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/miscdevice.h>
17#include <linux/module.h>
18#include <linux/notifier.h>
19#include <linux/platform_data/cros_ec_chardev.h>
20#include <linux/platform_data/cros_ec_commands.h>
21#include <linux/platform_data/cros_ec_proto.h>
22#include <linux/platform_device.h>
23#include <linux/poll.h>
24#include <linux/slab.h>
25#include <linux/types.h>
26#include <linux/uaccess.h>
27
28#define DRV_NAME		"cros-ec-chardev"
29
30/* Arbitrary bounded size for the event queue */
31#define CROS_MAX_EVENT_LEN	PAGE_SIZE
32
33struct chardev_data {
34	struct cros_ec_dev *ec_dev;
35	struct miscdevice misc;
36};
37
38struct chardev_priv {
39	struct cros_ec_dev *ec_dev;
40	struct notifier_block notifier;
41	wait_queue_head_t wait_event;
42	unsigned long event_mask;
43	struct list_head events;
44	size_t event_len;
45};
46
47struct ec_event {
48	struct list_head node;
49	size_t size;
50	u8 event_type;
51	u8 data[];
52};
53
54static int ec_get_version(struct cros_ec_dev *ec, char *str, int maxlen)
55{
56	static const char * const current_image_name[] = {
57		"unknown", "read-only", "read-write", "invalid",
58	};
59	struct ec_response_get_version *resp;
60	struct cros_ec_command *msg;
61	int ret;
62
63	msg = kzalloc(sizeof(*msg) + sizeof(*resp), GFP_KERNEL);
64	if (!msg)
65		return -ENOMEM;
66
67	msg->command = EC_CMD_GET_VERSION + ec->cmd_offset;
68	msg->insize = sizeof(*resp);
69
70	ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
71	if (ret < 0) {
72		snprintf(str, maxlen,
73			 "Unknown EC version, returned error: %d\n",
74			 msg->result);
75		goto exit;
76	}
77
78	resp = (struct ec_response_get_version *)msg->data;
79	if (resp->current_image >= ARRAY_SIZE(current_image_name))
80		resp->current_image = 3; /* invalid */
81
82	snprintf(str, maxlen, "%s\n%s\n%s\n%s\n", CROS_EC_DEV_VERSION,
83		 resp->version_string_ro, resp->version_string_rw,
84		 current_image_name[resp->current_image]);
85
86	ret = 0;
87exit:
88	kfree(msg);
89	return ret;
90}
91
92static int cros_ec_chardev_mkbp_event(struct notifier_block *nb,
93				      unsigned long queued_during_suspend,
94				      void *_notify)
95{
96	struct chardev_priv *priv = container_of(nb, struct chardev_priv,
97						 notifier);
98	struct cros_ec_device *ec_dev = priv->ec_dev->ec_dev;
99	struct ec_event *event;
100	unsigned long event_bit = 1 << ec_dev->event_data.event_type;
101	int total_size = sizeof(*event) + ec_dev->event_size;
102
103	if (!(event_bit & priv->event_mask) ||
104	    (priv->event_len + total_size) > CROS_MAX_EVENT_LEN)
105		return NOTIFY_DONE;
106
107	event = kzalloc(total_size, GFP_KERNEL);
108	if (!event)
109		return NOTIFY_DONE;
110
111	event->size = ec_dev->event_size;
112	event->event_type = ec_dev->event_data.event_type;
113	memcpy(event->data, &ec_dev->event_data.data, ec_dev->event_size);
114
115	spin_lock(&priv->wait_event.lock);
116	list_add_tail(&event->node, &priv->events);
117	priv->event_len += total_size;
118	wake_up_locked(&priv->wait_event);
119	spin_unlock(&priv->wait_event.lock);
120
121	return NOTIFY_OK;
122}
123
124static struct ec_event *cros_ec_chardev_fetch_event(struct chardev_priv *priv,
125						    bool fetch, bool block)
126{
127	struct ec_event *event;
128	int err;
129
130	spin_lock(&priv->wait_event.lock);
131	if (!block && list_empty(&priv->events)) {
132		event = ERR_PTR(-EWOULDBLOCK);
133		goto out;
134	}
135
136	if (!fetch) {
137		event = NULL;
138		goto out;
139	}
140
141	err = wait_event_interruptible_locked(priv->wait_event,
142					      !list_empty(&priv->events));
143	if (err) {
144		event = ERR_PTR(err);
145		goto out;
146	}
147
148	event = list_first_entry(&priv->events, struct ec_event, node);
149	list_del(&event->node);
150	priv->event_len -= sizeof(*event) + event->size;
151
152out:
153	spin_unlock(&priv->wait_event.lock);
154	return event;
155}
156
157/*
158 * Device file ops
159 */
160static int cros_ec_chardev_open(struct inode *inode, struct file *filp)
161{
162	struct miscdevice *mdev = filp->private_data;
163	struct cros_ec_dev *ec_dev = dev_get_drvdata(mdev->parent);
164	struct chardev_priv *priv;
165	int ret;
166
167	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
168	if (!priv)
169		return -ENOMEM;
170
171	priv->ec_dev = ec_dev;
172	filp->private_data = priv;
173	INIT_LIST_HEAD(&priv->events);
174	init_waitqueue_head(&priv->wait_event);
175	nonseekable_open(inode, filp);
176
177	priv->notifier.notifier_call = cros_ec_chardev_mkbp_event;
178	ret = blocking_notifier_chain_register(&ec_dev->ec_dev->event_notifier,
179					       &priv->notifier);
180	if (ret) {
181		dev_err(ec_dev->dev, "failed to register event notifier\n");
182		kfree(priv);
183	}
184
185	return ret;
186}
187
188static __poll_t cros_ec_chardev_poll(struct file *filp, poll_table *wait)
189{
190	struct chardev_priv *priv = filp->private_data;
191
192	poll_wait(filp, &priv->wait_event, wait);
193
194	if (list_empty(&priv->events))
195		return 0;
196
197	return EPOLLIN | EPOLLRDNORM;
198}
199
200static ssize_t cros_ec_chardev_read(struct file *filp, char __user *buffer,
201				     size_t length, loff_t *offset)
202{
203	char msg[sizeof(struct ec_response_get_version) +
204		 sizeof(CROS_EC_DEV_VERSION)];
205	struct chardev_priv *priv = filp->private_data;
206	struct cros_ec_dev *ec_dev = priv->ec_dev;
207	size_t count;
208	int ret;
209
210	if (priv->event_mask) { /* queued MKBP event */
211		struct ec_event *event;
212
213		event = cros_ec_chardev_fetch_event(priv, length != 0,
214						!(filp->f_flags & O_NONBLOCK));
215		if (IS_ERR(event))
216			return PTR_ERR(event);
217		/*
218		 * length == 0 is special - no IO is done but we check
219		 * for error conditions.
220		 */
221		if (length == 0)
222			return 0;
223
224		/* The event is 1 byte of type plus the payload */
225		count = min(length, event->size + 1);
226		ret = copy_to_user(buffer, &event->event_type, count);
227		kfree(event);
228		if (ret) /* the copy failed */
229			return -EFAULT;
230		*offset = count;
231		return count;
232	}
233
234	/*
235	 * Legacy behavior if no event mask is defined
236	 */
237	if (*offset != 0)
238		return 0;
239
240	ret = ec_get_version(ec_dev, msg, sizeof(msg));
241	if (ret)
242		return ret;
243
244	count = min(length, strlen(msg));
245
246	if (copy_to_user(buffer, msg, count))
247		return -EFAULT;
248
249	*offset = count;
250	return count;
251}
252
253static int cros_ec_chardev_release(struct inode *inode, struct file *filp)
254{
255	struct chardev_priv *priv = filp->private_data;
256	struct cros_ec_dev *ec_dev = priv->ec_dev;
257	struct ec_event *event, *e;
258
259	blocking_notifier_chain_unregister(&ec_dev->ec_dev->event_notifier,
260					   &priv->notifier);
261
262	list_for_each_entry_safe(event, e, &priv->events, node) {
263		list_del(&event->node);
264		kfree(event);
265	}
266	kfree(priv);
267
268	return 0;
269}
270
271/*
272 * Ioctls
273 */
274static long cros_ec_chardev_ioctl_xcmd(struct cros_ec_dev *ec, void __user *arg)
275{
276	struct cros_ec_command *s_cmd;
277	struct cros_ec_command u_cmd;
278	long ret;
279
280	if (copy_from_user(&u_cmd, arg, sizeof(u_cmd)))
281		return -EFAULT;
282
283	if (u_cmd.outsize > EC_MAX_MSG_BYTES ||
284	    u_cmd.insize > EC_MAX_MSG_BYTES)
285		return -EINVAL;
286
287	s_cmd = kzalloc(sizeof(*s_cmd) + max(u_cmd.outsize, u_cmd.insize),
288			GFP_KERNEL);
289	if (!s_cmd)
290		return -ENOMEM;
291
292	if (copy_from_user(s_cmd, arg, sizeof(*s_cmd) + u_cmd.outsize)) {
293		ret = -EFAULT;
294		goto exit;
295	}
296
297	if (u_cmd.outsize != s_cmd->outsize ||
298	    u_cmd.insize != s_cmd->insize) {
299		ret = -EINVAL;
300		goto exit;
301	}
302
303	s_cmd->command += ec->cmd_offset;
304	ret = cros_ec_cmd_xfer(ec->ec_dev, s_cmd);
305	/* Only copy data to userland if data was received. */
306	if (ret < 0)
307		goto exit;
308
309	if (copy_to_user(arg, s_cmd, sizeof(*s_cmd) + s_cmd->insize))
310		ret = -EFAULT;
311exit:
312	kfree(s_cmd);
313	return ret;
314}
315
316static long cros_ec_chardev_ioctl_readmem(struct cros_ec_dev *ec,
317					   void __user *arg)
318{
319	struct cros_ec_device *ec_dev = ec->ec_dev;
320	struct cros_ec_readmem s_mem = { };
321	long num;
322
323	/* Not every platform supports direct reads */
324	if (!ec_dev->cmd_readmem)
325		return -ENOTTY;
326
327	if (copy_from_user(&s_mem, arg, sizeof(s_mem)))
328		return -EFAULT;
329
330	if (s_mem.bytes > sizeof(s_mem.buffer))
331		return -EINVAL;
332
333	num = ec_dev->cmd_readmem(ec_dev, s_mem.offset, s_mem.bytes,
334				  s_mem.buffer);
335	if (num <= 0)
336		return num;
337
338	if (copy_to_user((void __user *)arg, &s_mem, sizeof(s_mem)))
339		return -EFAULT;
340
341	return num;
342}
343
344static long cros_ec_chardev_ioctl(struct file *filp, unsigned int cmd,
345				   unsigned long arg)
346{
347	struct chardev_priv *priv = filp->private_data;
348	struct cros_ec_dev *ec = priv->ec_dev;
349
350	if (_IOC_TYPE(cmd) != CROS_EC_DEV_IOC)
351		return -ENOTTY;
352
353	switch (cmd) {
354	case CROS_EC_DEV_IOCXCMD:
355		return cros_ec_chardev_ioctl_xcmd(ec, (void __user *)arg);
356	case CROS_EC_DEV_IOCRDMEM:
357		return cros_ec_chardev_ioctl_readmem(ec, (void __user *)arg);
358	case CROS_EC_DEV_IOCEVENTMASK:
359		priv->event_mask = arg;
360		return 0;
361	}
362
363	return -ENOTTY;
364}
365
366static const struct file_operations chardev_fops = {
367	.open		= cros_ec_chardev_open,
368	.poll		= cros_ec_chardev_poll,
369	.read		= cros_ec_chardev_read,
370	.release	= cros_ec_chardev_release,
371	.unlocked_ioctl	= cros_ec_chardev_ioctl,
372#ifdef CONFIG_COMPAT
373	.compat_ioctl	= cros_ec_chardev_ioctl,
374#endif
375};
376
377static int cros_ec_chardev_probe(struct platform_device *pdev)
378{
379	struct cros_ec_dev *ec_dev = dev_get_drvdata(pdev->dev.parent);
380	struct cros_ec_platform *ec_platform = dev_get_platdata(ec_dev->dev);
381	struct chardev_data *data;
382
383	/* Create a char device: we want to create it anew */
384	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
385	if (!data)
386		return -ENOMEM;
387
388	data->ec_dev = ec_dev;
389	data->misc.minor = MISC_DYNAMIC_MINOR;
390	data->misc.fops = &chardev_fops;
391	data->misc.name = ec_platform->ec_name;
392	data->misc.parent = pdev->dev.parent;
393
394	dev_set_drvdata(&pdev->dev, data);
395
396	return misc_register(&data->misc);
397}
398
399static void cros_ec_chardev_remove(struct platform_device *pdev)
400{
401	struct chardev_data *data = dev_get_drvdata(&pdev->dev);
402
403	misc_deregister(&data->misc);
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_new = 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");
420