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 */
 30struct 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 */
 45struct 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 */
 65static 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 */
 79static 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	dev_dbg(ec_dev->dev, "prepared, len=%d\n", len);
 93
 94	reinit_completion(&ec_rpmsg->xfer_ack);
 95	ret = rpmsg_send(ec_rpmsg->ept, ec_dev->dout, len);
 96	if (ret) {
 97		dev_err(ec_dev->dev, "rpmsg send failed\n");
 98		return ret;
 99	}
100
101	timeout = msecs_to_jiffies(EC_MSG_TIMEOUT_MS);
102	ret = wait_for_completion_timeout(&ec_rpmsg->xfer_ack, timeout);
103	if (!ret) {
104		dev_err(ec_dev->dev, "rpmsg send timeout\n");
105		return -EIO;
106	}
107
108	/* check response error code */
109	response = (struct ec_host_response *)ec_dev->din;
110	ec_msg->result = response->result;
111
112	ret = cros_ec_check_result(ec_dev, ec_msg);
113	if (ret)
114		goto exit;
115
116	if (response->data_len > ec_msg->insize) {
117		dev_err(ec_dev->dev, "packet too long (%d bytes, expected %d)",
118			response->data_len, ec_msg->insize);
119		ret = -EMSGSIZE;
120		goto exit;
121	}
122
123	/* copy response packet payload and compute checksum */
124	memcpy(ec_msg->data, ec_dev->din + sizeof(*response),
125	       response->data_len);
126
127	sum = 0;
128	for (i = 0; i < sizeof(*response) + response->data_len; i++)
129		sum += ec_dev->din[i];
130
131	if (sum) {
132		dev_err(ec_dev->dev, "bad packet checksum, calculated %x\n",
133			sum);
134		ret = -EBADMSG;
135		goto exit;
136	}
137
138	ret = response->data_len;
139exit:
140	if (ec_msg->command == EC_CMD_REBOOT_EC)
141		msleep(EC_REBOOT_DELAY_MS);
142
143	return ret;
144}
145
146static void
147cros_ec_rpmsg_host_event_function(struct work_struct *host_event_work)
148{
149	struct cros_ec_rpmsg *ec_rpmsg = container_of(host_event_work,
150						      struct cros_ec_rpmsg,
151						      host_event_work);
152	struct cros_ec_device *ec_dev = dev_get_drvdata(&ec_rpmsg->rpdev->dev);
153	bool ec_has_more_events;
154
155	do {
156		ec_has_more_events = cros_ec_handle_event(ec_dev);
157	} while (ec_has_more_events);
158}
159
160static int cros_ec_rpmsg_callback(struct rpmsg_device *rpdev, void *data,
161				  int len, void *priv, u32 src)
162{
163	struct cros_ec_device *ec_dev = dev_get_drvdata(&rpdev->dev);
164	struct cros_ec_rpmsg *ec_rpmsg = ec_dev->priv;
165	struct cros_ec_rpmsg_response *resp;
166
167	if (!len) {
168		dev_warn(ec_dev->dev, "rpmsg received empty response");
169		return -EINVAL;
170	}
171
172	resp = data;
173	len -= offsetof(struct cros_ec_rpmsg_response, data);
174	if (resp->type == HOST_COMMAND_MARK) {
175		if (len > ec_dev->din_size) {
176			dev_warn(ec_dev->dev,
177				 "received length %d > din_size %d, truncating",
178				 len, ec_dev->din_size);
179			len = ec_dev->din_size;
180		}
181
182		memcpy(ec_dev->din, resp->data, len);
183		complete(&ec_rpmsg->xfer_ack);
184	} else if (resp->type == HOST_EVENT_MARK) {
185		/*
186		 * If the host event is sent before cros_ec_register is
187		 * finished, queue the host event.
188		 */
189		if (ec_rpmsg->probe_done)
190			schedule_work(&ec_rpmsg->host_event_work);
191		else
192			ec_rpmsg->has_pending_host_event = true;
193	} else {
194		dev_warn(ec_dev->dev, "rpmsg received invalid type = %d",
195			 resp->type);
196		return -EINVAL;
197	}
198
199	return 0;
200}
201
202static struct rpmsg_endpoint *
203cros_ec_rpmsg_create_ept(struct rpmsg_device *rpdev)
204{
205	struct rpmsg_channel_info chinfo = {};
206
207	strscpy(chinfo.name, rpdev->id.name, RPMSG_NAME_SIZE);
208	chinfo.src = rpdev->src;
209	chinfo.dst = RPMSG_ADDR_ANY;
210
211	return rpmsg_create_ept(rpdev, cros_ec_rpmsg_callback, NULL, chinfo);
212}
213
214static int cros_ec_rpmsg_probe(struct rpmsg_device *rpdev)
215{
216	struct device *dev = &rpdev->dev;
217	struct cros_ec_rpmsg *ec_rpmsg;
218	struct cros_ec_device *ec_dev;
219	int ret;
220
221	ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
222	if (!ec_dev)
223		return -ENOMEM;
224
225	ec_rpmsg = devm_kzalloc(dev, sizeof(*ec_rpmsg), GFP_KERNEL);
226	if (!ec_rpmsg)
227		return -ENOMEM;
228
229	ec_dev->dev = dev;
230	ec_dev->priv = ec_rpmsg;
231	ec_dev->cmd_xfer = cros_ec_cmd_xfer_rpmsg;
232	ec_dev->pkt_xfer = cros_ec_pkt_xfer_rpmsg;
233	ec_dev->phys_name = dev_name(&rpdev->dev);
234	ec_dev->din_size = sizeof(struct ec_host_response) +
235			   sizeof(struct ec_response_get_protocol_info);
236	ec_dev->dout_size = sizeof(struct ec_host_request);
237	dev_set_drvdata(dev, ec_dev);
238
239	ec_rpmsg->rpdev = rpdev;
240	init_completion(&ec_rpmsg->xfer_ack);
241	INIT_WORK(&ec_rpmsg->host_event_work,
242		  cros_ec_rpmsg_host_event_function);
243
244	ec_rpmsg->ept = cros_ec_rpmsg_create_ept(rpdev);
245	if (!ec_rpmsg->ept)
246		return -ENOMEM;
247
248	ret = cros_ec_register(ec_dev);
249	if (ret < 0) {
250		rpmsg_destroy_ept(ec_rpmsg->ept);
251		cancel_work_sync(&ec_rpmsg->host_event_work);
252		return ret;
253	}
254
255	ec_rpmsg->probe_done = true;
256
257	if (ec_rpmsg->has_pending_host_event)
258		schedule_work(&ec_rpmsg->host_event_work);
259
260	return 0;
261}
262
263static void cros_ec_rpmsg_remove(struct rpmsg_device *rpdev)
264{
265	struct cros_ec_device *ec_dev = dev_get_drvdata(&rpdev->dev);
266	struct cros_ec_rpmsg *ec_rpmsg = ec_dev->priv;
267
268	cros_ec_unregister(ec_dev);
269	rpmsg_destroy_ept(ec_rpmsg->ept);
270	cancel_work_sync(&ec_rpmsg->host_event_work);
271}
272
273#ifdef CONFIG_PM_SLEEP
274static int cros_ec_rpmsg_suspend(struct device *dev)
275{
276	struct cros_ec_device *ec_dev = dev_get_drvdata(dev);
277
278	return cros_ec_suspend(ec_dev);
279}
280
281static int cros_ec_rpmsg_resume(struct device *dev)
282{
283	struct cros_ec_device *ec_dev = dev_get_drvdata(dev);
284
285	return cros_ec_resume(ec_dev);
286}
287#endif
288
289static SIMPLE_DEV_PM_OPS(cros_ec_rpmsg_pm_ops, cros_ec_rpmsg_suspend,
290			 cros_ec_rpmsg_resume);
291
292static const struct of_device_id cros_ec_rpmsg_of_match[] = {
293	{ .compatible = "google,cros-ec-rpmsg", },
294	{ }
295};
296MODULE_DEVICE_TABLE(of, cros_ec_rpmsg_of_match);
297
298static struct rpmsg_driver cros_ec_driver_rpmsg = {
299	.drv = {
300		.name   = "cros-ec-rpmsg",
301		.of_match_table = cros_ec_rpmsg_of_match,
302		.pm	= &cros_ec_rpmsg_pm_ops,
303	},
304	.probe		= cros_ec_rpmsg_probe,
305	.remove		= cros_ec_rpmsg_remove,
306};
307
308module_rpmsg_driver(cros_ec_driver_rpmsg);
309
310MODULE_LICENSE("GPL v2");
311MODULE_DESCRIPTION("ChromeOS EC multi function device (rpmsg)");