1 // SPDX-License-Identifier: GPL-2.0
2 //
3 // Copyright 2018 Google LLC.
4 
5 #include <linux/completion.h>
6 #include <linux/delay.h>
7 #include <linux/kernel.h>
8 #include <linux/module.h>
9 #include <linux/of.h>
10 #include <linux/platform_data/cros_ec_commands.h>
11 #include <linux/platform_data/cros_ec_proto.h>
12 #include <linux/platform_device.h>
13 #include <linux/rpmsg.h>
14 #include <linux/slab.h>
15 
16 #include "cros_ec.h"
17 
18 #define EC_MSG_TIMEOUT_MS	200
19 #define HOST_COMMAND_MARK	1
20 #define HOST_EVENT_MARK		2
21 
22 /**
23  * struct cros_ec_rpmsg_response - rpmsg message format from from EC.
24  *
25  * @type:	The type of message, should be either HOST_COMMAND_MARK or
26  *		HOST_EVENT_MARK, representing that the message is a response to
27  *		host command, or a host event.
28  * @data:	ec_host_response for host command.
29  */
30 struct cros_ec_rpmsg_response {
31 	u8 type;
32 	u8 data[] __aligned(4);
33 };
34 
35 /**
36  * struct cros_ec_rpmsg - information about a EC over rpmsg.
37  *
38  * @rpdev:	rpmsg device we are connected to
39  * @xfer_ack:	completion for host command transfer.
40  * @host_event_work:	Work struct for pending host event.
41  */
42 struct cros_ec_rpmsg {
43 	struct rpmsg_device *rpdev;
44 	struct completion xfer_ack;
45 	struct work_struct host_event_work;
46 	struct rpmsg_endpoint *ept;
47 };
48 
49 /**
50  * cros_ec_cmd_xfer_rpmsg - Transfer a message over rpmsg and receive the reply
51  *
52  * @ec_dev: ChromeOS EC device
53  * @ec_msg: Message to transfer
54  *
55  * This is only used for old EC proto version, and is not supported for this
56  * driver.
57  *
58  * Return: -EINVAL
59  */
60 static int cros_ec_cmd_xfer_rpmsg(struct cros_ec_device *ec_dev,
61 				  struct cros_ec_command *ec_msg)
62 {
63 	return -EINVAL;
64 }
65 
66 /**
67  * cros_ec_pkt_xfer_rpmsg - Transfer a packet over rpmsg and receive the reply
68  *
69  * @ec_dev: ChromeOS EC device
70  * @ec_msg: Message to transfer
71  *
72  * Return: number of bytes of the reply on success or negative error code.
73  */
74 static int cros_ec_pkt_xfer_rpmsg(struct cros_ec_device *ec_dev,
75 				  struct cros_ec_command *ec_msg)
76 {
77 	struct cros_ec_rpmsg *ec_rpmsg = ec_dev->priv;
78 	struct ec_host_response *response;
79 	unsigned long timeout;
80 	int len;
81 	int ret;
82 	u8 sum;
83 	int i;
84 
85 	ec_msg->result = 0;
86 	len = cros_ec_prepare_tx(ec_dev, ec_msg);
87 	dev_dbg(ec_dev->dev, "prepared, len=%d\n", len);
88 
89 	reinit_completion(&ec_rpmsg->xfer_ack);
90 	ret = rpmsg_send(ec_rpmsg->ept, ec_dev->dout, len);
91 	if (ret) {
92 		dev_err(ec_dev->dev, "rpmsg send failed\n");
93 		return ret;
94 	}
95 
96 	timeout = msecs_to_jiffies(EC_MSG_TIMEOUT_MS);
97 	ret = wait_for_completion_timeout(&ec_rpmsg->xfer_ack, timeout);
98 	if (!ret) {
99 		dev_err(ec_dev->dev, "rpmsg send timeout\n");
100 		return -EIO;
101 	}
102 
103 	/* check response error code */
104 	response = (struct ec_host_response *)ec_dev->din;
105 	ec_msg->result = response->result;
106 
107 	ret = cros_ec_check_result(ec_dev, ec_msg);
108 	if (ret)
109 		goto exit;
110 
111 	if (response->data_len > ec_msg->insize) {
112 		dev_err(ec_dev->dev, "packet too long (%d bytes, expected %d)",
113 			response->data_len, ec_msg->insize);
114 		ret = -EMSGSIZE;
115 		goto exit;
116 	}
117 
118 	/* copy response packet payload and compute checksum */
119 	memcpy(ec_msg->data, ec_dev->din + sizeof(*response),
120 	       response->data_len);
121 
122 	sum = 0;
123 	for (i = 0; i < sizeof(*response) + response->data_len; i++)
124 		sum += ec_dev->din[i];
125 
126 	if (sum) {
127 		dev_err(ec_dev->dev, "bad packet checksum, calculated %x\n",
128 			sum);
129 		ret = -EBADMSG;
130 		goto exit;
131 	}
132 
133 	ret = response->data_len;
134 exit:
135 	if (ec_msg->command == EC_CMD_REBOOT_EC)
136 		msleep(EC_REBOOT_DELAY_MS);
137 
138 	return ret;
139 }
140 
141 static void
142 cros_ec_rpmsg_host_event_function(struct work_struct *host_event_work)
143 {
144 	struct cros_ec_rpmsg *ec_rpmsg = container_of(host_event_work,
145 						      struct cros_ec_rpmsg,
146 						      host_event_work);
147 	struct cros_ec_device *ec_dev = dev_get_drvdata(&ec_rpmsg->rpdev->dev);
148 	bool ec_has_more_events;
149 
150 	do {
151 		ec_has_more_events = cros_ec_handle_event(ec_dev);
152 	} while (ec_has_more_events);
153 }
154 
155 static int cros_ec_rpmsg_callback(struct rpmsg_device *rpdev, void *data,
156 				  int len, void *priv, u32 src)
157 {
158 	struct cros_ec_device *ec_dev = dev_get_drvdata(&rpdev->dev);
159 	struct cros_ec_rpmsg *ec_rpmsg = ec_dev->priv;
160 	struct cros_ec_rpmsg_response *resp;
161 
162 	if (!len) {
163 		dev_warn(ec_dev->dev, "rpmsg received empty response");
164 		return -EINVAL;
165 	}
166 
167 	resp = data;
168 	len -= offsetof(struct cros_ec_rpmsg_response, data);
169 	if (resp->type == HOST_COMMAND_MARK) {
170 		if (len > ec_dev->din_size) {
171 			dev_warn(ec_dev->dev,
172 				 "received length %d > din_size %d, truncating",
173 				 len, ec_dev->din_size);
174 			len = ec_dev->din_size;
175 		}
176 
177 		memcpy(ec_dev->din, resp->data, len);
178 		complete(&ec_rpmsg->xfer_ack);
179 	} else if (resp->type == HOST_EVENT_MARK) {
180 		schedule_work(&ec_rpmsg->host_event_work);
181 	} else {
182 		dev_warn(ec_dev->dev, "rpmsg received invalid type = %d",
183 			 resp->type);
184 		return -EINVAL;
185 	}
186 
187 	return 0;
188 }
189 
190 static struct rpmsg_endpoint *
191 cros_ec_rpmsg_create_ept(struct rpmsg_device *rpdev)
192 {
193 	struct rpmsg_channel_info chinfo = {};
194 
195 	strscpy(chinfo.name, rpdev->id.name, RPMSG_NAME_SIZE);
196 	chinfo.src = rpdev->src;
197 	chinfo.dst = RPMSG_ADDR_ANY;
198 
199 	return rpmsg_create_ept(rpdev, cros_ec_rpmsg_callback, NULL, chinfo);
200 }
201 
202 static int cros_ec_rpmsg_probe(struct rpmsg_device *rpdev)
203 {
204 	struct device *dev = &rpdev->dev;
205 	struct cros_ec_rpmsg *ec_rpmsg;
206 	struct cros_ec_device *ec_dev;
207 	int ret;
208 
209 	ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
210 	if (!ec_dev)
211 		return -ENOMEM;
212 
213 	ec_rpmsg = devm_kzalloc(dev, sizeof(*ec_rpmsg), GFP_KERNEL);
214 	if (!ec_rpmsg)
215 		return -ENOMEM;
216 
217 	ec_dev->dev = dev;
218 	ec_dev->priv = ec_rpmsg;
219 	ec_dev->cmd_xfer = cros_ec_cmd_xfer_rpmsg;
220 	ec_dev->pkt_xfer = cros_ec_pkt_xfer_rpmsg;
221 	ec_dev->phys_name = dev_name(&rpdev->dev);
222 	ec_dev->din_size = sizeof(struct ec_host_response) +
223 			   sizeof(struct ec_response_get_protocol_info);
224 	ec_dev->dout_size = sizeof(struct ec_host_request);
225 	dev_set_drvdata(dev, ec_dev);
226 
227 	ec_rpmsg->rpdev = rpdev;
228 	init_completion(&ec_rpmsg->xfer_ack);
229 	INIT_WORK(&ec_rpmsg->host_event_work,
230 		  cros_ec_rpmsg_host_event_function);
231 
232 	ec_rpmsg->ept = cros_ec_rpmsg_create_ept(rpdev);
233 	if (!ec_rpmsg->ept)
234 		return -ENOMEM;
235 
236 	ret = cros_ec_register(ec_dev);
237 	if (ret < 0) {
238 		rpmsg_destroy_ept(ec_rpmsg->ept);
239 		cancel_work_sync(&ec_rpmsg->host_event_work);
240 		return ret;
241 	}
242 
243 	return 0;
244 }
245 
246 static void cros_ec_rpmsg_remove(struct rpmsg_device *rpdev)
247 {
248 	struct cros_ec_device *ec_dev = dev_get_drvdata(&rpdev->dev);
249 	struct cros_ec_rpmsg *ec_rpmsg = ec_dev->priv;
250 
251 	cros_ec_unregister(ec_dev);
252 	rpmsg_destroy_ept(ec_rpmsg->ept);
253 	cancel_work_sync(&ec_rpmsg->host_event_work);
254 }
255 
256 #ifdef CONFIG_PM_SLEEP
257 static int cros_ec_rpmsg_suspend(struct device *dev)
258 {
259 	struct cros_ec_device *ec_dev = dev_get_drvdata(dev);
260 
261 	return cros_ec_suspend(ec_dev);
262 }
263 
264 static int cros_ec_rpmsg_resume(struct device *dev)
265 {
266 	struct cros_ec_device *ec_dev = dev_get_drvdata(dev);
267 
268 	return cros_ec_resume(ec_dev);
269 }
270 #endif
271 
272 static SIMPLE_DEV_PM_OPS(cros_ec_rpmsg_pm_ops, cros_ec_rpmsg_suspend,
273 			 cros_ec_rpmsg_resume);
274 
275 static const struct of_device_id cros_ec_rpmsg_of_match[] = {
276 	{ .compatible = "google,cros-ec-rpmsg", },
277 	{ }
278 };
279 MODULE_DEVICE_TABLE(of, cros_ec_rpmsg_of_match);
280 
281 static struct rpmsg_driver cros_ec_driver_rpmsg = {
282 	.drv = {
283 		.name   = "cros-ec-rpmsg",
284 		.of_match_table = cros_ec_rpmsg_of_match,
285 		.pm	= &cros_ec_rpmsg_pm_ops,
286 	},
287 	.probe		= cros_ec_rpmsg_probe,
288 	.remove		= cros_ec_rpmsg_remove,
289 };
290 
291 module_rpmsg_driver(cros_ec_driver_rpmsg);
292 
293 MODULE_LICENSE("GPL v2");
294 MODULE_DESCRIPTION("ChromeOS EC multi function device (rpmsg)");
295