dm thin metadata: fix __udivdi3 undefined on 32-bit
[linux/fpc-iii.git] / drivers / i2c / busses / i2c-cros-ec-tunnel.c
blob2d5ff86398d0911cd0c3a261fb689cf2c9e04609
1 /*
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
21 /**
22 * struct ec_i2c_device - Driver data for I2C tunnel
24 * @dev: Device node
25 * @adap: I2C adapter
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 {
33 struct device *dev;
34 struct i2c_adapter adap;
35 struct cros_ec_device *ec;
37 u16 remote_bus;
39 u8 request_buf[256];
40 u8 response_buf[256];
43 /**
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)
53 int i;
54 int size;
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;
62 return size;
65 /**
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[],
79 int num, u16 bus_num)
81 struct ec_params_i2c_passthru *params;
82 u8 *out_data;
83 int i;
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 = &params->msg[i];
95 msg->len = i2c_msg->len;
96 msg->addr_flags = i2c_msg->addr;
98 if (i2c_msg->flags & I2C_M_TEN)
99 return -EINVAL;
101 if (i2c_msg->flags & I2C_M_RD) {
102 msg->addr_flags |= EC_I2C_FLAG_READ;
103 } else {
104 memcpy(out_data, i2c_msg->buf, msg->len);
105 out_data += msg->len;
109 return 0;
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)
122 int size;
123 int i;
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;
130 return size;
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
141 * number received.
143 * Returns 0 or a negative error number.
145 static int ec_i2c_parse_response(const u8 *buf, struct i2c_msg i2c_msgs[],
146 int *num)
148 const struct ec_response_i2c_passthru *resp;
149 const u8 *in_data;
150 int i;
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)
156 return -ETIMEDOUT;
157 else if (resp->i2c_status & EC_I2C_STATUS_ERROR)
158 return -EREMOTEIO;
160 /* Other side could send us back fewer messages, but not more */
161 if (resp->num_msgs > *num)
162 return -EPROTO;
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;
174 return 0;
177 static int ec_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg i2c_msgs[],
178 int num)
180 struct ec_i2c_device *bus = adap->algo_data;
181 struct device *dev = bus->dev;
182 const u16 bus_num = bus->remote_bus;
183 int request_len;
184 int response_len;
185 int alloc_size;
186 int result;
187 struct cros_ec_command *msg;
189 request_len = ec_i2c_count_message(i2c_msgs, num);
190 if (request_len < 0) {
191 dev_warn(dev, "Error constructing message %d\n", request_len);
192 return request_len;
195 response_len = ec_i2c_count_response(i2c_msgs, num);
196 if (response_len < 0) {
197 /* Unexpected; no errors should come when NULL response */
198 dev_warn(dev, "Error preparing response %d\n", response_len);
199 return response_len;
202 alloc_size = max(request_len, response_len);
203 msg = kmalloc(sizeof(*msg) + alloc_size, GFP_KERNEL);
204 if (!msg)
205 return -ENOMEM;
207 result = ec_i2c_construct_message(msg->data, i2c_msgs, num, bus_num);
208 if (result) {
209 dev_err(dev, "Error constructing EC i2c message %d\n", result);
210 goto exit;
213 msg->version = 0;
214 msg->command = EC_CMD_I2C_PASSTHRU;
215 msg->outsize = request_len;
216 msg->insize = response_len;
218 result = cros_ec_cmd_xfer_status(bus->ec, msg);
219 if (result < 0) {
220 dev_err(dev, "Error transferring EC i2c message %d\n", result);
221 goto exit;
224 result = ec_i2c_parse_response(msg->data, i2c_msgs, &num);
225 if (result < 0) {
226 dev_err(dev, "Error parsing EC i2c message %d\n", result);
227 goto exit;
230 /* Indicate success by saying how many messages were sent */
231 result = num;
232 exit:
233 kfree(msg);
234 return result;
237 static u32 ec_i2c_functionality(struct i2c_adapter *adap)
239 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
242 static const struct i2c_algorithm ec_i2c_algorithm = {
243 .master_xfer = ec_i2c_xfer,
244 .functionality = ec_i2c_functionality,
247 static int ec_i2c_probe(struct platform_device *pdev)
249 struct device_node *np = pdev->dev.of_node;
250 struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent);
251 struct device *dev = &pdev->dev;
252 struct ec_i2c_device *bus = NULL;
253 u32 remote_bus;
254 int err;
256 if (!ec->cmd_xfer) {
257 dev_err(dev, "Missing sendrecv\n");
258 return -EINVAL;
261 bus = devm_kzalloc(dev, sizeof(*bus), GFP_KERNEL);
262 if (bus == NULL)
263 return -ENOMEM;
265 err = of_property_read_u32(np, "google,remote-bus", &remote_bus);
266 if (err) {
267 dev_err(dev, "Couldn't read remote-bus property\n");
268 return err;
270 bus->remote_bus = remote_bus;
272 bus->ec = ec;
273 bus->dev = dev;
275 bus->adap.owner = THIS_MODULE;
276 strlcpy(bus->adap.name, "cros-ec-i2c-tunnel", sizeof(bus->adap.name));
277 bus->adap.algo = &ec_i2c_algorithm;
278 bus->adap.algo_data = bus;
279 bus->adap.dev.parent = &pdev->dev;
280 bus->adap.dev.of_node = np;
281 bus->adap.retries = I2C_MAX_RETRIES;
283 err = i2c_add_adapter(&bus->adap);
284 if (err) {
285 dev_err(dev, "cannot register i2c adapter\n");
286 return err;
288 platform_set_drvdata(pdev, bus);
290 return err;
293 static int ec_i2c_remove(struct platform_device *dev)
295 struct ec_i2c_device *bus = platform_get_drvdata(dev);
297 i2c_del_adapter(&bus->adap);
299 return 0;
302 #ifdef CONFIG_OF
303 static const struct of_device_id cros_ec_i2c_of_match[] = {
304 { .compatible = "google,cros-ec-i2c-tunnel" },
307 MODULE_DEVICE_TABLE(of, cros_ec_i2c_of_match);
308 #endif
310 static struct platform_driver ec_i2c_tunnel_driver = {
311 .probe = ec_i2c_probe,
312 .remove = ec_i2c_remove,
313 .driver = {
314 .name = "cros-ec-i2c-tunnel",
315 .of_match_table = of_match_ptr(cros_ec_i2c_of_match),
319 module_platform_driver(ec_i2c_tunnel_driver);
321 MODULE_LICENSE("GPL");
322 MODULE_DESCRIPTION("EC I2C tunnel driver");
323 MODULE_ALIAS("platform:cros-ec-i2c-tunnel");