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/uaccess.h>
24
25#include "cros_ec_dev.h"
26
27/* Device variables */
28#define CROS_MAX_DEV 128
29static struct class *cros_class;
30static int ec_major;
31
32/* Basic communication */
33static int ec_get_version(struct cros_ec_device *ec, char *str, int maxlen)
34{
35	struct ec_response_get_version *resp;
36	static const char * const current_image_name[] = {
37		"unknown", "read-only", "read-write", "invalid",
38	};
39	struct cros_ec_command msg = {
40		.version = 0,
41		.command = EC_CMD_GET_VERSION,
42		.outdata = { 0 },
43		.outsize = 0,
44		.indata = { 0 },
45		.insize = sizeof(*resp),
46	};
47	int ret;
48
49	ret = cros_ec_cmd_xfer(ec, &msg);
50	if (ret < 0)
51		return ret;
52
53	if (msg.result != EC_RES_SUCCESS) {
54		snprintf(str, maxlen,
55			 "%s\nUnknown EC version: EC returned %d\n",
56			 CROS_EC_DEV_VERSION, msg.result);
57		return 0;
58	}
59
60	resp = (struct ec_response_get_version *)msg.indata;
61	if (resp->current_image >= ARRAY_SIZE(current_image_name))
62		resp->current_image = 3; /* invalid */
63
64	snprintf(str, maxlen, "%s\n%s\n%s\n%s\n", CROS_EC_DEV_VERSION,
65		 resp->version_string_ro, resp->version_string_rw,
66		 current_image_name[resp->current_image]);
67
68	return 0;
69}
70
71/* Device file ops */
72static int ec_device_open(struct inode *inode, struct file *filp)
73{
74	filp->private_data = container_of(inode->i_cdev,
75					  struct cros_ec_device, cdev);
76	return 0;
77}
78
79static int ec_device_release(struct inode *inode, struct file *filp)
80{
81	return 0;
82}
83
84static ssize_t ec_device_read(struct file *filp, char __user *buffer,
85			      size_t length, loff_t *offset)
86{
87	struct cros_ec_device *ec = filp->private_data;
88	char msg[sizeof(struct ec_response_get_version) +
89		 sizeof(CROS_EC_DEV_VERSION)];
90	size_t count;
91	int ret;
92
93	if (*offset != 0)
94		return 0;
95
96	ret = ec_get_version(ec, msg, sizeof(msg));
97	if (ret)
98		return ret;
99
100	count = min(length, strlen(msg));
101
102	if (copy_to_user(buffer, msg, count))
103		return -EFAULT;
104
105	*offset = count;
106	return count;
107}
108
109/* Ioctls */
110static long ec_device_ioctl_xcmd(struct cros_ec_device *ec, void __user *arg)
111{
112	long ret;
113	struct cros_ec_command s_cmd = { };
114
115	if (copy_from_user(&s_cmd, arg, sizeof(s_cmd)))
116		return -EFAULT;
117
118	ret = cros_ec_cmd_xfer(ec, &s_cmd);
119	/* Only copy data to userland if data was received. */
120	if (ret < 0)
121		return ret;
122
123	if (copy_to_user(arg, &s_cmd, sizeof(s_cmd)))
124		return -EFAULT;
125
126	return 0;
127}
128
129static long ec_device_ioctl_readmem(struct cros_ec_device *ec, void __user *arg)
130{
131	struct cros_ec_readmem s_mem = { };
132	long num;
133
134	/* Not every platform supports direct reads */
135	if (!ec->cmd_readmem)
136		return -ENOTTY;
137
138	if (copy_from_user(&s_mem, arg, sizeof(s_mem)))
139		return -EFAULT;
140
141	num = ec->cmd_readmem(ec, s_mem.offset, s_mem.bytes, s_mem.buffer);
142	if (num <= 0)
143		return num;
144
145	if (copy_to_user((void __user *)arg, &s_mem, sizeof(s_mem)))
146		return -EFAULT;
147
148	return 0;
149}
150
151static long ec_device_ioctl(struct file *filp, unsigned int cmd,
152			    unsigned long arg)
153{
154	struct cros_ec_device *ec = filp->private_data;
155
156	if (_IOC_TYPE(cmd) != CROS_EC_DEV_IOC)
157		return -ENOTTY;
158
159	switch (cmd) {
160	case CROS_EC_DEV_IOCXCMD:
161		return ec_device_ioctl_xcmd(ec, (void __user *)arg);
162	case CROS_EC_DEV_IOCRDMEM:
163		return ec_device_ioctl_readmem(ec, (void __user *)arg);
164	}
165
166	return -ENOTTY;
167}
168
169/* Module initialization */
170static const struct file_operations fops = {
171	.open = ec_device_open,
172	.release = ec_device_release,
173	.read = ec_device_read,
174	.unlocked_ioctl = ec_device_ioctl,
175};
176
177static int ec_device_probe(struct platform_device *pdev)
178{
179	struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent);
180	int retval = -ENOTTY;
181	dev_t devno = MKDEV(ec_major, 0);
182
183	/* Instantiate it (and remember the EC) */
184	cdev_init(&ec->cdev, &fops);
185
186	retval = cdev_add(&ec->cdev, devno, 1);
187	if (retval) {
188		dev_err(&pdev->dev, ": failed to add character device\n");
189		return retval;
190	}
191
192	ec->vdev = device_create(cros_class, NULL, devno, ec,
193				 CROS_EC_DEV_NAME);
194	if (IS_ERR(ec->vdev)) {
195		retval = PTR_ERR(ec->vdev);
196		dev_err(&pdev->dev, ": failed to create device\n");
197		cdev_del(&ec->cdev);
198		return retval;
199	}
200
201	/* Initialize extra interfaces */
202	ec_dev_sysfs_init(ec);
203	ec_dev_lightbar_init(ec);
204
205	return 0;
206}
207
208static int ec_device_remove(struct platform_device *pdev)
209{
210	struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent);
211
212	ec_dev_lightbar_remove(ec);
213	ec_dev_sysfs_remove(ec);
214	device_destroy(cros_class, MKDEV(ec_major, 0));
215	cdev_del(&ec->cdev);
216	return 0;
217}
218
219static struct platform_driver cros_ec_dev_driver = {
220	.driver = {
221		.name = "cros-ec-ctl",
222	},
223	.probe = ec_device_probe,
224	.remove = ec_device_remove,
225};
226
227static int __init cros_ec_dev_init(void)
228{
229	int ret;
230	dev_t dev = 0;
231
232	cros_class = class_create(THIS_MODULE, "chromeos");
233	if (IS_ERR(cros_class)) {
234		pr_err(CROS_EC_DEV_NAME ": failed to register device class\n");
235		return PTR_ERR(cros_class);
236	}
237
238	/* Get a range of minor numbers (starting with 0) to work with */
239	ret = alloc_chrdev_region(&dev, 0, CROS_MAX_DEV, CROS_EC_DEV_NAME);
240	if (ret < 0) {
241		pr_err(CROS_EC_DEV_NAME ": alloc_chrdev_region() failed\n");
242		goto failed_chrdevreg;
243	}
244	ec_major = MAJOR(dev);
245
246	/* Register the driver */
247	ret = platform_driver_register(&cros_ec_dev_driver);
248	if (ret < 0) {
249		pr_warn(CROS_EC_DEV_NAME ": can't register driver: %d\n", ret);
250		goto failed_devreg;
251	}
252	return 0;
253
254failed_devreg:
255	unregister_chrdev_region(MKDEV(ec_major, 0), CROS_MAX_DEV);
256failed_chrdevreg:
257	class_destroy(cros_class);
258	return ret;
259}
260
261static void __exit cros_ec_dev_exit(void)
262{
263	platform_driver_unregister(&cros_ec_dev_driver);
264	unregister_chrdev(ec_major, CROS_EC_DEV_NAME);
265	class_destroy(cros_class);
266}
267
268module_init(cros_ec_dev_init);
269module_exit(cros_ec_dev_exit);
270
271MODULE_AUTHOR("Bill Richardson <wfrichar@chromium.org>");
272MODULE_DESCRIPTION("Userspace interface to the Chrome OS Embedded Controller");
273MODULE_VERSION("1.0");
274MODULE_LICENSE("GPL");
275