cros_ec_ucsi.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * UCSI driver for ChromeOS EC
  4 *
  5 * Copyright 2024 Google LLC.
  6 */
  7
  8#include <linux/container_of.h>
  9#include <linux/dev_printk.h>
 10#include <linux/jiffies.h>
 11#include <linux/mod_devicetable.h>
 12#include <linux/module.h>
 13#include <linux/platform_data/cros_ec_commands.h>
 14#include <linux/platform_data/cros_usbpd_notify.h>
 15#include <linux/platform_data/cros_ec_proto.h>
 16#include <linux/platform_device.h>
 17#include <linux/slab.h>
 18#include <linux/wait.h>
 19
 20#include "ucsi.h"
 21
 22/*
 23 * Maximum size in bytes of a UCSI message between AP and EC
 24 */
 25#define MAX_EC_DATA_SIZE	256
 26
 27/*
 28 * Maximum time in milliseconds the cros_ec_ucsi driver
 29 * will wait for a response to a command or and ack.
 30 */
 31#define WRITE_TMO_MS		5000
 32
 33/* Number of times to attempt recovery from a write timeout before giving up. */
 34#define WRITE_TMO_CTR_MAX	5
 35
 36struct cros_ucsi_data {
 37	struct device *dev;
 38	struct ucsi *ucsi;
 39
 40	struct cros_ec_device *ec;
 41	struct notifier_block nb;
 42	struct work_struct work;
 43	struct delayed_work write_tmo;
 44	int tmo_counter;
 45
 46	struct completion complete;
 47	unsigned long flags;
 48};
 49
 50static int cros_ucsi_read(struct ucsi *ucsi, unsigned int offset, void *val,
 51			  size_t val_len)
 52{
 53	struct cros_ucsi_data *udata = ucsi_get_drvdata(ucsi);
 54	struct ec_params_ucsi_ppm_get req = {
 55		.offset = offset,
 56		.size = val_len,
 57	};
 58	int ret;
 59
 60	if (val_len > MAX_EC_DATA_SIZE) {
 61		dev_err(udata->dev, "Can't read %zu bytes. Too big.\n", val_len);
 62		return -EINVAL;
 63	}
 64
 65	ret = cros_ec_cmd(udata->ec, 0, EC_CMD_UCSI_PPM_GET,
 66			  &req, sizeof(req), val, val_len);
 67	if (ret < 0) {
 68		dev_warn(udata->dev, "Failed to send EC message UCSI_PPM_GET: error=%d\n", ret);
 69		return ret;
 70	}
 71	return 0;
 72}
 73
 74static int cros_ucsi_read_version(struct ucsi *ucsi, u16 *version)
 75{
 76	return cros_ucsi_read(ucsi, UCSI_VERSION, version, sizeof(*version));
 77}
 78
 79static int cros_ucsi_read_cci(struct ucsi *ucsi, u32 *cci)
 80{
 81	return cros_ucsi_read(ucsi, UCSI_CCI, cci, sizeof(*cci));
 82}
 83
 84static int cros_ucsi_read_message_in(struct ucsi *ucsi, void *val,
 85				     size_t val_len)
 86{
 87	return cros_ucsi_read(ucsi, UCSI_MESSAGE_IN, val, val_len);
 88}
 89
 90static int cros_ucsi_async_control(struct ucsi *ucsi, u64 cmd)
 91{
 92	struct cros_ucsi_data *udata = ucsi_get_drvdata(ucsi);
 93	u8 ec_buf[sizeof(struct ec_params_ucsi_ppm_set) + sizeof(cmd)];
 94	struct ec_params_ucsi_ppm_set *req = (struct ec_params_ucsi_ppm_set *) ec_buf;
 95	int ret;
 96
 97	req->offset = UCSI_CONTROL;
 98	memcpy(req->data, &cmd, sizeof(cmd));
 99	ret = cros_ec_cmd(udata->ec, 0, EC_CMD_UCSI_PPM_SET,
100			  req, sizeof(ec_buf), NULL, 0);
101	if (ret < 0) {
102		dev_warn(udata->dev, "Failed to send EC message UCSI_PPM_SET: error=%d\n", ret);
103		return ret;
104	}
105	return 0;
106}
107
108static int cros_ucsi_sync_control(struct ucsi *ucsi, u64 cmd, u32 *cci,
109				  void *data, size_t size)
110{
111	struct cros_ucsi_data *udata = ucsi_get_drvdata(ucsi);
112	int ret;
113
114	ret = ucsi_sync_control_common(ucsi, cmd, cci, data, size);
115	switch (ret) {
116	case -EBUSY:
117		/* EC may return -EBUSY if CCI.busy is set.
118		 * Convert this to a timeout.
119		 */
120	case -ETIMEDOUT:
121		/* Schedule recovery attempt when we timeout
122		 * or tried to send a command while still busy.
123		 */
124		cancel_delayed_work_sync(&udata->write_tmo);
125		schedule_delayed_work(&udata->write_tmo,
126				      msecs_to_jiffies(WRITE_TMO_MS));
127		break;
128	case 0:
129		/* Successful write. Cancel any pending recovery work. */
130		cancel_delayed_work_sync(&udata->write_tmo);
131		break;
132	}
133
134	return ret;
135}
136
137static const struct ucsi_operations cros_ucsi_ops = {
138	.read_version = cros_ucsi_read_version,
139	.read_cci = cros_ucsi_read_cci,
140	.poll_cci = cros_ucsi_read_cci,
141	.read_message_in = cros_ucsi_read_message_in,
142	.async_control = cros_ucsi_async_control,
143	.sync_control = cros_ucsi_sync_control,
144};
145
146static void cros_ucsi_work(struct work_struct *work)
147{
148	struct cros_ucsi_data *udata = container_of(work, struct cros_ucsi_data, work);
149	u32 cci;
150
151	if (cros_ucsi_read_cci(udata->ucsi, &cci))
152		return;
153
154	ucsi_notify_common(udata->ucsi, cci);
155}
156
157static void cros_ucsi_write_timeout(struct work_struct *work)
158{
159	struct cros_ucsi_data *udata =
160		container_of(work, struct cros_ucsi_data, write_tmo.work);
161	u32 cci;
162	u64 cmd;
163
164	if (cros_ucsi_read(udata->ucsi, UCSI_CCI, &cci, sizeof(cci))) {
165		dev_err(udata->dev,
166			"Reading CCI failed; no write timeout recovery possible.\n");
167		return;
168	}
169
170	if (cci & UCSI_CCI_BUSY) {
171		udata->tmo_counter++;
172
173		if (udata->tmo_counter <= WRITE_TMO_CTR_MAX)
174			schedule_delayed_work(&udata->write_tmo,
175					      msecs_to_jiffies(WRITE_TMO_MS));
176		else
177			dev_err(udata->dev,
178				"PPM unresponsive - too many write timeouts.\n");
179
180		return;
181	}
182
183	/* No longer busy means we can reset our timeout counter. */
184	udata->tmo_counter = 0;
185
186	/* Need to ack previous command which may have timed out. */
187	if (cci & UCSI_CCI_COMMAND_COMPLETE) {
188		cmd = UCSI_ACK_CC_CI | UCSI_ACK_COMMAND_COMPLETE;
189		cros_ucsi_async_control(udata->ucsi, cmd);
190
191		/* Check again after a few seconds that the system has
192		 * recovered to make sure our async write above was successful.
193		 */
194		schedule_delayed_work(&udata->write_tmo,
195				      msecs_to_jiffies(WRITE_TMO_MS));
196		return;
197	}
198
199	/* We recovered from a previous timeout. Treat this as a recovery from
200	 * suspend and call resume.
201	 */
202	ucsi_resume(udata->ucsi);
203}
204
205static int cros_ucsi_event(struct notifier_block *nb,
206			   unsigned long host_event, void *_notify)
207{
208	struct cros_ucsi_data *udata = container_of(nb, struct cros_ucsi_data, nb);
209
210	if (host_event & PD_EVENT_INIT) {
211		/* Late init event received from ChromeOS EC. Treat this as a
212		 * system resume to re-enable communication with the PPM.
213		 */
214		dev_dbg(udata->dev, "Late PD init received\n");
215		ucsi_resume(udata->ucsi);
216	}
217
218	if (host_event & PD_EVENT_PPM) {
219		dev_dbg(udata->dev, "UCSI notification received\n");
220		flush_work(&udata->work);
221		schedule_work(&udata->work);
222	}
223
224	return NOTIFY_OK;
225}
226
227static void cros_ucsi_destroy(struct cros_ucsi_data *udata)
228{
229	cros_usbpd_unregister_notify(&udata->nb);
230	cancel_delayed_work_sync(&udata->write_tmo);
231	cancel_work_sync(&udata->work);
232	ucsi_destroy(udata->ucsi);
233}
234
235static int cros_ucsi_probe(struct platform_device *pdev)
236{
237	struct device *dev = &pdev->dev;
238	struct cros_ec_dev *ec_data = dev_get_drvdata(dev->parent);
239	struct cros_ucsi_data *udata;
240	int ret;
241
242	udata = devm_kzalloc(dev, sizeof(*udata), GFP_KERNEL);
243	if (!udata)
244		return -ENOMEM;
245
246	udata->dev = dev;
247
248	udata->ec = ec_data->ec_dev;
249	if (!udata->ec)
250		return dev_err_probe(dev, -ENODEV, "couldn't find parent EC device\n");
251
252	platform_set_drvdata(pdev, udata);
253
254	INIT_WORK(&udata->work, cros_ucsi_work);
255	INIT_DELAYED_WORK(&udata->write_tmo, cros_ucsi_write_timeout);
256	init_completion(&udata->complete);
257
258	udata->ucsi = ucsi_create(dev, &cros_ucsi_ops);
259	if (IS_ERR(udata->ucsi))
260		return dev_err_probe(dev, PTR_ERR(udata->ucsi), "failed to allocate UCSI instance\n");
261
262	ucsi_set_drvdata(udata->ucsi, udata);
263
264	udata->nb.notifier_call = cros_ucsi_event;
265	ret = cros_usbpd_register_notify(&udata->nb);
266	if (ret) {
267		dev_err_probe(dev, ret, "failed to register notifier\n");
268		ucsi_destroy(udata->ucsi);
269		return ret;
270	}
271
272	ret = ucsi_register(udata->ucsi);
273	if (ret) {
274		dev_err_probe(dev, ret, "failed to register UCSI\n");
275		cros_ucsi_destroy(udata);
276		return ret;
277	}
278
279	return 0;
280}
281
282static void cros_ucsi_remove(struct platform_device *dev)
283{
284	struct cros_ucsi_data *udata = platform_get_drvdata(dev);
285
286	ucsi_unregister(udata->ucsi);
287	cros_ucsi_destroy(udata);
288}
289
290static int __maybe_unused cros_ucsi_suspend(struct device *dev)
291{
292	struct cros_ucsi_data *udata = dev_get_drvdata(dev);
293
294	cancel_delayed_work_sync(&udata->write_tmo);
295	cancel_work_sync(&udata->work);
296
297	return 0;
298}
299
300static void __maybe_unused cros_ucsi_complete(struct device *dev)
301{
302	struct cros_ucsi_data *udata = dev_get_drvdata(dev);
303
304	ucsi_resume(udata->ucsi);
305}
306
307/*
308 * UCSI protocol is also used on ChromeOS platforms which reply on
309 * cros_ec_lpc.c driver for communication with embedded controller (EC).
310 * On such platforms communication with the EC is not available until
311 * the .complete() callback of the cros_ec_lpc driver is executed.
312 * For this reason we delay ucsi_resume() until the .complete() stage
313 * otherwise UCSI SET_NOTIFICATION_ENABLE command will fail and we won't
314 * receive any UCSI notifications from the EC where PPM is implemented.
315 */
316static const struct dev_pm_ops cros_ucsi_pm_ops = {
317#ifdef CONFIG_PM_SLEEP
318	.suspend = cros_ucsi_suspend,
319	.complete = cros_ucsi_complete,
320#endif
321};
322
323static const struct platform_device_id cros_ucsi_id[] = {
324	{ KBUILD_MODNAME, 0 },
325	{}
326};
327MODULE_DEVICE_TABLE(platform, cros_ucsi_id);
328
329static struct platform_driver cros_ucsi_driver = {
330	.driver = {
331		.name = KBUILD_MODNAME,
332		.pm = &cros_ucsi_pm_ops,
333	},
334	.id_table = cros_ucsi_id,
335	.probe = cros_ucsi_probe,
336	.remove = cros_ucsi_remove,
337};
338
339module_platform_driver(cros_ucsi_driver);
340
341MODULE_LICENSE("GPL");
342MODULE_DESCRIPTION("UCSI driver for ChromeOS EC");