)123 size += i2c_msgs[i].len;124 125 return size;126}127 128/**129 * ec_i2c_parse_response - Parse a response from the EC130 *131 * We'll take the EC's response and copy it back into msgs.132 *133 * @buf: The buffer to parse.134 * @i2c_msgs: The i2c messages to fill up.135 * @num: The number of i2c messages; will be modified to include the actual136 * number received.137 *138 * Returns 0 or a negative error number.139 */140static int ec_i2c_parse_response(const u8 *buf, struct i2c_msg i2c_msgs[],141 int *num)142{143 const struct ec_response_i2c_passthru *resp;144 const u8 *in_data;145 int i;146 147 in_data = buf + sizeof(struct ec_response_i2c_passthru);148 149 resp = (const struct ec_response_i2c_passthru *)buf;150 if (resp->i2c_status & EC_I2C_STATUS_TIMEOUT)151 return -ETIMEDOUT;152 else if (resp->i2c_status & EC_I2C_STATUS_NAK)153 return -ENXIO;154 else if (resp->i2c_status & EC_I2C_STATUS_ERROR)155 return -EIO;156 157 /* Other side could send us back fewer messages, but not more */158 if (resp->num_msgs > *num)159 return -EPROTO;160 *num = resp->num_msgs;161 162 for (i = 0; i < *num; i++) {163 struct i2c_msg *i2c_msg = &i2c_msgs[i];164 165 if (i2c_msgs[i].flags & I2C_M_RD) {166 memcpy(i2c_msg->buf, in_data, i2c_msg->len);167 in_data += i2c_msg->len;168 }169 }170 171 return 0;172}173 174static int ec_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg i2c_msgs[],175 int num)176{177 struct ec_i2c_device *bus = adap->algo_data;178 struct device *dev = bus->dev;179 const u16 bus_num = bus->remote_bus;180 int request_len;181 int response_len;182 int alloc_size;183 int result;184 struct cros_ec_command *msg;185 186 request_len = ec_i2c_count_message(i2c_msgs, num);187 if (request_len < 0) {188 dev_warn(dev, "Error constructing message %d\n", request_len);189 return request_len;190 }191 192 response_len = ec_i2c_count_response(i2c_msgs, num);193 if (response_len < 0) {194 /* Unexpected; no errors should come when NULL response */195 dev_warn(dev, "Error preparing response %d\n", response_len);196 return response_len;197 }198 199 alloc_size = max(request_len, response_len);200 msg = kmalloc(sizeof(*msg) + alloc_size, GFP_KERNEL);201 if (!msg)202 return -ENOMEM;203 204 result = ec_i2c_construct_message(msg->data, i2c_msgs, num, bus_num);205 if (result) {206 dev_err(dev, "Error constructing EC i2c message %d\n", result);207 goto exit;208 }209 210 msg->version = 0;211 msg->command = EC_CMD_I2C_PASSTHRU;212 msg->outsize = request_len;213 msg->insize = response_len;214 215 result = cros_ec_cmd_xfer_status(bus->ec, msg);216 if (result < 0) {217 dev_err(dev, "Error transferring EC i2c message %d\n", result);218 goto exit;219 }220 221 result = ec_i2c_parse_response(msg->data, i2c_msgs, &num);222 if (result < 0)223 goto exit;224 225 /* Indicate success by saying how many messages were sent */226 result = num;227exit:228 kfree(msg);229 return result;230}231 232static u32 ec_i2c_functionality(struct i2c_adapter *adap)233{234 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;235}236 237static const struct i2c_algorithm ec_i2c_algorithm = {238 .xfer = ec_i2c_xfer,239 .functionality = ec_i2c_functionality,240};241 242static int ec_i2c_probe(struct platform_device *pdev)243{244 struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent);245 struct device *dev = &pdev->dev;246 struct ec_i2c_device *bus = NULL;247 u32 remote_bus;248 int err;249 250 if (!ec->cmd_xfer) {251 dev_err(dev, "Missing sendrecv\n");252 return -EINVAL;253 }254 255 bus = devm_kzalloc(dev, sizeof(*bus), GFP_KERNEL);256 if (bus == NULL)257 return -ENOMEM;258 259 err = device_property_read_u32(dev, "google,remote-bus", &remote_bus);260 if (err) {261 dev_err(dev, "Couldn't read remote-bus property\n");262 return err;263 }264 bus->remote_bus = remote_bus;265 266 bus->ec = ec;267 bus->dev = dev;268 269 bus->adap.owner = THIS_MODULE;270 strscpy(bus->adap.name, "cros-ec-i2c-tunnel", sizeof(bus->adap.name));271 bus->adap.algo = &ec_i2c_algorithm;272 bus->adap.algo_data = bus;273 bus->adap.dev.parent = &pdev->dev;274 bus->adap.dev.of_node = pdev->dev.of_node;275 bus->adap.retries = I2C_MAX_RETRIES;276 ACPI_COMPANION_SET(&bus->adap.dev, ACPI_COMPANION(&pdev->dev));277 278 err = i2c_add_adapter(&bus->adap);279 if (err)280 return err;281 platform_set_drvdata(pdev, bus);282 283 return err;284}285 286static void ec_i2c_remove(struct platform_device *dev)287{288 struct ec_i2c_device *bus = platform_get_drvdata(dev);289 290 i2c_del_adapter(&bus->adap);291}292 293static const struct of_device_id cros_ec_i2c_of_match[] __maybe_unused = {294 { .compatible = "google,cros-ec-i2c-tunnel" },295 {},296};297MODULE_DEVICE_TABLE(of, cros_ec_i2c_of_match);298 299static const struct acpi_device_id cros_ec_i2c_tunnel_acpi_id[] __maybe_unused = {300 { "GOOG0012", 0 },301 { }302};303MODULE_DEVICE_TABLE(acpi, cros_ec_i2c_tunnel_acpi_id);304 305static struct platform_driver ec_i2c_tunnel_driver = {306 .probe = ec_i2c_probe,307 .remove_new = ec_i2c_remove,308 .driver = {309 .name = "cros-ec-i2c-tunnel",310 .acpi_match_table = ACPI_PTR(cros_ec_i2c_tunnel_acpi_id),311 .of_match_table = of_match_ptr(cros_ec_i2c_of_match),312 },313};314 315module_platform_driver(ec_i2c_tunnel_driver);316 317MODULE_LICENSE("GPL");318MODULE_DESCRIPTION("EC I2C tunnel driver");319MODULE_ALIAS("platform:cros-ec-i2c-tunnel");320