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/mod_devicetable.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
34 struct chardev_data {
35 struct cros_ec_dev *ec_dev;
36 struct miscdevice misc;
37 };
38
39 struct 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
48 struct ec_event {
49 struct list_head node;
50 size_t size;
51 u8 event_type;
52 u8 data[];
53 };
54
ec_get_version(struct cros_ec_dev * ec,char * str,int maxlen)55 static 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;
88 exit:
89 kfree(msg);
90 return ret;
91 }
92
cros_ec_chardev_mkbp_event(struct notifier_block * nb,unsigned long queued_during_suspend,void * _notify)93 static 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
cros_ec_chardev_fetch_event(struct chardev_priv * priv,bool fetch,bool block)125 static 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
153 out:
154 spin_unlock(&priv->wait_event.lock);
155 return event;
156 }
157
158 /*
159 * Device file ops
160 */
cros_ec_chardev_open(struct inode * inode,struct file * filp)161 static 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
cros_ec_chardev_poll(struct file * filp,poll_table * wait)189 static __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
cros_ec_chardev_read(struct file * filp,char __user * buffer,size_t length,loff_t * offset)201 static 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
cros_ec_chardev_release(struct inode * inode,struct file * filp)254 static 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 */
cros_ec_chardev_ioctl_xcmd(struct cros_ec_dev * ec,void __user * arg)275 static 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 = kzalloc(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;
312 exit:
313 kfree(s_cmd);
314 return ret;
315 }
316
cros_ec_chardev_ioctl_readmem(struct cros_ec_dev * ec,void __user * arg)317 static 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 if (s_mem.bytes > sizeof(s_mem.buffer))
332 return -EINVAL;
333
334 num = ec_dev->cmd_readmem(ec_dev, s_mem.offset, s_mem.bytes,
335 s_mem.buffer);
336 if (num <= 0)
337 return num;
338
339 if (copy_to_user((void __user *)arg, &s_mem, sizeof(s_mem)))
340 return -EFAULT;
341
342 return num;
343 }
344
cros_ec_chardev_ioctl(struct file * filp,unsigned int cmd,unsigned long arg)345 static long cros_ec_chardev_ioctl(struct file *filp, unsigned int cmd,
346 unsigned long arg)
347 {
348 struct chardev_priv *priv = filp->private_data;
349 struct cros_ec_dev *ec = priv->ec_dev;
350
351 if (_IOC_TYPE(cmd) != CROS_EC_DEV_IOC)
352 return -ENOTTY;
353
354 switch (cmd) {
355 case CROS_EC_DEV_IOCXCMD:
356 return cros_ec_chardev_ioctl_xcmd(ec, (void __user *)arg);
357 case CROS_EC_DEV_IOCRDMEM:
358 return cros_ec_chardev_ioctl_readmem(ec, (void __user *)arg);
359 case CROS_EC_DEV_IOCEVENTMASK:
360 priv->event_mask = arg;
361 return 0;
362 }
363
364 return -ENOTTY;
365 }
366
367 static const struct file_operations chardev_fops = {
368 .open = cros_ec_chardev_open,
369 .poll = cros_ec_chardev_poll,
370 .read = cros_ec_chardev_read,
371 .release = cros_ec_chardev_release,
372 .unlocked_ioctl = cros_ec_chardev_ioctl,
373 #ifdef CONFIG_COMPAT
374 .compat_ioctl = cros_ec_chardev_ioctl,
375 #endif
376 };
377
cros_ec_chardev_probe(struct platform_device * pdev)378 static int cros_ec_chardev_probe(struct platform_device *pdev)
379 {
380 struct cros_ec_dev *ec_dev = dev_get_drvdata(pdev->dev.parent);
381 struct cros_ec_platform *ec_platform = dev_get_platdata(ec_dev->dev);
382 struct chardev_data *data;
383
384 /* Create a char device: we want to create it anew */
385 data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
386 if (!data)
387 return -ENOMEM;
388
389 data->ec_dev = ec_dev;
390 data->misc.minor = MISC_DYNAMIC_MINOR;
391 data->misc.fops = &chardev_fops;
392 data->misc.name = ec_platform->ec_name;
393 data->misc.parent = pdev->dev.parent;
394
395 dev_set_drvdata(&pdev->dev, data);
396
397 return misc_register(&data->misc);
398 }
399
cros_ec_chardev_remove(struct platform_device * pdev)400 static void cros_ec_chardev_remove(struct platform_device *pdev)
401 {
402 struct chardev_data *data = dev_get_drvdata(&pdev->dev);
403
404 misc_deregister(&data->misc);
405 }
406
407 static const struct platform_device_id cros_ec_chardev_id[] = {
408 { DRV_NAME, 0 },
409 {}
410 };
411 MODULE_DEVICE_TABLE(platform, cros_ec_chardev_id);
412
413 static struct platform_driver cros_ec_chardev_driver = {
414 .driver = {
415 .name = DRV_NAME,
416 },
417 .probe = cros_ec_chardev_probe,
418 .remove_new = cros_ec_chardev_remove,
419 .id_table = cros_ec_chardev_id,
420 };
421
422 module_platform_driver(cros_ec_chardev_driver);
423
424 MODULE_AUTHOR("Enric Balletbo i Serra <enric.balletbo@collabora.com>");
425 MODULE_DESCRIPTION("ChromeOS EC Miscellaneous Character Driver");
426 MODULE_LICENSE("GPL");
427