xref: /kernel/linux/linux-5.10/drivers/acpi/ec_sys.c (revision 8c2ecf20) 
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * ec_sys.c
4 *
5 * Copyright (C) 2010 SUSE Products GmbH/Novell
6 * Author:
7 *      Thomas Renninger <trenn@suse.de>
8 */
9
10#include <linux/kernel.h>
11#include <linux/acpi.h>
12#include <linux/debugfs.h>
13#include <linux/module.h>
14#include <linux/uaccess.h>
15#include "internal.h"
16
17MODULE_AUTHOR("Thomas Renninger <trenn@suse.de>");
18MODULE_DESCRIPTION("ACPI EC sysfs access driver");
19MODULE_LICENSE("GPL");
20
21static bool write_support;
22module_param(write_support, bool, 0644);
23MODULE_PARM_DESC(write_support, "Dangerous, reboot and removal of battery may "
24		 "be needed.");
25
26#define EC_SPACE_SIZE 256
27
28static struct dentry *acpi_ec_debugfs_dir;
29
30static ssize_t acpi_ec_read_io(struct file *f, char __user *buf,
31			       size_t count, loff_t *off)
32{
33	/* Use this if support reading/writing multiple ECs exists in ec.c:
34	 * struct acpi_ec *ec = ((struct seq_file *)f->private_data)->private;
35	 */
36	unsigned int size = EC_SPACE_SIZE;
37	loff_t init_off = *off;
38	int err = 0;
39
40	if (*off >= size)
41		return 0;
42	if (*off + count >= size) {
43		size -= *off;
44		count = size;
45	} else
46		size = count;
47
48	while (size) {
49		u8 byte_read;
50		err = ec_read(*off, &byte_read);
51		if (err)
52			return err;
53		if (put_user(byte_read, buf + *off - init_off)) {
54			if (*off - init_off)
55				return *off - init_off; /* partial read */
56			return -EFAULT;
57		}
58		*off += 1;
59		size--;
60	}
61	return count;
62}
63
64static ssize_t acpi_ec_write_io(struct file *f, const char __user *buf,
65				size_t count, loff_t *off)
66{
67	/* Use this if support reading/writing multiple ECs exists in ec.c:
68	 * struct acpi_ec *ec = ((struct seq_file *)f->private_data)->private;
69	 */
70
71	unsigned int size = count;
72	loff_t init_off = *off;
73	int err = 0;
74
75	if (!write_support)
76		return -EINVAL;
77
78	if (*off >= EC_SPACE_SIZE)
79		return 0;
80	if (*off + count >= EC_SPACE_SIZE) {
81		size = EC_SPACE_SIZE - *off;
82		count = size;
83	}
84
85	while (size) {
86		u8 byte_write;
87		if (get_user(byte_write, buf + *off - init_off)) {
88			if (*off - init_off)
89				return *off - init_off; /* partial write */
90			return -EFAULT;
91		}
92		err = ec_write(*off, byte_write);
93		if (err)
94			return err;
95
96		*off += 1;
97		size--;
98	}
99	return count;
100}
101
102static const struct file_operations acpi_ec_io_ops = {
103	.owner = THIS_MODULE,
104	.open  = simple_open,
105	.read  = acpi_ec_read_io,
106	.write = acpi_ec_write_io,
107	.llseek = default_llseek,
108};
109
110static void acpi_ec_add_debugfs(struct acpi_ec *ec, unsigned int ec_device_count)
111{
112	struct dentry *dev_dir;
113	char name[64];
114	umode_t mode = 0400;
115
116	if (ec_device_count == 0)
117		acpi_ec_debugfs_dir = debugfs_create_dir("ec", NULL);
118
119	sprintf(name, "ec%u", ec_device_count);
120	dev_dir = debugfs_create_dir(name, acpi_ec_debugfs_dir);
121
122	debugfs_create_x32("gpe", 0444, dev_dir, &first_ec->gpe);
123	debugfs_create_bool("use_global_lock", 0444, dev_dir,
124			    &first_ec->global_lock);
125
126	if (write_support)
127		mode = 0600;
128	debugfs_create_file("io", mode, dev_dir, ec, &acpi_ec_io_ops);
129}
130
131static int __init acpi_ec_sys_init(void)
132{
133	if (first_ec)
134		acpi_ec_add_debugfs(first_ec, 0);
135	return 0;
136}
137
138static void __exit acpi_ec_sys_exit(void)
139{
140	debugfs_remove_recursive(acpi_ec_debugfs_dir);
141}
142
143module_init(acpi_ec_sys_init);
144module_exit(acpi_ec_sys_exit);
145