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 
17 MODULE_AUTHOR("Thomas Renninger <trenn@suse.de>");
18 MODULE_DESCRIPTION("ACPI EC sysfs access driver");
19 MODULE_LICENSE("GPL");
20 
21 static bool write_support;
22 module_param(write_support, bool, 0644);
23 MODULE_PARM_DESC(write_support, "Dangerous, reboot and removal of battery may "
24 		 "be needed.");
25 
26 #define EC_SPACE_SIZE 256
27 
28 static struct dentry *acpi_ec_debugfs_dir;
29 
acpi_ec_read_io(struct file * f,char __user * buf,size_t count,loff_t * off)30 static 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 
acpi_ec_write_io(struct file * f,const char __user * buf,size_t count,loff_t * off)64 static 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 
102 static 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 
acpi_ec_add_debugfs(struct acpi_ec * ec,unsigned int ec_device_count)110 static 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 
acpi_ec_sys_init(void)131 static 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 
acpi_ec_sys_exit(void)138 static void __exit acpi_ec_sys_exit(void)
139 {
140 	debugfs_remove_recursive(acpi_ec_debugfs_dir);
141 }
142 
143 module_init(acpi_ec_sys_init);
144 module_exit(acpi_ec_sys_exit);
145