1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Miscellaneous character driver for ChromeOS Embedded Controller
  4 *
  5 * Copyright 2014 Google, Inc.
  6 * Copyright 2019 Google LLC
  7 *
  8 * This file is a rework and part of the code is ported from
  9 * drivers/mfd/cros_ec_dev.c that was originally written by
 10 * Bill Richardson.
 11 */
 12
 13#include <linux/init.h>
 14#include <linux/device.h>
 15#include <linux/fs.h>
 16#include <linux/mfd/cros_ec.h>
 17#include <linux/miscdevice.h>
 18#include <linux/module.h>
 19#include <linux/notifier.h>
 20#include <linux/platform_data/cros_ec_chardev.h>
 21#include <linux/platform_data/cros_ec_commands.h>
 22#include <linux/platform_data/cros_ec_proto.h>
 23#include <linux/platform_device.h>
 24#include <linux/poll.h>
 25#include <linux/slab.h>
 26#include <linux/types.h>
 27#include <linux/uaccess.h>
 28
 29#define DRV_NAME		"cros-ec-chardev"
 30
 31/* Arbitrary bounded size for the event queue */
 32#define CROS_MAX_EVENT_LEN	PAGE_SIZE
 33
 34struct chardev_data {
 35	struct cros_ec_dev *ec_dev;
 36	struct miscdevice misc;
 37};
 38
 39struct chardev_priv {
 40	struct cros_ec_dev *ec_dev;
 41	struct notifier_block notifier;
 42	wait_queue_head_t wait_event;
 43	unsigned long event_mask;
 44	struct list_head events;
 45	size_t event_len;
 46};
 47
 48struct ec_event {
 49	struct list_head node;
 50	size_t size;
 51	u8 event_type;
 52	u8 data[0];
 53};
 54
 55static int ec_get_version(struct cros_ec_dev *ec, char *str, int maxlen)
 56{
 57	static const char * const current_image_name[] = {
 58		"unknown", "read-only", "read-write", "invalid",
 59	};
 60	struct ec_response_get_version *resp;
 61	struct cros_ec_command *msg;
 62	int ret;
 63
 64	msg = kzalloc(sizeof(*msg) + sizeof(*resp), GFP_KERNEL);
 65	if (!msg)
 66		return -ENOMEM;
 67
 68	msg->command = EC_CMD_GET_VERSION + ec->cmd_offset;
 69	msg->insize = sizeof(*resp);
 70
 71	ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
 72	if (ret < 0) {
 73		snprintf(str, maxlen,
 74			 "Unknown EC version, returned error: %d\n",
 75			 msg->result);
 76		goto exit;
 77	}
 78
 79	resp = (struct ec_response_get_version *)msg->data;
 80	if (resp->current_image >= ARRAY_SIZE(current_image_name))
 81		resp->current_image = 3; /* invalid */
 82
 83	snprintf(str, maxlen, "%s\n%s\n%s\n%s\n", CROS_EC_DEV_VERSION,
 84		 resp->version_string_ro, resp->version_string_rw,
 85		 current_image_name[resp->current_image]);
 86
 87	ret = 0;
 88exit:
 89	kfree(msg);
 90	return ret;
 91}
 92
 93static int cros_ec_chardev_mkbp_event(struct notifier_block *nb,
 94				      unsigned long queued_during_suspend,
 95				      void *_notify)
 96{
 97	struct chardev_priv *priv = container_of(nb, struct chardev_priv,
 98						 notifier);
 99	struct cros_ec_device *ec_dev = priv->ec_dev->ec_dev;
100	struct ec_event *event;
101	unsigned long event_bit = 1 << ec_dev->event_data.event_type;
102	int total_size = sizeof(*event) + ec_dev->event_size;
103
104	if (!(event_bit & priv->event_mask) ||
105	    (priv->event_len + total_size) > CROS_MAX_EVENT_LEN)
106		return NOTIFY_DONE;
107
108	event = kzalloc(total_size, GFP_KERNEL);
109	if (!event)
110		return NOTIFY_DONE;
111
112	event->size = ec_dev->event_size;
113	event->event_type = ec_dev->event_data.event_type;
114	memcpy(event->data, &ec_dev->event_data.data, ec_dev->event_size);
115
116	spin_lock(&priv->wait_event.lock);
117	list_add_tail(&event->node, &priv->events);
118	priv->event_len += total_size;
119	wake_up_locked(&priv->wait_event);
120	spin_unlock(&priv->wait_event.lock);
121
122	return NOTIFY_OK;
123}
124
125static struct ec_event *cros_ec_chardev_fetch_event(struct chardev_priv *priv,
126						    bool fetch, bool block)
127{
128	struct ec_event *event;
129	int err;
130
131	spin_lock(&priv->wait_event.lock);
132	if (!block && list_empty(&priv->events)) {
133		event = ERR_PTR(-EWOULDBLOCK);
134		goto out;
135	}
136
137	if (!fetch) {
138		event = NULL;
139		goto out;
140	}
141
142	err = wait_event_interruptible_locked(priv->wait_event,
143					      !list_empty(&priv->events));
144	if (err) {
145		event = ERR_PTR(err);
146		goto out;
147	}
148
149	event = list_first_entry(&priv->events, struct ec_event, node);
150	list_del(&event->node);
151	priv->event_len -= sizeof(*event) + event->size;
152
153out:
154	spin_unlock(&priv->wait_event.lock);
155	return event;
156}
157
158/*
159 * Device file ops
160 */
161static int cros_ec_chardev_open(struct inode *inode, struct file *filp)
162{
163	struct miscdevice *mdev = filp->private_data;
164	struct cros_ec_dev *ec_dev = dev_get_drvdata(mdev->parent);
165	struct chardev_priv *priv;
166	int ret;
167
168	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
169	if (!priv)
170		return -ENOMEM;
171
172	priv->ec_dev = ec_dev;
173	filp->private_data = priv;
174	INIT_LIST_HEAD(&priv->events);
175	init_waitqueue_head(&priv->wait_event);
176	nonseekable_open(inode, filp);
177
178	priv->notifier.notifier_call = cros_ec_chardev_mkbp_event;
179	ret = blocking_notifier_chain_register(&ec_dev->ec_dev->event_notifier,
180					       &priv->notifier);
181	if (ret) {
182		dev_err(ec_dev->dev, "failed to register event notifier\n");
183		kfree(priv);
184	}
185
186	return ret;
187}
188
189static __poll_t cros_ec_chardev_poll(struct file *filp, poll_table *wait)
190{
191	struct chardev_priv *priv = filp->private_data;
192
193	poll_wait(filp, &priv->wait_event, wait);
194
195	if (list_empty(&priv->events))
196		return 0;
197
198	return EPOLLIN | EPOLLRDNORM;
199}
200
201static ssize_t cros_ec_chardev_read(struct file *filp, char __user *buffer,
202				     size_t length, loff_t *offset)
203{
204	char msg[sizeof(struct ec_response_get_version) +
205		 sizeof(CROS_EC_DEV_VERSION)];
206	struct chardev_priv *priv = filp->private_data;
207	struct cros_ec_dev *ec_dev = priv->ec_dev;
208	size_t count;
209	int ret;
210
211	if (priv->event_mask) { /* queued MKBP event */
212		struct ec_event *event;
213
214		event = cros_ec_chardev_fetch_event(priv, length != 0,
215						!(filp->f_flags & O_NONBLOCK));
216		if (IS_ERR(event))
217			return PTR_ERR(event);
218		/*
219		 * length == 0 is special - no IO is done but we check
220		 * for error conditions.
221		 */
222		if (length == 0)
223			return 0;
224
225		/* The event is 1 byte of type plus the payload */
226		count = min(length, event->size + 1);
227		ret = copy_to_user(buffer, &event->event_type, count);
228		kfree(event);
229		if (ret) /* the copy failed */
230			return -EFAULT;
231		*offset = count;
232		return count;
233	}
234
235	/*
236	 * Legacy behavior if no event mask is defined
237	 */
238	if (*offset != 0)
239		return 0;
240
241	ret = ec_get_version(ec_dev, msg, sizeof(msg));
242	if (ret)
243		return ret;
244
245	count = min(length, strlen(msg));
246
247	if (copy_to_user(buffer, msg, count))
248		return -EFAULT;
249
250	*offset = count;
251	return count;
252}
253
254static int cros_ec_chardev_release(struct inode *inode, struct file *filp)
255{
256	struct chardev_priv *priv = filp->private_data;
257	struct cros_ec_dev *ec_dev = priv->ec_dev;
258	struct ec_event *event, *e;
259
260	blocking_notifier_chain_unregister(&ec_dev->ec_dev->event_notifier,
261					   &priv->notifier);
262
263	list_for_each_entry_safe(event, e, &priv->events, node) {
264		list_del(&event->node);
265		kfree(event);
266	}
267	kfree(priv);
268
269	return 0;
270}
271
272/*
273 * Ioctls
274 */
275static long cros_ec_chardev_ioctl_xcmd(struct cros_ec_dev *ec, void __user *arg)
276{
277	struct cros_ec_command *s_cmd;
278	struct cros_ec_command u_cmd;
279	long ret;
280
281	if (copy_from_user(&u_cmd, arg, sizeof(u_cmd)))
282		return -EFAULT;
283
284	if (u_cmd.outsize > EC_MAX_MSG_BYTES ||
285	    u_cmd.insize > EC_MAX_MSG_BYTES)
286		return -EINVAL;
287
288	s_cmd = kmalloc(sizeof(*s_cmd) + max(u_cmd.outsize, u_cmd.insize),
289			GFP_KERNEL);
290	if (!s_cmd)
291		return -ENOMEM;
292
293	if (copy_from_user(s_cmd, arg, sizeof(*s_cmd) + u_cmd.outsize)) {
294		ret = -EFAULT;
295		goto exit;
296	}
297
298	if (u_cmd.outsize != s_cmd->outsize ||
299	    u_cmd.insize != s_cmd->insize) {
300		ret = -EINVAL;
301		goto exit;
302	}
303
304	s_cmd->command += ec->cmd_offset;
305	ret = cros_ec_cmd_xfer(ec->ec_dev, s_cmd);
306	/* Only copy data to userland if data was received. */
307	if (ret < 0)
308		goto exit;
309
310	if (copy_to_user(arg, s_cmd, sizeof(*s_cmd) + s_cmd->insize))
311		ret = -EFAULT;
312exit:
313	kfree(s_cmd);
314	return ret;
315}
316
317static long cros_ec_chardev_ioctl_readmem(struct cros_ec_dev *ec,
318					   void __user *arg)
319{
320	struct cros_ec_device *ec_dev = ec->ec_dev;
321	struct cros_ec_readmem s_mem = { };
322	long num;
323
324	/* Not every platform supports direct reads */
325	if (!ec_dev->cmd_readmem)
326		return -ENOTTY;
327
328	if (copy_from_user(&s_mem, arg, sizeof(s_mem)))
329		return -EFAULT;
330
331	num = ec_dev->cmd_readmem(ec_dev, s_mem.offset, s_mem.bytes,
332				  s_mem.buffer);
333	if (num <= 0)
334		return num;
335
336	if (copy_to_user((void __user *)arg, &s_mem, sizeof(s_mem)))
337		return -EFAULT;
338
339	return num;
340}
341
342static long cros_ec_chardev_ioctl(struct file *filp, unsigned int cmd,
343				   unsigned long arg)
344{
345	struct chardev_priv *priv = filp->private_data;
346	struct cros_ec_dev *ec = priv->ec_dev;
347
348	if (_IOC_TYPE(cmd) != CROS_EC_DEV_IOC)
349		return -ENOTTY;
350
351	switch (cmd) {
352	case CROS_EC_DEV_IOCXCMD:
353		return cros_ec_chardev_ioctl_xcmd(ec, (void __user *)arg);
354	case CROS_EC_DEV_IOCRDMEM:
355		return cros_ec_chardev_ioctl_readmem(ec, (void __user *)arg);
356	case CROS_EC_DEV_IOCEVENTMASK:
357		priv->event_mask = arg;
358		return 0;
359	}
360
361	return -ENOTTY;
362}
363
364static const struct file_operations chardev_fops = {
365	.open		= cros_ec_chardev_open,
366	.poll		= cros_ec_chardev_poll,
367	.read		= cros_ec_chardev_read,
368	.release	= cros_ec_chardev_release,
369	.unlocked_ioctl	= cros_ec_chardev_ioctl,
370#ifdef CONFIG_COMPAT
371	.compat_ioctl	= cros_ec_chardev_ioctl,
372#endif
373};
374
375static int cros_ec_chardev_probe(struct platform_device *pdev)
376{
377	struct cros_ec_dev *ec_dev = dev_get_drvdata(pdev->dev.parent);
378	struct cros_ec_platform *ec_platform = dev_get_platdata(ec_dev->dev);
379	struct chardev_data *data;
380
381	/* Create a char device: we want to create it anew */
382	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
383	if (!data)
384		return -ENOMEM;
385
386	data->ec_dev = ec_dev;
387	data->misc.minor = MISC_DYNAMIC_MINOR;
388	data->misc.fops = &chardev_fops;
389	data->misc.name = ec_platform->ec_name;
390	data->misc.parent = pdev->dev.parent;
391
392	dev_set_drvdata(&pdev->dev, data);
393
394	return misc_register(&data->misc);
395}
396
397static int cros_ec_chardev_remove(struct platform_device *pdev)
398{
399	struct chardev_data *data = dev_get_drvdata(&pdev->dev);
400
401	misc_deregister(&data->misc);
402
403	return 0;
404}
405
406static struct platform_driver cros_ec_chardev_driver = {
407	.driver = {
408		.name = DRV_NAME,
409	},
410	.probe = cros_ec_chardev_probe,
411	.remove = cros_ec_chardev_remove,
412};
413
414module_platform_driver(cros_ec_chardev_driver);
415
416MODULE_ALIAS("platform:" DRV_NAME);
417MODULE_AUTHOR("Enric Balletbo i Serra <enric.balletbo@collabora.com>");
418MODULE_DESCRIPTION("ChromeOS EC Miscellaneous Character Driver");
419MODULE_LICENSE("GPL");