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  * @ept: The rpmsg endpoint of this channel.
42  * @has_pending_host_event: Boolean used to check if there is a pending event.
43  * @probe_done: Flag to indicate that probe is done.
44  */
45 struct cros_ec_rpmsg {
46 	struct rpmsg_device *rpdev;
47 	struct completion xfer_ack;
48 	struct work_struct host_event_work;
49 	struct rpmsg_endpoint *ept;
50 	bool has_pending_host_event;
51 	bool probe_done;
52 };
53 
54 /**
55  * cros_ec_cmd_xfer_rpmsg - Transfer a message over rpmsg and receive the reply
56  *
57  * @ec_dev: ChromeOS EC device
58  * @ec_msg: Message to transfer
59  *
60  * This is only used for old EC proto version, and is not supported for this
61  * driver.
62  *
63  * Return: -EINVAL
64  */
cros_ec_cmd_xfer_rpmsg(struct cros_ec_device * ec_dev,struct cros_ec_command * ec_msg)65 static int cros_ec_cmd_xfer_rpmsg(struct cros_ec_device *ec_dev,
66 				  struct cros_ec_command *ec_msg)
67 {
68 	return -EINVAL;
69 }
70 
71 /**
72  * cros_ec_pkt_xfer_rpmsg - Transfer a packet over rpmsg and receive the reply
73  *
74  * @ec_dev: ChromeOS EC device
75  * @ec_msg: Message to transfer
76  *
77  * Return: number of bytes of the reply on success or negative error code.
78  */
cros_ec_pkt_xfer_rpmsg(struct cros_ec_device * ec_dev,struct cros_ec_command * ec_msg)79 static int cros_ec_pkt_xfer_rpmsg(struct cros_ec_device *ec_dev,
80 				  struct cros_ec_command *ec_msg)
81 {
82 	struct cros_ec_rpmsg *ec_rpmsg = ec_dev->priv;
83 	struct ec_host_response *response;
84 	unsigned long timeout;
85 	int len;
86 	int ret;
87 	u8 sum;
88 	int i;
89 
90 	ec_msg->result = 0;
91 	len = cros_ec_prepare_tx(ec_dev, ec_msg);
92 	if (len < 0)
93 		return len;
94 	dev_dbg(ec_dev->dev, "prepared, len=%d\n", len);
95 
96 	reinit_completion(&ec_rpmsg->xfer_ack);
97 	ret = rpmsg_send(ec_rpmsg->ept, ec_dev->dout, len);
98 	if (ret) {
99 		dev_err(ec_dev->dev, "rpmsg send failed\n");
100 		return ret;
101 	}
102 
103 	timeout = msecs_to_jiffies(EC_MSG_TIMEOUT_MS);
104 	ret = wait_for_completion_timeout(&ec_rpmsg->xfer_ack, timeout);
105 	if (!ret) {
106 		dev_err(ec_dev->dev, "rpmsg send timeout\n");
107 		return -EIO;
108 	}
109 
110 	/* check response error code */
111 	response = (struct ec_host_response *)ec_dev->din;
112 	ec_msg->result = response->result;
113 
114 	ret = cros_ec_check_result(ec_dev, ec_msg);
115 	if (ret)
116 		goto exit;
117 
118 	if (response->data_len > ec_msg->insize) {
119 		dev_err(ec_dev->dev, "packet too long (%d bytes, expected %d)",
120 			response->data_len, ec_msg->insize);
121 		ret = -EMSGSIZE;
122 		goto exit;
123 	}
124 
125 	/* copy response packet payload and compute checksum */
126 	memcpy(ec_msg->data, ec_dev->din + sizeof(*response),
127 	       response->data_len);
128 
129 	sum = 0;
130 	for (i = 0; i < sizeof(*response) + response->data_len; i++)
131 		sum += ec_dev->din[i];
132 
133 	if (sum) {
134 		dev_err(ec_dev->dev, "bad packet checksum, calculated %x\n",
135 			sum);
136 		ret = -EBADMSG;
137 		goto exit;
138 	}
139 
140 	ret = response->data_len;
141 exit:
142 	if (ec_msg->command == EC_CMD_REBOOT_EC)
143 		msleep(EC_REBOOT_DELAY_MS);
144 
145 	return ret;
146 }
147 
148 static void
cros_ec_rpmsg_host_event_function(struct work_struct * host_event_work)149 cros_ec_rpmsg_host_event_function(struct work_struct *host_event_work)
150 {
151 	struct cros_ec_rpmsg *ec_rpmsg = container_of(host_event_work,
152 						      struct cros_ec_rpmsg,
153 						      host_event_work);
154 
155 	cros_ec_irq_thread(0, dev_get_drvdata(&ec_rpmsg->rpdev->dev));
156 }
157 
cros_ec_rpmsg_callback(struct rpmsg_device * rpdev,void * data,int len,void * priv,u32 src)158 static int cros_ec_rpmsg_callback(struct rpmsg_device *rpdev, void *data,
159 				  int len, void *priv, u32 src)
160 {
161 	struct cros_ec_device *ec_dev = dev_get_drvdata(&rpdev->dev);
162 	struct cros_ec_rpmsg *ec_rpmsg = ec_dev->priv;
163 	struct cros_ec_rpmsg_response *resp;
164 
165 	if (!len) {
166 		dev_warn(ec_dev->dev, "rpmsg received empty response");
167 		return -EINVAL;
168 	}
169 
170 	resp = data;
171 	len -= offsetof(struct cros_ec_rpmsg_response, data);
172 	if (resp->type == HOST_COMMAND_MARK) {
173 		if (len > ec_dev->din_size) {
174 			dev_warn(ec_dev->dev,
175 				 "received length %d > din_size %d, truncating",
176 				 len, ec_dev->din_size);
177 			len = ec_dev->din_size;
178 		}
179 
180 		memcpy(ec_dev->din, resp->data, len);
181 		complete(&ec_rpmsg->xfer_ack);
182 	} else if (resp->type == HOST_EVENT_MARK) {
183 		/*
184 		 * If the host event is sent before cros_ec_register is
185 		 * finished, queue the host event.
186 		 */
187 		if (ec_rpmsg->probe_done)
188 			schedule_work(&ec_rpmsg->host_event_work);
189 		else
190 			ec_rpmsg->has_pending_host_event = true;
191 	} else {
192 		dev_warn(ec_dev->dev, "rpmsg received invalid type = %d",
193 			 resp->type);
194 		return -EINVAL;
195 	}
196 
197 	return 0;
198 }
199 
200 static struct rpmsg_endpoint *
cros_ec_rpmsg_create_ept(struct rpmsg_device * rpdev)201 cros_ec_rpmsg_create_ept(struct rpmsg_device *rpdev)
202 {
203 	struct rpmsg_channel_info chinfo = {};
204 
205 	strscpy(chinfo.name, rpdev->id.name, RPMSG_NAME_SIZE);
206 	chinfo.src = rpdev->src;
207 	chinfo.dst = RPMSG_ADDR_ANY;
208 
209 	return rpmsg_create_ept(rpdev, cros_ec_rpmsg_callback, NULL, chinfo);
210 }
211 
cros_ec_rpmsg_probe(struct rpmsg_device * rpdev)212 static int cros_ec_rpmsg_probe(struct rpmsg_device *rpdev)
213 {
214 	struct device *dev = &rpdev->dev;
215 	struct cros_ec_rpmsg *ec_rpmsg;
216 	struct cros_ec_device *ec_dev;
217 	int ret;
218 
219 	ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
220 	if (!ec_dev)
221 		return -ENOMEM;
222 
223 	ec_rpmsg = devm_kzalloc(dev, sizeof(*ec_rpmsg), GFP_KERNEL);
224 	if (!ec_rpmsg)
225 		return -ENOMEM;
226 
227 	ec_dev->dev = dev;
228 	ec_dev->priv = ec_rpmsg;
229 	ec_dev->cmd_xfer = cros_ec_cmd_xfer_rpmsg;
230 	ec_dev->pkt_xfer = cros_ec_pkt_xfer_rpmsg;
231 	ec_dev->phys_name = dev_name(&rpdev->dev);
232 	ec_dev->din_size = sizeof(struct ec_host_response) +
233 			   sizeof(struct ec_response_get_protocol_info);
234 	ec_dev->dout_size = sizeof(struct ec_host_request);
235 	dev_set_drvdata(dev, ec_dev);
236 
237 	ec_rpmsg->rpdev = rpdev;
238 	init_completion(&ec_rpmsg->xfer_ack);
239 	INIT_WORK(&ec_rpmsg->host_event_work,
240 		  cros_ec_rpmsg_host_event_function);
241 
242 	ec_rpmsg->ept = cros_ec_rpmsg_create_ept(rpdev);
243 	if (!ec_rpmsg->ept)
244 		return -ENOMEM;
245 
246 	ret = cros_ec_register(ec_dev);
247 	if (ret < 0) {
248 		rpmsg_destroy_ept(ec_rpmsg->ept);
249 		cancel_work_sync(&ec_rpmsg->host_event_work);
250 		return ret;
251 	}
252 
253 	ec_rpmsg->probe_done = true;
254 
255 	if (ec_rpmsg->has_pending_host_event)
256 		schedule_work(&ec_rpmsg->host_event_work);
257 
258 	return 0;
259 }
260 
cros_ec_rpmsg_remove(struct rpmsg_device * rpdev)261 static void cros_ec_rpmsg_remove(struct rpmsg_device *rpdev)
262 {
263 	struct cros_ec_device *ec_dev = dev_get_drvdata(&rpdev->dev);
264 	struct cros_ec_rpmsg *ec_rpmsg = ec_dev->priv;
265 
266 	cros_ec_unregister(ec_dev);
267 	rpmsg_destroy_ept(ec_rpmsg->ept);
268 	cancel_work_sync(&ec_rpmsg->host_event_work);
269 }
270 
271 #ifdef CONFIG_PM_SLEEP
cros_ec_rpmsg_suspend(struct device * dev)272 static int cros_ec_rpmsg_suspend(struct device *dev)
273 {
274 	struct cros_ec_device *ec_dev = dev_get_drvdata(dev);
275 
276 	return cros_ec_suspend(ec_dev);
277 }
278 
cros_ec_rpmsg_resume(struct device * dev)279 static int cros_ec_rpmsg_resume(struct device *dev)
280 {
281 	struct cros_ec_device *ec_dev = dev_get_drvdata(dev);
282 
283 	return cros_ec_resume(ec_dev);
284 }
285 #endif
286 
287 static SIMPLE_DEV_PM_OPS(cros_ec_rpmsg_pm_ops, cros_ec_rpmsg_suspend,
288 			 cros_ec_rpmsg_resume);
289 
290 static const struct of_device_id cros_ec_rpmsg_of_match[] = {
291 	{ .compatible = "google,cros-ec-rpmsg", },
292 	{ }
293 };
294 MODULE_DEVICE_TABLE(of, cros_ec_rpmsg_of_match);
295 
296 static struct rpmsg_driver cros_ec_driver_rpmsg = {
297 	.drv = {
298 		.name   = "cros-ec-rpmsg",
299 		.of_match_table = cros_ec_rpmsg_of_match,
300 		.pm	= &cros_ec_rpmsg_pm_ops,
301 	},
302 	.probe		= cros_ec_rpmsg_probe,
303 	.remove		= cros_ec_rpmsg_remove,
304 };
305 
306 module_rpmsg_driver(cros_ec_driver_rpmsg);
307 
308 MODULE_LICENSE("GPL v2");
309 MODULE_DESCRIPTION("ChromeOS EC multi function device (rpmsg)");
310