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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
19#include <linux/kernel.h>
20#include <linux/init.h>
21#include <linux/module.h>
22#include <linux/slab.h>
23#include <linux/jiffies.h>
24#include <linux/i2c.h>
25#include <linux/mutex.h>
26
27/* Addresses to scan */
28static const unsigned short normal_i2c[] = { 0x50, 0x51, 0x52, 0x53, 0x54,
29 0x55, 0x56, 0x57, I2C_CLIENT_END };
30
31
32/* Size of EEPROM in bytes */
33#define EEPROM_SIZE 256
34
35/* possible types of eeprom devices */
36enum eeprom_nature {
37 UNKNOWN,
38 VAIO,
39};
40
41/* Each client has this additional data */
42struct eeprom_data {
43 struct mutex update_lock;
44 u8 valid; /* bitfield, bit!=0 if slice is valid */
45 unsigned long last_updated[8]; /* In jiffies, 8 slices */
46 u8 data[EEPROM_SIZE]; /* Register values */
47 enum eeprom_nature nature;
48};
49
50
51static void eeprom_update_client(struct i2c_client *client, u8 slice)
52{
53 struct eeprom_data *data = i2c_get_clientdata(client);
54 int i;
55
56 mutex_lock(&data->update_lock);
57
58 if (!(data->valid & (1 << slice)) ||
59 time_after(jiffies, data->last_updated[slice] + 300 * HZ)) {
60 dev_dbg(&client->dev, "Starting eeprom update, slice %u\n", slice);
61
62 if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
63 for (i = slice << 5; i < (slice + 1) << 5; i += 32)
64 if (i2c_smbus_read_i2c_block_data(client, i,
65 32, data->data + i)
66 != 32)
67 goto exit;
68 } else {
69 for (i = slice << 5; i < (slice + 1) << 5; i += 2) {
70 int word = i2c_smbus_read_word_data(client, i);
71 if (word < 0)
72 goto exit;
73 data->data[i] = word & 0xff;
74 data->data[i + 1] = word >> 8;
75 }
76 }
77 data->last_updated[slice] = jiffies;
78 data->valid |= (1 << slice);
79 }
80exit:
81 mutex_unlock(&data->update_lock);
82}
83
84static ssize_t eeprom_read(struct file *filp, struct kobject *kobj,
85 struct bin_attribute *bin_attr,
86 char *buf, loff_t off, size_t count)
87{
88 struct i2c_client *client = to_i2c_client(container_of(kobj, struct device, kobj));
89 struct eeprom_data *data = i2c_get_clientdata(client);
90 u8 slice;
91
92 if (off > EEPROM_SIZE)
93 return 0;
94 if (off + count > EEPROM_SIZE)
95 count = EEPROM_SIZE - off;
96
97 /* Only refresh slices which contain requested bytes */
98 for (slice = off >> 5; slice <= (off + count - 1) >> 5; slice++)
99 eeprom_update_client(client, slice);
100
101 /* Hide Vaio private settings to regular users:
102 - BIOS passwords: bytes 0x00 to 0x0f
103 - UUID: bytes 0x10 to 0x1f
104 - Serial number: 0xc0 to 0xdf */
105 if (data->nature == VAIO && !capable(CAP_SYS_ADMIN)) {
106 int i;
107
108 for (i = 0; i < count; i++) {
109 if ((off + i <= 0x1f) ||
110 (off + i >= 0xc0 && off + i <= 0xdf))
111 buf[i] = 0;
112 else
113 buf[i] = data->data[off + i];
114 }
115 } else {
116 memcpy(buf, &data->data[off], count);
117 }
118
119 return count;
120}
121
122static struct bin_attribute eeprom_attr = {
123 .attr = {
124 .name = "eeprom",
125 .mode = S_IRUGO,
126 },
127 .size = EEPROM_SIZE,
128 .read = eeprom_read,
129};
130
131/* Return 0 if detection is successful, -ENODEV otherwise */
132static int eeprom_detect(struct i2c_client *client, struct i2c_board_info *info)
133{
134 struct i2c_adapter *adapter = client->adapter;
135
136 /* EDID EEPROMs are often 24C00 EEPROMs, which answer to all
137 addresses 0x50-0x57, but we only care about 0x50. So decline
138 attaching to addresses >= 0x51 on DDC buses */
139 if (!(adapter->class & I2C_CLASS_SPD) && client->addr >= 0x51)
140 return -ENODEV;
141
142 /* There are four ways we can read the EEPROM data:
143 (1) I2C block reads (faster, but unsupported by most adapters)
144 (2) Word reads (128% overhead)
145 (3) Consecutive byte reads (88% overhead, unsafe)
146 (4) Regular byte data reads (265% overhead)
147 The third and fourth methods are not implemented by this driver
148 because all known adapters support one of the first two. */
149 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_WORD_DATA)
150 && !i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK))
151 return -ENODEV;
152
153 strlcpy(info->type, "eeprom", I2C_NAME_SIZE);
154
155 return 0;
156}
157
158static int eeprom_probe(struct i2c_client *client,
159 const struct i2c_device_id *id)
160{
161 struct i2c_adapter *adapter = client->adapter;
162 struct eeprom_data *data;
163 int err;
164
165 if (!(data = kzalloc(sizeof(struct eeprom_data), GFP_KERNEL))) {
166 err = -ENOMEM;
167 goto exit;
168 }
169
170 memset(data->data, 0xff, EEPROM_SIZE);
171 i2c_set_clientdata(client, data);
172 mutex_init(&data->update_lock);
173 data->nature = UNKNOWN;
174
175 /* Detect the Vaio nature of EEPROMs.
176 We use the "PCG-" or "VGN-" prefix as the signature. */
177 if (client->addr == 0x57
178 && i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_BYTE_DATA)) {
179 char name[4];
180
181 name[0] = i2c_smbus_read_byte_data(client, 0x80);
182 name[1] = i2c_smbus_read_byte_data(client, 0x81);
183 name[2] = i2c_smbus_read_byte_data(client, 0x82);
184 name[3] = i2c_smbus_read_byte_data(client, 0x83);
185
186 if (!memcmp(name, "PCG-", 4) || !memcmp(name, "VGN-", 4)) {
187 dev_info(&client->dev, "Vaio EEPROM detected, "
188 "enabling privacy protection\n");
189 data->nature = VAIO;
190 }
191 }
192
193 /* create the sysfs eeprom file */
194 err = sysfs_create_bin_file(&client->dev.kobj, &eeprom_attr);
195 if (err)
196 goto exit_kfree;
197
198 return 0;
199
200exit_kfree:
201 kfree(data);
202exit:
203 return err;
204}
205
206static int eeprom_remove(struct i2c_client *client)
207{
208 sysfs_remove_bin_file(&client->dev.kobj, &eeprom_attr);
209 kfree(i2c_get_clientdata(client));
210
211 return 0;
212}
213
214static const struct i2c_device_id eeprom_id[] = {
215 { "eeprom", 0 },
216 { }
217};
218
219static struct i2c_driver eeprom_driver = {
220 .driver = {
221 .name = "eeprom",
222 },
223 .probe = eeprom_probe,
224 .remove = eeprom_remove,
225 .id_table = eeprom_id,
226
227 .class = I2C_CLASS_DDC | I2C_CLASS_SPD,
228 .detect = eeprom_detect,
229 .address_list = normal_i2c,
230};
231
232module_i2c_driver(eeprom_driver);
233
234MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and "
235 "Philip Edelbrock <phil@netroedge.com> and "
236 "Greg Kroah-Hartman <greg@kroah.com>");
237MODULE_DESCRIPTION("I2C EEPROM driver");
238MODULE_LICENSE("GPL");