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#define EC_MSG_TIMEOUT_MS	200
 17#define HOST_COMMAND_MARK	1
 18#define HOST_EVENT_MARK		2
 19
 20/**
 21 * struct cros_ec_rpmsg_response - rpmsg message format from from EC.
 22 *
 23 * @type:	The type of message, should be either HOST_COMMAND_MARK or
 24 *		HOST_EVENT_MARK, representing that the message is a response to
 25 *		host command, or a host event.
 26 * @data:	ec_host_response for host command.
 27 */
 28struct cros_ec_rpmsg_response {
 29	u8 type;
 30	u8 data[] __aligned(4);
 31};
 32
 33/**
 34 * struct cros_ec_rpmsg - information about a EC over rpmsg.
 35 *
 36 * @rpdev:	rpmsg device we are connected to
 37 * @xfer_ack:	completion for host command transfer.
 38 * @host_event_work:	Work struct for pending host event.
 39 */
 40struct cros_ec_rpmsg {
 41	struct rpmsg_device *rpdev;
 42	struct completion xfer_ack;
 43	struct work_struct host_event_work;
 44	struct rpmsg_endpoint *ept;
 45};
 46
 47/**
 48 * cros_ec_cmd_xfer_rpmsg - Transfer a message over rpmsg and receive the reply
 49 *
 50 * @ec_dev: ChromeOS EC device
 51 * @ec_msg: Message to transfer
 52 *
 53 * This is only used for old EC proto version, and is not supported for this
 54 * driver.
 55 *
 56 * Return: -EINVAL
 57 */
 58static int cros_ec_cmd_xfer_rpmsg(struct cros_ec_device *ec_dev,
 59				  struct cros_ec_command *ec_msg)
 60{
 61	return -EINVAL;
 62}
 63
 64/**
 65 * cros_ec_pkt_xfer_rpmsg - Transfer a packet over rpmsg and receive the reply
 66 *
 67 * @ec_dev: ChromeOS EC device
 68 * @ec_msg: Message to transfer
 69 *
 70 * Return: number of bytes of the reply on success or negative error code.
 71 */
 72static int cros_ec_pkt_xfer_rpmsg(struct cros_ec_device *ec_dev,
 73				  struct cros_ec_command *ec_msg)
 74{
 75	struct cros_ec_rpmsg *ec_rpmsg = ec_dev->priv;
 76	struct ec_host_response *response;
 77	unsigned long timeout;
 78	int len;
 79	int ret;
 80	u8 sum;
 81	int i;
 82
 83	ec_msg->result = 0;
 84	len = cros_ec_prepare_tx(ec_dev, ec_msg);
 85	dev_dbg(ec_dev->dev, "prepared, len=%d\n", len);
 86
 87	reinit_completion(&ec_rpmsg->xfer_ack);
 88	ret = rpmsg_send(ec_rpmsg->ept, ec_dev->dout, len);
 89	if (ret) {
 90		dev_err(ec_dev->dev, "rpmsg send failed\n");
 91		return ret;
 92	}
 93
 94	timeout = msecs_to_jiffies(EC_MSG_TIMEOUT_MS);
 95	ret = wait_for_completion_timeout(&ec_rpmsg->xfer_ack, timeout);
 96	if (!ret) {
 97		dev_err(ec_dev->dev, "rpmsg send timeout\n");
 98		return -EIO;
 99	}
100
101	/* check response error code */
102	response = (struct ec_host_response *)ec_dev->din;
103	ec_msg->result = response->result;
104
105	ret = cros_ec_check_result(ec_dev, ec_msg);
106	if (ret)
107		goto exit;
108
109	if (response->data_len > ec_msg->insize) {
110		dev_err(ec_dev->dev, "packet too long (%d bytes, expected %d)",
111			response->data_len, ec_msg->insize);
112		ret = -EMSGSIZE;
113		goto exit;
114	}
115
116	/* copy response packet payload and compute checksum */
117	memcpy(ec_msg->data, ec_dev->din + sizeof(*response),
118	       response->data_len);
119
120	sum = 0;
121	for (i = 0; i < sizeof(*response) + response->data_len; i++)
122		sum += ec_dev->din[i];
123
124	if (sum) {
125		dev_err(ec_dev->dev, "bad packet checksum, calculated %x\n",
126			sum);
127		ret = -EBADMSG;
128		goto exit;
129	}
130
131	ret = response->data_len;
132exit:
133	if (ec_msg->command == EC_CMD_REBOOT_EC)
134		msleep(EC_REBOOT_DELAY_MS);
135
136	return ret;
137}
138
139static void
140cros_ec_rpmsg_host_event_function(struct work_struct *host_event_work)
141{
142	struct cros_ec_rpmsg *ec_rpmsg = container_of(host_event_work,
143						      struct cros_ec_rpmsg,
144						      host_event_work);
145	struct cros_ec_device *ec_dev = dev_get_drvdata(&ec_rpmsg->rpdev->dev);
146	bool wake_event = true;
147	int ret;
148
149	ret = cros_ec_get_next_event(ec_dev, &wake_event);
150
151	/*
152	 * Signal only if wake host events or any interrupt if
153	 * cros_ec_get_next_event() returned an error (default value for
154	 * wake_event is true)
155	 */
156	if (wake_event && device_may_wakeup(ec_dev->dev))
157		pm_wakeup_event(ec_dev->dev, 0);
158
159	if (ret > 0)
160		blocking_notifier_call_chain(&ec_dev->event_notifier,
161					     0, ec_dev);
162}
163
164static int cros_ec_rpmsg_callback(struct rpmsg_device *rpdev, void *data,
165				  int len, void *priv, u32 src)
166{
167	struct cros_ec_device *ec_dev = dev_get_drvdata(&rpdev->dev);
168	struct cros_ec_rpmsg *ec_rpmsg = ec_dev->priv;
169	struct cros_ec_rpmsg_response *resp;
170
171	if (!len) {
172		dev_warn(ec_dev->dev, "rpmsg received empty response");
173		return -EINVAL;
174	}
175
176	resp = data;
177	len -= offsetof(struct cros_ec_rpmsg_response, data);
178	if (resp->type == HOST_COMMAND_MARK) {
179		if (len > ec_dev->din_size) {
180			dev_warn(ec_dev->dev,
181				 "received length %d > din_size %d, truncating",
182				 len, ec_dev->din_size);
183			len = ec_dev->din_size;
184		}
185
186		memcpy(ec_dev->din, resp->data, len);
187		complete(&ec_rpmsg->xfer_ack);
188	} else if (resp->type == HOST_EVENT_MARK) {
189		schedule_work(&ec_rpmsg->host_event_work);
190	} else {
191		dev_warn(ec_dev->dev, "rpmsg received invalid type = %d",
192			 resp->type);
193		return -EINVAL;
194	}
195
196	return 0;
197}
198
199static struct rpmsg_endpoint *
200cros_ec_rpmsg_create_ept(struct rpmsg_device *rpdev)
201{
202	struct rpmsg_channel_info chinfo = {};
203
204	strscpy(chinfo.name, rpdev->id.name, RPMSG_NAME_SIZE);
205	chinfo.src = rpdev->src;
206	chinfo.dst = RPMSG_ADDR_ANY;
207
208	return rpmsg_create_ept(rpdev, cros_ec_rpmsg_callback, NULL, chinfo);
209}
210
211static int cros_ec_rpmsg_probe(struct rpmsg_device *rpdev)
212{
213	struct device *dev = &rpdev->dev;
214	struct cros_ec_rpmsg *ec_rpmsg;
215	struct cros_ec_device *ec_dev;
216	int ret;
217
218	ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
219	if (!ec_dev)
220		return -ENOMEM;
221
222	ec_rpmsg = devm_kzalloc(dev, sizeof(*ec_rpmsg), GFP_KERNEL);
223	if (!ec_rpmsg)
224		return -ENOMEM;
225
226	ec_dev->dev = dev;
227	ec_dev->priv = ec_rpmsg;
228	ec_dev->cmd_xfer = cros_ec_cmd_xfer_rpmsg;
229	ec_dev->pkt_xfer = cros_ec_pkt_xfer_rpmsg;
230	ec_dev->phys_name = dev_name(&rpdev->dev);
231	ec_dev->din_size = sizeof(struct ec_host_response) +
232			   sizeof(struct ec_response_get_protocol_info);
233	ec_dev->dout_size = sizeof(struct ec_host_request);
234	dev_set_drvdata(dev, ec_dev);
235
236	ec_rpmsg->rpdev = rpdev;
237	init_completion(&ec_rpmsg->xfer_ack);
238	INIT_WORK(&ec_rpmsg->host_event_work,
239		  cros_ec_rpmsg_host_event_function);
240
241	ec_rpmsg->ept = cros_ec_rpmsg_create_ept(rpdev);
242	if (!ec_rpmsg->ept)
243		return -ENOMEM;
244
245	ret = cros_ec_register(ec_dev);
246	if (ret < 0) {
247		rpmsg_destroy_ept(ec_rpmsg->ept);
248		cancel_work_sync(&ec_rpmsg->host_event_work);
249		return ret;
250	}
251
252	return 0;
253}
254
255static void cros_ec_rpmsg_remove(struct rpmsg_device *rpdev)
256{
257	struct cros_ec_device *ec_dev = dev_get_drvdata(&rpdev->dev);
258	struct cros_ec_rpmsg *ec_rpmsg = ec_dev->priv;
259
260	cros_ec_unregister(ec_dev);
261	rpmsg_destroy_ept(ec_rpmsg->ept);
262	cancel_work_sync(&ec_rpmsg->host_event_work);
263}
264
265#ifdef CONFIG_PM_SLEEP
266static int cros_ec_rpmsg_suspend(struct device *dev)
267{
268	struct cros_ec_device *ec_dev = dev_get_drvdata(dev);
269
270	return cros_ec_suspend(ec_dev);
271}
272
273static int cros_ec_rpmsg_resume(struct device *dev)
274{
275	struct cros_ec_device *ec_dev = dev_get_drvdata(dev);
276
277	return cros_ec_resume(ec_dev);
278}
279#endif
280
281static SIMPLE_DEV_PM_OPS(cros_ec_rpmsg_pm_ops, cros_ec_rpmsg_suspend,
282			 cros_ec_rpmsg_resume);
283
284static const struct of_device_id cros_ec_rpmsg_of_match[] = {
285	{ .compatible = "google,cros-ec-rpmsg", },
286	{ }
287};
288MODULE_DEVICE_TABLE(of, cros_ec_rpmsg_of_match);
289
290static struct rpmsg_driver cros_ec_driver_rpmsg = {
291	.drv = {
292		.name   = "cros-ec-rpmsg",
293		.of_match_table = cros_ec_rpmsg_of_match,
294		.pm	= &cros_ec_rpmsg_pm_ops,
295	},
296	.probe		= cros_ec_rpmsg_probe,
297	.remove		= cros_ec_rpmsg_remove,
298};
299
300module_rpmsg_driver(cros_ec_driver_rpmsg);
301
302MODULE_LICENSE("GPL v2");
303MODULE_DESCRIPTION("ChromeOS EC multi function device (rpmsg)");