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 3 |
15 | |
16 | /** |
17 | * struct ec_i2c_device - Driver data for I2C tunnel |
18 | * |
19 | * @dev: Device node |
20 | * @adap: I2C adapter |
21 | * @ec: Pointer to EC device |
22 | * @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 | |
27 | struct 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_message |
40 | * |
41 | * @i2c_msgs: The i2c messages to read |
42 | * @num: The number of i2c messages. |
43 | * |
44 | * Returns the number of bytes the messages will take up. |
45 | */ |
46 | static 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 EC |
62 | * |
63 | * This function effectively stuffs the standard i2c_msg format of Linux into |
64 | * 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 | */ |
73 | static 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_response |
109 | * |
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 | */ |
115 | static 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 EC |
130 | * |
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 actual |
136 | * number received. |
137 | * |
138 | * Returns 0 or a negative error number. |
139 | */ |
140 | static 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 | |
174 | static 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(size: sizeof(*msg) + alloc_size, GFP_KERNEL); |
201 | if (!msg) |
202 | return -ENOMEM; |
203 | |
204 | result = ec_i2c_construct_message(buf: 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(ec_dev: 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(buf: msg->data, i2c_msgs, num: &num); |
222 | if (result < 0) |
223 | goto exit; |
224 | |
225 | /* Indicate success by saying how many messages were sent */ |
226 | result = num; |
227 | exit: |
228 | kfree(objp: msg); |
229 | return result; |
230 | } |
231 | |
232 | static u32 ec_i2c_functionality(struct i2c_adapter *adap) |
233 | { |
234 | return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL; |
235 | } |
236 | |
237 | static const struct i2c_algorithm ec_i2c_algorithm = { |
238 | .master_xfer = ec_i2c_xfer, |
239 | .functionality = ec_i2c_functionality, |
240 | }; |
241 | |
242 | static int ec_i2c_probe(struct platform_device *pdev) |
243 | { |
244 | struct cros_ec_device *ec = dev_get_drvdata(dev: 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, size: sizeof(*bus), GFP_KERNEL); |
256 | if (bus == NULL) |
257 | return -ENOMEM; |
258 | |
259 | err = device_property_read_u32(dev, propname: "google,remote-bus" , val: &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(p: bus->adap.name, q: "cros-ec-i2c-tunnel" , size: 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(adap: &bus->adap); |
279 | if (err) |
280 | return err; |
281 | platform_set_drvdata(pdev, data: bus); |
282 | |
283 | return err; |
284 | } |
285 | |
286 | static void ec_i2c_remove(struct platform_device *dev) |
287 | { |
288 | struct ec_i2c_device *bus = platform_get_drvdata(pdev: dev); |
289 | |
290 | i2c_del_adapter(adap: &bus->adap); |
291 | } |
292 | |
293 | static const struct of_device_id cros_ec_i2c_of_match[] __maybe_unused = { |
294 | { .compatible = "google,cros-ec-i2c-tunnel" }, |
295 | {}, |
296 | }; |
297 | MODULE_DEVICE_TABLE(of, cros_ec_i2c_of_match); |
298 | |
299 | static const struct acpi_device_id cros_ec_i2c_tunnel_acpi_id[] __maybe_unused = { |
300 | { "GOOG0012" , 0 }, |
301 | { } |
302 | }; |
303 | MODULE_DEVICE_TABLE(acpi, cros_ec_i2c_tunnel_acpi_id); |
304 | |
305 | static 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 | |
315 | module_platform_driver(ec_i2c_tunnel_driver); |
316 | |
317 | MODULE_LICENSE("GPL" ); |
318 | MODULE_DESCRIPTION("EC I2C tunnel driver" ); |
319 | MODULE_ALIAS("platform:cros-ec-i2c-tunnel" ); |
320 | |