1 /*
2  * memconsole.c
3  *
4  * Architecture-independent parts of the memory based BIOS console.
5  *
6  * Copyright 2017 Google Inc.
7  *
8  * This program is free software; you can redistribute it and/or modify
9  * it under the terms of the GNU General Public License v2.0 as published by
10  * the Free Software Foundation.
11  *
12  * This program is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15  * GNU General Public License for more details.
16  */
17 
18 #include <linux/init.h>
19 #include <linux/sysfs.h>
20 #include <linux/kobject.h>
21 #include <linux/module.h>
22 
23 #include "memconsole.h"
24 
25 static ssize_t (*memconsole_read_func)(char *, loff_t, size_t);
26 
27 static ssize_t memconsole_read(struct file *filp, struct kobject *kobp,
28 			       struct bin_attribute *bin_attr, char *buf,
29 			       loff_t pos, size_t count)
30 {
31 	if (WARN_ON_ONCE(!memconsole_read_func))
32 		return -EIO;
33 	return memconsole_read_func(buf, pos, count);
34 }
35 
36 static struct bin_attribute memconsole_bin_attr = {
37 	.attr = {.name = "log", .mode = 0444},
38 	.read = memconsole_read,
39 };
40 
41 void memconsole_setup(ssize_t (*read_func)(char *, loff_t, size_t))
42 {
43 	memconsole_read_func = read_func;
44 }
45 EXPORT_SYMBOL(memconsole_setup);
46 
47 int memconsole_sysfs_init(void)
48 {
49 	return sysfs_create_bin_file(firmware_kobj, &memconsole_bin_attr);
50 }
51 EXPORT_SYMBOL(memconsole_sysfs_init);
52 
53 void memconsole_exit(void)
54 {
55 	sysfs_remove_bin_file(firmware_kobj, &memconsole_bin_attr);
56 }
57 EXPORT_SYMBOL(memconsole_exit);
58 
59 MODULE_AUTHOR("Google, Inc.");
60 MODULE_LICENSE("GPL");
61