1 /*
2 Copyright (C) 1998, 1999 Frodo Looijaard <frodol@dds.nl> and
3 Philip Edelbrock <phil@netroedge.com>
4 Copyright (C) 2003 Greg Kroah-Hartman <greg@kroah.com>
5 Copyright (C) 2003 IBM Corp.
6 Copyright (C) 2004 Jean Delvare <khali@linux-fr.org>
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 as published by
10 the Free Software Foundation; either version 2 of the License, or
11 (at your option) any later version.
12
13 This program is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
17
18 You should have received a copy of the GNU General Public License
19 along with this program; if not, write to the Free Software
20 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
21 */
22
23 #include <linux/kernel.h>
24 #include <linux/init.h>
25 #include <linux/module.h>
26 #include <linux/slab.h>
27 #include <linux/jiffies.h>
28 #include <linux/i2c.h>
29 #include <linux/mutex.h>
30
31 /* Addresses to scan */
32 static const unsigned short normal_i2c[] = { 0x50, 0x51, 0x52, 0x53, 0x54,
33 0x55, 0x56, 0x57, I2C_CLIENT_END };
34
35 /* Insmod parameters */
36 I2C_CLIENT_INSMOD_1(eeprom);
37
38
39 /* Size of EEPROM in bytes */
40 #define EEPROM_SIZE 256
41
42 /* possible types of eeprom devices */
43 enum eeprom_nature {
44 UNKNOWN,
45 VAIO,
46 };
47
48 /* Each client has this additional data */
49 struct eeprom_data {
50 struct mutex update_lock;
51 u8 valid; /* bitfield, bit!=0 if slice is valid */
52 unsigned long last_updated[8]; /* In jiffies, 8 slices */
53 u8 data[EEPROM_SIZE]; /* Register values */
54 enum eeprom_nature nature;
55 };
56
57
eeprom_update_client(struct i2c_client * client,u8 slice)58 static void eeprom_update_client(struct i2c_client *client, u8 slice)
59 {
60 struct eeprom_data *data = i2c_get_clientdata(client);
61 int i;
62
63 mutex_lock(&data->update_lock);
64
65 if (!(data->valid & (1 << slice)) ||
66 time_after(jiffies, data->last_updated[slice] + 300 * HZ)) {
67 dev_dbg(&client->dev, "Starting eeprom update, slice %u\n", slice);
68
69 if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
70 for (i = slice << 5; i < (slice + 1) << 5; i += 32)
71 if (i2c_smbus_read_i2c_block_data(client, i,
72 32, data->data + i)
73 != 32)
74 goto exit;
75 } else {
76 for (i = slice << 5; i < (slice + 1) << 5; i += 2) {
77 int word = i2c_smbus_read_word_data(client, i);
78 if (word < 0)
79 goto exit;
80 data->data[i] = word & 0xff;
81 data->data[i + 1] = word >> 8;
82 }
83 }
84 data->last_updated[slice] = jiffies;
85 data->valid |= (1 << slice);
86 }
87 exit:
88 mutex_unlock(&data->update_lock);
89 }
90
eeprom_read(struct kobject * kobj,struct bin_attribute * bin_attr,char * buf,loff_t off,size_t count)91 static ssize_t eeprom_read(struct kobject *kobj, struct bin_attribute *bin_attr,
92 char *buf, loff_t off, size_t count)
93 {
94 struct i2c_client *client = to_i2c_client(container_of(kobj, struct device, kobj));
95 struct eeprom_data *data = i2c_get_clientdata(client);
96 u8 slice;
97
98 if (off > EEPROM_SIZE)
99 return 0;
100 if (off + count > EEPROM_SIZE)
101 count = EEPROM_SIZE - off;
102
103 /* Only refresh slices which contain requested bytes */
104 for (slice = off >> 5; slice <= (off + count - 1) >> 5; slice++)
105 eeprom_update_client(client, slice);
106
107 /* Hide Vaio private settings to regular users:
108 - BIOS passwords: bytes 0x00 to 0x0f
109 - UUID: bytes 0x10 to 0x1f
110 - Serial number: 0xc0 to 0xdf */
111 if (data->nature == VAIO && !capable(CAP_SYS_ADMIN)) {
112 int i;
113
114 for (i = 0; i < count; i++) {
115 if ((off + i <= 0x1f) ||
116 (off + i >= 0xc0 && off + i <= 0xdf))
117 buf[i] = 0;
118 else
119 buf[i] = data->data[off + i];
120 }
121 } else {
122 memcpy(buf, &data->data[off], count);
123 }
124
125 return count;
126 }
127
128 static struct bin_attribute eeprom_attr = {
129 .attr = {
130 .name = "eeprom",
131 .mode = S_IRUGO,
132 },
133 .size = EEPROM_SIZE,
134 .read = eeprom_read,
135 };
136
137 /* Return 0 if detection is successful, -ENODEV otherwise */
eeprom_detect(struct i2c_client * client,int kind,struct i2c_board_info * info)138 static int eeprom_detect(struct i2c_client *client, int kind,
139 struct i2c_board_info *info)
140 {
141 struct i2c_adapter *adapter = client->adapter;
142
143 /* EDID EEPROMs are often 24C00 EEPROMs, which answer to all
144 addresses 0x50-0x57, but we only care about 0x50. So decline
145 attaching to addresses >= 0x51 on DDC buses */
146 if (!(adapter->class & I2C_CLASS_SPD) && client->addr >= 0x51)
147 return -ENODEV;
148
149 /* There are four ways we can read the EEPROM data:
150 (1) I2C block reads (faster, but unsupported by most adapters)
151 (2) Word reads (128% overhead)
152 (3) Consecutive byte reads (88% overhead, unsafe)
153 (4) Regular byte data reads (265% overhead)
154 The third and fourth methods are not implemented by this driver
155 because all known adapters support one of the first two. */
156 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_WORD_DATA)
157 && !i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK))
158 return -ENODEV;
159
160 strlcpy(info->type, "eeprom", I2C_NAME_SIZE);
161
162 return 0;
163 }
164
eeprom_probe(struct i2c_client * client,const struct i2c_device_id * id)165 static int eeprom_probe(struct i2c_client *client,
166 const struct i2c_device_id *id)
167 {
168 struct i2c_adapter *adapter = client->adapter;
169 struct eeprom_data *data;
170 int err;
171
172 if (!(data = kzalloc(sizeof(struct eeprom_data), GFP_KERNEL))) {
173 err = -ENOMEM;
174 goto exit;
175 }
176
177 memset(data->data, 0xff, EEPROM_SIZE);
178 i2c_set_clientdata(client, data);
179 mutex_init(&data->update_lock);
180 data->nature = UNKNOWN;
181
182 /* Detect the Vaio nature of EEPROMs.
183 We use the "PCG-" or "VGN-" prefix as the signature. */
184 if (client->addr == 0x57
185 && i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_BYTE_DATA)) {
186 char name[4];
187
188 name[0] = i2c_smbus_read_byte_data(client, 0x80);
189 name[1] = i2c_smbus_read_byte_data(client, 0x81);
190 name[2] = i2c_smbus_read_byte_data(client, 0x82);
191 name[3] = i2c_smbus_read_byte_data(client, 0x83);
192
193 if (!memcmp(name, "PCG-", 4) || !memcmp(name, "VGN-", 4)) {
194 dev_info(&client->dev, "Vaio EEPROM detected, "
195 "enabling privacy protection\n");
196 data->nature = VAIO;
197 }
198 }
199
200 /* create the sysfs eeprom file */
201 err = sysfs_create_bin_file(&client->dev.kobj, &eeprom_attr);
202 if (err)
203 goto exit_kfree;
204
205 return 0;
206
207 exit_kfree:
208 kfree(data);
209 exit:
210 return err;
211 }
212
eeprom_remove(struct i2c_client * client)213 static int eeprom_remove(struct i2c_client *client)
214 {
215 sysfs_remove_bin_file(&client->dev.kobj, &eeprom_attr);
216 kfree(i2c_get_clientdata(client));
217
218 return 0;
219 }
220
221 static const struct i2c_device_id eeprom_id[] = {
222 { "eeprom", 0 },
223 { }
224 };
225
226 static struct i2c_driver eeprom_driver = {
227 .driver = {
228 .name = "eeprom",
229 },
230 .probe = eeprom_probe,
231 .remove = eeprom_remove,
232 .id_table = eeprom_id,
233
234 .class = I2C_CLASS_DDC | I2C_CLASS_SPD,
235 .detect = eeprom_detect,
236 .address_data = &addr_data,
237 };
238
eeprom_init(void)239 static int __init eeprom_init(void)
240 {
241 return i2c_add_driver(&eeprom_driver);
242 }
243
eeprom_exit(void)244 static void __exit eeprom_exit(void)
245 {
246 i2c_del_driver(&eeprom_driver);
247 }
248
249
250 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and "
251 "Philip Edelbrock <phil@netroedge.com> and "
252 "Greg Kroah-Hartman <greg@kroah.com>");
253 MODULE_DESCRIPTION("I2C EEPROM driver");
254 MODULE_LICENSE("GPL");
255
256 module_init(eeprom_init);
257 module_exit(eeprom_exit);
258