1/*
  2 * cros_ec_dev - expose the Chrome OS Embedded Controller to user-space
  3 *
  4 * Copyright (C) 2014 Google, Inc.
  5 *
  6 * This program is free software; you can redistribute it and/or modify
  7 * it under the terms of the GNU General Public License as published by
  8 * the Free Software Foundation; either version 2 of the License, or
  9 * (at your option) any later version.
 10 *
 11 * This program is distributed in the hope that it will be useful,
 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 14 * GNU General Public License for more details.
 15 *
 16 * You should have received a copy of the GNU General Public License
 17 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 18 */
 19
 20#include <linux/fs.h>
 21#include <linux/module.h>
 22#include <linux/platform_device.h>
 23#include <linux/slab.h>
 24#include <linux/uaccess.h>
 25
 26#include "cros_ec_dev.h"
 27
 28/* Device variables */
 29#define CROS_MAX_DEV 128
 30static int ec_major;
 31
 32static const struct attribute_group *cros_ec_groups[] = {
 33	&cros_ec_attr_group,
 34	&cros_ec_lightbar_attr_group,
 35	&cros_ec_vbc_attr_group,
 36	NULL,
 37};
 38
 39static struct class cros_class = {
 40	.owner          = THIS_MODULE,
 41	.name           = "chromeos",
 42	.dev_groups     = cros_ec_groups,
 43};
 44
 45/* Basic communication */
 46static int ec_get_version(struct cros_ec_dev *ec, char *str, int maxlen)
 47{
 48	struct ec_response_get_version *resp;
 49	static const char * const current_image_name[] = {
 50		"unknown", "read-only", "read-write", "invalid",
 51	};
 52	struct cros_ec_command *msg;
 53	int ret;
 54
 55	msg = kmalloc(sizeof(*msg) + sizeof(*resp), GFP_KERNEL);
 56	if (!msg)
 57		return -ENOMEM;
 58
 59	msg->version = 0;
 60	msg->command = EC_CMD_GET_VERSION + ec->cmd_offset;
 61	msg->insize = sizeof(*resp);
 62	msg->outsize = 0;
 63
 64	ret = cros_ec_cmd_xfer(ec->ec_dev, msg);
 65	if (ret < 0)
 66		goto exit;
 67
 68	if (msg->result != EC_RES_SUCCESS) {
 69		snprintf(str, maxlen,
 70			 "%s\nUnknown EC version: EC returned %d\n",
 71			 CROS_EC_DEV_VERSION, msg->result);
 72		ret = -EINVAL;
 73		goto exit;
 74	}
 75
 76	resp = (struct ec_response_get_version *)msg->data;
 77	if (resp->current_image >= ARRAY_SIZE(current_image_name))
 78		resp->current_image = 3; /* invalid */
 79
 80	snprintf(str, maxlen, "%s\n%s\n%s\n%s\n", CROS_EC_DEV_VERSION,
 81		 resp->version_string_ro, resp->version_string_rw,
 82		 current_image_name[resp->current_image]);
 83
 84	ret = 0;
 85exit:
 86	kfree(msg);
 87	return ret;
 88}
 89
 90/* Device file ops */
 91static int ec_device_open(struct inode *inode, struct file *filp)
 92{
 93	struct cros_ec_dev *ec = container_of(inode->i_cdev,
 94					      struct cros_ec_dev, cdev);
 95	filp->private_data = ec;
 96	nonseekable_open(inode, filp);
 97	return 0;
 98}
 99
100static int ec_device_release(struct inode *inode, struct file *filp)
101{
102	return 0;
103}
104
105static ssize_t ec_device_read(struct file *filp, char __user *buffer,
106			      size_t length, loff_t *offset)
107{
108	struct cros_ec_dev *ec = filp->private_data;
109	char msg[sizeof(struct ec_response_get_version) +
110		 sizeof(CROS_EC_DEV_VERSION)];
111	size_t count;
112	int ret;
113
114	if (*offset != 0)
115		return 0;
116
117	ret = ec_get_version(ec, msg, sizeof(msg));
118	if (ret)
119		return ret;
120
121	count = min(length, strlen(msg));
122
123	if (copy_to_user(buffer, msg, count))
124		return -EFAULT;
125
126	*offset = count;
127	return count;
128}
129
130/* Ioctls */
131static long ec_device_ioctl_xcmd(struct cros_ec_dev *ec, void __user *arg)
132{
133	long ret;
134	struct cros_ec_command u_cmd;
135	struct cros_ec_command *s_cmd;
136
137	if (copy_from_user(&u_cmd, arg, sizeof(u_cmd)))
138		return -EFAULT;
139
140	s_cmd = kmalloc(sizeof(*s_cmd) + max(u_cmd.outsize, u_cmd.insize),
141			GFP_KERNEL);
142	if (!s_cmd)
143		return -ENOMEM;
144
145	if (copy_from_user(s_cmd, arg, sizeof(*s_cmd) + u_cmd.outsize)) {
146		ret = -EFAULT;
147		goto exit;
148	}
149
150	s_cmd->command += ec->cmd_offset;
151	ret = cros_ec_cmd_xfer(ec->ec_dev, s_cmd);
152	/* Only copy data to userland if data was received. */
153	if (ret < 0)
154		goto exit;
155
156	if (copy_to_user(arg, s_cmd, sizeof(*s_cmd) + u_cmd.insize))
157		ret = -EFAULT;
158exit:
159	kfree(s_cmd);
160	return ret;
161}
162
163static long ec_device_ioctl_readmem(struct cros_ec_dev *ec, void __user *arg)
164{
165	struct cros_ec_device *ec_dev = ec->ec_dev;
166	struct cros_ec_readmem s_mem = { };
167	long num;
168
169	/* Not every platform supports direct reads */
170	if (!ec_dev->cmd_readmem)
171		return -ENOTTY;
172
173	if (copy_from_user(&s_mem, arg, sizeof(s_mem)))
174		return -EFAULT;
175
176	num = ec_dev->cmd_readmem(ec_dev, s_mem.offset, s_mem.bytes,
177				  s_mem.buffer);
178	if (num <= 0)
179		return num;
180
181	if (copy_to_user((void __user *)arg, &s_mem, sizeof(s_mem)))
182		return -EFAULT;
183
184	return 0;
185}
186
187static long ec_device_ioctl(struct file *filp, unsigned int cmd,
188			    unsigned long arg)
189{
190	struct cros_ec_dev *ec = filp->private_data;
191
192	if (_IOC_TYPE(cmd) != CROS_EC_DEV_IOC)
193		return -ENOTTY;
194
195	switch (cmd) {
196	case CROS_EC_DEV_IOCXCMD:
197		return ec_device_ioctl_xcmd(ec, (void __user *)arg);
198	case CROS_EC_DEV_IOCRDMEM:
199		return ec_device_ioctl_readmem(ec, (void __user *)arg);
200	}
201
202	return -ENOTTY;
203}
204
205/* Module initialization */
206static const struct file_operations fops = {
207	.open = ec_device_open,
208	.release = ec_device_release,
209	.read = ec_device_read,
210	.unlocked_ioctl = ec_device_ioctl,
211};
212
213static void __remove(struct device *dev)
214{
215	struct cros_ec_dev *ec = container_of(dev, struct cros_ec_dev,
216					      class_dev);
217	kfree(ec);
218}
219
220static int ec_device_probe(struct platform_device *pdev)
221{
222	int retval = -ENOMEM;
223	struct device *dev = &pdev->dev;
224	struct cros_ec_platform *ec_platform = dev_get_platdata(dev);
225	dev_t devno = MKDEV(ec_major, pdev->id);
226	struct cros_ec_dev *ec = kzalloc(sizeof(*ec), GFP_KERNEL);
227
228	if (!ec)
229		return retval;
230
231	dev_set_drvdata(dev, ec);
232	ec->ec_dev = dev_get_drvdata(dev->parent);
233	ec->dev = dev;
234	ec->cmd_offset = ec_platform->cmd_offset;
235	device_initialize(&ec->class_dev);
236	cdev_init(&ec->cdev, &fops);
237
238	/*
239	 * Add the character device
240	 * Link cdev to the class device to be sure device is not used
241	 * before unbinding it.
242	 */
243	ec->cdev.kobj.parent = &ec->class_dev.kobj;
244	retval = cdev_add(&ec->cdev, devno, 1);
245	if (retval) {
246		dev_err(dev, ": failed to add character device\n");
247		goto cdev_add_failed;
248	}
249
250	/*
251	 * Add the class device
252	 * Link to the character device for creating the /dev entry
253	 * in devtmpfs.
254	 */
255	ec->class_dev.devt = ec->cdev.dev;
256	ec->class_dev.class = &cros_class;
257	ec->class_dev.parent = dev;
258	ec->class_dev.release = __remove;
259
260	retval = dev_set_name(&ec->class_dev, "%s", ec_platform->ec_name);
261	if (retval) {
262		dev_err(dev, "dev_set_name failed => %d\n", retval);
263		goto set_named_failed;
264	}
265
266	retval = device_add(&ec->class_dev);
267	if (retval) {
268		dev_err(dev, "device_register failed => %d\n", retval);
269		goto dev_reg_failed;
270	}
271
272	return 0;
273
274dev_reg_failed:
275set_named_failed:
276	dev_set_drvdata(dev, NULL);
277	cdev_del(&ec->cdev);
278cdev_add_failed:
279	kfree(ec);
280	return retval;
281}
282
283static int ec_device_remove(struct platform_device *pdev)
284{
285	struct cros_ec_dev *ec = dev_get_drvdata(&pdev->dev);
286	cdev_del(&ec->cdev);
287	device_unregister(&ec->class_dev);
288	return 0;
289}
290
291static const struct platform_device_id cros_ec_id[] = {
292	{ "cros-ec-ctl", 0 },
293	{ /* sentinel */ },
294};
295MODULE_DEVICE_TABLE(platform, cros_ec_id);
296
297static struct platform_driver cros_ec_dev_driver = {
298	.driver = {
299		.name = "cros-ec-ctl",
300	},
301	.probe = ec_device_probe,
302	.remove = ec_device_remove,
303};
304
305static int __init cros_ec_dev_init(void)
306{
307	int ret;
308	dev_t dev = 0;
309
310	ret  = class_register(&cros_class);
311	if (ret) {
312		pr_err(CROS_EC_DEV_NAME ": failed to register device class\n");
313		return ret;
314	}
315
316	/* Get a range of minor numbers (starting with 0) to work with */
317	ret = alloc_chrdev_region(&dev, 0, CROS_MAX_DEV, CROS_EC_DEV_NAME);
318	if (ret < 0) {
319		pr_err(CROS_EC_DEV_NAME ": alloc_chrdev_region() failed\n");
320		goto failed_chrdevreg;
321	}
322	ec_major = MAJOR(dev);
323
324	/* Register the driver */
325	ret = platform_driver_register(&cros_ec_dev_driver);
326	if (ret < 0) {
327		pr_warn(CROS_EC_DEV_NAME ": can't register driver: %d\n", ret);
328		goto failed_devreg;
329	}
330	return 0;
331
332failed_devreg:
333	unregister_chrdev_region(MKDEV(ec_major, 0), CROS_MAX_DEV);
334failed_chrdevreg:
335	class_unregister(&cros_class);
336	return ret;
337}
338
339static void __exit cros_ec_dev_exit(void)
340{
341	platform_driver_unregister(&cros_ec_dev_driver);
342	unregister_chrdev(ec_major, CROS_EC_DEV_NAME);
343	class_unregister(&cros_class);
344}
345
346module_init(cros_ec_dev_init);
347module_exit(cros_ec_dev_exit);
348
349MODULE_AUTHOR("Bill Richardson <wfrichar@chromium.org>");
350MODULE_DESCRIPTION("Userspace interface to the Chrome OS Embedded Controller");
351MODULE_VERSION("1.0");
352MODULE_LICENSE("GPL");