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	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;
141exit:
142	if (ec_msg->command == EC_CMD_REBOOT_EC)
143		msleep(EC_REBOOT_DELAY_MS);
144
145	return ret;
146}
147
148static void
149cros_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
158static 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
200static struct rpmsg_endpoint *
201cros_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
212static 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
261static 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
272static 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
279static 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
287static SIMPLE_DEV_PM_OPS(cros_ec_rpmsg_pm_ops, cros_ec_rpmsg_suspend,
288			 cros_ec_rpmsg_resume);
289
290static const struct of_device_id cros_ec_rpmsg_of_match[] = {
291	{ .compatible = "google,cros-ec-rpmsg", },
292	{ }
293};
294MODULE_DEVICE_TABLE(of, cros_ec_rpmsg_of_match);
295
296static 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
306module_rpmsg_driver(cros_ec_driver_rpmsg);
307
308MODULE_LICENSE("GPL v2");
309MODULE_DESCRIPTION("ChromeOS EC multi function device (rpmsg)");