2 * Copyright (C) 2013 Google, Inc
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
9 * Expose an I2C passthrough to the ChromeOS EC.
12 #include <linux/module.h>
13 #include <linux/i2c.h>
14 #include <linux/mfd/cros_ec.h>
15 #include <linux/mfd/cros_ec_commands.h>
16 #include <linux/platform_device.h>
17 #include <linux/slab.h>
19 #define I2C_MAX_RETRIES 3
22 * struct ec_i2c_device - Driver data for I2C tunnel
26 * @ec: Pointer to EC device
27 * @remote_bus: The EC bus number we tunnel to on the other side.
28 * @request_buf: Buffer for transmitting data; we expect most transfers to fit.
29 * @response_buf: Buffer for receiving data; we expect most transfers to fit.
32 struct ec_i2c_device {
34 struct i2c_adapter adap;
35 struct cros_ec_device *ec;
44 * ec_i2c_count_message - Count bytes needed for ec_i2c_construct_message
46 * @i2c_msgs: The i2c messages to read
47 * @num: The number of i2c messages.
49 * Returns the number of bytes the messages will take up.
51 static int ec_i2c_count_message(const struct i2c_msg i2c_msgs[], int num)
56 size = sizeof(struct ec_params_i2c_passthru);
57 size += num * sizeof(struct ec_params_i2c_passthru_msg);
58 for (i = 0; i < num; i++)
59 if (!(i2c_msgs[i].flags & I2C_M_RD))
60 size += i2c_msgs[i].len;
66 * ec_i2c_construct_message - construct a message to go to the EC
68 * This function effectively stuffs the standard i2c_msg format of Linux into
69 * a format that the EC understands.
71 * @buf: The buffer to fill. We assume that the buffer is big enough.
72 * @i2c_msgs: The i2c messages to read.
73 * @num: The number of i2c messages.
74 * @bus_num: The remote bus number we want to talk to.
76 * Returns 0 or a negative error number.
78 static int ec_i2c_construct_message(u8 *buf, const struct i2c_msg i2c_msgs[],
81 struct ec_params_i2c_passthru *params;
85 out_data = buf + sizeof(struct ec_params_i2c_passthru) +
86 num * sizeof(struct ec_params_i2c_passthru_msg);
88 params = (struct ec_params_i2c_passthru *)buf;
89 params->port = bus_num;
90 params->num_msgs = num;
91 for (i = 0; i < num; i++) {
92 const struct i2c_msg *i2c_msg = &i2c_msgs[i];
93 struct ec_params_i2c_passthru_msg *msg = ¶ms->msg[i];
95 msg->len = i2c_msg->len;
96 msg->addr_flags = i2c_msg->addr;
98 if (i2c_msg->flags & I2C_M_TEN)
101 if (i2c_msg->flags & I2C_M_RD) {
102 msg->addr_flags |= EC_I2C_FLAG_READ;
104 memcpy(out_data, i2c_msg->buf, msg->len);
105 out_data += msg->len;
113 * ec_i2c_count_response - Count bytes needed for ec_i2c_parse_response
115 * @i2c_msgs: The i2c messages to to fill up.
116 * @num: The number of i2c messages expected.
118 * Returns the number of response bytes expeced.
120 static int ec_i2c_count_response(struct i2c_msg i2c_msgs[], int num)
125 size = sizeof(struct ec_response_i2c_passthru);
126 for (i = 0; i < num; i++)
127 if (i2c_msgs[i].flags & I2C_M_RD)
128 size += i2c_msgs[i].len;
134 * ec_i2c_parse_response - Parse a response from the EC
136 * We'll take the EC's response and copy it back into msgs.
138 * @buf: The buffer to parse.
139 * @i2c_msgs: The i2c messages to to fill up.
140 * @num: The number of i2c messages; will be modified to include the actual
143 * Returns 0 or a negative error number.
145 static int ec_i2c_parse_response(const u8 *buf, struct i2c_msg i2c_msgs[],
148 const struct ec_response_i2c_passthru *resp;
152 in_data = buf + sizeof(struct ec_response_i2c_passthru);
154 resp = (const struct ec_response_i2c_passthru *)buf;
155 if (resp->i2c_status & EC_I2C_STATUS_TIMEOUT)
157 else if (resp->i2c_status & EC_I2C_STATUS_ERROR)
160 /* Other side could send us back fewer messages, but not more */
161 if (resp->num_msgs > *num)
163 *num = resp->num_msgs;
165 for (i = 0; i < *num; i++) {
166 struct i2c_msg *i2c_msg = &i2c_msgs[i];
168 if (i2c_msgs[i].flags & I2C_M_RD) {
169 memcpy(i2c_msg->buf, in_data, i2c_msg->len);
170 in_data += i2c_msg->len;
177 static int ec_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg i2c_msgs[],
180 struct ec_i2c_device *bus = adap->algo_data;
181 struct device *dev = bus->dev;
182 const u16 bus_num = bus->remote_bus;
188 struct cros_ec_command msg;
190 request_len = ec_i2c_count_message(i2c_msgs, num);
191 if (request_len < 0) {
192 dev_warn(dev, "Error constructing message %d\n", request_len);
193 result = request_len;
196 response_len = ec_i2c_count_response(i2c_msgs, num);
197 if (response_len < 0) {
198 /* Unexpected; no errors should come when NULL response */
199 dev_warn(dev, "Error preparing response %d\n", response_len);
200 result = response_len;
204 if (request_len <= ARRAY_SIZE(bus->request_buf)) {
205 request = bus->request_buf;
207 request = kzalloc(request_len, GFP_KERNEL);
208 if (request == NULL) {
213 if (response_len <= ARRAY_SIZE(bus->response_buf)) {
214 response = bus->response_buf;
216 response = kzalloc(response_len, GFP_KERNEL);
217 if (response == NULL) {
223 result = ec_i2c_construct_message(request, i2c_msgs, num, bus_num);
228 msg.command = EC_CMD_I2C_PASSTHRU;
229 msg.outdata = request;
230 msg.outsize = request_len;
231 msg.indata = response;
232 msg.insize = response_len;
234 result = cros_ec_cmd_xfer(bus->ec, &msg);
238 result = ec_i2c_parse_response(response, i2c_msgs, &num);
242 /* Indicate success by saying how many messages were sent */
245 if (request != bus->request_buf)
247 if (response != bus->response_buf)
253 static u32 ec_i2c_functionality(struct i2c_adapter *adap)
255 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
258 static const struct i2c_algorithm ec_i2c_algorithm = {
259 .master_xfer = ec_i2c_xfer,
260 .functionality = ec_i2c_functionality,
263 static int ec_i2c_probe(struct platform_device *pdev)
265 struct device_node *np = pdev->dev.of_node;
266 struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent);
267 struct device *dev = &pdev->dev;
268 struct ec_i2c_device *bus = NULL;
273 dev_err(dev, "Missing sendrecv\n");
277 bus = devm_kzalloc(dev, sizeof(*bus), GFP_KERNEL);
281 err = of_property_read_u32(np, "google,remote-bus", &remote_bus);
283 dev_err(dev, "Couldn't read remote-bus property\n");
286 bus->remote_bus = remote_bus;
291 bus->adap.owner = THIS_MODULE;
292 strlcpy(bus->adap.name, "cros-ec-i2c-tunnel", sizeof(bus->adap.name));
293 bus->adap.algo = &ec_i2c_algorithm;
294 bus->adap.algo_data = bus;
295 bus->adap.dev.parent = &pdev->dev;
296 bus->adap.dev.of_node = np;
297 bus->adap.retries = I2C_MAX_RETRIES;
299 err = i2c_add_adapter(&bus->adap);
301 dev_err(dev, "cannot register i2c adapter\n");
304 platform_set_drvdata(pdev, bus);
309 static int ec_i2c_remove(struct platform_device *dev)
311 struct ec_i2c_device *bus = platform_get_drvdata(dev);
313 i2c_del_adapter(&bus->adap);
319 static const struct of_device_id cros_ec_i2c_of_match[] = {
320 { .compatible = "google,cros-ec-i2c-tunnel" },
323 MODULE_DEVICE_TABLE(of, cros_ec_i2c_of_match);
326 static struct platform_driver ec_i2c_tunnel_driver = {
327 .probe = ec_i2c_probe,
328 .remove = ec_i2c_remove,
330 .name = "cros-ec-i2c-tunnel",
331 .of_match_table = of_match_ptr(cros_ec_i2c_of_match),
335 module_platform_driver(ec_i2c_tunnel_driver);
337 MODULE_LICENSE("GPL");
338 MODULE_DESCRIPTION("EC I2C tunnel driver");
339 MODULE_ALIAS("platform:cros-ec-i2c-tunnel");