1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright (C) 1998, 1999 Frodo Looijaard <frodol@dds.nl> and
4 * Philip Edelbrock <phil@netroedge.com>
5 * Copyright (C) 2003 Greg Kroah-Hartman <greg@kroah.com>
6 * Copyright (C) 2003 IBM Corp.
7 * Copyright (C) 2004 Jean Delvare <jdelvare@suse.de>
8 */
9
10 #include <linux/kernel.h>
11 #include <linux/module.h>
12 #include <linux/device.h>
13 #include <linux/capability.h>
14 #include <linux/jiffies.h>
15 #include <linux/i2c.h>
16 #include <linux/mutex.h>
17
18 /* Addresses to scan */
19 static const unsigned short normal_i2c[] = { 0x50, 0x51, 0x52, 0x53, 0x54,
20 0x55, 0x56, 0x57, I2C_CLIENT_END };
21
22
23 /* Size of EEPROM in bytes */
24 #define EEPROM_SIZE 256
25
26 /* possible types of eeprom devices */
27 enum eeprom_nature {
28 UNKNOWN,
29 VAIO,
30 };
31
32 /* Each client has this additional data */
33 struct eeprom_data {
34 struct mutex update_lock;
35 u8 valid; /* bitfield, bit!=0 if slice is valid */
36 unsigned long last_updated[8]; /* In jiffies, 8 slices */
37 u8 data[EEPROM_SIZE]; /* Register values */
38 enum eeprom_nature nature;
39 };
40
41
eeprom_update_client(struct i2c_client * client,u8 slice)42 static void eeprom_update_client(struct i2c_client *client, u8 slice)
43 {
44 struct eeprom_data *data = i2c_get_clientdata(client);
45 int i;
46
47 mutex_lock(&data->update_lock);
48
49 if (!(data->valid & (1 << slice)) ||
50 time_after(jiffies, data->last_updated[slice] + 300 * HZ)) {
51 dev_dbg(&client->dev, "Starting eeprom update, slice %u\n", slice);
52
53 if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
54 for (i = slice << 5; i < (slice + 1) << 5; i += 32)
55 if (i2c_smbus_read_i2c_block_data(client, i,
56 32, data->data + i)
57 != 32)
58 goto exit;
59 } else {
60 for (i = slice << 5; i < (slice + 1) << 5; i += 2) {
61 int word = i2c_smbus_read_word_data(client, i);
62 if (word < 0)
63 goto exit;
64 data->data[i] = word & 0xff;
65 data->data[i + 1] = word >> 8;
66 }
67 }
68 data->last_updated[slice] = jiffies;
69 data->valid |= (1 << slice);
70 }
71 exit:
72 mutex_unlock(&data->update_lock);
73 }
74
eeprom_read(struct file * filp,struct kobject * kobj,struct bin_attribute * bin_attr,char * buf,loff_t off,size_t count)75 static ssize_t eeprom_read(struct file *filp, struct kobject *kobj,
76 struct bin_attribute *bin_attr,
77 char *buf, loff_t off, size_t count)
78 {
79 struct i2c_client *client = kobj_to_i2c_client(kobj);
80 struct eeprom_data *data = i2c_get_clientdata(client);
81 u8 slice;
82
83 /* Only refresh slices which contain requested bytes */
84 for (slice = off >> 5; slice <= (off + count - 1) >> 5; slice++)
85 eeprom_update_client(client, slice);
86
87 /* Hide Vaio private settings to regular users:
88 - BIOS passwords: bytes 0x00 to 0x0f
89 - UUID: bytes 0x10 to 0x1f
90 - Serial number: 0xc0 to 0xdf */
91 if (data->nature == VAIO && !capable(CAP_SYS_ADMIN)) {
92 int i;
93
94 for (i = 0; i < count; i++) {
95 if ((off + i <= 0x1f) ||
96 (off + i >= 0xc0 && off + i <= 0xdf))
97 buf[i] = 0;
98 else
99 buf[i] = data->data[off + i];
100 }
101 } else {
102 memcpy(buf, &data->data[off], count);
103 }
104
105 return count;
106 }
107
108 static const struct bin_attribute eeprom_attr = {
109 .attr = {
110 .name = "eeprom",
111 .mode = S_IRUGO,
112 },
113 .size = EEPROM_SIZE,
114 .read = eeprom_read,
115 };
116
117 /* Return 0 if detection is successful, -ENODEV otherwise */
eeprom_detect(struct i2c_client * client,struct i2c_board_info * info)118 static int eeprom_detect(struct i2c_client *client, struct i2c_board_info *info)
119 {
120 struct i2c_adapter *adapter = client->adapter;
121
122 /* EDID EEPROMs are often 24C00 EEPROMs, which answer to all
123 addresses 0x50-0x57, but we only care about 0x50. So decline
124 attaching to addresses >= 0x51 on DDC buses */
125 if (!(adapter->class & I2C_CLASS_SPD) && client->addr >= 0x51)
126 return -ENODEV;
127
128 /* There are four ways we can read the EEPROM data:
129 (1) I2C block reads (faster, but unsupported by most adapters)
130 (2) Word reads (128% overhead)
131 (3) Consecutive byte reads (88% overhead, unsafe)
132 (4) Regular byte data reads (265% overhead)
133 The third and fourth methods are not implemented by this driver
134 because all known adapters support one of the first two. */
135 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_WORD_DATA)
136 && !i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK))
137 return -ENODEV;
138
139 strscpy(info->type, "eeprom", I2C_NAME_SIZE);
140
141 return 0;
142 }
143
eeprom_probe(struct i2c_client * client)144 static int eeprom_probe(struct i2c_client *client)
145 {
146 struct i2c_adapter *adapter = client->adapter;
147 struct eeprom_data *data;
148
149 data = devm_kzalloc(&client->dev, sizeof(struct eeprom_data),
150 GFP_KERNEL);
151 if (!data)
152 return -ENOMEM;
153
154 memset(data->data, 0xff, EEPROM_SIZE);
155 i2c_set_clientdata(client, data);
156 mutex_init(&data->update_lock);
157 data->nature = UNKNOWN;
158
159 /* Detect the Vaio nature of EEPROMs.
160 We use the "PCG-" or "VGN-" prefix as the signature. */
161 if (client->addr == 0x57
162 && i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_BYTE_DATA)) {
163 char name[4];
164
165 name[0] = i2c_smbus_read_byte_data(client, 0x80);
166 name[1] = i2c_smbus_read_byte_data(client, 0x81);
167 name[2] = i2c_smbus_read_byte_data(client, 0x82);
168 name[3] = i2c_smbus_read_byte_data(client, 0x83);
169
170 if (!memcmp(name, "PCG-", 4) || !memcmp(name, "VGN-", 4)) {
171 dev_info(&client->dev, "Vaio EEPROM detected, "
172 "enabling privacy protection\n");
173 data->nature = VAIO;
174 }
175 }
176
177 /* Let the users know they are using deprecated driver */
178 dev_notice(&client->dev,
179 "eeprom driver is deprecated, please use at24 instead\n");
180
181 /* create the sysfs eeprom file */
182 return sysfs_create_bin_file(&client->dev.kobj, &eeprom_attr);
183 }
184
eeprom_remove(struct i2c_client * client)185 static void eeprom_remove(struct i2c_client *client)
186 {
187 sysfs_remove_bin_file(&client->dev.kobj, &eeprom_attr);
188 }
189
190 static const struct i2c_device_id eeprom_id[] = {
191 { "eeprom", 0 },
192 { }
193 };
194
195 static struct i2c_driver eeprom_driver = {
196 .driver = {
197 .name = "eeprom",
198 },
199 .probe = eeprom_probe,
200 .remove = eeprom_remove,
201 .id_table = eeprom_id,
202
203 .class = I2C_CLASS_DDC | I2C_CLASS_SPD,
204 .detect = eeprom_detect,
205 .address_list = normal_i2c,
206 };
207
208 module_i2c_driver(eeprom_driver);
209
210 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and "
211 "Philip Edelbrock <phil@netroedge.com> and "
212 "Greg Kroah-Hartman <greg@kroah.com>");
213 MODULE_DESCRIPTION("I2C EEPROM driver");
214 MODULE_LICENSE("GPL");
215